draft-ietf-gnap-core-protocol-07.txt   draft-ietf-gnap-core-protocol-08.txt 
GNAP J. Richer, Ed. GNAP J. Richer, Ed.
Internet-Draft Bespoke Engineering Internet-Draft Bespoke Engineering
Intended status: Standards Track A. Parecki Intended status: Standards Track A. Parecki
Expires: 28 March 2022 Okta Expires: 28 April 2022 Okta
F. Imbault F. Imbault
acert.io acert.io
24 September 2021 25 October 2021
Grant Negotiation and Authorization Protocol Grant Negotiation and Authorization Protocol
draft-ietf-gnap-core-protocol-07 draft-ietf-gnap-core-protocol-08
Abstract Abstract
GNAP defines a mechanism for delegating authorization to a piece of GNAP defines a mechanism for delegating authorization to a piece of
software, and conveying that delegation to the software. This software, and conveying that delegation to the software. This
delegation can include access to a set of APIs as well as information delegation can include access to a set of APIs as well as information
passed directly to the software. passed directly to the software.
Status of This Memo Status of This Memo
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as described in Section 4.e of the Trust Legal Provisions and are as described in Section 4.e of the Trust Legal Provisions and are
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 5 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 5
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 6 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 6
1.2. Roles . . . . . . . . . . . . . . . . . . . . . . . . . . 6 1.2. Roles . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.3. Elements . . . . . . . . . . . . . . . . . . . . . . . . 9 1.3. Elements . . . . . . . . . . . . . . . . . . . . . . . . 9
1.4. Trust relationships . . . . . . . . . . . . . . . . . . . 10 1.4. Trust relationships . . . . . . . . . . . . . . . . . . . 10
1.5. Sequences . . . . . . . . . . . . . . . . . . . . . . . . 11 1.5. Sequences . . . . . . . . . . . . . . . . . . . . . . . . 12
1.5.1. Redirect-based Interaction . . . . . . . . . . . . . 15 1.5.1. Redirect-based Interaction . . . . . . . . . . . . . 15
1.5.2. User-code Interaction . . . . . . . . . . . . . . . . 18 1.5.2. User-code Interaction . . . . . . . . . . . . . . . . 18
1.5.3. Asynchronous Authorization . . . . . . . . . . . . . 20 1.5.3. Asynchronous Authorization . . . . . . . . . . . . . 20
1.5.4. Software-only Authorization . . . . . . . . . . . . . 22 1.5.4. Software-only Authorization . . . . . . . . . . . . . 22
1.5.5. Refreshing an Expired Access Token . . . . . . . . . 23 1.5.5. Refreshing an Expired Access Token . . . . . . . . . 23
1.5.6. Requesting User Information . . . . . . . . . . . . . 25 1.5.6. Requesting User Information . . . . . . . . . . . . . 25
2. Requesting Access . . . . . . . . . . . . . . . . . . . . . . 26 2. Requesting Access . . . . . . . . . . . . . . . . . . . . . . 26
2.1. Requesting Access to Resources . . . . . . . . . . . . . 28 2.1. Requesting Access to Resources . . . . . . . . . . . . . 28
2.1.1. Requesting a Single Access Token . . . . . . . . . . 28 2.1.1. Requesting a Single Access Token . . . . . . . . . . 28
2.1.2. Requesting Multiple Access Tokens . . . . . . . . . . 31 2.1.2. Requesting Multiple Access Tokens . . . . . . . . . . 31
2.2. Requesting Subject Information . . . . . . . . . . . . . 33 2.2. Requesting Subject Information . . . . . . . . . . . . . 33
2.3. Identifying the Client Instance . . . . . . . . . . . . . 34 2.3. Identifying the Client Instance . . . . . . . . . . . . . 34
2.3.1. Identifying the Client Instance by Reference . . . . 35 2.3.1. Identifying the Client Instance by Reference . . . . 35
2.3.2. Providing Displayable Client Instance Information . . 36 2.3.2. Providing Displayable Client Instance Information . . 36
2.3.3. Authenticating the Client Instance . . . . . . . . . 36 2.3.3. Authenticating the Client Instance . . . . . . . . . 36
2.4. Identifying the User . . . . . . . . . . . . . . . . . . 37 2.4. Identifying the User . . . . . . . . . . . . . . . . . . 37
2.4.1. Identifying the User by Reference . . . . . . . . . . 38 2.4.1. Identifying the User by Reference . . . . . . . . . . 38
2.5. Interacting with the User . . . . . . . . . . . . . . . . 38 2.5. Interacting with the User . . . . . . . . . . . . . . . . 39
2.5.1. Start Mode Definitions . . . . . . . . . . . . . . . 40 2.5.1. Start Mode Definitions . . . . . . . . . . . . . . . 40
2.5.2. Finish Interaction Modes . . . . . . . . . . . . . . 41 2.5.2. Finish Interaction Modes . . . . . . . . . . . . . . 42
2.5.3. Hints . . . . . . . . . . . . . . . . . . . . . . . . 44 2.5.3. Hints . . . . . . . . . . . . . . . . . . . . . . . . 44
2.5.4. Extending Interaction Modes . . . . . . . . . . . . . 44 2.5.4. Extending Interaction Modes . . . . . . . . . . . . . 45
2.6. Extending The Grant Request . . . . . . . . . . . . . . . 44 2.6. Extending The Grant Request . . . . . . . . . . . . . . . 45
3. Grant Response . . . . . . . . . . . . . . . . . . . . . . . 45 3. Grant Response . . . . . . . . . . . . . . . . . . . . . . . 45
3.1. Request Continuation . . . . . . . . . . . . . . . . . . 46 3.1. Request Continuation . . . . . . . . . . . . . . . . . . 47
3.2. Access Tokens . . . . . . . . . . . . . . . . . . . . . . 47 3.2. Access Tokens . . . . . . . . . . . . . . . . . . . . . . 48
3.2.1. Single Access Token . . . . . . . . . . . . . . . . . 48 3.2.1. Single Access Token . . . . . . . . . . . . . . . . . 48
3.2.2. Multiple Access Tokens . . . . . . . . . . . . . . . 51 3.2.2. Multiple Access Tokens . . . . . . . . . . . . . . . 52
3.3. Interaction Modes . . . . . . . . . . . . . . . . . . . . 52 3.3. Interaction Modes . . . . . . . . . . . . . . . . . . . . 53
3.3.1. Redirection to an arbitrary URL . . . . . . . . . . . 53 3.3.1. Redirection to an arbitrary URL . . . . . . . . . . . 54
3.3.2. Launch of an application URL . . . . . . . . . . . . 54 3.3.2. Launch of an application URL . . . . . . . . . . . . 55
3.3.3. Display of a Short User Code . . . . . . . . . . . . 54 3.3.3. Display of a Short User Code . . . . . . . . . . . . 55
3.3.4. Interaction Finish . . . . . . . . . . . . . . . . . 55 3.3.4. Interaction Finish . . . . . . . . . . . . . . . . . 56
3.3.5. Extending Interaction Mode Responses . . . . . . . . 56 3.3.5. Extending Interaction Mode Responses . . . . . . . . 57
3.4. Returning Subject Information . . . . . . . . . . . . . . 56 3.4. Returning Subject Information . . . . . . . . . . . . . . 57
3.5. Returning Dynamically-bound Reference Handles . . . . . . 57 3.5. Returning a Dynamically-bound Client Instance
3.6. Error Response . . . . . . . . . . . . . . . . . . . . . 58 Identifier . . . . . . . . . . . . . . . . . . . . . . . 58
3.7. Extending the Response . . . . . . . . . . . . . . . . . 59 3.6. Error Response . . . . . . . . . . . . . . . . . . . . . 59
4. Determining Authorization and Consent . . . . . . . . . . . . 59 3.7. Extending the Response . . . . . . . . . . . . . . . . . 60
4.1. Interaction Start Methods . . . . . . . . . . . . . . . . 62 4. Determining Authorization and Consent . . . . . . . . . . . . 60
4.1.1. Interaction at a Redirected URI . . . . . . . . . . . 62 4.1. Interaction Start Methods . . . . . . . . . . . . . . . . 63
4.1.2. Interaction at the User Code URI . . . . . . . . . . 63 4.1.1. Interaction at a Redirected URI . . . . . . . . . . . 63
4.1.3. Interaction through an Application URI . . . . . . . 64 4.1.2. Interaction at the User Code URI . . . . . . . . . . 64
4.2. Post-Interaction Completion . . . . . . . . . . . . . . . 64 4.1.3. Interaction through an Application URI . . . . . . . 65
4.2. Post-Interaction Completion . . . . . . . . . . . . . . . 65
4.2.1. Completing Interaction with a Browser Redirect to the 4.2.1. Completing Interaction with a Browser Redirect to the
Callback URI . . . . . . . . . . . . . . . . . . . . 65 Callback URI . . . . . . . . . . . . . . . . . . . . 66
4.2.2. Completing Interaction with a Direct HTTP Request 4.2.2. Completing Interaction with a Direct HTTP Request
Callback . . . . . . . . . . . . . . . . . . . . . . 66 Callback . . . . . . . . . . . . . . . . . . . . . . 67
4.2.3. Calculating the interaction hash . . . . . . . . . . 66 4.2.3. Calculating the interaction hash . . . . . . . . . . 68
5. Continuing a Grant Request . . . . . . . . . . . . . . . . . 68 5. Continuing a Grant Request . . . . . . . . . . . . . . . . . 69
5.1. Continuing After a Completed Interaction . . . . . . . . 70 5.1. Continuing After a Completed Interaction . . . . . . . . 71
5.2. Continuing During Pending Interaction . . . . . . . . . . 71 5.2. Continuing During Pending Interaction . . . . . . . . . . 72
5.3. Modifying an Existing Request . . . . . . . . . . . . . . 73 5.3. Modifying an Existing Request . . . . . . . . . . . . . . 74
5.4. Canceling a Grant Request . . . . . . . . . . . . . . . . 78 5.4. Canceling a Grant Request . . . . . . . . . . . . . . . . 80
6. Token Management . . . . . . . . . . . . . . . . . . . . . . 79 6. Token Management . . . . . . . . . . . . . . . . . . . . . . 80
6.1. Rotating the Access Token . . . . . . . . . . . . . . . . 79 6.1. Rotating the Access Token . . . . . . . . . . . . . . . . 80
6.2. Revoking the Access Token . . . . . . . . . . . . . . . . 81 6.2. Revoking the Access Token . . . . . . . . . . . . . . . . 82
7. Securing Requests from the Client Instance . . . . . . . . . 82 7. Securing Requests from the Client Instance . . . . . . . . . 83
7.1. Key Formats . . . . . . . . . . . . . . . . . . . . . . . 83 7.1. Key Formats . . . . . . . . . . . . . . . . . . . . . . . 84
7.1.1. Key References . . . . . . . . . . . . . . . . . . . 84 7.1.1. Key References . . . . . . . . . . . . . . . . . . . 85
7.2. Presenting Access Tokens . . . . . . . . . . . . . . . . 84 7.2. Presenting Access Tokens . . . . . . . . . . . . . . . . 85
7.3. Proving Possession of a Key with a Request . . . . . . . 85 7.3. Proving Possession of a Key with a Request . . . . . . . 86
7.3.1. HTTP Message Signing . . . . . . . . . . . . . . . . 87 7.3.1. HTTP Message Signing . . . . . . . . . . . . . . . . 88
7.3.2. Mutual TLS . . . . . . . . . . . . . . . . . . . . . 91 7.3.2. Mutual TLS . . . . . . . . . . . . . . . . . . . . . 92
7.3.3. Detached JWS . . . . . . . . . . . . . . . . . . . . 93 7.3.3. Detached JWS . . . . . . . . . . . . . . . . . . . . 94
7.3.4. Attached JWS . . . . . . . . . . . . . . . . . . . . 97 7.3.4. Attached JWS . . . . . . . . . . . . . . . . . . . . 98
8. Resource Access Rights . . . . . . . . . . . . . . . . . . . 101 8. Resource Access Rights . . . . . . . . . . . . . . . . . . . 102
8.1. Requesting Resources By Reference . . . . . . . . . . . . 104 8.1. Requesting Resources By Reference . . . . . . . . . . . . 105
9. Discovery . . . . . . . . . . . . . . . . . . . . . . . . . . 106 9. Discovery . . . . . . . . . . . . . . . . . . . . . . . . . . 107
9.1. RS-first Method of AS Discovery . . . . . . . . . . . . . 107 9.1. RS-first Method of AS Discovery . . . . . . . . . . . . . 108
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 109 10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 110
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 109 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 110
12. Security Considerations . . . . . . . . . . . . . . . . . . . 109 12. Security Considerations . . . . . . . . . . . . . . . . . . . 110
12.1. TLS Protection in Transit . . . . . . . . . . . . . . . 109 12.1. TLS Protection in Transit . . . . . . . . . . . . . . . 110
12.2. Protection of Client Instance Key Material . . . . . . . 110 12.2. Signing Requests from the Client Software . . . . . . . 111
12.3. Protection of Authorization Server . . . . . . . . . . . 111 12.3. Protection of Client Instance Key Material . . . . . . . 112
12.4. Symmetric and Asymmetric Client Instance Keys . . . . . 112 12.4. Protection of Authorization Server . . . . . . . . . . . 114
12.5. Generation of Access Tokens . . . . . . . . . . . . . . 113 12.5. Symmetric and Asymmetric Client Instance Keys . . . . . 114
12.6. Bearer Access Tokens . . . . . . . . . . . . . . . . . . 114 12.6. Generation of Access Tokens . . . . . . . . . . . . . . 115
12.7. Key-Bound Token Access Tokens . . . . . . . . . . . . . 114 12.7. Bearer Access Tokens . . . . . . . . . . . . . . . . . . 116
12.8. Exposure of End-user Credentials to Client Instance . . 115 12.8. Key-Bound Token Access Tokens . . . . . . . . . . . . . 116
12.9. Mixing Up Authorization Servers . . . . . . . . . . . . 116 12.9. Exposure of End-user Credentials to Client Instance . . 117
12.10. Processing of Client-Presented User Information . . . . 117 12.10. Mixing Up Authorization Servers . . . . . . . . . . . . 118
12.11. Client Instance Pre-registration . . . . . . . . . . . . 118 12.11. Processing of Client-Presented User Information . . . . 119
12.12. Client Instance Impersonation . . . . . . . . . . . . . 119 12.12. Client Instance Pre-registration . . . . . . . . . . . . 120
12.13. Interception of Information in the Browser . . . . . . . 120 12.13. Client Instance Impersonation . . . . . . . . . . . . . 121
12.14. Callback URL Manipulation . . . . . . . . . . . . . . . 120 12.14. Interception of Information in the Browser . . . . . . . 122
12.15. MTLS Deployment Patterns . . . . . . . . . . . . . . . . 121 12.15. Callback URL Manipulation . . . . . . . . . . . . . . . 122
12.16. Interception of Responses from the AS . . . . . . . . . 121 12.16. MTLS Message Integrity . . . . . . . . . . . . . . . . . 123
12.17. Key Distribution . . . . . . . . . . . . . . . . . . . . 122 12.17. MTLS Deployment Patterns . . . . . . . . . . . . . . . . 124
12.18. Interaction Finish Modes and Polling . . . . . . . . . . 122 12.18. Interception of Responses from the AS . . . . . . . . . 124
12.19. Storage of Information During Interaction and 12.19. Key Distribution . . . . . . . . . . . . . . . . . . . . 125
Continuation . . . . . . . . . . . . . . . . . . . . . 123 12.20. Interaction Finish Modes and Polling . . . . . . . . . . 125
12.20. Denial of Service (DoS) through Grant Continuation . . . 124 12.21. Storage of Information During Interaction and
12.21. Exhaustion of Random Value Space . . . . . . . . . . . . 124 Continuation . . . . . . . . . . . . . . . . . . . . . 126
13. Privacy Considerations . . . . . . . . . . . . . . . . . . . 125 12.22. Denial of Service (DoS) through Grant Continuation . . . 126
13.1. Surveillance . . . . . . . . . . . . . . . . . . . . . . 125 12.23. Exhaustion of Random Value Space . . . . . . . . . . . . 127
13.1.1. Surveillance by the Client . . . . . . . . . . . . . 125 12.24. Front-channel URLs . . . . . . . . . . . . . . . . . . . 128
13.1.2. Surveillance by the Authorization Server . . . . . . 125 12.25. Processing Assertions . . . . . . . . . . . . . . . . . 129
13.2. Stored Data . . . . . . . . . . . . . . . . . . . . . . 126 13. Privacy Considerations . . . . . . . . . . . . . . . . . . . 129
13.3. Intrusion . . . . . . . . . . . . . . . . . . . . . . . 127 13.1. Surveillance . . . . . . . . . . . . . . . . . . . . . . 129
13.4. Correlation . . . . . . . . . . . . . . . . . . . . . . 127 13.1.1. Surveillance by the Client . . . . . . . . . . . . . 130
13.4.1. Correlation by Clients . . . . . . . . . . . . . . . 127 13.1.2. Surveillance by the Authorization Server . . . . . . 130
13.4.2. Correlation by Resource Servers . . . . . . . . . . 127 13.2. Stored Data . . . . . . . . . . . . . . . . . . . . . . 130
13.4.3. Correlation by Authorization Servers . . . . . . . . 128 13.3. Intrusion . . . . . . . . . . . . . . . . . . . . . . . 131
13.5. Disclosure in Shared References . . . . . . . . . . . . 128 13.4. Correlation . . . . . . . . . . . . . . . . . . . . . . 131
14. References . . . . . . . . . . . . . . . . . . . . . . . . . 128 13.4.1. Correlation by Clients . . . . . . . . . . . . . . . 132
14.1. Normative References . . . . . . . . . . . . . . . . . . 128 13.4.2. Correlation by Resource Servers . . . . . . . . . . 132
14.2. Informative References . . . . . . . . . . . . . . . . . 131 13.4.3. Correlation by Authorization Servers . . . . . . . . 133
Appendix A. Document History . . . . . . . . . . . . . . . . . . 131 13.5. Disclosure in Shared References . . . . . . . . . . . . 133
Appendix B. Compared to OAuth 2.0 . . . . . . . . . . . . . . . 134 14. References . . . . . . . . . . . . . . . . . . . . . . . . . 133
Appendix C. Component Data Models . . . . . . . . . . . . . . . 136 14.1. Normative References . . . . . . . . . . . . . . . . . . 133
Appendix D. Example Protocol Flows . . . . . . . . . . . . . . . 136 14.2. Informative References . . . . . . . . . . . . . . . . . 135
D.1. Redirect-Based User Interaction . . . . . . . . . . . . . 137 Appendix A. Document History . . . . . . . . . . . . . . . . . . 136
D.2. Secondary Device Interaction . . . . . . . . . . . . . . 140 Appendix B. Compared to OAuth 2.0 . . . . . . . . . . . . . . . 139
D.3. No User Involvement . . . . . . . . . . . . . . . . . . . 143 Appendix C. Component Data Models . . . . . . . . . . . . . . . 141
D.4. Asynchronous Authorization . . . . . . . . . . . . . . . 144 Appendix D. Example Protocol Flows . . . . . . . . . . . . . . . 142
D.5. Applying OAuth 2.0 Scopes and Client IDs . . . . . . . . 148 D.1. Redirect-Based User Interaction . . . . . . . . . . . . . 142
Appendix E. JSON Structures and Polymorphism . . . . . . . . . . 149 D.2. Secondary Device Interaction . . . . . . . . . . . . . . 146
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 150 D.3. No User Involvement . . . . . . . . . . . . . . . . . . . 149
D.4. Asynchronous Authorization . . . . . . . . . . . . . . . 150
D.5. Applying OAuth 2.0 Scopes and Client IDs . . . . . . . . 154
Appendix E. JSON Structures and Polymorphism . . . . . . . . . . 155
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 156
1. Introduction 1. Introduction
This protocol allows a piece of software, the client instance, to This protocol allows a piece of software, the client instance, to
request delegated authorization to resource servers and to request request delegated authorization to resource servers and to request
direct information. This delegation is facilitated by an direct information. This delegation is facilitated by an
authorization server usually on behalf of a resource owner. The end- authorization server usually on behalf of a resource owner. The end-
user operating the software may interact with the authorization user operating the software may interact with the authorization
server to authenticate, provide consent, and authorize the request. server to authenticate, provide consent, and authorize the request.
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multiple parties acting in distinct roles. multiple parties acting in distinct roles.
This specification focuses on the portions of the delegation process This specification focuses on the portions of the delegation process
facing the client instance. In particular, this specification facing the client instance. In particular, this specification
defines interoperable methods for a client instance to request, defines interoperable methods for a client instance to request,
negotiate, and receive access to information facilitated by the negotiate, and receive access to information facilitated by the
authorization server. This specification also discusses discovery authorization server. This specification also discusses discovery
mechanisms for the client instance to configure itself dynamically. mechanisms for the client instance to configure itself dynamically.
The means for an authorization server and resource server to The means for an authorization server and resource server to
interoperate are discussed in the companion document, interoperate are discussed in the companion document,
[I-D.draft-ietf-gnap-resource-servers]. [I-D.ietf-gnap-resource-servers].
The focus of this protocol is to provide interoperability between the The focus of this protocol is to provide interoperability between the
different parties acting in each role, and is not to specify different parties acting in each role, and is not to specify
implementation details of each. Where appropriate, GNAP may make implementation details of each. Where appropriate, GNAP may make
recommendations about internal implementation details, but these recommendations about internal implementation details, but these
recommendations are to ensure the security of the overall deployment recommendations are to ensure the security of the overall deployment
rather than to be prescriptive in the implementation. rather than to be prescriptive in the implementation.
This protocol solves many of the same use cases as OAuth 2.0 This protocol solves many of the same use cases as OAuth 2.0
[RFC6749], OpenID Connect [OIDC], and the family of protocols that [RFC6749], OpenID Connect [OIDC], and the family of protocols that
skipping to change at page 6, line 15 skipping to change at page 6, line 15
1.1. Terminology 1.1. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in "OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
This document contains non-normative examples of partial and complete This document contains non-normative examples of partial and complete
HTTP messages, JSON structures, URLs, query components, keys, and HTTP messages, JSON structures, URLs, query components, keys, and
other elements. Some examples use a single trailing backslash '' to other elements. Some examples use a single trailing backslash \ to
indicate line wrapping for long values, as per [RFC8792]. The "\" indicate line wrapping for long values, as per [RFC8792]. The \
character and leading spaces on wrapped lines are not part of the character and leading spaces on wrapped lines are not part of the
value. value.
1.2. Roles 1.2. Roles
The parties in GNAP perform actions under different roles. Roles are The parties in GNAP perform actions under different roles. Roles are
defined by the actions taken and the expectations leveraged on the defined by the actions taken and the expectations leveraged on the
role by the overall protocol. role by the overall protocol.
+-------------+ +------------+ +-------------+ +------------+
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+ + + indicates interaction between a human and computer + + + indicates interaction between a human and computer
----- indicates interaction between two pieces of software ----- indicates interaction between two pieces of software
~ ~ ~ indicates a potential equivalence or out-of-band ~ ~ ~ indicates a potential equivalence or out-of-band
communication between roles communication between roles
Authorization Server (AS) server that grants delegated privileges to Authorization Server (AS) server that grants delegated privileges to
a particular instance of client software in the form of access a particular instance of client software in the form of access
tokens or other information (such as subject information). tokens or other information (such as subject information).
Client application operated by an end-user that consumes resources Client application that consumes resources from one or several RSs,
from one or several RSs, possibly requiring access privileges from possibly requiring access privileges from one or several ASs. The
one or several ASs. Example: a client can be a mobile client is operated by the end-user or it runs autonomously on
application, a web application, etc. Note: this specification behalf of a resource owner.
differentiates between a specific instance (the client instance,
identified by its unique key) and the software running the Example: a client can be a mobile application, a web application,
instance (the client software). For some kinds of client etc.
software, there could be many instances of that software, each
instance with a different key. Note: this specification differentiates between a specific
instance (the client instance, identified by its unique key) and
the software running the instance (the client software). For some
kinds of client software, there could be many instances of that
software, each instance with a different key.
Resource Server (RS) server that provides operations on protected Resource Server (RS) server that provides operations on protected
resources, where operations require a valid access token issued by resources, where operations require a valid access token issued by
an AS. an AS.
Resource Owner (RO) subject entity that may grant or deny operations Resource Owner (RO) subject entity that may grant or deny operations
on resources it has authority upon. Note: the act of granting or on resources it has authority upon.
denying an operation may be manual (i.e. through an interaction
with a physical person) or automatic (i.e. through predefined
organizational rules).
End-user natural person that operates a client instance. Note: that Note: the act of granting or denying an operation may be manual
natural person may or may not be the same entity as the RO. (i.e. through an interaction with a physical person) or automatic
(i.e. through predefined organizational rules).
End-user natural person that operates a client instance.
Note: that natural person may or may not be the same entity as the
RO.
The design of GNAP does not assume any one deployment architecture, The design of GNAP does not assume any one deployment architecture,
but instead attempts to define roles that can be fulfilled in a but instead attempts to define roles that can be fulfilled in a
number of different ways for different use cases. As long as a given number of different ways for different use cases. As long as a given
role fulfills all of its obligations and behaviors as defined by the role fulfills all of its obligations and behaviors as defined by the
protocol, GNAP does not make additional requirements on its structure protocol, GNAP does not make additional requirements on its structure
or setup. or setup.
Multiple roles can be fulfilled by the same party, and a given party Multiple roles can be fulfilled by the same party, and a given party
can switch roles in different instances of the protocol. For can switch roles in different instances of the protocol. For
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communications mechanisms which are considered out of scope of GNAP. communications mechanisms which are considered out of scope of GNAP.
1.3. Elements 1.3. Elements
In addition to the roles above, the protocol also involves several In addition to the roles above, the protocol also involves several
elements that are acted upon by the roles throughout the process. elements that are acted upon by the roles throughout the process.
Attribute characteristics related to a subject. Attribute characteristics related to a subject.
Access Token a data artifact representing a set of rights and/or Access Token a data artifact representing a set of rights and/or
attributes. Note: an access token can be first issued to an attributes.
client instance (requiring authorization by the RO) and
subsequently rotated. Note: an access token can be first issued to an client instance
(requiring authorization by the RO) and subsequently rotated.
Grant (verb): to permit an instance of client software to receive Grant (verb): to permit an instance of client software to receive
some attributes at a specific time and valid for a specific some attributes at a specific time and valid for a specific
duration and/or to exercise some set of delegated rights to access duration and/or to exercise some set of delegated rights to access
a protected resource (noun): the act of granting. a protected resource (noun): the act of granting.
Privilege right or attribute associated with a subject. Note: the Privilege right or attribute associated with a subject.
RO defines and maintains the rights and attributes associated to
the protected resource, and might temporarily delegate some set of Note: the RO defines and maintains the rights and attributes
those privileges to an end-user. This process is refered to as associated to the protected resource, and might temporarily
privilege delegation. delegate some set of those privileges to an end-user. This
process is refered to as privilege delegation.
Protected Resource protected API (Application Programming Interface) Protected Resource protected API (Application Programming Interface)
served by an RS and that can be accessed by a client, if and only served by an RS and that can be accessed by a client, if and only
if a valid access token is provided. Note: to avoid complex if a valid access token is provided.
sentences, the specification document may simply refer to resource
instead of protected resource. Note: to avoid complex sentences, the specification document may
simply refer to resource instead of protected resource.
Right ability given to a subject to perform a given operation on a Right ability given to a subject to perform a given operation on a
resource under the control of an RS. resource under the control of an RS.
Subject person, organization or device. Subject person, organization or device. It decides whether and
under which conditions its attributes can be disclosed to other
parties.
Subject Information statement asserted by an AS about a subject. Subject Information statement asserted by an AS about a subject.
1.4. Trust relationships 1.4. Trust relationships
GNAP defines its trust objective as: "the RO trusts the AS to ensure GNAP defines its trust objective as: "the RO trusts the AS to ensure
access validation and delegation of protected resources to end-users, access validation and delegation of protected resources to end-users,
through third party clients." through third party clients."
This trust objective can be decomposed into trust relationships This trust objective can be decomposed into trust relationships
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* end-user/client: the client acts as a user agent. Depending on * end-user/client: the client acts as a user agent. Depending on
the technology used (browser, SPA, mobile application, IoT device, the technology used (browser, SPA, mobile application, IoT device,
etc.), some interactions may or may not be possible (as described etc.), some interactions may or may not be possible (as described
in Section 2.5.1). Client developers promise to implement in Section 2.5.1). Client developers promise to implement
requirements and generally some recommendations or best practices, requirements and generally some recommendations or best practices,
so that the end-users may confidently use their software. so that the end-users may confidently use their software.
However, end-users might also be facing some attacker's client However, end-users might also be facing some attacker's client
software, without even realizing it. software, without even realizing it.
* end-user / AS: when the client supports it (see Section 3.3), the
end-user gets to interact with front-channel URLs provided by the
AS. See Section 12.24 for some considerations in trusting these
interactions.
* client/AS: An honest AS may be facing an attacker's client (as * client/AS: An honest AS may be facing an attacker's client (as
discussed just above), or the reverse, and GNAP aims at making discussed just above), or the reverse, and GNAP aims at making
common attacks impractical. The core specification makes access common attacks impractical. The core specification makes access
tokens opaque to the client and defines the request/response tokens opaque to the client and defines the request/response
scheme in detail, therefore avoiding extra trust hypotheses from scheme in detail, therefore avoiding extra trust hypotheses from
this critical piece of software. Yet the AS may further define this critical piece of software. Yet the AS may further define
cryptographic attestations or optional rules to simplify the cryptographic attestations or optional rules to simplify the
access of clients it already trusts, due to past behavior or access of clients it already trusts, due to past behavior or
organizational policies (see Section 2.3). organizational policies (see Section 2.3).
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* AS/RO: the AS is expected to follow the decisions made by the RO, * AS/RO: the AS is expected to follow the decisions made by the RO,
either through interactive consent requests, repeated interactions either through interactive consent requests, repeated interactions
or automated rules (as described in Section 1.5). Privacy or automated rules (as described in Section 1.5). Privacy
considerations aim to reduce the risk of an honest but too curious considerations aim to reduce the risk of an honest but too curious
AS, or the consequences of an unexpected user data exposure. AS, or the consequences of an unexpected user data exposure.
* AS/RS: the AS promises to issue valid access tokens to legitimate * AS/RS: the AS promises to issue valid access tokens to legitimate
client requests (i.e. after carrying out appropriate due client requests (i.e. after carrying out appropriate due
diligence, as defined in the GNAP protocol). Some optional diligence, as defined in the GNAP protocol). Some optional
configurations are covered by configurations are covered by [I-D.ietf-gnap-resource-servers].
[I-D.draft-ietf-gnap-resource-servers].
A global assumption made by GNAP is that authorization requests are A global assumption made by GNAP is that authorization requests are
security and privacy sensitive, and appropriate measures are security and privacy sensitive, and appropriate measures are
respectively detailed in Section 12 and Section 13. respectively detailed in Section 12 and Section 13.
A formal trust model is out of scope of this specification, but might A formal trust model is out of scope of this specification, but might
be carried out thanks to [promise-theory]. be carried out thanks to [promise-theory].
1.5. Sequences 1.5. Sequences
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Legend Legend
+ + + indicates a possible interaction with a human + + + indicates a possible interaction with a human
----- indicates an interaction between protocol roles ----- indicates an interaction between protocol roles
~ ~ ~ indicates a potential equivalence or out-of-band ~ ~ ~ indicates a potential equivalence or out-of-band
communication between roles communication between roles
* (A) The end-user interacts with the client instance to indicate a * (A) The end-user interacts with the client instance to indicate a
need for resources on behalf of the RO. This could identify the need for resources on behalf of the RO. This could identify the
RS the client instance needs to call, the resources needed, or the RS the client instance needs to call, the resources needed, or the
RO that is needed to approve the request. Note that the RO and RO that is needed to approve the request. Note that the RO and
end-user are often the same entity in practice, but some more end-user are often the same entity in practice, but GNAP makes no
dynamic processes are discussed in general assumption that they are.
[I-D.draft-ietf-gnap-resource-servers].
* (1) The client instance determines what access is needed and which * (1) The client instance determines what access is needed and which
AS to approach for access. Note that for most situations, the AS to approach for access. Note that for most situations, the
client instance is pre-configured with which AS to talk to and client instance is pre-configured with which AS to talk to and
which kinds of access it needs. which kinds of access it needs, but some more dynamic processes
are discussed in Section 9.1.
* (2) The client instance requests access at the AS (Section 2). * (2) The client instance requests access at the AS (Section 2).
* (3) The AS processes the request and determines what is needed to * (3) The AS processes the request and determines what is needed to
fulfill the request. The AS sends its response to the client fulfill the request. (See Section 4.) The AS sends its response
instance (Section 3). to the client instance (Section 3).
* (B) If interaction is required, the AS interacts with the RO * (B) If interaction is required, the AS interacts with the RO
(Section 4) to gather authorization. The interactive component of (Section 4) to gather authorization. The interactive component of
the AS can function using a variety of possible mechanisms the AS can function using a variety of possible mechanisms
including web page redirects, applications, challenge/response including web page redirects, applications, challenge/response
protocols, or other methods. The RO approves the request for the protocols, or other methods. The RO approves the request for the
client instance being operated by the end-user. Note that the RO client instance being operated by the end-user. Note that the RO
and end-user are often the same entity in practice. and end-user are often the same entity in practice, and many of
GNAP's interaction methods allow the client instance to facilitate
the end user interacting with the AS in order to fulfill the role
of the RO.
* (4) The client instance continues the grant at the AS (Section 5). * (4) The client instance continues the grant at the AS (Section 5).
* (5) If the AS determines that access can be granted, it returns a * (5) If the AS determines that access can be granted, it returns a
response to the client instance (Section 3) including an access response to the client instance (Section 3) including an access
token (Section 3.2) for calling the RS and any directly returned token (Section 3.2) for calling the RS and any directly returned
information (Section 3.4) about the RO. information (Section 3.4) about the RO.
* (6) The client instance uses the access token (Section 7.2) to * (6) The client instance uses the access token (Section 7.2) to
call the RS. call the RS.
* (7) The RS determines if the token is sufficient for the request * (7) The RS determines if the token is sufficient for the request
by examining the token. The means of the RS determining this by examining the token. The means of the RS determining this
access are out of scope of this specification, but some options access are out of scope of this specification, but some options
are discussed in [I-D.draft-ietf-gnap-resource-servers]. are discussed in [I-D.ietf-gnap-resource-servers].
* (8) The client instance calls the RS (Section 7.2) using the * (8) The client instance calls the RS (Section 7.2) using the
access token until the RS or client instance determine that the access token until the RS or client instance determine that the
token is no longer valid. token is no longer valid.
* (9) When the token no longer works, the client instance fetches an * (9) When the token no longer works, the client instance fetches an
updated access token (Section 6.1) based on the rights granted in updated access token (Section 6.1) based on the rights granted in
(5). (5).
* (10) The AS issues a new access token (Section 3.2) to the client * (10) The AS issues a new access token (Section 3.2) to the client
instance. instance.
* (11) The client instance uses the new access token (Section 7.2) * (11) The client instance uses the new access token (Section 7.2)
to call the RS. to call the RS.
* (12) The RS determines if the new token is sufficient for the * (12) The RS determines if the new token is sufficient for the
request. The means of the RS determining this access are out of request. The means of the RS determining this access are out of
scope of this specification, but some options are discussed in scope of this specification, but some options are discussed in
[I-D.draft-ietf-gnap-resource-servers]. [I-D.ietf-gnap-resource-servers].
* (13) The client instance disposes of the token (Section 6.2) once * (13) The client instance disposes of the token (Section 6.2) once
the client instance has completed its access of the RS and no the client instance has completed its access of the RS and no
longer needs the token. longer needs the token.
The following sections and Appendix D contain specific guidance on The following sections and Appendix D contain specific guidance on
how to use GNAP in different situations and deployments. For how to use GNAP in different situations and deployments. For
example, it is possible for the client instance to never request an example, it is possible for the client instance to never request an
access token and never call an RS, just as it is possible for there access token and never call an RS, just as it is possible for there
not to be a user involved in the delegation process. not to be a user involved in the delegation process.
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not request an access token. Instead, the client instance only not request an access token. Instead, the client instance only
requests and is returned direct subject information (Section 3.4). requests and is returned direct subject information (Section 3.4).
Many different interaction modes can be used in this scenario, so Many different interaction modes can be used in this scenario, so
these are shown only in the abstract as functions of the AS here. these are shown only in the abstract as functions of the AS here.
+--------+ +--------+ +------+ +--------+ +--------+ +------+
| Client | | AS | | User | | Client | | AS | | User |
|Instance| | | | | |Instance| | | | |
| |--(1)--- Request Access --------->| | | | | |--(1)--- Request Access --------->| | | |
| | | | | | | | | | | |
| |<-(2)--- Request Access ----------| | | | | |<-(2)-- Interaction Needed -------| | | |
| | | | | | | | | | | |
| |+ (3) + Facilitate Interaction + + + + + + + + + + > | | | |+ (3) + Facilitate Interaction + + + + + + + + + + > | |
| | | | | | | | | | | |
| | | |<+ (4) +>| | | | | |<+ (4) +>| |
| | | | AuthN | | | | | | AuthN | |
| | | | | | | | | | | |
| | | |<+ (5) +>| | | | | |<+ (5) +>| |
| | | | AuthZ | | | | | | AuthZ | |
| | | | | | | | | | | |
| |< (6) + Signal Continuation + + + + + + + + + + + + +| | | |< (6) + Signal Continuation + + + + + + + + + + + + +| |
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"nonce": "LKLTI25DK82FX4T4QFZC" "nonce": "LKLTI25DK82FX4T4QFZC"
} }
}, },
"subject": { "subject": {
"formats": ["iss_sub", "opaque"], "formats": ["iss_sub", "opaque"],
"assertions": ["id_token"] "assertions": ["id_token"]
} }
} }
The request and response MUST be sent as a JSON object in the body of The request and response MUST be sent as a JSON object in the body of
the HTTP POST request with Content-Type "application/json", unless the HTTP POST request with Content-Type application/json, unless
otherwise specified by the signature mechanism. otherwise specified by the signature mechanism.
The authorization server MUST include the HTTP "Cache-Control" The authorization server MUST include the HTTP "Cache-Control"
response header field [RFC7234] with a value set to "no-store". response header field [RFC7234] with a value set to "no-store".
2.1. Requesting Access to Resources 2.1. Requesting Access to Resources
If the client instance is requesting one or more access tokens for If the client instance is requesting one or more access tokens for
the purpose of accessing an API, the client instance MUST include an the purpose of accessing an API, the client instance MUST include an
"access_token" field. This field MUST be an object (for a single access_token field. This field MUST be an object (for a single
access token (Section 2.1.1)) or an array of these objects (for access token (Section 2.1.1)) or an array of these objects (for
multiple access tokens (Section 2.1.2)), as described in the multiple access tokens (Section 2.1.2)), as described in the
following sections. following sections.
2.1.1. Requesting a Single Access Token 2.1.1. Requesting a Single Access Token
To request a single access token, the client instance sends an To request a single access token, the client instance sends an
"acccess_token" object composed of the following fields. acccess_token object composed of the following fields.
access (array of objects/strings) Describes the rights that the access (array of objects/strings) Describes the rights that the
client instance is requesting for one or more access tokens to be client instance is requesting for one or more access tokens to be
used at RS's. This field is REQUIRED. Section 8 used at RS's. This field is REQUIRED. Section 8
label (string) A unique name chosen by the client instance to refer label (string) A unique name chosen by the client instance to refer
to the resulting access token. The value of this field is opaque to the resulting access token. The value of this field is opaque
to the AS. If this field is included in the request, the AS MUST to the AS. If this field is included in the request, the AS MUST
include the same label in the token response (Section 3.2). This include the same label in the token response (Section 3.2). This
field is REQUIRED if used as part of a multiple access token field is REQUIRED if used as part of a multiple access token
request (Section 2.1.2), and is OPTIONAL otherwise. request (Section 2.1.2), and is OPTIONAL otherwise.
flags (array of strings) A set of flags that indicate desired flags (array of strings) A set of flags that indicate desired
attributes or behavior to be attached to the access token by the attributes or behavior to be attached to the access token by the
AS. This field is OPTIONAL. AS. This field is OPTIONAL.
The values of the "flags" field defined by this specification are as The values of the flags field defined by this specification are as
follows: follows:
"bearer" If this flag is included, the access token being requested "bearer" If this flag is included, the access token being requested
is a bearer token. If this flag is omitted, the access token is is a bearer token. If this flag is omitted, the access token is
bound to the key used by the client instance in this request, or bound to the key used by the client instance in this request (or
the key's most recent rotation. Methods for presenting bound and that key's most recent rotation) and the access token MUST be
bearer access tokens are described in Section 7.2. [[ See issue presented using the same key and proofing method. Methods for
#38 (https://github.com/ietf-wg-gnap/gnap-core-protocol/issues/38) presenting bound and bearer access tokens are described in
]] Section 7.2. See Section 12.7 for additional considerations on
the use of bearer tokens.
"split" If this flag is included, the client instance is capable of "split" If this flag is included, the client instance is capable of
receiving a different number of tokens than specified in the token receiving a different number of tokens than specified in the token
request (Section 2.1), including receiving multiple access tokens request (Section 2.1), including receiving multiple access tokens
(Section 3.2.2) in response to any single token request (Section 3.2.2) in response to any single token request
(Section 2.1.1) or a different number of access tokens than (Section 2.1.1) or a different number of access tokens than
requested in a multiple access token request (Section 2.1.2). The requested in a multiple access token request (Section 2.1.2). The
"label" fields of the returned additional tokens are chosen by the label fields of the returned additional tokens are chosen by the
AS. The client instance MUST be able to tell from the token AS. The client instance MUST be able to tell from the token
response where and how it can use each of the access tokens. [[ response where and how it can use each of the access tokens. [[
See issue #37 (https://github.com/ietf-wg-gnap/gnap-core-protocol/ See issue #37 (https://github.com/ietf-wg-gnap/gnap-core-protocol/
issues/37) ]] issues/37) ]]
Flag values MUST NOT be included more than once. Flag values MUST NOT be included more than once.
Additional flags can be defined by extensions using a registry TBD Additional flags can be defined by extensions using a registry TBD
(Section 11). (Section 11).
skipping to change at page 31, line 9 skipping to change at page 31, line 9
If access is approved, the resulting access token is valid for the If access is approved, the resulting access token is valid for the
described resource and is bound to the client instance's key (or its described resource and is bound to the client instance's key (or its
most recent rotation). The token is labeled "token1-23" and could be most recent rotation). The token is labeled "token1-23" and could be
split into multiple access tokens by the AS, if the AS chooses. The split into multiple access tokens by the AS, if the AS chooses. The
token response structure is described in Section 3.2.1. token response structure is described in Section 3.2.1.
2.1.2. Requesting Multiple Access Tokens 2.1.2. Requesting Multiple Access Tokens
To request multiple access tokens to be returned in a single To request multiple access tokens to be returned in a single
response, the client instance sends an array of objects as the value response, the client instance sends an array of objects as the value
of the "access_token" parameter. Each object MUST conform to the of the access_token parameter. Each object MUST conform to the
request format for a single access token request, as specified in request format for a single access token request, as specified in
requesting a single access token (Section 2.1.1). Additionally, each requesting a single access token (Section 2.1.1). Additionally, each
object in the array MUST include the "label" field, and all values of object in the array MUST include the label field, and all values of
these fields MUST be unique within the request. If the client these fields MUST be unique within the request. If the client
instance does not include a "label" value for any entry in the array, instance does not include a label value for any entry in the array,
or the values of the "label" field are not unique within the array, or the values of the label field are not unique within the array, the
the AS MUST return an error. AS MUST return an error.
The following non-normative example shows a request for two separate The following non-normative example shows a request for two separate
access tokens, "token1" and "token2". access tokens, token1 and token2.
"access_token": [ "access_token": [
{ {
"label": "token1", "label": "token1",
"access": [ "access": [
{ {
"type": "photo-api", "type": "photo-api",
"actions": [ "actions": [
"read", "read",
"write", "write",
skipping to change at page 33, line 6 skipping to change at page 33, line 6
"pictures", "pictures",
"walrus whiskers" "walrus whiskers"
] ]
} }
], ],
"flags": [ "bearer" ] "flags": [ "bearer" ]
} }
] ]
All approved access requests are returned in the multiple access All approved access requests are returned in the multiple access
token response (Section 3.2.2) structure using the values of the token response (Section 3.2.2) structure using the values of the
"label" fields in the request. label fields in the request.
2.2. Requesting Subject Information 2.2. Requesting Subject Information
If the client instance is requesting information about the RO from If the client instance is requesting information about the RO from
the AS, it sends a "subject" field as a JSON object. This object MAY the AS, it sends a subject field as a JSON object. This object MAY
contain the following fields (or additional fields defined in a contain the following fields (or additional fields defined in a
registry TBD (Section 11)). registry TBD (Section 11)).
formats (array of strings) An array of subject identifier subject formats (array of strings) An array of subject identifier subject
types requested for the RO, as defined by types requested for the RO, as defined by
[I-D.ietf-secevent-subject-identifiers]. [I-D.ietf-secevent-subject-identifiers].
assertions (array of strings) An array of requested assertion assertions (array of strings) An array of requested assertion
formats. Possible values include "id_token" for an [OIDC] ID formats. Possible values include id_token for an [OIDC] ID Token
Token and "saml2" for a SAML 2 assertion. Additional assertion and saml2 for a SAML 2 assertion. Additional assertion values are
values are defined by a registry TBD (Section 11). [[ See issue defined by a registry TBD (Section 11). [[ See issue #41
#41 (https://github.com/ietf-wg-gnap/gnap-core-protocol/issues/41) (https://github.com/ietf-wg-gnap/gnap-core-protocol/issues/41) ]]
]]
"subject": { "subject": {
"formats": [ "iss_sub", "opaque" ], "formats": [ "iss_sub", "opaque" ],
"assertions": [ "id_token", "saml2" ] "assertions": [ "id_token", "saml2" ]
} }
The AS can determine the RO's identity and permission for releasing The AS can determine the RO's identity and permission for releasing
this information through interaction with the RO (Section 4), AS this information through interaction with the RO (Section 4), AS
policies, or assertions presented by the client instance policies, or assertions presented by the client instance
(Section 2.4). If this is determined positively, the AS MAY return (Section 2.4). If this is determined positively, the AS MAY return
skipping to change at page 33, line 46 skipping to change at page 33, line 45
Subject identifier types requested by the client instance serve only Subject identifier types requested by the client instance serve only
to identify the RO in the context of the AS and can't be used as to identify the RO in the context of the AS and can't be used as
communication channels by the client instance, as discussed in communication channels by the client instance, as discussed in
Section 3.4. Section 3.4.
The AS SHOULD NOT re-use subject identifiers for multiple different The AS SHOULD NOT re-use subject identifiers for multiple different
ROs. ROs.
Note: the "formats" and "assertions" request fields are independent Note: the "formats" and "assertions" request fields are independent
of each other, and a returned assertion MAY omit a requested subject of each other, and a returned assertion MAY use a different subject
identifier. identifier.
[[ See issue #43 (https://github.com/ietf-wg-gnap/gnap-core-protocol/ [[ See issue #43 (https://github.com/ietf-wg-gnap/gnap-core-protocol/
issues/43) ]] issues/43) ]]
2.3. Identifying the Client Instance 2.3. Identifying the Client Instance
When sending a non-continuation request to the AS, the client When sending a non-continuation request to the AS, the client
instance MUST identify itself by including the "client" field of the instance MUST identify itself by including the client field of the
request and by signing the request as described in Section 7.3. Note request and by signing the request as described in Section 7.3. Note
that for a continuation request (Section 5), the client instance is that for a continuation request (Section 5), the client instance is
identified by its association with the request being continued and so identified by its association with the request being continued and so
this field is not sent under those circumstances. this field is not sent under those circumstances.
When client instance information is sent by value, the "client" field When client instance information is sent by value, the client field
of the request consists of a JSON object with the following fields. of the request consists of a JSON object with the following fields.
key (object / string) The public key of the client instance to be key (object / string) The public key of the client instance to be
used in this request as described in Section 7.1 or a reference to used in this request as described in Section 7.1 or a reference to
a key as described in Section 7.1.1. This field is REQUIRED. a key as described in Section 7.1.1. This field is REQUIRED.
class_id (string) An identifier string that the AS can use to class_id (string) An identifier string that the AS can use to
identify the client software comprising this client instance. The identify the client software comprising this client instance. The
contents and format of this field are up to the AS. This field is contents and format of this field are up to the AS. This field is
OPTIONAL. OPTIONAL.
skipping to change at page 35, line 6 skipping to change at page 35, line 6
"class_id": "web-server-1234", "class_id": "web-server-1234",
"display": { "display": {
"name": "My Client Display Name", "name": "My Client Display Name",
"uri": "https://example.net/client" "uri": "https://example.net/client"
} }
} }
Additional fields are defined in a registry TBD (Section 11). Additional fields are defined in a registry TBD (Section 11).
The client instance MUST prove possession of any presented key by the The client instance MUST prove possession of any presented key by the
"proof" mechanism associated with the key in the request. Proof proof mechanism associated with the key in the request. Proof types
types are defined in a registry TBD (Section 11) and an initial set are defined in a registry TBD (Section 11) and an initial set of
of methods is described in Section 7.3. methods is described in Section 7.3.
Note that the AS MAY know the client instance's public key ahead of If the same public key is sent by value on different access requests,
time, and the AS MAY apply different policies to the request the AS MUST treat these requests as coming from the same client
depending on what has been registered against that key. If the same instance for purposes of identification, authentication, and policy
public key is sent by value on subsequent access requests, the AS
SHOULD treat these requests as coming from the same client instance
for purposes of identification, authentication, and policy
application. If the AS does not know the client instance's public application. If the AS does not know the client instance's public
key ahead of time, the AS MAY accept or reject the request based on key ahead of time, the AS MAY accept or reject the request based on
AS policy, attestations within the "client" request, and other AS policy, attestations within the client request, and other
mechanisms. mechanisms.
[[ See issue #44 (https://github.com/ietf-wg-gnap/gnap-core-protocol/ [[ See issue #44 (https://github.com/ietf-wg-gnap/gnap-core-protocol/
issues/44) ]] issues/44) ]]
The client instance MUST NOT send a symmetric key by value in the
request, as doing so would expose the key directly instead of simply
proving possession of it. See considerations on symmetric keys in
Section 12.5.
The client instance's key MAY be pre-registered with the AS ahead of
time and associated with a set of policies and allowable actions
pertaining to that client. If this pre-registration includes other
fields that can occur in the client request object described in this
section, such as class_id or display, the pre-registered values MUST
take precedence over any values given at runtime. Additional fields
sent during a request but not present in a pre-registered client
instance record at the AS SHOULD NOT be added to the client's pre-
registered record. See additional considerations regarding client
instance impersonation in Section 12.13.
2.3.1. Identifying the Client Instance by Reference 2.3.1. Identifying the Client Instance by Reference
If the client instance has an instance identifier that the AS can use If the client instance has an instance identifier that the AS can use
to determine appropriate key information, the client instance can to determine appropriate key information, the client instance can
send this instance identifier as a direct reference value in lieu of send this instance identifier as a direct reference value in lieu of
the "client" object. The instance identifier MAY be assigned to a the client object. The instance identifier MAY be assigned to a
client instance at runtime through the Section 3.5 or MAY be obtained client instance at runtime through the Section 3.5 or MAY be obtained
in another fashion, such as a static registration process at the AS. in another fashion, such as a static registration process at the AS.
"client": "client-541-ab" "client": "client-541-ab"
When the AS receives a request with an instance identifier, the AS When the AS receives a request with an instance identifier, the AS
MUST ensure that the key used to sign the request (Section 7.3) is MUST ensure that the key used to sign the request (Section 7.3) is
associated with the instance identifier. associated with the instance identifier.
If the AS does not recognize the instance identifier, the request If the AS does not recognize the instance identifier, the request
MUST be rejected with an error. MUST be rejected with an error.
If the client instance is identified in this manner, the registered If the client instance is identified in this manner, the registered
key for the client instance MAY be a symmetric key known to the AS. key for the client instance MAY be a symmetric key known to the AS.
The client instance MUST NOT send a symmetric key by value in the See considerations on symmetric keys in Section 12.5.
request, as doing so would expose the key directly instead of proving
possession of it.
2.3.2. Providing Displayable Client Instance Information 2.3.2. Providing Displayable Client Instance Information
If the client instance has additional information to display to the If the client instance has additional information to display to the
RO during any interactions at the AS, it MAY send that information in RO during any interactions at the AS, it MAY send that information in
the "display" field. This field is a JSON object that declares the "display" field. This field is a JSON object that declares
information to present to the RO during any interactive sequences. information to present to the RO during any interactive sequences.
name (string) Display name of the client software name (string) Display name of the client software
skipping to change at page 36, line 32 skipping to change at page 36, line 39
[[ See issue #48 (https://github.com/ietf-wg-gnap/gnap-core-protocol/ [[ See issue #48 (https://github.com/ietf-wg-gnap/gnap-core-protocol/
issues/48) ]] issues/48) ]]
Additional display fields are defined by a registry TBD (Section 11). Additional display fields are defined by a registry TBD (Section 11).
The AS SHOULD use these values during interaction with the RO. The The AS SHOULD use these values during interaction with the RO. The
values are for informational purposes only and MUST NOT be taken as values are for informational purposes only and MUST NOT be taken as
authentic proof of the client instance's identity or source. The AS authentic proof of the client instance's identity or source. The AS
MAY restrict display values to specific client instances, as MAY restrict display values to specific client instances, as
identified by their keys in Section 2.3. identified by their keys in Section 2.3. See additional
considerations for displayed client information in Section 12.13.
2.3.3. Authenticating the Client Instance 2.3.3. Authenticating the Client Instance
If the presented key is known to the AS and is associated with a If the presented key is known to the AS and is associated with a
single instance of the client software, the process of presenting a single instance of the client software, the process of presenting a
key and proving possession of that key is sufficient to authenticate key and proving possession of that key is sufficient to authenticate
the client instance to the AS. The AS MAY associate policies with the client instance to the AS. The AS MAY associate policies with
the client instance identified by this key, such as limiting which the client instance identified by this key, such as limiting which
resources can be requested and which interaction methods can be used. resources can be requested and which interaction methods can be used.
For example, only specific client instances with certain known keys For example, only specific client instances with certain known keys
skipping to change at page 37, line 26 skipping to change at page 37, line 34
If the client instance knows the identity of the end-user through one If the client instance knows the identity of the end-user through one
or more identifiers or assertions, the client instance MAY send that or more identifiers or assertions, the client instance MAY send that
information to the AS in the "user" field. The client instance MAY information to the AS in the "user" field. The client instance MAY
pass this information by value or by reference. pass this information by value or by reference.
sub_ids (array of objects) An array of subject identifiers for the sub_ids (array of objects) An array of subject identifiers for the
end-user, as defined by [I-D.ietf-secevent-subject-identifiers]. end-user, as defined by [I-D.ietf-secevent-subject-identifiers].
assertions (object) An object containing assertions as values keyed assertions (object) An object containing assertions as values keyed
on the assertion type defined by a registry TBD (Section 11). on the assertion type defined by a registry TBD (Section 11).
Possible keys include "id_token" for an [OIDC] ID Token and Possible keys include id_token for an [OIDC] ID Token and saml2
"saml2" for a SAML 2 assertion. Additional assertion values are for a SAML 2 assertion. The assertion values are the string
defined by a registry TBD (Section 11). [[ See issue #41 serialization of the assertion format, encoded as a plain JSON
(https://github.com/ietf-wg-gnap/gnap-core-protocol/issues/41) ]] string. Additional assertion types are defined by a registry TBD
(Section 11). [[ See issue #41 (https://github.com/ietf-wg-gnap/
gnap-core-protocol/issues/41) ]]
"user": { "user": {
"sub_ids": [ { "sub_ids": [ {
"format": "opaque", "format": "opaque",
"id": "J2G8G8O4AZ" "id": "J2G8G8O4AZ"
} ], } ],
"assertions": { "assertions": {
"id_token": "eyj..." "id_token": "eyj..."
} }
} }
skipping to change at page 38, line 13 skipping to change at page 38, line 22
error. error.
[[ See issue #50 (https://github.com/ietf-wg-gnap/gnap-core-protocol/ [[ See issue #50 (https://github.com/ietf-wg-gnap/gnap-core-protocol/
issues/50) ]] issues/50) ]]
If the AS trusts the client instance to present verifiable If the AS trusts the client instance to present verifiable
assertions, the AS MAY decide, based on its policy, to skip assertions, the AS MAY decide, based on its policy, to skip
interaction with the RO, even if the client instance provides one or interaction with the RO, even if the client instance provides one or
more interaction modes in its request. more interaction modes in its request.
See Section 12.25 for considerations that the AS has to make when
accepting and processing assertions from the client instance.
2.4.1. Identifying the User by Reference 2.4.1. Identifying the User by Reference
The AS can identify the current end-user to the client instance with The AS can identify the current end-user to the client instance with
a reference which can be used by the client instance to refer to the a reference which can be used by the client instance to refer to the
end-user across multiple requests. If the client instance has a end-user across multiple requests. If the client instance has a
reference for the end-user at this AS, the client instance MAY pass reference for the end-user at this AS, the client instance MAY pass
that reference as a string. The format of this string is opaque to that reference as a string. The format of this string is opaque to
the client instance. the client instance.
"user": "XUT2MFM1XBIKJKSDU8QM" "user": "XUT2MFM1XBIKJKSDU8QM"
One means of dynamically obtaining such a user reference is from the One means of dynamically obtaining such a user reference is from the
AS returning an "opaque" subject identifier as described in AS returning an opaque subject identifier as described in
Section 3.4. Other means of configuring a client instance with a Section 3.4. Other means of configuring a client instance with a
user identifier are out of scope of this specification. user identifier are out of scope of this specification.
User reference identifiers are not intended to be human-readable user User reference identifiers are not intended to be human-readable user
identifiers or structured assertions. For the client instance to identifiers or structured assertions. For the client instance to
send either of these, use the full user request object (Section 2.4) send either of these, use the full user request object (Section 2.4)
instead. instead.
If the AS does not recognize the user reference, it MUST return an If the AS does not recognize the user reference, it MUST return an
error. error.
skipping to change at page 38, line 52 skipping to change at page 39, line 20
the end-user using the client instance is the same person as the RO, the end-user using the client instance is the same person as the RO,
and the client instance can directly drive interaction with the end and the client instance can directly drive interaction with the end
user by facilitating the process through means such as redirection to user by facilitating the process through means such as redirection to
a URL or launching an application. Other times, the client instance a URL or launching an application. Other times, the client instance
can provide information to start the RO's interaction on a secondary can provide information to start the RO's interaction on a secondary
device, or the client instance will wait for the RO to approve the device, or the client instance will wait for the RO to approve the
request asynchronously. The client instance could also be signaled request asynchronously. The client instance could also be signaled
that interaction has concluded through a callback mechanism. that interaction has concluded through a callback mechanism.
The client instance declares the parameters for interaction methods The client instance declares the parameters for interaction methods
that it can support using the "interact" field. that it can support using the interact field.
The "interact" field is a JSON object with three keys whose values The interact field is a JSON object with three keys whose values
declare how the client can initiate and complete the request, as well declare how the client can initiate and complete the request, as well
as provide hints to the AS about user preferences such as locale. A as provide hints to the AS about user preferences such as locale. A
client instance MUST NOT declare an interaction mode it does not client instance MUST NOT declare an interaction mode it does not
support. The client instance MAY send multiple modes in the same support. The client instance MAY send multiple modes in the same
request. There is no preference order specified in this request. An request. There is no preference order specified in this request. An
AS MAY respond to any, all, or none of the presented interaction AS MAY respond to any, all, or none of the presented interaction
modes (Section 3.3) in a request, depending on its capabilities and modes (Section 3.3) in a request, depending on its capabilities and
what is allowed to fulfill the request. what is allowed to fulfill the request.
start (list of strings/objects) Indicates how the client instance start (list of strings/objects) Indicates how the client instance
can start an interaction. can start an interaction.
finish (object) Indicates how the client instance can receive an finish (object) Indicates how the client instance can receive an
indication that interaction has finished at the AS. indication that interaction has finished at the AS.
hints (object) Provides additional information to inform the hints (object) Provides additional information to inform the
interaction process at the AS. interaction process at the AS.
The "interact" field MUST contain the "start" key, and MAY contain The interact field MUST contain the start key, and MAY contain the
the "finish" and "hints" keys. The value of each key is an array finish and hints keys. The value of each key is an array which
which contains strings or JSON objects as defined below. contains strings or JSON objects as defined below.
In this non-normative example, the client instance is indicating that In this non-normative example, the client instance is indicating that
it can redirect (Section 2.5.1.1) the end-user to an arbitrary URL it can redirect (Section 2.5.1.1) the end-user to an arbitrary URL
and can receive a redirect (Section 2.5.2.1) through a browser and can receive a redirect (Section 2.5.2.1) through a browser
request. request.
"interact": { "interact": {
"start": ["redirect"], "start": ["redirect"],
"finish": { "finish": {
"method": "redirect", "method": "redirect",
skipping to change at page 40, line 17 skipping to change at page 40, line 36
error since the client instance will be unable to complete the error since the client instance will be unable to complete the
request without authorization. request without authorization.
The AS SHOULD apply suitable timeouts to any interaction mechanisms The AS SHOULD apply suitable timeouts to any interaction mechanisms
provided, including user codes and redirection URLs. The client provided, including user codes and redirection URLs. The client
instance SHOULD apply suitable timeouts to any callback URLs. instance SHOULD apply suitable timeouts to any callback URLs.
2.5.1. Start Mode Definitions 2.5.1. Start Mode Definitions
This specification defines the following interaction start modes as This specification defines the following interaction start modes as
an array of string values under the "start" key: an array of string values under the start key:
"redirect" Indicates that the client instance can direct the end- "redirect" Indicates that the client instance can direct the end-
user to an arbitrary URL for interaction. Section 2.5.1.1 user to an arbitrary URL for interaction. Section 2.5.1.1
"app" Indicates that the client instance can launch an application "app" Indicates that the client instance can launch an application
on the end-user's device for interaction. Section 2.5.1.2 on the end-user's device for interaction. Section 2.5.1.2
"user_code" Indicates that the client instance can communicate a "user_code" Indicates that the client instance can communicate a
human-readable short code to the end-user for use with a stable human-readable short code to the end-user for use with a stable
URL. Section 2.5.1.3 URL. Section 2.5.1.3
2.5.1.1. Redirect to an Arbitrary URL 2.5.1.1. Redirect to an Arbitrary URL
If the client instance is capable of directing the end-user to a URL If the client instance is capable of directing the end-user to a URL
defined by the AS at runtime, the client instance indicates this by defined by the AS at runtime, the client instance indicates this by
sending the "redirect" field with the boolean value "true". The including redirect in the array under the start key. The means by
means by which the client instance will activate this URL is out of which the client instance will activate this URL is out of scope of
scope of this specification, but common methods include an HTTP this specification, but common methods include an HTTP redirect,
redirect, launching a browser on the end-user's device, providing a launching a browser on the end-user's device, providing a scannable
scannable image encoding, and printing out a URL to an interactive image encoding, and printing out a URL to an interactive console.
console. While this URL is generally hosted at the AS, the client While this URL is generally hosted at the AS, the client instance can
instance can make no assumptions about its contents, composition, or make no assumptions about its contents, composition, or relationship
relationship to the AS grant URL. to the AS grant URL.
"interact": { "interact": {
"start": ["redirect"] "start": ["redirect"]
} }
If this interaction mode is supported for this client instance and If this interaction mode is supported for this client instance and
request, the AS returns a redirect interaction response request, the AS returns a redirect interaction response
Section 3.3.1. The client instance manages this interaction method Section 3.3.1. The client instance manages this interaction method
as described in Section 4.1.1. as described in Section 4.1.1.
See Section 12.24 for more considerations regarding the use of front-
channel communication techniques such as this.
2.5.1.2. Open an Application-specific URL 2.5.1.2. Open an Application-specific URL
If the client instance can open a URL associated with an application If the client instance can open a URL associated with an application
on the end-user's device, the client instance indicates this by on the end-user's device, the client instance indicates this by
sending the "app" field with boolean value "true". The means by including app in the array under the start key. The means by which
which the client instance determines the application to open with the client instance determines the application to open with this URL
this URL are out of scope of this specification. are out of scope of this specification.
"interact": { "interact": {
"start": ["app"] "start": ["app"]
} }
If this interaction mode is supported for this client instance and If this interaction mode is supported for this client instance and
request, the AS returns an app interaction response with an app URL request, the AS returns an app interaction response with an app URL
payload Section 3.3.2. The client instance manages this interaction payload Section 3.3.2. The client instance manages this interaction
method as described in Section 4.1.3. method as described in Section 4.1.3.
[[ See issue #54 (https://github.com/ietf-wg-gnap/gnap-core-protocol/ [[ See issue #54 (https://github.com/ietf-wg-gnap/gnap-core-protocol/
issues/54) ]] issues/54) ]]
2.5.1.3. Display a Short User Code 2.5.1.3. Display a Short User Code
If the client instance is capable of displaying or otherwise If the client instance is capable of displaying or otherwise
communicating a short, human-entered code to the RO, the client communicating a short, human-entered code to the RO, the client
instance indicates this by sending the "user_code" field with the instance indicates this by including user_code in the array under the
boolean value "true". This code is to be entered at a static URL start key. This code is to be entered at a static URL that does not
that does not change at runtime. While this URL is generally hosted change at runtime. While this URL is generally hosted at the AS, the
at the AS, the client instance can make no assumptions about its client instance can make no assumptions about its contents,
contents, composition, or relationship to the AS grant URL. composition, or relationship to the AS grant URL.
"interact": { "interact": {
"start": ["user_code"] "start": ["user_code"]
} }
If this interaction mode is supported for this client instance and If this interaction mode is supported for this client instance and
request, the AS returns a user code and interaction URL as specified request, the AS returns a user code and interaction URL as specified
in Section 3.3.3. The client instances manages this interaction in Section 3.3.3. The client instances manages this interaction
method as described in Section 4.1.2 method as described in Section 4.1.2
2.5.2. Finish Interaction Modes 2.5.2. Finish Interaction Modes
If the client instance is capable of receiving a message from the AS If the client instance is capable of receiving a message from the AS
indicating that the RO has completed their interaction, the client indicating that the RO has completed their interaction, the client
instance indicates this by sending the following members of an object instance indicates this by sending the following members of an object
under the "finish" key. under the finish key.
method (string) REQUIRED. The callback method that the AS will use method (string) REQUIRED. The callback method that the AS will use
to contact the client instance. This specification defines the to contact the client instance. This specification defines the
following interaction completion methods, with other values following interaction completion methods, with other values
defined by a registry TBD (Section 11): defined by a registry TBD (Section 11):
"redirect" Indicates that the client instance can receive a "redirect" Indicates that the client instance can receive a
redirect from the end-user's device after interaction with the redirect from the end-user's device after interaction with the
RO has concluded. Section 2.5.2.1 RO has concluded. Section 2.5.2.1
skipping to change at page 42, line 37 skipping to change at page 43, line 16
information. The callback URI SHOULD be presented to the RO information. The callback URI SHOULD be presented to the RO
during the interaction phase before redirect. during the interaction phase before redirect.
nonce (string) REQUIRED. Unique value to be used in the calculation nonce (string) REQUIRED. Unique value to be used in the calculation
of the "hash" query parameter sent to the callback URL, must be of the "hash" query parameter sent to the callback URL, must be
sufficiently random to be unguessable by an attacker. MUST be sufficiently random to be unguessable by an attacker. MUST be
generated by the client instance as a unique value for this generated by the client instance as a unique value for this
request. request.
hash_method (string) OPTIONAL. The hash calculation mechanism to be hash_method (string) OPTIONAL. The hash calculation mechanism to be
used for the callback hash in Section 4.2.3. Can be one of "sha3" used for the callback hash in Section 4.2.3. Can be one of sha3
or "sha2". If absent, the default value is "sha3". [[ See issue or sha2. If absent, the default value is sha3. [[ See issue #56
#56 (https://github.com/ietf-wg-gnap/gnap-core-protocol/issues/56) (https://github.com/ietf-wg-gnap/gnap-core-protocol/issues/56) ]]
]]
If this interaction mode is supported for this client instance and If this interaction mode is supported for this client instance and
request, the AS returns a nonce for use in validating the callback request, the AS returns a nonce for use in validating the callback
response (Section 3.3.4). Requests to the callback URI MUST be response (Section 3.3.4). Requests to the callback URI MUST be
processed as described in Section 4.2, and the AS MUST require processed as described in Section 4.2, and the AS MUST require
presentation of an interaction callback reference as described in presentation of an interaction callback reference as described in
Section 5.1. Section 5.1.
[[ See issue #58 (https://github.com/ietf-wg-gnap/gnap-core-protocol/ [[ See issue #58 (https://github.com/ietf-wg-gnap/gnap-core-protocol/
issues/58) ]] issues/58) ]]
[[ See issue #59 (https://github.com/ietf-wg-gnap/gnap-core-protocol/
issues/59) ]]
2.5.2.1. Receive an HTTP Callback Through the Browser 2.5.2.1. Receive an HTTP Callback Through the Browser
A finish "method" value of "redirect" indicates that the client A finish method value of redirect indicates that the client instance
instance will expect a request from the RO's browser using the HTTP will expect a request from the RO's browser using the HTTP method GET
method GET as described in Section 4.2.1. as described in Section 4.2.1.
"interact": { "interact": {
"finish": { "finish": {
"method": "redirect", "method": "redirect",
"uri": "https://client.example.net/return/123455", "uri": "https://client.example.net/return/123455",
"nonce": "LKLTI25DK82FX4T4QFZC" "nonce": "LKLTI25DK82FX4T4QFZC"
} }
} }
Requests to the callback URI MUST be processed by the client instance Requests to the callback URI MUST be processed by the client instance
as described in Section 4.2.1. as described in Section 4.2.1.
Since the incoming request to the callback URL is from the RO's Since the incoming request to the callback URL is from the RO's
browser, this method is usually used when the RO and end-user are the browser, this method is usually used when the RO and end-user are the
same entity. As such, the client instance MUST ensure the end-user same entity. As such, the client instance MUST ensure the end-user
is present on the request to prevent substitution attacks. is present on the request to prevent substitution attacks.
See Section 12.24 for more considerations regarding the use of front-
channel communication techniques such as this.
2.5.2.2. Receive an HTTP Direct Callback 2.5.2.2. Receive an HTTP Direct Callback
A finish "method" value of "push" indicates that the client instance A finish method value of push indicates that the client instance will
will expect a request from the AS directly using the HTTP method POST expect a request from the AS directly using the HTTP method POST as
as described in Section 4.2.2. described in Section 4.2.2.
"interact": { "interact": {
"finish": { "finish": {
"method": "push", "method": "push",
"uri": "https://client.example.net/return/123455", "uri": "https://client.example.net/return/123455",
"nonce": "LKLTI25DK82FX4T4QFZC" "nonce": "LKLTI25DK82FX4T4QFZC"
} }
} }
Requests to the callback URI MUST be processed by the client instance Requests to the callback URI MUST be processed by the client instance
as described in Section 4.2.2. as described in Section 4.2.2.
Since the incoming request to the callback URL is from the AS and not Since the incoming request to the callback URL is from the AS and not
from the RO's browser, the client instance MUST NOT require the end- from the RO's browser, the client instance MUST NOT require the end-
user to be present on the incoming HTTP request. user to be present on the incoming HTTP request.
[[ See issue #60 (https://github.com/ietf-wg-gnap/gnap-core-protocol/
issues/60) ]]
2.5.3. Hints 2.5.3. Hints
The "hints" key is an object describing one or more suggestions from The hints key is an object describing one or more suggestions from
the client instance that the AS can use to help drive user the client instance that the AS can use to help drive user
interaction. interaction.
This specification defines the following properties under the "hints" This specification defines the following properties under the hints
key: key:
ui_locales (array of strings) Indicates the end-user's preferred ui_locales (array of strings) Indicates the end-user's preferred
locales that the AS can use during interaction, particularly locales that the AS can use during interaction, particularly
before the RO has authenticated. Section 2.5.3.1 before the RO has authenticated. Section 2.5.3.1
The following sections detail requests for interaction modes. The following sections detail requests for interaction modes.
Additional interaction modes are defined in a registry TBD Additional interaction modes are defined in a registry TBD
(Section 11). (Section 11).
2.5.3.1. Indicate Desired Interaction Locales 2.5.3.1. Indicate Desired Interaction Locales
If the client instance knows the end-user's locale and language If the client instance knows the end-user's locale and language
preferences, the client instance can send this information to the AS preferences, the client instance can send this information to the AS
using the "ui_locales" field with an array of locale strings as using the ui_locales field with an array of locale strings as defined
defined by [RFC5646]. by [RFC5646].
"interact": { "interact": {
"hints": { "hints": {
"ui_locales": ["en-US", "fr-CA"] "ui_locales": ["en-US", "fr-CA"]
} }
} }
If possible, the AS SHOULD use one of the locales in the array, with If possible, the AS SHOULD use one of the locales in the array, with
preference to the first item in the array supported by the AS. If preference to the first item in the array supported by the AS. If
none of the given locales are supported, the AS MAY use a default none of the given locales are supported, the AS MAY use a default
skipping to change at page 46, line 32 skipping to change at page 47, line 8
} }
} }
In this example, the AS is returning set of subject identifiers In this example, the AS is returning set of subject identifiers
(Section 3.4), simultaneously as an opaque identifier, an email (Section 3.4), simultaneously as an opaque identifier, an email
address, and a decentralized identifier (DID). address, and a decentralized identifier (DID).
{ {
"subject": { "subject": {
"sub_ids": [ { "sub_ids": [ {
"subject_type": "opaque", "format": "opaque",
"id": "J2G8G8O4AZ" "id": "J2G8G8O4AZ"
}, { }, {
"format": "email", "format": "email",
"email": "user@example.com" "email": "user@example.com"
}, { }, {
"format": "did", "format": "did",
"url": "did:example:123456" "url": "did:example:123456"
} ] } ]
} }
} }
3.1. Request Continuation 3.1. Request Continuation
If the AS determines that the request can be continued with If the AS determines that the request can be continued with
additional requests, it responds with the "continue" field. This additional requests, it responds with the continue field. This field
field contains a JSON object with the following properties. contains a JSON object with the following properties.
uri (string) REQUIRED. The URI at which the client instance can uri (string) REQUIRED. The URI at which the client instance can
make continuation requests. This URI MAY vary per request, or MAY make continuation requests. This URI MAY vary per request, or MAY
be stable at the AS if the AS includes an access token. The be stable at the AS. The client instance MUST use this value
client instance MUST use this value exactly as given when making a exactly as given when making a continuation request (Section 5).
continuation request (Section 5).
wait (integer) RECOMMENDED. The amount of time in integer seconds wait (integer) RECOMMENDED. The amount of time in integer seconds
the client instance SHOULD wait after receiving this continuation the client instance SHOULD wait after receiving this continuation
handle and calling the URI. handle and calling the URI.
access_token (object) REQUIRED. A unique access token for access_token (object) REQUIRED. A unique access token for
continuing the request, in the format specified in Section 3.2.1. continuing the request, called the "continuation access token".
This access token MUST be bound to the client instance's key used The value of this property MUST be in the format specified in
in the request and MUST NOT be a "bearer" token. As a Section 3.2.1. This access token MUST be bound to the client
consequence, the "flags" array of this access token MUST NOT instance's key used in the request and MUST NOT be a bearer token.
contain the string "bearer" and the "key" field MUST be omitted. As a consequence, the flags array of this access token MUST NOT
This access token MUST NOT be usable at resources outside of the contain the string bearer and the key field MUST be omitted. The
AS. The client instance MUST present the access token in all client instance MUST present the continuation access token in all
requests to the continuation URI as described in Section 7.2. [[ requests to the continuation URI as described in Section 7.2.
See issue #66 (https://github.com/ietf-wg-gnap/gnap-core-protocol/
issues/66) ]]
{ {
"continue": { "continue": {
"access_token": { "access_token": {
"value": "80UPRY5NM33OMUKMKSKU" "value": "80UPRY5NM33OMUKMKSKU"
}, },
"uri": "https://server.example.com/continue", "uri": "https://server.example.com/continue",
"wait": 60 "wait": 60
} }
} }
skipping to change at page 47, line 48 skipping to change at page 48, line 28
Section 7.3 and MUST present the access token in its continuation Section 7.3 and MUST present the access token in its continuation
request. request.
This field SHOULD be returned when interaction is expected, to allow This field SHOULD be returned when interaction is expected, to allow
the client instance to follow up after interaction has been the client instance to follow up after interaction has been
concluded. concluded.
3.2. Access Tokens 3.2. Access Tokens
If the AS has successfully granted one or more access tokens to the If the AS has successfully granted one or more access tokens to the
client instance, the AS responds with the "access_token" field. This client instance, the AS responds with the access_token field. This
field contains either a single access token as described in field contains either a single access token as described in
Section 3.2.1 or an array of access tokens as described in Section 3.2.1 or an array of access tokens as described in
Section 3.2.2. Section 3.2.2.
The client instance uses any access tokens in this response to call The client instance uses any access tokens in this response to call
the RS as described in Section 7.2. the RS as described in Section 7.2.
3.2.1. Single Access Token 3.2.1. Single Access Token
If the client instance has requested a single access token and the AS If the client instance has requested a single access token and the AS
skipping to change at page 48, line 22 skipping to change at page 49, line 4
"access_token" field. The value of this field is an object with the "access_token" field. The value of this field is an object with the
following properties. following properties.
value (string) REQUIRED. The value of the access token as a string. value (string) REQUIRED. The value of the access token as a string.
The value is opaque to the client instance. The value SHOULD be The value is opaque to the client instance. The value SHOULD be
limited to ASCII characters to facilitate transmission over HTTP limited to ASCII characters to facilitate transmission over HTTP
headers within other protocols without requiring additional headers within other protocols without requiring additional
encoding. encoding.
label (string) REQUIRED for multiple access tokens, OPTIONAL for label (string) REQUIRED for multiple access tokens, OPTIONAL for
single access token. The value of the "label" the client instance single access token. The value of the label the client instance
provided in the associated token request (Section 2.1), if provided in the associated token request (Section 2.1), if
present. If the token has been split by the AS, the value of the present. If the token has been split by the AS, the value of the
"label" field is chosen by the AS and the "split" field is label field is chosen by the AS and the split flag is used.
included and set to "true".
manage (string) OPTIONAL. The management URI for this access token. manage (string) OPTIONAL. The management URI for this access token.
If provided, the client instance MAY manage its access token as If provided, the client instance MAY manage its access token as
described in Section 6. This management URI is a function of the described in Section 6. This management URI is a function of the
AS and is separate from the RS the client instance is requesting AS and is separate from the RS the client instance is requesting
access to. This URI MUST NOT include the access token value and access to. This URI MUST NOT include the access token value and
SHOULD be different for each access token issued in a request. SHOULD be different for each access token issued in a request.
access (array of objects/strings) RECOMMENDED. A description of the access (array of objects/strings) RECOMMENDED. A description of the
rights associated with this access token, as defined in Section 8. rights associated with this access token, as defined in Section 8.
skipping to change at page 49, line 8 skipping to change at page 49, line 37
key (object / string) OPTIONAL. The key that the token is bound to, key (object / string) OPTIONAL. The key that the token is bound to,
if different from the client instance's presented key. The key if different from the client instance's presented key. The key
MUST be an object or string in a format described in Section 7.1. MUST be an object or string in a format described in Section 7.1.
The client instance MUST be able to dereference or process the key The client instance MUST be able to dereference or process the key
information in order to be able to sign the request. information in order to be able to sign the request.
flags (array of strings) OPTIONAL. A set of flags that represent flags (array of strings) OPTIONAL. A set of flags that represent
attributes or behaviors of the access token issued by the AS. attributes or behaviors of the access token issued by the AS.
The values of the "flags" field defined by this specification are as The values of the flags field defined by this specification are as
follows: follows:
"bearer" This flag indicates whether the token is bound to the "bearer" This flag indicates whether the token is a bearer token,
client instance's key. If the "bearer" flag is present, the not bound to a key and proofing mechanism. If the bearer flag is
access token is a bearer token, and the "key" field in this present, the access token is a bearer token, and the key field in
response MUST be omitted. If the "bearer" flag is omitted and the this response MUST be omitted. If the bearer flag is omitted and
"key" field in this response is omitted, the token is bound the the key field in this response is omitted, the token is bound the
key used by the client instance (Section 2.3) in its request for key used by the client instance (Section 2.3) in its request for
access. If the "bearer" flag is omitted, and the "key" field is access. If the bearer flag is omitted, and the key field is
present, the token is bound to the key and proofing mechanism present, the token is bound to the key and proofing mechanism
indicated in the "key" field. indicated in the key field. See Section 12.7 for additional
considerations on the use of bearer tokens.
"durable" OPTIONAL. Flag indicating a hint of AS behavior on token "durable" OPTIONAL. Flag indicating a hint of AS behavior on token
rotation. If this flag is present, then the client instance can rotation. If this flag is present, then the client instance can
expect a previously-issued access token to continue to work after expect a previously-issued access token to continue to work after
it has been rotated (Section 6.1) or the underlying grant request it has been rotated (Section 6.1) or the underlying grant request
has been modified (Section 5.3), resulting in the issuance of new has been modified (Section 5.3), resulting in the issuance of new
access tokens. If this flag is omitted, the client instance can access tokens. If this flag is omitted, the client instance can
anticipate a given access token will stop working after token anticipate a given access token will stop working after token
rotation or grant request modification. Note that a token flagged rotation or grant request modification. Note that a token flagged
as "durable" can still expire or be revoked through any normal as durable can still expire or be revoked through any normal
means. means.
"split" OPTIONAL. Flag indicating that this token was generated by "split" OPTIONAL. Flag indicating that this token was generated by
issuing multiple access tokens in response to one of the client issuing multiple access tokens in response to one of the client
instance's token request (Section 2.1) objects. This behavior instance's token request (Section 2.1) objects. This behavior
MUST NOT be used unless the client instance has specifically MUST NOT be used unless the client instance has specifically
requested it by use of the "split" flag. requested it by use of the split flag.
Flag values MUST NOT be included more than once. Flag values MUST NOT be included more than once.
Additional flags can be defined by extensions using a registry TBD Additional flags can be defined by extensions using a registry TBD
(Section 11). (Section 11).
The following non-normative example shows a single access token bound The following non-normative example shows a single access token bound
to the client instance's key used in the initial request, with a to the client instance's key used in the initial request, with a
management URL, and that has access to three described resources (one management URL, and that has access to three described resources (one
using an object and two described by reference strings). using an object and two described by reference strings).
skipping to change at page 50, line 45 skipping to change at page 51, line 45
"access_token": { "access_token": {
"value": "OS9M2PMHKUR64TB8N6BW7OZB8CDFONP219RP1LT0", "value": "OS9M2PMHKUR64TB8N6BW7OZB8CDFONP219RP1LT0",
"flags": ["bearer"], "flags": ["bearer"],
"access": [ "access": [
"finance", "medical" "finance", "medical"
] ]
} }
If the client instance requested a single access token If the client instance requested a single access token
(Section 2.1.1), the AS MUST NOT respond with the multiple access (Section 2.1.1), the AS MUST NOT respond with the multiple access
token structure unless the client instance sends the "split" flag as token structure unless the client instance sends the split flag as
described in Section 2.1.1. described in Section 2.1.1.
If the AS has split the access token response, the response MUST If the AS has split the access token response, the response MUST
include the "split" flag. include the split flag.
[[ See issue #69 (https://github.com/ietf-wg-gnap/gnap-core-protocol/ [[ See issue #69 (https://github.com/ietf-wg-gnap/gnap-core-protocol/
issues/69) ]] issues/69) ]]
3.2.2. Multiple Access Tokens 3.2.2. Multiple Access Tokens
If the client instance has requested multiple access tokens and the If the client instance has requested multiple access tokens and the
AS has granted at least one of them, the AS responds with the AS has granted at least one of them, the AS responds with the
"access_token" field. The value of this field is a JSON array, the "access_token" field. The value of this field is a JSON array, the
members of which are distinct access tokens as described in members of which are distinct access tokens as described in
Section 3.2.1. Each object MUST have a unique "label" field, Section 3.2.1. Each object MUST have a unique label field,
corresponding to the token labels chosen by the client instance in corresponding to the token labels chosen by the client instance in
the multiple access token request (Section 2.1.2). the multiple access token request (Section 2.1.2).
In this non-normative example, two tokens are issued under the names In this non-normative example, two tokens are issued under the names
"token1" and "token2", and only the first token has a management URL token1 and token2, and only the first token has a management URL
associated with it. associated with it.
NOTE: '\' line wrapping per RFC 8792 NOTE: '\' line wrapping per RFC 8792
"access_token": [ "access_token": [
{ {
"label": "token1", "label": "token1",
"value": "OS9M2PMHKUR64TB8N6BW7OZB8CDFONP219RP1LT0", "value": "OS9M2PMHKUR64TB8N6BW7OZB8CDFONP219RP1LT0",
"manage": "https://server.example.com/token/PRY5NM33O\ "manage": "https://server.example.com/token/PRY5NM33O\
M4TB8N6BW7OZB8CDFONP219RP1L", M4TB8N6BW7OZB8CDFONP219RP1L",
"access": [ "finance" ] "access": [ "finance" ]
}, },
{ {
"label": "token2", "label": "token2",
"value": "UFGLO2FDAFG7VGZZPJ3IZEMN21EVU71FHCARP4J1", "value": "UFGLO2FDAFG7VGZZPJ3IZEMN21EVU71FHCARP4J1",
"access": [ "medical" ] "access": [ "medical" ]
} }
} }
Each access token corresponds to one of the objects in the Each access token corresponds to one of the objects in the
"access_token" array of the client instance's request access_token array of the client instance's request (Section 2.1.2).
(Section 2.1.2).
The multiple access token response MUST be used when multiple access The multiple access token response MUST be used when multiple access
tokens are requested, even if only one access token is issued as a tokens are requested, even if only one access token is issued as a
result of the request. The AS MAY refuse to issue one or more of the result of the request. The AS MAY refuse to issue one or more of the
requested access tokens, for any reason. In such cases the refused requested access tokens, for any reason. In such cases the refused
token is omitted from the response and all of the other issued access token is omitted from the response and all of the other issued access
tokens are included in the response the requested names appropriate tokens are included in the response the requested names appropriate
names. names.
If the client instance requested multiple access tokens If the client instance requested multiple access tokens
(Section 2.1.2), the AS MUST NOT respond with a single access token (Section 2.1.2), the AS MUST NOT respond with a single access token
structure, even if only a single access token is granted. In such structure, even if only a single access token is granted. In such
cases, the AS responds with a multiple access token structure cases, the AS responds with a multiple access token structure
containing one access token. containing one access token.
If the AS has split the access token response, the response MUST If the AS has split the access token response, the response MUST
include the "split" flag in the "flags" array. include the split flag in the flags array.
"access_token": [ "access_token": [
{ {
"label": "split-1", "label": "split-1",
"value": "8N6BW7OZB8CDFONP219-OS9M2PMHKUR64TBRP1LT0", "value": "8N6BW7OZB8CDFONP219-OS9M2PMHKUR64TBRP1LT0",
"flags": ["split"], "flags": ["split"],
"manage": "https://server.example.com/token/PRY5NM33O\ "manage": "https://server.example.com/token/PRY5NM33O\
M4TB8N6BW7OZB8CDFONP219RP1L", M4TB8N6BW7OZB8CDFONP219RP1L",
"access": [ "fruits" ] "access": [ "fruits" ]
}, },
skipping to change at page 52, line 29 skipping to change at page 53, line 29
"value": "FG7VGZZPJ3IZEMN21EVU71FHCAR-UFGLO2FDAP4J1", "value": "FG7VGZZPJ3IZEMN21EVU71FHCAR-UFGLO2FDAP4J1",
"flags": ["split"], "flags": ["split"],
"access": [ "vegetables" ] "access": [ "vegetables" ]
} }
} }
Each access token MAY be bound to different keys with different Each access token MAY be bound to different keys with different
proofing mechanisms. proofing mechanisms.
If token management (Section 6) is allowed, each access token SHOULD If token management (Section 6) is allowed, each access token SHOULD
have different "manage" URIs. have different manage URIs.
[[ See issue #70 (https://github.com/ietf-wg-gnap/gnap-core-protocol/ [[ See issue #70 (https://github.com/ietf-wg-gnap/gnap-core-protocol/
issues/70) ]] issues/70) ]]
3.3. Interaction Modes 3.3. Interaction Modes
If the client instance has indicated a capability to interact with If the client instance has indicated a capability to interact with
the RO in its request (Section 2.5), and the AS has determined that the RO in its request (Section 2.5), and the AS has determined that
interaction is both supported and necessary, the AS responds to the interaction is both supported and necessary, the AS responds to the
client instance with any of the following values in the "interact" client instance with any of the following values in the interact
field of the response. There is no preference order for interaction field of the response. There is no preference order for interaction
modes in the response, and it is up to the client instance to modes in the response, and it is up to the client instance to
determine which ones to use. All supported interaction methods are determine which ones to use. All supported interaction methods are
included in the same "interact" object. included in the same interact object.
redirect (string) Redirect to an arbitrary URL. Section 3.3.1 redirect (string) Redirect to an arbitrary URL. Section 3.3.1
app (string) Launch of an application URL. Section 3.3.2 app (string) Launch of an application URL. Section 3.3.2
finish (string) A nonce used by the client instance to verify the finish (string) A nonce used by the client instance to verify the
callback after interaction is completed. Section 3.3.4 callback after interaction is completed. Section 3.3.4
user_code (object) Display a short user code. Section 3.3.3 user_code (object) Display a short user code. Section 3.3.3
Additional interaction mode responses can be defined in a registry Additional interaction mode responses can be defined in a registry
skipping to change at page 55, line 49 skipping to change at page 56, line 49
See details of the interaction in Section 4.1.2. See details of the interaction in Section 4.1.2.
[[ See issue #72 (https://github.com/ietf-wg-gnap/gnap-core-protocol/ [[ See issue #72 (https://github.com/ietf-wg-gnap/gnap-core-protocol/
issues/72) ]] issues/72) ]]
3.3.4. Interaction Finish 3.3.4. Interaction Finish
If the client instance indicates that it can receive a If the client instance indicates that it can receive a
post-interaction redirect or push at a URL (Section 2.5.2) and the AS post-interaction redirect or push at a URL (Section 2.5.2) and the AS
supports this mode for the client instance's request, the AS responds supports this mode for the client instance's request, the AS responds
with a "finish" field containing a nonce that the client instance with a finish field containing a nonce that the client instance will
will use in validating the callback as defined in Section 4.2. use in validating the callback as defined in Section 4.2.
"interact": { "interact": {
"finish": "MBDOFXG4Y5CVJCX821LH" "finish": "MBDOFXG4Y5CVJCX821LH"
} }
When the interaction is completed, the interaction component MUST When the interaction is completed, the interaction component MUST
contact the client instance using either a redirect or launch of the contact the client instance using either a redirect or launch of the
RO's browser or through an HTTP POST to the client instance's RO's browser or through an HTTP POST to the client instance's
callback URL using the method indicated in the interaction request callback URL using the method indicated in the interaction request
(Section 2.5.2) as described in Section 4.2. (Section 2.5.2) as described in Section 4.2.
skipping to change at page 56, line 29 skipping to change at page 57, line 29
3.3.5. Extending Interaction Mode Responses 3.3.5. Extending Interaction Mode Responses
Extensions to this specification can define new interaction mode Extensions to this specification can define new interaction mode
responses in a registry TBD (Section 11). Extensions MUST document responses in a registry TBD (Section 11). Extensions MUST document
the corresponding interaction request. the corresponding interaction request.
3.4. Returning Subject Information 3.4. Returning Subject Information
If information about the RO is requested and the AS grants the client If information about the RO is requested and the AS grants the client
instance access to that data, the AS returns the approved information instance access to that data, the AS returns the approved information
in the "subject" response field. The AS MUST return the "subject" in the "subject" response field. The AS MUST return the subject
field only in cases where the AS is sure that the RO and the end-user field only in cases where the AS is sure that the RO and the end-user
are the same party. This can be accomplished through some forms of are the same party. This can be accomplished through some forms of
interaction with the RO (Section 4). interaction with the RO (Section 4).
This field is an object with the following OPTIONAL properties. This field is an object with the following OPTIONAL properties.
sub_ids (array of objects) An array of subject identifiers for the sub_ids (array of objects) An array of subject identifiers for the
RO, as defined by [I-D.ietf-secevent-subject-identifiers]. RO, as defined by [I-D.ietf-secevent-subject-identifiers].
assertions (object) An object containing assertions as values keyed An object containing assertions as values keyed on the assertion
on the assertion type defined by a registry TBD (Section 11). [[ type defined by a registry TBD (Section 11). Possible keys
include id_token for an [OIDC] ID Token and saml2 for a SAML 2
assertion. The assertion values are the string serialization of
the assertion format, encoded as a plain JSON string. Additional
assertion types are defined by a registry TBD (Section 11). [[
See issue #41 (https://github.com/ietf-wg-gnap/gnap-core-protocol/ See issue #41 (https://github.com/ietf-wg-gnap/gnap-core-protocol/
issues/41) ]] issues/41) ]]
updated_at (string) Timestamp as an ISO8610 date string, indicating updated_at (string) Timestamp as an ISO8610 date string, indicating
when the identified account was last updated. The client instance when the identified account was last updated. The client instance
MAY use this value to determine if it needs to request updated MAY use this value to determine if it needs to request updated
profile information through an identity API. The definition of profile information through an identity API. The definition of
such an identity API is out of scope for this specification. such an identity API is out of scope for this specification.
"subject": { "subject": {
skipping to change at page 57, line 37 skipping to change at page 58, line 37
represented email address or phone number in the identifier is represented email address or phone number in the identifier is
suitable for communication with the current user. To get such suitable for communication with the current user. To get such
information, the client instance MUST use an identity protocol to information, the client instance MUST use an identity protocol to
request and receive additional identity claims. The details of an request and receive additional identity claims. The details of an
identity protocol and associated schema are outside the scope of this identity protocol and associated schema are outside the scope of this
specification. specification.
Extensions to this specification MAY define additional response Extensions to this specification MAY define additional response
properties in a registry TBD (Section 11). properties in a registry TBD (Section 11).
3.5. Returning Dynamically-bound Reference Handles See Section 12.25 for considerations that the client instance has to
make when accepting and processing assertions from the AS.
3.5. Returning a Dynamically-bound Client Instance Identifier
Many parts of the client instance's request can be passed as either a Many parts of the client instance's request can be passed as either a
value or a reference. The use of a reference in place of a value value or a reference. The use of a reference in place of a value
allows for a client instance to optimize requests to the AS. allows for a client instance to optimize requests to the AS.
Some references, such as for the client instance's identity Some references, such as for the client instance's identity
(Section 2.3.1) or the requested resources (Section 8.1), can be (Section 2.3.1) or the requested resources (Section 8.1), can be
managed statically through an admin console or developer portal managed statically through an admin console or developer portal
provided by the AS or RS. The developer of the client software can provided by the AS or RS. The developer of the client software can
include these values in their code for a more efficient and compact include these values in their code for a more efficient and compact
request. request.
If desired, the AS MAY also generate and return some of these If desired, the AS MAY also generate and return an instance
references dynamically to the client instance in its response to identifier dynamically to the client instance in the response to
facilitate multiple interactions with the same software. The client facilitate multiple interactions with the same client instance over
instance SHOULD use these references in future requests in lieu of time. The client instance SHOULD use this instance identifier in
sending the associated data value. These handles are intended to be future requests in lieu of sending the associated data values in the
used on future requests. client field.
Dynamically generated handles are string values that MUST be
protected by the client instance as secrets. Handle values MUST be
unguessable and MUST NOT contain any sensitive information. Handle
values are opaque to the client instance.
All dynamically generated handles are returned as fields in the root Dynamically generated client instance identifiers are string values
JSON object of the response. This specification defines the that MUST be protected by the client instance as secrets. Instance
following dynamic handle return, additional handles can be defined in identifier values MUST be unguessable and MUST NOT contain any
a registry TBD (Section 11). sensitive information. Instance identifier values are opaque to the
client instance.
instance_id (string) A string value used to represent the instance_id (string) A string value used to represent the
information in the "client" object that the client instance can information in the client object that the client instance can use
use in a future request, as described in Section 2.3.1. in a future request, as described in Section 2.3.1.
This non-normative example shows one handle along side an issued This non-normative example shows an instance identifier along side an
access token. issued access token.
{ {
"instance_id": "7C7C4AZ9KHRS6X63AJAO", "instance_id": "7C7C4AZ9KHRS6X63AJAO",
"access_token": { "access_token": {
"value": "OS9M2PMHKUR64TB8N6BW7OZB8CDFONP219RP1LT0" "value": "OS9M2PMHKUR64TB8N6BW7OZB8CDFONP219RP1LT0"
} }
} }
[[ See issue #77 (https://github.com/ietf-wg-gnap/gnap-core-protocol/ [[ See issue #77 (https://github.com/ietf-wg-gnap/gnap-core-protocol/
issues/77) ]] issues/77) ]]
skipping to change at page 59, line 25 skipping to change at page 60, line 23
[[ See issue #79 (https://github.com/ietf-wg-gnap/gnap-core-protocol/ [[ See issue #79 (https://github.com/ietf-wg-gnap/gnap-core-protocol/
issues/79) ]] issues/79) ]]
3.7. Extending the Response 3.7. Extending the Response
Extensions to this specification MAY define additional fields for the Extensions to this specification MAY define additional fields for the
grant response in a registry TBD (Section 11). grant response in a registry TBD (Section 11).
4. Determining Authorization and Consent 4. Determining Authorization and Consent
When the client instance makes its Section 2 to the AS for delegated When the client instance makes its initial request (Section 2) to the
access, it is capable of asking for several different kinds of AS for delegated access, it is capable of asking for several
information in response: different kinds of information in response:
* the access being requested in the "access_token" request parameter * the access being requested in the access_token request parameter
* the subject information being requested in the "subject" request * the subject information being requested in the subject request
parameter parameter
* any additional requested information defined by extensions of this * any additional requested information defined by extensions of this
protocol protocol
The AS determines what authorizations and consents are required to The AS determines what authorizations and consents are required to
fulfill this requested delegation. The details of how the AS makes fulfill this requested delegation. The details of how the AS makes
this determination are out of scope for this document. However, this determination are out of scope for this document. However,
there are several common patterns defined and supported by GNAP for there are several common patterns defined and supported by GNAP for
fulfilling these requirements, including information sent by the fulfilling these requirements, including information sent by the
skipping to change at page 60, line 8 skipping to change at page 61, line 5
how to gather the necessary authorizations and consent. how to gather the necessary authorizations and consent.
The client instance can supply information directly to the AS in its The client instance can supply information directly to the AS in its
request. From this information, the AS can determine if the request. From this information, the AS can determine if the
requested delegation can be granted immediately. The client instance requested delegation can be granted immediately. The client instance
can send several kinds of things, including: can send several kinds of things, including:
* the identity of the client instance, known from the presented keys * the identity of the client instance, known from the presented keys
or associated identifiers or associated identifiers
* the identity of the end user presented in the "user" request * the identity of the end user presented in the user request
parameter parameter
* any additional information presented by the client instance in the * any additional information presented by the client instance in the
request, including any extensions request, including any extensions
The AS will verify this presented information in the context of the The AS will verify this presented information in the context of the
client instance's request and can only trust the information as much client instance's request and can only trust the information as much
as it trusts the presentation and context of the information. If the as it trusts the presentation and context of the information. If the
AS determines that the information presented in the initial request AS determines that the information presented in the initial request
is sufficient for granting the requested access, the AS MAY return is sufficient for granting the requested access, the AS MAY return
the positive results immediately in its Section 3 with access tokens the positive results immediately in its response (Section 3) with
and subject information. access tokens and subject information.
If the AS determines that additional runtime authorization is If the AS determines that additional runtime authorization is
required, the AS can either deny the request outright or use a number required, the AS can either deny the request outright or use a number
of means at its disposal to gather that authorization from the of means at its disposal to gather that authorization from the
appropriate ROs, including for example: appropriate ROs, including for example:
* starting interaction with the end user facilitated by the client * starting interaction with the end user facilitated by the client
software, such as a redirection or user code software, such as a redirection or user code
* challenging the client instance through a challenge-response * challenging the client instance through a challenge-response
skipping to change at page 65, line 16 skipping to change at page 66, line 23
method are dangerous or blocked. method are dangerous or blocked.
* The AS cannot determine which ongoing grant request is being * The AS cannot determine which ongoing grant request is being
referenced. referenced.
* The ongoing grant request has been cancelled or otherwise blocked. * The ongoing grant request has been cancelled or otherwise blocked.
4.2.1. Completing Interaction with a Browser Redirect to the Callback 4.2.1. Completing Interaction with a Browser Redirect to the Callback
URI URI
When using the "redirect" interaction finish method (Section 3.3.4), When using the redirect interaction finish method (Section 3.3.4),
the AS signals to the client instance that interaction is complete the AS signals to the client instance that interaction is complete
and the request can be continued by directing the RO (in their and the request can be continued by directing the RO (in their
browser) back to the client instance's redirect URL sent in the browser) back to the client instance's redirect URL sent in the
callback request (Section 2.5.2.1). callback request (Section 2.5.2.1).
The AS secures this redirect by adding the hash and interaction The AS secures this redirect by adding the hash and interaction
reference as query parameters to the client instance's redirect URL. reference as query parameters to the client instance's redirect URL.
hash REQUIRED. The interaction hash value as described in hash REQUIRED. The interaction hash value as described in
Section 4.2.3. Section 4.2.3.
skipping to change at page 66, line 7 skipping to change at page 67, line 13
&interact_ref=4IFWWIKYBC2PQ6U56NL1 &interact_ref=4IFWWIKYBC2PQ6U56NL1
When receiving the request, the client instance MUST parse the query When receiving the request, the client instance MUST parse the query
parameters to calculate and validate the hash value as described in parameters to calculate and validate the hash value as described in
Section 4.2.3. If the hash validates, the client instance sends a Section 4.2.3. If the hash validates, the client instance sends a
continuation request to the AS as described in Section 5.1 using the continuation request to the AS as described in Section 5.1 using the
interaction reference value received here. interaction reference value received here.
4.2.2. Completing Interaction with a Direct HTTP Request Callback 4.2.2. Completing Interaction with a Direct HTTP Request Callback
When using the "callback" interaction mode (Section 3.3.4) with the When using the push interaction finish method (Section 3.3.4), the AS
"push" method, the AS signals to the client instance that interaction signals to the client instance that interaction is complete and the
is complete and the request can be continued by sending an HTTP POST request can be continued by sending an HTTP POST request to the
request to the client instance's callback URL sent in the callback client instance's callback URL sent in the callback request
request (Section 2.5.2.2). (Section 2.5.2.2).
The entity message body is a JSON object consisting of the following The entity message body is a JSON object consisting of the following
two fields: two fields:
hash (string) REQUIRED. The interaction hash value as described in hash (string) REQUIRED. The interaction hash value as described in
Section 4.2.3. Section 4.2.3.
interact_ref (string) REQUIRED. The interaction reference generated interact_ref (string) REQUIRED. The interaction reference generated
for this interaction. for this interaction.
skipping to change at page 67, line 7 skipping to change at page 68, line 17
The "hash" parameter in the request to the client instance's callback The "hash" parameter in the request to the client instance's callback
URL ties the front channel response to an ongoing request by using URL ties the front channel response to an ongoing request by using
values known only to the parties involved. This security mechanism values known only to the parties involved. This security mechanism
allows the client instance to protect itself against several kinds of allows the client instance to protect itself against several kinds of
session fixation and injection attacks. The AS MUST always provide session fixation and injection attacks. The AS MUST always provide
this hash, and the client instance MUST validate the hash when this hash, and the client instance MUST validate the hash when
received. received.
To calculate the "hash" value, the party doing the calculation To calculate the "hash" value, the party doing the calculation
creates a hash string by concatenating the following values in the creates a hash string by concatenating the following values in the
following order using a single newline ("\\n") character to separate following order using a single newline (\n) character to separate
them: them:
* the "nonce" value sent by the client instance in the interaction * the "nonce" value sent by the client instance in the interaction
"finish" section of the initial request (Section 2.5.2) "finish" section of the initial request (Section 2.5.2)
* the AS's nonce value from the interaction finish response * the AS's nonce value from the interaction finish response
(Section 3.3.4) (Section 3.3.4)
* the "interact_ref" returned from the AS as part of the interaction * the "interact_ref" returned from the AS as part of the interaction
finish method (Section 4.2) finish method (Section 4.2)
skipping to change at page 67, line 31 skipping to change at page 68, line 41
There is no padding or whitespace before or after any of the lines, There is no padding or whitespace before or after any of the lines,
and no trailing newline character. and no trailing newline character.
VJLO6A4CAYLBXHTR0KRO VJLO6A4CAYLBXHTR0KRO
MBDOFXG4Y5CVJCX821LH MBDOFXG4Y5CVJCX821LH
4IFWWIKYBC2PQ6U56NL1 4IFWWIKYBC2PQ6U56NL1
https://server.example.com/tx https://server.example.com/tx
The party then hashes this string with the appropriate algorithm The party then hashes this string with the appropriate algorithm
based on the "hash_method" parameter of the "callback". If the based on the "hash_method" parameter under the "finish" key. If the
"hash_method" value is not present in the client instance's request, "hash_method" value is not present in the client instance's request,
the algorithm defaults to "sha3". the algorithm defaults to "sha3".
[[ See issue #56 (https://github.com/ietf-wg-gnap/gnap-core-protocol/ [[ See issue #56 (https://github.com/ietf-wg-gnap/gnap-core-protocol/
issues/56) ]] issues/56) ]]
4.2.3.1. SHA3-512 4.2.3.1. SHA3-512
The "sha3" hash method consists of hashing the input string with the The "sha3" hash method consists of hashing the input string with the
512-bit SHA3 algorithm. The byte array is then encoded using URL 512-bit SHA3 algorithm. The byte array is then encoded using URL
skipping to change at page 68, line 18 skipping to change at page 69, line 23
512-bit SHA2 algorithm. The byte array is then encoded using URL 512-bit SHA2 algorithm. The byte array is then encoded using URL
Safe Base64 with no padding. The resulting string is the hash value. Safe Base64 with no padding. The resulting string is the hash value.
NOTE: '\' line wrapping per RFC 8792 NOTE: '\' line wrapping per RFC 8792
62SbcD3Xs7L40rjgALA-ymQujoh2LB2hPJyX9vlcr1H6ecChZ8BNKkG_HrOKP_Bp\ 62SbcD3Xs7L40rjgALA-ymQujoh2LB2hPJyX9vlcr1H6ecChZ8BNKkG_HrOKP_Bp\
j84rh4mC9aE9x7HPBFcIHw j84rh4mC9aE9x7HPBFcIHw
5. Continuing a Grant Request 5. Continuing a Grant Request
While it is possible for the AS to return a Section 3 with all the While it is possible for the AS to return a grant response
client instance's requested information (including access tokens (Section 3) with all the client instance's requested information
(Section 3.2) and direct user information (Section 3.4)), it's more (including access tokens (Section 3.2) and direct user information
common that the AS and the client instance will need to communicate (Section 3.4)), it's more common that the AS and the client instance
several times over the lifetime of an access grant. This is often will need to communicate several times over the lifetime of an access
part of facilitating interaction (Section 4), but it could also be grant. This is often part of facilitating interaction (Section 4),
used to allow the AS and client instance to continue negotiating the but it could also be used to allow the AS and client instance to
parameters of the original grant request (Section 2). continue negotiating the parameters of the original grant request
(Section 2).
To enable this ongoing negotiation, the AS provides a continuation To enable this ongoing negotiation, the AS provides a continuation
API to the client software. The AS returns a "continue" field in the API to the client software. The AS returns a continue field in the
response (Section 3.1) that contains information the client instance response (Section 3.1) that contains information the client instance
needs to access this API, including a URI to access as well as an needs to access this API, including a URI to access as well as a
access token to use during the continued requests. continuation access token to use during the requests.
The access token is initially bound to the same key and method the The continuation access token is initially bound to the same key and
client instance used to make the initial request. As a consequence, method the client instance used to make the initial request. As a
when the client instance makes any calls to the continuation URL, the consequence, when the client instance makes any calls to the
client instance MUST present the access token as described in continuation URL, the client instance MUST present the continuation
Section 7.2 and present proof of the client instance's key (or its access token as described in Section 7.2 and present proof of the
most recent rotation) by signing the request as described in client instance's key (or its most recent rotation) by signing the
Section 7.3. The AS MUST validate all keys presented by the client request as described in Section 7.3. The AS MUST validate all keys
instance or referenced in an ongoing request for each call within presented by the client instance or referenced in an ongoing request
that request. for each call within that request.
Access tokens other than the continuation access tokens MUST NOT be
usable for continuation requests.
[[ See issue #85 (https://github.com/ietf-wg-gnap/gnap-core-protocol/ [[ See issue #85 (https://github.com/ietf-wg-gnap/gnap-core-protocol/
issues/85) ]] issues/85) ]]
For example, here the client instance makes a POST request to a For example, here the client instance makes a POST request to a
unique URI and signs the request with HTTP Message Signatures: unique URI and signs the request with HTTP Message Signatures:
POST /continue/KSKUOMUKM HTTP/1.1 POST /continue/KSKUOMUKM HTTP/1.1
Authorization: GNAP 80UPRY5NM33OMUKMKSKU Authorization: GNAP 80UPRY5NM33OMUKMKSKU
Host: server.example.com Host: server.example.com
Signature-Input: sig1=... Signature-Input: sig1=...
Signature: sig1=... Signature: sig1=...
The AS MUST be able to tell from the client instance's request which The AS MUST be able to tell from the client instance's request which
specific ongoing request is being accessed, using a combination of specific ongoing request is being accessed, using a combination of
the continuation URL, the provided access token, and the client the continuation URL, the provided continuation access token, and the
instance identified by the key signature. If the AS cannot determine client instance identified by the key signature. If the AS cannot
a single active grant request to map the continuation request to, the determine a single active grant request to map the continuation
AS MUST return an error. request to, the AS MUST return an error.
The ability to continue an already-started request allows the client The ability to continue an already-started request allows the client
instance to perform several important functions, including presenting instance to perform several important functions, including presenting
additional information from interaction, modifying the initial additional information from interaction, modifying the initial
request, and getting the current state of the request. request, and getting the current state of the request.
All requests to the continuation API are protected by this bound All requests to the continuation API are protected by this bound
access token. For example, here the client instance makes a POST continuation access token. For example, here the client instance
request to a stable continuation endpoint URL with the interaction makes a POST request to a stable continuation endpoint URL with the
reference (Section 5.1), includes the access token, and signs with interaction reference (Section 5.1), includes the access token, and
HTTP Message Signatures: signs with HTTP Message Signatures:
POST /continue HTTP/1.1 POST /continue HTTP/1.1
Host: server.example.com Host: server.example.com
Content-Type: application/json Content-Type: application/json
Authorization: GNAP 80UPRY5NM33OMUKMKSKU Authorization: GNAP 80UPRY5NM33OMUKMKSKU
Signature-Input: sig1=... Signature-Input: sig1=...
Signature: sig1=... Signature: sig1=...
Digest: sha256=... Digest: sha256=...
{ {
"interact_ref": "4IFWWIKYBC2PQ6U56NL1" "interact_ref": "4IFWWIKYBC2PQ6U56NL1"
} }
If a "wait" parameter was included in the continuation response If a wait parameter was included in the continuation response
(Section 3.1), the client instance MUST NOT call the continuation URI (Section 3.1), the client instance MUST NOT call the continuation URI
prior to waiting the number of seconds indicated. If no "wait" prior to waiting the number of seconds indicated. If no wait period
period is indicated, the client instance SHOULD wait at least 5 is indicated, the client instance SHOULD wait at least 5 seconds. If
seconds. If the client instance does not respect the given wait the client instance does not respect the given wait period, the AS
period, the AS MUST return an error. [[ See issue #86 MUST return an error.
(https://github.com/ietf-wg-gnap/gnap-core-protocol/issues/86) ]]
The response from the AS is a JSON object and MAY contain any of the The response from the AS is a JSON object and MAY contain any of the
fields described in Section 3, as described in more detail in the fields described in Section 3, as described in more detail in the
sections below. sections below.
If the AS determines that the client instance can make a further If the AS determines that the client instance can make a further
continuation request, the AS MUST include a new "continue" response continuation request, the AS MUST include a new "continue" response
(Section 3.1). The new "continue" response MUST include a bound (Section 3.1). The new continue response MUST include a continuation
access token as well, and this token SHOULD be a new access token, access token as well, and this token SHOULD be a new access token,
invalidating the previous access token. If the AS does not return a invalidating the previous access token. If the AS does not return a
new "continue" response, the client instance MUST NOT make an new continue response, the client instance MUST NOT make an
additional continuation request. If a client instance does so, the additional continuation request. If a client instance does so, the
AS MUST return an error. [[ See issue #87 (https://github.com/ietf- AS MUST return an error. [[ See issue #87 (https://github.com/ietf-
wg-gnap/gnap-core-protocol/issues/87) ]] wg-gnap/gnap-core-protocol/issues/87) ]]
For continuation functions that require the client instance to send a For continuation functions that require the client instance to send a
message body, the body MUST be a JSON object. message body, the body MUST be a JSON object.
5.1. Continuing After a Completed Interaction 5.1. Continuing After a Completed Interaction
When the AS responds to the client instance's "finish" method as in When the AS responds to the client instance's finish method as in
Section 4.2.1, this response includes an interaction reference. The Section 4.2.1, this response includes an interaction reference. The
client instance MUST include that value as the field "interact_ref" client instance MUST include that value as the field interact_ref in
in a POST request to the continuation URI. a POST request to the continuation URI.
POST /continue HTTP/1.1 POST /continue HTTP/1.1
Host: server.example.com Host: server.example.com
Content-Type: application/json Content-Type: application/json
Authorization: GNAP 80UPRY5NM33OMUKMKSKU Authorization: GNAP 80UPRY5NM33OMUKMKSKU
Signature-Input: sig1=... Signature-Input: sig1=...
Signature: sig1=... Signature: sig1=...
Digest: sha256=... Digest: sha256=...
{ {
skipping to change at page 70, line 45 skipping to change at page 72, line 5
} }
Since the interaction reference is a one-time-use value as described Since the interaction reference is a one-time-use value as described
in Section 4.2.1, if the client instance needs to make additional in Section 4.2.1, if the client instance needs to make additional
continuation calls after this request, the client instance MUST NOT continuation calls after this request, the client instance MUST NOT
include the interaction reference. If the AS detects a client include the interaction reference. If the AS detects a client
instance submitting the same interaction reference multiple times, instance submitting the same interaction reference multiple times,
the AS MUST return an error and SHOULD invalidate the ongoing the AS MUST return an error and SHOULD invalidate the ongoing
request. request.
The Section 3 MAY contain any newly-created access tokens The grant response (Section 3) MAY contain any newly-created access
(Section 3.2) or newly-released subject claims (Section 3.4). The tokens (Section 3.2) or newly-released subject claims (Section 3.4).
response MAY contain a new "continue" response (Section 3.1) as The response MAY contain a new "continue" response (Section 3.1) as
described above. The response SHOULD NOT contain any interaction described above. The response SHOULD NOT contain any interaction
responses (Section 3.3). [[ See issue #89 (https://github.com/ietf- responses (Section 3.3). [[ See issue #89 (https://github.com/ietf-
wg-gnap/gnap-core-protocol/issues/89) ]] wg-gnap/gnap-core-protocol/issues/89) ]]
For example, if the request is successful in causing the AS to issue For example, if the request is successful in causing the AS to issue
access tokens and release opaque subject claims, the response could access tokens and release opaque subject claims, the response could
look like this: look like this:
NOTE: '\' line wrapping per RFC 8792 NOTE: '\' line wrapping per RFC 8792
{ {
"access_token": { "access_token": {
"value": "OS9M2PMHKUR64TB8N6BW7OZB8CDFONP219RP1LT0", "value": "OS9M2PMHKUR64TB8N6BW7OZB8CDFONP219RP1LT0",
"manage": "https://server.example.com/token/PRY5NM33O\ "manage": "https://server.example.com/token/PRY5NM33O\
skipping to change at page 71, line 25 skipping to change at page 72, line 33
}, },
"subject": { "subject": {
"sub_ids": [ { "sub_ids": [ {
"format": "opaque", "format": "opaque",
"id": "J2G8G8O4AZ" "id": "J2G8G8O4AZ"
} ] } ]
} }
} }
With this example, the client instance can not make an additional With this example, the client instance can not make an additional
continuation request because a "continue" field is not included. continuation request because a continue field is not included.
[[ See issue #88 (https://github.com/ietf-wg-gnap/gnap-core-protocol/ [[ See issue #88 (https://github.com/ietf-wg-gnap/gnap-core-protocol/
issues/88) ]] issues/88) ]]
5.2. Continuing During Pending Interaction 5.2. Continuing During Pending Interaction
When the client instance does not include a "finish" parameter, the When the client instance does not include a finish parameter, the
client instance will often need to poll the AS until the RO has client instance will often need to poll the AS until the RO has
authorized the request. To do so, the client instance makes a POST authorized the request. To do so, the client instance makes a POST
request to the continuation URI as in Section 5.1, but does not request to the continuation URI as in Section 5.1, but does not
include a message body. include a message body.
POST /continue HTTP/1.1 POST /continue HTTP/1.1
Host: server.example.com Host: server.example.com
Content-Type: application/json Content-Type: application/json
Authorization: GNAP 80UPRY5NM33OMUKMKSKU Authorization: GNAP 80UPRY5NM33OMUKMKSKU
Signature-Input: sig1=... Signature-Input: sig1=...
Signature: sig1=... Signature: sig1=...
The Section 3 MAY contain any newly-created access tokens The grant response (Section 3) MAY contain any newly-created access
(Section 3.2) or newly-released subject claims (Section 3.4). The tokens (Section 3.2) or newly-released subject claims (Section 3.4).
response MAY contain a new "continue" response (Section 3.1) as The response MAY contain a new "continue" response (Section 3.1) as
described above. If a "continue" field is included, it SHOULD described above. If a continue field is included, it SHOULD include
include a "wait" field to facilitate a reasonable polling rate by the a wait field to facilitate a reasonable polling rate by the client
client instance. The response SHOULD NOT contain interaction instance. The response SHOULD NOT contain interaction responses
responses (Section 3.3). (Section 3.3).
For example, if the request has not yet been authorized by the RO, For example, if the request has not yet been authorized by the RO,
the AS could respond by telling the client instance to make another the AS could respond by telling the client instance to make another
continuation request in the future. In this example, a new, unique continuation request in the future. In this example, a new, unique
access token has been issued for the call, which the client instance access token has been issued for the call, which the client instance
will use in its next continuation request. will use in its next continuation request.
{ {
"continue": { "continue": {
"access_token": { "access_token": {
skipping to change at page 73, line 5 skipping to change at page 74, line 21
M4TB8N6BW7OZB8CDFONP219RP1L", M4TB8N6BW7OZB8CDFONP219RP1L",
}, },
"subject": { "subject": {
"sub_ids": [ { "sub_ids": [ {
"format": "opaque", "format": "opaque",
"id": "J2G8G8O4AZ" "id": "J2G8G8O4AZ"
} ] } ]
} }
} }
See Section 12.20 for considerations on polling for continuation
without an interaction finish method.
5.3. Modifying an Existing Request 5.3. Modifying an Existing Request
The client instance might need to modify an ongoing request, whether The client instance might need to modify an ongoing request, whether
or not tokens have already been issued or claims have already been or not tokens have already been issued or claims have already been
released. In such cases, the client instance makes an HTTP PATCH released. In such cases, the client instance makes an HTTP PATCH
request to the continuation URI and includes any fields it needs to request to the continuation URI and includes any fields it needs to
modify. Fields that aren't included in the request are considered modify. Fields that aren't included in the request are considered
unchanged from the original request. unchanged from the original request.
The client instance MAY include the "access_token" and "subject" The client instance MAY include the access_token and subject fields
fields as described in Section 2.1 and Section 2.2. Inclusion of as described in Section 2.1 and Section 2.2. Inclusion of these
these fields override any values in the initial request, which MAY fields override any values in the initial request, which MAY trigger
trigger additional requirements and policies by the AS. For example, additional requirements and policies by the AS. For example, if the
if the client instance is asking for more access, the AS could client instance is asking for more access, the AS could require
require additional interaction with the RO to gather additional additional interaction with the RO to gather additional consent. If
consent. If the client instance is asking for more limited access, the client instance is asking for more limited access, the AS could
the AS could determine that sufficient authorization has been granted determine that sufficient authorization has been granted to the
to the client instance and return the more limited access rights client instance and return the more limited access rights
immediately. [[ See issue #92 (https://github.com/ietf-wg-gnap/gnap- immediately. [[ See issue #92 (https://github.com/ietf-wg-gnap/gnap-
core-protocol/issues/92) ]] core-protocol/issues/92) ]]
The client instance MAY include the "interact" field as described in The client instance MAY include the interact field as described in
Section 2.5. Inclusion of this field indicates that the client Section 2.5. Inclusion of this field indicates that the client
instance is capable of driving interaction with the RO, and this instance is capable of driving interaction with the RO, and this
field replaces any values from a previous request. The AS MAY field replaces any values from a previous request. The AS MAY
respond to any of the interaction responses as described in respond to any of the interaction responses as described in
Section 3.3, just like it would to a new request. Section 3.3, just like it would to a new request.
The client instance MAY include the "user" field as described in The client instance MAY include the user field as described in
Section 2.4 to present new assertions or information about the end- Section 2.4 to present new assertions or information about the end-
user. [[ See issue #93 (https://github.com/ietf-wg-gnap/gnap-core- user. [[ See issue #93 (https://github.com/ietf-wg-gnap/gnap-core-
protocol/issues/93) ]] protocol/issues/93) ]]
The client instance MUST NOT include the "client" section of the The client instance MUST NOT include the client section of the
request. [[ See issue #94 (https://github.com/ietf-wg-gnap/gnap-core- request. [[ See issue #94 (https://github.com/ietf-wg-gnap/gnap-core-
protocol/issues/94) ]] protocol/issues/94) ]]
The client instance MAY include post-interaction responses such as The client instance MAY include post-interaction responses such as
described in Section 5.1. [[ See issue #95 (https://github.com/ietf- described in Section 5.1. [[ See issue #95 (https://github.com/ietf-
wg-gnap/gnap-core-protocol/issues/95) ]] wg-gnap/gnap-core-protocol/issues/95) ]]
Modification requests MUST NOT alter previously-issued access tokens. Modification requests MUST NOT alter previously-issued access tokens.
Instead, any access tokens issued from a continuation are considered Instead, any access tokens issued from a continuation are considered
new, separate access tokens. The AS MAY revoke existing access new, separate access tokens. The AS MAY revoke existing access
skipping to change at page 74, line 4 skipping to change at page 75, line 23
The client instance MAY include post-interaction responses such as The client instance MAY include post-interaction responses such as
described in Section 5.1. [[ See issue #95 (https://github.com/ietf- described in Section 5.1. [[ See issue #95 (https://github.com/ietf-
wg-gnap/gnap-core-protocol/issues/95) ]] wg-gnap/gnap-core-protocol/issues/95) ]]
Modification requests MUST NOT alter previously-issued access tokens. Modification requests MUST NOT alter previously-issued access tokens.
Instead, any access tokens issued from a continuation are considered Instead, any access tokens issued from a continuation are considered
new, separate access tokens. The AS MAY revoke existing access new, separate access tokens. The AS MAY revoke existing access
tokens after a modification has occurred. [[ See issue #96 tokens after a modification has occurred. [[ See issue #96
(https://github.com/ietf-wg-gnap/gnap-core-protocol/issues/96) ]] (https://github.com/ietf-wg-gnap/gnap-core-protocol/issues/96) ]]
If the modified request can be granted immediately by the AS, the If the modified request can be granted immediately by the AS, the
Section 3 MAY contain any newly-created access tokens (Section 3.2) grant response (Section 3) MAY contain any newly-created access
or newly-released subject claims (Section 3.4). The response MAY tokens (Section 3.2) or newly-released subject claims (Section 3.4).
contain a new "continue" response (Section 3.1) as described above. The response MAY contain a new "continue" response (Section 3.1) as
If interaction can occur, the response SHOULD contain interaction described above. If interaction can occur, the response SHOULD
responses (Section 3.3) as well. contain interaction responses (Section 3.3) as well.
For example, a client instance initially requests a set of resources For example, a client instance initially requests a set of resources
using references: using references:
POST /tx HTTP/1.1 POST /tx HTTP/1.1
Host: server.example.com Host: server.example.com
Content-Type: application/json Content-Type: application/json
Signature-Input: sig1=... Signature-Input: sig1=...
Signature: sig1=... Signature: sig1=...
Digest: sha256=... Digest: sha256=...
skipping to change at page 74, line 39 skipping to change at page 76, line 30
"finish": { "finish": {
"method": "redirect", "method": "redirect",
"uri": "https://client.example.net/return/123455", "uri": "https://client.example.net/return/123455",
"nonce": "LKLTI25DK82FX4T4QFZC" "nonce": "LKLTI25DK82FX4T4QFZC"
} }
}, },
"client": "987YHGRT56789IOLK" "client": "987YHGRT56789IOLK"
} }
Access is granted by the RO, and a token is issued by the AS. In its Access is granted by the RO, and a token is issued by the AS. In its
final response, the AS includes a "continue" field, which includes a final response, the AS includes a continue field, which includes a
separate access token for accessing the continuation API: separate access token for accessing the continuation API:
{ {
"continue": { "continue": {
"access_token": { "access_token": {
"value": "80UPRY5NM33OMUKMKSKU" "value": "80UPRY5NM33OMUKMKSKU"
}, },
"uri": "https://server.example.com/continue", "uri": "https://server.example.com/continue",
"wait": 30 "wait": 30
}, },
"access_token": { "access_token": {
"value": "RP1LT0-OS9M2P_R64TB", "value": "RP1LT0-OS9M2P_R64TB",
"access": [ "access": [
"read", "write" "read", "write"
] ]
} }
} }
This continue field allows the client instance to make an eventual
This "continue" field allows the client instance to make an eventual
continuation call. In the future, the client instance realizes that continuation call. In the future, the client instance realizes that
it no longer needs "write" access and therefore modifies its ongoing it no longer needs "write" access and therefore modifies its ongoing
request, here asking for just "read" access instead of both "read" request, here asking for just "read" access instead of both "read"
and "write" as before. and "write" as before.
PATCH /continue HTTP/1.1 PATCH /continue HTTP/1.1
Host: server.example.com Host: server.example.com
Content-Type: application/json Content-Type: application/json
Authorization: GNAP 80UPRY5NM33OMUKMKSKU Authorization: GNAP 80UPRY5NM33OMUKMKSKU
Signature-Input: sig1=... Signature-Input: sig1=...
skipping to change at page 75, line 44 skipping to change at page 77, line 27
{ {
"access_token": { "access_token": {
"access": [ "access": [
"read" "read"
] ]
} }
... ...
} }
The AS replaces the previous "access" from the first request, The AS replaces the previous access from the first request, allowing
allowing the AS to determine if any previously-granted consent the AS to determine if any previously-granted consent already
already applies. In this case, the AS would likely determine that applies. In this case, the AS would likely determine that reducing
reducing the breadth of the requested access means that new access the breadth of the requested access means that new access tokens can
tokens can be issued to the client instance. The AS would likely be issued to the client instance. The AS would likely revoke
revoke previously-issued access tokens that had the greater access previously-issued access tokens that had the greater access rights
rights associated with them, unless they had been issued with the associated with them, unless they had been issued with the durable
"durable" flag. flag.
{ {
"continue": { "continue": {
"access_token": { "access_token": {
"value": "M33OMUK80UPRY5NMKSKU" "value": "M33OMUK80UPRY5NMKSKU"
}, },
"uri": "https://server.example.com/continue", "uri": "https://server.example.com/continue",
"wait": 30 "wait": 30
}, },
"access_token": { "access_token": {
skipping to change at page 76, line 50 skipping to change at page 78, line 33
"finish": { "finish": {
"method": "redirect", "method": "redirect",
"uri": "https://client.example.net/return/123455", "uri": "https://client.example.net/return/123455",
"nonce": "LKLTI25DK82FX4T4QFZC" "nonce": "LKLTI25DK82FX4T4QFZC"
} }
}, },
"client": "987YHGRT56789IOLK" "client": "987YHGRT56789IOLK"
} }
Access is granted by the RO, and a token is issued by the AS. In its Access is granted by the RO, and a token is issued by the AS. In its
final response, the AS includes a "continue" field: final response, the AS includes a continue field:
{ {
"continue": { "continue": {
"access_token": { "access_token": {
"value": "80UPRY5NM33OMUKMKSKU" "value": "80UPRY5NM33OMUKMKSKU"
}, },
"uri": "https://server.example.com/continue", "uri": "https://server.example.com/continue",
"wait": 30 "wait": 30
}, },
"access_token": { "access_token": {
skipping to change at page 80, line 17 skipping to change at page 81, line 28
client instance is attempting to refresh the expired token. To client instance is attempting to refresh the expired token. To
support this, the AS MAY apply different lifetimes for the use of the support this, the AS MAY apply different lifetimes for the use of the
token in management vs. its use at an RS. An AS MUST NOT honor a token in management vs. its use at an RS. An AS MUST NOT honor a
rotation request for an access token that has been revoked, either by rotation request for an access token that has been revoked, either by
the AS or by the client instance through the token management URI the AS or by the client instance through the token management URI
(Section 6.2). (Section 6.2).
If the token is validated and the key is appropriate for the request, If the token is validated and the key is appropriate for the request,
the AS MUST invalidate the current access token associated with this the AS MUST invalidate the current access token associated with this
URL, if possible, and return a new access token response as described URL, if possible, and return a new access token response as described
in Section 3.2.1, unless the "multi_token" flag is specified in the in Section 3.2.1, unless the multi_token flag is specified in the
request. The value of the access token MUST NOT be the same as the request. The value of the access token MUST NOT be the same as the
current value of the access token used to access the management API. current value of the access token used to access the management API.
The response MAY include an updated access token management URL as The response MAY include an updated access token management URL as
well, and if so, the client instance MUST use this new URL to manage well, and if so, the client instance MUST use this new URL to manage
the new access token. [[ See issue #101 (https://github.com/ietf-wg- the new access token. [[ See issue #101 (https://github.com/ietf-wg-
gnap/gnap-core-protocol/issues/101) ]] gnap/gnap-core-protocol/issues/101) ]]
[[ See issue #102 (https://github.com/ietf-wg-gnap/gnap-core- [[ See issue #102 (https://github.com/ietf-wg-gnap/gnap-core-
protocol/issues/102) ]] protocol/issues/102) ]]
NOTE: '\' line wrapping per RFC 8792 NOTE: '\' line wrapping per RFC 8792
skipping to change at page 82, line 28 skipping to change at page 83, line 28
the token management function is specifically for the client the token management function is specifically for the client
instance's use. If the access token has already expired or has been instance's use. If the access token has already expired or has been
revoked through other means, the AS SHOULD honor the revocation revoked through other means, the AS SHOULD honor the revocation
request to the token management URL as valid, since the end result is request to the token management URL as valid, since the end result is
still the token not being usable. still the token not being usable.
7. Securing Requests from the Client Instance 7. Securing Requests from the Client Instance
In GNAP, the client instance secures its requests to the AS and RS by In GNAP, the client instance secures its requests to the AS and RS by
presenting an access token, presenting proof of a key that it presenting an access token, presenting proof of a key that it
possesses, or both an access token and key proof together. possesses (aka, a "key proof"), or both an access token and key proof
together.
* When an access token is used with a key proof, this is a bound * When an access token is used with a key proof, this is a bound
token request. This type of request is used for calls to the RS token request. This type of request is used for calls to the RS
as well as the AS during negotiation. as well as the AS during negotiation.
* When a key proof is used with no access token, this is a non- * When a key proof is used with no access token, this is a non-
authorized signed request. This type of request is used for calls authorized signed request. This type of request is used for calls
to the AS to initiate a negotiation. to the AS to initiate a negotiation.
* When an access token is used with no key proof, this is a bearer * When an access token is used with no key proof, this is a bearer
skipping to change at page 83, line 26 skipping to change at page 84, line 26
A key presented by value MUST be a public key in at least one A key presented by value MUST be a public key in at least one
supported format. If a key is sent in multiple formats, all the key supported format. If a key is sent in multiple formats, all the key
format values MUST be equivalent. Note that while most formats format values MUST be equivalent. Note that while most formats
present the full value of the public key, some formats present a present the full value of the public key, some formats present a
value cryptographically derived from the public key. value cryptographically derived from the public key.
proof (string) The form of proof that the client instance will use proof (string) The form of proof that the client instance will use
when presenting the key. The valid values of this field and the when presenting the key. The valid values of this field and the
processing requirements for each are detailed in Section 7.3. The processing requirements for each are detailed in Section 7.3. The
"proof" field is REQUIRED. proof field is REQUIRED.
jwk (object) The public key and its properties represented as a JSON jwk (object) The public key and its properties represented as a JSON
Web Key [RFC7517]. A JWK MUST contain the "alg" (Algorithm) and Web Key [RFC7517]. A JWK MUST contain the alg (Algorithm) and kid
"kid" (Key ID) parameters. The "alg" parameter MUST NOT be (Key ID) parameters. The alg parameter MUST NOT be "none". The
"none". The "x5c" (X.509 Certificate Chain) parameter MAY be used x5c (X.509 Certificate Chain) parameter MAY be used to provide the
to provide the X.509 representation of the provided public key. X.509 representation of the provided public key.
cert (string) PEM serialized value of the certificate used to sign cert (string) PEM serialized value of the certificate used to sign
the request, with optional internal whitespace per [RFC7468]. The the request, with optional internal whitespace per [RFC7468]. The
PEM header and footer are optionally removed. PEM header and footer are optionally removed.
cert#S256 (string) The certificate thumbprint calculated as per cert#S256 (string) The certificate thumbprint calculated as per
OAuth-MTLS [RFC8705] in base64 URL encoding. Note that this OAuth-MTLS [RFC8705] in base64 URL encoding. Note that this
format does not include the full public key. format does not include the full public key.
Additional key formats are defined in a registry TBD (Section 11). Additional key formats are defined in a registry TBD (Section 11).
This non-normative example shows a single key presented in multiple This non-normative example shows a single key presented in multiple
formats. This example key is intended to be used with the HTTP formats. This example key is intended to be used with the HTTP
Message Signatures ({{httpsig-binding}}) proofing mechanism, as Message Signatures ({{httpsig-binding}}) proofing mechanism, as
indicated by the "httpsig" value of the "proof" field. indicated by the httpsig value of the proof field.
"key": { "key": {
"proof": "httpsig", "proof": "httpsig",
"jwk": { "jwk": {
"kty": "RSA", "kty": "RSA",
"e": "AQAB", "e": "AQAB",
"kid": "xyz-1", "kid": "xyz-1",
"alg": "RS256", "alg": "RS256",
"n": "kOB5rR4Jv0GMeLaY6_It_r3ORwdf8ci_JtffXyaSx8xY..." "n": "kOB5rR4Jv0GMeLaY6_It_r3ORwdf8ci_JtffXyaSx8xY..."
}, },
skipping to change at page 84, line 39 skipping to change at page 85, line 39
Keys referenced in this manner MUST be bound to a single proofing Keys referenced in this manner MUST be bound to a single proofing
mechanism. mechanism.
The means of dereferencing this value are out of scope for this The means of dereferencing this value are out of scope for this
specification. specification.
7.2. Presenting Access Tokens 7.2. Presenting Access Tokens
The method the client instance uses to send an access token depends The method the client instance uses to send an access token depends
on whether the token is bound to a key, and if so which proofing on whether the token is bound to a key, and if so which proofing
method is associated with the key. This information is conveyed in method is associated with the key. This information is conveyed by
the "bound" and "key" parameters in the single (Section 3.2.1) and the key parameter and the bearer flag in the single (Section 3.2.1)
multiple access tokens (Section 3.2.2) responses. and multiple access tokens (Section 3.2.2) responses.
If the "flags" field does not contain the "bearer" flag and the "key" If the flags field does not contain the bearer flag and the key is
is absent, the access token MUST be sent using the same key and absent, the access token MUST be sent using the same key and proofing
proofing mechanism that the client instance used in its initial mechanism that the client instance used in its initial request (or
request (or its most recent rotation). its most recent rotation).
If the "flags" field does not contain the "bearer" flag and the "key" If the flags field does not contain the bearer flag and the key value
value is an object as described in Section 7.1, the access token MUST is an object as described in Section 7.1, the access token MUST be
be sent using the key and proofing mechanism defined by the value of sent using the key and proofing mechanism defined by the value of the
the "proof" field within the key object. proof field within the key object.
The access token MUST be sent using the HTTP "Authorization" request The access token MUST be sent using the HTTP "Authorization" request
header field and the "GNAP" authorization scheme along with a key header field and the "GNAP" authorization scheme along with a key
proof as described in Section 7.3 for the key bound to the access proof as described in Section 7.3 for the key bound to the access
token. For example, an "httpsig"-bound access token is sent as token. For example, an "httpsig"-bound access token is sent as
follows: follows:
Authorization: GNAP OS9M2PMHKUR64TB8N6BW7OZB8CDFONP219RP1LT0 NOTE: '\' line wrapping per RFC 8792
Signature-Input: sig1=(authorization);...
Signature: sig1=...
If the "flags" field contains the "bearer" flag, the access token is GET /stuff HTTP/1.1
a bearer token that MUST be sent using the "Authorization Request Host: resource.example.com
Header Field" method defined in [RFC6750]. Authorization: GNAP 80UPRY5NM33OMUKMKSKU
Signature-Input: sig1=("@method" "@target-uri" "authorization")\
;created=1618884475;keyid="gnap-rsa"
Signature: sig1=:KymTn1/++nwWsNHdc48sguMjnVSnvqQNrijQT0/kXDfljaIgHl\
o12NkEt4e5qZeCFutzRxWpHKtjVEDldIUSsktxj4Li7PgUNJtIkJkdA1EoebGz1X/\
AD3coqYpoaFsOcPyfXjYHYWFd8HxLOUz3imA8xbxS+J9GZAjyDjTfG6yfsMsfd10f\
nrDRJqalPNDEgOOwwyEtjht4MnzpV1Wf43YWwgEJOC2rvxPIeuNxWbUc5v/o3s3Zr\
ywo2sunUcwXwlmbgyiGY0vgGFWjdHfgKvjda7eNLTr7r3jPgo/GlOB3jyadD4xcKs\
S/idS3RGk1+e9jbGHK5cRTp0ZzF94kWw==:
If the flags field contains the bearer flag, the access token is a
bearer token that MUST be sent using the Authorization Request Header
Field method defined in [RFC6750].
Authorization: Bearer OS9M2PMHKUR64TB8N6BW7OZB8CDFONP219RP1LT0 Authorization: Bearer OS9M2PMHKUR64TB8N6BW7OZB8CDFONP219RP1LT0
The "Form-Encoded Body Parameter" and "URI Query Parameter" methods The Form-Encoded Body Parameter and URI Query Parameter methods of
of [RFC6750] MUST NOT be used. [RFC6750] MUST NOT be used.
[[ See issue #104 (https://github.com/ietf-wg-gnap/gnap-core- [[ See issue #104 (https://github.com/ietf-wg-gnap/gnap-core-
protocol/issues/104) ]] protocol/issues/104) ]]
The client software MUST reject as an error a situation where the The client software MUST reject as an error a situation where the
"flags" field contains the "bearer" flag and the "key" field is flags field contains the bearer flag and the key field is present
present with any value. with any value.
7.3. Proving Possession of a Key with a Request 7.3. Proving Possession of a Key with a Request
Any keys presented by the client instance to the AS or RS MUST be Any keys presented by the client instance to the AS or RS MUST be
validated as part of the request in which they are presented. The validated as part of the request in which they are presented. The
type of binding used is indicated by the proof parameter of the key type of binding used is indicated by the proof parameter of the key
object in Section 7.1. Values defined by this specification are as object in Section 7.1. Values defined by this specification are as
follows: follows:
httpsig HTTP Signing signature header httpsig HTTP Signing signature header
skipping to change at page 86, line 19 skipping to change at page 87, line 29
nature of the request. Key binding method definitions SHOULD nature of the request. Key binding method definitions SHOULD
enumerate how these requirements are fulfilled. enumerate how these requirements are fulfilled.
When a key proofing mechanism is bound to an access token, the key When a key proofing mechanism is bound to an access token, the key
being presented MUST be the key associated with the access token and being presented MUST be the key associated with the access token and
the access token MUST be covered by the signature method of the the access token MUST be covered by the signature method of the
proofing mechanism. proofing mechanism.
The key binding methods in this section MAY be used by other The key binding methods in this section MAY be used by other
components making calls as part of GNAP, such as the extensions components making calls as part of GNAP, such as the extensions
allowing the RS to make calls to the AS defined in {{I-D.ietf-gnap- allowing the RS to make calls to the AS defined in
resource-servers}}. To facilitate this extended use, the sections [I-D.ietf-gnap-resource-servers]. To facilitate this extended use,
below are defined in generic terms of the "sender" and "verifier" of the sections below are defined in generic terms of the "signer" and
the HTTP message. In the core functions of GNAP, the "sender" is the "verifier" of the HTTP message. In the core functions of GNAP, the
client instance and the "verifier" is the AS or RS, as appropriate. "signer" is the client instance and the "verifier" is the AS or RS,
as appropriate.
When used for delegation in GNAP, these key binding mechanisms allow When used for delegation in GNAP, these key binding mechanisms allow
the AS to ensure that the keys presented by the client instance in the AS to ensure that the keys presented by the client instance in
the initial request are in control of the party calling any follow-up the initial request are in control of the party calling any follow-up
or continuation requests. To facilitate this requirement, the or continuation requests. To facilitate this requirement, the
continuation response (Section 3.1) includes an access token bound to continuation response (Section 3.1) includes an access token bound to
the client instance's key (Section 2.3), and that key (or its most the client instance's key (Section 2.3), and that key (or its most
recent rotation) MUST be proved in all continuation requests recent rotation) MUST be proved in all continuation requests
Section 5. Token management requests Section 6 are similarly bound Section 5. Token management requests Section 6 are similarly bound
to either the access token's own key or, in the case of bearer to either the access token's own key or, in the case of bearer
tokens, the client instance's key. tokens, the client instance's key.
[[ See issue #105 (https://github.com/ietf-wg-gnap/gnap-core- [[ See issue #105 (https://github.com/ietf-wg-gnap/gnap-core-
protocol/issues/105) ]] protocol/issues/105) ]]
In the following sections, unless otherwise noted, the RS256 JOSE
In the following sections, unless otherwise noted, the "RS256" JOSE
Signature Algorithm is applied using the following RSA key (presented Signature Algorithm is applied using the following RSA key (presented
here in JWK format): here in JWK format):
NOTE: '\' line wrapping per RFC 8792 NOTE: '\' line wrapping per RFC 8792
{ {
"kid": "gnap-rsa", "kid": "gnap-rsa",
"p": "xS4-YbQ0SgrsmcA7xDzZKuVNxJe3pCYwdAe6efSy4hdDgF9-vhC5gjaRk\ "p": "xS4-YbQ0SgrsmcA7xDzZKuVNxJe3pCYwdAe6efSy4hdDgF9-vhC5gjaRk\
i1wWuERSMW4Tv44l5HNrL-Bbj_nCJxr_HAOaesDiPn2PnywwEfg3Nv95Nn-\ i1wWuERSMW4Tv44l5HNrL-Bbj_nCJxr_HAOaesDiPn2PnywwEfg3Nv95Nn-\
eilhqXRaW-tJKEMjDHu_fmJBeemHNZI412gBnXdGzDVo22dvYoxd6GM", eilhqXRaW-tJKEMjDHu_fmJBeemHNZI412gBnXdGzDVo22dvYoxd6GM",
skipping to change at page 87, line 43 skipping to change at page 88, line 46
"n": "hYOJ-XOKISdMMShn_G4W9m20mT0VWtQBsmBBkI2cmRt4Ai8BfYdHsFzAt\ "n": "hYOJ-XOKISdMMShn_G4W9m20mT0VWtQBsmBBkI2cmRt4Ai8BfYdHsFzAt\
YKOjpBR1RpKpJmVKxIGNy0g6Z3ad2XYsh8KowlyVy8IkZ8NMwSrcUIBZGYX\ YKOjpBR1RpKpJmVKxIGNy0g6Z3ad2XYsh8KowlyVy8IkZ8NMwSrcUIBZGYX\
jHpwjzvfGvXH_5KJlnR3_uRUp4Z4Ujk2bCaKegDn11V2vxE41hqaPUnhRZx\ jHpwjzvfGvXH_5KJlnR3_uRUp4Z4Ujk2bCaKegDn11V2vxE41hqaPUnhRZx\
e0jRETddzsE3mu1SK8dTCROjwUl14mUNo8iTrTm4n0qDadz8BkPo-uv4BC0\ e0jRETddzsE3mu1SK8dTCROjwUl14mUNo8iTrTm4n0qDadz8BkPo-uv4BC0\
bunS0K3bA_3UgVp7zBlQFoFnLTO2uWp_muLEWGl67gBq9MO3brKXfGhi3kO\ bunS0K3bA_3UgVp7zBlQFoFnLTO2uWp_muLEWGl67gBq9MO3brKXfGhi3kO\
zywzwPTuq-cVQDyEN7aL0SxCb3Hc4IdqDaMg8qHUyObpPitDQ" zywzwPTuq-cVQDyEN7aL0SxCb3Hc4IdqDaMg8qHUyObpPitDQ"
} }
7.3.1. HTTP Message Signing 7.3.1. HTTP Message Signing
This method is indicated by "httpsig" in the "proof" field. The This method is indicated by httpsig in the proof field. The signer
sender creates an HTTP Message Signature as described in creates an HTTP Message Signature as described in
[I-D.ietf-httpbis-message-signatures]. [I-D.ietf-httpbis-message-signatures].
The covered content of the signature MUST include the following: The message components of the signature MUST include the following:
@request-target: the target of the HTTP request @method: the method used in the HTTP request
digest: The Digest header as defined in [RFC3230]. When the request @target-uri: the full request URL of the HTTP request
content-digest or digest: The Content-Digest or Digest header as
defined in [I-D.ietf-httpbis-digest-headers]. When the request
message has a body, the signer MUST calculate this header value message has a body, the signer MUST calculate this header value
and the verifier MUST validate this header. and the verifier MUST validate this field value. Use of Content-
Digest is RECOMMENDED. Use of content-encoding agnostic digest
methods (such as id-sha-256) is RECOMMENDED.
When the request is bound to an access token, the covered content When the request is bound to an access token, the covered content
MUST also include: MUST also include:
authorization: The Authorization header used to present the access authorization: The Authorization header used to present the access
token as discussed in Section 7.2. token as discussed in Section 7.2.
Other covered content MAY also be included. Other message components MAY also be included.
If the signer's key presented is a JWK, the "keyid" parameter of the If the signer's key presented is a JWK, the keyid parameter of the
signature MUST be set to the "kid" value of the JWK, the signing signature MUST be set to the kid value of the JWK, the signing
algorithm used MUST be the JWS algorithm denoted by the key's "alg" algorithm used MUST be the JWS algorithm denoted by the key's alg
field, and the explicit "alg" signature parameter MUST NOT be field, and the explicit alg signature parameter MUST NOT be included.
included.
In this example, the message body is the following JSON object: In this example, the message body is the following JSON object:
NOTE: '\' line wrapping per RFC 8792 NOTE: '\' line wrapping per RFC 8792
{ {
"access_token": { "access_token": {
"access": [ "access": [
"dolphin-metadata" "dolphin-metadata"
] ]
skipping to change at page 89, line 44 skipping to change at page 90, line 44
N7aL0SxCb3Hc4IdqDaMg8qHUyObpPitDQ" N7aL0SxCb3Hc4IdqDaMg8qHUyObpPitDQ"
} }
} }
"display": { "display": {
"name": "My Client Display Name", "name": "My Client Display Name",
"uri": "https://client.foo/" "uri": "https://client.foo/"
}, },
} }
} }
This body is hashed for the Digest header using SHA-256 into the This body is hashed for the Content-Digest header using id-sha-256
following encoded value: into the following encoded value:
SHA-256=98QzyNVYpdgTrWBKpC4qFSCmmR+CrwwvUoiaDCSjKxw= id-sha-256=98QzyNVYpdgTrWBKpC4qFSCmmR+CrwwvUoiaDCSjKxw=
The HTTP message signature input string is calculated to be the The HTTP message signature input string is calculated to be the
following: following:
NOTE: '\' line wrapping per RFC 8792 NOTE: '\' line wrapping per RFC 8792
"@request-target": post /gnap "@method": POST
"host": server.example.com "@target-uri": https://server.example.com/gnap
"content-type": application/json "content-type": application/json
"digest": SHA-256=98QzyNVYpdgTrWBKpC4qFSCmmR+CrwwvUoiaDCSjKxw= "content-digest": id-sha-256=98QzyNVYpdgTrWBKpC4qFSCmmR+Crwwv\
UoiaDCSjKxw=
"content-length": 986 "content-length": 986
"@signature-params": ("@request-target" "host" "content-type" \ "@signature-params": ("@method" "@target-uri" "content-type" \
"digest" "content-length");created=1618884475;keyid="gnap-rsa" "content-digest" "content-length");created=1618884475\
;keyid="gnap-rsa"
This leads to the following full HTTP message request: This leads to the following full HTTP message request:
NOTE: '\' line wrapping per RFC 8792 NOTE: '\' line wrapping per RFC 8792
POST /gnap HTTP/1.1 POST /gnap HTTP/1.1
Host: server.example.com Host: server.example.com
Content-Type: application/json Content-Type: application/json
Content-Length: 986 Content-Length: 986
Digest: SHA-256=98QzyNVYpdgTrWBKpC4qFSCmmR+CrwwvUoiaDCSjKxw= Content-Digest: id-sha-256=98QzyNVYpdgTrWBKpC4qFSCmmR+CrwwvUoiaDCSj\
Signature-Input: sig1=("@request-target" "host" "content-type" \ Kxw=
"digest" "content-length");created=1618884475;keyid="gnap-rsa" Signature-Input: sig1=("@method" "@target-uri" "content-type" \
Signature: \ "content-digest" "content-length");created=1618884475\
sig1=:axj8FLOvEWBcwh+Xk6VTTKXxqo4XNygleTDJ8h3ZJfi1sSmWrRtyo9RG/dc\ ;keyid="gnap-rsa"
miZmdszRjWbg+/ixVZpA4BL3AOwEOxxtmHAXNB8uJ0I3tfbs6Suyk4sEo8zPr+MJq\ Signature: sig1=:SatKrAh2qNxbDBY6H3XUtpWn07aSrukpi3202L4DIPLLGgKdSu\
MjxdJEUgAQAy2AH+wg5a7CKq4IdLTulFK9njUIeG7MygHumeiumM3DbDQAHgF46dV\ XyObjdCK/agmEx36xyn40iiCAqYskXugpNARianBiWKOkcWHhSs31FSTSoJ8vvGpJ\
q5UC6KJnqhGM1rFC128jd2D0sgWKCUgKGCHtfR159zfKWcEO9krsLoOnCdTzm1UyD\ 4GxemDPvI6BXmLZtJvYBehoXtfcRFKGLzYOtbbtefzw2vP+k19W4PrhNmxFEUCepT\
DMjkIjqeN/1j8PdMJaRAwV4On079O0DVu6bl1jVtkzo/e/ZmwPr/X436V4xiw/hZt\ KRk0sBoz4zIYK6FqEAHir0oRjwdCcXHFqI9U6+/DgpuxjFFX+OSZehmN6Q1quJgu0\
w4sfNsSbmsT0+UAQ20X/xaw==: FITmsC9OANs5hwIAkXGJNdv3FuxAZAVrSnUScuGutSJXAn1daXToewVgBA+IrQ86m\
lsXtWgvmTTXENUvOELV6qTV2nenwr/UQ==:
{ {
"access_token": { "access_token": {
"access": [ "access": [
"dolphin-metadata" "dolphin-metadata"
] ]
}, },
"interact": { "interact": {
"start": ["redirect"], "start": ["redirect"],
"finish": { "finish": {
skipping to change at page 91, line 24 skipping to change at page 92, line 27
} }
} }
"display": { "display": {
"name": "My Client Display Name", "name": "My Client Display Name",
"uri": "https://client.foo/" "uri": "https://client.foo/"
}, },
} }
} }
If the HTTP Message includes a message body, the verifier MUST If the HTTP Message includes a message body, the verifier MUST
calculate and verify the value of the "Digest" header. The verifier calculate and verify the value of the Digest or Content-Digest
MUST ensure that the signature includes all required covered content. header. The verifier MUST ensure that the signature covers all
The verifier MUST validate the signature against the expected key of required message components. The verifier MUST validate the
the signer. signature against the expected key of the signer.
7.3.2. Mutual TLS 7.3.2. Mutual TLS
This method is indicated by "mtls" in the "proof" field. The signer This method is indicated by mtls in the proof field. The signer
presents its TLS client certificate during TLS negotiation with the presents its TLS client certificate during TLS negotiation with the
verifier. verifier.
In this example, the certificate is communicated to the application In this example, the certificate is communicated to the application
through the "Client-Cert" header from a TLS reverse proxy, leading to through the Client-Cert header from a TLS reverse proxy, leading to
the following full HTTP request message: the following full HTTP request message:
POST /gnap HTTP/1.1 POST /gnap HTTP/1.1
Host: server.example.com Host: server.example.com
Content-Type: application/jose Content-Type: application/jose
Content-Length: 1567 Content-Length: 1567
Client-Cert: \ Client-Cert: \
:MIIC6jCCAdKgAwIBAgIGAXjw74xPMA0GCSqGSIb3DQEBCwUAMDYxNDAyBgNVBAMM\ :MIIC6jCCAdKgAwIBAgIGAXjw74xPMA0GCSqGSIb3DQEBCwUAMDYxNDAyBgNVBAMM\
K05JWU15QmpzRGp5QkM5UDUzN0Q2SVR6a3BEOE50UmppOXlhcEV6QzY2bVEwHhcN\ K05JWU15QmpzRGp5QkM5UDUzN0Q2SVR6a3BEOE50UmppOXlhcEV6QzY2bVEwHhcN\
MjEwNDIwMjAxODU0WhcNMjIwMjE0MjAxODU0WjA2MTQwMgYDVQQDDCtOSVlNeUJq\ MjEwNDIwMjAxODU0WhcNMjIwMjE0MjAxODU0WjA2MTQwMgYDVQQDDCtOSVlNeUJq\
skipping to change at page 93, line 20 skipping to change at page 94, line 22
The verifier compares the TLS client certificate presented during The verifier compares the TLS client certificate presented during
mutual TLS negotiation to the expected key of the signer. Since the mutual TLS negotiation to the expected key of the signer. Since the
TLS connection covers the entire message, there are no additional TLS connection covers the entire message, there are no additional
requirements to check. requirements to check.
Note that in many instances, the verifier will not do a full Note that in many instances, the verifier will not do a full
certificate chain validation of the presented TLS client certificate, certificate chain validation of the presented TLS client certificate,
as the means of trust for this certificate could be in something as the means of trust for this certificate could be in something
other than a PKI system, such as a static registration or trust-on- other than a PKI system, such as a static registration or trust-on-
first-use. first-use. See Section 12.16 and Section 12.17 for some additional
considerations for this key proofing method.
[[ See issue #110 (https://github.com/ietf-wg-gnap/gnap-core-
protocol/issues/110) ]]
7.3.3. Detached JWS 7.3.3. Detached JWS
This method is indicated by "jwsd" in the "proof" field. A JWS This method is indicated by jwsd in the proof field. A JWS [RFC7515]
[RFC7515] object is created as follows: object is created as follows:
To protect the request, the JOSE header of the signature contains the To protect the request, the JOSE header of the signature contains the
following parameters: following parameters:
kid (string) The key identifier. RECOMMENDED. If the key is kid (string) The key identifier. RECOMMENDED. If the key is
presented in JWK format, this MUST be the value of the "kid" field presented in JWK format, this MUST be the value of the kid field
of the key. of the key.
alg (string) The algorithm used to sign the request. REQUIRED. alg (string) The algorithm used to sign the request. REQUIRED.
MUST be appropriate to the key presented. If the key is presented MUST be appropriate to the key presented. If the key is presented
as a JWK, this MUST be equal to the "alg" parameter of the key. as a JWK, this MUST be equal to the alg parameter of the key.
MUST NOT be "none". MUST NOT be none.
typ (string) The type header, value "gnap-binding+jwsd". REQUIRED typ (string) The type header, value "gnap-binding+jwsd". REQUIRED
htm (string) The HTTP Method used to make this request, as an htm (string) The HTTP Method used to make this request, as an
uppercase ASCII string. REQUIRED uppercase ASCII string. REQUIRED
uri (string) The HTTP URI used for this request, including all path uri (string) The HTTP URI used for this request, including all path
and query components and no fragment component. REQUIRED and query components and no fragment component. REQUIRED
created (integer) A timestamp of when the signature was created, in created (integer) A timestamp of when the signature was created, in
skipping to change at page 94, line 18 skipping to change at page 95, line 18
encoding of the associated access token's value. REQUIRED if the encoding of the associated access token's value. REQUIRED if the
request protects an access token. request protects an access token.
If the HTTP request has a message body, such as an HTTP POST or PUT If the HTTP request has a message body, such as an HTTP POST or PUT
method, the payload of the JWS object is the Base64url encoding method, the payload of the JWS object is the Base64url encoding
(without padding) of the SHA256 digest of the bytes of the body. If (without padding) of the SHA256 digest of the bytes of the body. If
the request being made does not have a message body, such as an HTTP the request being made does not have a message body, such as an HTTP
GET, OPTIONS, or DELETE method, the JWS signature is calculated over GET, OPTIONS, or DELETE method, the JWS signature is calculated over
an empty payload. an empty payload.
The client instance presents the signed object in compact form The signer presents the signed object in compact form [RFC7515] in
[RFC7515] in the Detached-JWS HTTP Header field. the Detached-JWS HTTP Header field.
In this example, the JOSE Header contains the following parameters: In this example, the JOSE Header contains the following parameters:
{ {
"alg": "RS256", "alg": "RS256",
"kid": "gnap-rsa", "kid": "gnap-rsa",
"uri": "https://server.example.com/gnap", "uri": "https://server.example.com/gnap",
"htm": "POST", "htm": "POST",
"typ": "gnap-binding+jwsd", "typ": "gnap-binding+jwsd",
"created": 1618884475 "created": 1618884475
skipping to change at page 97, line 19 skipping to change at page 98, line 19
When the verifier receives the Detached-JWS header, it MUST parse and When the verifier receives the Detached-JWS header, it MUST parse and
validate the JWS object. The signature MUST be validated against the validate the JWS object. The signature MUST be validated against the
expected key of the signer. All required fields MUST be present and expected key of the signer. All required fields MUST be present and
their values MUST be valid. If the HTTP message request contains a their values MUST be valid. If the HTTP message request contains a
body, the verifier MUST calculate the hash of body just as the signer body, the verifier MUST calculate the hash of body just as the signer
does, with no normalization or transformation of the request. does, with no normalization or transformation of the request.
7.3.4. Attached JWS 7.3.4. Attached JWS
This method is indicated by "jws" in the "proof" field. A JWS This method is indicated by jws in the proof field. A JWS [RFC7515]
[RFC7515] object is created as follows: object is created as follows:
The JOSE header MUST contain the "kid" parameter of the key bound to The JOSE header MUST contain the kid parameter of the key bound to
this client instance for this request. The "alg" parameter MUST be this signer for this request. The alg parameter MUST be set to a
set to a value appropriate for the key identified by kid and MUST NOT value appropriate for the key identified by kid and MUST NOT be none.
be "none".
To protect the request, the JWS header MUST contain the following To protect the request, the JWS header MUST contain the following
additional parameters. additional parameters.
typ (string) The type header, value "gnap-binding+jws". typ (string) The type header, value "gnap-binding+jws".
htm (string) The HTTP Method used to make this request, as an htm (string) The HTTP Method used to make this request, as an
uppercase ASCII string. uppercase ASCII string.
uri (string) The HTTP URI used for this request, including all path uri (string) The HTTP URI used for this request, including all path
skipping to change at page 98, line 8 skipping to change at page 98, line 48
integer seconds since UNIX Epoch integer seconds since UNIX Epoch
ath (string) When a request is bound to an access token, the access ath (string) When a request is bound to an access token, the access
token hash value. The value MUST be the result of Base64url token hash value. The value MUST be the result of Base64url
encoding (with no padding) the SHA-256 digest of the ASCII encoding (with no padding) the SHA-256 digest of the ASCII
encoding of the associated access token's value. encoding of the associated access token's value.
If the HTTP request has a message body, such as an HTTP POST or PUT If the HTTP request has a message body, such as an HTTP POST or PUT
method, the payload of the JWS object is the JSON serialized body of method, the payload of the JWS object is the JSON serialized body of
the request, and the object is signed according to JWS and serialized the request, and the object is signed according to JWS and serialized
into compact form [RFC7515]. The client instance presents the JWS as into compact form [RFC7515]. The signer presents the JWS as the body
the body of the request along with a content type of "application/ of the request along with a content type of application/jose. The
jose". The AS MUST extract the payload of the JWS and treat it as verifier MUST extract the payload of the JWS and treat it as the
the request body for further processing. request body for further processing.
If the request being made does not have a message body, such as an If the request being made does not have a message body, such as an
HTTP GET, OPTIONS, or DELETE method, the JWS signature is calculated HTTP GET, OPTIONS, or DELETE method, the JWS signature is calculated
over an empty payload and passed in the "Detached-JWS" header as over an empty payload and passed in the Detached-JWS header as
described in Section 7.3.3. described in Section 7.3.3.
In this example, the JOSE header contains the following parameters: In this example, the JOSE header contains the following parameters:
{ {
"alg": "RS256", "alg": "RS256",
"kid": "gnap-rsa", "kid": "gnap-rsa",
"uri": "https://server.example.com/gnap", "uri": "https://server.example.com/gnap",
"htm": "POST", "htm": "POST",
"typ": "gnap-binding+jwsd", "typ": "gnap-binding+jwsd",
skipping to change at page 101, line 19 skipping to change at page 102, line 19
used when the client instance requests an access token (Section 2.1) used when the client instance requests an access token (Section 2.1)
and when an access token is returned (Section 3.2). and when an access token is returned (Section 3.2).
The root of this structure is a JSON array. The elements of the JSON The root of this structure is a JSON array. The elements of the JSON
array represent rights of access that are associated with the the array represent rights of access that are associated with the the
access token. The resulting access is the union of all elements access token. The resulting access is the union of all elements
within the array. within the array.
The access associated with the access token is described using The access associated with the access token is described using
objects that each contain multiple dimensions of access. Each object objects that each contain multiple dimensions of access. Each object
contains a REQUIRED "type" property that determines the type of API contains a REQUIRED type property that determines the type of API
that the token is used for. that the token is used for.
type (string) The type of resource request as a string. This field type (string) The type of resource request as a string. This field
MAY define which other fields are allowed in the request object. MAY define which other fields are allowed in the request object.
This field is REQUIRED. This field is REQUIRED.
The value of the "type" field is under the control of the AS. This The value of the type field is under the control of the AS. This
field MUST be compared using an exact byte match of the string value field MUST be compared using an exact byte match of the string value
against known types by the AS. The AS MUST ensure that there is no against known types by the AS. The AS MUST ensure that there is no
collision between different authorization data types that it collision between different authorization data types that it
supports. The AS MUST NOT do any collation or normalization of data supports. The AS MUST NOT do any collation or normalization of data
types during comparison. It is RECOMMENDED that designers of types during comparison. It is RECOMMENDED that designers of
general-purpose APIs use a URI for this field to avoid collisions general-purpose APIs use a URI for this field to avoid collisions
between multiple API types protected by a single AS. between multiple API types protected by a single AS.
While it is expected that many APIs will have their own properties, a While it is expected that many APIs will have their own properties, a
set of common properties are defined here. Specific API set of common properties are defined here. Specific API
skipping to change at page 102, line 17 skipping to change at page 103, line 17
medical API or a bank account number for a financial API. medical API or a bank account number for a financial API.
privileges (array of strings) The types or levels of privilege being privileges (array of strings) The types or levels of privilege being
requested at the resource. For example, a client instance asking requested at the resource. For example, a client instance asking
for administrative level access, or access when the resource owner for administrative level access, or access when the resource owner
is no longer online. is no longer online.
The following non-normative example is describing three kinds of The following non-normative example is describing three kinds of
access (read, write, delete) to each of two different locations and access (read, write, delete) to each of two different locations and
two different data types (metadata, images) for a single access token two different data types (metadata, images) for a single access token
using the fictitious "photo-api" type definition. using the fictitious photo-api type definition.
"access": [ "access": [
{ {
"type": "photo-api", "type": "photo-api",
"actions": [ "actions": [
"read", "read",
"write", "write",
"delete" "delete"
], ],
"locations": [ "locations": [
skipping to change at page 102, line 40 skipping to change at page 103, line 40
], ],
"datatypes": [ "datatypes": [
"metadata", "metadata",
"images" "images"
] ]
} }
] ]
The access requested for a given object when using these fields is The access requested for a given object when using these fields is
the cross-product of all fields of the object. That is to say, the the cross-product of all fields of the object. That is to say, the
object represents a request for all "actions" listed to be used at object represents a request for all actions listed to be used at all
all "locations" listed for all possible "datatypes" listed within the locations listed for all possible datatypes listed within the object.
object. Assuming the request above was granted, the client instance Assuming the request above was granted, the client instance could
could assume that it would be able to do a "read" action against the assume that it would be able to do a read action against the images
"images" on the first server as well as a "delete" action on the on the first server as well as a delete action on the metadata of the
"metadata" of the second server, or any other combination of these second server, or any other combination of these fields, using the
fields, using the same access token. same access token.
To request a different combination of access, such as requesting one To request a different combination of access, such as requesting one
of the possible "actions" against one of the possible "locations" and of the possible actions against one of the possible locations and a
a different choice of possible "actions" against a different one of different choice of possible actions against a different one of the
the possible "locations", the client instance can include multiple possible locations, the client instance can include multiple separate
separate objects in the "resources" array. The following non- objects in the resources array. The following non-normative example
normative example uses the same fictitious "photo-api" type uses the same fictitious photo-api type definition to request a
definition to request a single access token with more specifically single access token with more specifically targeted access rights by
targeted access rights by using two discrete objects within the using two discrete objects within the request.
request.
"access": [ "access": [
{ {
"type": "photo-api", "type": "photo-api",
"actions": [ "actions": [
"read" "read"
], ],
"locations": [ "locations": [
"https://server.example.net/" "https://server.example.net/"
], ],
skipping to change at page 103, line 37 skipping to change at page 104, line 36
], ],
"locations": [ "locations": [
"https://resource.local/other" "https://resource.local/other"
], ],
"datatypes": [ "datatypes": [
"metadata" "metadata"
] ]
} }
] ]
The access requested here is for "read" access to "images" on one The access requested here is for read access to images on one server
server while simultaneously requesting "write" and "delete" access while simultaneously requesting write and delete access for metadata
for "metadata" on a different server, but importantly without on a different server, but importantly without requesting write or
requesting "write" or "delete" access to "images" on the first delete access to images on the first server.
server.
It is anticipated that API designers will use a combination of common It is anticipated that API designers will use a combination of common
fields defined in this specification as well as fields specific to fields defined in this specification as well as fields specific to
the API itself. The following non-normative example shows the use of the API itself. The following non-normative example shows the use of
both common and API-specific fields as part of two different both common and API-specific fields as part of two different
fictitious API "type" values. The first access request includes the fictitious API type values. The first access request includes the
"actions", "locations", and "datatypes" fields specified here as well actions, locations, and datatypes fields specified here as well as
as the API-specific "geolocation" field. The second access request the API-specific geolocation field. The second access request
includes the "actions" and "identifier" fields specified here as well includes the actions and identifier fields specified here as well as
as the API-specific "currency" field. the API-specific currency field.
"access": [ "access": [
{ {
"type": "photo-api", "type": "photo-api",
"actions": [ "actions": [
"read", "read",
"write" "write"
], ],
"locations": [ "locations": [
"https://server.example.net/", "https://server.example.net/",
skipping to change at page 105, line 13 skipping to change at page 106, line 13
] ]
This value is opaque to the client instance and MAY be any valid JSON This value is opaque to the client instance and MAY be any valid JSON
string, and therefore could include spaces, unicode characters, and string, and therefore could include spaces, unicode characters, and
properly escaped string sequences. However, in some situations the properly escaped string sequences. However, in some situations the
value is intended to be seen and understood by the client software's value is intended to be seen and understood by the client software's
developer. In such cases, the API designer choosing any such human- developer. In such cases, the API designer choosing any such human-
readable strings SHOULD take steps to ensure the string values are readable strings SHOULD take steps to ensure the string values are
not easily confused by a developer, such as by limiting the strings not easily confused by a developer, such as by limiting the strings
to easily disambiguated characters. to easily disambiguated characters.
This functionality is similar in practice to OAuth 2.0's "scope" This functionality is similar in practice to OAuth 2.0's scope
parameter [RFC6749], where a single string represents the set of parameter [RFC6749], where a single string represents the set of
access rights requested by the client instance. As such, the access rights requested by the client instance. As such, the
reference string could contain any valid OAuth 2.0 scope value as in reference string could contain any valid OAuth 2.0 scope value as in
Appendix D.5. Note that the reference string here is not bound to Appendix D.5. Note that the reference string here is not bound to
the same character restrictions as in OAuth 2.0's "scope" definition. the same character restrictions as in OAuth 2.0's scope definition.
A single "access" array MAY include both object-type and string-type A single access array MAY include both object-type and string-type
resource items. In this non-normative example, the client instance resource items. In this non-normative example, the client instance
is requesting access to a "photo-api" and "financial-transaction" API is requesting access to a photo-api and financial-transaction API
type as well as the reference values of "read", "dolphin-metadata", type as well as the reference values of read, dolphin-metadata, and
and "some other thing". some other thing.
"access": [ "access": [
{ {
"type": "photo-api", "type": "photo-api",
"actions": [ "actions": [
"read", "read",
"write", "write",
"delete" "delete"
], ],
"locations": [ "locations": [
skipping to change at page 107, line 22 skipping to change at page 108, line 22
list correspond to the possible values for the interaction start list correspond to the possible values for the interaction start
section (Section 2.5.1) of the request. section (Section 2.5.1) of the request.
interaction_finish_methods_supported (array of strings) OPTIONAL. A interaction_finish_methods_supported (array of strings) OPTIONAL. A
list of the AS's interaction finish methods. The values of this list of the AS's interaction finish methods. The values of this
list correspond to the possible values for the method element of list correspond to the possible values for the method element of
the interaction finish section (Section 2.5.2) of the request. the interaction finish section (Section 2.5.2) of the request.
key_proofs_supported (array of strings) OPTIONAL. A list of the key_proofs_supported (array of strings) OPTIONAL. A list of the
AS's supported key proofing mechanisms. The values of this list AS's supported key proofing mechanisms. The values of this list
correspond to possible values of the "proof" field of the key correspond to possible values of the proof field of the key
section (Section 7.1) of the request. section (Section 7.1) of the request.
subject_formats_supported (array of strings) OPTIONAL. A list of subject_formats_supported (array of strings) OPTIONAL. A list of
the AS's supported subject identifier types. The values of this the AS's supported subject identifier types. The values of this
list correspond to possible values of the subject identifier list correspond to possible values of the subject identifier
section (Section 2.2) of the request. section (Section 2.2) of the request.
assertions_supported (array of strings) OPTIONAL. A list of the assertions_supported (array of strings) OPTIONAL. A list of the
AS's supported assertion formats. The values of this list AS's supported assertion formats. The values of this list
correspond to possible values of the subject assertion section correspond to possible values of the subject assertion section
(Section 2.2) of the request. (Section 2.2) of the request.
The information returned from this method is for optimization The information returned from this method is for optimization
purposes only. The AS MAY deny any request, or any portion of a purposes only. The AS MAY deny any request, or any portion of a
request, even if it lists a capability as supported. For example, a request, even if it lists a capability as supported. For example, a
given client instance can be registered with the "mtls" key proofing given client instance can be registered with the mtls key proofing
mechanism, but the AS also returns other proofing methods, then the mechanism, but the AS also returns other proofing methods, then the
AS will deny a request from that client instance using a different AS will deny a request from that client instance using a different
proofing mechanism. proofing mechanism.
9.1. RS-first Method of AS Discovery 9.1. RS-first Method of AS Discovery
If the client instance calls an RS without an access token, or with If the client instance calls an RS without an access token, or with
an invalid access token, the RS MAY respond to the client instance an invalid access token, the RS MAY respond to the client instance
with an authentication header indicating that GNAP needs to be used with an authentication header indicating that GNAP needs to be used
to access the resource. The address of the GNAP endpoint MUST be to access the resource. The address of the GNAP endpoint MUST be
sent in the "as_uri" parameter. The RS MAY additionally return a sent in the "as_uri" parameter. The RS MAY additionally return a
resource reference that the client instance MAY use in its access resource reference that the client instance MAY use in its access
token request. This resource reference MUST be sufficient for at token request. This resource reference MUST be sufficient for at
least the action the client instance was attempting to take at the RS least the action the client instance was attempting to take at the RS
and MAY be more powerful. The means for the RS to determine the and MAY be more powerful. The means for the RS to determine the
resource reference are out of scope of this specification, but some resource reference are out of scope of this specification, but some
dynamic methods are discussed in dynamic methods are discussed in [I-D.ietf-gnap-resource-servers].
[I-D.draft-ietf-gnap-resource-servers]. The content of the resource The content of the resource reference is opaque to the client
reference is opaque to the client instance. instance.
NOTE: '\' line wrapping per RFC 8792 NOTE: '\' line wrapping per RFC 8792
WWW-Authenticate: \ WWW-Authenticate: \
GNAP as_uri=https://server.example/tx,access=FWWIKYBQ6U56NL1 GNAP as_uri=https://server.example/tx,access=FWWIKYBQ6U56NL1
The client instance then makes a request to the "as_uri" as described The client instance then makes a request to the "as_uri" as described
in Section 2, with the value of "access" as one of the members of the in Section 2, with the value of "access" as one of the members of the
"access" array in the "access_token" portion of the request. The access array in the access_token portion of the request. The client
client instance MAY request additional resources and other instance MAY request additional resources and other information. The
information. The client instance MAY request multiple access tokens. client instance MAY request multiple access tokens.
In this non-normative example, the client instance is requesting a In this non-normative example, the client instance is requesting a
single access token using the resource reference "FWWIKYBQ6U56NL1" single access token using the resource reference FWWIKYBQ6U56NL1
received from the RS in addition to the "dolphin-metadata" resource received from the RS in addition to the dolphin-metadata resource
reference that the client instance has been configured with out of reference that the client instance has been configured with out of
band. band.
POST /tx HTTP/1.1 POST /tx HTTP/1.1
Host: server.example.com Host: server.example.com
Content-Type: application/json Content-Type: application/json
Signature-Input: sig1=... Signature-Input: sig1=...
Signature: sig1=... Signature: sig1=...
Digest: sha256=... Digest: sha256=...
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"client": "KHRS6X63AJ7C7C4AZ9AO" "client": "KHRS6X63AJ7C7C4AZ9AO"
} }
If issued, the resulting access token would contain sufficient access If issued, the resulting access token would contain sufficient access
to be used at both referenced resources. to be used at both referenced resources.
10. Acknowledgements 10. Acknowledgements
The editors would like to thank the feedback of the following The editors would like to thank the feedback of the following
individuals for their reviews, implementations, and contributions: individuals for their reviews, implementations, and contributions:
Aeke Axeland, Aaron Parecki, Adam Omar Oueidat, Annabelle Backman, Aeke Axeland, Aaron Parecki, Adam Omar Oueidat, Andrii Deinega,
Dick Hardt, Dmitri Zagidulin, Dmitry Barinov, Fabien Imbault, Francis Annabelle Backman, Dick Hardt, Dmitri Zagidulin, Dmitry Barinov,
Pouatcha, George Fletcher, Haardik Haardik, Hamid Massaoud, Jacky Fabien Imbault, Francis Pouatcha, George Fletcher, Haardik Haardik,
Yuan, Joseph Heenan, Justin Richer, Kathleen Moriarty, Mike Jones, Florian Helmschmidt, Hamid Massaoud, Jacky Yuan, Joseph Heenan,
Mike Varley, Nat Sakimura, Takahiko Kawasaki, Takahiro Tsuchiya. Justin Richer, Kathleen Moriarty, Mike Jones, Mike Varley, Nat
Sakimura, Takahiko Kawasaki, Takahiro Tsuchiya.
The editors would also like to thank the GNAP working group design The editors would also like to thank the GNAP working group design
team of Kathleen Moriarty, Fabien Imbault, Dick Hardt, Mike Jones, team of Kathleen Moriarty, Fabien Imbault, Dick Hardt, Mike Jones,
and Justin Richer, who incorporated elements from the XAuth and XYZ and Justin Richer, who incorporated elements from the XAuth and XYZ
proposals to create the first version of this document. proposals to create the first version of this document.
In addition, the editors would like to thank Aaron Parecki and Mike In addition, the editors would like to thank Aaron Parecki and Mike
Jones for insights into how to integrate identity and authentication Jones for insights into how to integrate identity and authentication
systems into the core protocol, and Justin Richer and Dick Hardt for systems into the core protocol, and Justin Richer and Dick Hardt for
the use cases, diagrams, and insights provided in the XYZ and XAuth the use cases, diagrams, and insights provided in the XYZ and XAuth
skipping to change at page 109, line 45 skipping to change at page 110, line 46
12.1. TLS Protection in Transit 12.1. TLS Protection in Transit
All requests in GNAP have to be made over TLS or equivalent as All requests in GNAP have to be made over TLS or equivalent as
outlined in [BCP195] to protect the contents of the request and outlined in [BCP195] to protect the contents of the request and
response from manipulation and interception by an attacker. This response from manipulation and interception by an attacker. This
includes all requests from a client instance to the AS, all requests includes all requests from a client instance to the AS, all requests
from the client instance to an RS, any requests back to a client from the client instance to an RS, any requests back to a client
instance such as the push-based interaction finish method, and any instance such as the push-based interaction finish method, and any
back-end communications such as from an RS to an AS as described in back-end communications such as from an RS to an AS as described in
[I-D.draft-ietf-gnap-resource-servers]. Additionally, all requests [I-D.ietf-gnap-resource-servers]. Additionally, all requests between
between a browser and other components, such as during redirect-based a browser and other components, such as during redirect-based
interaction, need to be made over TLS or use equivalent protection. interaction, need to be made over TLS or use equivalent protection.
Even though requests from the client instance to the AS are signed, Even though requests from the client instance to the AS are signed,
the signature method alone does not protect the request from the signature method alone does not protect the request from
interception by an attacker. TLS protects the response as well as interception by an attacker. TLS protects the response as well as
the request, preventing an attacker from intercepting requested the request, preventing an attacker from intercepting requested
information as it is returned. This is particularly important in the information as it is returned. This is particularly important in the
core protocol for security artifacts such as nonces and for personal core protocol for security artifacts such as nonces and for personal
information such as subject information. information such as subject information.
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software that would be otherwise unknown to the attacker. software that would be otherwise unknown to the attacker.
TLS or equivalent protection also needs to be used between the TLS or equivalent protection also needs to be used between the
browser and any other components. This applies during initial browser and any other components. This applies during initial
redirects to an AS's components during interaction, during any redirects to an AS's components during interaction, during any
interaction with the resource owner, and during any redirect back to interaction with the resource owner, and during any redirect back to
the client instance. Without TLS protection on these portions of the the client instance. Without TLS protection on these portions of the
process, an attacker could wait for a valid request to start and then process, an attacker could wait for a valid request to start and then
take over the resource owner's interaction session. take over the resource owner's interaction session.
12.2. Protection of Client Instance Key Material 12.2. Signing Requests from the Client Software
Even though all requests in GNAP need to be transmitted over TLS or
its equivalent, the use of TLS alone is not sufficient to protect all
parts of a multi-party and multi-stage protocol like GNAP, and TLS is
not targeted at tying multiple requests to each other over time. To
account for this, GNAP makes use of message-level protection and key
presentation mechanisms that strongly associate a request with a key
held by the client instance (see Section 7).
During the initial request from a client instance to the AS, the
client instance has to identify and prove possession of a
cryptographic key. If the key is known to the AS, such as if it is
previously registered or dereferenceable to a trusted source, the AS
can associate a set of policies to the client instance identified by
the key. Without the requirement that the client instance prove that
it holds that key, the AS could not trust that the connection came
from any particular client and could not apply any associated
policies.
Even more importantly, the client instance proving possession of a
key on the first request allows the AS to associate future requests
with each other. The access token used for grant continuation is
bound to the same key and proofing mechanism used by the client
instance in its initial request, which means that the client instance
needs to prove possession of that same key in future requests
allowing the AS to be sure that the same client instance is executing
the follow-ups for a given ongoing grant request. Therefore, the AS
has to ensure that all subsequent requests for a grant are associated
with the same key that started the grant, or the most recent rotation
of that key. This need holds true even if the initial key is
previously unknown to the AS, such as would be the case when a client
instance creates an ephemeral key for its request. Without this
ongoing association, an attacker would be able to impersonate a
client instance in the midst of a grant request, potentially stealing
access tokens and subject information with impunity.
Additionally, all access tokens in GNAP default to be associated with
the key that was presented during the grant request that created the
access token. This association allows an RS to know that the
presenter of the access token is the same party that the token was
issued to, as identified by their keys. While non-bound bearer
tokens are an option in GNAP, these types of tokens have their own
tradeoffs discussed elsewhere in this section.
TLS functions at the socket layer, ensuring that only the parties on
either end of that socket connection can read the information passed
along that connection. Each time a new socket connection is made,
such as for a new HTTP request, a new trust is re-established that is
unrelated to previous connections. As such, it is not possible with
TLS alone to know that the same party is making a set of calls, and
therefore TLS alone cannot provide the continuity of security needed
for GNAP. However, mutual TLS (MTLS) does provide such security
characteristics through the use of the TLS client certificate, and
thus MTLS is acceptable as a key-presentation mechanism when applied
as described in Section 7.3.2.
12.3. Protection of Client Instance Key Material
Client instances are identified by their unique keys, and anyone with Client instances are identified by their unique keys, and anyone with
access to a client instance's key material will be able to access to a client instance's key material will be able to
impersonate that client instance to all parties. This is true for impersonate that client instance to all parties. This is true for
both calls to the AS as well as calls to an RS using a key-bound both calls to the AS as well as calls to an RS using a key-bound
access token. access token.
Different types of client software have different methods available Different types of client software have different methods available
for creating, managing, and registering keys. GNAP explicitly allows for creating, managing, and registering keys. GNAP explicitly allows
for ephemeral clients, such as SPAs, and single-user clients, such as for ephemeral clients, such as SPAs, and single-user clients, such as
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between them. This situation could happen if multiple instances between them. This situation could happen if multiple instances
within a cluster can securely share secret information among within a cluster can securely share secret information among
themselves. Even though there are multiple copies of the software, themselves. Even though there are multiple copies of the software,
the shared key makes these copies all present as a single instance. the shared key makes these copies all present as a single instance.
It is considered bad practice to share keys between copies of It is considered bad practice to share keys between copies of
software unless they are very tightly integrated with each other and software unless they are very tightly integrated with each other and
can be closely managed. It is particularly bad practice to allow an can be closely managed. It is particularly bad practice to allow an
end-user to copy keys between client instances and to willingly use end-user to copy keys between client instances and to willingly use
the same key in multiple instances. the same key in multiple instances.
12.3. Protection of Authorization Server 12.4. Protection of Authorization Server
The AS performs critical functions in GNAP, including authenticating The AS performs critical functions in GNAP, including authenticating
client software, managing interactions with end-users to gather client software, managing interactions with end-users to gather
consent and provide notice, and issuing access tokens for client consent and provide notice, and issuing access tokens for client
instances to present to resource servers. As such, protecting the AS instances to present to resource servers. As such, protecting the AS
is central to any GNAP deployment. is central to any GNAP deployment.
If an attacker is able to gain control over an AS, they would be able If an attacker is able to gain control over an AS, they would be able
to create fraudulent tokens and manipulate registration information to create fraudulent tokens and manipulate registration information
to allow for malicious clients. These tokens and clients would be to allow for malicious clients. These tokens and clients would be
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If an attacker is able to impersonate an AS, they would be able to If an attacker is able to impersonate an AS, they would be able to
trick legitimate client instances into making signed requests for trick legitimate client instances into making signed requests for
information which could potentially be proxied to a real AS. To information which could potentially be proxied to a real AS. To
combat this, all communications to the AS need to be made over TLS or combat this, all communications to the AS need to be made over TLS or
its equivalent, and the software making the connection has to its equivalent, and the software making the connection has to
validate the certificate chain of the host it is connecting to. validate the certificate chain of the host it is connecting to.
Consequently, protecting, monitoring, and auditing the AS is Consequently, protecting, monitoring, and auditing the AS is
paramount to preserving the security of a GNAP-protected ecosystem. paramount to preserving the security of a GNAP-protected ecosystem.
12.4. Symmetric and Asymmetric Client Instance Keys 12.5. Symmetric and Asymmetric Client Instance Keys
The cryptographic methods used by GNAP for key-proofing can support The cryptographic methods used by GNAP for key-proofing can support
both asymmetric and symmetric cryptography, and can be extended to both asymmetric and symmetric cryptography, and can be extended to
use a wide variety of mechanisms. While symmetric cryptographic use a wide variety of mechanisms. While symmetric cryptographic
systems have some benefits in speed and simplicity, they have a systems have some benefits in speed and simplicity, they have a
distinct drawback that both parties need access to the same key in distinct drawback that both parties need access to the same key in
order to do both signing and verification of the message. This means order to do both signing and verification of the message. This means
that when the client instance calls the AS to request a token, the AS that when the client instance calls the AS to request a token, the AS
needs to know the exact value of the client instance's key (or be needs to know the exact value of the client instance's key (or be
able to derive it) in order to validate the key proof signature. able to derive it) in order to validate the key proof signature.
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be used by client instances, but only a reference to the key and not be used by client instances, but only a reference to the key and not
its value can be sent. This allows the AS to use pre-registered its value can be sent. This allows the AS to use pre-registered
symmetric keys as well as key derivation schemes to take advantage of symmetric keys as well as key derivation schemes to take advantage of
symmetric cryptography but without requiring key distribution at symmetric cryptography but without requiring key distribution at
runtime, which would expose the keys in transit. runtime, which would expose the keys in transit.
Both the AS and client software can use systems such as hardware Both the AS and client software can use systems such as hardware
security modules to strengthen their key security storage and security modules to strengthen their key security storage and
generation for both asymmetric and symmetric keys. generation for both asymmetric and symmetric keys.
12.5. Generation of Access Tokens 12.6. Generation of Access Tokens
The content of access tokens need to be such that only the generating The content of access tokens need to be such that only the generating
AS would be able to create them, and the contents cannot be AS would be able to create them, and the contents cannot be
manipulated by an attacker to gain different or additional access manipulated by an attacker to gain different or additional access
rights. rights.
One method for accomplishing this is to use a cryptographically One method for accomplishing this is to use a cryptographically
random value for the access token, generated by the AS using a secure random value for the access token, generated by the AS using a secure
randomization function with sufficiently high entropy. The odds of randomization function with sufficiently high entropy. The odds of
an attacker guessing the output of the randomization function to an attacker guessing the output of the randomization function to
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the AS can create such a signed token. The odds of an attacker being the AS can create such a signed token. The odds of an attacker being
able to guess a signature value with a useful payload are exceedingly able to guess a signature value with a useful payload are exceedingly
small. This technique only works if all targeted RS's check the small. This technique only works if all targeted RS's check the
signature of the access token. Any RS that does not validate the signature of the access token. Any RS that does not validate the
signature of all presented tokens would be susceptible to injection signature of all presented tokens would be susceptible to injection
of a modified or falsified token. Furthermore, an AS has to of a modified or falsified token. Furthermore, an AS has to
carefully protect the keys used to sign access tokens, since anyone carefully protect the keys used to sign access tokens, since anyone
with access to these signing keys would be able to create seemingly- with access to these signing keys would be able to create seemingly-
valid access tokens using them. valid access tokens using them.
12.6. Bearer Access Tokens 12.7. Bearer Access Tokens
Bearer access tokens can be used by any party that has access to the Bearer access tokens can be used by any party that has access to the
token itself, without any additional information. As a natural token itself, without any additional information. As a natural
consequence, any RS that a bearer token is presented to has the consequence, any RS that a bearer token is presented to has the
technical capability of presenting that bearer token to another RS, technical capability of presenting that bearer token to another RS,
as long as the token is valid. It also means that any party that is as long as the token is valid. It also means that any party that is
able capture of the token value in storage or in transit is able to able capture of the token value in storage or in transit is able to
use the access token. While bearer tokens are inherently simpler, use the access token. While bearer tokens are inherently simpler,
this simplicity has been misapplied and abused in making needlessly this simplicity has been misapplied and abused in making needlessly
insecure systems. insecure systems.
In GNAP, key-bound access tokens are the default due to their higher In GNAP, key-bound access tokens are the default due to their higher
security properties. While bearer tokens can be used in GNAP, their security properties. While bearer tokens can be used in GNAP, their
use should be limited onto to cases where the simplicity benefits use should be limited onto to cases where the simplicity benefits
outweigh the significant security downsides. outweigh the significant security downsides.
12.7. Key-Bound Token Access Tokens 12.8. Key-Bound Token Access Tokens
Key-bound access tokens, as the name suggests, are bound to a Key-bound access tokens, as the name suggests, are bound to a
specific key and must be presented along with proof of that key specific key and must be presented along with proof of that key
during use. The key itself is not presented at the same time as the during use. The key itself is not presented at the same time as the
token, so even if a token value is captured, it cannot be used to token, so even if a token value is captured, it cannot be used to
make a new request. This is particularly true for an RS, which will make a new request. This is particularly true for an RS, which will
see the token value but will not see the keys used to make the see the token value but will not see the keys used to make the
request. request.
Key-bound access tokens provide this additional layer of protection Key-bound access tokens provide this additional layer of protection
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Some key-bound tokens are susceptible to replay attacks, depending on Some key-bound tokens are susceptible to replay attacks, depending on
the details of the signing method used. If a signature method covers the details of the signing method used. If a signature method covers
only portions of a given request, that same signature proof can be only portions of a given request, that same signature proof can be
used by an attacker to make a similar call, potentially even varying used by an attacker to make a similar call, potentially even varying
elements that are outside of the protection of the signature. Key elements that are outside of the protection of the signature. Key
proofing mechanisms used with access tokens therefore need to use proofing mechanisms used with access tokens therefore need to use
replay protection mechanisms covered under the signature such as a replay protection mechanisms covered under the signature such as a
per-message nonce, a reasonably short time validity window, or other per-message nonce, a reasonably short time validity window, or other
uniqueness constraints. The details of using these will vary uniqueness constraints. The details of using these will vary
depending on the key proofing mechanism in use, but for example, HTTP depending on the key proofing mechanism in use, but for example, HTTP
Message Signatures has both a "created" and "nonce" signature Message Signatures has both a created and nonce signature parameter
parameter as well as the ability to cover significant portions of the as well as the ability to cover significant portions of the HTTP
HTTP message. message.
12.8. Exposure of End-user Credentials to Client Instance 12.9. Exposure of End-user Credentials to Client Instance
As a delegation protocol, one of the main goals of GNAP is to prevent As a delegation protocol, one of the main goals of GNAP is to prevent
the client software from being exposed to any credentials or the client software from being exposed to any credentials or
information about the end-user or resource owner as a requirement of information about the end-user or resource owner as a requirement of
the delegation process. By using the variety of interaction the delegation process. By using the variety of interaction
mechanisms, the resource owner can interact with the AS without ever mechanisms, the resource owner can interact with the AS without ever
authenticating to the client software, and without the client authenticating to the client software, and without the client
software having to impersonate the resource owner through replay of software having to impersonate the resource owner through replay of
their credentials. their credentials.
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possible for the client software to collect this password in a secure possible for the client software to collect this password in a secure
software enclave without exposing the password to the rest of the software enclave without exposing the password to the rest of the
client software or putting it across the wire to the AS. The AS can client software or putting it across the wire to the AS. The AS can
validate this challenge response against a known password for the validate this challenge response against a known password for the
identified end user. While an approach such as this does not remove identified end user. While an approach such as this does not remove
all of the concerns surrounding such a password-based scheme, it is all of the concerns surrounding such a password-based scheme, it is
at least possible to implement in a more secure fashion than simply at least possible to implement in a more secure fashion than simply
collecting and replaying the password. Even so, such schemes should collecting and replaying the password. Even so, such schemes should
only ever be used by trusted clients due to the ease of abusing them. only ever be used by trusted clients due to the ease of abusing them.
12.9. Mixing Up Authorization Servers 12.10. Mixing Up Authorization Servers
If a client instance is able to work with multiple AS's If a client instance is able to work with multiple AS's
simultaneously, it is more possible for an attacker to add a simultaneously, it is more possible for an attacker to add a
compromised AS to the client instance's configuration and cause the compromised AS to the client instance's configuration and cause the
client software to start a request at the compromised AS. This AS client software to start a request at the compromised AS. This AS
could then proxy the client's request to a valid AS in order to could then proxy the client's request to a valid AS in order to
attempt to get the resource owner to approve access for the attempt to get the resource owner to approve access for the
legitimate client instance. legitimate client instance.
A client instance needs to always be aware of which AS it is talking A client instance needs to always be aware of which AS it is talking
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against this kind of substitution, but only if the client instance against this kind of substitution, but only if the client instance
validates the hash. If the client instance does not use an validates the hash. If the client instance does not use an
interaction finish method or does not check the interaction finish interaction finish method or does not check the interaction finish
hash value, the compromised AS can be granted a valid access token on hash value, the compromised AS can be granted a valid access token on
behalf of the resource owner. See [attack-surfaces] for details of behalf of the resource owner. See [attack-surfaces] for details of
one such attack, which has been since addressed in this document by one such attack, which has been since addressed in this document by
including the grant endpoint in the interaction hash calculation. including the grant endpoint in the interaction hash calculation.
The client instance still needs to validate the hash for the attack The client instance still needs to validate the hash for the attack
to be prevented. to be prevented.
12.10. Processing of Client-Presented User Information 12.11. Processing of Client-Presented User Information
GNAP allows the client instance to present assertions and identifiers GNAP allows the client instance to present assertions and identifiers
of the current user to the AS as part of the initial request. This of the current user to the AS as part of the initial request. This
information should only ever be taken by the AS as a hint, since the information should only ever be taken by the AS as a hint, since the
AS has no way to tell if the represented person is present at the AS has no way to tell if the represented person is present at the
client software, without using an interaction mechanism. This client software, without using an interaction mechanism. This
information does not guarantee the given user is there, but it does information does not guarantee the given user is there, but it does
constitute a statement by the client software that the AS can take constitute a statement by the client software that the AS can take
into account. into account.
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without validating the audience of the assertion, a captured without validating the audience of the assertion, a captured
assertion could be presented by the client instance to impersonate a assertion could be presented by the client instance to impersonate a
given end user. In such cases, the assertion offers little more given end user. In such cases, the assertion offers little more
protection than a simple identifier would. protection than a simple identifier would.
A special case exists where the AS is the generator of the assertion A special case exists where the AS is the generator of the assertion
being presented by the client instance. In these cases, the AS can being presented by the client instance. In these cases, the AS can
validate that it did issue the assertion and it is associated with validate that it did issue the assertion and it is associated with
the client instance presenting the assertion. the client instance presenting the assertion.
12.11. Client Instance Pre-registration 12.12. Client Instance Pre-registration
Each client instance is identified by its own unique key, and for Each client instance is identified by its own unique key, and for
some kinds of client software such as a web server or backend system, some kinds of client software such as a web server or backend system,
this identification can be facilitated by registering a single key this identification can be facilitated by registering a single key
for a piece of client software ahead of time. This registration can for a piece of client software ahead of time. This registration can
be associated with a set of display attributes to be used during the be associated with a set of display attributes to be used during the
authorization process, identifying the client software to the user. authorization process, identifying the client software to the user.
In these cases, it can be assumed that only one instance of client In these cases, it can be assumed that only one instance of client
software will exist, likely to serve many different users. software will exist, likely to serve many different users.
A client's registration record needs to include its identifying key. A client's registration record needs to include its identifying key.
Furthermore, it is the case that any clients using symmetric Furthermore, it is the case that any clients using symmetric
cryptography for key proofing mechanisms need to have their keys pre- cryptography for key proofing mechanisms need to have their keys pre-
registered. The registration should also include any information registered. The registration should also include any information
that would aid in the authorization process, such as a display name that would aid in the authorization process, such as a display name
and logo. The registration record can also limit a given client to and logo. The registration record can also limit a given client to
ask for certain kinds of information and access, or be limited to ask for certain kinds of information and access, or be limited to
specific interaction mechanisms at runtime. specific interaction mechanisms at runtime.
It also is sensible to pre-register client instances when the It also is sensible to pre-register client instances when the
software is acting on its own behalf, without the need for a runtime software is acting autonomously, without the need for a runtime
approval by a resource owner or any interaction with an end-user. In approval by a resource owner or any interaction with an end-user. In
these cases, an AS needs to rest on the trust decisions that have these cases, an AS needs to rest on the trust decisions that have
been determined prior to runtime in determining what rights and been determined prior to runtime in determining what rights and
tokens to grant to a given client instance. tokens to grant to a given client instance.
However, it does not make sense to pre-register many types of However, it does not make sense to pre-register many types of
clients. Single-page applications (SPAs) and mobile/desktop clients. Single-page applications (SPAs) and mobile/desktop
applications in particular present problems with pre-registration. applications in particular present problems with pre-registration.
For SPAs, the instances are ephemeral in nature and long-term For SPAs, the instances are ephemeral in nature and long-term
registration of a single instance leads to significant storage and registration of a single instance leads to significant storage and
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registered. registered.
An AS can also provide warnings and caveats to resource owners during An AS can also provide warnings and caveats to resource owners during
the authorization process, allowing the user to make an informed the authorization process, allowing the user to make an informed
decision regarding the software they are authorizing. For example, decision regarding the software they are authorizing. For example,
if the AS has done vetting of the client software and this specific if the AS has done vetting of the client software and this specific
instance, it can present a different authorization screen compared to instance, it can present a different authorization screen compared to
a client instance that is presenting all of its information at a client instance that is presenting all of its information at
runtime. runtime.
12.12. Client Instance Impersonation 12.13. Client Instance Impersonation
If client instances are allowed to set their own user-facing display If client instances are allowed to set their own user-facing display
information, such as a display name and website URL, a malicious information, such as a display name and website URL, a malicious
client instance could impersonate legitimate client software for the client instance could impersonate legitimate client software for the
purposes of tricking users into authorizing the malicious client. purposes of tricking users into authorizing the malicious client.
Requiring clients to pre-register does not fully mitigate this Requiring clients to pre-register does not fully mitigate this
problem since many pre-registration systems have self-service portals problem since many pre-registration systems have self-service portals
for management of client registration, allowing authenticated for management of client registration, allowing authenticated
developers to enter self-asserted information into the management developers to enter self-asserted information into the management
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and through a registration portal, to limit the kinds of and through a registration portal, to limit the kinds of
impersonation that would be done. impersonation that would be done.
An AS can also warn the resource owner about the provenance of the An AS can also warn the resource owner about the provenance of the
information it is displaying, allowing the resource owner to make a information it is displaying, allowing the resource owner to make a
more informed delegation decision. For example, an AS can visually more informed delegation decision. For example, an AS can visually
differentiate between a client instance that can be traced back to a differentiate between a client instance that can be traced back to a
specific developer's registration and an instance that has self- specific developer's registration and an instance that has self-
asserted its own key and display information. asserted its own key and display information.
12.13. Interception of Information in the Browser 12.14. Interception of Information in the Browser
Most information passed through the web-browser is susceptible to Most information passed through the web-browser is susceptible to
interception and possible manipulation by elements within the browser interception and possible manipulation by elements within the browser
such as scripts loaded within pages. Information in the URL is such as scripts loaded within pages. Information in the URL is
exposed through browser and server logs, and can also leak to other exposed through browser and server logs, and can also leak to other
parties through HTTP "Referrer" headers. parties through HTTP Referrer headers.
GNAP's design limits the information passed directly through the GNAP's design limits the information passed directly through the
browser, allowing for opaque URLs in most circumstances. For the browser, allowing for opaque URLs in most circumstances. For the
redirect-based interaction finish mechanism, named query parameters redirect-based interaction finish mechanism, named query parameters
are used to carry unguessable opaque values. For these, GNAP are used to carry unguessable opaque values. For these, GNAP
requires creation and validation of a cryptographic hash to protect requires creation and validation of a cryptographic hash to protect
the query parameters added to the URL and associate them with an the query parameters added to the URL and associate them with an
ongoing grant process. The client instance has to properly validate ongoing grant process. The client instance has to properly validate
this hash to prevent an attacker from injecting an interaction this hash to prevent an attacker from injecting an interaction
reference intended for a different AS or client instance. reference intended for a different AS or client instance.
Several interaction start mechanisms use URLs created by the AS and Several interaction start mechanisms use URLs created by the AS and
passed to the client instance. While these URLs are opaque to the passed to the client instance. While these URLs are opaque to the
client instance, it's possible for the AS to include parameters, client instance, it's possible for the AS to include parameters,
paths, and other pieces of information that could leak security data paths, and other pieces of information that could leak security data
or be manipulated by a party in the middle of the transaction. or be manipulated by a party in the middle of the transaction.
12.14. Callback URL Manipulation 12.15. Callback URL Manipulation
The callback URL used in interaction finish mechanisms is defined by The callback URL used in interaction finish mechanisms is defined by
the client instance. This URL is opaque to the AS, but can contain the client instance. This URL is opaque to the AS, but can contain
information relevant to the client instance's operations. In information relevant to the client instance's operations. In
particular, the client instance can include state information to particular, the client instance can include state information to
allow the callback request to be associated with an ongoing grant allow the callback request to be associated with an ongoing grant
request. request.
Since this URL is exposed to the end-user's browser, it is Since this URL is exposed to the end-user's browser, it is
susceptible to both logging and manipulation in transit before the susceptible to both logging and manipulation in transit before the
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software includes a post-redirect target URL in its callback URL to software includes a post-redirect target URL in its callback URL to
the AS, this target URL could be manipulated by an attacker, creating the AS, this target URL could be manipulated by an attacker, creating
an open redirector at the client. Instead, a client instance can use an open redirector at the client. Instead, a client instance can use
an unguessable identifier into the URL that can then be used by the an unguessable identifier into the URL that can then be used by the
client software to look up the details of the pending request. Since client software to look up the details of the pending request. Since
this approach requires some form of statefulness by the client this approach requires some form of statefulness by the client
software during the redirection process, clients that are not capable software during the redirection process, clients that are not capable
of holding state through a redirect should not use redirect-based of holding state through a redirect should not use redirect-based
interaction mechanisms. interaction mechanisms.
12.15. MTLS Deployment Patterns 12.16. MTLS Message Integrity
The MTLS key proofing mechanism (Section 7.3.2) provides a means for
a client instance to present a key using a certificate the TLS layer.
Since TLS protects the entire HTTP message in transit, verification
of the TLS client certificate presented with the message provides a
sufficient binding between the two. However, since TLS is
functioning at a separate layer from HTTP, there is no direct
connection between the TLS key presentation and the message itself,
other than the fact that the message was presented over the TLS
channel. That is to say, any HTTP message can be presented over the
TLS channel in question with the same level of trust. The verifier
is responsible for ensuring the key in the TLS client certificate is
the one expected for a particular request. For example, if the
request is a grant request (request), the AS needs to compare the TLS
client certificate presented at the TLS layer to the key identified
in the request body itself (either by value or through a referenced
identifier).
Furthermore, the prevalence of the TLS-terminating reverse proxy
(TTRP) pattern in deployments adds a wrinkle to the situation. In
this common pattern, the TTRP validates the TLS connection and then
forwards the HTTP message contents onward to an internal system for
processing. The system processing the HTTP message no longer has
access to the original TLS connection's information and context. To
compensate for this, the TTRP could inject the TLS client certificate
into the forwarded request as a header parameter using
[I-D.ietf-httpbis-client-cert-field], giving the downstream system
access to the certificate information. The TTRP has to be trusted to
provide accurate certificate information, and the connection between
the TTRP and the downstream system also has to be protected. The
TTRP could provide some additional assurance, for example, by adding
its own signature to the Client-Cert header field using
[I-D.ietf-httpbis-message-signatures]. This signature would be
effectively ignored by GNAP but understood by the downstream service
as part of its deployment.
Additional considerations for different types of deployment patterns
and key distribution mechanisms for MTLS are found in Section 12.17.
12.17. MTLS Deployment Patterns
GNAP does not specify how a client instance's keys could be made GNAP does not specify how a client instance's keys could be made
known to the AS ahead of time. Public Key Infrastructure (PKI) can known to the AS ahead of time. Public Key Infrastructure (PKI) can
be used to manage the keys used by client instances when calling the be used to manage the keys used by client instances when calling the
AS, allowing the AS to trust a root key from a trusted authority. AS, allowing the AS to trust a root key from a trusted authority.
This method is particularly relevant to the MTLS signature method, This method is particularly relevant to the MTLS key proofing method,
where the client instance presents its certificate to the AS as part where the client instance presents its certificate to the AS as part
of the TLS connection. An AS using PKI to validate the MTLS of the TLS connection. An AS using PKI to validate the MTLS
connection would need to ensure that the presented certificate was connection would need to ensure that the presented certificate was
issued by a trusted certificate authority before allowing the issued by a trusted certificate authority before allowing the
connection to continue. PKI-based certificates would allow a key to connection to continue. PKI-based certificates would allow a key to
be revoked and rotated through management at the certificate be revoked and rotated through management at the certificate
authority without requiring additional registration or management at authority without requiring additional registration or management at
the AS. PKI has historically been difficult to deploy, especially at the AS. PKI has historically been difficult to deploy, especially at
scale, but it remains an appropriate solution for systems where the scale, but it remains an appropriate solution for systems where the
required overhead is not an impediment. required overhead is not an impediment.
MTLS need not use a PKI backing, as self-signed certificates and MTLS in GNAP need not use a PKI backing, as self-signed certificates
certificates from untrusted authorities can still be presented as and certificates from untrusted authorities can still be presented as
part of a TLS connection. In this case, the AS or RS would validate part of a TLS connection. In this case, the verifier would validate
the connection but accept whatever certificate was presented by the the connection but accept whatever certificate was presented by the
client software. This specific certificate would then be bound to client software. This specific certificate would then be bound to
all future connections from that client software by being bound to all future connections from that client software by being bound to
the resulting access tokens. the resulting access tokens. See Section 12.16 for more
considerations on MTLS as a key proofing mechanism.
12.16. Interception of Responses from the AS 12.18. Interception of Responses from the AS
Responses from the AS contain information vital to both the security Responses from the AS contain information vital to both the security
and privacy operations of GNAP. This information includes nonces and privacy operations of GNAP. This information includes nonces
used in cryptographic calculations, subject identifiers, assertions, used in cryptographic calculations, subject identifiers, assertions,
public keys, and information about what client software is requesting public keys, and information about what client software is requesting
and was granted. and was granted.
In addition, if bearer tokens are used or keys are issued alongside a In addition, if bearer tokens are used or keys are issued alongside a
bound access token, the response from the AS contains all information bound access token, the response from the AS contains all information
necessary for use of the contained access token. Any party that is necessary for use of the contained access token. Any party that is
capable of viewing such a response, such as an intermediary proxy, capable of viewing such a response, such as an intermediary proxy,
would be able to exfiltrate and use this token. If the access token would be able to exfiltrate and use this token. If the access token
is instead bound to the client instance's presented key, is instead bound to the client instance's presented key,
intermediaries no longer have sufficient information to use the intermediaries no longer have sufficient information to use the
token. They can still, however, gain information about the end user token. They can still, however, gain information about the end user
as well as the actions of the client software. as well as the actions of the client software.
12.17. Key Distribution 12.19. Key Distribution
The keys for client instances could be distributed as part of the The keys for client instances could be distributed as part of the
deployment process of instances of the client software. For example, deployment process of instances of the client software. For example,
an application installation framework could generate a keypair for an application installation framework could generate a keypair for
each copy of client software, then both install it into the client each copy of client software, then both install it into the client
software upon installation and registering that instance with the AS. software upon installation and registering that instance with the AS.
Additionally, it's possible for the AS to generate keys to be used Additionally, it's possible for the AS to generate keys to be used
with access tokens that are separate from the keys used by the client with access tokens that are separate from the keys used by the client
instance to request tokens. In this method, the AS would generate instance to request tokens. In this method, the AS would generate
the asymmetric keypair or symmetric key and return the entire key, the asymmetric keypair or symmetric key and return the entire key,
including all private signing information, to the client instance including all private signing information, to the client instance
alongside the access token itself. This approach would make alongside the access token itself. This approach would make
interception of the return from the token endpoint equivalent to that interception of the return from the token endpoint equivalent to that
of a bearer token, since all information required to use the access of a bearer token, since all information required to use the access
token would be present in the request. token would be present in the request.
12.18. Interaction Finish Modes and Polling 12.20. Interaction Finish Modes and Polling
During the interaction process, the client instance usually hands During the interaction process, the client instance usually hands
control of the user experience over to another component, beit the control of the user experience over to another component, beit the
system browser, another application, or some action the resource system browser, another application, or some action the resource
owner is instructed to take on another device. By using an owner is instructed to take on another device. By using an
interaction finish method, the client instance can be securely interaction finish method, the client instance can be securely
notified by the AS when the interaction is completed and the next notified by the AS when the interaction is completed and the next
phase of the protocol should occur. This process includes phase of the protocol should occur. This process includes
information that the client instance can use to validate the finish information that the client instance can use to validate the finish
call from the AS and prevent some injection, session hijacking, and call from the AS and prevent some injection, session hijacking, and
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separate device. The smart device has to poll because the expected separate device. The smart device has to poll because the expected
behavior is that the interaction will take place on the separate behavior is that the interaction will take place on the separate
device, without a way to return information to the original device's device, without a way to return information to the original device's
context. context.
As such, developers need to weigh the risks of forgoing an As such, developers need to weigh the risks of forgoing an
interaction finish method against the deployment capabilities of the interaction finish method against the deployment capabilities of the
client software and its environment. Due to the increased security, client software and its environment. Due to the increased security,
an interaction finish method should be employed whenever possible. an interaction finish method should be employed whenever possible.
12.19. Storage of Information During Interaction and Continuation 12.21. Storage of Information During Interaction and Continuation
When starting an interactive grant request, a client application has When starting an interactive grant request, a client application has
a number of protocol elements that it needs to manage, including a number of protocol elements that it needs to manage, including
nonces, references, keys, access tokens, and other elements. During nonces, references, keys, access tokens, and other elements. During
the interaction process, the client instance usually hands control of the interaction process, the client instance usually hands control of
the user experience over to another component, beit the system the user experience over to another component, beit the system
browser, another application, or some action the resource owner is browser, another application, or some action the resource owner is
instructed to take on another device. In order for the client instructed to take on another device. In order for the client
instance to make its continuation call, it will need to recall all of instance to make its continuation call, it will need to recall all of
these protocol elements. Usually this means the client instance will these protocol elements. Usually this means the client instance will
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Note that in GNAP, the client instance has to choose its interaction Note that in GNAP, the client instance has to choose its interaction
finish URL prior to making the first call to the AS. As such, the finish URL prior to making the first call to the AS. As such, the
interaction finish URL will often have a unique identifier for the interaction finish URL will often have a unique identifier for the
ongoing request, allowing the client instance to access the correct ongoing request, allowing the client instance to access the correct
portion of its storage. Since this URL is passed to other parties portion of its storage. Since this URL is passed to other parties
and often used through a browser, this URL should not contain any and often used through a browser, this URL should not contain any
security-sensitive information that would be valuable to an attacker, security-sensitive information that would be valuable to an attacker,
such as any token identifier, nonce, or user information. Instead, a such as any token identifier, nonce, or user information. Instead, a
cryptographically random value is suggested. cryptographically random value is suggested.
12.20. Denial of Service (DoS) through Grant Continuation 12.22. Denial of Service (DoS) through Grant Continuation
When a client instance starts off an interactive process, it will When a client instance starts off an interactive process, it will
eventually need to continue the grant request in a subsequent message eventually need to continue the grant request in a subsequent message
to the AS. It's possible for a naive client implementation to to the AS. It's possible for a naive client implementation to
continuously send continuation requests to the AS while waiting for continuously send continuation requests to the AS while waiting for
approval, especially if no interaction finish method is used. Such approval, especially if no interaction finish method is used. Such
constant requests could overwhelm the AS's ability to respond to both constant requests could overwhelm the AS's ability to respond to both
these and other requests. these and other requests.
To mitigate this for well-behaved client software, the continuation To mitigate this for well-behaved client software, the continuation
response contains a "wait" parameter that is intended to tell the response contains a wait parameter that is intended to tell the
client instance how long it should wait until making its next client instance how long it should wait until making its next
request. This value can be used to back off client software that is request. This value can be used to back off client software that is
checking too quickly by returning increasing wait times for a single checking too quickly by returning increasing wait times for a single
client instance. client instance.
If client software ignores the "wait" value and makes its If client software ignores the wait value and makes its continuation
continuation calls too quickly, or if the client software assumes the calls too quickly, or if the client software assumes the absence of
absence of the "wait" values means it should poll immediately, the AS the wait values means it should poll immediately, the AS can choose
can choose to return errors to the offending client instance, to return errors to the offending client instance, including possibly
including possibly canceling the ongoing grant request. With well- canceling the ongoing grant request. With well-meaning client
meaning client software these errors can indicate a need to change software these errors can indicate a need to change the client
the client software's programmed behavior. software's programmed behavior.
12.21. Exhaustion of Random Value Space 12.23. Exhaustion of Random Value Space
Several parts of the GNAP process make use of unguessable randomized Several parts of the GNAP process make use of unguessable randomized
values, such as nonces, tokens, and randomized URLs. Since these values, such as nonces, tokens, and randomized URLs. Since these
values are intended to be unique, a sufficiently powerful attacker values are intended to be unique, a sufficiently powerful attacker
could make a large number of requests to trigger generation of could make a large number of requests to trigger generation of
randomized values in an attempt to exhaust the random number randomized values in an attempt to exhaust the random number
generation space. While this attack is particularly applicable to generation space. While this attack is particularly applicable to
the AS, client software could likewise be targeted by an attacker the AS, client software could likewise be targeted by an attacker
triggering new grant requests against an AS. triggering new grant requests against an AS.
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For example, the nonces used for interaction finish hash calculation For example, the nonces used for interaction finish hash calculation
need only to be valid while the client instance is waiting for the need only to be valid while the client instance is waiting for the
finish callback and can be functionally expired when the interaction finish callback and can be functionally expired when the interaction
has completed. Similarly, artifacts like access tokens and the has completed. Similarly, artifacts like access tokens and the
interaction reference can be limited to have lifetimes tied to their interaction reference can be limited to have lifetimes tied to their
functional utility. Finally, each different category of artifact functional utility. Finally, each different category of artifact
(nonce, token, reference, identifier, etc.) can be generated from a (nonce, token, reference, identifier, etc.) can be generated from a
separate random pool of values instead of a single global value separate random pool of values instead of a single global value
space. space.
12.24. Front-channel URLs
Some interaction methods in GNAP make use of URLs accessed through
the end-user's browser, known collectively as front-channel
communication. These URLs are most notably present in the redirect
interaction start method and the redirect interaction finish mode.
Since these URLs are intended to be given to the end-user, the end
user and their browser will be subjected to anything hosted at that
URL including viruses, malware, and phishing scams. This kind of
risk is inherent to all redirection-based protocols, including GNAP
when used in this way.
When talking to a new or unknown AS, a client instance might want to
check the URL from the interaction start against a blocklist and warn
the end-user before redirecting them. Many client instances will
provide an interstitial message prior to redirection in order to
prepare the user for control of the user experience being handed to
the domain of the AS, and such a method could be used to warn the
user of potential threats. For instance, a rogue AS impersonating a
well-known service provider. Client software can also prevent this
by managing an allowlist of known and trusted AS's.
Alternatively, an attacker could start a GNAP request with a known
and trusted AS but include their own attack site URL as the callback
for the finish method. The attacker would then send the interaction
start URL to the victim and get them to click on it. Since the URL
is at the known AS, the victim is inclined to do so. The victim will
then be prompted to approve the attacker's application, and in most
circumstances the victim will then be redirected to the attacker's
site whether or not the user approved the request. The AS could
mitigate this partially by using a blocklist and allowlist of
interaction finish URLs during the client instance's initial request,
but this approach can be especially difficult if the URL has any
dynamic portion chosen by the client software. The AS can couple
these checks with policies associated with the client instance that
has been authenticated in the request. If the AS has any doubt about
the interaction finish URL, the AS can provide an interstitial
warning to the end-user before processing the redirect.
Ultimately, all protocols that use redirect-based communication
through the user's browser are susceptible to having an attacker try
to co-opt one or more of those URLs in order to harm the user. It is
the responsibility of the AS and the client software to provide
appropriate warnings, education, and mitigation to protect end users.
12.25. Processing Assertions
Identity assertions can be used in GNAP to convey subject
information, both from the AS to the client instance in a response
(Section 3.4) and from the client instance to the AS in a request
(Section 2.2). In both of these circumstances, when an assertion is
passed in GNAP, the receiver of the assertion needs to parse and
process the assertion. As assertions are complex artifacts with
their own syntax and security, special care needs to be taken to
prevent the assertion values from being used as an attack vector.
All assertion processing needs to account for the security aspects of
the assertion format in use. In particular, the processor needs to
parse the assertion from a JSON string object, and apply the
appropriate cryptographic processes to ensure the integrity of the
assertion.
For example, when SAML 2 assertions are used, the receiver hast to
parse an XML document. There are many well-known security
vulnerabilities in XML parsers, and the XML standard itself can be
attacked through the use of processing instructions and entity
expansions to cause problems with the processor. Therefore, any
system capable of processing SAML 2 assertions also needs to have a
secure and correct XML parser. In addition to this, the SAML 2
specification uses XML Signatures, which have their own
implementation problems that need to be accounted for. Similar
requirements exist for OpenID Connect's ID token, which is based on
the JSON Web Token (JWT) format and the related JSON Object Signing
And Encryption (JOSE) cryptography suite.
13. Privacy Considerations 13. Privacy Considerations
The privacy considerations in this section are modeled after the list The privacy considerations in this section are modeled after the list
of privacy threats in [[RFC6973]], "Privacy Considerations for of privacy threats in [RFC6973], "Privacy Considerations for Internet
Internet Protocols", and either explain how these threats are Protocols", and either explain how these threats are mitigated or
mitigated or advise how the threats relate to GNAP. advise how the threats relate to GNAP.
13.1. Surveillance 13.1. Surveillance
Surveillance is the observation or monitoring of an individual's Surveillance is the observation or monitoring of an individual's
communications or activities. Surveillance can be conducted by communications or activities. Surveillance can be conducted by
observers or eavesdroppers at any point along the communications observers or eavesdroppers at any point along the communications
path. path.
GNAP assumes the TLS protection used throughout the spec is intact. GNAP assumes the TLS protection used throughout the spec is intact.
Without the protection of TLS, there are many points throughout the Without the protection of TLS, there are many points throughout the
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role, the authorization server is by definition aware of each role, the authorization server is by definition aware of each
authorization of a client instance by a user. When the authorization authorization of a client instance by a user. When the authorization
server shares user information with the client instance, it needs to server shares user information with the client instance, it needs to
make sure that it has the permission from that user to do so. make sure that it has the permission from that user to do so.
Additionally, as part of the authorization grant process, the Additionally, as part of the authorization grant process, the
authorization server may be aware of which resource servers the authorization server may be aware of which resource servers the
client intends to use an access token at. However, it is possible to client intends to use an access token at. However, it is possible to
design a system using GNAP in which this knowledge is not made design a system using GNAP in which this knowledge is not made
available to the authorization server, such as by avoiding the use of available to the authorization server, such as by avoiding the use of
the "locations" object in the authorization request. the locations object in the authorization request.
If the authorization server's implementation of access tokens is such If the authorization server's implementation of access tokens is such
that it requires a resource server call back to the authorization that it requires a resource server call back to the authorization
server to validate them, then the authorization server will be aware server to validate them, then the authorization server will be aware
of which resource servers are actively in use and by which users and of which resource servers are actively in use and by which users and
which clients. To avoid this possibility, the authorization server which clients. To avoid this possibility, the authorization server
would need to structure access tokens in such a way that they can be would need to structure access tokens in such a way that they can be
validated by the resource server without notifying the authorization validated by the resource server without notifying the authorization
server that the token is being validated. server that the token is being validated.
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Unrelated resource servers also have an opportunity to correlate Unrelated resource servers also have an opportunity to correlate
users if the authorization server includes stable user identifiers in users if the authorization server includes stable user identifiers in
access tokens or in access token introspection responses. access tokens or in access token introspection responses.
In some cases a resource server may not actually need to be able to In some cases a resource server may not actually need to be able to
identify users, (such as a resource server providing access to a identify users, (such as a resource server providing access to a
company cafeteria menu which only needs to validate whether the user company cafeteria menu which only needs to validate whether the user
is a current employee), so authorization servers should be thoughtful is a current employee), so authorization servers should be thoughtful
of when user identifiers are actually necessary to communicate to of when user identifiers are actually necessary to communicate to
resource servers for the functionining of the system. resource servers for the functioning of the system.
However, note that the lack of inclusion of a user identifier in an
access token may be a risk if there is a concern that two users may
voluntarily share access tokens between them in order to access
protected resources. For example, if a website wants to limit access
to only people over 18, and such does not need to know any user
identifiers, an access token may be issued by an AS contains only the
claim "over 18". If the user is aware that this access token doesn't
reference them individually, they may be willing to share the access
token with a user who is under 18 in order to let them get access to
the website. (Note that the binding of an access token to a non-
extractable client instance key also prevents the access token from
being voluntarily shared.)
13.4.3. Correlation by Authorization Servers 13.4.3. Correlation by Authorization Servers
Clients are expected to be identified by their client instance key. Clients are expected to be identified by their client instance key.
If a particular client instance key is used at more than one If a particular client instance key is used at more than one
authorization server, this could open up the possibility for multiple authorization server, this could open up the possibility for multiple
unrelated authorization servers to correlate client instances. This unrelated authorization servers to correlate client instances. This
is especially a problem in the common case where a client instance is is especially a problem in the common case where a client instance is
used by a single individual, as it would allow the authorization used by a single individual, as it would allow the authorization
servers to correlate that individual between them. If this is a servers to correlate that individual between them. If this is a
concern of a client, the client should use distinct keys with each concern of a client, the client should use distinct keys with each
authorization server. authorization server.
13.5. Disclosure in Shared References 13.5. Disclosure in Shared References
Throughout many parts of GNAP, the parties pass shared references Throughout many parts of GNAP, the parties pass shared references
between each other, sometimes in place of the values themselves. For between each other, sometimes in place of the values themselves. For
example the "interact_ref" value used throughout the flow. These example the interact_ref value used throughout the flow. These
references are intended to be random strings and should not contain references are intended to be random strings and should not contain
any private or sensitive data that would potentially leak information any private or sensitive data that would potentially leak information
between parties. between parties.
14. References 14. References
14.1. Normative References 14.1. Normative References
[BCP195] Sheffer, Y., Holz, R., and P. Saint-Andre, [BCP195] Sheffer, Y., Holz, R., and P. Saint-Andre,
"Recommendations for Secure Use of Transport Layer "Recommendations for Secure Use of Transport Layer
Security (TLS) and Datagram Transport Layer Security Security (TLS) and Datagram Transport Layer Security
(DTLS)", May 2015, (DTLS)", May 2015,
<https://www.rfc-editor.org/info/bcp195>. <https://www.rfc-editor.org/info/bcp195>.
[I-D.draft-ietf-gnap-resource-servers] [I-D.ietf-gnap-resource-servers]
Richer, J., Parecki, A., and F. Imbault, "Grant Richer, J., Parecki, A., and F. Imbault, "Grant
Negotiation and Authorization Protocol Resource Server Negotiation and Authorization Protocol Resource Server
Connections", Work in Progress, Internet-Draft, draft- Connections", Work in Progress, Internet-Draft, draft-
ietf-gnap-resource-servers-00, 28 April 2021, ietf-gnap-resource-servers-01, 12 July 2021,
<https://www.ietf.org/archive/id/draft-ietf-gnap-resource- <https://www.ietf.org/archive/id/draft-ietf-gnap-resource-
servers-00.txt>. servers-01.txt>.
[I-D.ietf-httpbis-digest-headers]
Polli, R. and L. Pardue, "Digest Fields", Work in
Progress, Internet-Draft, draft-ietf-httpbis-digest-
headers-06, 27 September 2021,
<https://www.ietf.org/archive/id/draft-ietf-httpbis-
digest-headers-06.txt>.
[I-D.ietf-httpbis-message-signatures] [I-D.ietf-httpbis-message-signatures]
Backman, A., Richer, J., and M. Sporny, "HTTP Message Backman, A., Richer, J., and M. Sporny, "HTTP Message
Signatures", Work in Progress, Internet-Draft, draft-ietf- Signatures", Work in Progress, Internet-Draft, draft-ietf-
httpbis-message-signatures-06, 13 August 2021, httpbis-message-signatures-06, 13 August 2021,
<https://www.ietf.org/archive/id/draft-ietf-httpbis- <https://www.ietf.org/archive/id/draft-ietf-httpbis-
message-signatures-06.txt>. message-signatures-06.txt>.
[I-D.ietf-oauth-rar] [I-D.ietf-oauth-rar]
Lodderstedt, T., Richer, J., and B. Campbell, "OAuth 2.0 Lodderstedt, T., Richer, J., and B. Campbell, "OAuth 2.0
Rich Authorization Requests", Work in Progress, Internet- Rich Authorization Requests", Work in Progress, Internet-
Draft, draft-ietf-oauth-rar-07, 12 September 2021, Draft, draft-ietf-oauth-rar-08, 18 October 2021,
<https://www.ietf.org/archive/id/draft-ietf-oauth-rar- <https://www.ietf.org/archive/id/draft-ietf-oauth-rar-
07.txt>. 08.txt>.
[I-D.ietf-oauth-signed-http-request]
Richer, J., Bradley, J., and H. Tschofenig, "A Method for
Signing HTTP Requests for OAuth", Work in Progress,
Internet-Draft, draft-ietf-oauth-signed-http-request-03, 8
August 2016, <https://www.ietf.org/archive/id/draft-ietf-
oauth-signed-http-request-03.txt>.
[I-D.ietf-secevent-subject-identifiers] [I-D.ietf-secevent-subject-identifiers]
Backman, A. and M. Scurtescu, "Subject Identifiers for Backman, A. and M. Scurtescu, "Subject Identifiers for
Security Event Tokens", Work in Progress, Internet-Draft, Security Event Tokens", Work in Progress, Internet-Draft,
draft-ietf-secevent-subject-identifiers-08, 24 May 2021, draft-ietf-secevent-subject-identifiers-08, 24 May 2021,
<https://www.ietf.org/archive/id/draft-ietf-secevent- <https://www.ietf.org/archive/id/draft-ietf-secevent-
subject-identifiers-08.txt>. subject-identifiers-08.txt>.
[OIDC] Sakimura, N., Bradley, J., Jones, M., de Medeiros, B., and [OIDC] Sakimura, N., Bradley, J., Jones, M., de Medeiros, B., and
C. Mortimore, "OpenID Connect Core 1.0 incorporating C. Mortimore, "OpenID Connect Core 1.0 incorporating
errata set 1", November 2014, errata set 1", November 2014,
<https://openiD.net/specs/openiD-connect-core-1_0.html>. <https://openid.net/specs/openid-connect-core-1_0.html>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC3230] Mogul, J. and A. Van Hoff, "Instance Digests in HTTP", [RFC3230] Mogul, J. and A. Van Hoff, "Instance Digests in HTTP",
RFC 3230, DOI 10.17487/RFC3230, January 2002, RFC 3230, DOI 10.17487/RFC3230, January 2002,
<https://www.rfc-editor.org/info/rfc3230>. <https://www.rfc-editor.org/info/rfc3230>.
skipping to change at page 131, line 18 skipping to change at page 136, line 11
<https://www.rfc-editor.org/info/rfc8792>. <https://www.rfc-editor.org/info/rfc8792>.
14.2. Informative References 14.2. Informative References
[attack-surfaces] [attack-surfaces]
Axeland, Å. and O. Oueidat, "Security Analysis of Attack Axeland, Å. and O. Oueidat, "Security Analysis of Attack
Surfaces on the Grant Negotiation and Authorization Surfaces on the Grant Negotiation and Authorization
Protocol", 2021, Protocol", 2021,
<https://odr.chalmers.se/handle/20.500.12380/304105>. <https://odr.chalmers.se/handle/20.500.12380/304105>.
[I-D.ietf-httpbis-client-cert-field]
Campbell, B. and M. Bishop, "Client-Cert HTTP Header
Field: Conveying Client Certificate Information from TLS
Terminating Reverse Proxies to Origin Server
Applications", Work in Progress, Internet-Draft, draft-
ietf-httpbis-client-cert-field-00, 8 June 2021,
<https://www.ietf.org/archive/id/draft-ietf-httpbis-
client-cert-field-00.txt>.
[promise-theory] [promise-theory]
Burgess, M. and J. Bergstra, "Promise theory", January Burgess, M. and J. Bergstra, "Promise theory", January
2014, <http://markburgess.org/promises.html>. 2014, <http://markburgess.org/promises.html>.
[RFC6973] Cooper, A., Tschofenig, H., Aboba, B., Peterson, J., [RFC6973] Cooper, A., Tschofenig, H., Aboba, B., Peterson, J.,
Morris, J., Hansen, M., and R. Smith, "Privacy Morris, J., Hansen, M., and R. Smith, "Privacy
Considerations for Internet Protocols", RFC 6973, Considerations for Internet Protocols", RFC 6973,
DOI 10.17487/RFC6973, July 2013, DOI 10.17487/RFC6973, July 2013,
<https://www.rfc-editor.org/info/rfc6973>. <https://www.rfc-editor.org/info/rfc6973>.
Appendix A. Document History Appendix A. Document History
* -08
- Update definition for "Client" to account for the case of no
end-user.
- Change definition for "Subject".
- Expanded security and privacy considerations for more
situations.
- Added cross-links from security and privacy considerations.
- Editorial updates.
* -07 * -07
- Replace user handle by opaque identifier - Replace user handle by opaque identifier
- Added trust relationships - Added trust relationships
- Added privacy considerations section - Added privacy considerations section
- Added security considerations. - Added security considerations.
* -06 * -06
- Removed "capabilities" and "existing_grant" protocol fields. - Removed "capabilities" and "existing_grant" protocol fields.
- Removed separate "instance_id" field. - Removed separate "instance_id" field.
- Split "interaction_methods_supported" into - Split "interaction_methods_supported" into
"interaction_start_modes_supported" and "interaction_start_modes_supported" and
skipping to change at page 138, line 32 skipping to change at page 144, line 13
identifier to identify itself in future requests (Section 2.3.1). identifier to identify itself in future requests (Section 2.3.1).
HTTP/1.1 200 OK HTTP/1.1 200 OK
Content-Type: application/json Content-Type: application/json
Cache-Control: no-store Cache-Control: no-store
{ {
"interact": { "interact": {
"redirect": "redirect":
"https://server.example.com/interact/4CF492MLVMSW9MKM", "https://server.example.com/interact/4CF492MLVMSW9MKM",
"push": "MBDOFXG4Y5CVJCX821LH" "finish": "MBDOFXG4Y5CVJCX821LH"
} }
"continue": { "continue": {
"access_token": { "access_token": {
"value": "80UPRY5NM33OMUKMKSKU" "value": "80UPRY5NM33OMUKMKSKU"
}, },
"uri": "https://server.example.com/continue" "uri": "https://server.example.com/continue"
}, },
"instance_id": "7C7C4AZ9KHRS6X63AJAO" "instance_id": "7C7C4AZ9KHRS6X63AJAO"
} }
skipping to change at page 139, line 39 skipping to change at page 145, line 17
Content-Type: application/json Content-Type: application/json
Authorization: GNAP 80UPRY5NM33OMUKMKSKU Authorization: GNAP 80UPRY5NM33OMUKMKSKU
Signature-Input: sig1=... Signature-Input: sig1=...
Signature: sig1=... Signature: sig1=...
Digest: sha256=... Digest: sha256=...
{ {
"interact_ref": "4IFWWIKYBC2PQ6U56NL1" "interact_ref": "4IFWWIKYBC2PQ6U56NL1"
} }
The AS retrieves the pending request based on the handle and issues a The AS retrieves the pending request based on the handle and issues
bearer access token and returns this to the client instance. an access token and returns this to the client instance.
NOTE: '\' line wrapping per RFC 8792 NOTE: '\' line wrapping per RFC 8792
HTTP/1.1 200 OK HTTP/1.1 200 OK
Content-Type: application/json Content-Type: application/json
Cache-Control: no-store Cache-Control: no-store
{ {
"access_token": { "access_token": {
"value": "OS9M2PMHKUR64TB8N6BW7OZB8CDFONP219RP1LT0", "value": "OS9M2PMHKUR64TB8N6BW7OZB8CDFONP219RP1LT0",
skipping to change at page 141, line 26 skipping to change at page 147, line 26
], ],
}, },
"client": "7C7C4AZ9KHRS6X63AJAO", "client": "7C7C4AZ9KHRS6X63AJAO",
"interact": { "interact": {
"start": ["redirect", "user_code"] "start": ["redirect", "user_code"]
} }
} }
The AS processes this and determines that the RO needs to interact. The AS processes this and determines that the RO needs to interact.
The AS supports both redirect URIs and user codes for interaction, so The AS supports both redirect URIs and user codes for interaction, so
it includes both. Since there is no "callback" the AS does not it includes both. Since there is no interaction finish mode, the AS
include a nonce, but does include a "wait" parameter on the does not include a nonce, but does include a "wait" parameter on the
continuation section because it expects the client instance to poll continuation section because it expects the client instance to poll
for results. for results.
HTTP/1.1 200 OK HTTP/1.1 200 OK
Content-Type: application/json Content-Type: application/json
Cache-Control: no-store Cache-Control: no-store
{ {
"interact": { "interact": {
"redirect": "https://srv.ex/MXKHQ", "redirect": "https://srv.ex/MXKHQ",
skipping to change at page 148, line 11 skipping to change at page 154, line 11
] ]
} }
} }
D.5. Applying OAuth 2.0 Scopes and Client IDs D.5. Applying OAuth 2.0 Scopes and Client IDs
While GNAP is not designed to be directly compatible with OAuth 2.0 While GNAP is not designed to be directly compatible with OAuth 2.0
[RFC6749], considerations have been made to enable the use of OAuth [RFC6749], considerations have been made to enable the use of OAuth
2.0 concepts and constructs more smoothly within GNAP. 2.0 concepts and constructs more smoothly within GNAP.
In this scenario, the client developer has a "client_id" and set of In this scenario, the client developer has a client_id and set of
"scope" values from their OAuth 2.0 system and wants to apply them to scope values from their OAuth 2.0 system and wants to apply them to
the new protocol. Traditionally, the OAuth 2.0 client developer the new protocol. Traditionally, the OAuth 2.0 client developer
would put their "client_id" and "scope" values as parameters into a would put their client_id and scope values as parameters into a
redirect request to the authorization endpoint. redirect request to the authorization endpoint.
NOTE: '\' line wrapping per RFC 8792 NOTE: '\' line wrapping per RFC 8792
HTTP 302 Found HTTP 302 Found
Location: https://server.example.com/authorize\ Location: https://server.example.com/authorize\
?client_id=7C7C4AZ9KHRS6X63AJAO\ ?client_id=7C7C4AZ9KHRS6X63AJAO\
&scope=read%20write%20dolphin\ &scope=read%20write%20dolphin\
&redirect_uri=https://client.example.net/return\ &redirect_uri=https://client.example.net/return\
&response_type=code\ &response_type=code\
skipping to change at page 149, line 30 skipping to change at page 155, line 30
"interact": { "interact": {
"start": ["redirect"], "start": ["redirect"],
"finish": { "finish": {
"method": "redirect", "method": "redirect",
"uri": "https://client.example.net/return?state=123455", "uri": "https://client.example.net/return?state=123455",
"nonce": "LKLTI25DK82FX4T4QFZC" "nonce": "LKLTI25DK82FX4T4QFZC"
} }
} }
} }
The "client_id" can be used to identify the client instance's keys The client_id can be used to identify the client instance's keys that
that it uses for authentication, the scopes represent resources that it uses for authentication, the scopes represent resources that the
the client instance is requesting, and the "redirect_uri" and "state" client instance is requesting, and the redirect_uri and state value
value are pre-combined into a "finish" URI that can be unique per are pre-combined into a finish URI that can be unique per request.
request. The client instance additionally creates a nonce to protect The client instance additionally creates a nonce to protect the
the callback, separate from the state parameter that it has added to callback, separate from the state parameter that it has added to its
its return URL. return URL.
From here, the protocol continues as above. From here, the protocol continues as above.
Appendix E. JSON Structures and Polymorphism Appendix E. JSON Structures and Polymorphism
GNAP makes use of polymorphism within the JSON [RFC8259] structures GNAP makes use of polymorphism within the JSON [RFC8259] structures
used for the protocol. Each portion of this protocol is defined in used for the protocol. Each portion of this protocol is defined in
terms of the JSON data type that its values can take, whether it's a terms of the JSON data type that its values can take, whether it's a
string, object, array, boolean, or number. For some fields, string, object, array, boolean, or number. For some fields,
different data types offer different descriptive capabilities and are different data types offer different descriptive capabilities and are
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