draft-ietf-keyprov-dskpp-01.txt   draft-ietf-keyprov-dskpp-02.txt 
KEYPROV Working Group A. Doherty KEYPROV Working Group A. Doherty
Internet-Draft RSA, The Security Division of EMC Internet-Draft RSA, The Security Division of EMC
Intended status: Standards Track M. Pei Intended status: Standards Track M. Pei
Expires: May 1, 2008 Verisign, Inc. Expires: July 28, 2008 Verisign, Inc.
S. Machani S. Machani
Diversinet Corp. Diversinet Corp.
M. Nystrom M. Nystrom
RSA, The Security Division of EMC RSA, The Security Division of EMC
October 29, 2007 January 25, 2008
Dynamic Symmetric Key Provisioning Protocol (DSKPP) Dynamic Symmetric Key Provisioning Protocol (DSKPP)
draft-ietf-keyprov-dskpp-01.txt draft-ietf-keyprov-dskpp-02.txt
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Copyright (C) The IETF Trust (2007). Copyright (C) The IETF Trust (2008).
Abstract Abstract
DSKPP is a client-server protocol for initialization (and DSKPP is a client-server protocol for initialization (and
configuration) of symmetric keys to locally and remotely accessible configuration) of symmetric keys to locally and remotely accessible
cryptographic modules. The protocol can be run with or without cryptographic modules. The protocol can be run with or without
private-key capabilities in the cryptographic modules, and with or private-key capabilities in the cryptographic modules, and with or
without an established public-key infrastructure. without an established public-key infrastructure.
Three variations of the protocol support multiple usage scenarios. Two variations of the protocol support multiple usage scenarios. The
The four-pass (i.e., two round-trip) variant enables key generation four-pass (i.e., two round-trip) variant enables key generation in
in near real-time. With the four-pass variant, keys are mutually near real-time. With the four-pass variant, keys are mutually
generated by the provisioning server and cryptographic module; generated by the provisioning server and cryptographic module;
provisioned keys are not transferred over-the-wire or over-the-air. provisioned keys are not transferred over-the-wire or over-the-air.
Two- and one-pass variants enable secure and efficient download and The two-pass variant enables secure and efficient download and
installation of symmetric keys to a cryptographic module in installation of symmetric keys to a cryptographic module in
environments where near real-time communication may not be possible. environments where near real-time communication may not be possible.
This document builds on information contained in [RFC4758], adding This document builds on information contained in [RFC4758], adding
specific enhancements in response to implementation experience and specific enhancements in response to implementation experience and
liaison requests. It is intended, therefore, that this document or a liaison requests. It is intended that this document or a successor
successor version thereto will become the basis for subsequent version thereto will become the basis for subsequent progression of a
progression of a symmetric key provisioning protocol specification on symmetric key provisioning protocol specification on the standards
the standards track. track.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 7 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.1. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . 7 1.1. Usage Scenarios . . . . . . . . . . . . . . . . . . . . . 7
1.2. Background . . . . . . . . . . . . . . . . . . . . . . . 7 1.1.1. Single Key Request . . . . . . . . . . . . . . . . . . 7
2. Requirements Notation and Terminology . . . . . . . . . . . . 8 1.1.2. Multiple Key Requests . . . . . . . . . . . . . . . . 7
3. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . . 11 1.1.3. Session Time-Out Policy . . . . . . . . . . . . . . . 7
3.1. Single Key Request . . . . . . . . . . . . . . . . . . . 11 1.1.4. Outsourced Provisioning . . . . . . . . . . . . . . . 8
3.2. Multiple Key Requests . . . . . . . . . . . . . . . . . . 11 1.1.5. Key Renewal . . . . . . . . . . . . . . . . . . . . . 8
3.3. Session Time-Out Policy . . . . . . . . . . . . . . . . . 11 1.1.6. Pre-Loaded Key Replacement . . . . . . . . . . . . . . 8
3.4. Outsourced Provisioning . . . . . . . . . . . . . . . . . 12 1.1.7. Pre-Shared Transport Key . . . . . . . . . . . . . . . 8
3.5. Key Renewal . . . . . . . . . . . . . . . . . . . . . . . 12 1.1.8. End-to-End Protection of Key Material . . . . . . . . 9
3.6. Pre-Loaded Key Replacement . . . . . . . . . . . . . . . 12 1.2. Protocol Entities . . . . . . . . . . . . . . . . . . . . 9
3.7. Pre-Shared Transport Key . . . . . . . . . . . . . . . . 12 1.3. Initiating DSKPP . . . . . . . . . . . . . . . . . . . . . 10
3.8. SMS-Based Key Transport . . . . . . . . . . . . . . . . . 13 1.4. Determining Which Protocol Variant to Use . . . . . . . . 11
3.9. Non-Protected Transport Layer . . . . . . . . . . . . . . 13 1.4.1. Criteria for Using the Four-Pass Protocol . . . . . . 11
3.10. Non-Authenticated Transport Layer . . . . . . . . . . . . 13 1.4.2. Criteria for Using the Two-Pass Protocol . . . . . . . 12
4. DSKPP Overview . . . . . . . . . . . . . . . . . . . . . . . 13 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 12
4.1. Entities . . . . . . . . . . . . . . . . . . . . . . . . 13 2.1. Key Words . . . . . . . . . . . . . . . . . . . . . . . . 12
4.2. Overview of Protocol Usage . . . . . . . . . . . . . . . 15 2.2. Definitions . . . . . . . . . . . . . . . . . . . . . . . 12
4.3. Four-Pass Protocol Usage . . . . . . . . . . . . . . . . 18 2.3. Notation . . . . . . . . . . . . . . . . . . . . . . . . . 14
4.3.1. Message Flow . . . . . . . . . . . . . . . . . . . . 19 2.4. Abbreviations . . . . . . . . . . . . . . . . . . . . . . 15
4.3.2. Generation of Symmetric Keys for Cryptographic 3. DSKPP Protocol Details . . . . . . . . . . . . . . . . . . . . 15
3.1. Four-Pass Protocol Usage . . . . . . . . . . . . . . . . . 17
3.1.1. Message Flow . . . . . . . . . . . . . . . . . . . . . 17
3.1.2. Generation of Symmetric Keys for Cryptographic
Modules . . . . . . . . . . . . . . . . . . . . . . . 20 Modules . . . . . . . . . . . . . . . . . . . . . . . 20
4.3.3. Client Authentication . . . . . . . . . . . . . . . . 23 3.1.3. MAC Calculations . . . . . . . . . . . . . . . . . . . 22
4.3.4. Key Confirmation . . . . . . . . . . . . . . . . . . 23 3.2. Two-Pass Protocol Usage . . . . . . . . . . . . . . . . . 23
4.3.5. Server Authentication . . . . . . . . . . . . . . . . 23 3.2.1. Message Flow . . . . . . . . . . . . . . . . . . . . . 24
4.4. Two-Pass Protocol Usage . . . . . . . . . . . . . . . . . 24 3.2.2. Key Protection Profiles . . . . . . . . . . . . . . . 26
4.4.1. Message Flow . . . . . . . . . . . . . . . . . . . . 26 3.2.3. MAC Calculations . . . . . . . . . . . . . . . . . . . 30
4.4.2. Key Confirmation . . . . . . . . . . . . . . . . . . 27 3.3. User Authentication . . . . . . . . . . . . . . . . . . . 31
4.4.3. Server Authentication . . . . . . . . . . . . . . . . 27 3.3.1. Device Identifier . . . . . . . . . . . . . . . . . . 32
4.5. One-Pass Protocol Usage . . . . . . . . . . . . . . . . . 28 3.3.2. Authentication Data . . . . . . . . . . . . . . . . . 32
4.5.1. Message Flow . . . . . . . . . . . . . . . . . . . . 29 3.4. The DSKPP One-Way Pseudorandom Function, DSKPP-PRF . . . . 34
4.5.2. Key Confirmation . . . . . . . . . . . . . . . . . . 30 3.4.1. Introduction . . . . . . . . . . . . . . . . . . . . . 34
4.5.3. Server Authentication . . . . . . . . . . . . . . . . 30 3.4.2. Declaration . . . . . . . . . . . . . . . . . . . . . 35
5. Methods Common to More Than One Protocol Variant . . . . . . 31 3.5. Encryption of Pseudorandom Nonces Sent from the DSKPP
5.1. The DSKPP One-Way Pseudorandom Function, DSKPP-PRF . . . 31 Client . . . . . . . . . . . . . . . . . . . . . . . . . . 35
5.1.1. Introduction . . . . . . . . . . . . . . . . . . . . 31 4. DSKPP Message Formats . . . . . . . . . . . . . . . . . . . . 36
5.1.2. Declaration . . . . . . . . . . . . . . . . . . . . . 32 4.1. General XML Schema Requirements . . . . . . . . . . . . . 36
5.2. Encryption of Pseudorandom Nonces Sent from the DSKPP 4.2. Components of the <KeyProvTrigger> Message . . . . . . . . 36
Client (Applicable to Four-Pass and Two-Pass DSKPP) . . . 32 4.3. Components of the <KeyProvClientHello> Request . . . . . . 37
5.3. Client Authentication Mechanisms (Applicable to Four- 4.3.1. The DeviceIdentifierDataType Type . . . . . . . . . . 40
and Two-Pass DSKPP) . . . . . . . . . . . . . . . . . . . 32 4.3.2. The ProtocolVariantsType Type . . . . . . . . . . . . 40
5.3.1. Device Certificate . . . . . . . . . . . . . . . . . 33 4.3.3. The KeyContainersFormatType Type . . . . . . . . . . . 41
5.3.2. Device Identifier . . . . . . . . . . . . . . . . . . 33 4.3.4. The AuthenticationDataType Type . . . . . . . . . . . 42
5.3.3. Authentication Code . . . . . . . . . . . . . . . . . 33 4.4. Components of the <KeyProvServerHello> Response (Used
5.4. Client Authentication Examples . . . . . . . . . . . . . 36 Only in Four-Pass DSKPP) . . . . . . . . . . . . . . . . . 44
5.4.1. Example Using a MAC from an Authentication Code . . . 36 4.5. Components of a <KeyProvClientNonce> Request (Used
5.4.2. Example Using a Device Certificate . . . . . . . . . 36 Only in Four-Pass DSKPP) . . . . . . . . . . . . . . . . . 45
6. Four-Pass Protocol . . . . . . . . . . . . . . . . . . . . . 36 4.6. Components of a <KeyProvServerFinished> Response . . . . . 46
6.1. XML Basics . . . . . . . . . . . . . . . . . . . . . . . 36 4.7. The StatusCode Type . . . . . . . . . . . . . . . . . . . 48
6.2. Round-Trip #1: <KeyProvClientHello> and 5. Extensibility . . . . . . . . . . . . . . . . . . . . . . . . 50
<KeyProvServerHello> . . . . . . . . . . . . . . . . . . 37 5.1. The ClientInfoType Type . . . . . . . . . . . . . . . . . 50
6.2.1. Examples . . . . . . . . . . . . . . . . . . . . . . 37 5.2. The ServerInfoType Type . . . . . . . . . . . . . . . . . 50
6.2.2. Components of the <KeyProvClientHello> Request . . . 41 6. Protocol Bindings . . . . . . . . . . . . . . . . . . . . . . 50
6.2.3. Components of the <KeyProvServerHello> Response . . . 45 6.1. General Requirements . . . . . . . . . . . . . . . . . . . 50
6.3. Round-Trip #2: <KeyProvClientNonce> and 6.2. HTTP/1.1 Binding for DSKPP . . . . . . . . . . . . . . . . 50
<KeyProvServerFinished> . . . . . . . . . . . . . . . . . 46 6.2.1. Introduction . . . . . . . . . . . . . . . . . . . . . 50
6.3.1. Examples . . . . . . . . . . . . . . . . . . . . . . 46 6.2.2. Identification of DSKPP Messages . . . . . . . . . . . 50
6.3.2. Components of a <KeyProvClientNonce> Request . . . . 47 6.2.3. HTTP Headers . . . . . . . . . . . . . . . . . . . . . 51
6.3.3. Components of a <KeyProvServerFinished> Response . . 48 6.2.4. HTTP Operations . . . . . . . . . . . . . . . . . . . 51
6.4. DSKPP Server Results: The StatusCode Type . . . . . . . 49 6.2.5. HTTP Status Codes . . . . . . . . . . . . . . . . . . 51
7. Two-Pass Protocol . . . . . . . . . . . . . . . . . . . . . . 50 6.2.6. HTTP Authentication . . . . . . . . . . . . . . . . . 52
7.1. XML Basics . . . . . . . . . . . . . . . . . . . . . . . 50 6.2.7. Initialization of DSKPP . . . . . . . . . . . . . . . 52
7.2. Round-Trip #1: <KeyProvClientHello> and 6.2.8. Example Messages . . . . . . . . . . . . . . . . . . . 52
<KeyProvServerFinished> . . . . . . . . . . . . . . . . . 51 7. DSKPP Schema . . . . . . . . . . . . . . . . . . . . . . . . . 53
7.2.1. Examples . . . . . . . . . . . . . . . . . . . . . . 51 8. Conformance Requirements . . . . . . . . . . . . . . . . . . . 61
7.2.2. Components of the <KeyProvClientHello> Request . . . 59 9. Security Considerations . . . . . . . . . . . . . . . . . . . 62
7.2.3. Components of a <KeyProvServerFinished> Response . . 60 9.1. General . . . . . . . . . . . . . . . . . . . . . . . . . 62
7.3. DSKPP Server Results: The StatusCode Type . . . . . . . 62 9.2. Active Attacks . . . . . . . . . . . . . . . . . . . . . . 62
8. One-Pass Protocol . . . . . . . . . . . . . . . . . . . . . . 63 9.2.1. Introduction . . . . . . . . . . . . . . . . . . . . . 62
8.1. XML Basics . . . . . . . . . . . . . . . . . . . . . . . 63 9.2.2. Message Modifications . . . . . . . . . . . . . . . . 62
8.2. Server to Client Only: <KeyProvServerFinished> . . . . . 64 9.2.3. Message Deletion . . . . . . . . . . . . . . . . . . . 64
8.2.1. Example . . . . . . . . . . . . . . . . . . . . . . . 64 9.2.4. Message Insertion . . . . . . . . . . . . . . . . . . 64
8.2.2. Components of a <KeyProvServerFinished> Response . . 65 9.2.5. Message Replay . . . . . . . . . . . . . . . . . . . . 65
9. Trigger . . . . . . . . . . . . . . . . . . . . . . . . . . . 66 9.2.6. Message Reordering . . . . . . . . . . . . . . . . . . 65
9.1. XML Basics . . . . . . . . . . . . . . . . . . . . . . . 66 9.2.7. Man-in-the-Middle . . . . . . . . . . . . . . . . . . 65
9.2. Example . . . . . . . . . . . . . . . . . . . . . . . . . 67 9.3. Passive Attacks . . . . . . . . . . . . . . . . . . . . . 65
9.3. Components of the <KeyProvTrigger> Message . . . . . . . 67 9.4. Cryptographic Attacks . . . . . . . . . . . . . . . . . . 66
10. Extensibility . . . . . . . . . . . . . . . . . . . . . . . . 68 9.5. Attacks on the Interaction between DSKPP and User
10.1. The ClientInfoType Type . . . . . . . . . . . . . . . . . 68 Authentication . . . . . . . . . . . . . . . . . . . . . . 66
10.2. The ServerInfoType Type . . . . . . . . . . . . . . . . . 68 9.6. Additional Considerations . . . . . . . . . . . . . . . . 67
10.3. The KeyInitializationDataType Type . . . . . . . . . . . 68 9.6.1. Client Contributions to K_TOKEN Entropy . . . . . . . 67
11. Key Initialization Profiles of Two- and One-Pass DSKPP . . . 69 9.6.2. Key Confirmation . . . . . . . . . . . . . . . . . . . 67
11.1. Introduction . . . . . . . . . . . . . . . . . . . . . . 69 9.6.3. Server Authentication . . . . . . . . . . . . . . . . 67
11.2. Key Transport Profile . . . . . . . . . . . . . . . . . . 69 9.6.4. User Authentication . . . . . . . . . . . . . . . . . 67
11.2.1. Introduction . . . . . . . . . . . . . . . . . . . . 69 9.6.5. Key Protection in the Two-Pass Passphrase Profile . . 68
11.2.2. Identification . . . . . . . . . . . . . . . . . . . 69 10. Internationalization Considerations . . . . . . . . . . . . . 69
11.2.3. Payloads . . . . . . . . . . . . . . . . . . . . . . 69 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 69
11.3. Key Wrap Profile . . . . . . . . . . . . . . . . . . . . 70 12. Intellectual Property Considerations . . . . . . . . . . . . . 69
11.3.1. Introduction . . . . . . . . . . . . . . . . . . . . 70 13. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 69
11.3.2. Identification . . . . . . . . . . . . . . . . . . . 71 14. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 69
11.3.3. Payloads . . . . . . . . . . . . . . . . . . . . . . 71 15. References . . . . . . . . . . . . . . . . . . . . . . . . . . 70
11.4. Passphrase-Based Key Wrap Profile . . . . . . . . . . . . 72 15.1. Normative references . . . . . . . . . . . . . . . . . . . 70
11.4.1. Introduction . . . . . . . . . . . . . . . . . . . . 72 15.2. Informative references . . . . . . . . . . . . . . . . . . 71
11.4.2. Identification . . . . . . . . . . . . . . . . . . . 72 Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 72
11.4.3. Payloads . . . . . . . . . . . . . . . . . . . . . . 72 A.1. Trigger Message . . . . . . . . . . . . . . . . . . . . . 73
12. Protocol Bindings . . . . . . . . . . . . . . . . . . . . . . 73 A.2. Four-Pass Protocol . . . . . . . . . . . . . . . . . . . . 73
12.1. General Requirements . . . . . . . . . . . . . . . . . . 74 A.2.1. <KeyProvClientHello> Without a Preceding Trigger . . . 73
12.2. HTTP/1.1 Binding for DSKPP . . . . . . . . . . . . . . . 74 A.2.2. <KeyProvClientHello> Assuming a Preceding Trigger . . 74
12.2.1. Introduction . . . . . . . . . . . . . . . . . . . . 74 A.2.3. <KeyProvServerHello> Without a Preceding Trigger . . . 75
12.2.2. Identification of DSKPP Messages . . . . . . . . . . 74 A.2.4. <KeyProvServerHello> Assuming a Preceding Trigger . . 76
12.2.3. HTTP Headers . . . . . . . . . . . . . . . . . . . . 74 A.2.5. <KeyProvClientNonce> Using Default Encryption . . . . 77
12.2.4. HTTP Operations . . . . . . . . . . . . . . . . . . . 74 A.2.6. <KeyProvServerFinished> Using Default Encryption . . . 78
12.2.5. HTTP Status Codes . . . . . . . . . . . . . . . . . . 75 A.3. Two-Pass Protocol . . . . . . . . . . . . . . . . . . . . 79
12.2.6. HTTP Authentication . . . . . . . . . . . . . . . . . 75 A.3.1. Example Using the Key Transport Profile . . . . . . . 79
12.2.7. Initialization of DSKPP . . . . . . . . . . . . . . . 75 A.3.2. Example Using the Key Wrap Profile . . . . . . . . . . 82
12.2.8. Example Messages . . . . . . . . . . . . . . . . . . 75 A.3.3. Example Using the Passphrase-Based Key Wrap Profile . 85
13. DSKPP Schema . . . . . . . . . . . . . . . . . . . . . . . . 76 Appendix B. Integration with PKCS #11 . . . . . . . . . . . . . . 88
14. Security Considerations . . . . . . . . . . . . . . . . . . . 85 B.1. The 4-pass Variant . . . . . . . . . . . . . . . . . . . . 88
14.1. General . . . . . . . . . . . . . . . . . . . . . . . . . 85 B.2. The 2-pass Variant . . . . . . . . . . . . . . . . . . . . 88
14.2. Active Attacks . . . . . . . . . . . . . . . . . . . . . 85 Appendix C. Example of DSKPP-PRF Realizations . . . . . . . . . . 91
14.2.1. Introduction . . . . . . . . . . . . . . . . . . . . 85 C.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . 91
14.2.2. Message Modifications . . . . . . . . . . . . . . . . 85 C.2. DSKPP-PRF-AES . . . . . . . . . . . . . . . . . . . . . . 91
14.2.3. Message Deletion . . . . . . . . . . . . . . . . . . 87 C.2.1. Identification . . . . . . . . . . . . . . . . . . . . 91
14.2.4. Message Insertion . . . . . . . . . . . . . . . . . . 87 C.2.2. Definition . . . . . . . . . . . . . . . . . . . . . . 91
14.2.5. Message Replay . . . . . . . . . . . . . . . . . . . 87 C.2.3. Example . . . . . . . . . . . . . . . . . . . . . . . 92
14.2.6. Message Reordering . . . . . . . . . . . . . . . . . 88 C.3. DSKPP-PRF-SHA256 . . . . . . . . . . . . . . . . . . . . . 93
14.2.7. Man-in-the-Middle . . . . . . . . . . . . . . . . . . 88 C.3.1. Identification . . . . . . . . . . . . . . . . . . . . 93
14.3. Passive Attacks . . . . . . . . . . . . . . . . . . . . . 88 C.3.2. Definition . . . . . . . . . . . . . . . . . . . . . . 93
14.4. Cryptographic Attacks . . . . . . . . . . . . . . . . . . 88 C.3.3. Example . . . . . . . . . . . . . . . . . . . . . . . 94
14.5. Attacks on the Interaction between DSKPP and User Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 94
Authentication . . . . . . . . . . . . . . . . . . . . . 89 Intellectual Property and Copyright Statements . . . . . . . . . . 96
14.6. Additional Considerations Specific to 2- and 1-pass
DSKPP . . . . . . . . . . . . . . . . . . . . . . . . . . 89
14.6.1. Client Contributions to K_TOKEN Entropy . . . . . . . 89
14.6.2. Key Confirmation . . . . . . . . . . . . . . . . . . 90
14.6.3. Server Authentication . . . . . . . . . . . . . . . . 90
14.6.4. Client Authentication . . . . . . . . . . . . . . . . 90
14.6.5. Key Protection in the Passphrase Profile . . . . . . 91
15. Internationalization Considerations . . . . . . . . . . . . . 91
16. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 92
17. Intellectual Property Considerations . . . . . . . . . . . . 92
18. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 92
19. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 92
20. References . . . . . . . . . . . . . . . . . . . . . . . . . 93
20.1. Normative references . . . . . . . . . . . . . . . . . . 93
20.2. Informative references . . . . . . . . . . . . . . . . . 94
Appendix A. Integration with PKCS #11 . . . . . . . . . . . . . 95
A.1. The 4-pass Variant . . . . . . . . . . . . . . . . . . . 96
A.2. The 2-pass Variant . . . . . . . . . . . . . . . . . . . 96
A.3. The 1-pass Variant . . . . . . . . . . . . . . . . . . . 98
Appendix B. Example of DSKPP-PRF Realizations . . . . . . . . . 100
B.1. Introduction . . . . . . . . . . . . . . . . . . . . . . 101
B.2. DSKPP-PRF-AES . . . . . . . . . . . . . . . . . . . . . . 101
B.2.1. Identification . . . . . . . . . . . . . . . . . . . 101
B.2.2. Definition . . . . . . . . . . . . . . . . . . . . . 101
B.2.3. Example . . . . . . . . . . . . . . . . . . . . . . . 102
B.3. DSKPP-PRF-SHA256 . . . . . . . . . . . . . . . . . . . . 102
B.3.1. Identification . . . . . . . . . . . . . . . . . . . 102
B.3.2. Definition . . . . . . . . . . . . . . . . . . . . . 103
B.3.3. Example . . . . . . . . . . . . . . . . . . . . . . . 104
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 104
Intellectual Property and Copyright Statements . . . . . . . . . 106
1. Introduction 1. Introduction
1.1. Scope A symmetric key cryptographic module provides data authentication and
encryption services to software (or firmware) applications hosted on
This document describes a client-server protocol for initialization hardware devices, such as personal computers, handheld mobile phones,
(and configuration) of symmetric keys to locally and remotely one-time password tokens, USB flash drives, tape drives, etc. Until
accessible cryptographic modules. The protocol can be run with or recently, provisioning symmetric keys to these modules has been labor
without private-key capabilities in the cryptographic modules, and intensive, involving manual operations that are device-specific, and
with or without an established public-key infrastructure. The inherently error-prone.
objectives of this protocol are to:
o Provide a secure method of initializing cryptographic modules
with symmetric keys without exposing generated, secret material
to any other entities than the server and the cryptographic
module itself.
o Provide a secure method of generating and transporting
symmetric keys to a cryptographic module in environments where
near real-time communication is not possible.
o Provide a secure method of transporting pre-generated (i.e.,
legacy) keys to a cryptographic module.
o Provide a solution that is easy to administer and scales well.
The mechanism is intended for general use within computer and
communications systems employing symmetric key cryptographic modules
that are locally (i.e., over-the-wire) or remotely (i.e., over-the-
air) accessible.
1.2. Background
A locally accessible symmetric key cryptographic module may be hosted
by, for example, a hardware device connected to a personal computer
through an electronic interface, such as USB, or a software
application resident on a personal computer. A remotely accessible
symmetric key cryptographic module may be hosted by, for example, any
device that can support over-the-air communication, such as a hand-
held hardware device (e.g., a mobile phone). The cryptographic
module itself offers symmetric key cryptographic functionality that
may be used to authenticate a user towards some service, perform data
encryption, etc. Increasingly, these modules enable their
programmatic initialization as well as programmatic retrieval of
their output values. This document intends to meet the need for an
open and inter-operable mechanism to programmatically initialize and
configure symmetric keys to locally and remotely accessible
cryptographic modules.
The target mechanism makes use of a symmetric key provisioning
server. In an ideal deployment scenario, near real-time
communication is possible between the provisioning server and the
cryptographic module. In such an environment, it is possible for the
cryptographic module and provisioning server to mutually generate a
symmetric key, and to ensure that keys are not transported between
them.
There are, however, several deployment scenarios that make mutual key
generation less suitable. Specifically, scenarios where near real-
time communication between the symmetric key provisioning server and
the cryptographic module is not possible, and scenarios with
significant design constraints. Examples include work-flow
constraints (e.g., policies that require incremental administrative
approval), network design constraints that create network latency,
and budget constraints that sustain reliance upon legacy systems that
already have supplies of pre-generated keys. In these situations,
the cryptographic module is required to download and install a
symmetric key from the provisioning server in a secure and efficient
manner.
This document tries to meet the needs of these scenarios by
describing three variations to DSKPP for the provisioning of
symmetric keys in two round trips or less. The four-pass (i.e., two
round-trip) variant enables key generation in near real-time. With
this variant, keys are mutually generated by the provisioning server
and cryptographic module; provisioned keys are not transferred over-
the-wire or over-the-air. In contrast, two- and one-pass variants
enable secure and efficient download and installation of symmetric
keys to a cryptographic module in environments where near real-time
communication is not possible.
2. Requirements Notation and Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
The following notations are used in this document:
|| String concatenation
[x] Optional element x
A ^ B Exclusive-OR operation on strings A and B (where A
and B are of equal length)
ENC_X(Y) Encryption of message Y with symmetric key X, using a
defined block cipher
ENC_PX(Y) Encryption using message Y with a public key X
KDF_X(Y) Key derivation function that generates an arbitrary
number of octets of output using secret X and seed Y
DSKPP-PRF_X(Y,Z) Pseudo random function that generates a fixed
number Z of octets using secret X and seed Y (used in
DSKPP methods for MAC computations and key
derivation)
MAC_X(Y) Keyed message authentication code computed over Y
with symmetric key X
SIGN_x(Y) Function that provides authentication and integrity
protection of message content Y using private key x
B64(X) Base 64 encoding of string X
H(X) Hash function applied to X
Alg_List List of encryption and MAC algorithms supported by
the client
Alg_Sel Algorithms list selected by the server for the DSKPP
protocol run
DSKPP client Manages communication between the symmetric key
cryptographic module and the DSKPP server
DSKPP server The symmetric key provisioning server that
participates in the DSKPP protocol run
Issuer The organization that issues or authorizes issuance
of the symmetric key to the end user of the symmetric
key cryptographic module (e.g., a bank who issues
one-time password authentication tokens to their
retail banking users)
ID_C Identifier for DSKPP client
ID_S Identifier for DSKPP server
AUTHCODE Client Authentication Code comprised of a string of
numeric characters known to the device and the server
and containing an identifier and a password (the
AUTHCODE may be used to derive the AUTHDATA during
the DSKPP protocol exchange)
AUTHDATA Client Authentication Data that may be derived from
the AUTHCODE or using the client private key,
k_CLIENT
K Key used to encrypt R_C (either K_SERVER or K_SHARED)
K_AUTHCODE Secret key that is derived from AUTHCODE and used for
client authentication purposes
k_CLIENT Private key of the DSKPP client
K_CLIENT Public key of the DSKPP client
K_DERIVED Secret key derived from a passphrase that is known to
both the DSKPP client or user and the DSKPP server
K_MAC Secret key used for key confirmation and server
authentication purposes, and generated in DSKPP
K_MAC' A second secret key used for server authentication
purposes in 2- and 1-pass DSKPP
K_SERVER Public key of the DSKPP server
K_SHARED Secret key shared between the DSKPP client and the
DSKPP server
K_TOKEN Secret key used for cryptographic module
computations, and generated in DSKPP
K_CONFDATA Key configuration data carried within the key
container
R Pseudorandom value chosen by the DSKPP client and
used for MAC computations, which is mandatory for
2-pass DSKPP and optional for 4-pass
R_C Pseudorandom value chosen by the DSKPP client and Fortunately, an increasing number of hardware devices enable
used as input to the generation of K_TOKEN programmatic initialization of their applications. For example, a
R_S Pseudorandom value chosen by the DSKPP server and U3-ready thumb drive lets users load and configure applications
used as input to the generation of K_TOKEN locally through a USB port on their PC. Other hardware devices, such
as Personal Digital Assistant (PDA) phones, allow users to load and
configure applications over-the-air. Likewise, programmable
cryptographic modules enable issuers to provision symmetric keys via
the Internet, whether over-the-wire or over-the-air.
URL_S Server address as a URL This document describes the Dynamic Symmetric Key Provisioning
Protocol (DSKPP), which leverages these recent technological
developments. DSKPP provides an open and interoperable mechanism for
initializing and configuring symmetric keys to cryptographic modules
that are accessible over the Internet. The description is based on
the information contained in RFC4758, and contains specific
enhancements, such as User Authentication and support for the [PSKC]
format for transmission of key material.
I Unsigned integer representing a counter value that is DSKPP is a client-server protocol with two variations. One variation
monotonically increasing and guaranteed not to be establishes a symmetric key by mutually authenticated key agreement.
used again by the server towards the cryptographic The other variation relies on key distribution. In the former case,
module key agreement enables two parties (a cryptographic module and key
provisioning server) to establish a symmetric cryptographic key using
an exchange of four messages, such that the key is not transported
over the Internet. In the latter case, key distribution enables a
key provisioning server to transport a symmetric key to a
cryptographic module over the Internet using an exchange of two
messages. In either case, DSKPP is flexible enough to be run with or
without private-key capability in the cryptographic module, and with
or without an established public-key infrastructure.
I' Similar to I except I' is always higher than I All DSKPP communications consist of pairs of messages: a request and
a response. Each pair is called an "exchange", and each message sent
in an exchange is called a "pass". Thus, an implementation of DSKPP
that relies on mutually authenticated key agreement is called the
"four-pass protocol"; an implementation of DSKPP that relies on key
distribution is called the "two-pass protocol".
The following typographical convention is used in the body of the DSKPP message flow always consists of a request followed by a
text: <XMLElement>. response. It is the responsibility of the client to ensure
reliability. If the response is not received with a timeout
interval, the client needs to retransmit the request (or abandon the
connection). Number of retries and lengths of timeouts are not
covered in this document because they do not affect interoperability.
3. Use Cases 1.1. Usage Scenarios
This section describes typical use cases. DSKPP is expected to be used to provision symmetric keys to
cryptographic modules in a number of different scenarios, each with
its own special requirements.
3.1. Single Key Request 1.1.1. Single Key Request
A cryptographic module hosted by a device, such as a mobile phone, The usual scenario is that a cryptographic module makes a request for
makes a request for a symmetric key from a provisioning server. a symmetric key from a provisioning server that is located on the
Depending upon how the system is deployed, the provisioning server local network or somewhere on the Internet. Depending upon the
may generate a new key on-the-fly or use a pre-generated key, e.g., deployment scenario, the provisioning server may generate a new key
one provided by a legacy back-end issuance server. The provisioning on-the-fly or use a pre-generated key, e.g., one provided by a legacy
server assigns a unique key ID to the symmetric key and provisions it back-end issuance server. The provisioning server assigns a unique
to the cryptographic module. key ID to the symmetric key and provisions it to the cryptographic
module.
3.2. Multiple Key Requests 1.1.2. Multiple Key Requests
A cryptographic module makes multiple requests for symmetric keys A cryptographic module makes multiple requests for symmetric keys
from the same provisioning server. The symmetric keys may or may not from the same provisioning server. The symmetric keys need not be of
be of the same type, i.e., the keys may be used with different the same type, i.e., the keys may be used with different symmetric
symmetric key cryptographic algorithms, including one-time password key cryptographic algorithms, including one-time password
authentication algorithms, and AES encryption algorithm. authentication algorithms, and AES encryption algorithm.
3.3. Session Time-Out Policy 1.1.3. Session Time-Out Policy
Once a cryptographic module initiates a symmetric key request, the Once a cryptographic module initiates a symmetric key request, the
provisioning server may require that any subsequent actions to provisioning server may require that any subsequent actions to
complete the provisioning cycle occur within a certain time window. complete the provisioning cycle occur within a certain time window.
For example, an issuer may provide a time-limited authentication code For example, an issuer may provide a time-limited authentication code
to a user during registration, which the user will input into the to a user during registration, which the user will input into the
cryptographic module to authenticate themselves with the provisioning cryptographic module to authenticate themselves with the provisioning
server. If the user inputs a valid authentication code within the server. If the user inputs a valid authentication code within the
fixed time period established by the issuer, the server will allow a fixed time period established by the issuer, the server will allow a
key to be provisioned to the cryptographic module hosted by the key to be provisioned to the cryptographic module hosted by the
user's device. user's device.
3.4. Outsourced Provisioning 1.1.4. Outsourced Provisioning
A symmetric key issuer outsources its key provisioning to a third A symmetric key issuer outsources its key provisioning to a third-
party key provisioning server provider. The issuer is responsible party key provisioning server provider. The issuer is responsible
for authenticating and granting rights to users to acquire keys while for authenticating and granting rights to users to acquire keys while
acting as a proxy to the cryptographic module to acquire symmetric acting as a proxy to the cryptographic module to acquire symmetric
keys from the provisioning server; the cryptographic module keys from the provisioning server; the cryptographic module
communicates with the issuer proxy server, which forwards communicates with the issuer proxy server, which forwards
provisioning requests to the provisioning server. provisioning requests to the provisioning server.
3.5. Key Renewal 1.1.5. Key Renewal
A cryptographic module requests renewal of a symmetric key using the A cryptographic module requests renewal of a symmetric key using the
same key ID already associated with the key. Such a need may occur same key ID already associated with the key. Such a need may occur
in the case when a user wants to upgrade her device that houses the in the case when a user wants to upgrade her device that houses the
cryptographic module or when a key has expired. When a user uses the cryptographic module or when a key has expired. When a user uses the
same cryptographic module to, for example, perform strong same cryptographic module to, for example, perform strong
authentication at multiple Web login sites, keeping the same key ID authentication at multiple Web login sites, keeping the same key ID
removes the need for the user to register a new key ID at each site. removes the need for the user to register a new key ID at each site.
3.6. Pre-Loaded Key Replacement 1.1.6. Pre-Loaded Key Replacement
This use case represents a special case of symmetric key renewal in This scenario represents a special case of symmetric key renewal in
which a local administrator can authenticate the user procedurally which a local administrator can authenticate the user procedurally
before initiating the provisioning process. It also allows for an before initiating the provisioning process. It also allows for an
issuer to pre-load a key onto a cryptographic module with a issuer to pre-load a key onto a cryptographic module with a
restriction that the key is replaced with a new key prior to use of restriction that the key is replaced with a new key prior to use of
the cryptographic module. Another variation of this use case is the the cryptographic module. Another variation of this scenario is the
issuer who recycles devices. In this case, an issuer would provision issuer who recycles devices. In this case, an issuer would provision
a new symmetric key to a cryptographic module hosted on a device that a new symmetric key to a cryptographic module hosted on a device that
was previously owned by another user. was previously owned by another user.
Note that this use case is essentially the same as the last use case Note that this usage scenario is essentially the same as the last
wherein the same key ID is used for renewal. scenario wherein the same key ID is used for renewal.
3.7. Pre-Shared Transport Key 1.1.7. Pre-Shared Transport Key
A cryptographic module is loaded onto a smart card after the card is A cryptographic module is loaded onto a smart card after the card is
issued to a user. The symmetric key for the cryptographic module issued to a user. The symmetric key for the cryptographic module
will then be provisioned using a secure channel mechanism present in will then be provisioned using a secure channel mechanism present in
many smart card platforms. This allows a direct secure channel to be many smart card platforms. This allows a direct secure channel to be
established between the smart card chip and the provisioning server. established between the smart card chip and the provisioning server.
For example, the card commands (i.e., Application Protocol Data For example, the card commands (i.e., Application Protocol Data
Units, or APDUs) are encrypted with a pre-shared transport key and Units, or APDUs) are encrypted with a pre-shared transport key and
sent directly to the smart card chip, allowing secure post-issuance sent directly to the smart card chip, allowing secure post-issuance
in-the-field provisioning. This secure flow can pass Transport Layer in-the-field provisioning. This secure flow can pass Transport Layer
Security (TLS) and other transport security boundaries. Security (TLS) and other transport security boundaries.
Note that two pre-conditions for this use case are for the protocol Note that two pre-conditions for this usage scenario are for the
to be tunneled and the provisioning server to know the correct pre- protocol to be tunneled and the provisioning server to know the
established transport key. correct pre-established transport key.
3.8. SMS-Based Key Transport
A mobile device supports Short Message Service (SMS) but is not able
to support a data service allowing for HTTP or HTTPS transports. In
addition, an application may use a cryptographic module to enforce an
acceptable level of protection for download of the symmetric key via
SMS. In such a case, the cryptographic module hosted by the mobile
device may initiate a symmetric key request from a desktop computer
and ask the server to send the key to the mobile device through SMS.
User authentication is carried out via the online communication
established between the desktop computer and the provisioning server.
3.9. Non-Protected Transport Layer
Some devices are not able to support a secure transport channel such
as SSL or TLS to provide data confidentiality. A cryptographic
module hosted by such a device requests a symmetric key from the
provisioning server. It is up to DSKPP to ensure data
confidentiality over non-secure networks.
3.10. Non-Authenticated Transport Layer
Some devices are not able to use a transport protocol that provides 1.1.8. End-to-End Protection of Key Material
server authentication such as SSL or TLS. A cryptographic module
hosted by such a device wants to be sure that it sends a request for
a symmetric key to a legitimate provisioning server. It is up to
DSKPP to provide proper client and server authentication.
4. DSKPP Overview In this scenario, transport layer security does not provide end-to-
end protection of key material transported from the provisioning
server to the cryptographic module. For example, TLS may terminate
at an application hosted on a PC rather than at the cryptographic
module (i.e., the endpoint) located on a data storage device.
Mutually authenticated key agreement provides end-to-end protection,
which TLS cannot provide.
4.1. Entities 1.2. Protocol Entities
In principle, the protocol involves a DSKPP client and a DSKPP In principle, the protocol involves a DSKPP client and a DSKPP
server. The DSKPP client manages communication between the server. The DSKPP client manages communication between the
cryptographic module and the provisioning server. The DSKPP server cryptographic module and the provisioning server. In this document,
herein represents the provisioning server. the DSKPP server represents the provisioning server.
A high-level object model that describes the client-side entities and A high-level object model that describes the client-side entities and
how they relate to each other is shown in Figure 1. how they relate to each other is shown in Figure 1. Conceptually,
each entity is represented by the definitions found in Section 2.2.
----------- ------------- ----------- -------------
| User | | Device | | User | | Device |
|---------|* owns *|-----------| |---------|* owns *|-----------|
| UserID |--------->| DeviceID | | UserID |--------->| DeviceID |
| ... | | ... | | ... | | ... |
----------- ------------- ----------- -------------
| 1 | 1
| |
| contains | contains
| |
| * | *
V V
----------------------- --------------------------
|Cryptographic Module | |Cryptographic Module |
|---------------------| |------------------------|
|CryptoModuleID |Crypto Module ID |
|Encryption Algorithms| |Security Attribute List |
|MAC Algorithms |
|... | |... |
----------------------- --------------------------
| 1 | 1
| |
| contains | contains
| |
| * | *
V V
----------------------- -----------------------
|Key Container | |Key Container |
|---------------------| |---------------------|
|KeyID | |KeyID |
|Key Type | |Key Type |
|... | |... |
----------------------- -----------------------
Figure 1: Object Model Figure 1: Object Model
Conceptually, each entity represents the following: It is assumed that a device will host an application layered above
the cryptographic module, and this application will manage
communication between the DSKPP client and cryptographic module. The
manner in which the communicating application will transfer DSKPP
protocol elements to and from the cryptographic module is transparent
to the DSKPP server. One method for this transfer is described in
[CT-KIP-P11].
User: The person or client to whom devices are 1.3. Initiating DSKPP
issued
UserID: A unique identifier for the user or client To initiate DSKPP:
Device: A physical piece of hardware or software 1. A server may first send a DSKPP trigger message to a client
framework that hosts symmetric key application (e.g., in response to a user browsing to a Web site
cryptographic modules that requires a symmetric key for authentication), although this
DeviceID: A unique identifier for the device step is optional.
2. A client application calls on the DSKPP client to send a
symmetric key request to a DSKPP server, thus beginning a DSKPP
protocol run.
One of the following actions may be used to contact a DSKPP server:
1. A user may indicate how the DSKPP client is to contact a certain
DSKPP server during a browsing session.
2. A DSKPP client may be pre-configured to contact a certain DSKPP
server.
3. A user may be informed out-of-band about the location of the
DSKPP server.
Once the location of the DSKPP server is known, the DSKPP client and
the DSKPP server engage in a 4-pass or 2-pass protocol.
1.4. Determining Which Protocol Variant to Use
The four-pass and two-pass protocols are appropriate in different
deployment scenarios, as described in the sub-sections below.
1.4.1. Criteria for Using the Four-Pass Protocol
The four-pass protocol is needed under one or more of the following
conditions:
o The cryptographic module is not pre-populated with a transport
key, nor hosted on a pre-keyed device (e.g., a SIM card), nor has
a keypad that can be used for entering a passphrase (such as
present on a mobile phone).
o The hardware device will be used within multiple security domains,
which means that each domain will need to provision its own
symmetric key. However, the cryptographic module does not have a
transport key, or other type of key that can be used with multiple
provisioning servers.
o A cryptographic module does not have private-key capabilities.
o When the system provides a single point for exposing key material.
This risk can be mitigated by ensuring that both parties
contribute entropy to the key, such as with key agreement.
o A consumer of the protocol requires algorithm agility, esp. the
ability to negotiate which encryption mechanisms and key types are
used during a protocol run.
1.4.2. Criteria for Using the Two-Pass Protocol
The two-pass protocol is needed under one or more of the following
conditions:
o A device is not able to support near real-time communications.
o Pre-existing (i.e., legacy) keys must be provisioned to the
cryptographic module.
o The cryptographic module has a transport key and is capable of
performing private-key operations.
o The cryptographic module has a pre-shared key (e.g., a mobile
phone with a SIM card).\
o The cryptographic module has a keypad in which a user may enter a
passphrase, useful for deriving a key-wrapping key for
distribution of key material.
o A consumer of the protocol requires algorithm agility, esp. the
ability to negotiate which encryption mechanisms and key types are
used during a protocol run.
o Workflow dictates that an approval process is required as part of
the protocol run (e.g., for user authorization).
o Near real-time communication between the client and server is not
possible.
2. Terminology
2.1. Key Words
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
2.2. Definitions
Authentication Code (AC): Client Authentication Code comprised of a
string of numeric characters known to the device and the server
and containing an identifier and a password
Authentication Data (AD): Client Authentication Data that may be
derived from the Authentication Code (AC)
Cryptographic Module: A component of an application, which enables Cryptographic Module: A component of an application, which enables
symmetric key cryptographic functionality symmetric key cryptographic functionality
CryptoModuleID: A unique identifier for an instance of the CryptoModuleID: A unique identifier for an instance of the
cryptographic module cryptographic module
Encryption Algorithms: Encryption algorithms supported by the Device: A physical piece of hardware or software framework that
cryptographic module hosts symmetric key cryptographic modules
MAC Algorithms: MAC algorithms supported by the cryptographic Device ID (DeviceID): A unique identifier for the device
module
Key Container: An object that encapsulates a symmetric key DSKPP Client: Manages communication between the symmetric key
and its configuration data cryptographic module and the DSKPP server
KeyID: A unique identifier for the symmetric key DSKPP Server: The symmetric key provisioning server that
participates in the DSKPP protocol run
Key Type: The type of symmetric key cryptographic DSKPP Server ID (ServerID): The unique identifier of a DSKPP server
methods for which the key will be used (e.g.,
OATH HOTP or RSA SecurID authentication, AES
encryption, etc.)
It is assumed that a device will host an application layered above Key Container (KC): An object that encapsulates a symmetric key and
the cryptographic module, and this application will manage its configuration data
communication between the DSKPP client and cryptographic module. The
manner in which the communicating application will transfer DSKPP
protocol elements to and from the cryptographic module is transparent
to the DSKPP server. One method for this transfer is described in
[CT-KIP-P11].
4.2. Overview of Protocol Usage Key Container Header (KCH): Information about the Key Container,
useful for two-pass DSKPP, e.g., the ServerID and KPM
DSKPP enables symmetric key provisioning between a DSKPP server and Key ID (KeyID): A unique identifier for the symmetric key
DSKPP client. The DSKPP protocol supports the following types of
requests and responses:
<KeyProvClientHello> Key Protection Method (KPM): The key protection profile used during
two-pass DSKPP
With this request, a DSKPP client initiates contact with the Key Protection Method List (KPML): The list of key protection
DSKPP server, indicating what protocol versions and variants, methods supported by a cryptographic module
key types, encryption and MAC algorithms that it supports. In
addition, the request may include client authentication data
that the DSKPP server uses to verify proof-of-possession of
the device.
<KeyProvServerHello> Key Type: The type of symmetric key cryptographic methods for which
Upon reception of a <KeyProvClientHello> request, the DSKPP the key will be used (e.g., OATH HOTP or RSA SecurID
server uses the <KeyProvServerHello> response to specify which authentication, AES encryption, etc.)
protocol version and variant, key type, encryption algorithm,
and MAC algorithm that will be used by the DSKPP server and
DSKPP client during the protocol run. The decision of which
variant, key type, and cryptographic algorithms to pick is
policy- and implementation-dependent and therefore outside the
scope of this document.
The <KeyProvServerHello> response includes the DSKPP server's
random nonce, R_S. The response also consists of information
about either a shared secret key, or its own public key, that
the DSKPP client uses when sending its protected random nonce,
R_C, in the <KeyProvClientNonce> request (see below).
Optionally, the DSKPP server may provide a MAC that the DSKPP
client may use for server authentication.
<KeyProvClientNonce> Security Attribute List (SAL): A payload that contains the DSKPP
version, DSKPP variation (four- or two-pass), key container
formats, key types, and cryptographic algorithms that the
cryptographic module is capable of supporting
With this request, a DSKPP client and DSKPP server securely Security Context (SC): A payload that contains the DSKPP version,
exchange protected data, e.g., the protected random nonce R_C. DSKPP variation (four- or two-pass), key container format, key
In addition, the request may include client authentication type, and cryptographic algorithms relevant to the current
data that the DSKPP server uses to verify proof-of-possession protocol run
of the device. User: The person or client to whom devices are issued
<KeyProvServerFinished> User ID: A unique identifier for the user or client
The <KeyProvServerFinished> response is a confirmation message 2.3. Notation
that includes a key container that holds configuration data,
and may also contain protected key material (this depends on
the protocol variant, as discussed below).
Optionally, the DSKPP server may provide a MAC that the DSKPP
client may use for server authentication.
To initiate a DSKPP session: || String concatenation
1. A user may use a browser to connect to a web server that is
running on some host. The user may then identify (and optionally
authenticate) herself (through some means that essentially are
out of scope for this document) and request a symmetric key.
2. A client application may request a symmetric key by invoking the
DSKPP client.
3. A DSKPP server may send a trigger message to a client
application, which would then invoke the DSKPP client.
To contact the DSKPP server: [x] Optional element x
1. A user may indicate how the DSKPP client is to contact a certain A ^ B Exclusive-OR operation on strings A and B (where A
DSKPP server during a browsing session. and B are of equal length)
2. A DSKPP client may be pre-configured to contact a certain DSKPP
server. <XMLElement> A typographical convention used in the body of the
3. A user may be informed out-of-band about the location of the text
DSKPP server.
DSKPP-PRF(k,x,l) A keyed psuedo-random function (see Section 3.4)
E(k,m) Encryption of m with the key k
K Key used to encrypt R_C (either K_SERVER, K_SHARED
or K_DERIVED), or in MAC or DSKPP_PRF computations
K_AC Secret key that is derived from the Authentication
Code and used for user authentication purposes
K_CLIENT Public key of the DSKPP client
K_DERIVED Secret key derived from a passphrase that is known
to both the DSKPP client or user and the DSKPP
server
K_MAC Secret key used for key confirmation and server
authentication purposes, and generated in DSKPP
K_MAC' A second secret key used for server authentication
purposes in 2-pass DSKPP
K_SERVER Public key of the DSKPP server
K_SHARED Secret key shared between the DSKPP client and the
DSKPP server
K_TOKEN Secret key used for cryptographic module
computations, and generated in DSKPP
R Pseudorandom value chosen by the DSKPP client and
used for MAC computations
R_C Pseudorandom value chosen by the DSKPP client and
used as input to the generation of K_TOKEN
R_S Pseudorandom value chosen by the DSKPP server and
used as input to the generation of K_TOKEN
R_TRIGGER Pseudorandom value chosen by the DSKPP server and
used as input in a trigger message.
URL_S Server address as a URL
2.4. Abbreviations
AC Authentication Code
AD Authentication Data
DSKPP Dynamic Symmetric Key Provisioning Protocol
HTTP Hypertext Transfer Protocol
KC Key Container
KCH Key Container Header
KPM Key Protection Method
KPML Key Protection Method List
MAC Message Authentication Code
PC Personal Computer
PDU Protocol Data Unit
PKCS Public-Key Cryptography Standards
PRF Pseudo-Random Function
PSKC Portable Symmetric Key Container
SAL Security Attribute List (see Section 2.2)
SC Security Context (see Section 2.2)
TLS Transport Layer Security
URL Uniform Resource Locator
USB Universal Serial Bus
XML eXtensible Markup Language
3. DSKPP Protocol Details
DSKPP enables symmetric key provisioning between a DSKPP server and
DSKPP client. The DSKPP protocol supports the request and response
messages shown in Figure 2. These messages are described below.
Once the location of the DSKPP server is known, the DSKPP client and
the DSKPP server engage in a 4-pass, 2-pass, or 1-pass protocol.
Depending upon the policy and implementation, a DSKPP server selects
which variant of the protocol to use: 4-pass, 2-pass, or 1-pass.
With the four-pass variant, keys are mutually generated by the DSKPP
server and DSKPP client; provisioned keys are not transferred over-
the-wire or over-the-air. Two- and one-pass variants enable secure
and efficient download and installation of symmetric keys to a DSKPP
client in environments where near real-time communication may not be
possible.Figure 2 shows which messages get exchanged during each type
of protocol run (4-pass, 2-pass, or 1-pass).
+---------------+ +---------------+ +---------------+ +---------------+
| | | | | | | |
| DSKPP client | | DSKPP server | | DSKPP Client | | DSKPP Server |
| | | | | | | |
+---------------+ +---------------+ +---------------+ +---------------+
| | | |
| [ <---- DSKPP trigger ----- ] | | [ <--------- <KeyProvTrigger> --------- ] |
| | | |
| ------- Client Hello -------> | | ------- <KeyProvClientHello> -------> |
| (Applicable to 4- and 2-pass) | | (Applicable to 4- and 2-pass) |
| | | |
| <------ Server Hello -------- | | <------ <KeyProvServerHello> -------- |
| (Applicable to 4-pass only) | | (Applicable to 4-pass only) |
| | | |
| ------- Client Nonce -------> | | ------- <KeyProvClientNonce> -------> |
| (Applicable to 4-pass only) | | (Applicable to 4-pass only) |
| | | |
| <----- Server Finished ------ | | <---- <KeyProvServerFinished> ------- |
| (Applicable to 4-, 2-, and 1-pass) | | (Applicable to 4- and 2-pass) |
| | | |
Figure 2: The DSKPP protocol (with OPTIONAL preceding trigger) Figure 2: The DSKPP protocol (with OPTIONAL preceding trigger)
The table below identifies which protocol variants may be applied to [<KeyProvTrigger>]: A DSKPP server may initiate the DSKPP protocol
the use cases from Section 3: by sending a <KeyProvTrigger> message. For example, this message
may be sent in response to a user requesting a symmetric key in a
browsing session. The trigger message always contains a nonce to
allow the server to couple the trigger with a later
<KeyProvClientHello> request.
---------------------------------------------------------- <KeyProvClientHello>: With this request, a DSKPP client initiates
Protocol Applicable Applicable contact with the DSKPP server, indicating which protocol versions
Variant Use Cases Deployment Scenarios and variations (four-pass or two-pass), key types, encryption and
---------------------------------------------------------- MAC algorithms that it supports. In addition, the request may
4-pass All but 3.6 and Near real-time include client authentication data that the DSKPP server uses to
3.8 if mutual key communication is verify proof-of-possession of the device.
generation is desired; possible
none if transport of
a pre-generated key
2-pass All Either near real-time <KeyProvServerHello>: Upon receiving a <KeyProvClientHello> request,
or non real-time the DSKPP server uses the <KeyProvServerHello> response to
communication may be specify which protocol version and variation, key type,
possible encryption algorithm, and MAC algorithm that will be used by the
DSKPP server and DSKPP client during the protocol run. The
decision of which variation, key type, and cryptographic
algorithms to pick is policy- and implementation-dependent and
therefore outside the scope of this document.
1-pass All but 3.8 Either near real-time The <KeyProvServerHello> response includes the DSKPP server's
or non real-time random nonce, R_S. The response also consists of information
communication may be about either a shared secret key, or its own public key, that the
possible DSKPP client uses when sending its protected random nonce, R_C,
in the <KeyProvClientNonce> request (see below).
Figure 3: Mapping of protocol variants to use cases Optionally, the DSKPP server may provide a MAC that the DSKPP
client may use for server authentication.
4.3. Four-Pass Protocol Usage <KeyProvClientNonce>: With this request, a DSKPP client and DSKPP
server securely exchange protected data, e.g., the protected
random nonce R_C. In addition, the request may include client
authentication data that the DSKPP server uses to verify proof-
of-possession of the device.
The 4-pass protocol flow is suitable for environments wherein there <KeyProvServerFinished>: The <KeyProvServerFinished> response is a
is near real-time communication possible between the DSKPP client and confirmation message that includes a key container that holds
DSKPP server. It is not suitable for environments wherein configuration data, and may also contain protected key material
administrative approval is a required step in the flow, nor for (this depends on the protocol variation, as discussed below).
provisioning of pre-generated keys.
The full four-pass protocol exchange is as follows: Optionally, the DSKPP server may provide a MAC that the DSKPP
client may use for server authentication.
[<Trigger>]: 3.1. Four-Pass Protocol Usage
[ID_Device], [ID_K], [URL_S], [R_S] This section describes the message flow and methods that comprise the
four-pass protocol variant.
<KeyProvClientHello>: 3.1.1. Message Flow
[ID_Device], [ID_K], [R_S], Alg_List The four-pass protocol flow consists of two message exchanges:
<KeyProvServerHello>: 1: Pass 1 = <KeyProvClientHello>, Pass 2 = <KeyProvServerHello>
2: Pass 3 = <KeyProvClientNonce>, Pass 4 = <KeyProvServerFinished>
R_S, Alg_Sel, [K_SERVER], [DSKPP-PRF_K_MAC'("MAC 1 Computation" || The first pair of messages negotiate cryptographic algorithms and
[R] || R_S, len(R_S)) exchange nonces. The second pair of messages establishes a symmetric
key using mutually authenticated key agreement.
<KeyProvClientNonce>: The DSKPP server MUST ensure that a generated key is associated with
the correct cryptographic module, and if applicable, the correct
user. To do this, the DSKPP server MAY couple an initial user
authentication to the DSKPP execution using one of the mechanisms
described in Section 3.3.
AUTHDATA, ENC_PK_SERVER(R_C) OR AUTHDATA, ENC_K_SHARED(R_C) The purpose and content of each message are described below,
including the optional <KeyProvTrigger>.
<KeyProvServerFinished>: DSKPP Client DSKPP Server
------------ ------------
[<---] R_TRIGGER, [DeviceID],
[KeyID], [URL_S]
K_CONFDATA, DSKPP-PRF_K_MAC("MAC 2 Computation"||R_C, len(R_C)) The DSKPP server optionally sends a <KeyProvTrigger> message to the
DSKPP client. The trigger message MUST contain a nonce, R_TRIGGER,
to allow the server to couple the trigger with a later
<KeyProvClientHello> request. <KeyProvTrigger> MAY include DeviceID
to allow the client to select the device with which it will
communicate. The DeviceID MAY also be used later to authenticate the
client (see Section 3.3.1). In the case of key renewal,
<KeyProvTrigger> MAY include the identifier for the key, KeyID, that
is being replaced. Finally, the trigger MAY contain a URL for the
DSKP client to use when contacting the DSKPP server.
The following subsections describe the exchange in more detail. DSKPP Client DSKPP Server
------------ ------------
SAL, [R_TRIGGER],
[DeviceID], [KeyID] --->
4.3.1. Message Flow The DSKPP client sends a <KeyProvClientHello> message to the DSKPP
server. This message MUST contain a Security Attribute List (SAL),
identifying which DSKPP versions, protocol variations (in this case
"four-pass"), key container formats, key types, encryption and MAC
algorithms that the client supports. In addition, if a trigger
message preceded <KeyProvClientHello>, then it passes the parameters
received in <KeyProvTrigger> back to the DSKPP Server. In
particular, it MUST include R_TRIGGER so that the DSKPP server can
associate the client with the trigger message, and SHOULD include
DeviceID and KeyID.
The 4-pass protocol flow consists of two round trips between the DSKPP Client DSKPP Server
DSKPP client and DSKPP server (see Figure 2), where each round-trip ------------ ------------
involves two "passes", i.e., one request message and one response <--- SC, R_S, [K], [MAC]
message:
Round-trip #1: Pass 1 = <KeyProvClientHello>, Pass 2 = The DSKPP server responds to the DSKPP client with a
<KeyProvServerHello> <KeyProvServerHello> message, whose content MUST include a Security
Context (SC). The client will use the SC to select the DSKPP version
and variation (e.g., four-pass), type of key to generate, and
cryptographic algorithms that it will use for the remainder of the
protocol run. <KeyProvServerHello> MUST also include the server's
random nonce, R_S, whose length may depend on the selected key type.
In addition, the <KeyProvServerHello> message MAY provide K, which
represents its own public key (K_SERVER) or information about a
shared secret key (K_SHARED) to use for encrypting the cryptographic
module's random nonce (see description of <KeyProvClientNonce>
below). Optionally, <KeyProvServerHello> MAY include a MAC that the
DSKPP client can use for server authentication in the case of key
renewal (Section 3.1.3.1 describes how to calculate the MAC).
Round-trip #2: Pass 3 = <KeyProvClientNonce>, Pass 4 = DSKPP Client DSKPP Server
<KeyProvServerFinished> ------------ ------------
E(K,R_C), [AD] --->
4.3.1.1. Round-trip #1: <KeyProvClientHello> and <KeyProvServerHello> Based on the Security Context (SC) provided in the
<KeyProvServerHello> message, the cryptographic module generates a
random nonce, R_C. The length of the nonce R_C will depend on the
selected key type. The cryptographic module encrypts R_C using the
selected encryption algorithm and with a key, K, that is either the
DSKPP server's public key, K_SERVER, or a shared secret key,
K_SHARED, as indicated by the DSKPP server.
The DSKPP client sends a <KeyProvClientHello> message to the DSKPP Note: If K is equivalent to K_SERVER, then the cryptographic module
server. The message provides information to the DSKPP server about SHOULD verify the server's certificate before using it to encrypt R_C
the DSKPP versions, protocol variants, key types, encryption and MAC in accordance with [RFC3280].
algorithms supported by the cryptographic module for the purposes of
this protocol.
The DSKPP server responds to the DSKPP client with a Note: If successful execution of the protocol will result in the
<KeyProvServerHello> message, whose content includes a random nonce, replacement of an existing key with a newly generated one, the DSKPP
R_S, along with information about the type of key to generate, and client MUST verify the MAC provided in the <KeyProvServer> message.
the encryption algorithm chosen to protect sensitive data sent in the The DSKPP client MUST terminate the DSKPP session if the MAC does not
protocol. The length of the nonce R_S may depend on the selected key verify, and MUST delete any nonces, keys, and/or secrets associated
type. The <KeyProvServerHello> message also provides information with the failed run.
about either a shared secret key to use for encrypting the
cryptographic module's random nonce (see description of
<KeyProvClientNonce> below), or its own public key. Optionally,
<KeyProvServerHello> may include a MAC that the DSKPP client may use
for server authentication during key replacement.
4.3.1.2. Round-trip #2: <KeyProvClientNonce> and The DSKPP client MUST send the encrypted random nonce to the DSKPP
<KeyProvServerFinished> server in a <KeyProvClientNonce> message, and MAY include client
Authentication Data (AD), such as a MAC derived from an
authentication code and R_C (refer to Section 3.3.2). Finally, the
cryptographic module calculates and stores a symmetric key, K_TOKEN,
of the key type specified in the SC received in <KeyProvServerHello>
(refer to Section 3.1.2.2.<KeyProvServerFinished> for a description
of how K_TOKEN is generated).
Based on information contained in the <KeyProvServerHello> message, DSKPP Client DSKPP Server
the cryptographic module generates a random nonce, R_C. The length of ------------ ------------
the nonce R_C may depend on the selected key type. The cryptographic <--- KC, MAC
module encrypts R_C using the selected encryption algorithm and with
a key, K, that is either the DSKPP server's public key, K_SERVER, or
a shared secret key, K_SHARED, as indicated by the DSKPP server. If
K is equivalent to K_SERVER, then the cryptographic module SHOULD
verify the server's certificate before using it to encrypt R_C in
accordance with [RFC3280]. The DSKPP client then sends the encrypted
random nonce to the DSKPP server in a <KeyProvClientNonce> message,
and may include client authentication data, such as a certificate or
MAC derived from an authentication code and R_C. Finally, the
cryptographic module calculates a symmetric key, K_TOKEN, of the
selected type from the combination of the two random nonces R_S and
R_C, the encryption key K, and possibly some other data, using the
DSKPP-PRF function defined in Section 5.1.
The DSKPP server decrypts R_C, calculates K_TOKEN from the If Authentication Data (AD) was received in the <KeyProvClientNonce>
combination of the two random nonces R_S and R_C, the encryption key message, then the DSKPP server MUST authenticate the user in
K, and possibly some other data, using the DSKPP-PRF function defined accordance with Section 3.3.2. If authentication fails, then DSKPP
in Section 5.1. The server then associates K_TOKEN with the server MUST abort. Otherwise, the DSKPP server decrypts R_C,
cryptographic module in a server-side data store. The intent is that calculates K_TOKEN from the combination of the two random nonces R_S
the data store later on will be used by some service that needs to and R_C, the encryption key K, and possibly some other data, using
verify or decrypt data produced by the cryptographic module and the the DSKPP-PRF function defined in Section 3.4. The server then
key. associates K_TOKEN with the cryptographic module in a server-side
data store. The intent is that the data store later on will be used
by some service that needs to verify or decrypt data produced by the
cryptographic module and the key.
Once the association has been made, the DSKPP server sends a Once the association has been made, the DSKPP server sends a
confirmation message to the DSKPP client called confirmation message to the DSKPP client called
<KeyProvServerFinished>. Optionally, <KeyProvServerFinished> may <KeyProvServerFinished>. The confirmation message MUST include a Key
include a MAC that the DSKPP client may use for server Container (KC) that holds an identifier for the generated key (but
authentication. The confirmation message includes a key container not the key itself) and additional configuration information, e.g.,
that holds an identifier for the generated key (but not the key the identity of the DSKPP server. The default symmetric key
itself) and additional configuration information, e.g., the identity container format is based on the Portable Symmetric Key Container
of the DSKPP server. The default symmetric key container format that (PSKC) defined in [PSKC]. Alternative formats MAY include PKCS#12
is used in the <KeyProvServerFinished> message is based on the [PKCS-12] or PKCS#5 XML [PKCS-5-XML] format. In addition to a Key
Portable Symmetric Key Container (PSKC) defined in [PSKC]. Container, <KeyProvServerFinished> MUST also include a MAC that the
Alternative formats MAY include PKCS#12 [PKCS-12] or PKCS#5 XML DSKPP client will use to authenticate the message before commiting
[PKCS-5-XML] format. K_TOKEN.
Upon receipt of the DSKPP server's confirmation message, the After receiving a <KeyProvServerFinished> message with Status =
cryptographic module associates the provided key container with the "Success", the DSKPP client MUST verify the MAC. The DSKPP client
generated key K_TOKEN, and stores any provided configuration data. MUST terminate the DSKPP session if the MAC does not verify, and
MUST, in this case, also delete any nonces, keys, and/or secrets
associated with the failed run of the protocol. If
<KeyProvServerFinished> has Status = "Success" and the MAC was
verified, then the DSKPP client MUST associate the provided key
container with the generated key K_TOKEN, and store this data
permanently. After this operation, it MUST NOT be possible to
overwrite the key unless knowledge of an authorizing key is proven
through a MAC on a later <KeyProvServerHello> (and
<KeyProvServerFinished>) message.
4.3.2. Generation of Symmetric Keys for Cryptographic Modules 3.1.2. Generation of Symmetric Keys for Cryptographic Modules
With 4-pass DSKPP, the symmetric key that is the target of With 4-pass DSKPP, the symmetric key that is the target of
provisioning, is generated on-the-fly without being transferred provisioning, is generated on-the-fly without being transferred
between the DSKPP client and DSKPP server. A sample data flow between the DSKPP client and DSKPP server. A sample data flow
depicting how this works followed by computational information are depicting how this works followed by computational information are
provided in the subsections below. provided in the subsections below.
4.3.2.1. Data Flow 3.1.2.1. Data Flow
A sample data flow showing key generation during the 4-pass protocol A sample data flow showing key generation during the 4-pass protocol
is shown in Figure 4. is shown in Figure 8.
+----------------------+ +-------+ +----------------------+ +----------------------+ +-------+ +----------------------+
| +------------+ | | | | | | +------------+ | | | | |
| | Server key | | | | | | | | Server key | | | | | |
| +<-| Public |------>------------->-------------+---------+ | | +<-| Public |------>------------->-------------+---------+ |
| | | Private | | | | | | | | | | | Private | | | | | | | |
| | +------------+ | | | | | | | | | +------------+ | | | | | | |
| | | | | | | | | | | | | | | | | | | |
| V V | | | | V V | | V V | | | | V V |
| | +---------+ | | | | +---------+ | | | | +---------+ | | | | +---------+ | |
| | | Decrypt |<-------<-------------<-----------| Encrypt | | | | | | Decrypt |<-------<-------------<-----------| Encrypt | | |
skipping to change at page 21, line 43 skipping to change at page 21, line 39
| +-------+ | | | | +-------+ | | +-------+ | | | | +-------+ |
| | Key | | | | | | Key | | | | Key | | | | | | Key | |
| +-------+ | | | | +-------+ | | +-------+ | | | | +-------+ |
| +-------+ | | | | +-------+ | | +-------+ | | | | +-------+ |
| |Key Id |-------->------------->------|Key Id | | | |Key Id |-------->------------->------|Key Id | |
| +-------+ | | | | +-------+ | | +-------+ | | | | +-------+ |
+----------------------+ +-------+ +----------------------+ +----------------------+ +-------+ +----------------------+
DSKPP Server DSKPP Client DSKPP Client DSKPP Server DSKPP Client DSKPP Client
(PC Host) (cryptographic module) (PC Host) (cryptographic module)
Figure 4: Principal data flow for DSKPP key generation - Figure 8: Principal data flow for DSKPP key generation -
using public server key using public server key
Note: Conceptually, although R_C is one pseudorandom string, it may Note: Conceptually, although R_C is one pseudorandom string, it may
be viewed as consisting of two components, R_C1 and R_C2, where R_C1 be viewed as consisting of two components, R_C1 and R_C2, where R_C1
is generated during the protocol run, and R_C2 can be pre-generated is generated during the protocol run, and R_C2 can be pre-generated
and loaded on the cryptographic module before the device is issued to and loaded on the cryptographic module before the device is issued to
the user. In that case, the latter string, R_C2, SHOULD be unique the user. In that case, the latter string, R_C2, SHOULD be unique
for each cryptographic module. for each cryptographic module.
The inclusion of the two random nonces R_S and R_C in the key The inclusion of the two random nonces R_S and R_C in the key
skipping to change at page 22, line 30 skipping to change at page 22, line 25
else the attacker would not be able to decrypt the information else the attacker would not be able to decrypt the information
received from the client). Therefore, once the attacker is no longer received from the client). Therefore, once the attacker is no longer
"in the middle," the client and server will detect that they are "out "in the middle," the client and server will detect that they are "out
of sync" when they try to use their keys. In the case of encrypting of sync" when they try to use their keys. In the case of encrypting
R_C with K_SERVER, it is therefore important to verify that K_SERVER R_C with K_SERVER, it is therefore important to verify that K_SERVER
really is the legitimate server's key. One way to do this is to really is the legitimate server's key. One way to do this is to
independently validate a newly generated K_TOKEN against some independently validate a newly generated K_TOKEN against some
validation service at the server (e.g. by using a connection validation service at the server (e.g. by using a connection
independent from the one used for the key generation). independent from the one used for the key generation).
4.3.2.2. Computing the Symmetric Key 3.1.2.2. Computing the Symmetric Key
In DSKPP, keys are generated using the DSKPP-PRF function defined in In DSKPP, keys are generated using the DSKPP-PRF function defined in
Section 5.1, a secret random value R_C chosen by the DSKPP client, a Section 3.4, a secret random value R_C chosen by the DSKPP client, a
random value R_S chosen by the DSKPP server, and the key k used to random value R_S chosen by the DSKPP server, and the key K used to
encrypt R_C. The input parameter s of DSKPP-PRF is set to the encrypt R_C. The input parameter s of DSKPP-PRF is set to the
concatenation of the (ASCII) string "Key generation", k, and R_S, and concatenation of the (ASCII) string "Key generation", K, and R_S, and
the input parameter dsLen is set to the desired length of the key, the input parameter dsLen is set to the desired length of the key,
K_TOKEN (the length of K_TOKEN is given by the key's type): K_TOKEN (the length of K_TOKEN is given by the key's type):
dsLen = (desired length of K_TOKEN) dsLen = (desired length of K_TOKEN)
K_TOKEN = DSKPP-PRF (R_C, "Key generation" || k || R_S, dsLen) K_TOKEN = DSKPP-PRF (R_C, "Key generation" || K || R_S, dsLen)
When computing K_TOKEN above, the output of DSKPP-PRF MAY be subject When computing K_TOKEN above, the output of DSKPP-PRF MAY be subject
to an algorithm-dependent transform before being adopted as a key of to an algorithm-dependent transform before being adopted as a key of
the selected type. One example of this is the need for parity in DES the selected type. One example of this is the need for parity in DES
keys. keys.
4.3.3. Client Authentication 3.1.3. MAC Calculations
To ensure that a generated key K_TOKEN ends up associated with the
correct cryptographic module and user, the DSKPP client using any of
the methods described in Section 5.3. Whatever the method, the DSKPP
server MUST ensure that a generated key is associated with the
correct cryptographic module, and if applicable, the correct user.
4.3.4. Key Confirmation
In four-pass DSKPP, the client includes a nonce R_C in the
<KeyProvClientHello> message. The MAC value in the
<KeyProvServerFinished> message MUST be computed on the (ASCII)
string "MAC 2 computation", the client nonce R_C using a MAC key
K_MAC. This key MUST be generated together with K_TOKEN using R_C
and R_S.
The MAC value in <KeyProvServerFinished> MAY be computed by using the 3.1.3.1. Server Authorization in the Case of Key Renewal
DSKPP-PRF function of Section 5.1, in which case the input parameter
s MUST consist of the concatenation of the (ASCII) string "MAC 2
computation", R_C, the parameter dsLen MUST be set to the length of
R_C:
dsLen = len(R_C) A MAC MUST be present in the <KeyProvServerHello> message if the
DSKPP run will result in the replacement of an existing key with a
new one as proof that the DSKPP server is authorized to perform the
action. When the MAC value is used for server authentication, the
value MAY be computed by using the DSKPP-PRF function of Section 3.4,
in which case the input parameter s MUST be set to the concatenation
of the (ASCII) string "MAC 1 computation", R (if sent by the client),
and R_S, and K MUST be set to the existing MAC key K_MAC' . The
input parameter dsLen MUST be set to the length of R_S:
MAC = DSKPP-PRF (K_MAC, "MAC 2 computation" || R_C, dsLen) dsLen = len(R_S)
4.3.5. Server Authentication MAC = DSKPP-PRF (K_MAC', "MAC 1 computation" || [R ||] R_S, dsLen)
A DSKPP server MUST authenticate itself to avoid a false "Commit" of 3.1.3.2. Key Confirmation
a symmetric key that which could cause the cryptographic module to
end up in an initialized state for which the server does not know the
stored key. To do this, the DSKPP server authenticates itself by
including a MAC value in the <KeyProvServerHello> message when
replacing a existing key. The MAC value is generated using the
existing the MAC key K_MAC' (the MAC key that existed before this
protocol run). The MAC algorithm MUST be the same as the algorithm
used for key confirmation purposes. In addition, a DSKPP server can
leverage transport layer authentication if it is available.
When the MAC value is used for server authentication, the value MAY To avoid a false "Commit" message causing the cryptographic module to
be computed by using the DSKPP-PRF function of Section 5.1, in which end up in an initialized state in which the server does not recognize
case the input parameter s MUST be set to the concatenation of the the stored key, <ServerFinished> messages MUST be authenticated with
(ASCII) string "MAC 1 computation", R (if sent by the client), and a MAC. The MAC MUST be calculated using the already established MAC
R_S, and k MUST be set to the existing MAC key K_MAC' . The input algorithm and MUST be computed on the (ASCII) string "MAC 2
parameter dsLen MUST be set to the length of R_S: computation" and R_C using the existing the MAC key K_MAC' (i.e., the
MAC key that existed before this protocol run). If DSKPP-PRFof
Section 3.4 is used as the MAC algorithm, then the input parameter s
MUST consist of the concatenation of the (ASCII) string "MAC 2
computation", R_C, and dsLen as follows:
dsLen = len(R_S) dsLen = len(R_C)
MAC = DSKPP-PRF (K_MAC', "MAC 1 computation" || [R ||] R_S, dsLen)
4.4. Two-Pass Protocol Usage MAC = DSKPP-PRF (K_MAC, "MAC 2 computation" || R_C, dsLen)
The 2-pass protocol flow is suitable for environments wherein near 3.2. Two-Pass Protocol Usage
real-time communication between the DSKPP client and server may not
be possible. It is also suitable for environments wherein
administrative approval is a required step in the flow, and for
provisioning of pre-generated keys. In the 2-pass protocol flow, the
client's initial <KeyProvClientHello> message is directly followed by
a <KeyProvServerFinished> message. There is no exchange of the
<KeyProvServerHello> message or the <KeyProvClientNonce> message.
However, as the two-pass variant of DSKPP consists of one round trip
to the server, the client is still able to include its random nonce,
R_C, algorithm preferences and supported key types in the
<KeyProvClientHello> message. Note that by including R_C in
<KeyProvClientHello>, the DSKPP client is able to ensure the server
is alive before "committing" the key. Also note that the DSKPP
"trigger" message MAY be used to trigger the client's sending of the
<KeyProvClientHello> message.
Essentially, two-pass DSKPP is a transport of key material from the Two-pass DSKPP is essentially a transport of key material from the
DSKPP server to the DSKPP client. Two-pass DSKPP supports multiple DSKPP server to the DSKPP client. Two-pass DSKPP supports multiple
key initialization methods that ensure K_TOKEN is not exposed to any key protection methods that ensure K_TOKEN is not exposed to any
other entity than the DSKPP server and the cryptographic module other entity than the DSKPP server and the cryptographic module
itself. Currently, three such key initialization methods are defined itself. Currently, three such key protection methods are defined
(refer to Section 11), each supporting a different usage of 2-pass (refer to Section 3.2.2), each supporting a different usage of 2-pass
DSKPP: DSKPP:
Key Transport This profile is intended for PKI-capable Key Transport This profile is intended for PKI-capable
devices. Key transport is carried out devices. Key transport is carried out
using a public key, K_CLIENT, whose using a public key, K_CLIENT, whose
private key part resides in the private key part resides in the
cryptographic module as the transport cryptographic module as the transport
key. key.
Key Wrap This profile is ideal for pre-keyed Key Wrap This profile is ideal for pre-keyed
devices, e.g., SIM cards. Key wrap is devices, e.g., SIM cards. Key wrap is
carried out using a symmetric key- carried out using a symmetric key-
wrapping key, K_SHARED, which is known in wrapping key, K_SHARED, which is known in
advance by both the cryptographic module advance by both the cryptographic module
and the DSKPP server. and the DSKPP server.
Passphrase-Based Key Wrap This profile is a variation of the Key Passphrase-Based Key Wrap This profile is a variation of the Key
Wrap Profile. It is applicable to Wrap Profile. It is applicable to
constrained devices with keypads, e.g., constrained devices with keypads, e.g.,
mobile phones. Key wrap is carried out mobile phones. Key wrap is carried out
skipping to change at page 25, line 5 skipping to change at page 24, line 19
advance by both the cryptographic module advance by both the cryptographic module
and the DSKPP server. and the DSKPP server.
Passphrase-Based Key Wrap This profile is a variation of the Key Passphrase-Based Key Wrap This profile is a variation of the Key
Wrap Profile. It is applicable to Wrap Profile. It is applicable to
constrained devices with keypads, e.g., constrained devices with keypads, e.g.,
mobile phones. Key wrap is carried out mobile phones. Key wrap is carried out
using a passphrase-derived key-wrapping using a passphrase-derived key-wrapping
key, K_DERIVED, which is known in advance key, K_DERIVED, which is known in advance
by both the cryptographic module and by both the cryptographic module and
DSKPP server. DSKPP server.
This section describes the message flow and methods that comprise the
two-pass protocol variant.
The full 2-pass protocol exchange when the key is transported using 3.2.1. Message Flow
the client public key is as follows:
[<Trigger>]: The two-pass protocol flow consists of one exchange:
[ID_Device], [ID_K], [URL_S],[R_S] 1: Pass 1 = <KeyProvClientHello>, Pass 2 = <KeyProvServerFinished>
<KeyProvClientHello>: The client's initial <KeyProvClientHello> message is directly
followed by a <KeyProvServerFinished> message (unlike the four-pass
variant, there is no exchange of the <KeyProvServerHello> and
<KeyProvClientNonce> messages). However, as the two-pass variation
of DSKPP consists of one round trip to the server, the client is
still able to include its random nonce, R_C, algorithm preferences
and supported key types in the <KeyProvClientHello> message. Note
that by including R_C in <KeyProvClientHello>, the DSKPP client is
able to ensure the server is alive before "committing" the key.
[ID_Device], ID_K, R_S, R_C, AUTHDATA, Alg_List To ensure that a generated key K_TOKEN ends up associated with the
correct cryptographic module and user, the DSKPP server MAY couple an
initial user authentication to the DSKPP execution using one of the
mechanisms described in Section 3.3. Whatever the mechanism, the
DSKPP server MUST ensure that a generated key is associated with the
correct cryptographic module, and if applicable, the correct user.
<KeyProvServerFinished>: The purpose and content of each message are described below,
including the optional <KeyProvTrigger>.
ENC_K_CLIENT ( K_TOKEN || K_MAC)), K_CONFDATA, ID_S, DSKPP- DSKPP Client DSKPP Server
PRF_K_MAC("MAC 1 Computation" || ID_S || R_C, len(R_C) ), [ DSKPP- ------------ ------------
PRF_K_MAC'("MAC 1 Computation" || ID_S || R_C), 16] [<---] R_TRIGGER, [DeviceID],
[KeyID], [URL_S]
The full 2-pass protocol exchange when the key is wrapped using a The DSKPP server optionally sends a <KeyProvTrigger> message to the
shared key is as follows: DSKPP client. The trigger message MUST contain a nonce, R_TRIGGER,
to allow the server to couple the trigger with a later
<KeyProvClientHello> request. <KeyProvTrigger> MAY include DeviceID
to allow the client to select the device with which it will
communicate. In the case of key renewal, <KeyProvTrigger> SHOULD
include the identifier for the key, KeyID, that is being replaced.
Finally, the trigger MAY contain a URL for the DSKP client to use
when contacting the DSKPP server.
[<Trigger>]: DSKPP Client DSKPP Server
------------ ------------
R_C, SAL, KPML, [AD],
[R_TRIGGER],
[DeviceID], [KeyID] --->
[ID_Device], [ID_K], [URL_S],[R_S] The DSKPP client sends a <KeyProvClientHello> message to the DSKPP
server. <KeyProvClientHello> MUST include client nonce, R_C, and a
Security Attribute List (SAL), identifying which DSKPP versions,
protocol variations (in this case "two-pass"), key container formats,
key types, encryption and MAC algorithms that the client supports.
Unlike 4-pass DSKPP, the 2-pass DSKPP client uses the
<KeyProvClientHello> message to declare the list of Key Protection
Methods (KPML) it supports, providing required payload information in
accordance with Section 3.2.2. Optionally, the message MAY include
client Authentication Data (AD), such as a MAC derived from an
authentication code and R_C (refer to Section 3.3.2). In addition,
if a trigger message preceded <KeyProvClientHello>, then it passes
the parameters received in <KeyProvTrigger> back to the DSKPP Server.
In particular, it MUST include R_TRIGGER so that the DSKPP server can
associate the client with the trigger message, and SHOULD include
DeviceID and KeyID.
<KeyProvClientHello>: DSKPP Client DSKPP Server
------------ ------------
<--- KCH, KC, E(K,K_PROV),
MAC, AD
[ID_Device], ID_K, R_S, R_C, AUTHDATA, Alg_List If Authentication Data (AD) was received, then the DSKPP server MUST
authenticate the user in accordance with Section 3.3.2. If
authentication fails, then DSKPP server MUST abort. Otherwise, the
DSKPP server generates a key K_PROV from which two keys, K_TOKEN and
K_MAC, are derived. (Alternatively, the key K_PROV may have been
pre-generated as described in Section 1.1.1. The DSKPP server
selects a Key Protection Method (KPM) and applies it to K_PROV in
accordance with Section 3.2.2. The server then associates K_TOKEN
with the cryptographic module in a server-side data store. The
intent is that the data store later will be used by some service that
needs to verify or decrypt data produced by the cryptographic module
and the key.
<KeyProvServerFinished>: Once the association has been made, the DSKPP server sends a
confirmation message to the DSKPP client called
<KeyProvServerFinished>. For two-pass DSKPP, the confirmation
message MUST include a Key Container Header (KCH) that contains the
DSKPP Server's ID and KPM. The ServerID is used for authentication
purposes, and the KPM informs the DSKPP client of the security
context in which it will operate. In addition to the KCH, the
confirmation message MUST include the Key Container (KC) that holds
the KeyID, K_PROV from which K_TOKEN and K_MAC are derived, and
additional configuration information. The default symmetric key
container format is based on the Portable Symmetric Key Container
(PSKC) defined in [PSKC]. Alternative formats MAY include PKCS#12
[PKCS-12] or PKCS#5 XML [PKCS-5-XML]. Finally, <ServerFinished> MUST
include two MACs (MAC and AD) whose values are calculated with
contribution from the client nonce, R_C, provided in the
<ClientHello> message. The MAC values will allow the cryptographic
module to perform key confirmation and server authentication before
"commiting" the key (see Section 3.2.3 for more information).
ENC_K_SHARED(K_TOKEN || K_MAC), K_CONFDATA, ID_S, DSKPP- After receiving a <KeyProvServerFinished> message with Status =
PRF_K_MAC("MAC 1 Computation" || ID_S || R_C), [ DSKPP- "Success", the DSKPP client MUST verify both MAC values (MAC and AD).
PRF_K_MAC'("MAC 1 Computation "|| ID_S||R_C)] The DSKPP client MUST terminate the DSKPP session if either MAC does
not verify, and MUST, in this case, also delete any nonces, keys,
and/or secrets associated with the failed run of the protocol. If
<KeyProvServerFinished> has Status = "Success" and the MACs were
verified, then the DSKPP client MUST extract the key data from the
provided key container, and store data locally. After this
operation, it MUST NOT be possible to overwrite the key unless
knowledge of an authorizing key is proven through a MAC on a later
<KeyProvServerFinished> message.
The full 2-pass protocol when the key is wrapped using a passphrase 3.2.2. Key Protection Profiles
based derived key is as follows:
[<Trigger>]: This section introduces three profiles of two-pass DSKPP for key
protection. Further profiles MAY be defined by external entities or
through the IETF process.
[ID_Device], [ID_K], [URL_S],[R_S] 3.2.2.1. Key Transport Profile
<KeyProvClientHello>: This profile initializes the cryptographic module with a symmetric
key, K_TOKEN, through key transport and key derivation. The key
transport is carried out using a public key, K_CLIENT, whose private
key part resides in the cryptographic module as the transport key. A
key K_PROV from which two keys, K_TOKEN and K_MAC are derived MUST be
transported.
[ID_Device], ID_K, R_S, R_C, AUTHDATA, Alg_List This profile MUST be identified with the following URN:
urn:ietf:params:xml:schema:keyprov:protocol#transport
<KeyProvServerFinished>: In the two-pass version of DSKPP, the client MUST send a payload
associated with this key protection method. The payload MUST be of
type ds:KeyInfoType ([XMLDSIG]), and only those choices of the ds:
KeyInfoType that identify a public key are allowed. The ds:
X509Certificate option of the ds:X509Data alternative is RECOMMENDED
when the public key corresponding to the private key on the
cryptographic module has been certified.
ENC_K_DERIVED(K_TOKEN || K_MAC), K_CONFDATA, ID_S, DSKPP- The server payload associated with this key protection method MUST be
PRF_K_MAC("MAC 1 Computation" || ID_S || R_C), [ DSKPP- of type xenc:EncryptedKeyType ([XMLENC]), and only those encryption
PRF_K_MAC'("MAC 1 Computation" || ID_S || R_C)] methods utilizing a public key that are supported by the DSKPP client
(as indicated in the <SupportedEncryptionAlgorithms> element of the
<KeyProvClientHello> message in the case of 2-pass DSKPP) are allowed
as values for the <xenc:EncryptionMethod> element. Further, in the
case of 2-pass DSKPP, the <ds:KeyInfo> element MUST contain the same
value (i.e. identify the same public key) as the <Payload> of the
corresponding supported key protection method in the
<KeyProvClientHello> message that triggered the response. The
<CarriedKeyName> element MAY be present, but MUST, when present,
contain the same value as the <KeyID> element of the
<KeyProvServerFinished> message. The Type attribute of the xenc:
EncryptedKeyType MUST be present and MUST identify the type of the
wrapped key. The type MUST be one of the types supported by the
DSKPP client (as reported in the <SupportedKeyTypes> of the preceding
<KeyProvClientHello> message in the case of 2-pass DSKPP). The
transported key MUST consist of two parts of equal length. The first
half constitutes K_MAC and the second half constitutes K_TOKEN. The
length of K_TOKEN (and hence also the length of K_MAC) is determined
by the type of K_TOKEN.
The following subsections describe these exchanges in more detail. DSKPP servers and cryptographic modules supporting this profile MUST
support the http://www.w3.org/2001/04/xmlenc#rsa-1_5 key-wrapping
mechanism defined in [XMLENC].
4.4.1. Message Flow When this profile is used, the MacAlgorithm attribute of the <Mac>
element of the <KeyProvServerFinished> message MUST be present and
MUST identify the selected MAC algorithm. The selected MAC algorithm
MUST be one of the MAC algorithms supported by the DSKPP client (as
indicated in the <SupportedMacAlgorithms> element of the
<KeyProvClientHello> message in the case of 2-pass DSKPP). The MAC
MUST be calculated as described in Section 3.2 for Two-Pass DSKPP.
The 2-pass protocol flow consists of one round trip between the DSKPP In addition, DSKPP servers MUST include the AuthenticationDataType
client and DSKPP server, which consists of two "passes", i.e., one element in their <KeyProvServerFinished> messages whenever a
request message and one response message: successful protocol run will result in an existing K_TOKEN being
replaced.
Round-trip #1: Pass 1=<KeyProvClientHello>, Pass 3.2.2.2. Key Wrap Profile
2=<KeyProvServerFinished>
a. The DSKPP client sends a <KeyProvClientHello> message to the This profile initializes the cryptographic module with a symmetric
DSKPP server. The message provides the client nonce, R_C, and key, K_TOKEN, through key wrap and key derivation. The key wrap MUST
information about the DSKPP versions, protocol variants, key be carried out using a (symmetric) key-wrapping key, K_SHARED, known
types, encryption and MAC algorithms supported by the in advance by both the cryptographic module and the DSKPP server. A
cryptographic module for the purposes of this protocol. The key K_PROV from which two keys, K_TOKEN and K_MAC are derived MUST be
message may also include client authentication data, such as wrapped.
device certificate or MAC derived from authentication code and
R_C. Authentication code is sent in clear only when underlying
transport layer can ensure data confidentiality. Unlike 4-pass
DSKPP, 2-pass DSKPP client uses the <KeyProvClientHello> message
to declare which key initialization method it supports, providing
required payload information, e.g., K_CLIENT for the Key
Transport Profile.
b. The DSKPP server generates a key K from which two keys, K_TOKEN
and K_MAC are derived. (Alternatively, the key K may have been
pre-generated as described in Section 3.1. K is either
transported or wrapped in accordance with the key initialization
method specified by the DSKPP client in the <KeyProvClientHello>
message. The server then associates K_TOKEN with the
cryptographic module in a server-side data store. The intent is
that the data store later on will be used by some service that
needs to verify or decrypt data produced by the cryptographic
module and the key.
c. Once the association has been made, the DSKPP server sends a
confirmation message to the DSKPP client called
<KeyProvServerFinished>. The confirmation message includes a key
container that holds an identifier for the key, the key K from
which K_TOKEN and K_MAC are derived, and additional configuration
information (note that the latter MUST include the identity of
the DSKPP server for authentication purposes). In addition,
<KeyProvServerFinished> MUST include two MACs whose values are
calculated with contribution from the client nonce, R_C, provided
in the <KeyProvClientHello> message. The data will allow the
cryptographic module to perform key confirmation and server
authentication before "committing" the key. Note that the second
MAC value that is intended for key confirmation MAY only be used
for replacing and existing key.
d. Upon receipt of the DSKPP server's confirmation message, the
cryptographic module extracts the key data from the provided key
container, uses the provided MAC values to perform key
confirmation and server authentication, and stores the key
material locally.
4.4.2. Key Confirmation This profile MUST be identified with the following URI:
urn:ietf:params:xml:schema:keyprov:protocol#wrap
In two-pass DSKPP, the client is REQUIRED to include a nonce R in the In the 2-pass version of DSKPP, the client MUST send a payload
<KeyProvClientHello> message. Further, the server is REQUIRED to associated with this key protection method. The payload MUST be of
include an identifier, ID_S, for itself (via the key container) in type ds:KeyInfoType ([XMLDSIG]), and only those choices of the ds:
the <KeyProvServerFinished> message. The MAC value in the KeyInfoType that identify a symmetric key are allowed. The ds:
<KeyProvServerFinished> message MUST be computed on the (ASCII) KeyName alternative is RECOMMENDED.
string "MAC 1 computation", the server identifier ID_S, and R using a
MAC key K_MAC. This key MUST be provided together with K_TOKEN to The server payload associated with this key protection method MUST be
the cryptographic module. of type xenc:EncryptedKeyType ([XMLENC]), and only those encryption
methods utilizing a symmetric key that are supported by the DSKPP
client (as indicated in the <SupportedEncryptionAlgorithms> element
of the <KeyProvClientHello> message in the case of 2-pass DSKPP) are
allowed as values for the <xenc:EncryptionMethod> element. Further,
in the case of 2-pass DSKPP, the <ds:KeyInfo> element MUST contain
the same value (i.e. identify the same symmetric key) as the
<Payload> of the corresponding supported key protection method in the
<KeyProvClientHello> message that triggered the response. The
<CarriedKeyName> element MAY be present, and MUST, when present,
contain the same value as the <KeyID> element of the
<KeyProvServerFinished> message. The Type attribute of the xenc:
EncryptedKeyType MUST be present and MUST identify the type of the
wrapped key. The type MUST be one of the types supported by the
DSKPP client (as reported in the <SupportedKeyTypes> of the preceding
<KeyProvClientHello> message in the case of 2-pass DSKPP). The
wrapped key MUST consist of two parts of equal length. The first
half constitutes K_MAC and the second half constitutes K_TOKEN. The
length of K_TOKEN (and hence also the length of K_MAC) is determined
by the type of K_TOKEN.
DSKPP servers and cryptographic modules supporting this profile MUST
support the http://www.w3.org/2001/04/xmlenc#kw-aes128 key-wrapping
mechanism defined in [XMLENC].
When this profile is used, the MacAlgorithm attribute of the <Mac>
element of the <KeyProvServerFinished> message MUST be present and
MUST identify the selected MAC algorithm. The selected MAC algorithm
MUST be one of the MAC algorithms supported by the DSKPP client (as
indicated in the <SupportedMacAlgorithms> element of the
<KeyProvClientHello> message in the case of 2-pass DSKPP). The MAC
MUST be calculated as described in Section 3.2.
In addition, DSKPP servers MUST include the AuthenticationDataType
element in their <KeyProvServerFinished> messages whenever a
successful protocol run will result in an existing K_TOKEN being
replaced.
3.2.2.3. Passphrase-Based Key Wrap Profile
This profile is a variation of the key wrap profile. It initializes
the cryptographic module with a symmetric key, K_TOKEN, through key
wrap and key derivation, using a passphrase-derived key-wrapping key,
K_DERIVED. The passphrase is known in advance by both the device
user and the DSKPP server. To preserve the property of not exposing
K_TOKEN to any other entity than the DSKPP server and the
cryptographic module itself, the method SHOULD be employed only when
the device contains facilities (e.g. a keypad) for direct entry of
the passphrase. A key K_PROV from which two keys, K_TOKEN and K_MAC
are derived MUST be wrapped.
This profile MUST be identified with the following URI:
urn:ietf:params:xml:schema:keyprov:protocol#passphrase-wrap
In the 2-pass version of DSKPP, the client MUST send a payload
associated with this key protection method. The payload MUST be of
type ds:KeyInfoType ([XMLDSIG]). The ds:KeyName option MUST be used
and the key name MUST identify the passphrase that will be used by
the server to generate the key-wrapping key. As an example, the
identifier could be a user identifier or a registration identifier
issued by the server to the user during a session preceding the DSKPP
protocol run.
The server payload associated with this key protection method MUST be
of type xenc:EncryptedKeyType ([XMLENC]), and only those encryption
methods utilizing a passphrase to derive the key-wrapping key that
are supported by the DSKPP client (as indicated in the
<SupportedEncryptionAlgorithms> element of the <KeyProvClientHello>
message in the case of 2-pass DSKPP) are allowed as values for the
<xenc:EncryptionMethod> element. Further, in the case of 2-pass
DSKPP, the <ds:KeyInfo> element MUST contain the same value (i.e.
identify the same passphrase) as the <Payload> of the corresponding
supported key protection method in the <KeyProvClientHello> message
that triggered the response. The <CarriedKeyName> element MAY be
present, and MUST, when present, contain the same value as the
<KeyID> element of the <KeyProvServerFinished> message. The Type
attribute of the xenc:EncryptedKeyType MUST be present and MUST
identify the type of the wrapped key. The type MUST be one of the
types supported by the DSKPP client (as reported in the
<SupportedKeyTypes> of the preceding <KeyProvClientHello> message in
the case of 2-pass DSKPP). The wrapped key MUST consist of two parts
of equal length. The first half constitutes K_MAC and the second
half constitutes K_TOKEN. The length of K_TOKEN (and hence also the
length of K_MAC) is determined by the type of K_TOKEN.
DSKPP servers and cryptographic modules supporting this profile MUST
support the PBES2 password based encryption scheme defined in
[PKCS-5] (and identified as
http://www.rsasecurity.com/rsalabs/pkcs/schemas/pkcs-5#pbes2 in
[PKCS-5-XML]), the PBKDF2 passphrase-based key derivation function
also defined in [PKCS-5] (and identified as
http://www.rsasecurity.com/rsalabs/pkcs/schemas/pkcs-5#pbkdf2 in
[PKCS-5-XML]), and the http://www.w3.org/2001/04/xmlenc#kw-aes128
key-wrapping mechanism defined in [XMLENC].
When this profile is used, the MacAlgorithm attribute of the <Mac>
element of the <KeyProvServerFinished> message MUST be present and
MUST identify the selected MAC algorithm. The selected MAC algorithm
MUST be one of the MAC algorithms supported by the DSKPP client (as
indicated in the <SupportedMacAlgorithms> element of the
<KeyProvClientHello> message in the case of 2-pass DSKPP). The MAC
MUST be calculated as described in Section 3.2.
In addition, DSKPP servers MUST include the AuthenticationDataType
element in their <KeyProvServerFinished> messages whenever a
successful protocol run will result in an existing K_TOKEN being
replaced.
3.2.3. MAC Calculations
3.2.3.1. Key Confirmation
In two-pass DSKPP, the client MUST include a nonce R in the
<KeyProvClientHello> message. Further, the DSKPP server MUST include
its identifier, ServerID, in the <KeyProvServerFinished> message (via
the Key Container). The MAC value in the <KeyProvServerFinished>
message MUST be computed on the (ASCII) string "MAC 1 computation",
the server identifier ServerID, and R using a MAC key K_MAC. This
key MUST be provided together with K_TOKEN to the cryptographic
module.
If DSKPP-PRF is used as the MAC algorithm, then the input parameter s If DSKPP-PRF is used as the MAC algorithm, then the input parameter s
MUST consist of the concatenation of the (ASCII) string "MAC 1 MUST consist of the concatenation of the (ASCII) string "MAC 1
computation" and R, and the parameter dsLen MUST be set to the length computation" and R, and the parameter dsLen MUST be set to the length
of R: of R:
dsLen = len(R) dsLen = len(R)
MAC = DSKPP-PRF (K_MAC, "MAC 1 computation" || ID_S || R, dsLen) MAC = DSKPP-PRF (K_MAC, "MAC 1 computation" || ServerID || R, dsLen)
4.4.3. Server Authentication 3.2.3.2. Server Authorization
A server MUST authenticate itself when attempting to replace an A MAC MUST be present in the <KeyProvServerFinished> message as proof
existing K_TOKEN. In 2-pass DSKPP, servers authenticate themselves that the DSKPP server is authorized to provide a new key to the
by including a second MAC value in the AuthenticationDataType element cryptographic module. In 2-pass DSKPP, servers include this MAC
of <KeyProvServerFinished>. The MAC value in the value in the AuthenticationDataType element of
AuthenticationDataType element MUST be computed on the (ASCII) string <KeyProvServerFinished>. The MAC value in the AuthenticationDataType
"MAC 1 computation", the server identifier ID_S, and R, using the element MUST be computed on the (ASCII) string "MAC 1 computation",
existing MAC key K_MAC' (the MAC key that existed before this the server identifier ServerID, and R, using the existing MAC key
protocol run). The MAC algorithm MUST be the same as the algorithm K_MAC' (the MAC key that existed before this protocol run). The MAC
used for key confirmation purposes. algorithm MUST be the same as the algorithm used for key confirmation
purposes.
If DSKPP-PRF is used as the MAC algorithm, then the input parameter s If DSKPP-PRF is used as the MAC algorithm, then the input parameter s
MUST consist of the concatenation of the (ASCII) string "MAC 1 MUST consist of the concatenation of the (ASCII) string "MAC 1
computation" ID_S, and R. The parameter dsLen MUST be set to at least computation" ServerID, and R. The parameter dsLen MUST be set to at
16 (i.e. the length of the MAC MUST be at least 16 octets): least 16 (i.e. the length of the MAC MUST be at least 16 octets):
dsLen >= 16 dsLen >= 16
MAC = DSKPP-PRF (K_MAC', "MAC 1 computation" || ID_S || R, dsLen) MAC = DSKPP-PRF (K_MAC', "MAC 1 computation" || ServerID || R, dsLen)
4.5. One-Pass Protocol Usage 3.3. User Authentication
The one-pass protocol flow is suitable for environments wherein near The DSKPP server MUST ensure that a generated key is associated with
real-time communication between the DSKPP client and server may not the correct cryptographic module, and if applicable, the correct
be possible. It is also suitable for environments wherein user. If the user has not been authenticated by some out-of-band
administrative approval is a required step in the flow, and for means, then the user SHOULD be authenticated within the DSKPP. For a
provisioning of pre-generated keys. In one-pass DSKPP, the server further discussion of this, and threats related to man-in-the-middle
simply sends a <KeyProvServerFinished> message to the DSKPP client. attacks in this context, see Section 9.
In this case, there is no exchange of the <KeyProvClientHello>,
<KeyProvServerHello>, and <KeyProvClientNonce> DSKPP messages, and
hence there is no way for the client to express supported algorithms
or key types. Before attempting one-pass DSKPP, the server MUST
therefore have prior knowledge not only that the client is able and
willing to accept this variant of DSKPP, but also of algorithms and
key types supported by the client.
Essentially, one-pass DSKPP is a transport of key material from the When relying on DSKPP for user authentication, the DSKPP server
DSKPP server to the DSKPP client. As with two-pass DSKPP, the one- SHOULD explicitly:
pass variant relies on key initialization methods that ensure K_TOKEN
is not exposed to any other entity than the DSKPP server and the
cryptographic module itself. The same key initialization profiles
are defined as described in Section 4.4 and Section 11.
Outside the specific cases where one-pass DSKPP is desired, clients o Bind the user to the device (see Section 3.3.1, below)
SHOULD be constructed and configured to only accept DSKPP server
messages in response to client-initiated transactions.
The 1-pass protocol when the key is transported using the client o Rely on client-provided Authentication Data (AD) to verify that a
public Key is as follows: legitimate user is behind the wheel (see Section 3.3.2, below)
<KeyProvServerFinished>: NOTE: Device authentication can be handled implicitly by either
relying on the device certificate for wrapping the key in the two-
pass DSKPP Key Wrap Profile (seeSection 3.2.2), or by coupling the
device certificate with the Authentication Code (see below).
ENC_K_CLIENT ( K_TOKEN || K_MAC)), K_CONFDATA, DSKPP-PRF_K_MAC 3.3.1. Device Identifier
("MAC 1 Computation" || ID_S || I), [ DSKPP-PRF_K_MAC'("MAC 2
Computation"||ID_S||I')]
The 1-pass protocol when the key is wrapped using a shared key is as The DSKPP server MAY be pre-configured with a unique device
follows: identifier corresponding to a particular cryptographic module. The
DSKPP server MAY then include this identifier in the DSKPP
initialization trigger, in which case the DSKPP client MUST include
it in its message(s) to the DSKPP server for authentication. Note
that it is also legitimate for a DSKPP client to initiate the DSKPP
protocol run without having received an initialization message from a
server, but in this case any provided device identifier MUST NOT be
accepted by the DSKPP server unless the server has access to a unique
key for the identified device and that key will be used in the
protocol.
<KeyProvServerFinished>: 3.3.2. Authentication Data
ENC_K_SHARED (K_TOKEN || K_MAC), K_CONFDATA, DSKPP-PRF_K_MAC("MAC As described in the message flows above (see Section 3.1.1 and
1 Computation" || ID_S || I), [ PRF_K_MAC'("MAC 2 Computation" || Section 3.2.1), the DSKPP client MAY include Authentication Data (AD)
ID_S || I')] in its request(s). Note that AD MAY be omitted if client certificate
authentication has been provided by the transport channel such as
TLS. Nonetheless, when AD is provided, the DSKPP server MUST verify
the data before continuing with the protocol run. The DSKPP client
generates AD through derivation of an Authentication Code (AC) as
follows (see Section 3.3.2.2 for details):
The 1-pass protocol when the key is wrapped using a passphrase AD = HMAC(AC, K)
derived key is as follows:
<KeyProvServerFinished>: AC is a one-time use value that is a special form of a shared secret
between a user and the DSKPP server. This secret MUST be made
available to the client before or during DSKPP initiation. Two ways
in which this MAY be done are:
ENC_K_DERIVED(K_TOKEN || K_MAC), K_CONFDATA, DSKPP-PRF_K_MAC("MAC a. A key issuer may deliver an AC to the user or device in response
1 Computation" || ID_S || I), [DSKPP-PRF_K_MAC'("MAC 2 to a key request, which the user enters into an application
Computation" || ID_S || I')] hosted on their device. For example, a user runs an application
that is resident on their device, e.g., a mobile phone. The
application cannot proceed without a new symmetric key. The user
is redirected to an issuer's Web site from where the user
requests a key. The issuer's Web application processes the
request, and returns an AC, which then appears on the user's
display. The user then invokes a symmetric key-based application
hosted on the device, which asks the user to input the AC using a
keypad. The application invokes the DSKPP client, providing it
with the AC.
The subsections below describe the 1-pass protocol in more detail. b. The provisioning server may send a trigger message,
<KeyProvTrigger>, to the DSKPP client, which and set the value of
the trigger nonce, R_TRIGGER, to AC. When this method is used, a
transport providing privacy and integrity MUST be used to deliver
the DSKPP initialization trigger from the DSKPP server to the
DSKPP client, e.g. HTTPS.
4.5.1. Message Flow Note that when an issuer delegates symmetric key provisioning to a
third party provisioning service provider, both client authentication
and issuer authentication are required by the provisioning server.
Client authentication to the issuer MAY be in-band or out-of-band as
described above. The issuer acts as a proxy for the provisioning
server. The issuer authenticates to the provisioning service
provider either using a certificate or a pre-established secret key.
The 1-pass protocol flow consists of one "pass", i.e., a single A description of the AC and how it is used to derive AD is contained
message sent from the DSKPP server to the DSKPP client: in the sub-sections below.
Pass 1: <KeyProvServerFinished> 3.3.2.1. Authentication Code Format
a. The DSKPP server generates a key K from which two keys, K_TOKEN At a minimum, the AC MUST contain the following parameters:
and K_MAC are derived. K is either transported or wrapped in
accordance with the key initialization method known in advance by
the DSKPP server. The server then associates K_TOKEN with the
cryptographic module in a server-side data store. The intent is
that the data store later on will be used by some service that
needs to verify or decrypt data produced by the cryptographic
module and the key.
b. Once the association has been made, the DSKPP server sends a
confirmation message to the DSKPP client called
<KeyProvServerFinished>. The confirmation message includes a key
container that holds an identifier for the key, the key K from
which K_TOKEN and K_MAC are derived, and additional configuration
information (note that the latter MUST include the identity of
the DSKPP server for authentication purposes). In addition,
<KeyProvServerFinished> MUST include two MACs, which will allow
the cryptographic module to perform key confirmation and server
authentication before "commuting" the key. Note that unlike two-
pass DSKPP, in the one-pass variant, the server does not have the
client nonce, R_C, and therefore the MACs values are calculated
with contribution from an unsigned integer, I, generated by the
server during the protocol run.
c. Upon receipt of the DSKPP server's confirmation message, the identifier: A globally unique identifier that represents the user's
cryptographic module extracts the key data from the provided key key request. The MAY be generated as a sequence number.
container, uses the two MAC values to perform key confirmation
and server authentication, and stores the key material locally.
4.5.2. Key Confirmation password: A unique value that SHOULD be generated by the system as a
random number to make AC more difficult to guess.
In one-pass DSKPP, the server MUST include an identifier, ID_S, for checksum: The checksum SHOULD be calculated from the remaining
itself (via the key container) in the <KeyProvServerFinished> digits in the AC.
message. The MAC value in the <KeyProvServerFinished> message MUST
be computed on the (ASCII) string "MAC 1 computation", the server
identifier ID_S, and an unsigned integer value I, using a MAC key
K_MAC. The value I MUST be monotonically increasing and guaranteed
not to be used again by this server towards this cryptographic
module. It could for example be the number of seconds since some
point in time with sufficient granularity, a counter value, or a
combination of the two where the counter value is reset for each new
time value. In contrast to the MAC calculation in four-pass DSKPP,
the MAC key K_MAC MUST be provided together with K_TOKEN to the
cryptographic module.
Note: The integer I does not necessarily need to be maintained by the The Issuer MUST rely on a Tag-Length-Value (TLV) format to represent
DSKPP server on a per cryptographic module basis (it is enough if the the AC, such as:
server can guarantee that the same value is never being sent twice to
the same cryptographic module).
If DSKPP-PRF is used as the MAC algorithm, then the input parameter s Tag = 0x01 = password
MUST consist of the concatenation of the (ASCII) string "MAC 1 Tag = 0x02 = identifier
computation", ID_S, and I. The parameter dsLen MUST be set to at Tag = 0x03 = checksum
least 16 (i.e. the length of the MAC MUST be at least 16 octets):
dsLen >= 16 where one (or two) byte(s) MAY be used to indicate the L(ength) of
the V(alue) field.
MAC = DSKPP-PRF (K_MAC, "MAC 1 computation" || ID_S || I, dsLen) 3.3.2.2. MAC Calculation
The server MUST provide I to the client in the Nonce attribute of the The Authentication Data is a MAC that is derived from AC as follows
<Mac> element of the <KeyProvServerFinished> message using the (refer to Section 3.4 for a description of DSKPP-PRF in general and
AuthenticationCodeMacType defined in Section 6.2.2.4. Appendix C for a description of DSKPP-PRF-AES):
4.5.3. Server Authentication MAC = DSKPP-PRF-AES(K_AC, AC->Identifier||URL_S||R_C||[R_S], 16)
As discussed in , servers need to authenticate themselves when In four-pass DSKPP, the cryptographic module uses R_C, R_S, and
attempting to replace an existing K_TOKEN. In 1-pass DSKPP, servers URL_S, to calculate the MAC. In two-pass DSKPP, the cryptographic
authenticate themselves by including a second MAC value in the module does not have access to R_S, therefore only R_C is used in
AuthenticationDataType element of <KeyProvServerFinished>. The MAC combination with URL_S to produce the MAC. In either case, K_AC MAY
value in the AuthenticationDataType element MUST be computed on the be derived from AC>password as follows [PKCS-5]:
(ASCII) string "MAC 1 computation", the server identifier ID_S, and a
new value I', I' > I, using the existing MAC key K_MAC' (the MAC key
that existed before this protocol run). The MAC algorithm MUST be
the same as the algorithm used for key confirmation purposes.
If DSKPP-PRF is used as the MAC algorithm, then the input parameter s K_AC = PBKDF2(AC->password, R_C || [K], c, 16)
MUST consist of the concatenation of the (ASCII) string "MAC 1
computation" ID_S, and I'. The parameter dsLen MUST be set to at
least 16 (i.e. the length of the MAC MUST be at least 16 octets):
dsLen >= 16 K MAY be one of the following:
MAC = DSKPP-PRF (K_MAC', "MAC 1 computation" || ID_S || I', dsLen) K_CLIENT: The device public key when a device certificate is
available and used for key transport in 2-pass
The server MUST provide I' to the client in the Nonce attribute of K_SHARED: The shared key between the client and the server when it
the <Mac> element of the AuthenticationDataType extension. If the is used for key wrap in two-pass or for R_C protection in four-
protocol run is successful, the client stores I' as the new value of pass
I for this server.
5. Methods Common to More Than One Protocol Variant K_DERIVED: When a passphrase-derived key is used for key wrap in
two-pass DSKPP.
The mechanisms contained in this section are used in more than one Finally, c is iteration count between 10 and 1000.
variant of DSKPP.
5.1. The DSKPP One-Way Pseudorandom Function, DSKPP-PRF 3.4. The DSKPP One-Way Pseudorandom Function, DSKPP-PRF
5.1.1. Introduction 3.4.1. Introduction
All of the protocol variants depend on DSKPP-PRF. The general All of the protocol variations depend on DSKPP-PRF. The general
requirements on DSKPP-PRF are the same as on keyed hash functions: It requirements on DSKPP-PRF are the same as on keyed hash functions: It
MUST take an arbitrary length input, and be one-way and collision- MUST take an arbitrary length input, and be one-way and collision-
free (for a definition of these terms, see, e.g., [FAQ]). Further, free (for a definition of these terms, see, e.g., [FAQ]). Further,
the DSKPP-PRF function MUST be capable of generating a variable- the DSKPP-PRF function MUST be capable of generating a variable-
length output, and its output MUST be unpredictable even if other length output, and its output MUST be unpredictable even if other
outputs for the same key are known. outputs for the same key are known.
It is assumed that any realization of DSKPP-PRF takes three input It is assumed that any realization of DSKPP-PRF takes three input
parameters: A secret key k, some combination of variable data, and parameters: A secret key k, some combination of variable data, and
the desired length of the output. The combination of variable data the desired length of the output. The combination of variable data
can, without loss of generalization, be considered as a salt value can, without loss of generalization, be considered as a salt value
(see PKCS#5 Version 2.0 [PKCS-5], Section 4), and this (see PKCS#5 Version 2.0 [PKCS-5], Section 4), and this
characterization of DSKPP-PRF SHOULD fit all actual PRF algorithms characterization of DSKPP-PRF SHOULD fit all actual PRF algorithms
implemented by cryptographic modules. From the point of view of this implemented by cryptographic modules. From the point of view of this
specification, DSKPP-PRF is a "black-box" function that, given the specification, DSKPP-PRF is a "black-box" function that, given the
inputs, generates a pseudorandom value. inputs, generates a pseudorandom value.
Separate specifications MAY define the implementation of DSKPP-PRF Separate specifications MAY define the implementation of DSKPP-PRF
for various types of cryptographic modules. Appendix B contains two for various types of cryptographic modules. Appendix C contains two
example realizations of DSKPP-PRF. example realizations of DSKPP-PRF.
5.1.2. Declaration 3.4.2. Declaration
DSKPP-PRF (k, s, dsLen) DSKPP-PRF (k, s, dsLen)
Input: Input:
k secret key in octet string format k secret key in octet string format
s octet string of varying length consisting of variable data s octet string of varying length consisting of variable data
distinguishing the particular string being derived distinguishing the particular string being derived
dsLen desired length of the output dsLen desired length of the output
Output: Output:
DS pseudorandom string, dsLen-octets long DS pseudorandom string, dsLen-octets long
For the purposes of this document, the secret key k MUST be at least For the purposes of this document, the secret key k MUST be at least
16 octets long. 16 octets long.
5.2. Encryption of Pseudorandom Nonces Sent from the DSKPP Client 3.5. Encryption of Pseudorandom Nonces Sent from the DSKPP Client
(Applicable to Four-Pass and Two-Pass DSKPP)
During 4- and 2-pass message exchanges, DSKPP client random nonce(s) DSKPP client random nonce(s) are either encrypted with the public key
are either encrypted with the public key provided by the DSKPP server provided by the DSKPP server or by a shared secret key. For example,
or by a shared secret key. For example, in the case of a public RSA in the case of a public RSA key, an RSA encryption scheme from PKCS
key, an RSA encryption scheme from PKCS #1 [PKCS-1] MAY be used. #1 [PKCS-1] MAY be used.
In the case of a shared secret key, to avoid dependence on other In the case of a shared secret key, to avoid dependence on other
algorithms, the DSKPP client MAY use the DSKPP-PRF function described algorithms, the DSKPP client MAY use the DSKPP-PRF function described
herein with the shared secret key K_SHARED as input parameter k (in herein with the shared secret key K_SHARED as input parameter K (in
this case, K_SHARED SHOULD be used solely for this purpose), the this case, K_SHARED SHOULD be used solely for this purpose), the
concatenation of the (ASCII) string "Encryption" and the server's concatenation of the (ASCII) string "Encryption" and the server's
nonce R_S as input parameter s, and dsLen set to the length of R_C: nonce R_S as input parameter s, and dsLen set to the length of R_C:
dsLen = len(R_C) dsLen = len(R_C)
DS = DSKPP-PRF(K_SHARED, "Encryption" || R_S, dsLen) DS = DSKPP-PRF(K_SHARED, "Encryption" || R_S, dsLen)
This will produce a pseudorandom string DS of length equal to R_C. This will produce a pseudorandom string DS of length equal to R_C.
Encryption of R_C MAY then be achieved by XOR-ing DS with R_C: Encryption of R_C MAY then be achieved by XOR-ing DS with R_C:
Enc-R_C = DS ^ R_C E(DS, R_C) = DS ^ R_C
The DSKPP server will then perform the reverse operation to extract The DSKPP server will then perform the reverse operation to extract
R_C from Enc-R_C. R_C from E(DS, R_C).
5.3. Client Authentication Mechanisms (Applicable to Four- and Two-Pass
DSKPP)
To ensure that a generated K_TOKEN ends up associated with the
correct cryptographic module and user, the DSKPP server MAY couple an
initial user authentication to the DSKPP execution in several ways,
as discussed in the following sub-sections. Whatever the method, the
DSKPP server MUST ensure that a generated key is associated with the
correct cryptographic module, and if applicable, the correct user.
For a further discussion of this, and threats related to man-in-the-
middle attacks in this context, see Section 14.
5.3.1. Device Certificate
Instead of requiring an Authentication Code for in-band
authentication, a device private key and certificate could be used,
which was supplied with the cryptographic module by its issuer for
client authentication at the transport layer e.g TLS/HTTPS. When the
Device certificate is available and client authentication is not
provided in the transport layer, the DSKPP client may include a
device's certificate signed data for the authentication data.
5.3.2. Device Identifier
The DSKPP server could be pre-configured with a unique device
identifier corresponding to a particular cryptographic module. The
DSKPP server MAY then include this identifier in the DSKPP
initialization trigger, and the DSKPP client would include it in its
message(s) to the DSKPP server for authentication. Note that it is
also legitimate for a DSKPP client to initiate the DSKPP protocol run
without having received an initialization message from a server, but
in this case any provided device identifier MUST NOT be accepted by
the DSKPP server unless the server has access to a unique key for the
identified device and that key will be used in the protocol.
5.3.3. Authentication Code
As shown in Figure 5, a key issuer may provide a one-time value,
called an Authentication Code, to the user or device out-of-band and
require this value to be used by the DSKPP client when contacting the
DSKPP server. The DSKPP client MAY include the authentication data
in its <KeyProvClientHello> (and <KeyProvClientNonce> for four-pass)
message, and the DSKPP server MUST verify the data before continuing
with the protocol run.
Note: An alternate method for getting the Authentication Code to the
client, is for the DSKPP server to place the value in the
<TriggerNonce> element of the DSKPP initialization trigger (if
triggers are used; see Section 12.2.7) . When this method is used, a
transport providing privacy and integrity MUST be used to deliver the
DSKPP initialization trigger from the DSKPP server to the DSKPP
client, e.g. HTTPS.
+------------+ Get Authentication Code +------------+
| User |<------------------------->| Issuer |
+------------+ +------------+
| |
| |
| |
V V
+--------------+ +--------------+
| DSKPP | Authentication Data | DSKPP |
| Client |----------------------->| Server |
+--------------+ +--------------+
Figure 5: User Authentication with One-Time Code
The Authentication Code, AUTHCODE, may be considered as a special
form of a shared secret between a User and a DSKPP server. The
Issuer may generate the Authentication Code as follows:
AUTHCODE = passwordLen || identifier || password || checksum
where
passwordLen : 1 digit indicating the 'password' length. The maximum
length of the password is 10. A passwordLen value '0'
indicates a password of 10 digits.
identifier : A globally unique identifier of the user's order for
token provisioning. The length of the identifier may be
fixed e.g. 10 digits or variable e.g. 1 to 20 digits. The
identifier may be generated as a sequence number.
password : 6 to 10 digits. The password should be generated by the
system as a random number to make the AUTHCODE more
difficult to guess.
checksum : 1 digit calculated from the remaining digits in the code.
The Authentication Data, AUTHDATA, may be derived from the AUTHCODE
and other information as follows:
MAC = DSKPP-PRF-AES(K_AUTHCODE, AUTHCODE->Identifier || URL_S ||
[R_S], 16)
where
Refer to Section 5.1 for a description of DSKPP-PRF in general and
Appendix B for a description of DSKPP-PRF-AES.
In four-pass DSKPP, the cryptographic module uses the client nonce
R_C, the server nonce R_S, and the server URL URL_S to calculate
the MAC. In two-pass DSKPP, the cryptographic module does not
have access to the server nonce R_S therefore only the client
nonce R_C is used in combination with the server URL URL_S to
produce the MAC.
The K_AUTHCODE MAY be derived from AUTHCODE>password as follows:
K_AUTHCODE = truncate( Hash( Hash(...n times...(
AUTHCODE->password ||R_C||[K]) ) ) )
where
K is optional and MAY be one of the following:
K_CLIENT: The device public key when a device
certificate is available and used for key transport
in 2-pass
K_SHARED: The shared key between the Client and the
Server when it is used for key wrap in two-pass or
for R_C protection in four-pass
K_DERIVED: when a passphrase derived key is used for
key wrap in two-pass.
'truncate()' returns the first 16 bytes from the result of the
last hash iteration, and n is the number of hash iterations. n
may be any number between 10 and 1000.
Notes:
1 Authentication data MAY be omitted if client certificate
authentication has been provided by the transport channel such as
TLS.
2 When an issuer delegates symmetric key provisioning to a third
party provisioning service provider, both client authentication
and issuer authentication are required by the provisioning server.
Client authentication to the issuer MAY be in-band or out-of-band
as described above. The issuer acts as a proxy for the
provisioning server. The issuer authenticates to the provisioning
service provider either using a certificate or a pre-established
secret key.
5.4. Client Authentication Examples
5.4.1. Example Using a MAC from an Authentication Code
<AuthenticationData>
<ClientID>31300257</ClientID>
<AuthenticationCodeMac>
<IterationCount>512</IterationCount>
<Mac>4bRJf9xXd3KchKoTenHJiw==</Mac>
</AuthenticationCodeMac>
</AuthenticationData>
5.4.2. Example Using a Device Certificate
<AuthenticationData>
<DigitalSignature>
<ds:SignedInfo>
<ds:CanonicalizationMethod
Algorithm="http://www.w3.org/TR/2001/REC-xml-c14n-20010315" />
<ds:SignatureMethod Algorithm="http://www.w3.org/2000/09/xmldsig#rsa-sha1"/>
<ds:Reference URI="#Nonce">
<ds:DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#sha1"/>
<ds:DigestValue></ds:DigestValue>
</ds:Reference>
</ds:SignedInfo>
<ds:SignatureValue></ds:SignatureValue>
<ds:KeyInfo>
<ds:X509Data>
<ds:X509Certificate>miib</ds:X509Certificate>
</ds:X509Data>
</ds:KeyInfo>
<ds:Object Id="Nonce">xwQzwEl0CjPAiQeDxwRJdQ==</ds:Object>
</DigitalSignature>
6. Four-Pass Protocol 4. DSKPP Message Formats
In this section, example messages are used to describe parameters, The message formats from the DSKPP XML schema, found in Section 7,
encoding and semantics in a 4-pass DSKPP exchanges. The examples are are explained in this section. Examples can be found in Appendix A.
written using XML. While they are syntactically correct, MAC and The XML format for DSKPP messages have been designed to be
cipher values are fictitious. extensible. However, it is possible that the use of extensions will
harm interoperability; therefore, any use of extensions SHOULD be
carefully considered. For example, if a particular implementation
relies on the presence of a proprietary extension, then it may not be
able to interoperate with independent implementations that have no
knowledge of this extension.
6.1. XML Basics 4.1. General XML Schema Requirements
The DSKPP XML schema can be found in Section 13. Some DSKPP elements Some DSKPP elements rely on the parties being able to compare
rely on the parties being able to compare received values with stored received values with stored values. Unless otherwise noted, all
values. Unless otherwise noted, all elements in this document that elements in this document that have the XML Schema "xs:string" type,
have the XML Schema "xs:string" type, or a type derived from it, MUST or a type derived from it, MUST be compared using an exact binary
be compared using an exact binary comparison. In particular, DSKPP comparison. In particular, DSKPP implementations MUST NOT depend on
implementations MUST NOT depend on case-insensitive string case-insensitive string comparisons, normalization or trimming of
comparisons, normalization or trimming of white space, or conversion white space, or conversion of locale-specific formats such as
of locale-specific formats such as numbers. numbers.
Implementations that compare values that are represented using Implementations that compare values that are represented using
different character encodings MUST use a comparison method that different character encodings MUST use a comparison method that
returns the same result as converting both values to the Unicode returns the same result as converting both values to the Unicode
character encoding, Normalization Form C [UNICODE], and then character encoding, Normalization Form C [UNICODE], and then
performing an exact binary comparison. performing an exact binary comparison.
No collation or sorting order for attributes or element values is No collation or sorting order for attributes or element values is
defined. Therefore, DSKPP implementations MUST NOT depend on defined. Therefore, DSKPP implementations MUST NOT depend on
specific sorting orders for values. specific sorting orders for values.
6.2. Round-Trip #1: <KeyProvClientHello> and <KeyProvServerHello> 4.2. Components of the <KeyProvTrigger> Message
6.2.1. Examples
6.2.1.1. Example Without a Preceding Trigger The DSKPP server MAY initialize the DSKPP protocol by sending a
<KeyProvTrigger> message. This message MAY, e.g., be sent in
response to a user requesting key initialization in a browsing
session.
<?xml version="1.0" encoding="UTF-8"?> <xs:element name="KeyProvTrigger" type="dskpp:KeyProvTriggerType">
<dskpp:KeyProvClientHello Version="1.0" </xs:element>
xmlns:dskpp="urn:ietf:params:xml:ns:keyprov:1.0:protocol" <xs:complexType name="KeyProvTriggerType">
xmlns:pskc="urn:ietf:params:xml:ns:keyprov:1.0:container" <xs:sequence>
xmlns:ds="http://www.w3.org/2000/09/xmldsig#" <xs:choice>
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" <xs:element name="InitializationTrigger"
xsi:schemaLocation="urn:ietf:params:xml:ns:keyprov:1.0:protocol type="dskpp:InitializationTriggerType" />
keyprov-dskpp-1.0.xsd"> <xs:any namespace="##other" processContents="strict" />
<DeviceIdentifierData> </xs:choice>
<DeviceId> </xs:sequence>
<pskc:Manufacturer>ManufacturerABC</pskc:Manufacturer> <xs:attribute name="Version" type="dskpp:VersionType" />
<pskc:SerialNo>XL0000000001234</pskc:SerialNo> </xs:complexType>
<pskc:Model>U2</pskc:Model>
</DeviceId>
</DeviceIdentifierData>
<SupportedKeyTypes>
<Algorithm>urn:ietf:params:xml:schema:keyprov:otpalg#HOTP</Algorithm>
<Algorithm>
http://www.rsa.com/rsalabs/otps/schemas/2005/09/otps-wst#SecurID-AES
</Algorithm>
</SupportedKeyTypes>
<SupportedEncryptionAlgorithms>
<Algorithm>http://www.w3.org/2001/05/xmlenc#rsa_1_5</Algorithm>
<Algorithm>
urn:ietf:params:xml:schema:keyprov:protocol#dskpp-prf-aes
</Algorithm>
</SupportedEncryptionAlgorithms>
<SupportedMacAlgorithms>
<Algorithm>
urn:ietf:params:xml:schema:keyprov:protocol#dskpp-prf-aes
</Algorithm>
</SupportedMacAlgorithms>
<SupportedProtocolVariants><FourPass/></SupportedProtocolVariants>
<SupportedKeyContainers>
<KeyContainerFormat>
urn:ietf:params:xml:schema:keyprov:container#KeyContainer
</KeyContainerFormat>
</SupportedKeyContainers>
</dskpp:KeyProvClientHello>
<?xml version="1.0" encoding="UTF-8"?> <xs:complexType name="InitializationTriggerType">
<dskpp:KeyProvServerHello Version="1.0" SessionID="4114" Status="Success" <xs:sequence>
xmlns:dskpp="urn:ietf:params:xml:ns:keyprov:1.0:protocol" <xs:element minOccurs="0" name="DeviceIdentifierData"
xmlns:pskc="urn:ietf:params:xml:ns:keyprov:1.0:container" type="dskpp:DeviceIdentifierDataType" />
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" <xs:element minOccurs="0" name="KeyID" type="xs:base64Binary" />
xmlns:ds="http://www.w3.org/2000/09/xmldsig#" <xs:element minOccurs="0" name="TokenPlatformInfo"
xsi:schemaLocation="urn:ietf:params:xml:ns:keyprov:1.0:protocol type="dskpp:TokenPlatformInfoType" />
keyprov-dskpp-1.0.xsd"> <xs:element name="TriggerNonce" type="dskpp:NonceType" />
<KeyType> <xs:element minOccurs="0" name="ServerUrl" type="xs:anyURI" />
urn:ietf:params:xml:schema:keyprov:otpalg#SecurID-AES <xs:any minOccurs="0" namespace="##other"
</KeyType> processContents="strict" />
<EncryptionAlgorithm> </xs:sequence>
urn:ietf:params:xml:schema:keyprov:protocol#dskpp-prf-aes </xs:complexType>
</EncryptionAlgorithm>
<MacAlgorithm>
urn:ietf:params:xml:schema:keyprov:protocol#dskpp-prf-aes
</MacAlgorithm>
<EncryptionKey>
<ds:KeyName>KEY-1</ds:KeyName>
</EncryptionKey>
<KeyContainerFormat>
urn:ietf:params:xml:schema:keyprov:container#KeyContainer
</KeyContainerFormat>
<Payload>
<Nonce>qw2ewasde312asder394jw==</Nonce>
</Payload>
</dskpp:KeyProvServerHello>
6.2.1.2. Example Assuming a Preceding Trigger The <KeyProvTrigger> element is intended for the DSKPP client and MAY
inform the DSKPP client about the identifier for the device that
houses the cryptographic module to be initialized, and optionally of
the identifier for the key on that module. The latter would apply to
key renewal. The trigger always contains a nonce to allow the DSKPP
server to couple the trigger with a later DSKPP <KeyProvClientHello>
request. Finally, the trigger MAY contain a URL to use when
contacting the DSKPP server. The <xs:any> elements are for future
extensibility. Any provided <DeviceIdentifierData> or <KeyID> values
MUST be used by the DSKPP client in the subsequent
<KeyProvClientHello> request. The OPTIONAL <TokenPlatformInfo>
element informs the DSKPP client about the characteristics of the
intended cryptographic module platform, and applies in the public-key
variant of DSKPP in situations when the client potentially needs to
decide which one of several modules to initialize.
<?xml version="1.0" encoding="UTF-8"?> 4.3. Components of the <KeyProvClientHello> Request
<dskpp:KeyProvClientHello Version="1.0" This message is the initial message sent from the DSKPP client to the
xmlns:dskpp="urn:ietf:params:xml:ns:keyprov:1.0:protocol" DSKPP server in both variants of the DSKPP.
xmlns:pskc="urn:ietf:params:xml:ns:keyprov:1.0:container"
xmlns:ds="http://www.w3.org/2000/09/xmldsig#"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="urn:ietf:params:xml:ns:keyprov:1.0:protocol
keyprov-dskpp-1.0.xsd">
<DeviceIdentifierData>
<DeviceId>
<pskc:Manufacturer>ManufacturerABC</pskc:Manufacturer>
<pskc:SerialNo>XL0000000001234</pskc:SerialNo>
<pskc:Model>U2</pskc:Model>
</DeviceId>
</DeviceIdentifierData>
<KeyID>SE9UUDAwMDAwMDAx</KeyID>
<TriggerNonce>112dsdfwf312asder394jw==</TriggerNonce>
<SupportedKeyTypes>
<Algorithm>urn:ietf:params:xml:schema:keyprov:otpalg#HOTP</Algorithm>
<Algorithm>
http://www.rsa.com/rsalabs/otps/schemas/2005/09/otps-wst#SecurID-AES
</Algorithm>
</SupportedKeyTypes>
<SupportedEncryptionAlgorithms>
<Algorithm>http://www.w3.org/2001/05/xmlenc#rsa_1_5</Algorithm>
<Algorithm>
urn:ietf:params:xml:schema:keyprov:protocol#dskpp-prf-aes
</Algorithm>
</SupportedEncryptionAlgorithms>
<SupportedMacAlgorithms>
<Algorithm>
urn:ietf:params:xml:schema:keyprov:protocol#dskpp-prf-aes
</Algorithm>
</SupportedMacAlgorithms>
<SupportedProtocolVariants><FourPass/></SupportedProtocolVariants>
<SupportedKeyContainers>
<KeyContainerFormat>
urn:ietf:params:xml:schema:keyprov:container#KeyContainer
</KeyContainerFormat>
</SupportedKeyContainers>
</dskpp:KeyProvClientHello>
<?xml version="1.0" encoding="UTF-8"?> <xs:element name="KeyProvClientHello"
<dskpp:KeyProvServerHello Version="1.0" SessionID="4114" Status="Success" type="dskpp:KeyProvClientHelloPDU">
xmlns:dskpp="urn:ietf:params:xml:ns:keyprov:1.0:protocol" </xs:element>
xmlns:pskc="urn:ietf:params:xml:ns:keyprov:1.0:container"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:ds="http://www.w3.org/2000/09/xmldsig#"
xsi:schemaLocation="urn:ietf:params:xml:ns:keyprov:1.0:protocol
keyprov-dskpp-1.0.xsd">
<KeyType>
http://www.rsa.com/rsalabs/otps/schemas/2005/09/otps-wst#SecurID-AES
</KeyType>
<EncryptionAlgorithm>
urn:ietf:params:xml:schema:keyprov:protocol#dskpp-prf-aes
</EncryptionAlgorithm>
<MacAlgorithm>
urn:ietf:params:xml:schema:keyprov:protocol#dskpp-prf-aes
</MacAlgorithm>
<EncryptionKey>
<ds:KeyName>KEY-1</ds:KeyName>
</EncryptionKey>
<KeyContainerFormat>
urn:ietf:params:xml:schema:keyprov:container#KeyContainer
</KeyContainerFormat>
<Payload>
<Nonce>qw2ewasde312asder394jw==</Nonce>
</Payload>
<Mac MacAlgorithm=
"urn:ietf:params:xml:schema:keyprov:protocol#dskpp-prf-aes">
cXcycmFuZG9tMzEyYXNkZXIzOTRqdw==
</Mac>
</dskpp:KeyProvServerHello>
6.2.2. Components of the <KeyProvClientHello> Request <xs:complexType name="KeyProvClientHelloPDU">
<xs:complexContent mixed="false">
<xs:extension base="dskpp:AbstractRequestType">
<xs:sequence>
<xs:element minOccurs="0" name="DeviceIdentifierData"
type="dskpp:DeviceIdentifierDataType" />
<xs:element minOccurs="0" name="KeyID"
type="xs:base64Binary" />
<xs:element minOccurs="0" name="ClientNonce"
type="dskpp:NonceType" />
<xs:element minOccurs="0" name="TriggerNonce"
type="dskpp:NonceType" />
<xs:element name="SupportedKeyTypes"
type="dskpp:AlgorithmsType" />
<xs:element name="SupportedEncryptionAlgorithms"
type="dskpp:AlgorithmsType" />
<xs:element name="SupportedMacAlgorithms"
type="dskpp:AlgorithmsType" />
<xs:element minOccurs="0" name="SupportedProtocolVariants"
type="dskpp:ProtocolVariantsType" />
<xs:element minOccurs="0" name="SupportedKeyContainers"
type="dskpp:KeyContainersFormatType" />
<xs:element minOccurs="0" name="AuthenticationData"
type="dskpp:AuthenticationDataType" />
<xs:element minOccurs="0" name="Extensions"
type="dskpp:ExtensionsType" />
</xs:sequence>
</xs:extension>
</xs:complexContent>
</xs:complexType>
The components of this message have the following meaning: The components of this message have the following meaning:
o Version: (attribute inherited from the AbstractRequestType type) o Version: (attribute inherited from the AbstractRequestType type)
The highest version of this protocol the client supports. Only The highest version of this protocol the client supports. Only
version one ("1.0") is currently specified. version one ("1.0") is currently specified.
o <DeviceIdentifierData>: An identifier for the cryptographic module o <DeviceIdentifierData>: An identifier for the cryptographic module
as defined in Section 5.3 above. The identifier MUST only be as defined in Section 3.3 above. The identifier MUST only be
present if such shared secrets exist or if the identifier was present if such shared secrets exist or if the identifier was
provided by the server in a <KeyProvTrigger> element (see provided by the server in a <KeyProvTrigger> element (see
Section 12.2.7 below). In the latter case, it MUST have the same Section 6.2.7). In the latter case, it MUST have the same value
value as the identifier provided in that element. as the identifier provided in that element.
o <KeyID>: An identifier for the key that will be overwritten if the o <KeyID>: An identifier for the key that will be overwritten if the
protocol run is successful. The identifier MUST only be present protocol run is successful. The identifier MUST only be present
if the key exists or if the identifier was provided by the server if the key exists or if the identifier was provided by the server
in a <KeyProvTrigger> element, in which case, it MUST have the in a <KeyProvTrigger> element, in which case, it MUST have the
same value as the identifier provided in that element (see a same value as the identifier provided in that element (see a
(Section 9) and Section 12.2.7 below). (Section 4.2) and Section 6.2.7).
o <KeyProvClientNonce>: This is the nonce R, which, when present, o <ClientNonce>: This is the nonce R, which, when present, MUST be
MUST be used by the server when calculating MAC values (see used by the server when calculating MAC values (see below). It is
below). It is RECOMMENDED that clients include this element RECOMMENDED that clients include this element whenever the <KeyID>
whenever the <KeyID> element is present. element is present.
o <TriggerNonce>: This OPTIONAL element MUST be present if and only o <TriggerNonce>: This OPTIONAL element MUST be present if and only
if the DSKPP run was initialized with a <KeyProvTrigger> message if the DSKPP run was initialized with a <KeyProvTrigger> message
(see Section 12.2.7 below), and MUST, in that case, have the same (see Section 6.2.7), and MUST, in that case, have the same value
value as the <TriggerNonce> child of that message. A server using as the <TriggerNonce> child of that message. A server using
nonces in this way MUST verify that the nonce is valid and that nonces in this way MUST verify that the nonce is valid and that
any device or key identifier values provided in the any device or key identifier values provided in the
<KeyProvTrigger> message match the corresponding identifier values <KeyProvTrigger> message match the corresponding identifier values
in the <KeyProvClientHello> message. in the <KeyProvClientHello> message.
o <SupportedKeyTypes>: A sequence of URIs indicating the key types o <SupportedKeyTypes>: A sequence of URLs indicating the key types
for which the cryptographic module is willing to generate keys for which the cryptographic module is willing to generate keys
through DSKPP. through DSKPP.
o <SupportedEncryptionAlgorithms>: A sequence of URIs indicating the o <SupportedEncryptionAlgorithms>: A sequence of URLs indicating the
encryption algorithms supported by the cryptographic module for encryption algorithms supported by the cryptographic module for
the purposes of DSKPP. The DSKPP client MAY indicate the same the purposes of DSKPP. The DSKPP client MAY indicate the same
algorithm both as a supported key type and as an encryption algorithm both as a supported key type and as an encryption
algorithm. algorithm.
o <SupportedMacAlgorithms>: A sequence of URIs indicating the MAC o <SupportedMacAlgorithms>: A sequence of URLs indicating the MAC
algorithms supported by the cryptographic module for the purposes algorithms supported by the cryptographic module for the purposes
of DSKPP. The DSKPP client MAY indicate the same algorithm both of DSKPP. The DSKPP client MAY indicate the same algorithm both
as an encryption algorithm and as a MAC algorithm (e.g., as an encryption algorithm and as a MAC algorithm (e.g.,
urn:ietf:params:xml:schema:keyprov:protocol#dskpp-prf-aes defined http://www.ietf.org/keyprov/dskpp#dskpp-prf-aes, which is defined
in Appendix B). in Appendix C).
o <SupportedProtocolVariants>: This OPTIONAL element is used by the o <SupportedProtocolVariants>: This OPTIONAL element is used by the
DSKPP client to indicate support for four-pass or two-pass DSKPP. DSKPP client to indicate support for four-pass or two-pass DSKPP.
If two-pass support is specified, then <KeyProvClientNonce> MUST If two-pass support is specified, then <KeyProvClientNonce> MUST
be set to nonce R in the <KeyProvClientHello> message unless be set to nonce R in the <KeyProvClientHello> message unless
<TriggerNonce> is already present. <TriggerNonce> is already present.
o <SupportedKeyContainers>: This OPTIONAL element is a sequence of o <SupportedKeyContainers>: This OPTIONAL element is a sequence of
URIs indicating the key container formats supported by the DSKPP URLs indicating the key container formats supported by the DSKPP
client. If this element is not provided, then the DSKPP server client. If this element is not provided, then the DSKPP server
MUST proceed with MUST proceed with "http://www.ietf.org/keyprov/pskc#KeyContainer"
"urn:ietf:params:xml:schema:keyprov:container#KeyContainer" (see (see [PSKC]).
[PSKC]).
o <AuthenticationData>: This OPTIONAL element contains data that the o <AuthenticationData>: This OPTIONAL element contains data that the
DSKPP client uses to authenticate the user or device to the DSKPP DSKPP client uses to authenticate the user or device to the DSKPP
server. The element is set as specified in Section 5.3. server. The element is set as specified in Section 3.3.
o <Extensions>: A sequence of extensions. One extension is defined o <Extensions>: A sequence of extensions. One extension is defined
for this message in this version of DSKPP: the ClientInfoType (see for this mesolsage in this version of DSKPP: the ClientInfoType
Section 10). (see Section 5).
6.2.2.1. The DSKPP Client: The DeviceIdentifierDataType Type Some of the core elements of the message are described below.
4.3.1. The DeviceIdentifierDataType Type
The DeviceIdentifierDataType type is used to uniquely identify the The DeviceIdentifierDataType type is used to uniquely identify the
device that houses the cryptographic module, e.g., a mobile phone. device that houses the cryptographic module, e.g., a mobile phone.
The device identifier allows the DSKPP server to find, e.g., a pre- The device identifier allows the DSKPP server to find, e.g., a pre-
shared transport key for 2-pass DSKPP and/or the correct shared shared transport key for 2-pass DSKPP and/or the correct shared
secret for MAC'ing purposes. The default DeviceIdentifierDataType is secret for MAC'ing purposes. The default DeviceIdentifierDataType is
defined in [PSKC]. defined in [PSKC].
6.2.2.2. Selecting a Protocol Variant: The ProtocolVariantsType Type <xs:complexType name="DeviceIdentifierDataType">
<xs:choice>
<xs:element name="DeviceId" type="pskc:DeviceIdType" />
<xs:any namespace="##other" processContents="strict" />
</xs:choice>
</xs:complexType>
4.3.2. The ProtocolVariantsType Type
The ProtocolVariantsType type is OPTIONAL for a DSKPP client, who MAY The ProtocolVariantsType type is OPTIONAL for a DSKPP client, who MAY
use it to indicate the number of passes of the DSKPP protocol that it use it to indicate the number of passes of the DSKPP protocol that it
supports. The ProtocolVariantsType MAY be used to indicate support supports. The ProtocolVariantsType MAY be used to indicate support
for 4-pass or 2-pass DSKPP. Because 1-pass DSKPP does not include a for 4-pass or 2-pass DSKPP. If the ProtocolVariantsType is not used,
client request to the server, the ProtocolVariantsType type MAY NOT then the DSKPP server will proceed with ordinary 4-pass DSKPP.
be used to indicate support for 1-pass DSKPP. If the However, if it does not support 4-pass DSKPP, then the server MUST
ProtocolVariantsType is not used, then the DSKPP server will proceed find a suitable two-pass variation or else the protocol run will
with ordinary 4-pass DSKPP. However, it does not support 4-pass fail.
DSKPP, then the server MUST find a suitable two-pass variant or else
the protocol run will fail.
The TwoPassSupportType type signals client support for the 2-pass Selecting the "TwoPass" element signals client support for the 2-pass
version of DSKPP, informs the server of supported two-pass variants, version of DSKPP, informs the server of supported two-pass key
and provides OPTIONAL payload data to the DSKPP server. The payload protection methods, and provides OPTIONAL payload data to the DSKPP
is sent in an opportunistic fashion, and MAY be discarded by the server. The payload is sent in an opportunistic fashion, and MAY be
DSKPP server if the server does not support the two-pass variant the discarded by the DSKPP server if the server does not support thekey
payload is associated with. The elements of this type have the protection method with which the payload is associated.
following meaning:
o <SupportedKeyInitializationMethod>: A two-pass key initialization <xs:complexType name="ProtocolVariantsType">
method supported by the DSKPP client. Multiple supported methods <xs:sequence>
MAY be present, in which case they MUST be listed in order of <xs:element minOccurs="0" name="FourPass" />
precedence. <xs:element minOccurs="0" name="TwoPass"
type="dskpp:KeyProtectionDataType"/>
</xs:sequence>
</xs:complexType>
<xs:complexType name="KeyProtectionDataType">
<xs:complexContent mixed="false">
<xs:sequence maxOccurs="unbounded">
<xs:element name="SupportedKeyProtectionMethod" type="xs:anyURI"/>
<xs:element name="Payload" type="dskpp:PayloadType"
</xs:sequence>
</xs:complexContent>
</xs:complexType>
The elements of this type have the following meaning:
o <SupportedKeyProtectionMethod>: A two-pass key protection method
supported by the DSKPP client. Multiple supported methods MAY be
present, in which case they MUST be listed in order of precedence.
o <Payload>: An OPTIONAL payload associated with each supported key o <Payload>: An OPTIONAL payload associated with each supported key
initialization method. protection method.
A DSKPP client that indicates support for two-pass DSKPP MUST also A DSKPP client that indicates support for two-pass DSKPP MUST also
include the nonce R in its <KeyProvClientHello> message (this will include the nonce R in its <KeyProvClientHello> message (this will
enable the client to verify that the DSKPP server it is communicating enable the client to verify that the DSKPP server it is communicating
with is alive). with is alive).
6.2.2.3. Selecting a Key Container Format: The KeyContainersFormatType 4.3.3. The KeyContainersFormatType Type
Type
The OPTIONAL KeyContainersFormatType type is a list of type-value The OPTIONAL KeyContainersFormatType type is a list of type-value
pairs that a DSKPP client or server MAY use to define key container pairs that a DSKPP client or server MAY use to define key container
formats it supports. Key container formats are identified through formats it supports. Key container formats are identified through
URIs, e.g., the PSKC KeyContainer URI URLs, e.g., the PSKC KeyContainer URL
"urn:ietf:params:xml:schema:keyprov:container#KeyContainer" (see "http://www.ietf.org/keyprov/pskc#KeyContainer" (see [PSKC]).
[PSKC]).
6.2.2.4. Selecting a Client and Server Authentication Mechanism: The <xs:complexType name="KeyContainersFormatType">
AuthenticationDataType Type <xs:sequence maxOccurs="unbounded">
<xs:element name="KeyContainerFormat"
type="dskpp:KeyContainerFormatType"/>
</xs:sequence>
</xs:complexType>
<xs:simpleType name="KeyContainerFormatType">
<xs:restriction base="xs:anyURI" />
</xs:simpleType>
4.3.4. The AuthenticationDataType Type
The OPTIONAL AuthenticationDataType type is used by DSKPP clients and The OPTIONAL AuthenticationDataType type is used by DSKPP clients and
server to carry authentication values in DSKPP messages. The element server to carry authentication values in DSKPP messages. The element
MAY contain a device certificate or MAC derived from an MAY contain a MAC derived from an authentication code as follows:
authentication code as follows:
a. A DSKPP client MAY include a one-time use AuthenticationCode that a. A DSKPP client MAY include a one-time use AuthenticationCode that
was given by the issuer to the user for acquiring a symmetric was given by the issuer to the user for acquiring a symmetric
key. An AuthenticationCode MAY or MAY NOT contain alphanumeric key. An AuthenticationCode MAY contain alphanumeric characters
characters in addition to numeric digits depending on the device in addition to numeric digits depending on the device type and
type and policy of the issuer. For example, if the device is a policy of the issuer. For example, if the device is a mobile
mobile phone, a code that the user enters on the keypad would phone, a code that the user enters on the keypad would typically
typically be restricted to numeric digits for ease of use. An be restricted to numeric digits for ease of use. An
authentication code MAY be sent to the DSKPP server as MAC data authentication code MAY be sent to the DSKPP server as MAC data
calculated according to section Section 5.3.3. calculated according to section Section 3.3.2.
b. A DSKPP client MAY contain Authentication Data consisting of b. A DSKPP server MAY use the AuthenticationDataType element
signed data of client Nonce with a client certificate's private
key. A service provider may have a policy to issue symmetric
keys for a device only if it has a trusted device certificate.
An authentication code isn't required in this case.
c. A DSKPP server MAY use the AuthenticationDataType element
AuthenticationCodeMac to carry a MAC for authenticating itself to AuthenticationCodeMac to carry a MAC for authenticating itself to
the client. For example, when a successful 1- or 2-pass DSKPP the client. For example, when a successful 2-pass DSKPP protocol
protocol run will result in an existing key being replaced, then run will result in an existing key being replaced, then the DSKPP
the DSKPP server MUST include a MAC proving to the DSKPP client server MUST include a MAC proving to the DSKPP client that the
that the server knows the value of the key it is about to server knows the value of the key it is about to replace.
replace.
The element of the AuthenticationDataType type have the following <xs:complexType name="AuthenticationDataType">
<xs:sequence>
<xs:element minOccurs="0" name="ClientID"
type="dskpp:IdentifierType" />
<xs:element name="AuthenticationCodeMac"
type="dskpp:AuthenticationCodeMacType" />
</xs:sequence>
</xs:complexType>
<xs:complexType name="AuthenticationCodeMacType">
<xs:sequence>
<xs:element minOccurs="0" name="Nonce" type="dskpp:NonceType" />
<xs:element minOccurs="0" name="IterationCount" type="xs:int" />
<xs:element name="Mac" type="dskpp:MacType" />
</xs:sequence>
</xs:complexType>
The elements of the AuthenticationDataType type have the following
meaning: meaning:
o <ClientID>: A requester's identifier. The value MAY be a user ID, o <ClientID>: A requester's identifier. The value MAY be a user ID,
a device ID, or a keyID associated with the requester's a device ID, or a keyID associated with the requester's
authentication value. When the authentication data is based on a authentication value. Ifa <KeyProvTrigger> message was provided
certificate, <ClientID> can be omitted, as the certificate itself by the server to initiate the DSKPP protocol run, <ClientID> can
is typically sufficient to identify the requester. Also, if a be omitted, as the DeviceID, KeyID, and/or nonce provided in the
<KeyProvTrigger> message was provided by the server to initiate
the DSKPP protocol run, <ClientID> can be omitted, as the
DeviceID, KeyID, and/or nonce provided in the
<InitializationTriggerType> element ought to be sufficient to <InitializationTriggerType> element ought to be sufficient to
identify the requester. identify the requester.
o <AuthenticationCodeMac>: An authentication MAC and OPTIONAL o <AuthenticationCodeMac>: An authentication MAC and additional
additional information (e.g., MAC algorithm). The value could be information (e.g., MAC algorithm). This MAC MAY be derived as
a one-time use value sent as a MAC value to the DSKPP server; or, follows:
it could be a MAC value sent to the DSKPP client. Refer to * User Authentication: A DSKPP client MAY include a one-time use
section Section 5.3.3 for calculation of MAC with an AuthenticationCode that was given by the issuer to the user for
authentication code. acquiring a symmetric key. An AuthenticationCode MAY contain
o <DigitalSignature>: Client nonce R_C signed using the device alphanumeric characters in addition to numeric digits depending
certificate and sent in KeyProvClientHello for two-pass protocol on the device type and policy of the issuer. For example, if
or in KeyProvClientNonce for four-pass protocol. the device is a mobile phone, a code that the user enters on
the keypad would typically be restricted to numeric digits for
ease of use. An authentication code MAY be sent to the DSKPP
server as MAC data calculated as described in section
Section 3.3.2.
* Server Authorization (two-pass DSKPP only): A DSKPP server MUST
include a MAC in its <KeyProvServerFinished> message as proof
that the DSKPP server is authorized to provide a new key to the
cryptographic module. For example, when a successful 2-pass
DSKPP protocol run will result in an existing key being
replaced, then the DSKPP server MUST include the
AuthenticationDataType element's AuthenticationCodeMac in its
<KeyProvServerFinished> message. For more information, refer
to Section 3.2.3.2.
6.2.3. Components of the <KeyProvServerHello> Response 4.4. Components of the <KeyProvServerHello> Response (Used Only in
Four-Pass DSKPP)
This message is the first message sent from the DSKPP server to the In a four-pass exchange, this message is the first message sent from
DSKPP client (assuming a trigger message has not been sent to the DSKPP server to the DSKPP client (assuming a trigger message has
initiate the protocol, in which case, this message is the second not been sent to initiate the protocol, in which case, this message
message sent from the DSKPP server to the DSKPP client). It is sent is the second message sent from the DSKPP server to the DSKPP
upon reception of a <KeyProvClientHello> message. The components of client). It is sent upon reception of a <KeyProvClientHello>
this message have the following meaning: message.
<xs:element name="KeyProvServerHello"
type="dskpp:KeyProvServerHelloPDU">
</xs:element>
<xs:complexType name="KeyProvServerHelloPDU">
<xs:complexContent mixed="false">
<xs:extension base="dskpp:AbstractResponseType">
<xs:sequence minOccurs="0">
<xs:element name="KeyType" type="dskpp:AlgorithmType" />
<xs:element name="EncryptionAlgorithm"
type="dskpp:AlgorithmType" />
<xs:element name="MacAlgorithm" type="dskpp:AlgorithmType" />
<xs:element name="EncryptionKey" type="ds:KeyInfoType" />
<xs:element name="KeyContainerFormat"
type="dskpp:KeyContainerFormatType" />
<xs:element name="Payload" type="dskpp:PayloadType" />
<xs:element minOccurs="0" name="Extensions"
type="dskpp:ExtensionsType" />
<xs:element minOccurs="0" name="Mac" type="dskpp:MacType" />
</xs:sequence>
</xs:extension>
</xs:complexContent>
</xs:complexType>
The components of this message have the following meaning:
o Version: (attribute inherited from the AbstractResponseType type) o Version: (attribute inherited from the AbstractResponseType type)
The version selected by the DSKPP server. MAY be lower than the The version selected by the DSKPP server. MAY be lower than the
version indicated by the DSKPP client, in which case, local policy version indicated by the DSKPP client, in which case, local policy
at the client MUST determine whether or not to continue the at the client MUST determine whether or not to continue the
session. session.
o SessionID: (attribute inherited from the AbstractResponseType o SessionID: (attribute inherited from the AbstractResponseType
type) An identifier for this session. type) An identifier for this session.
o Status: (attribute inherited from the AbstractResponseType type) o Status: (attribute inherited from the AbstractResponseType type)
Return code for the <KeyProvClientHello>. If Status is not Return code for the <KeyProvClientHello>. If Status is not
skipping to change at page 45, line 45 skipping to change at page 45, line 21
alternative of ds:KeyInfoType) or an identifier for a shared alternative of ds:KeyInfoType) or an identifier for a shared
secret key (the <ds:KeyName> alternative of ds:KeyInfoType). secret key (the <ds:KeyName> alternative of ds:KeyInfoType).
o <KeyContainerFormat>: The key container format type to be used by o <KeyContainerFormat>: The key container format type to be used by
the DSKPP server. The default setting relies on the the DSKPP server. The default setting relies on the
KeyContainerType element defined in KeyContainerType element defined in
"urn:ietf:params:xml:schema:keyprov:container" [PSKC]. "urn:ietf:params:xml:schema:keyprov:container" [PSKC].
o <Payload>: The actual payload. For this version of the protocol, o <Payload>: The actual payload. For this version of the protocol,
only one payload is defined: the pseudorandom string R_S. only one payload is defined: the pseudorandom string R_S.
o <Extensions>: A list of server extensions. Two extensions are o <Extensions>: A list of server extensions. Two extensions are
defined for this message in this version of DSKPP: the defined for this message in this version of DSKPP: the
ClientInfoType and the ServerInfoType (see Section 10). ClientInfoType and the ServerInfoType (see Section 5).
o <Mac>: The MAC MUST be present if the DSKPP run will result in the o <Mac>: The MAC MUST be present if the DSKPP run will result in the
replacement of an existing symmetric key with a new one (i.e., if replacement of an existing symmetric key with a new one (i.e., if
the <KeyID> element was present in the <ClientHello message). In the <KeyID> element was present in the <ClientHello message). In
this case, the DSKPP server MUST prove to the cryptographic module this case, the DSKPP server MUST prove to the cryptographic module
that it is authorized to replace it. that it is authorized to replace it.
The DSKPP client MUST verify the MAC if the successful execution 4.5. Components of a <KeyProvClientNonce> Request (Used Only in Four-
of the protocol will result in the replacement of an existing Pass DSKPP)
symmetric key with a newly generated one. The DSKPP client MUST
terminate the DSKPP session if the MAC does not verify, and MUST
delete any nonces, keys, and/or secrets associated with the failed
run of the DSKPP protocol.
The MacType's MacAlgorithm attribute MUST, when present, identify
the negotiated MAC algorithm.
6.3. Round-Trip #2: <KeyProvClientNonce> and <KeyProvServerFinished>
6.3.1. Examples
6.3.1.1. Example Using Default Encryption
This message contains the nonce chosen by the cryptographic module,
R_C, encrypted by the specified encryption key and encryption
algorithm.
<?xml version="1.0" encoding="UTF-8"?>
<dskpp:KeyProvClientNonce Version="1.0" SessionID="4114"
xmlns:dskpp="urn:ietf:params:xml:ns:keyprov:1.0:protocol"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="urn:ietf:params:xml:ns:keyprov:1.0:protocol
keyprov-dskpp-1.0.xsd">
<EncryptedNonce>VXENc+Um/9/NvmYKiHDLaErK0gk=</EncryptedNonce>
<AuthenticationData>
<ClientID>31300257</ClientID>
<AuthenticationCodeMac>
<IterationCount>512</IterationCount>
<Mac>4bRJf9xXd3KchKoTenHJiw==</Mac>
</AuthenticationCodeMac>
</AuthenticationData>
</dskpp:KeyProvClientNonce>
<?xml version="1.0" encoding="UTF-8"?>
<dskpp:KeyProvServerFinished Version="1.0" SessionID="4114" Status="Success"
xmlns:dskpp="urn:ietf:params:xml:ns:keyprov:1.0:protocol"
xmlns:pskc="urn:ietf:params:xml:ns:keyprov:1.0:container"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="urn:ietf:params:xml:ns:keyprov:1.0:protocol
keyprov-dskpp-1.0.xsd">
<KeyContainer>
<KeyContainer Version="1.0">
<pskc:DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#hmac-sha1"/>
<pskc:Device>
<pskc:Key
KeyAlgorithm=
"http://www.rsa.com/rsalabs/otps/schemas/2005/09/otps-wst#SecurID-AES"
KeyId="XL0000000001234">
<pskc:Issuer>CredentialIssuer</pskc:Issuer>
<pskc:Usage otp="true">
<pskc:ResponseFormat format="DECIMAL" length="6"/>
</pskc:Usage>
<pskc:FriendlyName>MyFirstToken</pskc:FriendlyName>
<pskc:Data Name="TIME">
<pskc:Value>AAAAADuaygA=</pskc:Value>
</pskc:Data>
<pskc:Expiry>10/30/2012</pskc:Expiry>
</pskc:Key>
</pskc:Device>
</KeyContainer>
</KeyContainer>
<Mac
MacAlgorithm="urn:ietf:params:xml:schema:keyprov:protocol#dskpp-prf-aes">
miidfasde312asder394jw==
</Mac>
</dskpp:KeyProvServerFinished>
6.3.2. Components of a <KeyProvClientNonce> Request In a four-pass DSKPP exchange, this message contains the nonce R_C
that was chosen by the cryptographic module, and encrypted by the
negotiated encryption key and encryption algorith
<xs:element name="KeyProvClientNonce"
type="dskpp:KeyProvClientNoncePDU">
</xs:element>
<xs:complexType name="KeyProvClientNoncePDU">
<xs:complexContent mixed="false">
<xs:extension base="dskpp:AbstractRequestType">
<xs:sequence>
<xs:element name="EncryptedNonce" type="xs:base64Binary" />
<xs:element minOccurs="0" name="AuthenticationData"
type="dskpp:AuthenticationDataType" />
<xs:element minOccurs="0" name="Extensions"
type="dskpp:ExtensionsType" />
</xs:sequence>
<xs:attribute name="SessionID" type="dskpp:IdentifierType"
use="required" />
</xs:extension>
</xs:complexContent>
</xs:complexType>
The components of this message have the following meaning: The components of this message have the following meaning:
o Version: (inherited from the AbstractRequestType type) MUST be the o Version: (inherited from the AbstractRequestType type) MUST be the
same version as in the <KeyProvServerHello> message. same version as in the <KeyProvServerHello> message.
o <SessionID>: MUST have the same value as the SessionID attribute o <SessionID>: (attribute inherited from the AbstractResponseType
in the received <KeyProvServerHello> message. type) MUST have the same value as the SessionID attribute in the
received <KeyProvServerHello> message.
o <EncryptedNonce>: The nonce generated and encrypted by the o <EncryptedNonce>: The nonce generated and encrypted by the
cryptographic module. The encryption MUST be made using the cryptographic module. The encryption MUST be made using the
selected encryption algorithm and identified key, and as specified selected encryption algorithm and identified key, and as specified
in Section 5.1. in Section 3.4.
o <AuthenticationData>: The authentication data value MUST be set as o <AuthenticationData>: The authentication data value MUST be set as
specified in Section 5.3 and Section 6.2.2.4. specified in Section 3.3 and Section 4.3.4.
o <Extensions>: A list of extensions. Two extensions are defined o <Extensions>: A list of extensions. Two extensions are defined
for this message in this version of DSKPP: the ClientInfoType and for this message in this version of DSKPP: the ClientInfoType and
the ServerInfoType (see Section 10) the ServerInfoType (see Section 5)
6.3.3. Components of a <KeyProvServerFinished> Response 4.6. Components of a <KeyProvServerFinished> Response
This message is the last message of the DSKPP protocol run. In a This message is the last message of the DSKPP protocol run. In a
4-pass exchange, the DSKPP server sends this message in response to a 4-pass exchange, the DSKPP server sends this message in response to a
<KeyProvClientNonce> message, whereas in a 2-pass exchange, the DSKPP <KeyProvClientNonce> message, whereas in a 2-pass exchange, the DSKPP
server sends this message in response to a <KeyProvClientHello> server sends this message in response to a <KeyProvClientHello>
message. In a 1-pass exchange, the DSKPP server sends only this
message to the client. The components of this message have the
following meaning:
o Version: (inherited from the AbstractResponseType type) The DSKPP
version used in this session.
o SessionID: (inherited from the AbstractResponseType type) The
previously established identifier for this session.
o Status: (inherited from the AbstractResponseType type) Return code
for the <KeyProvServerFinished> message. If Status is not
"Success", only the Status, SessionID, and Version attributes will
be present (the presence of the SessionID attribute is dependent
on the type of reported error); otherwise, all the other elements
MUST be present as well. In this latter case, the
<KeyProvServerFinished> message can be seen as a "Commit" message,
instructing the cryptographic module to store the generated key
and associate the given key identifier with this key.
o <KeyContainer>: The key container containing symmetric key values
(in the case of a 2- or 1-pass exchange) and configuration data.
The default container format is based on the KeyContainerType type
from PSKC, as defined in [PSKC].
o <Extensions>: A list of extensions chosen by the DSKPP server.
For this message, this version of DSKPP defines one extension, the
ClientInfoType (see Section 10).
o <Mac>: To avoid a false "Commit" message causing the cryptographic
module to end up in an initialized state for which the server does
not know the stored key, <KeyProvServerFinished> messages MUST
always be authenticated with a MAC. The MAC MUST be made using
the already established MAC algorithm.
When receiving a <KeyProvServerFinished> message with
Status="Success" for which the MAC verifies, the DSKPP client MUST
associate the generated key K_TOKEN with the provided key
identifier and store this data permanently. After this operation,
it MUST NOT be possible to overwrite the key unless knowledge of
an authorizing key is proven through a MAC on a later
<KeyProvServerHello> (and <KeyProvServerFinished>) message.
The DSKPP client MUST verify the MAC. The DSKPP client MUST
terminate the DSKPP session if the MAC does not verify, and MUST,
in this case, also delete any nonces, keys, and/or secrets
associated with the failed run of the DSKPP protocol.
The MacType's MacAlgorithm attribute MUST, when present, identify
the negotiated MAC algorithm.
6.4. DSKPP Server Results: The StatusCode Type
The StatusCode type enumerates all possible return codes. Upon
transmission or receipt of a message for which the Status attribute's
value is not "Success" or "Continue", the default behavior, unless
explicitly stated otherwise below, is that both the DSKPP server and
the DSKPP client MUST immediately terminate the DSKPP session. DSKPP
servers and DSKPP clients MUST delete any secret values generated as
a result of failed runs of the DSKPP protocol. Session identifiers
MAY be retained from successful or failed protocol runs for replay
detection purposes, but such retained identifiers MUST NOT be reused
for subsequent runs of the protocol.
When possible, the DSKPP client SHOULD present an appropriate error
message to the user.
These status codes are valid in all 4-Pass DSKPP Response messages
unless explicitly stated otherwise:
o "Continue" indicates that the DSKPP server is ready for a
subsequent request from the DSKPP client. It cannot be sent in
the server's final message.
o "Success" indicates successful completion of the DSKPP session.
It can only be sent in the server's final message.
o "Abort" indicates that the DSKPP server rejected the DSKPP
client's request for unspecified reasons.
o "AccessDenied" indicates that the DSKPP client is not authorized
to contact this DSKPP server.
o "MalformedRequest" indicates that the DSKPP server failed to parse
the DSKPP client's request.
o "UnknownRequest" indicates that the DSKPP client made a request
that is unknown to the DSKPP server.
o "UnknownCriticalExtension" indicates that a critical DSKPP
extension (see below) used by the DSKPP client was not supported
or recognized by the DSKPP server.
o "UnsupportedVersion" indicates that the DSKPP client used a DSKPP
protocol version not supported by the DSKPP server. This error is
only valid in the DSKPP server's first response message.
o "NoSupportedKeyTypes" indicates that the DSKPP client only
suggested key types that are not supported by the DSKPP server.
This error is only valid in the DSKPP server's first response
message. message.
o "NoSupportedEncryptionAlgorithms" indicates that the DSKPP client <xs:element name="KeyProvServerFinished"
only suggested encryption algorithms that are not supported by the type="dskpp:KeyProvServerFinishedPDU">
DSKPP server. This error is only valid in the DSKPP server's </xs:element>
first response message. <xs:complexType name="KeyProvServerFinishedPDU">
o "NoSupportedMacAlgorithms" indicates that the DSKPP client only <xs:complexContent mixed="false">
suggested MAC algorithms that are not supported by the DSKPP <xs:extension base="dskpp:AbstractResponseType">
server. This error is only valid in the DSKPP server's first <xs:sequence minOccurs="0">
response message. <xs:element name="KeyContainer"
o "NoProtocolVariants" indicates that the DSKPP client only type="dskpp:KeyContainerType" />
suggested a protocol variant (either 2-pass or 4-pass) that is not <xs:element minOccurs="0" name="Extensions"
supported by the DSKPP server. This error is only valid in the type="dskpp:ExtensionsType" />
DSKPP server's first response messagei <xs:element name="Mac" type="dskpp:MacType" />
o "NoSupportedKeyContainers" indicates that the DSKPP client only <xs:element minOccurs="0" name="AuthenticationData"
suggested key container formats that are not supported by the type="dskpp:AuthenticationDataType" />
DSKPP server. This error is only valid in the DSKPP server's </xs:sequence>
first response message. </xs:extension>
o "AuthenticationDataMissing" indicates that the DSKPP client didn't </xs:complexContent>
provide authentication data that the DSKPP server required. </xs:complexType>
o "AuthenticationDataInvalid" indicates that the DSKPP client
supplied user or device authentication data that the DSKPP server
failed to validate.
o "InitializationFailed" indicates that the DSKPP server could not
generate a valid key given the provided data. When this status
code is received, the DSKPP client SHOULD try to restart DSKPP, as
it is possible that a new run will succeed.
o "ProvisioningPeriodExpired" indicates that the provisioning period
set by the DSKPP server has expired. When the status code is
received, the DSKPP client SHOULD report the key initialization
failure reason to the user and the user MUST register with the
DSKPP server to initialize a new key.
7. Two-Pass Protocol
In this section, example messages are used to describe parameters,
encoding and semantics in a 2-pass DSKPP exchanges. The examples are
written using XML. While they are syntactically correct, MAC and
cipher values are fictitious.
7.1. XML Basics
The DSKPP XML schema can be found in Section 13. Some DSKPP elements
rely on the parties being able to compare received values with stored
values. Unless otherwise noted, all elements in this document that
have the XML Schema "xs:string" type, or a type derived from it, MUST
be compared using an exact binary comparison. In particular, DSKPP
implementations MUST NOT depend on case-insensitive string
comparisons, normalization or trimming of white space, or conversion
of locale-specific formats such as numbers.
Implementations that compare values that are represented using
different character encodings MUST use a comparison method that
returns the same result as converting both values to the Unicode
character encoding, Normalization Form C [UNICODE], and then
performing an exact binary comparison.
No collation or sorting order for attributes or element values is
defined. Therefore, DSKPP implementations MUST NOT depend on
specific sorting orders for values.
7.2. Round-Trip #1: <KeyProvClientHello> and <KeyProvServerFinished>
7.2.1. Examples
7.2.1.1. Example Using the Key Transport Profile
The client indicates support all the Key Transport, Key Wrap, and
Passphrase-Based Key Wrap profiles (see Section 11):
<?xml version="1.0" encoding="UTF-8"?>
<dskpp:KeyProvClientHello Version="1.0"
xmlns:dskpp="urn:ietf:params:xml:ns:keyprov:1.0:protocol"
xmlns:pskc="urn:ietf:params:xml:ns:keyprov:1.0:container"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:ds="http://www.w3.org/2000/09/xmldsig#"
xsi:schemaLocation="urn:ietf:params:xml:ns:keyprov:1.0:protocol
keyprov-dskpp-1.0.xsd">
<DeviceIdentifierData>
<DeviceId>
<pskc:Manufacturer>ManufacturerABC</pskc:Manufacturer>
<pskc:SerialNo>XL0000000001234</pskc:SerialNo>
<pskc:Model>U2</pskc:Model>
</DeviceId>
</DeviceIdentifierData>
<ClientNonce>xwQzwEl0CjPAiQeDxwRJdQ==</ClientNonce>
<SupportedKeyTypes>
<Algorithm>urn:ietf:params:xml:schema:keyprov:otpalg#HOTP</Algorithm>
<Algorithm>
http://www.rsa.com/rsalabs/otps/schemas/2005/09/otps-wst#SecurID-AES
</Algorithm>
</SupportedKeyTypes>
<SupportedEncryptionAlgorithms>
<Algorithm>http://www.w3.org/2001/05/xmlenc#rsa_1_5</Algorithm>
<Algorithm>http://www.w3.org/2001/04/xmlenc#kw-aes128</Algorithm>
<Algorithm>urn:ietf:params:xml:schema:keyprov:protocol#dskpp-prf-aes</Algorithm>
</SupportedEncryptionAlgorithms>
<SupportedMacAlgorithms>
<Algorithm>urn:ietf:params:xml:schema:keyprov:protocol#dskpp-prf-aes</Algorithm>
</SupportedMacAlgorithms>
<SupportedProtocolVariants>
<TwoPass>
<SupportedKeyInitializationMethod>
urn:ietf:params:xml:schema:keyprov:protocol#wrap
</SupportedKeyInitializationMethod>
<Payload xsi:type="ds:KeyInfoType">
<ds:KeyName>Key_001</ds:KeyName>
</Payload>
<SupportedKeyInitializationMethod>
urn:ietf:params:xml:schema:keyprov:protocol#transport
</SupportedKeyInitializationMethod>
<SupportedKeyInitializationMethod>
urn:ietf:params:xml:schema:keyprov:protocol#passphrase-wrap
</SupportedKeyInitializationMethod>
<Payload xsi:type="ds:KeyInfoType">
<ds:X509Data>
<ds:X509Certificate>miib</ds:X509Certificate>
</ds:X509Data>
</Payload>
</TwoPass>
</SupportedProtocolVariants>
<SupportedKeyContainers>
<KeyContainerFormat>
urn:ietf:params:xml:schema:keyprov:container#KeyContainer
</KeyContainerFormat>
</SupportedKeyContainers>
<AuthenticationData>
<DigitalSignature>
<ds:SignedInfo>
<ds:CanonicalizationMethod
Algorithm="http://www.w3.org/TR/2001/REC-xml-c14n-20010315" />
<ds:SignatureMethod Algorithm="http://www.w3.org/2000/09/xmldsig#rsa-sha1"/>
<ds:Reference URI="#Nonce">
<ds:DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#sha1"/>
<ds:DigestValue></ds:DigestValue>
</ds:Reference>
</ds:SignedInfo>
<ds:SignatureValue></ds:SignatureValue>
<ds:KeyInfo>
<ds:X509Data>
<ds:X509Certificate>miib</ds:X509Certificate>
</ds:X509Data>
</ds:KeyInfo>
<ds:Object Id="Nonce">xwQzwEl0CjPAiQeDxwRJdQ==</ds:Object>
</DigitalSignature>
</AuthenticationData>
</dskpp:KeyProvClientHello>
In this example, the server responds to the previous request using
the key transport profile.
<?xml version="1.0" encoding="UTF-8"?>
<dskpp:KeyProvServerFinished Version="1.0" SessionID="4114" Status="Success"
xmlns:dskpp="urn:ietf:params:xml:ns:keyprov:1.0:protocol"
xmlns:pskc="urn:ietf:params:xml:ns:keyprov:1.0:container"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:ds="http://www.w3.org/2000/09/xmldsig#"
xmlns:xenc="http://www.w3.org/2001/04/xmlenc#"
xsi:schemaLocation="urn:ietf:params:xml:ns:keyprov:1.0:protocol
keyprov-dskpp-1.0.xsd">
<KeyContainer>
<KeyContainer Version="1.0">
<pskc:EncryptionMethod
Algorithm="http://www.w3.org/2001/05/xmlenc#rsa_1_5">
<pskc:KeyInfo>
<ds:X509Data>
<ds:X509Certificate>miib</ds:X509Certificate>
</ds:X509Data>
</pskc:KeyInfo>
</pskc:EncryptionMethod>
<pskc:DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#hmac-sha1"/>
<Device xmlns="urn:ietf:params:xml:ns:keyprov:1.0:container">
<Key KeyAlgorithm="urn:ietf:params:xml:schema:keyprov:otpalg#HOTP"
KeyId="SDU312345678">
<Issuer>CredentialIssuer</Issuer>
<Usage otp="true">
<ResponseFormat format="DECIMAL" length="6"/>
</Usage>
<FriendlyName>MyFirstToken</FriendlyName>
<Data Name="SECRET">
<Value>
7JHUyp3azOkqJENSsh6b2vxXzwGBYypzJxEr+ikQAa229KV/BgZhGA==
</Value>
<ValueDigest>
i8j+kpbfKQsSlwmJYS99lQ==
</ValueDigest>
</Data>
<Data Name="COUNTER">
<Value>AAAAAAAAAAA=</Value>
</Data>
<Expiry>10/30/2012</Expiry>
</Key>
</Device>
</KeyContainer>
</KeyContainer>
<Mac
MacAlgorithm="urn:ietf:params:xml:schema:keyprov:protocol#dskpp-prf-aes">
miidfasde312asder394jw==
</Mac>
<AuthenticationData>
<AuthenticationCodeMac>
<Mac>4bRJf9xXd3KchKoTenHJiw==</Mac>
</AuthenticationCodeMac>
</AuthenticationData>
</dskpp:KeyProvServerFinished>
7.2.1.2. Example Using the Key Wrap Profile
The client sends a request that specifies a shared key to protect the
K_TOKEN, and the server responds using the Key Wrap Profile.
Authentication data in this example is basing on an authentication
code rather than a device certificate.
<?xml version="1.0" encoding="UTF-8"?>
<dskpp:KeyProvClientHello Version="1.0"
xmlns:dskpp="urn:ietf:params:xml:ns:keyprov:1.0:protocol"
xmlns:pskc="urn:ietf:params:xml:ns:keyprov:1.0:container"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:ds="http://www.w3.org/2000/09/xmldsig#"
xmlns:pkcs-5="http://www.rsasecurity.com/rsalabs/pkcs/schemas/pkcs-5v2-0#"
xsi:schemaLocation="urn:ietf:params:xml:ns:keyprov:1.0:protocol
keyprov-dskpp-1.0.xsd">
<DeviceIdentifierData>
<DeviceId>
<pskc:Manufacturer>ManufacturerABC</pskc:Manufacturer>
<pskc:SerialNo>XL0000000001234</pskc:SerialNo>
<pskc:Model>U2</pskc:Model>
</DeviceId>
</DeviceIdentifierData>
<ClientNonce>xwQzwEl0CjPAiQeDxwRJdQ==</ClientNonce>
<SupportedKeyTypes>
<Algorithm>urn:ietf:params:xml:schema:keyprov:otpalg#HOTP</Algorithm>
<Algorithm>
http://www.rsa.com/rsalabs/otps/schemas/2005/09/otps-wst#SecurID-AES
</Algorithm>
</SupportedKeyTypes>
<SupportedEncryptionAlgorithms>
<Algorithm>http://www.w3.org/2001/05/xmlenc#rsa_1_5</Algorithm>
<Algorithm>http://www.w3.org/2001/04/xmlenc#kw-aes128</Algorithm>
<Algorithm>
http://www.rsasecurity.com/rsalabs/pkcs/schemas/pkcs-5#pbes2
</Algorithm>
<Algorithm>
urn:ietf:params:xml:schema:keyprov:protocol#dskpp-prf-aes
</Algorithm>
</SupportedEncryptionAlgorithms>
<SupportedMacAlgorithms>
<Algorithm>
urn:ietf:params:xml:schema:keyprov:protocol#dskpp-prf-aes
</Algorithm>
</SupportedMacAlgorithms>
<SupportedProtocolVariants>
<TwoPass>
<SupportedKeyInitializationMethod>
urn:ietf:params:xml:schema:keyprov:protocol#wrap
</SupportedKeyInitializationMethod>
<Payload xsi:type="ds:KeyInfoType">
<ds:KeyName>Key_001</ds:KeyName>
</Payload>
</TwoPass>
</SupportedProtocolVariants>
<SupportedKeyContainers>
<KeyContainerFormat>
urn:ietf:params:xml:schema:keyprov:container#KeyContainer
</KeyContainerFormat>
</SupportedKeyContainers>
<AuthenticationData>
<ClientID>31300257</ClientID>
<AuthenticationCodeMac>
<IterationCount>512</IterationCount>
<Mac>4bRJf9xXd3KchKoTenHJiw==</Mac>
</AuthenticationCodeMac>
</AuthenticationData>
</dskpp:KeyProvClientHello>
In this example, the server responds to the previous request using
the key wrap profile.
<?xml version="1.0" encoding="UTF-8"?>
<dskpp:KeyProvServerFinished Version="1.0" Status="Success"
xmlns:dskpp="urn:ietf:params:xml:ns:keyprov:1.0:protocol"
xmlns:pskc="urn:ietf:params:xml:ns:keyprov:1.0:container"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:ds="http://www.w3.org/2000/09/xmldsig#"
xmlns:xenc="http://www.w3.org/2001/04/xmlenc#"
xsi:schemaLocation="urn:ietf:params:xml:ns:keyprov:1.0:protocol
keyprov-dskpp-1.0.xsd">
<KeyContainer>
<ServerID>https://www.somedskppservice.com/</ServerID>
<KeyContainer Version="1.0">
<EncryptionMethod Algorithm="http://www.w3.org/2001/04/xmlenc#kw-aes128"
xmlns="urn:ietf:params:xml:ns:keyprov:1.0:container">
<KeyInfo>
<ds:KeyName>Key-001</ds:KeyName>
</KeyInfo>
</EncryptionMethod>
<pskc:DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#hmac-sha1"/>
<Device xmlns="urn:ietf:params:xml:ns:keyprov:1.0:container">
<Key KeyAlgorithm="urn:ietf:params:xml:schema:keyprov:otpalg#HOTP"
KeyId="SDU312345678">
<Issuer>CredentialIssuer</Issuer>
<Usage otp="true">
<ResponseFormat format="DECIMAL" length="6"/>
</Usage>
<FriendlyName>MyFirstToken</FriendlyName>
<Data Name="SECRET">
<Value>
JSPUyp3azOkqJENSsh6b2hdXz1WBYypzJxEr+ikQAa22M6V/BgZhRg==
</Value>
<ValueDigest>
i8j+kpbfKQsSlwmJYS99lQ==
</ValueDigest>
</Data>
<Data Name="COUNTER">
<Value>AAAAAAAAAAA=</Value>
</Data>
<Expiry>10/30/2012</Expiry>
</Key>
</Device>
</KeyContainer>
</KeyContainer>
<Mac MacAlgorithm="urn:ietf:params:xml:schema:keyprov:protocol#dskpp-prf-aes">
miidfasde312asder394jw==
</Mac>
<AuthenticationData>
<AuthenticationCodeMac>
<Mac>4bRJf9xXd3KchKoTenHJiw==</Mac>
</AuthenticationCodeMac>
</AuthenticationData>
</dskpp:KeyProvServerFinished>
7.2.1.3. Example Using the Passphrase-Based Key Wrap Profile
The client sends a request similar to that in Section 7.2.1.1 with
authentication data basing on an authentication code, and the server
responds using the Passphrase-Based Key Wrap Profile. The
authentication data is set in clear text when it is sent over a
secure transport channel such as TLS.
<?xml version="1.0" encoding="UTF-8"?>
<dskpp:KeyProvClientHello Version="1.0"
xmlns:dskpp="urn:ietf:params:xml:ns:keyprov:1.0:protocol"
xmlns:pskc="urn:ietf:params:xml:ns:keyprov:1.0:container"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:ds="http://www.w3.org/2000/09/xmldsig#"
xmlns:pkcs-5="http://www.rsasecurity.com/rsalabs/pkcs/schemas/pkcs-5v2-0#"
xsi:schemaLocation="urn:ietf:params:xml:ns:keyprov:1.0:protocol
keyprov-dskpp-1.0.xsd">
<DeviceIdentifierData>
<DeviceId>
<pskc:Manufacturer>ManufacturerABC</pskc:Manufacturer>
<pskc:SerialNo>XL0000000001234</pskc:SerialNo>
<pskc:Model>U2</pskc:Model>
</DeviceId>
</DeviceIdentifierData>
<ClientNonce>xwQzwEl0CjPAiQeDxwRJdQ==</ClientNonce>
<SupportedKeyTypes>
<Algorithm>urn:ietf:params:xml:schema:keyprov:otpalg#HOTP</Algorithm>
<Algorithm>
http://www.rsa.com/rsalabs/otps/schemas/2005/09/otps-wst#SecurID-AES
</Algorithm>
</SupportedKeyTypes>
<SupportedEncryptionAlgorithms>
<Algorithm>http://www.w3.org/2001/05/xmlenc#rsa_1_5</Algorithm>
<Algorithm>http://www.w3.org/2001/04/xmlenc#kw-aes128</Algorithm>
<Algorithm>
http://www.rsasecurity.com/rsalabs/pkcs/schemas/pkcs-5#pbes2
</Algorithm>
<Algorithm>
urn:ietf:params:xml:schema:keyprov:protocol#dskpp-prf-aes
</Algorithm>
</SupportedEncryptionAlgorithms>
<SupportedMacAlgorithms>
<Algorithm>
urn:ietf:params:xml:schema:keyprov:protocol#dskpp-prf-aes
</Algorithm>
</SupportedMacAlgorithms>
<SupportedProtocolVariants>
<TwoPass>
<SupportedKeyInitializationMethod>
urn:ietf:params:xml:schema:keyprov:protocol#wrap
</SupportedKeyInitializationMethod>
<Payload xsi:type="ds:KeyInfoType">
<ds:KeyName>Key_001</ds:KeyName>
</Payload>
<SupportedKeyInitializationMethod>
urn:ietf:params:xml:schema:keyprov:protocol#passphrase-wrap
</SupportedKeyInitializationMethod>
</TwoPass>
</SupportedProtocolVariants>
<SupportedKeyContainers>
<KeyContainerFormat>
urn:ietf:params:xml:schema:keyprov:container#KeyContainer
</KeyContainerFormat>
</SupportedKeyContainers>
<AuthenticationData>
<ClientID>31300257</ClientID>
<AuthenticationCodeMac>
<IterationCount>512</IterationCount>
<Mac>4bRJf9xXd3KchKoTenHJiw==</Mac>
</AuthenticationCodeMac>
</AuthenticationData>
</dskpp:KeyProvClientHello>
In this example, the server responds to the previous request using
the Passphrase-Based Key Wrap Profile.
<?xml version="1.0" encoding="UTF-8"?>
<dskpp:KeyProvServerFinished Version="1.0" SessionID="4114" Status="Success"
xmlns:dskpp="urn:ietf:params:xml:ns:keyprov:1.0:protocol"
xmlns:pskc="urn:ietf:params:xml:ns:keyprov:1.0:container"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:ds="http://www.w3.org/2000/09/xmldsig#"
xmlns:xenc="http://www.w3.org/2001/04/xmlenc#"
xsi:schemaLocation="urn:ietf:params:xml:ns:keyprov:1.0:protocol
keyprov-dskpp-1.0.xsd">
<KeyContainer>
<KeyContainer Version="1.0">
<EncryptionMethod
Algorithm="http://www.rsasecurity.com/rsalabs/pkcs/schemas/pkcs-5#pbes2"
xmlns="urn:ietf:params:xml:ns:keyprov:1.0:container">
<PBEEncryptionParam
EncryptionAlgorithm="http://www.w3.org/2001/04/xmlenc#kw-aes128-cbc">
<PBESalt>y6TzckeLRQw=</PBESalt>
<PBEIterationCount>1024</PBEIterationCount>
</PBEEncryptionParam>
<IV>c2FtcGxlaXY=</IV>
</EncryptionMethod>
<pskc:DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#hmac-sha1"/>
<Device xmlns="urn:ietf:params:xml:ns:keyprov:1.0:container">
<Key KeyAlgorithm="urn:ietf:params:xml:schema:keyprov:otpalg#HOTP"
KeyId="SDU312345678">
<Issuer>CredentialIssuer</Issuer>
<Usage otp="true">
<ResponseFormat format="DECIMAL" length="6"/>
</Usage>
<FriendlyName>MyFirstToken</FriendlyName>
<Data Name="SECRET">
<Value>
JSPUyp3azOkqJENSsh6b2hdXz1WBYypzJxEr+ikQAa22M6V/BgZhRg==
</Value>
<ValueDigest>
i8j+kpbfKQsSlwmJYS99lQ==
</ValueDigest>
</Data>
<Data Name="COUNTER">
<Value>AAAAAAAAAAA=</Value>
</Data>
<Expiry>10/30/2012</Expiry>
</Key>
</Device>
</KeyContainer>
</KeyContainer>
<Mac MacAlgorithm="urn:ietf:params:xml:schema:keyprov:protocol#dskpp-prf-aes">
miidfasde312asder394jw==
</Mac>
<AuthenticationData>
<AuthenticationCodeMac>
<Mac>4bRJf9xXd3KchKoTenHJiw==</Mac>
</AuthenticationCodeMac>
</AuthenticationData>
</dskpp:KeyProvServerFinished>
7.2.2. Components of the <KeyProvClientHello> Request
The components of this message have the following meaning: The components of this message have the following meaning:
o Version: (attribute inherited from the AbstractRequestType type)
The highest version of this protocol the client supports. Only
version one ("1.0") is currently specified.
o <DeviceIdentifierData>: An identifier for the cryptographic module
as defined in Section 5.3 above. The identifier MUST only be
present if such shared secrets exist or if the identifier was
provided by the server in a <KeyProvTrigger> element (see
Section 12.2.7 below). In the latter case, it MUST have the same
value as the identifier provided in that element.
o <KeyID>: An identifier for the key that will be overwritten if the
protocol run is successful. The identifier MUST only be present
if the key exists or the identifier was provided by the server in
a <KeyProvTrigger> element (see Section 12.2.7 below). In the
latter case, it MUST have the same value as the identifier
provided in that element.
o <KeyProvClientNonce>: This is the nonce R, which, when present,
MUST be used by the server when calculating MAC values (see
below). It is RECOMMENDED that clients include this element
whenever the <KeyID> element is present.
o <TriggerNonce>: This OPTIONAL element MUST be present if and only
if the DSKPP run was initialized with a <KeyProvTrigger> message
(see Section 12.2.7 below), and MUST, in that case, have the same
value as the <TriggerNonce> child of that message. A server using
nonces in this way MUST verify that the nonce is valid and that
any device or key identifier values provided in the
<KeyProvTrigger> message match the corresponding identifier values
in the <KeyProvClientHello> message.
o <SupportedKeyTypes>: A sequence of URIs indicating the key types
for which the cryptographic module is willing to generate keys
through DSKPP.
o <SupportedEncryptionAlgorithms>: A sequence of URIs indicating the
encryption algorithms supported by the cryptographic module for
the purposes of DSKPP. The DSKPP client MAY indicate the same
algorithm both as a supported key type and as an encryption
algorithm.
o <SupportedMacAlgorithms>: A sequence of URIs indicating the MAC
algorithms supported by the cryptographic module for the purposes
of DSKPP. The DSKPP client MAY indicate the same algorithm both
as an encryption algorithm and as a MAC algorithm (e.g.,
urn:ietf:params:xml:schema:keyprov:protocol#dskpp-prf-aes defined
in Appendix B).
o <SupportedProtocolVariants>: This OPTIONAL element is used by the
DSKPP client to indicate support for four-pass or two-pass DSKPP.
If two-pass support is specified, then <KeyProvClientNonce> MUST
be set to nonce R in the <KeyProvClientHello> message unless
<TriggerNonce> is already present.
o <SupportedKeyContainers>: This OPTIONAL element is a sequence of
URIs indicating the key container formats supported by the DSKPP
client. If this element is not provided, then the DSKPP server
MUST proceed with
"urn:ietf:params:xml:schema:keyprov:container#KeyContainer" (see
[PSKC].
o <AuthenticationData>: This OPTIONAL element contains data that the
DSKPP client uses to authenticate the user or device to the DSKPP
server. The element is set as specified in Section 5.3.
o <Extensions>: A sequence of extensions. One extension is defined
for this message in this version of DSKPP: the ClientInfoType (see
Section 10).
7.2.3. Components of a <KeyProvServerFinished> Response
This message is the last message of the DSKPP protocol run. In a
4-pass exchange, the DSKPP server sends this message in response to a
<KeyProvClientNonce> message, whereas in a 2-pass exchange, the DSKPP
server sends this message in response to a <KeyProvClientHello>
message. In a 1-pass exchange, the DSKPP server sends only this
message to the client. The components of this message have the
following meaning:
o Version: (inherited from the AbstractResponseType type) The DSKPP o Version: (inherited from the AbstractResponseType type) The DSKPP
version used in this session. version used in this session.
o SessionID: (inherited from the AbstractResponseType type) The o SessionID: (inherited from the AbstractResponseType type) The
previously established identifier for this session. previously established identifier for this session.
o Status: (inherited from the AbstractResponseType type) Return code o Status: (inherited from the AbstractResponseType type) Return code
for the <KeyProvServerFinished> message. If Status is not for the <KeyProvServerFinished> message. If Status is not
"Success", only the Status, SessionID, and Version attributes will "Success", only the Status, SessionID, and Version attributes will
be present (the presence of the SessionID attribute is dependent be present (the presence of the SessionID attribute is dependent
on the type of reported error); otherwise, all the other elements on the type of reported error); otherwise, all the other elements
MUST be present as well. In this latter case, the MUST be present as well. In this latter case, the
<KeyProvServerFinished> message can be seen as a "Commit" message, <KeyProvServerFinished> message can be seen as a "Commit" message,
instructing the cryptographic module to store the generated key instructing the cryptographic module to store the generated key
and associate the given key identifier with this key. and associate the given key identifier with this key.
o <KeyContainer>: The key container containing symmetric key values o <KeyContainer>: The key container containing symmetric key values
(in the case of a 2- or 1-pass exchange) and configuration data. (in the case of a 2-pass exchange) and configuration data. The
The default container format is based on the KeyContainerType type default container format is based on the KeyContainerType type
from PSKC, as defined in [PSKC]. from PSKC, as defined in [PSKC].
o <Extensions>: A list of extensions chosen by the DSKPP server. o <Extensions>: A list of extensions chosen by the DSKPP server.
For this message, this version of DSKPP defines one extension, the For this message, this version of DSKPP defines one extension, the
ClientInfoType (see Section 10). ClientInfoType (see Section 5).
o <Mac>: To avoid a false "Commit" message causing the cryptographic o <Mac>: To avoid a false "Commit" message causing the cryptographic
module to end up in an initialized state for which the server does module to end up in an initialized state for which the server does
not know the stored key, <KeyProvServerFinished> messages MUST not know the stored key, <KeyProvServerFinished> messages MUST
always be authenticated with a MAC. The MAC MUST be made using always be authenticated with a MAC. The MAC MUST be made using
the already established MAC algorithm. the already established MAC algorithm.
o <AuthenticationData>: This OPTIONAL element contains data that
allows the DSKPP client to authenticate the DSKPP server. The MAC
value is calculated with K_MAC' as specified in Section 4.4.3.
When receiving a <KeyProvServerFinished> message with
Status="Success" for which the MAC verifies, the DSKPP client MUST
associate the generated key K_TOKEN with the provided key
identifier and store this data permanently. After this operation,
it MUST not be possible to overwrite the key unless knowledge of
an authorizing key is proven through a MAC on a later
<KeyProvServerHello> (and <KeyProvServerFinished>) message.
The DSKPP client MUST verify the MAC. The DSKPP client MUST
terminate the DSKPP session if the MAC does not verify, and MUST,
in this case, also delete any nonces, keys, and/or secrets
associated with the failed run of the DSKPP protocol.
The MacType's MacAlgorithm attribute MUST, when present, identify
the negotiated MAC algorithm.
7.3. DSKPP Server Results: The StatusCode Type 4.7. The StatusCode Type
The StatusCode type enumerates all possible return codes. Upon The StatusCode type enumerates all possible return codes:
transmission or receipt of a message for which the Status attribute's
value is not "Success" or "Continue", the default behavior, unless <xs:simpleType name="StatusCode">
explicitly stated otherwise below, is that both the DSKPP server and <xs:restriction base="xs:string">
the DSKPP client MUST immediately terminate the DSKPP session. DSKPP <xs:enumeration value="Continue" />
servers and DSKPP clients MUST delete any secret values generated as <xs:enumeration value="Success" />
a result of failed runs of the DSKPP protocol. Session identifiers <xs:enumeration value="Abort" />
MAY be retained from successful or failed protocol runs for replay <xs:enumeration value="AccessDenied" />
detection purposes, but such retained identifiers MUST not be reused <xs:enumeration value="MalformedRequest" />
for subsequent runs of the protocol. <xs:enumeration value="UnknownRequest" />
<xs:enumeration value="UnknownCriticalExtension" />
<xs:enumeration value="UnsupportedVersion" />
<xs:enumeration value="NoSupportedKeyTypes" />
<xs:enumeration value="NoSupportedEncryptionAlgorithms" />
<xs:enumeration value="NoSupportedMacAlgorithms" />
<xs:enumeration value="NoProtocolVariants" />
<xs:enumeration value="NoSupportedKeyContainers" />
<xs:enumeration value="AuthenticationDataMissing" />
<xs:enumeration value="AuthenticationDataInvalid" />
<xs:enumeration value="InitializationFailed" />
</xs:restriction>
</xs:simpleType>
Upon transmission or receipt of a message for which the Status
attribute's value is not "Success" or "Continue", the default
behavior, unless explicitly stated otherwise below, is that both the
DSKPP server and the DSKPP client MUST immediately terminate the
DSKPP session. DSKPP servers and DSKPP clients MUST delete any
secret values generated as a result of failed runs of the DSKPP
protocol. Session identifiers MAY be retained from successful or
failed protocol runs for replay detection purposes, but such retained
identifiers MUST NOT be reused for subsequent runs of the protocol.
When possible, the DSKPP client SHOULD present an appropriate error When possible, the DSKPP client SHOULD present an appropriate error
message to the user. message to the user.
These status codes are valid in all DSKPP Response messages unless These status codes are valid in all DSKPP Response messages unless
explicitly stated otherwise: explicitly stated otherwise:
o "Continue" indicates that the DSKPP server is ready for a o "Continue" indicates that the DSKPP server is ready for a
subsequent request from the DSKPP client. It cannot be sent in subsequent request from the DSKPP client. It cannot be sent in
the server's final message. the server's final message.
o "Success" indicates successful completion of the DSKPP session. o "Success" indicates successful completion of the DSKPP session.
It can only be sent in the server's final message. It can only be sent in the server's final message.
o "Abort" indicates that the DSKPP server rejected the DSKPP o "Abort" indicates that the DSKPP server rejected the DSKPP
client's request for unspecified reasons. client's request for unspecified reasons.
o "AccessDenied" indicates that the DSKPP client is not authorized o "AccessDenied" indicates that the DSKPP client is not authorized
to contact this DSKPP server. to contact this DSKPP server.
o "MalformedRequest" indicates that the DSKPP server failed to parse o "MalformedRequest" indicates that the DSKPP server failed to parse
the DSKPP client's request. the DSKPP client's request.
o "UnknownRequest" indicates that the DSKPP client made a request o "UnknownRequest" indicates that the DSKPP client made a request
that is unknown to the DSKPP server. that is unknown to the DSKPP server.
o "UnknownCriticalExtension" indicates that a critical DSKPP o "UnknownCriticalExtension" indicates that a critical DSKPP
extension (see below) used by the DSKPP client was not supported extension (see below) used by the DSKPP client was not supported
skipping to change at page 62, line 49 skipping to change at page 49, line 26
o "UnsupportedVersion" indicates that the DSKPP client used a DSKPP o "UnsupportedVersion" indicates that the DSKPP client used a DSKPP
protocol version not supported by the DSKPP server. This error is protocol version not supported by the DSKPP server. This error is
only valid in the DSKPP server's first response message. only valid in the DSKPP server's first response message.
o "NoSupportedKeyTypes" indicates that the DSKPP client only o "NoSupportedKeyTypes" indicates that the DSKPP client only
suggested key types that are not supported by the DSKPP server. suggested key types that are not supported by the DSKPP server.
This error is only valid in the DSKPP server's first response This error is only valid in the DSKPP server's first response
message. message.
o "NoSupportedEncryptionAlgorithms" indicates that the DSKPP client o "NoSupportedEncryptionAlgorithms" indicates that the DSKPP client
only suggested encryption algorithms that are not supported by the only suggested encryption algorithms that are not supported by the
DSKPP server. This error is only valid in the DSKPP server's DSKPP server. This error is only valid in the DSKPP server's
first response message. Note that the error will only occur if first response message.
the DSKPP server does not support any of the DSKPP client's
suggested encryption algorithms.
o "NoSupportedMacAlgorithms" indicates that the DSKPP client only o "NoSupportedMacAlgorithms" indicates that the DSKPP client only
suggested MAC algorithms that are not supported by the DSKPP suggested MAC algorithms that are not supported by the DSKPP
server. This error is only valid in the DSKPP server's first server. This error is only valid in the DSKPP server's first
response message. Note that the error will only occur if the response message.
DSKPP server does not support any of the DSKPP client's suggested
MAC algorithms.
o "NoProtocolVariants" indicates that the DSKPP client only o "NoProtocolVariants" indicates that the DSKPP client only
suggested a protocol variant (either 2-pass or 4-pass) that is not suggested a protocol variation (either 2-pass or 4-pass) that is
supported by the DSKPP server. This error is only valid in the not supported by the DSKPP server. This error is only valid in
DSKPP server's first response message. Note that the error will the DSKPP server's first response message.
only occur if the DSKPP server does not support any of the DSKPP
client's suggested protocol variants.
o "NoSupportedKeyContainers" indicates that the DSKPP client only o "NoSupportedKeyContainers" indicates that the DSKPP client only
suggested key container formats that are not supported by the suggested key container formats that are not supported by the
DSKPP server. This error is only valid in the DSKPP server's DSKPP server. This error is only valid in the DSKPP server's
first response message. Note that the error will only occur if first response message.
the DSKPP server does not support any of the DSKPP client's
suggested key container formats.
o "AuthenticationDataMissing" indicates that the DSKPP client didn't o "AuthenticationDataMissing" indicates that the DSKPP client didn't
provide authentication data that the DSKPP server required. provide authentication data that the DSKPP server required.
o "AuthenticationDataInvalid" indicates that the DSKPP client o "AuthenticationDataInvalid" indicates that the DSKPP client
supplied user or device authentication data that the DSKPP server supplied user authentication data that the DSKPP server failed to
failed to validate. validate.
o "InitializationFailed" indicates that the DSKPP server could not o "InitializationFailed" indicates that the DSKPP server could not
generate a valid key given the provided data. When this status generate a valid key given the provided data. When this status
code is received, the DSKPP client SHOULD try to restart DSKPP, as code is received, the DSKPP client SHOULD try to restart DSKPP, as
it is possible that a new run will succeed. it is possible that a new run will succeed.
o "ProvisioningPeriodExpired" indicates that the provisioning period o "ProvisioningPeriodExpired" indicates that the provisioning period
set by the DSKPP server has expired. When the status code is set by the DSKPP server has expired. When the status code is
received, the DSKPP client SHOULD report the key initialization received, the DSKPP client SHOULD report the reason for key
failure reason to the user and the user MUST register with the initialization failure to the user and the user MUST register with
DSKPP server to initialize a new key. the DSKPP server to initialize a new key.
8. One-Pass Protocol
In this section, example messages are used to describe parameters,
encoding and semantics in a 1-pass DSKPP protocol. The examples are
written using XML. While they are syntactically correct, MAC and
cipher values are fictitious.
8.1. XML Basics
The DSKPP XML schema can be found in Section 13. Some DSKPP elements
rely on the parties being able to compare received values with stored
values. Unless otherwise noted, all elements in this document that
have the XML Schema "xs:string" type, or a type derived from it, MUST
be compared using an exact binary comparison. In particular, DSKPP
implementations MUST NOT depend on case-insensitive string
comparisons, normalization or trimming of white space, or conversion
of locale-specific formats such as numbers.
Implementations that compare values that are represented using
different character encodings MUST use a comparison method that
returns the same result as converting both values to the Unicode
character encoding, Normalization Form C [UNICODE], and then
performing an exact binary comparison.
No collation or sorting order for attributes or element values is
defined. Therefore, DSKPP implementations MUST NOT depend on
specific sorting orders for values.
8.2. Server to Client Only: <KeyProvServerFinished>
8.2.1. Example
The Server sends a provisioned key to a client with prior knowledge
about the client's capabilities:
<?xml version="1.0" encoding="UTF-8"?>
<dskpp:KeyProvServerFinished Version="1.0" SessionID="4114" Status="Success"
xmlns:dskpp="urn:ietf:params:xml:ns:keyprov:1.0:protocol"
xmlns:pskc="urn:ietf:params:xml:ns:keyprov:1.0:container"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:ds="http://www.w3.org/2000/09/xmldsig#"
xmlns:xenc="http://www.w3.org/2001/04/xmlenc#"
xsi:schemaLocation="urn:ietf:params:xml:ns:keyprov:1.0:protocol
keyprov-dskpp-1.0.xsd">
<KeyContainer>
<KeyContainer Version="1.0">
<pskc:EncryptionMethod
Algorithm="http://www.w3.org/2001/05/xmlenc#rsa_1_5">
<pskc:KeyInfo>
<ds:X509Data>
<ds:X509Certificate>miib</ds:X509Certificate>
</ds:X509Data>
</pskc:KeyInfo>
</pskc:EncryptionMethod>
<pskc:DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#hmac-sha1"/>
<Device xmlns="urn:ietf:params:xml:ns:keyprov:1.0:container">
<Key KeyAlgorithm="urn:ietf:params:xml:schema:keyprov:otpalg#HOTP"
KeyId="SDU312345678">
<Issuer>CredentialIssuer</Issuer>
<Usage otp="true">
<ResponseFormat format="DECIMAL" length="6"/>
</Usage>
<FriendlyName>MyFirstToken</FriendlyName>
<Data Name="SECRET">
<Value>
7JHUyp3azOkqJENSsh6b2vxXzwGBYypzJxEr+ikQAa229KV/BgZhGA==
</Value>
<ValueDigest>
i8j+kpbfKQsSlwmJYS99lQ==
</ValueDigest>
</Data>
<Data Name="COUNTER">
<Value>AAAAAAAAAAA=</Value>
</Data>
<Expiry>10/30/2009</Expiry>
</Key>
</Device>
</KeyContainer>
</KeyContainer>
<Mac MacAlgorithm="urn:ietf:params:xml:schema:keyprov:protocol#dskpp-prf-aes">
miidfasde312asder394jw==
</Mac>
<AuthenticationData>
<AuthenticationCodeMac>
<Mac>4bRJf9xXd3KchKoTenHJiw==</Mac>
</AuthenticationCodeMac>
</AuthenticationData>
</dskpp:KeyProvServerFinished>
8.2.2. Components of a <KeyProvServerFinished> Response
This message is the last message of the DSKPP protocol run. In a
4-pass exchange, the DSKPP server sends this message in response to a
<KeyProvClientNonce> message, whereas in a 2-pass exchange, the DSKPP
server sends this message in response to a <KeyProvClientHello>
message. In a 1-pass exchange, the DSKPP server sends only this
message to the client. The components of this message have the
following meaning:
o Version: (inherited from the AbstractResponseType type) The DSKPP
version used in this session.
o SessionID: (inherited from the AbstractResponseType type) The
previously established identifier for this session.
o Status: (inherited from the AbstractResponseType type) Return code
for the <KeyProvServerFinished> message. If Status is not
"Success", only the Status, SessionID, and Version attributes will
be present (the presence of the SessionID attribute is dependent
on the type of reported error); otherwise, all the other elements
MUST be present as well. In this latter case, the
<KeyProvServerFinished> message can be seen as a "Commit" message,
instructing the cryptographic module to store the generated key
and associate the given key identifier with this key.
o <KeyContainer>: The key container containing symmetric key values
(in the case of a 2- or 1-pass exchange) and configuration data.
The default container format is based on the KeyContainerType type
from PSKC, as defined in [PSKC].
o <Extensions>: A list of extensions chosen by the DSKPP server.
For this message, this version of DSKPP defines one extension, the
ClientInfoType (see Section 10).
o <Mac>: To avoid a false "Commit" message causing the cryptographic
module to end up in an initialized state for which the server does
not know the stored key, <KeyProvServerFinished> messages MUST
always be authenticated with a MAC. The MAC MUST be made using
the already established MAC algorithm.
o <AuthenticationData>: This OPTIONAL element contains data that
allows the DSKPP client to authenticate the DSKPP server. The MAC
value is calculated with K_MAC' as specified in Section 4.5.3.
When receiving a <KeyProvServerFinished> message with
Status="Success" for which the MAC verifies, the DSKPP client MUST
associate the generated key K_TOKEN with the provided key
identifier and store this data permanently. After this operation,
it MUST not be possible to overwrite the key unless knowledge of
an authorizing key is proven through a MAC on a later
<KeyProvServerHello> (and <KeyProvServerFinished>) message.
The DSKPP client MUST verify the MAC. The DSKPP client MUST
terminate the DSKPP session if the MAC does not verify, and MUST,
in this case, also delete any nonces, keys, and/or secrets
associated with the failed run of the DSKPP protocol.
The MacType's MacAlgorithm attribute MUST, when present, identify
the negotiated MAC algorithm.
9. Trigger
In this section, an example is used to describe parameters, encoding
and semantics in a DSKPP Trigger message. The example is written
using XML.
9.1. XML Basics
The DSKPP XML schema can be found in Section 13. Some DSKPP elements
rely on the parties being able to compare received values with stored
values. Unless otherwise noted, all elements in this document that
have the XML Schema "xs:string" type, or a type derived from it, MUST
be compared using an exact binary comparison. In particular, DSKPP
implementations MUST NOT depend on case-insensitive string
comparisons, normalization or trimming of white space, or conversion
of locale-specific formats such as numbers.
Implementations that compare values that are represented using
different character encodings MUST use a comparison method that
returns the same result as converting both values to the Unicode
character encoding, Normalization Form C [UNICODE], and then
performing an exact binary comparison.
No collation or sorting order for attributes or element values is
defined. Therefore, DSKPP implementations MUST NOT depend on
specific sorting orders for values.
9.2. Example
<dskpp:KeyProvTrigger Version="1.0"
xmlns:dskpp="urn:ietf:params:xml:ns:keyprov:1.0:protocol"
xmlns:pskc="urn:ietf:params:xml:ns:keyprov:1.0:container"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="urn:ietf:params:xml:ns:keyprov:1.0:protocol
keyprov-dskpp-1.0.xsd">
<InitializationTrigger>
<DeviceIdentifierData>
<DeviceId>
<pskc:Manufacturer>ManufacturerABC</pskc:Manufacturer>
<pskc:SerialNo>XL0000000001234</pskc:SerialNo>
<pskc:Model>U2</pskc:Model>
</DeviceId>
</DeviceIdentifierData>
<KeyID>SE9UUDAwMDAwMDAx</KeyID>
<TokenPlatformInfo KeyLocation="Hardware" AlgorithmLocation="Software"/>
<TriggerNonce>112dsdfwf312asder394jw==</TriggerNonce>
<DSKPPServerUrl>https://www.somekeyprovservice.com/</DSKPPServerUrl>
</InitializationTrigger>
</dskpp:KeyProvTrigger>
9.3. Components of the <KeyProvTrigger> Message
The DSKPP server MAY initialize the DSKPP protocol by sending a
<KeyProvTrigger> message. This message MAY, e.g., be sent in
response to a user requesting key initialization in a browsing
session.
The <KeyProvTrigger> element is intended for the DSKPP client and MAY
inform the DSKPP client about the identifier for the device that
houses the cryptographic module to be initialized, and optionally of
the identifier for the key on that module. The latter would apply to
key renewal. The trigger always contains a nonce to allow the DSKPP
server to couple the trigger with a later DSKPP <KeyProvClientHello>
request. Finally, the trigger MAY contain a URL to use when
contacting the DSKPP server. The <xs:any> elements are for future
extensibility. Any provided <DeviceIdentifierData> or <KeyID> values
MUST be used by the DSKPP client in the subsequent
<KeyProvClientHello> request. The OPTIONAL <TokenPlatformInfo>
element informs the DSKPP client about the characteristics of the
intended cryptographic module platform, and applies in the public-key
variant of DSKPP in situations when the client potentially needs to
decide which one of several modules to initialize.
10. Extensibility 5. Extensibility
10.1. The ClientInfoType Type 5.1. The ClientInfoType Type
present in a <KeyProvClientHello> or a <KeyProvClientNonce> message, Present in a <KeyProvClientHello> or a <KeyProvClientNonce> message,
the OPTIONAL ClientInfoType extension contains DSKPP client-specific the OPTIONAL ClientInfoType extension contains DSKPP client-specific
information. DSKPP servers MUST support this extension. DSKPP information. DSKPP servers MUST support this extension. DSKPP
servers MUST NOT attempt to interpret the data it carries and, if servers MUST NOT attempt to interpret the data it carries and, if
received, MUST include it unmodified in the current protocol run's received, MUST include it unmodified in the current protocol run's
next server response. Servers need not retain the ClientInfoType's next server response. Servers need not retain the ClientInfoType's
data after that response has been generated. data after that response has been generated.
10.2. The ServerInfoType Type 5.2. The ServerInfoType Type
When present, the OPTIONAL ServerInfoType extension contains DSKPP When present, the OPTIONAL ServerInfoType extension contains DSKPP
server-specific information. This extension is only valid in server-specific information. This extension is only valid in
<KeyProvServerHello> messages for which Status = "Continue". DSKPP <KeyProvServerHello> messages for which Status = "Continue". DSKPP
clients MUST support this extension. DSKPP clients MUST NOT attempt clients MUST support this extension. DSKPP clients MUST NOT attempt
to interpret the data it carries and, if received, MUST include it to interpret the data it carries and, if received, MUST include it
unmodified in the current protocol run's next client request (i.e., unmodified in the current protocol run's next client request (i.e.,
the <KeyProvClientNonce> message). DSKPP clients need not retain the the <KeyProvClientNonce> message). DSKPP clients need not retain the
ServerInfoType's data after that request has been generated. This ServerInfoType's data after that request has been generated. This
extension MAY be used, e.g., for state management in the DSKPP extension MAY be used, e.g., for state management in the DSKPP
server. server.
10.3. The KeyInitializationDataType Type 6. Protocol Bindings
This extension is used for 2- and 1-pass DSKPP exchange; it carries
an identifier for the selected key initialization method as well as
key initialization method-dependent payload data.
Servers MAY include this extension in a <KeyProvServerFinished>
message that is being sent in response to a received
<KeyProvClientHello> message if and only if that <KeyProvClientHello>
message selected TwoPassSupport as the ProtocolVariantType and the
client indicated support for the selected key initialization method.
Servers MUST include this extension in a <KeyProvServerFinished>
message that is sent as part of a 1-pass DSKPP.
The elements of this type have the following meaning:
o <KeyInitializationMethod>: A two-pass key initialization method
supported by the DSKPP client.
o <Payload>: A payload associated with the key initialization
method. Since the syntax is a shorthand for <xs:element
name="Payload" type="xs:anyType"/>, any well-formed payloads can
be carried in this element.
11. Key Initialization Profiles of Two- and One-Pass DSKPP
11.1. Introduction
This appendix introduces three profiles of DSKPP for key
initialization. They MAY all be used for two- as well as one-pass
initialization of cryptographic modules. Further profiles MAY be
defined by external entities or through the IETF process.
11.2. Key Transport Profile
11.2.1. Introduction
This profile initializes the cryptographic module with a symmetric
key, K_TOKEN, through key transport and key derivation. The key
transport is carried out using a public key, K_CLIENT, whose private
key part resides in the cryptographic module as the transport key. A
key K from which two keys, K_TOKEN and K_MAC are derived MUST be
transported.
11.2.2. Identification
This profile MUST be identified with the following URN:
urn:ietf:params:xml:schema:keyprov:protocol#transport
11.2.3. Payloads
In the two-pass version of DSKPP, the client MUST send a payload
associated with this key initialization method. The payload MUST be
of type ds:KeyInfoType ([XMLDSIG]), and only those choices of the ds:
KeyInfoType that identify a public key are allowed. The ds:
X509Certificate option of the ds:X509Data alternative is RECOMMENDED
when the public key corresponding to the private key on the
cryptographic module has been certified.
The server payload associated with this key initialization method
MUST be of type xenc:EncryptedKeyType ([XMLENC]), and only those
encryption methods utilizing a public key that are supported by the
DSKPP client (as indicated in the <SupportedEncryptionAlgorithms>
element of the <KeyProvClientHello> message in the case of 2-pass
DSKPP, or as otherwise known in the case of 1-pass DSKPP) are allowed
as values for the <xenc:EncryptionMethod> element. Further, in the
case of 2-pass DSKPP, the <ds:KeyInfo> element MUST contain the same
value (i.e. identify the same public key) as the <Payload> of the
corresponding supported key initialization method in the
<KeyProvClientHello> message that triggered the response. The
<CarriedKeyName> element MAY be present, but MUST, when present,
contain the same value as the <KeyID> element of the
<KeyProvServerFinished> message. The Type attribute of the xenc:
EncryptedKeyType MUST be present and MUST identify the type of the
wrapped key. The type MUST be one of the types supported by the
DSKPP client (as reported in the <SupportedKeyTypes> of the preceding
<KeyProvClientHello> message in the case of 2-pass DSKPP, or as
otherwise known in the case of 1-pass DSKPP). The transported key
MUST consist of two parts of equal length. The first half
constitutes K_MAC and the second half constitutes K_TOKEN. The
length of K_TOKEN (and hence also the length of K_MAC) is determined
by the type of K_TOKEN.
DSKPP servers and cryptographic modules supporting this profile MUST
support the http://www.w3.org/2001/04/xmlenc#rsa-1_5 key-wrapping
mechanism defined in [XMLENC].
When this profile is used, the MacAlgorithm attribute of the <Mac>
element of the <KeyProvServerFinished> message MUST be present and
MUST identify the selected MAC algorithm. The selected MAC algorithm
MUST be one of the MAC algorithms supported by the DSKPP client (as
indicated in the <SupportedMacAlgorithms> element of the
<KeyProvClientHello> message in the case of 2-pass DSKPP, or as
otherwise known in the case of 1-pass DSKPP). The MAC MUST be
calculated as described in Section 4.4 for Two-Pass DSKPP and
Section 4.5 for One-Pass DSKPP.
In addition, DSKPP servers MUST include the AuthenticationDataType
element in their <KeyProvServerFinished> messages whenever a
successful protocol run will result in an existing K_TOKEN being
replaced.
11.3. Key Wrap Profile
11.3.1. Introduction
This profile initializes the cryptographic module with a symmetric
key, K_TOKEN, through key wrap and key derivation. The key wrap MUST
be carried out using a (symmetric) key-wrapping key, K_SHARED, known
in advance by both the cryptographic module and the DSKPP server. A
key K from which two keys, K_TOKEN and K_MAC are derived MUST be
wrapped.
11.3.2. Identification
This profile MUST be identified with the following URI:
urn:ietf:params:xml:schema:keyprov:protocol#wrap
11.3.3. Payloads
In the 2-pass version of DSKPP, the client MUST send a payload
associated with this key initialization method. The payload MUST be
of type ds:KeyInfoType ([XMLDSIG]), and only those choices of the ds:
KeyInfoType that identify a symmetric key are allowed. The ds:
KeyName alternative is RECOMMENDED.
The server payload associated with this key initialization method
MUST be of type xenc:EncryptedKeyType ([XMLENC]), and only those
encryption methods utilizing a symmetric key that are supported by
the DSKPP client (as indicated in the <SupportedEncryptionAlgorithms>
element of the <KeyProvClientHello> message in the case of 2-pass
DSKPP, or as otherwise known in the case of 1-pass DSKPP) are allowed
as values for the <xenc:EncryptionMethod> element. Further, in the
case of 2-pass DSKPP, the <ds:KeyInfo> element MUST contain the same
value (i.e. identify the same symmetric key) as the <Payload> of the
corresponding supported key initialization method in the
<KeyProvClientHello> message that triggered the response. The
<CarriedKeyName> element MAY be present, and MUST, when present,
contain the same value as the <KeyID> element of the
<KeyProvServerFinished> message. The Type attribute of the xenc:
EncryptedKeyType MUST be present and MUST identify the type of the
wrapped key. The type MUST be one of the types supported by the
DSKPP client (as reported in the <SupportedKeyTypes> of the preceding
<KeyProvClientHello> message in the case of 2-pass DSKPP, or as
otherwise known in the case of 1-pass DSKPP). The wrapped key MUST
consist of two parts of equal length. The first half constitutes
K_MAC and the second half constitutes K_TOKEN. The length of K_TOKEN
(and hence also the length of K_MAC) is determined by the type of
K_TOKEN.
DSKPP servers and cryptographic modules supporting this profile MUST
support the http://www.w3.org/2001/04/xmlenc#kw-aes128 key-wrapping
mechanism defined in [XMLENC].
When this profile is used, the MacAlgorithm attribute of the <Mac>
element of the <KeyProvServerFinished> message MUST be present and
MUST identify the selected MAC algorithm. The selected MAC algorithm
MUST be one of the MAC algorithms supported by the DSKPP client (as
indicated in the <SupportedMacAlgorithms> element of the
<KeyProvClientHello> message in the case of 2-pass DSKPP, or as
otherwise known in the case of 1-pass DSKPP). The MAC MUST be
calculated as described in Section 4.4.
In addition, DSKPP servers MUST include the AuthenticationDataType
element in their <KeyProvServerFinished> messages whenever a
successful protocol run will result in an existing K_TOKEN being
replaced.
11.4. Passphrase-Based Key Wrap Profile
11.4.1. Introduction
This profile is a variation of the key wrap profile. It initializes
the cryptographic module with a symmetric key, K_TOKEN, through key
wrap and key derivation, using a passphrase-derived key-wrapping key,
K_DERIVED. The passphrase is known in advance by both the device
user and the DSKPP server. To preserve the property of not exposing
K_TOKEN to any other entity than the DSKPP server and the
cryptographic module itself, the method SHOULD be employed only when
the device contains facilities (e.g. a keypad) for direct entry of
the passphrase. A key K from which two keys, K_TOKEN and K_MAC are
derived MUST be wrapped.
11.4.2. Identification
This profile MUST be identified with the following URI:
urn:ietf:params:xml:schema:keyprov:protocol#passphrase-wrap
11.4.3. Payloads
In the 2-pass version of DSKPP, the client MUST send a payload
associated with this key initialization method. The payload MUST be
of type ds:KeyInfoType ([XMLDSIG]). The ds:KeyName option MUST be
used and the key name MUST identify the passphrase that will be used
by the server to generate the key-wrapping key. As an example, the
identifier could be a user identifier or a registration identifier
issued by the server to the user during a session preceding the DSKPP
protocol run.
The server payload associated with this key initialization method
MUST be of type xenc:EncryptedKeyType ([XMLENC]), and only those
encryption methods utilizing a passphrase to derive the key-wrapping
key that are supported by the DSKPP client (as indicated in the
<SupportedEncryptionAlgorithms> element of the <KeyProvClientHello>
message in the case of 2-pass DSKPP, or as otherwise known in the
case of 1-pass DSKPP) are allowed as values for the <xenc:
EncryptionMethod> element. Further, in the case of 2-pass DSKPP, the
<ds:KeyInfo> element MUST contain the same value (i.e. identify the
same passphrase) as the <Payload> of the corresponding supported key
initialization method in the <KeyProvClientHello> message that
triggered the response. The <CarriedKeyName> element MAY be present,
and MUST, when present, contain the same value as the <KeyID> element
of the <KeyProvServerFinished> message. The Type attribute of the
xenc:EncryptedKeyType MUST be present and MUST identify the type of
the wrapped key. The type MUST be one of the types supported by the
DSKPP client (as reported in the <SupportedKeyTypes> of the preceding
<KeyProvClientHello> message in the case of 2-pass DSKPP, or as
otherwise known in the case of 1-pass DSKPP). The wrapped key MUST
consist of two parts of equal length. The first half constitutes
K_MAC and the second half constitutes K_TOKEN. The length of K_TOKEN
(and hence also the length of K_MAC) is determined by the type of
K_TOKEN.
DSKPP servers and cryptographic modules supporting this profile MUST
support the PBES2 password based encryption scheme defined in
[PKCS-5] (and identified as
http://www.rsasecurity.com/rsalabs/pkcs/schemas/pkcs-5#pbes2 in
[PKCS-5-XML]), the PBKDF2 passphrase-based key derivation function
also defined in [PKCS-5] (and identified as
http://www.rsasecurity.com/rsalabs/pkcs/schemas/pkcs-5#pbkdf2 in
[PKCS-5-XML]), and the http://www.w3.org/2001/04/xmlenc#kw-aes128
key-wrapping mechanism defined in [XMLENC].
When this profile is used, the MacAlgorithm attribute of the <Mac>
element of the <KeyProvServerFinished> message MUST be present and
MUST identify the selected MAC algorithm. The selected MAC algorithm
MUST be one of the MAC algorithms supported by the DSKPP client (as
indicated in the <SupportedMacAlgorithms> element of the
<KeyProvClientHello> message in the case of 2-pass DSKPP, or as
otherwise known in the case of 1-pass DSKPP). The MAC MUST be
calculated as described in Section 4.4.
In addition, DSKPP servers MUST include the AuthenticationDataType
element in their <KeyProvServerFinished> messages whenever a
successful protocol run will result in an existing K_TOKEN being
replaced.
12. Protocol Bindings
12.1. General Requirements 6.1. General Requirements
DSKPP assumes a reliable transport. DSKPP assumes a reliable transport.
12.2. HTTP/1.1 Binding for DSKPP 6.2. HTTP/1.1 Binding for DSKPP
12.2.1. Introduction 6.2.1. Introduction
This section presents a binding of the previous messages to HTTP/1.1 This section presents a binding of the previous messages to HTTP/1.1
[RFC2616]. Note that the HTTP client normally will be different from [RFC2616]. Note that the HTTP client normally will be different from
the DSKPP client, i.e., the HTTP client will only exist to "proxy" the DSKPP client, i.e., the HTTP client will only exist to "proxy"
DSKPP messages from the DSKPP client to the DSKPP server. Likewise, DSKPP messages from the DSKPP client to the DSKPP server. Likewise,
on the HTTP server side, the DSKPP server MAY receive DSKPP PDUs from on the HTTP server side, the DSKPP server MAY receive DSKPP PDUs from
a "front-end" HTTP server. a "front-end" HTTP server.
12.2.2. Identification of DSKPP Messages 6.2.2. Identification of DSKPP Messages
The MIME-type for all DSKPP messages MUST be The MIME-type for all DSKPP messages MUST be
application/vnd.ietf.keyprov.dskpp+xml application/vnd.ietf.keyprov.dskpp+xml
12.2.3. HTTP Headers 6.2.3. HTTP Headers
HTTP proxies MUST NOT cache responses carrying DSKPP messages. For HTTP proxies MUST NOT cache responses carrying DSKPP messages. For
this reason, the following holds: this reason, the following holds:
o When using HTTP/1.1, requesters SHOULD: o When using HTTP/1.1, requesters SHOULD:
* Include a Cache-Control header field set to "no-cache, no- * Include a Cache-Control header field set to "no-cache, no-
store". store".
* Include a Pragma header field set to "no-cache". * Include a Pragma header field set to "no-cache".
o When using HTTP/1.1, responders SHOULD: o When using HTTP/1.1, responders SHOULD:
* Include a Cache-Control header field set to "no-cache, no-must- * Include a Cache-Control header field set to "no-cache, no-must-
revalidate, private". revalidate, private".
* Include a Pragma header field set to "no-cache". * Include a Pragma header field set to "no-cache".
* NOT include a Validator, such as a Last-Modified or ETag * NOT include a Validator, such as a Last-Modified or ETag
header. header.
There are no other restrictions on HTTP headers, besides the There are no other restrictions on HTTP headers, besides the
requirement to set the Content-Type header value according to requirement to set the Content-Type header value according to
Section 12.2.2. Section 6.2.2.
12.2.4. HTTP Operations 6.2.4. HTTP Operations
Persistent connections as defined in HTTP/1.1 are assumed but not Persistent connections as defined in HTTP/1.1 are assumed but not
required. DSKPP requests are mapped to HTTP POST operations. DSKPP required. DSKPP requests are mapped to HTTP POST operations. DSKPP
responses are mapped to HTTP responses. responses are mapped to HTTP responses.
12.2.5. HTTP Status Codes 6.2.5. HTTP Status Codes
A DSKPP HTTP responder that refuses to perform a message exchange A DSKPP HTTP responder that refuses to perform a message exchange
with a DSKPP HTTP requester SHOULD return a 403 (Forbidden) response. with a DSKPP HTTP requester SHOULD return a 403 (Forbidden) response.
In this case, the content of the HTTP body is not significant. In In this case, the content of the HTTP body is not significant. In
the case of an HTTP error while processing a DSKPP request, the HTTP the case of an HTTP error while processing a DSKPP request, the HTTP
server MUST return a 500 (Internal Server Error) response. This type server MUST return a 500 (Internal Server Error) response. This type
of error SHOULD be returned for HTTP-related errors detected before of error SHOULD be returned for HTTP-related errors detected before
control is passed to the DSKPP processor, or when the DSKPP processor control is passed to the DSKPP processor, or when the DSKPP processor
reports an internal error (for example, the DSKPP XML namespace is reports an internal error (for example, the DSKPP XML namespace is
incorrect, or the DSKPP schema cannot be located). If the type of a incorrect, or the DSKPP schema cannot be located). If the type of a
skipping to change at page 75, line 29 skipping to change at page 52, line 5
In these cases (i.e., when the HTTP response code is 4xx or 5xx), the In these cases (i.e., when the HTTP response code is 4xx or 5xx), the
content of the HTTP body is not significant. content of the HTTP body is not significant.
Redirection status codes (3xx) apply as usual. Redirection status codes (3xx) apply as usual.
Whenever the HTTP POST is successfully invoked, the DSKPP HTTP Whenever the HTTP POST is successfully invoked, the DSKPP HTTP
responder MUST use the 200 status code and provide a suitable DSKPP responder MUST use the 200 status code and provide a suitable DSKPP
message (possibly with DSKPP error information included) in the HTTP message (possibly with DSKPP error information included) in the HTTP
body. body.
12.2.6. HTTP Authentication 6.2.6. HTTP Authentication
No support for HTTP/1.1 authentication is assumed. No support for HTTP/1.1 authentication is assumed.
12.2.7. Initialization of DSKPP 6.2.7. Initialization of DSKPP
The DSKPP server MAY initialize the DSKPP protocol by sending an HTTP The DSKPP server MAY initialize the DSKPP protocol by sending an HTTP
response with Content-Type set according to Section 12.2.2 and response with Content-Type set according to Section 6.2.2 and
response code set to 200 (OK). This message MAY, e.g., be sent in response code set to 200 (OK). This message MAY, e.g., be sent in
response to a user requesting key initialization in a browsing response to a user requesting key initialization in a browsing
session. The initialization message MAY carry data in its body. If session. The initialization message MAY carry data in its body. If
this is the case, the data MUST be a valid instance of a this is the case, the data MUST be a valid instance of a
<KeyProvTrigger> element. <KeyProvTrigger> element.
12.2.8. Example Messages 6.2.8. Example Messages
a. Initialization from DSKPP server: a. Initialization from DSKPP server:
HTTP/1.1 200 OK HTTP/1.1 200 OK
Cache-Control: no-store Cache-Control: no-store
Content-Type: application/vnd.ietf.keyprov.dskpp+xml Content-Type: application/vnd.ietf.keyprov.dskpp+xml
Content-Length: <some value> Content-Length: <some value>
DSKPP initialization data in XML form... DSKPP initialization data in XML form...
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c. Initial response from DSKPP server: c. Initial response from DSKPP server:
HTTP/1.1 200 OK HTTP/1.1 200 OK
Cache-Control: no-store Cache-Control: no-store
Content-Type: application/vnd.ietf.keyprov.dskpp+xml Content-Type: application/vnd.ietf.keyprov.dskpp+xml
Content-Length: <some value> Content-Length: <some value>
DSKPP data in XML form (server random nonce, server public key, DSKPP data in XML form (server random nonce, server public key,
...) ...)
13. DSKPP Schema 7. DSKPP Schema
<?xml version="1.0" encoding="UTF-8"?>
<?xml version="1.0" encoding="utf-8"?>
<xs:schema <xs:schema
xmlns:dskpp="urn:ietf:params:xml:ns:keyprov:1.0:protocol"
xmlns:pskc="urn:ietf:params:xml:ns:keyprov:1.0:container"
xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:xs="http://www.w3.org/2001/XMLSchema"
xmlns:dskpp="urn:ietf:params:xml:ns:keyprov:protocol:1.0"
xmlns:pskc="urn:ietf:params:xml:ns:keyprov:container:1.0"
xmlns:ds="http://www.w3.org/2000/09/xmldsig#" xmlns:ds="http://www.w3.org/2000/09/xmldsig#"
targetNamespace="urn:ietf:params:xml:ns:keyprov:1.0:protocol" elementFormDefault="qualified" attributeFormDefault="unqualified"
elementFormDefault="unqualified" attributeFormDefault="unqualified" targetNamespace="urn:ietf:params:xml:ns:keyprov:protocol:1.0"
version="1.0"> version="1.0">
<xs:import namespace="http://www.w3.org/2000/09/xmldsig#" <xs:import namespace="http://www.w3.org/2000/09/xmldsig#"
schemaLocation="http://www.w3.org/TR/2002/REC-xmldsig-core-20020212/xmldsig-core-schema.xsd"/> schemaLocation="http://www.w3.org/TR/2002/REC-xmldsig-core-20020212/
xmldsig-core-schema.xsd"/>
<xs:import namespace="urn:ietf:params:xml:ns:keyprov:1.0:container" <xs:import namespace="urn:ietf:params:xml:ns:keyprov:container:1.0"
schemaLocation="keyprov-pskc-1.0.xsd"/> schemaLocation="keyprov-pskc-1.0.xsd"/>
<!-- Basic types -->
<xs:complexType name="AbstractRequestType" abstract="true"> <xs:complexType name="AbstractRequestType" abstract="true">
<xs:attribute name="Version" type="dskpp:VersionType" use="required"/> <xs:annotation>
<xs:documentation> Basic types </xs:documentation>
</xs:annotation>
<xs:attribute name="Version" type="dskpp:VersionType"
use="required"/>
</xs:complexType> </xs:complexType>
<xs:complexType name="AbstractResponseType" abstract="true"> <xs:complexType name="AbstractResponseType" abstract="true">
<xs:attribute name="Version" type="dskpp:VersionType" use="required"/> <xs:annotation>
<xs:documentation> Basic types </xs:documentation>
</xs:annotation>
<xs:attribute name="Version" type="dskpp:VersionType"
use="required"/>
<xs:attribute name="SessionID" type="dskpp:IdentifierType"/> <xs:attribute name="SessionID" type="dskpp:IdentifierType"/>
<xs:attribute name="Status" type="dskpp:StatusCode" use="required"/> <xs:attribute name="Status" type="dskpp:StatusCode" use="required"/>
</xs:complexType> </xs:complexType>
<xs:simpleType name="VersionType"> <xs:simpleType name="VersionType">
<xs:restriction base="xs:string"> <xs:restriction base="xs:string">
<xs:pattern value="\d{1,2}\.\d{1,3}"/> <xs:pattern value="\d{1,2}\.\d{1,3}"/>
</xs:restriction> </xs:restriction>
</xs:simpleType> </xs:simpleType>
skipping to change at page 78, line 32 skipping to change at page 55, line 14
<xs:element name="Algorithm" type="dskpp:AlgorithmType"/> <xs:element name="Algorithm" type="dskpp:AlgorithmType"/>
</xs:sequence> </xs:sequence>
</xs:complexType> </xs:complexType>
<xs:simpleType name="AlgorithmType"> <xs:simpleType name="AlgorithmType">
<xs:restriction base="xs:anyURI"/> <xs:restriction base="xs:anyURI"/>
</xs:simpleType> <