draft-ietf-ace-oscore-profile-03.txt   draft-ietf-ace-oscore-profile-04.txt 
ACE Working Group L. Seitz ACE Working Group F. Palombini
Internet-Draft RISE SICS AB Internet-Draft Ericsson AB
Intended status: Standards Track F. Palombini Intended status: Standards Track L. Seitz
Expires: April 4, 2019 Ericsson AB Expires: April 11, 2019 RISE SICS AB
M. Gunnarsson
RISE SICS AB
G. Selander G. Selander
Ericsson AB Ericsson AB
October 1, 2018 M. Gunnarsson
RISE SICS AB
October 8, 2018
OSCORE profile of the Authentication and Authorization for Constrained OSCORE profile of the Authentication and Authorization for Constrained
Environments Framework Environments Framework
draft-ietf-ace-oscore-profile-03 draft-ietf-ace-oscore-profile-04
Abstract Abstract
This memo specifies a profile for the Authentication and This memo specifies a profile for the Authentication and
Authorization for Constrained Environments (ACE) framework. It Authorization for Constrained Environments (ACE) framework. It
utilizes Object Security for Constrained RESTful Environments utilizes Object Security for Constrained RESTful Environments
(OSCORE) to provide communication security, server authentication, (OSCORE) to provide communication security, server authentication,
and proof-of-possession for a key owned by the client and bound to an and proof-of-possession for a key owned by the client and bound to an
OAuth 2.0 access token. OAuth 2.0 access token.
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on April 4, 2019. This Internet-Draft will expire on April 11, 2019.
Copyright Notice Copyright Notice
Copyright (c) 2018 IETF Trust and the persons identified as the Copyright (c) 2018 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of (https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2. Protocol Overview . . . . . . . . . . . . . . . . . . . . . . 3 2. Protocol Overview . . . . . . . . . . . . . . . . . . . . . . 3
3. Client-AS Communication . . . . . . . . . . . . . . . . . . . 5 3. Client-AS Communication . . . . . . . . . . . . . . . . . . . 5
3.1. C-to-AS: POST /token . . . . . . . . . . . . . . . . . . 5 3.1. C-to-AS: POST /token . . . . . . . . . . . . . . . . . . 5
3.2. AS-to-C: Access Token . . . . . . . . . . . . . . . . . . 6 3.2. AS-to-C: Access Token . . . . . . . . . . . . . . . . . . 7
4. Client-RS Communication . . . . . . . . . . . . . . . . . . . 11 4. Client-RS Communication . . . . . . . . . . . . . . . . . . . 11
4.1. C-to-RS: POST /authz-info . . . . . . . . . . . . . . . . 11 4.1. C-to-RS: POST /authz-info . . . . . . . . . . . . . . . . 12
4.2. RS-to-C: 2.01 (Created) . . . . . . . . . . . . . . . . . 11 4.2. RS-to-C: 2.01 (Created) . . . . . . . . . . . . . . . . . 12
4.3. OSCORE Setup . . . . . . . . . . . . . . . . . . . . . . 12 4.3. OSCORE Setup . . . . . . . . . . . . . . . . . . . . . . 13
4.4. Access rights verification . . . . . . . . . . . . . . . 13 4.4. Access rights verification . . . . . . . . . . . . . . . 15
5. Secure Communication with AS . . . . . . . . . . . . . . . . 14 5. Secure Communication with AS . . . . . . . . . . . . . . . . 15
6. Security Considerations . . . . . . . . . . . . . . . . . . . 14 6. Security Considerations . . . . . . . . . . . . . . . . . . . 15
7. Privacy Considerations . . . . . . . . . . . . . . . . . . . 15 7. Privacy Considerations . . . . . . . . . . . . . . . . . . . 16
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 16 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 18
9.1. Normative References . . . . . . . . . . . . . . . . . . 16 9.1. Normative References . . . . . . . . . . . . . . . . . . 18
9.2. Informative References . . . . . . . . . . . . . . . . . 17 9.2. Informative References . . . . . . . . . . . . . . . . . 19
Appendix A. Profile Requirements . . . . . . . . . . . . . . . . 17 Appendix A. Profile Requirements . . . . . . . . . . . . . . . . 19
Appendix B. Using the pop-key with EDHOC (EDHOC+OSCORE) . . . . 18 Appendix B. Using the pop-key with EDHOC (EDHOC+OSCORE) . . . . 20
B.1. Using Asymmetric Keys . . . . . . . . . . . . . . . . . . 18 B.1. Using Asymmetric Keys . . . . . . . . . . . . . . . . . . 20
B.2. Using Symmetric Keys . . . . . . . . . . . . . . . . . . 20 B.2. Using Symmetric Keys . . . . . . . . . . . . . . . . . . 22
B.3. Processing . . . . . . . . . . . . . . . . . . . . . . . 22 B.3. Processing . . . . . . . . . . . . . . . . . . . . . . . 24
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 23 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 25
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 24 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 26
1. Introduction 1. Introduction
This memo specifies a profile of the ACE framework This memo specifies a profile of the ACE framework
[I-D.ietf-ace-oauth-authz]. In this profile, a client and a resource [I-D.ietf-ace-oauth-authz]. In this profile, a client and a resource
server use CoAP [RFC7252] to communicate. The client uses an access server use CoAP [RFC7252] to communicate. The client uses an access
token, bound to a key (the proof-of-possession key) to authorize its token, bound to a key (the proof-of-possession key) to authorize its
access to the resource server. In order to provide communication access to the resource server. In order to provide communication
security, proof of possession, and server authentication they use security, proof of possession, and server authentication they use
Object Security for Constrained RESTful Environments (OSCORE) Object Security for Constrained RESTful Environments (OSCORE)
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Terminology for entities in the architecture is defined in OAuth 2.0 Terminology for entities in the architecture is defined in OAuth 2.0
[RFC6749], such as client (C), resource server (RS), and [RFC6749], such as client (C), resource server (RS), and
authorization server (AS). It is assumed in this document that a authorization server (AS). It is assumed in this document that a
given resource on a specific RS is associated to a unique AS. given resource on a specific RS is associated to a unique AS.
2. Protocol Overview 2. Protocol Overview
This section gives an overview on how to use the ACE Framework This section gives an overview on how to use the ACE Framework
[I-D.ietf-ace-oauth-authz] to secure the communication between a [I-D.ietf-ace-oauth-authz] to secure the communication between a
client and a resource server using OSCORE client and a resource server using OSCORE
[I-D.ietf-core-object-security]. The parameters needed to negotiate [I-D.ietf-core-object-security]. The parameters needed by the client
the use of this profile with the token resource at the authorization to negotiate the use of this profile with the authorization server,
server as specified in section 5.6 of [I-D.ietf-ace-oauth-authz] are as well as OSCORE setup process, are described in detail in the
described in detail in the following sections. following sections.
This profile requires a client to retrieve an access token from the This profile requires a client to retrieve an access token from the
AS for the resource it wants to access on a RS, using the token AS for the resource it wants to access on a RS, using the token
endpoint, as specified in section 5.6.1 of resource, as specified in section 5.6 of [I-D.ietf-ace-oauth-authz].
[I-D.ietf-ace-oauth-authz]. To determine the AS in charge of a To determine the AS in charge of a resource hosted at the RS, the
resource hosted at the RS, the client C MAY send an initial client C MAY send an initial Unauthorized Resource Request message to
Unauthorized Resource Request message to the RS. The RS then denies the RS. The RS then denies the request and sends the address of its
the request and sends the address of its AS back to the client C as AS back to the client C as specified in section 5.1 of
specified in section 5.1 of [I-D.ietf-ace-oauth-authz]. The access [I-D.ietf-ace-oauth-authz]. The access token request and response
token request and response MUST be confidentiality-protected and MUST be confidentiality-protected and ensure authenticity. This
ensure authenticity. This profile RECOMMENDS the use of OSCORE profile RECOMMENDS the use of OSCORE between client and AS, but TLS
between client and AS, but TLS or DTLS MAY be used additionally or or DTLS MAY be used additionally or instead.
instead.
Once the client has retrieved the access token, it forwards it to the Once the client has retrieved the access token, it posts it to the RS
RS using the authz-info endpoint and mechanisms specified in section using the authz-info resource and mechanisms specified in section 5.8
5.8.1. of [I-D.ietf-ace-oauth-authz]. If the access token is valid, of [I-D.ietf-ace-oauth-authz]. If the access token is valid, the RS
the RS replies to this request with a 2.01 (Created) response, which replies to this request with a 2.01 (Created) response, which
contains a nonce N1. contains a nonce N1.
After receiving the nonce N1, the client generates a nonce N2, After receiving the nonce N1, the client generates a nonce N2,
concatenates it with N1 and sets the ID Context in its Security concatenates it with N1 and sets the ID Context in its Security
Context (see section 3 of [I-D.ietf-core-object-security]) to N1 Context (see section 3 of [I-D.ietf-core-object-security]) to N1
concatenated with N2. The client then derives the complete Security concatenated with N2. The client then derives the complete Security
Context from the ID Context plus the parameters received from the AS. Context from the ID Context plus the parameters received from the AS.
Finally, the client sends a request protected with OSCORE to the RS. Finally, the client sends a request protected with OSCORE to the RS.
This message contains the ID Context value. When receiving this This message contains the ID Context value. When receiving this
request after the 2.01 (Created) response, the server extract the ID request after the 2.01 (Created) response, the server extract the ID
Context from it, verifies that the first part is equal to the nonce Context from it, verifies that the first part is equal to the nonce
N1 it previously sent, and if so, sets its own ID Context and derives N1 it previously sent, and if so, sets its own ID Context and derives
the complete Security Context from it plus the parameters received in the complete Security Context from it plus the parameters received in
the AS, following section 3.2 of [I-D.ietf-core-object-security]. If the AS, following section 3.2 of [I-D.ietf-core-object-security]. If
the request verifies, then this Security Context is stored in the the request verifies, then this Security Context is stored in the
server, and used in the response, and in further communications with server, and used in the response, and in further communications with
the client, until token expiration. The client will not include the the client, until token expiration. Once the client receives a valid
ID Context value in further requests. response, it does not continue to include the ID Context value in
further requests.
An overview of the profile flow for the OSCORE profile is given in An overview of the profile flow for the OSCORE profile is given in
Figure 1. Figure 1.
C RS AS C RS AS
| [-- Resource Request --->] | | | [-- Resource Request --->] | |
| | | | | |
| [<----- AS Information --] | | | [<----- AS Information --] | |
| | | | | |
| ----- POST /token ----------------------------> | | ----- POST /token ----------------------------> |
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| | | | | |
| <--- OSCORE Response ----- | | | <--- OSCORE Response ----- | |
| ... | | | ... | |
Figure 1: Protocol Overview Figure 1: Protocol Overview
3. Client-AS Communication 3. Client-AS Communication
The following subsections describe the details of the POST /token The following subsections describe the details of the POST /token
request and response between client and AS. Section 3.2 of request and response between client and AS. Section 3.2 of
[I-D.ietf-core-object-security] defines how to derive a security [I-D.ietf-core-object-security] defines how to derive a Security
context based on a shared master secret and a set of other Context based on a shared master secret and a set of other
parameters, established between client and server, which the client parameters, established between client and server, which the client
receives from the AS in this exchange. The proof-of-possession key receives from the AS in this exchange. The proof-of-possession key
(pop-key) provisioned from the AS MUST be used as master secret in (pop-key) provisioned from the AS MUST be used as master secret in
OSCORE. OSCORE.
3.1. C-to-AS: POST /token 3.1. C-to-AS: POST /token
The client-to-AS request is specified in Section 5.6.1 of The client-to-AS request is specified in Section 5.6.1 of
[I-D.ietf-ace-oauth-authz]. [I-D.ietf-ace-oauth-authz].
If the client wants to update its access rights using the same OSCORE
Security Context, it MUST include in its POST /token request a cnf
object carrying the Sender ID in the kid field. This identifier can
be used by the AS to determine the shared secret to construct the
proof-of-possession token and therefore MUST specify a symmetric key
that was previously generated by the AS as a shared secret for the
communication between the client and the RS.
The client MUST send this POST /token request over a secure channel The client MUST send this POST /token request over a secure channel
that guarantees authentication, message integrity and confidentiality that guarantees authentication, message integrity and confidentiality
(see Section 5). (see Section 5).
An example of such a request, in CBOR diagnostic notation without the An example of such a request, in CBOR diagnostic notation without the
tag and value abbreviations is reported in Figure 2 tag and value abbreviations is reported in Figure 2
Header: POST (Code=0.02) Header: POST (Code=0.02)
Uri-Host: "as.example.com" Uri-Host: "as.example.com"
Uri-Path: "token" Uri-Path: "token"
Content-Format: "application/ace+cbor" Content-Format: "application/ace+cbor"
Payload: Payload:
{ {
"grant_type" : "client_credentials", "grant_type" : "client_credentials",
"client_id" : "myclient", "client_id" : "myclient",
"aud" : "tempSensor4711" "req_aud" : "tempSensor4711",
"scope" : "read"
} }
Figure 2: Example C-to-AS POST /token request for an access token Figure 2: Example C-to-AS POST /token request for an access token
bound to a symmetric key. bound to a symmetric key.
If the client wants to update its access rights without changing an
existing OSCORE Security Context, it MUST include in its POST /token
request a req_cnf object carrying the client's identifier (that was
assigned in section Section 3.2) in the kid field. This identifier
can be used by the AS to determine the shared secret to construct the
proof-of-possession token and therefore MUST identify a symmetric key
that was previously generated by the AS as a shared secret for the
communication between the client and the RS. The AS MUST verify that
the received value identifies a proof-of-possession key and token
that have previously been issued to the requesting client. If that
is not the case, the Client-to-AS request MUST be declined with the
error code 'invalid_request' as defined in Section 5.6.3 of
[I-D.ietf-ace-oauth-authz].
An example of such a request, in CBOR diagnostic notation without the
tag and value abbreviations is reported in Figure 3
Header: POST (Code=0.02)
Uri-Host: "as.example.com"
Uri-Path: "token"
Content-Format: "application/ace+cbor"
Payload:
{
"grant_type" : "client_credentials",
"client_id" : "myclient",
"req_aud" : "tempSensor4711",
"scope" : "write",
"req_cnf" : {
"kid" : b64'Qg'
}
Figure 3: Example C-to-AS POST /token request for updating rights to
an access token bound to a symmetric key.
3.2. AS-to-C: Access Token 3.2. AS-to-C: Access Token
After verifying the POST /token request and that the client is After verifying the POST /token request and that the client is
authorized to obtain an access token corresponding to its access authorized to obtain an access token corresponding to its access
token request, the AS responds as defined in section 5.6.2 of token request, the AS responds as defined in section 5.6.2 of
[I-D.ietf-ace-oauth-authz]. It signals that the use of OSCORE is [I-D.ietf-ace-oauth-authz]. If the client request was invalid, or
REQUIRED for a specific access token by including the "profile" not authorized, the AS returns an error response as described in
parameter with the value "coap_oscore" in the access token response. section 5.6.3 of [I-D.ietf-ace-oauth-authz].
This means that the client MUST use OSCORE towards all resource
servers for which this access token is valid, and follow Section 4.3
to derive the security context to run OSCORE.
The error response procedures defined in section 5.6.3 of the ACE The AS signals that the use of OSCORE is REQUIRED for a specific
framework are unchanged by this profile. access token by including the "profile" parameter with the value
"coap_oscore" in the access token response. This means that the
client MUST use OSCORE towards all resource servers for which this
access token is valid, and follow Section 4.3 to derive the security
context to run OSCORE.
Moreover, the AS MUST provision the following data: Moreover, the AS MUST provision the following data:
o a master secret o a master secret
o a client identifier o a client identifier
o a server identifier o a server identifier
Additionally, the AS MAY provision the following data, in the same Additionally, the AS MAY provision the following data, in the same
response. response.
o an AEAD algorithm o an AEAD algorithm
o an HKDF algorithm o an HKDF algorithm
o a salt o a salt
o a replay window type and size o a replay window type and size
The master secret MUST be communicated as COSE_Key in the 'cnf' The master secret MUST be communicated as COSE_Key in the 'cnf'
parameter of the access token response as defined in Section 5.6.4.5 parameter of the access token response as defined in Section 3.2 of
of [I-D.ietf-ace-oauth-authz]. The AEAD algorithm MAY be included as [I-D.ietf-ace-oauth-params]. The AEAD algorithm MAY be included as
the 'alg' parameter in the COSE_Key; the HKDF algorithm MAY be the 'alg' parameter in the COSE_Key; the HKDF algorithm MAY be
included as the 'hkdf' parameter of the COSE_Key and the salt MAY be included as the 'hkdf' parameter of the COSE_Key and the salt MAY be
included as the 'slt' parameter of the COSE_Key as defined in included as the 'slt' parameter of the COSE_Key as defined in
Figure 3. Figure 4.
The same parameters MUST be included as metadata of the access token. The same parameters MUST be included as metadata of the access token.
This profile RECOMMENDS the use of CBOR web token (CWT) as specified This profile RECOMMENDS the use of CBOR web token (CWT) as specified
in [RFC8392]. If the token is a CWT, the same COSE_Key structure in [RFC8392]. If the token is a CWT, the same COSE_Key structure
defined above MUST be placed in the 'cnf' claim of this token. defined above MUST be placed in the 'cnf' claim of this token.
The AS MUST also assign identifiers to both client and RS, which are The AS MUST also assign identifiers to both client and RS, which are
then used as Sender ID and Recipient ID in the OSCORE context as then used as Sender ID and Recipient ID in the OSCORE context as
described in section 3.1 of [I-D.ietf-core-object-security]. These described in section 3.1 of [I-D.ietf-core-object-security]. These
identifiers MUST be unique in the set of all clients and RS identifiers MUST be unique in the set of all clients and RS
identifiers for a certain AS. Moreover, these MUST be included in identifiers for a certain AS. Moreover, these MUST be included in
the COSE_Key as header parameters, as defined in Figure 3. the COSE_Key as header parameters, as defined in Figure 4.
We assume in this document that a resource is associated to one We assume in this document that a resource is associated to one
single AS, which makes it possible to assume unique identifiers for single AS, which makes it possible to assume unique identifiers for
each client requesting a particular resource to a RS. If this is not each client requesting a particular resource to a RS. If this is not
the case, collisions of identifiers may appear in the RS, in which the case, collisions of identifiers may appear in the RS, in which
case the RS needs to have a mechanism in place to disambiguate case the RS needs to have a mechanism in place to disambiguate
identifiers or mitigate their effect. identifiers or mitigate their effect.
Note that C should set the Sender ID of its Security Context to the Note that in Section 4.3 C sets the Sender ID of its Security Context
clientId value received and the Recipient ID to the serverId value, to the clientId value received and the Recipient ID to the serverId
and RS should do the opposite. value, and RS does the opposite.
+----------+-------+--------------+------------+-------------------+ +----------+-------+--------------+------------+-------------------+
| name | label | CBOR type | registry | description | | name | label | CBOR type | registry | description |
+----------+-------+--------------+------------+-------------------+ +----------+-------+--------------+------------+-------------------+
| clientId | TBD1 | bstr | | Identifies the | | clientId | TBD1 | bstr | | Identifies the |
| | | | | client in an | | | | | | client in an |
| | | | | OSCORE context | | | | | | OSCORE context |
| | | | | using this key | | | | | | using this key |
| | | | | | | | | | | |
| serverId | TBD2 | bstr | | Identifies the | | serverId | TBD2 | bstr | | Identifies the |
skipping to change at page 8, line 29 skipping to change at page 9, line 29
| | | | | KDF algorithm in | | | | | | KDF algorithm in |
| | | | | an OSCORE context | | | | | | an OSCORE context |
| | | | | using this key | | | | | | using this key |
| | | | | | | | | | | |
| slt | TBD4 | bstr | | Identifies the | | slt | TBD4 | bstr | | Identifies the |
| | | | | master salt in | | | | | | master salt in |
| | | | | an OSCORE context | | | | | | an OSCORE context |
| | | | | using this key | | | | | | using this key |
+----------+-------+--------------+------------+-------------------+ +----------+-------+--------------+------------+-------------------+
Figure 3: Additional COSE_Key Common Parameters Figure 4: Additional COSE_Key Common Parameters
Figure 4 shows an example of such an AS response, in CBOR diagnostic Figure 5 shows an example of such an AS response, in CBOR diagnostic
notation without the tag and value abbreviations. notation without the tag and value abbreviations.
Header: Created (Code=2.01) Header: Created (Code=2.01)
Content-Type: "application/cose+cbor" Content-Type: "application/cose+cbor"
Payload: Payload:
{ {
"access_token" : b64'SlAV32hkKG ... "access_token" : b64'SlAV32hkKG ...
(remainder of access token omitted for brevity)', (remainder of access token omitted for brevity)',
"profile" : "coap_oscore", "profile" : "coap_oscore",
"expires_in" : "3600", "expires_in" : "3600",
skipping to change at page 9, line 24 skipping to change at page 10, line 24
"COSE_Key" : { "COSE_Key" : {
"kty" : "Symmetric", "kty" : "Symmetric",
"alg" : "AES-CCM-16-64-128", "alg" : "AES-CCM-16-64-128",
"clientId" : b64'qA', "clientId" : b64'qA',
"serverId" : b64'Qg', "serverId" : b64'Qg',
"k" : b64'+a+Dg2jjU+eIiOFCa9lObw' "k" : b64'+a+Dg2jjU+eIiOFCa9lObw'
} }
} }
} }
Figure 4: Example AS-to-C Access Token response with OSCORE profile. Figure 5: Example AS-to-C Access Token response with OSCORE profile.
Figure 5 shows an example CWT, containing the necessary OSCORE Figure 6 shows an example CWT, containing the necessary OSCORE
parameters in the 'cnf' claim, in CBOR diagnostic notation without parameters in the 'cnf' claim, in CBOR diagnostic notation without
tag and value abbreviations. tag and value abbreviations.
{ {
"aud" : "tempSensorInLivingRoom", "aud" : "tempSensorInLivingRoom",
"iat" : "1360189224", "iat" : "1360189224",
"exp" : "1360289224", "exp" : "1360289224",
"scope" : "temperature_g firmware_p", "scope" : "temperature_g firmware_p",
"cnf" : { "cnf" : {
"COSE_Key" : { "COSE_Key" : {
"kty" : "Symmetric", "kty" : "Symmetric",
"alg" : "AES-CCM-16-64-128", "alg" : "AES-CCM-16-64-128",
"clientId" : b64'Qg', "clientId" : b64'Qg',
"serverId" : b64'qA', "serverId" : b64'qA',
"k" : b64'+a+Dg2jjU+eIiOFCa9lObw' "k" : b64'+a+Dg2jjU+eIiOFCa9lObw'
} }
} }
Figure 5: Example CWT with OSCORE parameters. Figure 6: Example CWT with OSCORE parameters.
If the client has requested an update to its access rights using the If the client has requested an update to its access rights using the
same OSCORE Security Context, and the token associated with it is not same OSCORE Security Context, which is valid and authorized, the AS
expired, the AS MAY omit the master secret and server identifier both MUST omit the 'cnf' parameter in the response, and MUST carry the
in the COSE_Key in the 'cnf' parameter and in the token. The client client identifier in the 'kid' field in the 'cnf' parameter of the
identifier needs to be provisioned, in order for the RS to identify token. The client identifier needs to be provisioned, in order for
the previously generated Security Context. the RS to identify the previously generated Security Context.
Figure 6 shows an example of such an AS response, in CBOR diagnostic Figure 7 shows an example of such an AS response, in CBOR diagnostic
notation without the tag and value abbreviations. notation without the tag and value abbreviations.
Header: Created (Code=2.01) Header: Created (Code=2.01)
Content-Type: "application/cose+cbor" Content-Type: "application/cose+cbor"
Payload: Payload:
{ {
"access_token" : b64'SlAV32hkKG ... "access_token" : b64'SlAV32hkKG ...
(remainder of access token omitted for brevity)', (remainder of access token omitted for brevity)',
"profile" : "coap_oscore", "profile" : "coap_oscore",
"expires_in" : "3600", "expires_in" : "3600"
"cnf" : {
"COSE_Key" : {
"clientId" : b64'qA'
}
}
} }
Figure 6: Example AS-to-C Access Token response with OSCORE profile, Figure 7: Example AS-to-C Access Token response with OSCORE profile,
for update of access rights. for update of access rights.
Figure 7 shows an example CWT, containing the necessary OSCORE Figure 8 shows an example CWT, containing the necessary OSCORE
parameters in the 'cnf' claim for update of access rights, in CBOR parameters in the 'cnf' claim for update of access rights, in CBOR
diagnostic notation without tag and value abbreviations. diagnostic notation without tag and value abbreviations.
{ {
"aud" : "tempSensorInLivingRoom", "aud" : "tempSensorInLivingRoom",
"iat" : "1360189224", "iat" : "1360189224",
"exp" : "1360289224", "exp" : "1360289224",
"scope" : "temperature_h", "scope" : "temperature_h",
"cnf" : { "cnf" : {
"COSE_Key" : { "kid" : b64'Qg'
"clientId" : b64'Qg'
} }
} }
Figure 7: Example CWT with OSCORE parameters for update of access Figure 8: Example CWT with OSCORE parameters for update of access
rights. rights.
4. Client-RS Communication 4. Client-RS Communication
The following subsections describe the details of the POST /authz- The following subsections describe the details of the POST /authz-
info request and response between client and RS. The client posts info request and response between client and RS. The client posts
the token that includes the materials provisioned by the AS to the the token that includes the materials provisioned by the AS to the
RS, which can then use Section 3.2 of [I-D.ietf-core-object-security] RS, which can then use Section 3.2 of [I-D.ietf-core-object-security]
to derive a security context based on a shared master secret and a to derive a security context based on a shared master secret and a
set of other parameters, established between client and server. set of other parameters, established between client and server.
Note that the proof-of-possession required to bind the access token Note that the proof-of-possession required to bind the access token
to the client is implicitly performed by generating the shared OSCORE to the client is implicitly performed by generating the shared OSCORE
Security Context using the pop-key as master secret, for both client Security Context using the pop-key as master secret, for both client
and RS. An attacker using a stolen token will not be able to and RS. An attacker using a stolen token will not be able to
generate a valid OSCORE context and thus not be able to prove generate a valid OSCORE context and thus not be able to prove
possession of the pop-key. possession of the pop-key.
4.1. C-to-RS: POST /authz-info 4.1. C-to-RS: POST /authz-info
The client MUST use CoAP and the Authorization Information endpoint The client MUST use CoAP and the Authorization Information resource
as described in section 5.8.1 of [I-D.ietf-ace-oauth-authz] to as described in section 5.8.1 of [I-D.ietf-ace-oauth-authz] to
transport the token to the RS. transport the token to the RS.
The authz-info endpoint is not protected, nor are the responses from The authz-info resource is not protected, nor are the responses from
this endpoint. this resource.
The access token MUST be encrypted, since it is transferred from the The access token MUST be encrypted, since it is transferred from the
client to the RS over an unprotected channel. client to the RS over an unprotected channel.
Figure 8 shows an example of the request sent from the client to the Note that a client may be required to re-POST the access token, since
an RS may delete a stored access token, due to lack of memory.
Figure 9 shows an example of the request sent from the client to the
RS. RS.
Header: POST (Code=0.02) Header: POST (Code=0.02)
Uri-Host: "rs.example.com" Uri-Host: "rs.example.com"
Uri-Path: "authz-info" Uri-Path: "authz-info"
Content-Format: "application/cwt" Content-Format: "application/cwt"
Payload: Payload:
b64'SlAV32hkKG ... b64'SlAV32hkKG ...
(remainder of access token omitted for brevity)', (remainder of access token omitted for brevity)',
Figure 8: Example C-to-RS POST /authz-info request using CWT Figure 9: Example C-to-RS POST /authz-info request using CWT
4.2. RS-to-C: 2.01 (Created) 4.2. RS-to-C: 2.01 (Created)
The RS MUST follow the procedures defined in section 5.8.1 of The RS MUST follow the procedures defined in section 5.8.1 of
[I-D.ietf-ace-oauth-authz]: the RS MUST verify the validity of the [I-D.ietf-ace-oauth-authz]: the RS MUST verify the validity of the
token. If the token is valid, the RS MUST respond to the POST token. If the token is valid, the RS MUST respond to the POST
request with 2.01 (Created). This response MAY contain an identifier request with 2.01 (Created). If the token is valid but is associated
of the token (e.g., the cti for a CWT) as a payload, in order to to claims that the RS cannot process (e.g., an unknown scope) the RS
allow the client to refer to the token. If the token is valid but is MUST respond with a response code equivalent to the CoAP code 4.00
associated to claims that the RS cannot process (e.g., an unknown (Bad Request). In the latter case the RS MAY provide additional
scope) the RS MUST respond with a response code equivalent to the information in the error response, in order to clarify what went
CoAP code 4.00 (Bad Request). In the latter case the RS MAY provide wrong. The RS MAY make an introspection request to validate the
additional information in the error response, in order to clarify token before responding to the POST request to the authz-info
what went wrong. The RS MAY make an introspection request to resource.
validate the token before responding to the POST request to the
authz-info endpoint.
Additionally, the RS MUST generate a nonce (N1) with a good amount of Additionally, the RS MUST generate a nonce (N1) with a good amount of
randomness, and include it in the payload of the 2.01 (Created) randomness, and include it in the payload of the 2.01 (Created)
response as a CBOR byte string. This profile RECOMMENDS to use a response as a CBOR byte string. This profile RECOMMENDS to use a
nonce of 64 bits. The RS MUST store this nonce as long as the access nonce of 64 bits. The RS MUST store this nonce as long as the access
token related to it is still valid. token related to it is still valid.
Figure 9 shows an example of the response sent from the RS to the Note that, when using this profile, an identifier of the token (e.g.,
the cti for a CWT) is not transported in the payload of this request,
as section 5.8.1 of [I-D.ietf-ace-oauth-authz] allows.
Figure 10 shows an example of the response sent from the RS to the
client. client.
Header: Created (Code=2.01) Header: Created (Code=2.01)
Content-Format: "application/cbor" Content-Format: "application/cbor"
Payload: Payload:
h'018a278f7faab55a', h'018a278f7faab55a',
Figure 9: Example RS-to-C 2.01 (Created) response Figure 10: Example RS-to-C 2.01 (Created) response
When receiving an updated access token with updated authorization
information from the client (see section Section 3.1), it is
RECOMMENDED that the RS overwrites the previous token, that is only
the latest authorization information in the token received by the RS
is valid. This simplifies for the RS to keep track of authorization
information for a given client.
As specified in section 5.8.3 of [I-D.ietf-ace-oauth-authz], the RS As specified in section 5.8.3 of [I-D.ietf-ace-oauth-authz], the RS
MUST notify the client with an error response with code 4.01 MUST notify the client with an error response with code 4.01
(Unauthorized) for any long running request before terminating the (Unauthorized) for any long running request before terminating the
session, when the access token expires. session, when the access token expires.
4.3. OSCORE Setup 4.3. OSCORE Setup
Once receiving the 2.01 (Created) response from the RS, following the Once receiving the 2.01 (Created) response from the RS, following the
POST /authz-info request, the client MUST extract the nonce N1 from POST /authz-info request, the client MUST extract the nonce N1 from
skipping to change at page 13, line 48 skipping to change at page 15, line 8
responses are used, as specified in section 8 of responses are used, as specified in section 8 of
[I-D.ietf-core-object-security]. Additionally, if OSCORE [I-D.ietf-core-object-security]. Additionally, if OSCORE
verification succeeds, the verification of access rights is performed verification succeeds, the verification of access rights is performed
as described in section Section 4.4. The RS MUST NOT use the as described in section Section 4.4. The RS MUST NOT use the
Security Context after the related token has expired, and MUST Security Context after the related token has expired, and MUST
respond with a unprotected 4.01 (Unauthorized) error message. respond with a unprotected 4.01 (Unauthorized) error message.
4.4. Access rights verification 4.4. Access rights verification
The RS MUST follow the procedures defined in section 5.8.2 of The RS MUST follow the procedures defined in section 5.8.2 of
[I-D.ietf-ace-oauth-authz]: if an RS receives a OSCORE-protected [I-D.ietf-ace-oauth-authz]: if an RS receives an OSCORE-protected
request from a client, then it processes according to request from a client, then it processes according to
[I-D.ietf-core-object-security]. If OSCORE verification succeeds, [I-D.ietf-core-object-security]. If OSCORE verification succeeds,
and the target resource requires authorization, the RS retrieves the and the target resource requires authorization, the RS retrieves the
authorization information from the access token associated to the authorization information from the access token associated to the
Security Context. The RS then MUST verify that the authorization Security Context. The RS then MUST verify that the authorization
information covers the resource and the action requested. information covers the resource and the action requested.
The response code MUST be 4.01 (Unauthorized) in case the client has The response code MUST be 4.01 (Unauthorized) in case the client has
not used the Security Context associated with the access token, or if not used the Security Context associated with the access token, or if
RS has no valid access token for the client. If RS has an access RS has no valid access token for the client. If RS has an access
token for the client but not for the resource that was requested, RS token for the client but not for the resource that was requested, RS
MUST reject the request with a 4.03 (Forbidden). If RS has an access MUST reject the request with a 4.03 (Forbidden). If RS has an access
token for the client but it does not cover the action that was token for the client but it does not cover the action that was
requested on the resource, RS MUST reject the request with a 4.05 requested on the resource, RS MUST reject the request with a 4.05
(Method Not Allowed). (Method Not Allowed).
5. Secure Communication with AS 5. Secure Communication with AS
As specified in the ACE framework (section 5.7 of As specified in the ACE framework (section 5.7 of
[I-D.ietf-ace-oauth-authz]), the requesting entity (RS and/or client) [I-D.ietf-ace-oauth-authz]), the requesting entity (RS and/or client)
and the AS communicates via the introspection or token endpoint. The and the AS communicates via the introspection or token resource. The
use of CoAP and OSCORE for this communication is RECOMMENDED in this use of CoAP and OSCORE for this communication is RECOMMENDED in this
profile, other protocols (such as HTTP and DTLS or TLS) MAY be used profile, other protocols (such as HTTP and DTLS or TLS) MAY be used
instead. instead.
If OSCORE is used, the requesting entity and the AS are expected to If OSCORE is used, the requesting entity and the AS are expected to
have pre-established security contexts in place. How these security have pre-established security contexts in place. How these security
contexts are established is out of scope for this profile. contexts are established is out of scope for this profile.
Furthermore the requesting entity and the AS communicate using OSCORE Furthermore the requesting entity and the AS communicate using OSCORE
([I-D.ietf-core-object-security]) through the introspection endpoint ([I-D.ietf-core-object-security]) through the introspection resource
as specified in section 5.7 of [I-D.ietf-ace-oauth-authz] and through as specified in section 5.7 of [I-D.ietf-ace-oauth-authz] and through
the token endpoint as specified in section 5.6 of the token resource as specified in section 5.6 of
[I-D.ietf-ace-oauth-authz]. [I-D.ietf-ace-oauth-authz].
6. Security Considerations 6. Security Considerations
This document specifies a profile for the Authentication and This document specifies a profile for the Authentication and
Authorization for Constrained Environments (ACE) framework Authorization for Constrained Environments (ACE) framework
[I-D.ietf-ace-oauth-authz]. Thus the general security considerations [I-D.ietf-ace-oauth-authz]. Thus the general security considerations
from the framework also apply to this profile. from the framework also apply to this profile.
Furthermore the general security considerations of OSCORE Furthermore the general security considerations of OSCORE
skipping to change at page 15, line 7 skipping to change at page 16, line 13
the OSCORE protocol. the OSCORE protocol.
OSCORE is designed to secure point-to-point communication, providing OSCORE is designed to secure point-to-point communication, providing
a secure binding between the request and the response(s). Thus the a secure binding between the request and the response(s). Thus the
basic OSCORE protocol is not intended for use in point-to-multipoint basic OSCORE protocol is not intended for use in point-to-multipoint
communication (e.g. multicast, publish-subscribe). Implementers of communication (e.g. multicast, publish-subscribe). Implementers of
this profile should make sure that their usecase corresponds to the this profile should make sure that their usecase corresponds to the
expected use of OSCORE, to prevent weakening the security assurances expected use of OSCORE, to prevent weakening the security assurances
provided by OSCORE. provided by OSCORE.
TODO: explain the rationale for the nonces construction, and the The use of nonces during the OSCORE Setup Section 4.3 prevents the
security implications for Man-in-the-Middle attacks. reuse of AEAD nonces in the RS Security Context, in case the RS loses
the Security Context associated with a client (e.g. in case of
unplanned reboot) and receives a replayed access token. In fact, by
using random nonces as ID Context, the POST /auth-info request
results in a different Security Context, since Master Secret, Sender
ID and Recipient ID are the same but ID Context is different.
Therefore, the main requirement for the nonces is that they have a
good amount of randomness. Moreover, the client echoes the nonce
created by the RS, which verifies it before deriving the Security
Context, and this protects against an adversary acting as a Man-in-
the-Middle and substituting the nonce in transit from client to RS to
provoke the creation of different Security Contexts in the client and
RS.
This profiles recommends that the RS maintains a single access token
for a client. The use of multiple access tokens for a single client
increases the strain on the resource server as it must consider every
access token and calculate the actual permissions of the client.
Also, tokens may contradict each other which may lead the server to
enforce wrong permissions. If one of the access tokens expires
earlier than others, the resulting permissions may offer insufficient
protection. Developers should avoid using multiple access tokens for
a client.
7. Privacy Considerations 7. Privacy Considerations
TBD. This document specifies a profile for the Authentication and
Authorization for Constrained Environments (ACE) framework
[I-D.ietf-ace-oauth-authz]. Thus the general privacy considerations
from the framework also apply to this profile.
As this document uses OSCORE, thus the privacy considerations from
[I-D.ietf-core-object-security] apply here as well.
An unprotected response to an unauthorized request may disclose
information about the resource server and/or its existing
relationship with the client. It is advisable to include as little
information as possible in an unencrypted response. When an OSCORE
Security Context already exists between the client and the resource
server, more detailed information may be included.
Note that some information might still leak after OSCORE is
established, due to observable message sizes, the source, and the
destination addresses.
8. IANA Considerations 8. IANA Considerations
Note to RFC Editor: Please replace all occurrences of "[[this Note to RFC Editor: Please replace all occurrences of "[[this
specification]]" with the RFC number of this specification and delete specification]]" with the RFC number of this specification and delete
this paragraph. this paragraph.
The following registration is done for the ACE OAuth Profile Registry The following registration is done for the ACE OAuth Profile Registry
following the procedure specified in section 8.6 of following the procedure specified in section 8.7 of
[I-D.ietf-ace-oauth-authz]: [I-D.ietf-ace-oauth-authz]:
o Profile name: coap_oscore o Profile name: coap_oscore
o Profile Description: Profile for using OSCORE to secure o Profile Description: Profile for using OSCORE to secure
communication between constrained nodes using the Authentication communication between constrained nodes using the Authentication
and Authorization for Constrained Environments framework. and Authorization for Constrained Environments framework.
o Profile ID: TBD (value between 1 and 255) o Profile ID: TBD (value between 1 and 255)
o Change Controller: IESG o Change Controller: IESG
o Specification Document(s): [[this specification]] o Specification Document(s): [[this specification]]
skipping to change at page 16, line 28 skipping to change at page 18, line 26
9.1. Normative References 9.1. Normative References
[I-D.ietf-ace-oauth-authz] [I-D.ietf-ace-oauth-authz]
Seitz, L., Selander, G., Wahlstroem, E., Erdtman, S., and Seitz, L., Selander, G., Wahlstroem, E., Erdtman, S., and
H. Tschofenig, "Authentication and Authorization for H. Tschofenig, "Authentication and Authorization for
Constrained Environments (ACE) using the OAuth 2.0 Constrained Environments (ACE) using the OAuth 2.0
Framework (ACE-OAuth)", draft-ietf-ace-oauth-authz-15 Framework (ACE-OAuth)", draft-ietf-ace-oauth-authz-15
(work in progress), September 2018. (work in progress), September 2018.
[I-D.ietf-ace-oauth-params]
Seitz, L., "Additional OAuth Parameters for Authorization
in Constrained Environments (ACE)", draft-ietf-ace-oauth-
params-00 (work in progress), September 2018.
[I-D.ietf-core-object-security] [I-D.ietf-core-object-security]
Selander, G., Mattsson, J., Palombini, F., and L. Seitz, Selander, G., Mattsson, J., Palombini, F., and L. Seitz,
"Object Security for Constrained RESTful Environments "Object Security for Constrained RESTful Environments
(OSCORE)", draft-ietf-core-object-security-15 (work in (OSCORE)", draft-ietf-core-object-security-15 (work in
progress), August 2018. progress), August 2018.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
skipping to change at page 18, line 34 skipping to change at page 20, line 38
asymmetric) is used to authenticate the messages in EDHOC, then the asymmetric) is used to authenticate the messages in EDHOC, then the
AS MUST provision the following data, in response to the access token AS MUST provision the following data, in response to the access token
request: request:
o a symmetric or public key (associated to the RS) o a symmetric or public key (associated to the RS)
o a key identifier; o a key identifier;
How these parameters are communicated depends on the type of key How these parameters are communicated depends on the type of key
(asymmetric or symmetric). Moreover, the AS MUST signal the use of (asymmetric or symmetric). Moreover, the AS MUST signal the use of
OSCORE + EDHOC with the 'profile' parameter set to OSCORE + EDHOC with the 'profile' parameter set to
"coap_oscore_edhoc" and follow Appendix B to derive the security "coap_oscore_edhoc".
context to run OSCORE.
Note that in the case described in this section, the 'expires_in' Note that in the case described in this section, the 'expires_in'
parameter, defined in Section 4.2.2. of [RFC6749] defines the parameter, defined in Section 4.2.2. of [RFC6749] defines the
lifetime in seconds of both the access token and the shared secret. lifetime in seconds of both the access token and the shared secret.
After expiration, C MUST acquire a new access token from the AS, and After expiration, C MUST acquire a new access token from the AS, and
run EDHOC again, as specified in this section run EDHOC again, as specified in this section
B.1. Using Asymmetric Keys B.1. Using Asymmetric Keys
In case of an asymmetric key, C MUST communicate its own asymmetric In case of an asymmetric key, C MUST communicate its own asymmetric
key to the AS in the 'cnf' parameter of the access token request, as key to the AS in the 'req_cnf' parameter of the access token request,
specified in Section 5.6.1 of [I-D.ietf-ace-oauth-authz]; the AS MUST as specified in Section 3.1 of [I-D.ietf-ace-oauth-params]; the AS
communicate the RS's public key to C in the response, in the 'rs_cnf' MUST communicate the RS's public key to C in the response, in the
parameter, as specified in Section 5.6.1 of 'rs_cnf' parameter, as specified in Section 3.2 of
[I-D.ietf-ace-oauth-authz]. Note that the RS's public key MUST [I-D.ietf-ace-oauth-params]. Note that the RS's public key MUST
include a 'kid' parameter, and that the value of the 'kid' MUST be include a 'kid' parameter, and that the value of the 'kid' MUST be
included in the access token, to let the RS know which of its public included in the access token, to let the RS know which of its public
keys C used. If the access token is a CWT [RFC8392], the key keys C used. If the access token is a CWT [RFC8392], the key
identifier MUST be placed directly in the 'cnf' structure (if the key identifier MUST be placed directly in the 'cnf' structure (if the key
is only referenced). is only referenced).
Figure 3 shows an example of such a request in CBOR diagnostic Figure 3 shows an example of such a request in CBOR diagnostic
notation without tag and value abbreviations. notation without tag and value abbreviations.
Header: POST (Code=0.02) Header: POST (Code=0.02)
Uri-Host: "server.example.com" Uri-Host: "server.example.com"
Uri-Path: "token" Uri-Path: "token"
Content-Type: "application/cose+cbor" Content-Type: "application/cose+cbor"
Payload: Payload:
{ {
"grant_type" : "client_credentials", "grant_type" : "client_credentials",
"cnf" : { "req_cnf" : {
"COSE_Key" : { "COSE_Key" : {
"kid" : "client_key" "kid" : "client_key"
"kty" : "EC", "kty" : "EC",
"crv" : "P-256", "crv" : "P-256",
"x" : b64'usWxHK2PmfnHKwXPS54m0kTcGJ90UiglWiGahtagnv8', "x" : b64'usWxHK2PmfnHKwXPS54m0kTcGJ90UiglWiGahtagnv8',
"y" : b64'IBOL+C3BttVivg+lSreASjpkttcsz+1rb7btKLv8EX4' "y" : b64'IBOL+C3BttVivg+lSreASjpkttcsz+1rb7btKLv8EX4'
} }
} }
} }
skipping to change at page 20, line 30 skipping to change at page 22, line 30
} }
} }
} }
Figure 4: Example AS response (EDHOC+OSCORE, asymmetric). Figure 4: Example AS response (EDHOC+OSCORE, asymmetric).
B.2. Using Symmetric Keys B.2. Using Symmetric Keys
In the case of a symmetric key, the AS MUST communicate the key to In the case of a symmetric key, the AS MUST communicate the key to
the client in the 'cnf' parameter of the access token response, as the client in the 'cnf' parameter of the access token response, as
specified in Section 5.6.2. of [I-D.ietf-ace-oauth-authz]. AS MUST specified in Section 3.2. of [I-D.ietf-ace-oauth-params]. The AS
also select a key identifier, that MUST be included as the 'kid' MUST also select a key identifier, that MUST be included as the 'kid'
parameter either directly in the 'cnf' structure, as in figure 4 of parameter of the COSE_key, as in figure 9 of
[I-D.ietf-ace-oauth-authz], or as the 'kid' parameter of the [I-D.ietf-ace-oauth-authz].
COSE_key, as in figure 6 of [I-D.ietf-ace-oauth-authz].
Figure 5 shows an example of the necessary parameters in the AS Figure 5 shows an example of the necessary parameters in the AS
response to the access token request when EDHOC is used. The example response to the access token request when EDHOC is used. The example
uses CBOR diagnostic notation without tag and value abbreviations. uses CBOR diagnostic notation without tag and value abbreviations.
Header: Created (Code=2.01) Header: Created (Code=2.01)
Content-Type: "application/cose+cbor" Content-Type: "application/cose+cbor"
Payload: Payload:
{ {
"access_token" : b64'SlAV32hkKG ... "access_token" : b64'SlAV32hkKG ...
skipping to change at page 21, line 51 skipping to change at page 23, line 51
"kty" : "Symmetric", "kty" : "Symmetric",
"kid" : b64'5tOS+h42dkw', "kid" : b64'5tOS+h42dkw',
"k" : b64'+a+Dg2jjU+eIiOFCa9lObw' "k" : b64'+a+Dg2jjU+eIiOFCa9lObw'
} }
} }
Figure 6: Example CWT with EDHOC+OSCORE, symmetric case. Figure 6: Example CWT with EDHOC+OSCORE, symmetric case.
All other parameters defining OSCORE security context are derived All other parameters defining OSCORE security context are derived
from EDHOC message exchange, including the master secret (see from EDHOC message exchange, including the master secret (see
Appendix C.2 of [I-D.selander-ace-cose-ecdhe]). Appendix D.2 of [I-D.selander-ace-cose-ecdhe]).
B.3. Processing B.3. Processing
To provide forward secrecy and mutual authentication in the case of To provide forward secrecy and mutual authentication in the case of
pre-shared keys, pre-established raw public keys or with X.509 pre-shared keys, pre-established raw public keys or with X.509
certificates it is RECOMMENDED to use EDHOC certificates it is RECOMMENDED to use EDHOC
[I-D.selander-ace-cose-ecdhe] to generate the keying material. EDHOC [I-D.selander-ace-cose-ecdhe] to generate the keying material. EDHOC
MUST be used as defined in Appendix C of MUST be used as defined in Appendix D of
[I-D.selander-ace-cose-ecdhe], with the following additions and [I-D.selander-ace-cose-ecdhe], with the following additions and
modifications. modifications.
The first EDHOC message is sent after the access token is posted to The first EDHOC message is sent after the access token is posted to
the /authz-info resource of the RS as specified in Section 5.8.1 of the /authz-info resource of the RS as specified in Section 5.8.1 of
[I-D.ietf-ace-oauth-authz]. Then the EDHOC message_1 is sent and the [I-D.ietf-ace-oauth-authz]. Then the EDHOC message_1 is sent and the
EDHOC protocol is initiated [I-D.selander-ace-cose-ecdhe]). EDHOC protocol is initiated [I-D.selander-ace-cose-ecdhe]).
Before the RS continues with the EDHOC protocol and responds to this Before the RS continues with the EDHOC protocol and responds to this
token submission request, additional verifications on the access token submission request, additional verifications on the access
token are done: the RS SHALL process the access token according to token are done: the RS SHALL process the access token according to
[I-D.ietf-ace-oauth-authz]. If the token is valid then the RS [I-D.ietf-ace-oauth-authz]. If the token is valid then the RS
continues processing EDHOC following Appendix C of continues processing EDHOC following Appendix D of
[I-D.selander-ace-cose-ecdhe], otherwise it discontinues EDHOC and [I-D.selander-ace-cose-ecdhe], otherwise it discontinues EDHOC and
responds with the error code as specified in responds with the error code as specified in
[I-D.ietf-ace-oauth-authz]. [I-D.ietf-ace-oauth-authz].
o In case the EDHOC verification fails, the RS MUST return an error o In case the EDHOC verification fails, the RS MUST return an error
response to the client with code 4.01 (Unauthorized). response to the client with code 4.01 (Unauthorized).
o If RS has an access token for C but not for the resource that C o If RS has an access token for C but not for the resource that C
has requested, RS MUST reject the request with a 4.03 (Forbidden). has requested, RS MUST reject the request with a 4.03 (Forbidden).
o If RS has an access token for C but it does not cover the action C o If RS has an access token for C but it does not cover the action C
requested on the resource, RS MUST reject the request with a 4.05 requested on the resource, RS MUST reject the request with a 4.05
skipping to change at page 23, line 48 skipping to change at page 25, line 48
|<---------+ CoAP response + |<---------+ CoAP response +
| OSCORE | Object-Security option | OSCORE | Object-Security option
| response | | response |
| | | |
Figure 7: Access token and key establishment with EDHOC Figure 7: Access token and key establishment with EDHOC
Acknowledgments Acknowledgments
The authors wish to thank Jim Schaad and Marco Tiloca for the input The authors wish to thank Jim Schaad and Marco Tiloca for the input
on this memo. The error responses specified in Appendix B.3 were on this memo.
originally specified by Gerdes et al. in
[I-D.gerdes-ace-dcaf-authorize].
Authors' Addresses Authors' Addresses
Francesca Palombini
Ericsson AB
Email: francesca.palombini@ericsson.com
Ludwig Seitz Ludwig Seitz
RISE SICS AB RISE SICS AB
Scheelevagen 17 Scheelevagen 17
Lund 22370 Lund 22370
Sweden Sweden
Email: ludwig.seitz@ri.se Email: ludwig.seitz@ri.se
Francesca Palombini Goeran Selander
Ericsson AB Ericsson AB
Farogatan 6
Kista SE-16480 Stockholm
Sweden
Email: francesca.palombini@ericsson.com Email: goran.selander@ericsson.com
Martin Gunnarsson Martin Gunnarsson
RISE SICS AB RISE SICS AB
Scheelevagen 17 Scheelevagen 17
Lund 22370 Lund 22370
Sweden Sweden
Email: martin.gunnarsson@ri.se Email: martin.gunnarsson@ri.se
Goeran Selander
Ericsson AB
Farogatan 6
Kista SE-16480 Stockholm
Sweden
Email: goran.selander@ericsson.com
 End of changes. 62 change blocks. 
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