draft-ietf-ace-oauth-params-13.txt   draft-ietf-ace-oauth-params-14.txt 
ACE Working Group L. Seitz ACE Working Group L. Seitz
Internet-Draft Combitech Internet-Draft Combitech
Intended status: Standards Track April 29, 2020 Intended status: Standards Track March 25, 2021
Expires: October 31, 2020 Expires: September 26, 2021
Additional OAuth Parameters for Authorization in Constrained Additional OAuth Parameters for Authorization in Constrained
Environments (ACE) Environments (ACE)
draft-ietf-ace-oauth-params-13 draft-ietf-ace-oauth-params-14
Abstract Abstract
This specification defines new parameters and encodings for the OAuth This specification defines new parameters and encodings for the OAuth
2.0 token and introspection endpoints when used with the framework 2.0 token and introspection endpoints when used with the framework
for authentication and authorization for constrained environments for authentication and authorization for constrained environments
(ACE). These are used to express the proof-of-possession key the (ACE). These are used to express the proof-of-possession key the
client wishes to use, the proof-of-possession key that the client wishes to use, the proof-of-possession key that the
Authorization Server has selected, and the key the Resource Server Authorization Server has selected, and the key the Resource Server
uses to authenticate to the client. uses to authenticate to the client.
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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
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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 October 31, 2020. This Internet-Draft will expire on September 26, 2021.
Copyright Notice Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the Copyright (c) 2021 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
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the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
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The Authentication and Authorization for Constrained Environments The Authentication and Authorization for Constrained Environments
(ACE) specification [I-D.ietf-ace-oauth-authz] requires some new (ACE) specification [I-D.ietf-ace-oauth-authz] requires some new
parameters for interactions with the OAuth 2.0 [RFC6749] token and parameters for interactions with the OAuth 2.0 [RFC6749] token and
introspection endpoints, as well as some new claims to be used in introspection endpoints, as well as some new claims to be used in
access tokens. These parameters and claims can also be used in other access tokens. These parameters and claims can also be used in other
contexts and have therefore been put into a dedicated document, to contexts and have therefore been put into a dedicated document, to
facilitate their use in a manner independent of facilitate their use in a manner independent of
[I-D.ietf-ace-oauth-authz]. [I-D.ietf-ace-oauth-authz].
Note that although all examples are shown in Concise Binary Object Note that although all examples are shown in Concise Binary Object
Respresentation (CBOR) [RFC7049], JSON [RFC8259] MAY be used as an Representation (CBOR) [RFC8949], JSON [RFC8259] MAY be used as an
alternative for HTTP-based communications, as specified in alternative for HTTP-based communications, as specified in
[I-D.ietf-ace-oauth-authz]. [I-D.ietf-ace-oauth-authz].
2. Terminology 2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP "OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
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This section defines the "req_cnf" parameter allowing clients to This section defines the "req_cnf" parameter allowing clients to
request a specific proof-of-possession key in an access token from a request a specific proof-of-possession key in an access token from a
token endpoint in the ACE framework [I-D.ietf-ace-oauth-authz]: token endpoint in the ACE framework [I-D.ietf-ace-oauth-authz]:
req_cnf req_cnf
OPTIONAL. This field contains information about the key the OPTIONAL. This field contains information about the key the
client would like to bind to the access token for proof-of- client would like to bind to the access token for proof-of-
possession. It is RECOMMENDED that an AS reject a request possession. It is RECOMMENDED that an AS reject a request
containing a symmetric key value in the 'req_cnf' field containing a symmetric key value in the 'req_cnf' field
(kty=Symmetric), since the AS is expected to be able to generate (kty=Symmetric), since the AS is expected to be able to generate
better symmetric keys than a constrained client. The AS MUST better symmetric keys than a constrained client (Note: this does
verify that the client really is in possession of the not apply to key identifiers referencing a symmetric key). The AS
corresponding key. Values of this parameter follow the syntax and MUST verify that the client really is in possession of the
semantics of the "cnf" claim either from section 3.1 of corresponding key. Profiles of [I-D.ietf-ace-oauth-authz] using
[I-D.ietf-ace-cwt-proof-of-possession] for CBOR-based interactions this specification MUST define the proof-of-possession method used
or from section 3.1 of [RFC7800] for JSON-based interactions. by the AS, if they allow clients to use this request parameter.
Values of this parameter follow the syntax and semantics of the
"cnf" claim either from section 3.1 of [RFC8747] for CBOR-based
interactions or from section 3.1 of [RFC7800] for JSON-based
interactions.
Figure 1 shows a request for an access token using the "req_cnf" Figure 1 shows a request for an access token using the "req_cnf"
parameter to request a specific public key as proof-of-possession parameter to request a specific public key as proof-of-possession
key. The content is displayed in CBOR diagnostic notation, without key. The content is displayed in CBOR diagnostic notation, without
abbreviations and with line-breaks for better readability. abbreviations and with line-breaks for better readability.
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"
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3.2. AS-to-Client Response 3.2. AS-to-Client Response
This section defines the following additional parameters for an AS This section defines the following additional parameters for an AS
response to a request to the token endpoint: response to a request to the token endpoint:
cnf cnf
REQUIRED if the token type is "pop" and a symmetric key is used. REQUIRED if the token type is "pop" and a symmetric key is used.
MAY be present for asymmetric proof-of-possession keys. This MAY be present for asymmetric proof-of-possession keys. This
field contains the proof-of-possession key that the AS selected field contains the proof-of-possession key that the AS selected
for the token. Values of this parameter follow the syntax and for the token. Values of this parameter follow the syntax and
semantics of the "cnf" claim either from section 3.1 of semantics of the "cnf" claim either from section 3.1 of [RFC8747]
[I-D.ietf-ace-cwt-proof-of-possession] for CBOR-based interactions for CBOR-based interactions or from section 3.1 of [RFC7800] for
of from section 3.1 of [RFC7800] for JSON-based interactions. See JSON-based interactions. See Section 5 for additional discussion
Section 5 for additional discussion of the usage of this of the usage of this parameter.
parameter.
rs_cnf rs_cnf
OPTIONAL if the token type is "pop" and asymmetric keys are used. OPTIONAL if the token type is "pop" and asymmetric keys are used.
MUST NOT be present otherwise. This field contains information MUST NOT be present otherwise. This field contains information
about the public key used by the RS to authenticate. If this about the public key used by the RS to authenticate. If this
parameter is absent, either the RS does not use a public key or parameter is absent, either the RS does not use a public key or
the AS knows that the RS can authenticate itself to the client the AS knows that the RS can authenticate itself to the client
without additional information. Values of this parameter follow without additional information. Values of this parameter follow
the syntax and semantics of the "cnf" claim either from section the syntax and semantics of the "cnf" claim either from section
3.1 of [I-D.ietf-ace-cwt-proof-of-possession] for CBOR-based 3.1 of [RFC8747] for CBOR-based interactions or from section 3.1
interactions or from section 3.1 of [RFC7800] for JSON-based of [RFC7800] for JSON-based interactions. See Section 5 for
interactions. See Section 5 for additional discussion of the additional discussion of the usage of this parameter.
usage of this parameter.
Figure 2 shows an AS response containing a token and a "cnf" Figure 2 shows an AS response containing a token and a "cnf"
parameter with a symmetric proof-of-possession key. parameter with a symmetric proof-of-possession key.
Header: Created (Code=2.01) Header: Created (Code=2.01)
Content-Format: "application/ace+cbor" Content-Format: "application/ace+cbor"
Payload: Payload:
{ {
"access_token" : h'4A5015DF686428 ... "access_token" : h'4A5015DF686428 ...
(remainder of CWT omitted for brevity; (remainder of CWT omitted for brevity;
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} }
} }
} }
Figure 3: Example AS response, including the RS's public key. Figure 3: Example AS response, including the RS's public key.
4. Parameters for the Introspection Endpoint 4. Parameters for the Introspection Endpoint
This section defines the use of CBOR instead of JSON for the "cnf" This section defines the use of CBOR instead of JSON for the "cnf"
introspection response parameter specified in section 9.4 of introspection response parameter specified in section 9.4 of
[I-D.ietf-oauth-mtls]. [RFC8705].
If CBOR is used instead of JSON in an interaction with the If CBOR is used instead of JSON in an interaction with the
introspection endpoint, the AS MUST use the parameter mapping introspection endpoint, the AS MUST use the parameter mapping
specified in Figure 5 and the value must follow the syntax of "cnf" specified in Figure 5 and the value must follow the syntax of "cnf"
claim values from section 3.1 of claim values from section 3.1 of [RFC8747].
[I-D.ietf-ace-cwt-proof-of-possession].
Figure 4 shows an AS response to an introspection request including Figure 4 shows an AS response to an introspection request including
the "cnf" parameter to indicate the proof-of-possession key bound to the "cnf" parameter to indicate the proof-of-possession key bound to
the token. the token.
Header: Created Code=2.01) Header: Created (Code=2.01)
Content-Format: "application/ace+cbor" Content-Format: "application/ace+cbor"
Payload: Payload:
{ {
"active" : true, "active" : true,
"scope" : "read", "scope" : "read",
"aud" : "tempSensor4711", "aud" : "tempSensor4711",
"cnf" : { "cnf" : {
"COSE_Key" : { "COSE_Key" : {
"kty" : "EC2", "kty" : "EC2",
"kid" : h'11', "kid" : h'11',
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"y" : h'20138BF82DC1B6D562BE0FA54AB7804A3 "y" : h'20138BF82DC1B6D562BE0FA54AB7804A3
A64B6D72CCFED6B6FB6ED28BBFC117E' A64B6D72CCFED6B6FB6ED28BBFC117E'
} }
} }
} }
Figure 4: Example introspection response. Figure 4: Example introspection response.
5. Confirmation Method Parameters 5. Confirmation Method Parameters
The confirmation method parameters are used as follows: The confirmation method parameters are used in
[I-D.ietf-ace-oauth-authz] as follows:
o "req_cnf" in the access token request C -> AS, OPTIONAL to o "req_cnf" in the access token request C -> AS, OPTIONAL to
indicate the client's raw public key, or the key-identifier of a indicate the client's raw public key, or the key-identifier of a
previously established key between C and RS that the client wishes previously established key between C and RS that the client wishes
to use for proof-of-possession of the access token. to use for proof-of-possession of the access token.
o "cnf" in the token response AS -> C, OPTIONAL if using an o "cnf" in the token response AS -> C, OPTIONAL if using an
asymmetric key or a key that the client requested via a key asymmetric key or a key that the client requested via a key
identifier in the request. REQUIRED if the client didn't specify identifier in the request. REQUIRED if the client didn't specify
a "req_cnf" and symmetric keys are used. Used to indicate the a "req_cnf" and symmetric keys are used. Used to indicate the
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o "rs_cnf" in the token response AS -> C, OPTIONAL to indicate the o "rs_cnf" in the token response AS -> C, OPTIONAL to indicate the
public key of the RS, if it uses one to authenticate itself to the public key of the RS, if it uses one to authenticate itself to the
client and the binding between key and RS identity is not client and the binding between key and RS identity is not
established through other means. established through other means.
Note that the COSE_Key structure in a confirmation claim or parameter Note that the COSE_Key structure in a confirmation claim or parameter
may contain an "alg" or "key_ops" parameter. If such parameters are may contain an "alg" or "key_ops" parameter. If such parameters are
present, a client MUST NOT use a key that is incompatible with the present, a client MUST NOT use a key that is incompatible with the
profile or proof-of-possession algorithm according to those profile or proof-of-possession algorithm according to those
parameters. An RS MUST reject a proof-of-possession using such a parameters. An RS MUST reject a proof-of-possession using such a key
key. with a response code equivalent to the CoAP code 4.00 (Bad Request).
If an access token is issued for an audience that includes several If an access token is issued for an audience that includes several
RS, the "rs_cnf" parameter MUST NOT be used, since the client cannot RS, the "rs_cnf" parameter MUST NOT be used, since the client cannot
determine for which RS the key applies. This document recommends to determine for which RS the key applies. This document recommends to
specify a different endpoint that the client can use to acquire RS specify a different endpoint that the client can use to acquire RS
authentication keys in such cases. The specification of such an authentication keys in such cases. The specification of such an
endpoint is out of scope for this document. endpoint is out of scope for this document.
6. CBOR Mappings 6. CBOR Mappings
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Special thanks to Brian Campbell for his thorough review of this Special thanks to Brian Campbell for his thorough review of this
document. document.
Ludwig Seitz worked on this document as part of the CelticNext Ludwig Seitz worked on this document as part of the CelticNext
projects CyberWI, and CRITISEC with funding from Vinnova. projects CyberWI, and CRITISEC with funding from Vinnova.
12. References 12. References
12.1. Normative References 12.1. Normative References
[I-D.ietf-ace-cwt-proof-of-possession]
Jones, M., Seitz, L., Selander, G., Erdtman, S., and H.
Tschofenig, "Proof-of-Possession Key Semantics for CBOR
Web Tokens (CWTs)", draft-ietf-ace-cwt-proof-of-
possession-11 (work in progress), October 2019.
[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-33 Framework (ACE-OAuth)", draft-ietf-ace-oauth-authz-38
(work in progress), February 2020. (work in progress), March 2021.
[I-D.ietf-oauth-mtls]
Campbell, B., Bradley, J., Sakimura, N., and T.
Lodderstedt, "OAuth 2.0 Mutual-TLS Client Authentication
and Certificate-Bound Access Tokens", draft-ietf-oauth-
mtls-17 (work in progress), August 2019.
[IANA.OAuthParameters] [IANA.OAuthParameters]
IANA, "OAuth Parameters", IANA, "OAuth Parameters",
<https://www.iana.org/assignments/oauth-parameters/oauth- <https://www.iana.org/assignments/oauth-parameters/oauth-
parameters.xhtml#parameters>. parameters.xhtml#parameters>.
[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>.
[RFC6749] Hardt, D., Ed., "The OAuth 2.0 Authorization Framework", [RFC6749] Hardt, D., Ed., "The OAuth 2.0 Authorization Framework",
RFC 6749, DOI 10.17487/RFC6749, October 2012, RFC 6749, DOI 10.17487/RFC6749, October 2012,
<https://www.rfc-editor.org/info/rfc6749>. <https://www.rfc-editor.org/info/rfc6749>.
[RFC7049] Bormann, C. and P. Hoffman, "Concise Binary Object
Representation (CBOR)", RFC 7049, DOI 10.17487/RFC7049,
October 2013, <https://www.rfc-editor.org/info/rfc7049>.
[RFC7800] Jones, M., Bradley, J., and H. Tschofenig, "Proof-of- [RFC7800] Jones, M., Bradley, J., and H. Tschofenig, "Proof-of-
Possession Key Semantics for JSON Web Tokens (JWTs)", Possession Key Semantics for JSON Web Tokens (JWTs)",
RFC 7800, DOI 10.17487/RFC7800, April 2016, RFC 7800, DOI 10.17487/RFC7800, April 2016,
<https://www.rfc-editor.org/info/rfc7800>. <https://www.rfc-editor.org/info/rfc7800>.
[RFC8152] Schaad, J., "CBOR Object Signing and Encryption (COSE)", [RFC8152] Schaad, J., "CBOR Object Signing and Encryption (COSE)",
RFC 8152, DOI 10.17487/RFC8152, July 2017, RFC 8152, DOI 10.17487/RFC8152, July 2017,
<https://www.rfc-editor.org/info/rfc8152>. <https://www.rfc-editor.org/info/rfc8152>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8259] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data [RFC8259] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
Interchange Format", STD 90, RFC 8259, Interchange Format", STD 90, RFC 8259,
DOI 10.17487/RFC8259, December 2017, DOI 10.17487/RFC8259, December 2017,
<https://www.rfc-editor.org/info/rfc8259>. <https://www.rfc-editor.org/info/rfc8259>.
[RFC8705] Campbell, B., Bradley, J., Sakimura, N., and T.
Lodderstedt, "OAuth 2.0 Mutual-TLS Client Authentication
and Certificate-Bound Access Tokens", RFC 8705,
DOI 10.17487/RFC8705, February 2020,
<https://www.rfc-editor.org/info/rfc8705>.
[RFC8747] Jones, M., Seitz, L., Selander, G., Erdtman, S., and H.
Tschofenig, "Proof-of-Possession Key Semantics for CBOR
Web Tokens (CWTs)", RFC 8747, DOI 10.17487/RFC8747, March
2020, <https://www.rfc-editor.org/info/rfc8747>.
[RFC8949] Bormann, C. and P. Hoffman, "Concise Binary Object
Representation (CBOR)", STD 94, RFC 8949,
DOI 10.17487/RFC8949, December 2020,
<https://www.rfc-editor.org/info/rfc8949>.
12.2. Informative References 12.2. Informative References
[RFC7252] Shelby, Z., Hartke, K., and C. Bormann, "The Constrained [RFC7252] Shelby, Z., Hartke, K., and C. Bormann, "The Constrained
Application Protocol (CoAP)", RFC 7252, Application Protocol (CoAP)", RFC 7252,
DOI 10.17487/RFC7252, June 2014, DOI 10.17487/RFC7252, June 2014,
<https://www.rfc-editor.org/info/rfc7252>. <https://www.rfc-editor.org/info/rfc7252>.
Author's Address Author's Address
Ludwig Seitz Ludwig Seitz
Combitech Combitech
Djaeknegatan 31 Djaeknegatan 31
Malmoe 211 35 Malmoe 211 35
Sweden Sweden
Email: ludwig.seitz@combitech.se Email: ludwig.seitz@combitech.se
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