Imported debug from /usr/lib/site-python/debug.pyc draft-ietf-ace-oauth-params-00 - Additional OAuth Parameters for Authorization in Constrained Environments (ACE)
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ACE Working Group                                               L. Seitz
Internet-Draft                                                      RISE
Intended status: Standards Track                      September 18, 2018
Expires: March 22, 2019


      Additional OAuth Parameters for Authorization in Constrained
                           Environments (ACE)
                     draft-ietf-ace-oauth-params-00

Abstract

   This specification defines new parameters for the OAuth 2.0 token and
   introspection endpoints when used with framework for authentication
   and authorization for constrained environments (ACE).  These are used
   to express the desired audience of a requested access token, the
   desired proof-of-possession key, the proof-of-possession key that the
   AS has selected, and the key the RS should use to authenticate to the
   client.

Status of This Memo

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   This Internet-Draft will expire on March 22, 2019.

Copyright Notice

   Copyright (c) 2018 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   2
   3.  Parameters for the Token Endpoint . . . . . . . . . . . . . .   3
     3.1.  Client-to-AS Request  . . . . . . . . . . . . . . . . . .   3
     3.2.  AS-to-Client Response . . . . . . . . . . . . . . . . . .   3
   4.  Parameters for the Introspection Endpoint . . . . . . . . . .   4
     4.1.  AS-to-RS Response . . . . . . . . . . . . . . . . . . . .   4
   5.  Confirmation Method Parameters  . . . . . . . . . . . . . . .   4
   6.  CBOR Mappings . . . . . . . . . . . . . . . . . . . . . . . .   5
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   8.  Privacy Considerations  . . . . . . . . . . . . . . . . . . .   5
   9.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
     9.1.  OAuth Parameter Registration  . . . . . . . . . . . . . .   6
     9.2.  OAuth Introspection Response Parameter Registration . . .   6
   10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .   6
   11. Normative References  . . . . . . . . . . . . . . . . . . . .   7
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   8

1.  Introduction

   The Authorization for the Internet of Things specification
   [I-D.ietf-ace-oauth-authz] requires some new parameters for requests
   and responses to the OAuth 2.0 [RFC6749] token and introspection
   endpoints, as well as some new claims to be used in access tokens.
   This document specifies these new parameters and claims separately
   from the framework, so they can be used and updated independently.

2.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

   Readers are assumed to be familiar with the terminology from
   [I-D.ietf-ace-oauth-authz].

   Note that the term "endpoint" is used here following its OAuth 2.0
   [RFC6749] definition, which is to denote resources such as token and
   introspection at the AS and authz-info at the RS.  The CoAP [RFC7252]




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   definition, which is "An entity participating in the CoAP protocol"
   is not used in this specification.

3.  Parameters for the Token Endpoint

3.1.  Client-to-AS Request

   This document defines the following additional parameters for
   requesting an access token from a token endpoint in the ACE framework
   [I-D.ietf-ace-oauth-authz]:

   req_aud
      OPTIONAL.  Specifies the audience for which the client is
      requesting an access token.  If this parameter is missing, it is
      assumed that the AS has a default audience for access tokens
      issued to this client.  If a client submits a request for an
      access token without specifying a "req_aud" parameter, and the AS
      does not have a default audience value for this client, then the
      AS MUST respond with an error message using a response code
      equivalent to the CoAP response code 4.00 (Bad Request).

   req_cnf
      OPTIONAL.  This field contains information about the key the
      client would like to bind to the access token for proof-of-
      possession.  It is RECOMMENDED that an AS reject a request
      containing a symmetric key value in the 'req_cnf' field, since the
      AS is expected to be able to generate better symmetric keys than a
      potentially constrained client.  See Section 5 for more details on
      the use of this parameter.

3.2.  AS-to-Client Response

   This document defines the following additional parameters for an AS
   response to a request to the token endpoint:

   cnf
      REQUIRED if the token type is "pop" and a symmetric key is used.
      MAY be present for asymmetric proof-of-possession keys.  This
      field contains the proof-of-possession key that the AS selected
      for the token.  See Section 5 for details on the use of this
      parameter.

   rs_cnf
      OPTIONAL if the token type is "pop" and asymmetric keys are used.
      MUST NOT be present otherwise.  This field contains information
      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




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      the AS assumes that the client already knows the public key of the
      RS.  See Section 5 for details on the use of this parameter.

4.  Parameters for the Introspection Endpoint

4.1.  AS-to-RS Response

   This document defines the following additional parameters for an AS
   response to a request to the introspection endpoint:

   cnf
      OPTIONAL.  This field contains information about the proof-of-
      possession key that binds the client to the access token.  See
      Section 5 for more details on the use of the "cnf" parameter.

   rs_cnf
      OPTIONAL.  If the RS has several keys it can use to authenticate
      towards the client, the AS can give the RS a hint using this
      parameter, as to which key it should use (e.g., if the AS
      previously informed the client about a public key the RS is
      holding).  See Section 5 for more details on the use of this
      parameter.

5.  Confirmation Method Parameters

   The confirmation method parameters are used as follows:

   o  "req_cnf" in the token request C -> AS, OPTIONAL to indicate the
      client's raw public key, or the key-identifier of a previously
      established key between C and RS that the client wishes to use for
      proof-of-possession of the access token.
   o  "cnf" in the token response AS -> C, OPTIONAL if using an
      asymmetric key or a key that the client requested via a key
      identifier in the request.  REQUIRED if the client didn't specify
      a "req_cnf" and symmetric keys are used.  Used to indicate the
      symmetric key generated by the AS for proof-of-possession of the
      access token.
   o  "cnf" in the introspection response AS -> RS, REQUIRED if the
      token that was subject to introspection is a proof-of-possession
      token, absent otherwise.  Indicates the proof-of-possession key
      bound to the token.
   o  "rs_cnf" in the token response AS -> C, OPTIONAL to indicate the
      public key of the RS if it has one.
   o  "rs_cnf" in the introspection response AS -> RS, OPTIONAL to
      indicate to the RS which asymmetric key pair to use for
      authenticating to the client if the RS has several public keys.





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   All confirmation parameters use the same formatting and semantics as
   the "cnf" claim specified in [I-D.ietf-ace-cwt-proof-of-possession]
   when used with a CBOR encoding.  When these parameters are used with
   a JSON encoding, the formatting and semantics of the "cnf" claim
   specified in [RFC7800] is used.

   Note that the COSE_Key structure in a confirmation claim or parameter
   may contain an "alg" or "key_ops" parameter.  If such parameters are
   present, a client MUST NOT use a key that is not compatible with the
   profile or proof-of-possession algorithm according to those
   parameters.  An RS MUST reject a proof-of-possession using such a
   key.

   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
   determine for which RS the key applies.  This document recommends to
   specify a different endpoint that the client can use to acquire RS
   authentication keys in such cases.  The specification of such an
   endpoint is out of scope for this document.

6.  CBOR Mappings

   If CBOR is used, the new parameters and claims defined in this
   document MUST be mapped to CBOR types as specified in Figure 1, using
   the given integer abbreviation for the map key.

       /-----------------+----------+----------------------------------\
       | Parameter name  | CBOR Key | Value Type                       |
       |-----------------+----------+----------------------------------|
       | cnf             |  8       | map                              |
       | rs_cnf          | 17       | map                              |
       | req_aud         | 18       | text string                      |
       | req_cnf         | 19       | map                              |
       \-----------------+----------+----------------------------------/

                Figure 1: CBOR mappings for new parameters.

7.  Security Considerations

   This document is an extension to [I-D.ietf-ace-oauth-authz].  All
   security considerations from that document apply here as well.

8.  Privacy Considerations

   This document is an extension to [I-D.ietf-ace-oauth-authz].  All
   privacy considerations from that document apply here as well.





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9.  IANA Considerations

9.1.  OAuth Parameter Registration

   This section registers the following parameters in the "OAuth
   Parameters" registry [IANA.OAuthParameters]:

   o  Name: "req_aud"
   o  Parameter Usage Location: authorization request, token request
   o  Change Controller: IESG
   o  Reference: Section 3.1 of [this document]

   o  Name: "req_cnf"
   o  Parameter Usage Location: token request
   o  Change Controller: IESG
   o  Reference: Section 5 of [this document]

   o  Name: "rs_cnf"
   o  Parameter Usage Location: token response
   o  Change Controller: IESG
   o  Reference: Section 5 of [this document]

   o  Name: "cnf"
   o  Parameter Usage Location: token response
   o  Change Controller: IESG
   o  Reference: Section 5 of [this document]

9.2.  OAuth Introspection Response Parameter Registration

   This section registers the following parameters in the OAuth Token
   Introspection Response registry [IANA.TokenIntrospectionResponse].

   o  Name: "cnf"
   o  Description: Key to prove the right to use a PoP token.
   o  Change Controller: IESG
   o  Reference: Section 4.1 of [this document]

   o  Name: "rs_cnf"
   o  Description: The key the RS should use to authenticate to the
      client.
   o  Change Controller: IESG
   o  Reference: Section 4.1 of [this document]

10.  Acknowledgments

   This document is a product of the ACE working group of the IETF.





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   Ludwig Seitz worked on this document as part of the CelticPlus
   project CyberWI, with funding from Vinnova.

11.  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-03 (work in progress), June 2018.

   [I-D.ietf-ace-oauth-authz]
              Seitz, L., Selander, G., Wahlstroem, E., Erdtman, S., and
              H. Tschofenig, "Authentication and Authorization for
              Constrained Environments (ACE) using the OAuth 2.0
              Framework (ACE-OAuth)", draft-ietf-ace-oauth-authz-13
              (work in progress), July 2018.

   [IANA.OAuthParameters]
              IANA, "OAuth Parameters",
              <https://www.iana.org/assignments/oauth-parameters/oauth-
              parameters.xhtml#parameters>.

   [IANA.TokenIntrospectionResponse]
              IANA, "OAuth Token Introspection Response",
              <https://www.iana.org/assignments/oauth-parameters/oauth-
              parameters.xhtml#token-introspection-response>.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997, <https://www.rfc-
              editor.org/info/rfc2119>.

   [RFC6749]  Hardt, D., Ed., "The OAuth 2.0 Authorization Framework",
              RFC 6749, DOI 10.17487/RFC6749, October 2012,
              <https://www.rfc-editor.org/info/rfc6749>.

   [RFC7252]  Shelby, Z., Hartke, K., and C. Bormann, "The Constrained
              Application Protocol (CoAP)", RFC 7252,
              DOI 10.17487/RFC7252, June 2014, <https://www.rfc-
              editor.org/info/rfc7252>.

   [RFC7800]  Jones, M., Bradley, J., and H. Tschofenig, "Proof-of-
              Possession Key Semantics for JSON Web Tokens (JWTs)",
              RFC 7800, DOI 10.17487/RFC7800, April 2016,
              <https://www.rfc-editor.org/info/rfc7800>.





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   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

Author's Address

   Ludwig Seitz
   RISE
   Scheelevaegen 17
   Lund  223 70
   Sweden

   Email: ludwig.seitz@ri.se






































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