Network Working Group                                           D. Hardt
Internet-Draft                                                    Amazon
Intended status: Informational                          January 16, 2018
Expires: July 20, 2018

                            Reciprocal OAuth


   There are times when a user has a pair of protected resources that
   would like to request access to each other.  While OAuth flows
   typically enable the user to grant a client access to a protected
   resource, granting the inverse access requires an additional flow.
   Reciprocal OAuth enables a more seemless experience for the user to
   grant access to a pair of protected resources.

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   This Internet-Draft will expire on July 20, 2018.

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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

1.  Introduction

   In the usual three legged, authorization code grant, the OAuth flow
   enables a resource owner (user) to enable a client (party A) to be
   granted authorization to access a protected resource (party B).  If
   party A also has a protected resource that the user would like to let
   party B access, then a complete OAuth flow, but in the reverse
   direction, must be performed.

   Reciprocal OAuth enables party A to obtain constent from the user to
   grant access to a protected resource at party A, and to short circuit
   the OAuth flow by passing an authorization code to party B using the
   acces token party A obtained from party B to provide party B the
   context of the user.  This simplifies the user experience for each
   party to obtain acces tokens from the other.

1.1.  Terminology

   In this document, the key words "MUST", "MUST NOT", "REQUIRED",
   and "OPTIONAL" are to be interpreted as described in BCP 14, RFC 2119

2.  Reciprocal Authorization Flow

   The reciprocal authorization flow starts after the client (party A)
   has obtained an access token from the authorization server (party B)
   per [RFC6749] 4.1 Authorization Code Grant.

2.1.  User Consent

   Party A obtains consent from the user to grant access to protected
   resources at party A.  The consent represents the scopes party B had
   preconfigured at party A.

2.2.  Reciprocal Authorization Code

   Party A generates an authorization code representing the access
   granted to party B by the user.  Party A then makes a request to
   party B's token endpoint authenticating per [RFC6749] 2.3 and sending
   the following parameters using the "application/x-www-form-
   urlencoded" format per [RFC6749] Appendix B with a character encoding
   of UTF-8 in the HTTP request entity-body:

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   grant_type REQUIRED.  Value MUST be set to

   code REQUIRED.  The authorization code generated by party A.

   client_id REQUIRED, party A'a client ID.

   access_token REQUIRED, the access token obtained from Party B.  Used
   to provide user context.  [DH: security concern passing the access
   token in the body?]

   For example, the client makes the following HTTP request using TLS
   (with extra line breaks for display purposes only):

 POST /token HTTP/1.1
 Authorization: Basic ej4hsyfishwssjdusisdhkjsdksusdhjkjsdjk
 Content-Type: application/x-www-form-urlencoded


   Party B MUST then verify the access token was granted to the client
   identified by the client_id.

   Party B MUST respond with either an HTTP 200 (OK) response if the
   request is valid, or an HTTP 400 "Bad Request" if it is not.

   Party B then plays the role of the client to make an access token
   request per [RFC6749] 4.1.3.

3.  IANA Considerations


4.  Acknowledgements


5.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,

   [RFC6749]  Hardt, D., Ed., "The OAuth 2.0 Authorization Framework",
              RFC 6749, DOI 10.17487/RFC6749, October 2012,

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   [RFC6750]  Jones, M. and D. Hardt, "The OAuth 2.0 Authorization
              Framework: Bearer Token Usage", RFC 6750,
              DOI 10.17487/RFC6750, October 2012,

Appendix A.  Document History

A.1.  draft-hardt-oauth-mutual-00

   o  Initial version.

A.2.  draft-hardt-oauth-mutual-01

   o  renamed to Reciprocal OAuth

   o  clarified user consent in reciprocal flow

   o  changed authentication to be client authentication per [RFC6749]

A.3.  draft-hardt-oauth-mutual-02

   o  changed grant type to URI

   o  added valid request response codes in 2.2

Author's Address

   Dick Hardt


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