Reciprical OAuth
draft-hardt-oauth-mutual-01

Abstract

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. Reciprical OAuth enables a more seemless experience for the user to grant access to a pair of protected resources.

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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.

Reciprical 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”, “SHALL”, “SHALL NOT”, “SHOULD”, “SHOULD NOT”, “RECOMMENDED”, “MAY”, and “OPTIONAL” are to be interpreted as described in BCP 14, RFC 2119 [RFC2119].

2. Reciprical Authorization Flow

The reciprical 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. Reciprical 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:

grant_type REQUIRED. Value MUST be set to “reciprical_authorization_code”. [DH: should this be a URI?]

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 concerns 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
 Host: server.example.com
 Authorization: Basic ej4hsyfishwssjdusisdhkjsdksusdhjkjsdjk
 Content-Type: application/x-www-form-urlencoded

 grant_type=mutual_authorization_code&code=hasdyubasdjahsbdkjbasd&client_id=example.com&access_token=sadadojsadlkjasdkljxxlkjdas

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

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

3. IANA Considerations

TBD.

4. Acknowledgements

TBD.

5. Normative References

Appendix A. Document History

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

• Initial version.

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

• renamed to Reciprical OAuth
• clarified user consent in reciprical flow
• changed authentication to be client authentication per [RFC6749] 2.3

Author's Address

Table of Contents

• 1. Introduction
• 1.1. Terminology
• 2. Reciprical Authorization Flow
• 2.1. User Consent
• 2.2. Reciprical Authorization Code
• 3. IANA Considerations
• 4. Acknowledgements
• 5. Normative References
• Appendix A. Document History
• A.1. draft-hardt-oauth-mutual-00
• A.2. draft-hardt-oauth-mutual-01
• Author's Address