Token Revocation
draft-lodderstedt-oauth-revocation-01

Abstract

This draft proposes an additional endpoint for OAuth authorization servers for revoking tokens.

Status of this Memo

This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.

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This Internet-Draft will expire on July 14, 2011.

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Table of Contents

1.  Introduction
2.  Token Revocation
3.  Acknowledgements
4.  IANA Considerations
5.  Security Considerations
6.  Informative References
§  Authors' Addresses

1.  Introduction

The current OAuth 2.0 draft [draft‑ietf‑oauth‑v2‑11] (Hammer-Lahav, E., Ed., Recordon, D., and D. Hardt, “The OAuth 2.0 Protocol draft-ietf-oauth-v2-11,” December 2010.) defines several ways for a client to obtain refresh and access tokens. This specification supplements the draft with a mechanism to revoke both types of tokens and facilitates the following use cases.

• The end-user triggers revocation from within the client that sends the appropriate revocation request to the autorization server. From the end-user's perspective, this looks like a “logout” or “reset” function. The request causes the removal of the client permissions associated with the particular token to access the end-user’s protected resources. This use case makes it even more comfortable to the end-user to revoke his access grant immediately via the client.
• In contrast to revocation by a client, the authorization server (or a related entity) may offer its end-users a self-care portal to delete access grants given to clients independent of any token storing devices. Such a portal offers the possibility to an end-user to look at and revoke all access grants he once authorized. In cases the token storing device is not available, e.g. it is lost or stolen, revocation by a self-care portal is the only possibility to limit or avoid abuse.

In the end, security, usability, and ease of use are increased by token revocation.

By using an additional endpoint, the token revocation endpoint, clients can request the revocation of a particular token. Compliant implementation MUST support the revocation of refresh tokens, access token revocation MAY be supported.

2.  Token Revocation

The client requests the revocation of a particular token by making an HTTP "POST" request to the token revocation endpoint. The location of the token revocation endpoint can be found in the authorization servers documentation, or can be obtained by using [[OAuth Discovery ]]. The token endpoint URI MAY include a query component.

Since requests to the token revocation endpoint result in the transmission of plain text credentials in the HTTP request, the authorization server MUST require the use of a transport-layer security mechanism when sending requests to the token revocation endpoints. Authorization servers MUST support TLS 1.2 as defined in [RFC5246], and MAY support additional transport-layer security mechanisms.

The client authenticates with the authorization server by adding its client credentials to the request as described in Section 3 of [draft‑ietf‑oauth‑v2‑11] (Hammer-Lahav, E., Ed., Recordon, D., and D. Hardt, “The OAuth 2.0 Protocol draft-ietf-oauth-v2-11,” December 2010.).

The client constructs the request by including the following parameters using the "application/x-www-form-urlencoded" format in the HTTP request entity-body:

token

REQUIRED. The token that the client wants to get revoked.

token_type

REQUIRED. The type of the token to be revoked, either "refresh_token" or "access_token". Information about the supported token types can be found in the authorization server's documentation, or can be obtained by using [[OAuth Discovery ]].

For example, a client may request the revocation of a refresh token with the following request (line breaks are for display purposes only):

     POST /revoke HTTP/1.1
     Host: server.example.com
     Content-Type: application/x-www-form-urlencoded

     token=45ghiukldjahdnhzdauz&token_type=refresh_token&
     client_id=s6BhdRkqt3&client_secret=gX1fBat3bV

The authorization server first verifies whether the client is authorized to revoke the particular token based on the client credentials and its policy. For example, only the client the token has been issued for might be allowed to revoke it. It is also conceivable to allow a dedicated user self-care portal to revoke all kinds of tokens.

In the next step, the authorization server invalidates the token. Whether the revocation takes effect instantly or with some delay depends on the architecture of the particular deployment. The client MUST NOT make any assumptions about the timing and MUST NOT use the token again.

If the processed token is a refresh token and the authorization server supports the revocation of access tokens, then the authorization server MUST also invalidate all access tokens issued for that refresh token.

The authorization server indicates a successful processing of the request by a HTTP status code 204. Status code 401 indicates a failed client authentication, whereas a status code 403 is used if the client is not authorized to revoke the particular token. For all other error conditions, a status code 400 is used along with an error response as defined in section 5.3. of [draft‑ietf‑oauth‑v2‑11] (Hammer-Lahav, E., Ed., Recordon, D., and D. Hardt, “The OAuth 2.0 Protocol draft-ietf-oauth-v2-11,” December 2010.). The following error codes are defined for the token revocation endpoint:

unsupported_token_type

The authorization server does not support the revocation of the presented token type. I.e. the client tried to revoke an access token on a server not supporting this feature.

invalid_token

The presented token is invalid.

3.  Acknowledgements

We would like to thank Sebastian Ebling and Christian Stübner for their valuable feedback.

4.  IANA Considerations

This draft includes no request to IANA.

5.  Security Considerations

All relevant security considerations have been given in the functional specification.

6. Informative References

Authors' Addresses