OAuth Working Group J. Richer
Internet-Draft The MITRE Corporation
Intended status: Standards Track M. Jones
Expires: August 10, 2014 Microsoft
J. Bradley
Ping Identity
M. Machulak
Newcastle University
P. Hunt
Oracle Corporation
February 6, 2014

OAuth 2.0 Dynamic Client Registration Management Protocol
draft-ietf-oauth-dyn-reg-management-00

Abstract

This specification defines methods for management of dynamic OAuth 2.0 client registrations.

Status of This Memo

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

Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet-Drafts is at http://datatracker.ietf.org/drafts/current/.

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This Internet-Draft will expire on August 10, 2014.

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Table of Contents

1. Introduction

In order for an OAuth 2.0 client to utilize an OAuth 2.0 authorization server, the client needs specific information to interact with the server, including an OAuth 2.0 Client ID to use at that server. The OAuth 2.0 Dynamic Client Registration Core Protocol [OAuth.Registration] specification describes how an OAuth 2.0 client can be dynamically registered with an authorization server to obtain this information and how metadata about the client can be registered with the server.

This specification extends the core registration specification by defining a set of methods for management of dynamic OAuth 2.0 client registrations beyond those defined in the core registration specification.

1.1. Notational Conventions

The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL', 'SHALL NOT', 'SHOULD', 'SHOULD NOT', 'RECOMMENDED', 'MAY', and 'OPTIONAL' in this document are to be interpreted as described in [RFC2119].

Unless otherwise noted, all the protocol parameter names and values are case sensitive.

1.2. Terminology

This specification uses the terms "Access Token", "Refresh Token", "Authorization Code", "Authorization Grant", "Authorization Server", "Authorization Endpoint", "Client", "Client Identifier", "Client Secret", "Protected Resource", "Resource Owner", "Resource Server", "Response Type", and "Token Endpoint" defined by OAuth 2.0 [RFC6749] and the terms defined by the OAuth 2.0 Client Dynamic Registration Core Protocol [OAuth.Registration].

This specification defines the following terms:

Client Configuration Endpoint
OAuth 2.0 endpoint through which registration information for a registered client can be managed. This URL for this endpoint is returned by the authorization server in the client information response.
Registration Access Token
OAuth 2.0 bearer token issued by the authorization server through the client registration endpoint that is used to authenticate the caller when accessing the client's registration information at the client configuration endpoint. This access token is associated with a particular registered client.

1.3. Protocol Flow

This extends the flow in the OAuth 2.0 Dynamic Client Registration Core Protocol [OAuth.Registration] specification as follows:

     +--------(A)- Initial Access Token (OPTIONAL)
     |
     |   +----(B)- Software Statement (OPTIONAL) 
     |   |
     v   v
 +-----------+                                      +---------------+
 |           |--(C)- Client Registration Request -->|    Client     |
 |           |                                      | Registration  |
 |           |<-(D)- Client Information Response ---|   Endpoint    |
 |           |                                      +---------------+
 |           |
 |           |                                      +---------------+
 | Client or |--(E)- Read or Update Request ------->|               |
 | Developer |                                      |               |
 |           |<-(F)- Client Information Response ---|    Client     |
 |           |                                      | Configuration |
 |           |                                      |   Endpoint    |
 |           |                                      |               |
 |           |--(G)- Delete Request --------------->|               |
 |           |                                      |               |
 |           |<-(H)- Delete Confirmation -----------|               |
 +-----------+                                      +---------------+

Figure 1: Abstract Extended Dynamic Client Registration Flow

The abstract OAuth 2.0 client dynamic registration flow illustrated in Figure 1 describes the interaction between the client or developer and the endpoints defined in this specification and its parent. This figure does not demonstrate error conditions. This flow includes the following steps:

(A)
Optionally, the client or developer is issued an initial access token for use with the client registration endpoint. The method by which the initial access token is issued to the client or developer is out of scope for this specification.
(B)
Optionally, the client or developer is issued a software statement for use with the client registration endpoint. The method by which the software statement is issued to the client or developer is out of scope for this specification.
(C)
The client or developer calls the client registration endpoint with its desired registration metadata, optionally including the initial access token from (A) if one is required by the authorization server.
(D)
The authorization server registers the client and returns the client's registered metadata, a client identifier that is unique at the server, a set of client credentials such as a client secret if applicable for this client, a URI pointing to the client configuration endpoint, and a registration access token to be used when calling the client configuration endpoint.
(E)
The client or developer optionally calls the client configuration endpoint with a read or update request using the registration access token issued in (D). An update request contains all of the client's registered metadata.
(F)
The authorization server responds with the client's current configuration, potentially including a new registration access token and a new set of client credentials such as a client secret if applicable for this client. If a new registration access token is issued, it replaces the token issued in (D) for all subsequent calls to the client configuration endpoint.
(G)
The client or developer optionally calls the client configuration endpoint with a delete request using the registration access token issued in (D).
(H)
The authorization server deprovisions the client and responds with a confirmation that the deletion has taken place.

1.4. Registration Tokens and Client Credentials

Throughout the course of the dynamic registration protocol, there are three different classes of credentials in play, each with different properties and targets.

1.4.1. Credential Rotation

The Authorization Server MAY rotate the client's registration access token and/or client credentials (such as a client_secret) throughout the lifetime of the client. The client can discovery that these values have changed by reading the client information response returned from either a read or update request to the client configuration endpoint. The client's current registration access token and client credentials (if applicable) MUST be included in this response.

The registration access token SHOULD be rotated only in response to an update request to the client configuration endpoint, at which point the new registration access token is returned to the client and the old registration access token SHOULD be discarded by both parties. If the registration access token were to expire or be rotated outside of such requests, the client or developer might be locked out of managing the client's configuration.

2. Client Configuration Endpoint

The client configuration endpoint is an OAuth 2.0 protected resource that is provisioned by the server to facilitate viewing, updating, and deleting a client's registered information. The location of this endpoint is communicated to the client through the registration_client_uri member of the Client Information Response, as specified in Section 3.1. The client MUST use its registration access token in all calls to this endpoint as an OAuth 2.0 Bearer Token [RFC6750].

Operations on this endpoint are switched through the use of different HTTP methods [RFC2616]. If an authorization server does not support a particular method on the client configuration endpoint, it MUST respond with the appropriate error code.

2.1. Forming the Client Configuration Endpoint URL

The authorization server MUST provide the client with the fully qualified URL in the registration_client_uri element of the Client Information Response, as specified in Section 3.1. The authorization server MUST NOT expect the client to construct or discover this URL on its own. The client MUST use the URL as given by the server and MUST NOT construct this URL from component pieces.

Depending on deployment characteristics, the client configuration endpoint URL may take any number of forms. It is RECOMMENDED that this endpoint URL be formed through the use of a server-constructed URL string which combines the client registration endpoint's URL and the issued client_id for this client, with the latter as either a path parameter or a query parameter. For example, a client with the client identifier s6BhdRkqt3 could be given a client configuration endpoint URL of https://server.example.com/register/s6BhdRkqt3 (path parameter) or of https://server.example.com/register?client_id=s6BhdRkqt3 (query parameter). In both of these cases, the client simply uses the URL as given by the authorization server.

These common patterns can help the server to more easily determine the client to which the request pertains, which MUST be matched against the client to which the registration access token was issued. If desired, the server MAY simply return the client registration endpoint URL as the client configuration endpoint URL and change behavior based on the authentication context provided by the registration access token.

2.2. Client Read Request

To read the current configuration of the client on the authorization server, the client makes an HTTP GET request to the client configuration endpoint, authenticating with its registration access token. This operation SHOULD be idempotent -- not causing changes to the client configuration.

Following is a non-normative example request (with line wraps for display purposes only):

  GET /register/s6BhdRkqt3 HTTP/1.1
  Accept: application/json
  Host: server.example.com
  Authorization: Bearer reg-23410913-abewfq.123483

Upon successful read of the information for a currently active client, the authorization server responds with an HTTP 200 OK with content type of application/json and a payload, as described in Section 3.1. Some values in the response, including the client_secret and registration_access_token, MAY be different from those in the initial registration response. However, since read operations are intended to be idempotent, the read request itself SHOULD NOT cause changes to the client's registered metadata values. If the authorization server includes a new client secret and/or registration access token in its response, the client MUST immediately discard its previous client secret and/or registration access token. The value of the client_id MUST NOT change from the initial registration response.

If the registration access token used to make this request is not valid, the server MUST respond with an error as described in OAuth Bearer Token Usage [RFC6750].

If the client does not exist on this server, the server MUST respond with HTTP 401 Unauthorized and the registration access token used to make this request SHOULD be immediately revoked.

If the client does not have permission to read its record, the server MUST return an HTTP 403 Forbidden.

2.3. Client Update Request

This operation updates a previously-registered client with new metadata at the authorization server. This request is authenticated by the registration access token issued to the client.

The client sends an HTTP PUT to the client configuration endpoint with a content type of application/json. The HTTP entity payload is a JSON [RFC4627] document consisting of a JSON object and all parameters as top- level members of that JSON object.

This request MUST include all client metadata fields as returned to the client from a previous registration, read, or update operation. The client MUST NOT include the registration_access_token, registration_client_uri, client_secret_expires_at, or client_id_issued_at fields described in Section 3.1.

Valid values of client metadata fields in this request MUST replace, not augment, the values previously associated with this client. Omitted fields MUST be treated as null or empty values by the server.

The client MUST include its client_id field in the request, and it MUST be the same as its currently-issued client identifier. If the client includes the client_secret field in the request, the value of this field MUST match the currently-issued client secret for that client. The client MUST NOT be allowed to overwrite its existing client secret with its own chosen value.

For all metadata fields, the authorization server MAY replace any invalid values with suitable default values, and it MUST return any such fields to the client in the response.

For example, a client could send the following request to the client registration endpoint to update the client registration in the above example with new information:

Following is a non-normative example request (with line wraps for display purposes only):

  PUT /register/s6BhdRkqt3 HTTP/1.1
  Accept: application/json
  Host: server.example.com
  Authorization: Bearer reg-23410913-abewfq.123483

  {
   "client_id":"s6BhdRkqt3",
   "client_secret": "cf136dc3c1fc93f31185e5885805d",
   "redirect_uris":[
     "https://client.example.org/callback",
     "https://client.example.org/alt"],
   "scope": "read write dolphin",
   "grant_types": ["authorization_code", "refresh_token"],
   "token_endpoint_auth_method": "client_secret_basic",
   "jwks_uri": "https://client.example.org/my_public_keys.jwks",
   "client_name":"My New Example",
   "client_name#fr":"Mon Nouvel Exemple",
   "logo_uri":"https://client.example.org/newlogo.png",
   "logo_uri#fr":"https://client.example.org/fr/newlogo.png"
  }

This example uses client metadata values defined both in [OAuth.Registration] and [OAuth.Registration.Metadata].

Upon successful update, the authorization server responds with an HTTP 200 OK Message with content type application/json and a payload, as described in Section 3.1. Some values in the response, including the client_secret and registration_access_token, MAY be different from those in the initial registration response. If the authorization server includes a new client secret and/or registration access token in its response, the client MUST immediately discard its previous client secret and/or registration access token. The value of the client_id MUST NOT change from the initial registration response.

If the registration access token used to make this request is not valid, the server MUST respond with an error as described in OAuth Bearer Token Usage [RFC6750].

If the client does not exist on this server, the server MUST respond with HTTP 401 Unauthorized, and the registration access token used to make this request SHOULD be immediately revoked.

If the client is not allowed to update its records, the server MUST respond with HTTP 403 Forbidden.

If the client attempts to set an invalid metadata field and the authorization server does not set a default value, the authorization server responds with an error as described in [OAuth.Registration].

2.4. Client Delete Request

To deprovision itself on the authorization server, the client makes an HTTP DELETE request to the client configuration endpoint. This request is authenticated by the registration access token issued to the client.

Following is a non-normative example request (with line wraps for display purposes only):

  DELETE /register/s6BhdRkqt3 HTTP/1.1
  Host: server.example.com
  Authorization: Bearer reg-23410913-abewfq.123483

A successful delete action will invalidate the client_id, client_secret, and registration_access_token for this client, thereby preventing the client_id from being used at either the authorization endpoint or token endpoint of the authorization server. The authorization server SHOULD immediately invalidate all existing authorization grants and currently-active tokens associated with this client.

If a client has been successfully deprovisioned, the authorization server responds with an HTTP 204 No Content message.

If the server does not support the delete method, the server MUST respond with an HTTP 405 Not Supported.

If the registration access token used to make this request is not valid, the server MUST respond with an error as described in OAuth Bearer Token Usage [RFC6750].

If the client does not exist on this server, the server MUST respond with HTTP 401 Unauthorized and the registration access token used to make this request SHOULD be immediately revoked.

If the client is not allowed to delete itself, the server MUST respond with HTTP 403 Forbidden.

Following is a non-normative example response:

  HTTP/1.1 204 No Content
  Cache-Control: no-store
  Pragma: no-cache

3. Responses

In response to certain requests from the client to either the client registration endpoint or the client configuration endpoint as described in this specification, the authorization server sends the following response bodies.

3.1. Client Information Response

This specification extends the client information response defined in OAuth 2.0 Core Client Dynamic Registration. The response contains the client identifier as well as the client secret, if the client is a confidential client. The response also contains the fully qualified URL of the client configuration endpoint for this specific client that the client may use to obtain and update information about itself. The response also contains a registration access token that is to be used by the client to perform subsequent operations at the client configuration endpoint.

client_id
REQUIRED. The unique client identifier, MUST NOT be currently valid for any other registered client.
client_secret
OPTIONAL. The client secret. If issued, this MUST be unique for each client_id. This value is used by confidential clients to authenticate to the token endpoint as described in OAuth 2.0 [RFC6749] Section 2.3.1.
client_id_issued_at
OPTIONAL. Time at which the Client Identifier was issued. The time is represented as the number of seconds from 1970-01-01T0:0:0Z as measured in UTC until the date/time.
client_secret_expires_at
REQUIRED if client_secret is issued. Time at which the client_secret will expire or 0 if it will not expire. The time is represented as the number of seconds from 1970-01-01T0:0:0Z as measured in UTC until the date/time.
registration_access_token
REQUIRED. Access token that is used at the client configuration endpoint to perform subsequent operations upon the client registration.
registration_client_uri

REQUIRED. The fully qualified URL of the client configuration endpoint for this client. The client MUST use this URL as given when communicating with the client configuration endpoint.

Additionally, the Authorization Server MUST return all registered metadata about this client, including any fields provisioned by the authorization server itself. The authorization server MAY reject or replace any of the client's requested metadata values submitted during the registration or update requests and substitute them with suitable values.

The response is an application/json document with all parameters as top-level members of a JSON object [RFC4627].

Following is a non-normative example response:

  HTTP/1.1 200 OK
  Content-Type: application/json
  Cache-Control: no-store
  Pragma: no-cache

  {
   "registration_access_token": "reg-23410913-abewfq.123483",
   "registration_client_uri": 
      "https://server.example.com/register/s6BhdRkqt3",
   "client_id":"s6BhdRkqt3",
   "client_secret": "cf136dc3c1fc93f31185e5885805d",
   "client_id_issued_at":2893256800,
   "client_secret_expires_at":2893276800,
   "client_name":"My Example Client",
   "client_name#ja-Jpan-JP":
      "\u30AF\u30E9\u30A4\u30A2\u30F3\u30C8\u540D",
   "redirect_uris":[
     "https://client.example.org/callback",
     "https://client.example.org/callback2"],
   "scope": "read write dolphin",
   "grant_types": ["authorization_code", "refresh_token"],
   "token_endpoint_auth_method": "client_secret_basic",
   "logo_uri": "https://client.example.org/logo.png",
   "jwks_uri": "https://client.example.org/my_public_keys.jwks"
  }

4. IANA Considerations

This specification makes no requests of IANA.

5. Security Considerations

While the client secret can expire, the registration access token should not expire while a client is still actively registered. If this token were to expire, a developer or client could be left in a situation where they have no means of retrieving or updating the client's registration information. Were that the case, a new registration would be required, thereby generating a new client identifier. However, to limit the exposure surface of the registration access token, the registration access token MAY be rotated when the developer or client does an update operation on the client's client configuration endpoint. As the registration access tokens are relatively long-term credentials, and since the registration access token is a Bearer token and acts as the sole authentication for use at the client configuration endpoint, it MUST be protected by the developer or client as described in OAuth 2.0 Bearer Token Usage [RFC6750].

Since the client configuration endpoint is an OAuth 2.0 protected resource, it SHOULD have some rate limiting on failures to prevent the registration access token from being disclosed though repeated access attempts.

If a client is deprovisioned from a server, any outstanding registration access token for that client MUST be invalidated at the same time. Otherwise, this can lead to an inconsistent state wherein a client could make requests to the client configuration endpoint where the authentication would succeed but the action would fail because the client is no longer valid. To prevent accidental disclosure from such an erroneous situation, the authorization server MUST treat all such requests as if the registration access token was invalid (by returning an HTTP 401 Unauthorized error, as described).

6. References

6.1. Normative References

[OAuth.Registration] Richer, J., Jones, M., Bradley, J., Machulak, M. and P. Hunt, "OAuth 2.0 Dynamic Client Registration Core Protocol", Internet-Draft draft-ietf-oauth-dyn-reg, February 2014.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., Masinter, L., Leach, P. and T. Berners-Lee, "Hypertext Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.
[RFC4627] Crockford, D., "The application/json Media Type for JavaScript Object Notation (JSON)", RFC 4627, July 2006.
[RFC6749] Hardt, D., "The OAuth 2.0 Authorization Framework", RFC 6749, October 2012.
[RFC6750] Jones, M. and D. Hardt, "The OAuth 2.0 Authorization Framework: Bearer Token Usage", RFC 6750, October 2012.

6.2. Informative References

[OAuth.Registration.Metadata] Richer, J., Jones, M., Bradley, J., Machulak, M. and P. Hunt, "OAuth 2.0 Dynamic Client Registration Metadata", Internet-Draft draft-ietf-oauth-dyn-reg-metadata, February 2014.

Appendix A. Acknowledgments

The authors thank the OAuth Working Group, the User-Managed Access Working Group, and the OpenID Connect Working Group participants for their input to this document. In particular, the following individuals have been instrumental in their review and contribution to various versions of this document: Amanda Anganes, Derek Atkins, Tim Bray, Domenico Catalano, Donald Coffin, Vladimir Dzhuvinov, George Fletcher, Thomas Hardjono, Phil Hunt, William Kim, Torsten Lodderstedt, Eve Maler, Josh Mandel, Nov Matake, Tony Nadalin, Nat Sakimura, Christian Scholz, and Hannes Tschofenig.

Appendix B. Document History

[[ to be removed by the RFC editor before publication as an RFC ]]

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Authors' Addresses

Justin Richer The MITRE Corporation EMail: jricher@mitre.org
Michael B. Jones Microsoft EMail: mbj@microsoft.com URI: http://self-issued.info/
John Bradley Ping Identity EMail: ve7jtb@ve7jtb.com
Maciej Machulak Newcastle University EMail: m.p.machulak@ncl.ac.uk URI: http://ncl.ac.uk/
Phil Hunt Oracle Corporation EMail: phil.hunt@yahoo.com