OAuth 2.0 Dynamic Client Registration Management Protocol
draft-ietf-oauth-dyn-reg-management-13

quot;, RFC 7231, June 2014.

   [TLS.BCP]  Sheffer, Y., Holz, R., and P. Saint-Andre,
              "Recommendations for Secure Use of TLS and DTLS", November
              2014.

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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.  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.

   o  The initial access token is optionally used by the client or
      developer at the registration endpoint.  This is an OAuth 2.0
      token that is used to authorize the initial client registration
      request.  The content, structure, generation, and validation of
      this token are out of scope for this specification.  The
      authorization server can use this token to verify that the
      presenter is allowed to dynamically register new clients.  This
      token may be shared among multiple instances of a client to allow
      them to each register separately, thereby letting the
      authorization server use this token to tie multiple instances of
      registered clients (each with their own distinct client
      identifier) back to the party to whom the initial access token was
      issued, usually an application developer.  This token is usually
      intended to be used only at the client registration endpoint.

   o  The registration access token is used by the client or developer
      at the client configuration endpoint and represents the holder's
      authorization to manage the registration of a client.  This is an
      OAuth 2.0 bearer token that is issued from the client registration
      endpoint in response to a client registration request and is
      returned in a client information response.  The registration
      access token is uniquely bound to the client identifier and is
      required to be presented with all calls to the client
      configuration endpoint.  The registration access token should be
      protected as described in [RFC6750] and should not be shared
      between instances of a client.  If a registration access token is
      shared between client instances, one instance could change or
      delete registration values for all other instances of the client.
      The registration access token can be rotated through the use of
      the client read or update method on the client configuration

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      endpoint.  The registration access token is intended to be used
      only at the client configuration endpoint.

   o  The client credentials (such as "client_secret") are optional
      depending on the type of client and are used to retrieve OAuth
      tokens.  Client credentials are most often bound to particular
      instances of a client and should not be shared between instances.
      Note that since not all types of clients have client credentials,
      they cannot be used to manage client registrations at the client
      configuration endpoint.  The client credentials can be rotated
      through the use of the client read or update method on the client
      configuration endpoint.  The client credentials are intended to be
      used only at the token endpoint.

B.1.  Credential Rotation

   The authorization server may be configured to issue new registration
   access tokens and/or client credentials (such as a "client_secret")
   throughout the lifetime of the client.  This may help minimize the
   impact of exposed credentials.  The authorization server conveys new
   registration access tokens and client credentials (if applicable) to
   the client in the client information response of 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 the client information response.

   The registration access token SHOULD be rotated only in response to a
   read or 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 MUST be discarded by the client and
   SHOULD be discarded by the server, if possible.  If instead the
   registration access token were to expire or be invalidated outside of
   such requests, the client or developer might be locked out of
   managing the client's configuration.

   Note that the authorization server decides the frequency of the
   credential rotation and not the client.  Methods by which the client
   can request credential rotation are outside the scope of this
   document.

Appendix C.  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.  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.

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   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.

Appendix D.  Document History

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

   -13

   o  Changed rate-limiting suggestion to a complexity requirement.

   -12

   o  Used consistent registry name.

   -11

   o  Fixed a series of nits from Peter Yee's Gen-ART review.

   -10

   o  Updated author information.

   o  Updated TLS information, imported from Dynamic Registration core.

   o  Expanded introduction.

   o  Reformatted diagram text.

   o  Added privacy considerations section.

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   -09

   o  Updated author information.

   -08

   o  Updated HTTP RFC reference.

   -07

   o  Editorial clarifications due to document shepherd feedback.

   -06

   o  Removed TLS 1.0.

   o  Moved several explanatory sections to the appendix.

   o  Clarified read operations.

   o  Added IANA request.

   -05

   o  Removed Phil Hunt from authors list, per request.

   o  Applied various minor editorial changes from working group
      comments.

   -04

   o  Incorrect XML uploaded for -03

   -03

   o  Changed draft to be Experimental instead of Standards Track.

   -02

   o  Added more context information to the abstract.

   -01

   o  Addressed issues that arose from last call comments on draft-ietf-
      oauth-dyn-reg and draft-ietf-oauth-dyn-reg-metadata.

   -00

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   o  Created from draft-jones-oauth-dyn-reg-management-00.

Authors' Addresses

   Justin Richer (editor)

   Email: ietf@justin.richer.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: maciej.machulak@gmail.com

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