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Versions: 00 draft-ietf-oauth-dyn-reg

OAuth Working Group                                       J. Richer, Ed.
Internet-Draft                                     The MITRE Corporation
Intended status: Standards Track                              J. Bradley
Expires: February 27, 2014                                 Ping Identity
                                                                M. Jones
                                                               Microsoft
                                                             M. Machulak
                                                    Newcastle University
                                                         August 26, 2013


               OAuth 2.0 Core Dynamic Client Registration
                   draft-richer-oauth-dyn-reg-core-00

Abstract

   This specification defines an endpoint and protocol for dynamic
   registration of OAuth 2.0 clients at an authorization server.

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/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on February 27, 2014.

Copyright Notice

   Copyright (c) 2013 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of



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

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Notational Conventions  . . . . . . . . . . . . . . . . .   3
     1.2.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   3
     1.3.  Protocol Flow . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Client Metadata . . . . . . . . . . . . . . . . . . . . . . .   4
     2.1.  Relationship Between Grant Types and Response Types . . .   6
   3.  Client Registration Endpoint  . . . . . . . . . . . . . . . .   7
     3.1.  Client Registration Request . . . . . . . . . . . . . . .   8
     3.2.  Client Registration Response  . . . . . . . . . . . . . .   9
   4.  Responses . . . . . . . . . . . . . . . . . . . . . . . . . .   9
     4.1.  Client Information Response . . . . . . . . . . . . . . .   9
     4.2.  Client Registration Error Response  . . . . . . . . . . .  10
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  11
     5.1.  OAuth Token Endpoint Authentication Methods Registry  . .  12
       5.1.1.  Registration Template . . . . . . . . . . . . . . . .  12
       5.1.2.  Initial Registry Contents . . . . . . . . . . . . . .  12
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .  13
   7.  Normative References  . . . . . . . . . . . . . . . . . . . .  14
   Appendix A.  Acknowledgments  . . . . . . . . . . . . . . . . . .  15
   Appendix B.  Use Cases  . . . . . . . . . . . . . . . . . . . . .  16
     B.1.  Open Registration . . . . . . . . . . . . . . . . . . . .  17
     B.2.  Stateless Open Registration using JWT . . . . . . . . . .  18
     B.3.  Protected Registration  . . . . . . . . . . . . . . . . .  19
     B.4.  Developer Automation  . . . . . . . . . . . . . . . . . .  20
   Appendix C.  Document History . . . . . . . . . . . . . . . . . .  21
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  24

1.  Introduction

   In some use-case scenarios, it is desirable or necessary to allow
   OAuth 2.0 clients to obtain authorization from an OAuth 2.0
   authorization server without requiring the two parties to interact
   beforehand.  Nevertheless, for the authorization server to accurately
   and securely represent to end-users which client is seeking
   authorization to access the end-user's resources, a method for
   automatic and unique registration of clients is needed.  The OAuth
   2.0 authorization framework does not define how the relationship
   between the client and the authorization server is initialized, or
   how a given client is assigned a unique client identifier.
   Historically, this has happened out-of-band from the OAuth 2.0
   protocol.  This draft provides a mechanism for a client to register
   itself with the authorization server, which can be used to
   dynamically provision a client identifier, and optionally a client



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   secret.  Additionally, the mechanisms in this draft may can be used
   by a client developer to register the client with the authorization
   server in a programmatic fashion.

   As part of the registration process, this specification also defines
   a mechanism for the client to present the authorization server with a
   set of metadata, such as a set of valid redirect URIs.

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",
   and "Token Endpoint" defined by OAuth 2.0 [RFC6749].

   This specification defines the following additional terms:

   Client Registration Endpoint  OAuth 2.0 endpoint through which a
      client can be registered at an authorization server.  The means by
      which the URL for this endpoint are obtained are out of scope for
      this specification.
   Initial Access Token  OAuth 2.0 access token optionally issued by an
      Authorization Server and used to authorize calls to the client
      registration endpoint.  The type and format of this token are
      likely service-specific and are out of scope for this
      specification.  The means by which the authorization server issues
      this token as well as the means by which the registration endpoint
      validates this token are out of scope for this specification.

1.3.  Protocol Flow

          +--------(A)- Initial Access Token
          |
          v
    +-----------+                                      +---------------+
    |           |--(B)- Client Registration Request -->|    Client     |
    | Client or |                                      | Registration  |
    | Developer |<-(C)- Client Information Response ---|   Endpoint    |



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    |           |                                      +---------------+
    +-----------+



   Figure 1: Abstract Protocol Flow


   The abstract OAuth 2.0 Client dynamic registration flow illustrated
   in Figure 1 describes the interaction between the client or developer
   and the endpoint defined in this specification.  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)
      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.
   (C)
      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, and possibly other values.

2.  Client Metadata

   Clients generally have an array of metadata associated with their
   unique client identifier at the authorization server, such as the
   list of valid redirect URIs.

   The client metadata values serve two parallel purposes in the overall
   OAuth 2.0 dynamic client registration protocol:

   o  the client requesting its desired values for each parameter to the
      authorization server in a register (Section 3.1) request, and
   o  the authorization server informing the client of the current
      values of each parameter that the client has been registered to
      use through a client information response (Section 4.1).

   An authorization server MAY override any value that a client requests
   during the registration process (including any omitted values) and
   replace the requested value with a default at the server's



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   discretion.  The authorization server SHOULD provide documentation
   for any fields that it requires to be filled in by the client or to
   have particular values or formats.  An authorization server MAY
   ignore the values provided by the client for any field in this list.

   Extensions and profiles of this specification MAY expand this list,
   and authorization servers MUST accept all fields in this list.  The
   authorization server MUST ignore any additional parameters sent by
   the Client that it does not understand.

   redirect_uris
      Array of redirect URIs for use in redirect-based flows such as the
      authorization code and implicit grant types.  It is RECOMMENDED
      that clients using these flows register this parameter, and an
      authorization server SHOULD require registration of valid redirect
      URIs for all clients that use these grant types to protect against
      token and credential theft attacks.
   token_endpoint_auth_method
      The requested authentication method for the token endpoint.
      Values defined by this specification are:

      *  "none": The client is a public client as defined in OAuth 2.0
         and does not have a client secret.
      *  "client_secret_post": The client uses the HTTP POST parameters
         defined in OAuth 2.0 section 2.3.1.
      *  "client_secret_basic": the client uses HTTP Basic defined in
         OAuth 2.0 section 2.3.1

      Additional values can be defined via the IANA OAuth Token Endpoint
      Authentication Methods Registry Section 5.1.  Absolute URIs can
      also be used as values for this parameter without being
      registered.  If unspecified or omitted, the default is
      "client_secret_basic", denoting HTTP Basic Authentication Scheme
      as specified in Section 2.3.1 of OAuth 2.0.
   grant_types
      Array of OAuth 2.0 grant types that the Client may use.  These
      grant types are defined as follows:

      *  "authorization_code": The Authorization Code Grant described in
         OAuth 2.0 Section 4.1
      *  "implicit": The Implicit Grant described in OAuth 2.0
         Section 4.2
      *  "password": The Resource Owner Password Credentials Grant
         described in OAuth 2.0 Section 4.3
      *  "client_credentials": The Client Credentials Grant described in
         OAuth 2.0 Section 4.4
      *  "refresh_token": The Refresh Token Grant described in OAuth 2.0
         Section 6.



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      *  "urn:ietf:params:oauth:grant-type:jwt-bearer": The JWT Bearer
         Grant defined in OAuth JWT Bearer Token Profiles [OAuth.JWT].
      *  "urn:ietf:params:oauth:grant-type:saml2-bearer": The SAML 2
         Bearer Grant defined in OAuth SAML 2 Bearer Token Profiles
         [OAuth.SAML2].

      Authorization Servers MAY allow for other values as defined in
      grant type extensions to OAuth 2.0.  The extension process is
      described in OAuth 2.0 Section 2.5.  If the token endpoint is used
      in the grant type, the value of this parameter MUST be the same as
      the value of the "grant_type" parameter passed to the token
      endpoint defined in the extension.
   response_types
      Array of the OAuth 2.0 response types that the Client may use.
      These response types are defined as follows:

      *  "code": The Authorization Code response described in OAuth 2.0
         Section 4.1.
      *  "token": The Implicit response described in OAuth 2.0
         Section 4.2.

      Authorization servers MAY allow for other values as defined in
      response type extensions to OAuth 2.0.  The extension process is
      described in OAuth 2.0 Section 2.5.  If the authorization endpoint
      is used by the grant type, the value of this parameter MUST be the
      same as the value of the "response_type" parameter passed to the
      authorization endpoint defined in the extension.

2.1.  Relationship Between Grant Types and Response Types

   The "grant_types" and "response_types" values described above are
   partially orthogonal, as they refer to arguments passed to different
   endpoints in the OAuth protocol.  However, they are related in that
   the "grant_types" available to a client influence the
   "response_types" that the client is allowed to use, and vice versa.
   For instance, a "grant_types" value that includes
   "authorization_code" implies a "response_types" value that includes
   "code", as both values are defined as part of the OAuth 2.0
   authorization code grant.  As such, a server supporting these fields
   SHOULD take steps to ensure that a client cannot register itself into
   an inconsistent state.

   The correlation between the two fields is listed in the table below.

   +-------------------------------------------------+-----------------+
   | grant_types value includes:                     | response_types  |
   |                                                 | value includes: |
   +-------------------------------------------------+-----------------+



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   | authorization_code                              | code            |
   | implicit                                        | token           |
   | password                                        | (none)          |
   | client_credentials                              | (none)          |
   | refresh_token                                   | (none)          |
   | urn:ietf:params:oauth:grant-type:jwt-bearer     | (none)          |
   | urn:ietf:params:oauth:grant-type:saml2-bearer   | (none)          |
   +-------------------------------------------------+-----------------+


   Extensions and profiles of this document that introduce new values to
   either the "grant_types" or "response_types" parameter MUST document
   all correspondences between these two parameter types.

3.  Client Registration Endpoint

   The client registration endpoint is an OAuth 2.0 endpoint defined in
   this document that is designed to allow a client to be registered
   with the authorization server.  The client registration endpoint MUST
   accept HTTP POST messages with request parameters encoded in the
   entity body using the "application/json" format.  The client
   registration endpoint MUST be protected by a transport-layer security
   mechanism, and the server MUST support TLS 1.2 RFC 5246 [RFC5246] and
   /or TLS 1.0 [RFC2246] and MAY support additional transport-layer
   mechanisms meeting its security requirements.  When using TLS, the
   Client MUST perform a TLS/SSL server certificate check, per RFC 6125
   [RFC6125].

   The client registration endpoint MAY be an OAuth 2.0 protected
   resource and accept an initial access token in the form of an OAuth
   2.0 [RFC6749] access token to limit registration to only previously
   authorized parties.  The method by which the initial access token is
   obtained by the registrant is generally out-of-band and is out of
   scope for this specification.  The method by which the initial access
   token is verified and validated by the client registration endpoint
   is out of scope for this specification.

   To support open registration and facilitate wider interoperability,
   the client registration endpoint SHOULD allow initial registration
   requests with no authorization (which is to say, with no OAuth 2.0
   access token in the request).  These requests MAY be rate-limited or
   otherwise limited to prevent a denial-of-service attack on the client
   registration endpoint.

   The client registration endpoint MUST ignore all parameters it does
   not understand.





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3.1.  Client Registration Request

   This operation registers a new client to the authorization server.
   The authorization server assigns this client a unique client
   identifier, optionally assigns a client secret, and associates the
   metadata given in the request with the issued client identifier.  The
   request includes any parameters described in Client Metadata
   (Section 2) that the client wishes to specify for itself during the
   registration.  The authorization server MAY provision default values
   for any items omitted in the client metadata.

   To register, the client or developer sends an HTTP POST to the client
   registration 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.

   For example, if the server supports open registration (with no
   initial access token), the client could send the following
   registration request to the client registration endpoint:

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

   POST /register HTTP/1.1
   Content-Type: application/json
   Accept: application/json
   Host: server.example.com

   {
    "redirect_uris":["https://client.example.org/callback",
       "https://client.example.org/callback2"],
    "token_endpoint_auth_method":"client_secret_basic",
    "scope":"read write dolphin",
    "extension_parameter":"foo"
   }


   Alternatively, if the server supports authorized registration, the
   developer or the client will be provisioned with an initial access
   token (the method by which the initial access token is obtained is
   out of scope for this specification).  The developer or client sends
   the following authorized registration request to the client
   registration endpoint.  Note that the initial access token sent in
   this example as an OAuth 2.0 Bearer Token [RFC6750], but any OAuth
   2.0 token type could be used by an authorization server:

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



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   POST /register HTTP/1.1
   Content-Type: application/json
   Accept: application/json
   Authorization: Bearer ey23f2.adfj230.af32-developer321
   Host: server.example.com

   {
    "redirect_uris":["https://client.example.org/callback",
       "https://client.example.org/callback2"],
    "token_endpoint_auth_method":"client_secret_basic",
    "scope":"read write dolphin",
    "extension_parameter":"foo"
   }


3.2.  Client Registration Response

   Upon successful registration, the authorization server generates a
   new client identifier for the client.  This client identifier MUST be
   unique at the server and MUST NOT be in use by any other client.  The
   server responds with an HTTP 201 Created code and a body of type
   "application/json" with content described in Client Information
   Response (Section 4.1).

   Upon an unsuccessful registration, the authorization server responds
   with an error as described in Client Registration Error
   (Section 4.2).

4.  Responses

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

4.1.  Client Information Response

   The response contains the client identifier as well as the client
   secret, if the client is a confidential client.  The response MAY
   contain additional fields as specified by extensions to this
   specification.

   client_id
      REQUIRED.  The unique client identifier, MUST NOT be currently
      valid for any other registered client.
   client_secret






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      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.

   Additionally, the Authorization Server MUST return all registered
   metadata (Section 2) 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

   {
    "client_id":"s6BhdRkqt3",
    "client_secret": "cf136dc3c1fc93f31185e5885805d",
    "client_id_issued_at":2893256800
    "client_secret_expires_at":2893276800
    "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",
    "extension_parameter": "foo"
   }


4.2.  Client Registration Error Response





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   When an OAuth 2.0 error condition occurs, such as the client
   presenting an invalid initial access token, the authorization server
   returns an error response appropriate to the OAuth 2.0 token type.

   When a registration error condition occurs, the authorization server
   returns an HTTP 400 status code (unless otherwise specified) with
   content type "application/json" consisting of a JSON object [RFC4627]
   describing the error in the response body.

   The JSON object contains two members:

   error
      The error code, a single ASCII string.
   error_description
      A human-readable text description of the error for debugging.

   This specification defines the following error codes:

   invalid_redirect_uri
      The value of one or more "redirect_uris" is invalid.
   invalid_client_metadata
      The value of one of the client metadata (Section 2) fields is
      invalid and the server has rejected this request.  Note that an
      Authorization server MAY choose to substitute a valid value for
      any requested parameter of a client's metadata.

   Following is a non-normative example of an error response (with line
   wraps for display purposes only):

   HTTP/1.1 400 Bad Request
   Content-Type: application/json
   Cache-Control: no-store
   Pragma: no-cache

   {
    "error":"invalid_redirect_uri",
    "error_description":"The redirect URI of http://sketchy.example.com
      is not allowed for this server."
   }


5.  IANA Considerations









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5.1.  OAuth Token Endpoint Authentication Methods Registry

   This specification establishes the OAuth Token Endpoint
   Authentication Methods registry.

   Additional values for use as "token_endpoint_auth_method" metadata
   values are registered with a Specification Required ([RFC5226]) after
   a two-week review period on the oauth-ext-review@ietf.org mailing
   list, on the advice of one or more Designated Experts.  However, to
   allow for the allocation of values prior to publication, the
   Designated Expert(s) may approve registration once they are satisfied
   that such a specification will be published.

   Registration requests must be sent to the oauth-ext-review@ietf.org
   mailing list for review and comment, with an appropriate subject
   (e.g., "Request to register token_endpoint_auth_method value:
   example").

   Within the review period, the Designated Expert(s) will either
   approve or deny the registration request, communicating this decision
   to the review list and IANA.  Denials should include an explanation
   and, if applicable, suggestions as to how to make the request
   successful.

   IANA must only accept registry updates from the Designated Expert(s)
   and should direct all requests for registration to the review mailing
   list.

5.1.1.  Registration Template

   Token Endpoint Authorization Method name:
      The name requested (e.g., "example").  This name is case
      sensitive.  Names that match other registered names in a case
      insensitive manner SHOULD NOT be accepted.

   Change controller:
      For Standards Track RFCs, state "IETF".  For others, give the name
      of the responsible party.  Other details (e.g., postal address,
      email address, home page URI) may also be included.

   Specification document(s):
      Reference to the document(s) that specify the token endpoint
      authorization method, preferably including a URI that can be used
      to retrieve a copy of the document(s).  An indication of the
      relevant sections may also be included but is not required.

5.1.2.  Initial Registry Contents




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   The OAuth Token Endpoint Authentication Methods registry's initial
   contents are:

   o  Token Endpoint Authorization Method name: "none"
   o  Change controller: IETF
   o  Specification document(s): [[ this document ]]

   o  Token Endpoint Authorization Method name: "client_secret_post"
   o  Change controller: IETF
   o  Specification document(s): [[ this document ]]

   o  Token Endpoint Authorization Method name: "client_secret_basic"
   o  Change controller: IETF
   o  Specification document(s): [[ this document ]]

6.  Security Considerations

   Since requests to the client registration endpoint result in the
   transmission of clear-text credentials (in the HTTP request and
   response), the Authorization Server MUST require the use of a
   transport-layer security mechanism when sending requests to the
   registration endpoint.  The server MUST support TLS 1.2 RFC 5246
   [RFC5246] and/or TLS 1.0 [RFC2246] and MAY support additional
   transport-layer mechanisms meeting its security requirements.  When
   using TLS, the Client MUST perform a TLS/SSL server certificate
   check, per RFC 6125 [RFC6125].

   For clients that use redirect-based grant types such as
   "authorization_code" and "implicit", authorization servers SHOULD
   require clients to register their "redirect_uris".  Requiring clients
   to do so can help mitigate attacks where rogue actors inject and
   impersonate a validly registered client and intercept its
   authorization code or tokens through an invalid redirect URI.


















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   Public clients MAY register with an authorization server using this
   protocol, if the authorization server's policy allows them.  Public
   clients use a "none" value for the "token_endpoint_auth_method"
   metadata field and are generally used with the "implicit" grant type.
   Often these clients will be short-lived in-browser applications
   requesting access to a user's resources and access is tied to a
   user's active session at the authorization server.  Since such
   clients often do not have long-term storage, it's possible that such
   clients would need to re-register every time the browser application
   is loaded.  Additionally, such clients may not have ample opportunity
   to unregister themselves using the delete action before the browser
   closes.  To avoid the resulting proliferation of dead client
   identifiers, an authorization server MAY decide to expire
   registrations for existing clients meeting certain criteria after a
   period of time has elapsed.

   Since different OAuth 2.0 grant types have different security and
   usage parameters, an authorization server MAY require separate
   registrations for a piece of software to support multiple grant
   types.  For instance, an authorization server might require that all
   clients using the "authorization_code" grant type make use of a
   client secret for the "token_endpoint_auth_method", but any clients
   using the "implicit" grant type do not use any authentication at the
   token endpoint.  In such a situation, a server MAY disallow clients
   from registering for both the "authorization_code" and "implicit"
   grant types simultaneously.  Similarly, the "authorization_code"
   grant type is used to represent access on behalf of an end user, but
   the "client_credentials" grant type represents access on behalf of
   the client itself.  For security reasons, an authorization server
   could require that different scopes be used for these different use
   cases, and as a consequence it MAY disallow these two grant types
   from being registered together by the same client.  In all of these
   cases, the authorization server would respond with an
   "invalid_client_metadata" error response (Section 4.2).

7.  Normative References

   [IANA.Language]
              Internet Assigned Numbers Authority (IANA), "Language
              Subtag Registry", 2005.

   [JWK]      Jones, M., "JSON Web Key (JWK)", draft-ietf-jose-json-web-
              key (work in progress), May 2013.

   [OAuth.JWT]
              Jones, M., Campbell, B., and C. Mortimore, "JSON Web Token
              (JWT) Bearer Token Profiles for OAuth 2.0", draft-ietf-
              oauth-jwt-bearer (work in progress), March 2013.



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   [OAuth.SAML2]
              Campbell, B., Mortimore, C., and M. Jones, "SAML 2.0
              Bearer Assertion Profiles for OAuth 2.0", draft-ietf-
              oauth-saml2-bearer (work in progress), March 2013.

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

   [RFC2246]  Dierks, T. and C. Allen, "The TLS Protocol Version 1.0",
              RFC 2246, January 1999.

   [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.

   [RFC4122]  Leach, P., Mealling, M., and R. Salz, "A Universally
              Unique IDentifier (UUID) URN Namespace", RFC 4122, July
              2005.

   [RFC4627]  Crockford, D., "The application/json Media Type for
              JavaScript Object Notation (JSON)", RFC 4627, July 2006.

   [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", BCP 26, RFC 5226,
              May 2008.

   [RFC5246]  Dierks, T. and E. Rescorla, "The Transport Layer Security
              (TLS) Protocol Version 1.2", RFC 5246, August 2008.

   [RFC5646]  Phillips, A. and M. Davis, "Tags for Identifying
              Languages", BCP 47, RFC 5646, September 2009.

   [RFC6125]  Saint-Andre, P. and J. Hodges, "Representation and
              Verification of Domain-Based Application Service Identity
              within Internet Public Key Infrastructure Using X.509
              (PKIX) Certificates in the Context of Transport Layer
              Security (TLS)", RFC 6125, March 2011.

   [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.

Appendix A.  Acknowledgments

   The authors thank the OAuth Working Group, the User-Managed Access
   Working Group, and the OpenID Connect Working Group participants for



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   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, Nat Sakimura,
   Christian Scholz, and Hannes Tschofenig.

Appendix B.  Use Cases

   [[ Editor's Note: These are some of the collected use cases that this
   protocol can address, they still need to be refactored into the two
   specifications. ]]

   In the OAuth 2.0 specification [RFC6749], a client is identified by
   its own unique Client identifier ("client_id") at each authorization
   server that it associates with.  Dynamic registration as defined in
   this document is one way for a client to get a client identifier and
   associate a set of metadata with that identifier.  Lack of such a
   client identifier is the expected trigger for a client registration
   operation.

   In many cases, this client identifier is a unique, pairwise
   association between a particular running instance of a piece of
   client software and a particular running instance of an authorization
   server software.  In particular:

   o  A single instance of client software (such as a Web server)
      talking to multiple authorization servers will need to register
      with each authorization server separately, creating a distinct
      client identifier with each authorization server.  The client can
      not make any assumption that the authorization servers are
      correlating separate registrations of the client software together
      without further profiles and extensions to this specification
      document.  The means by which a client discovers and
      differentiates between multiple authorization servers is out of
      scope for this specification.
   o  Multiple instances of client software (such as a native
      application installed on multiple devices simultaneously) talking
      to the same authorization server will need to each register with
      that authorization server separately, creating a distinct client
      identifier for each copy of the application.  The authorization
      server cannot make any assumption of correlation between these
      clients without further specifications, profiles, and extensions
      to this specification.  The client can not make any assumption
      that the authorization server will correlate separate
      registrations of the client software together without further
      profiles and extensions to this specification document.



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   A client identifier (and its associated credentials) could also be
   shared between multiple instances of a client.  Mechanisms for
   sharing client identifiers between multiple instances of a piece of
   software (either client or authorization server) are outside the
   scope of this specification, as it is expected that every successful
   registration request (Section 3.1) results in the issuance of a new
   client identifier.

   There are several patterns of OAuth client registration that dynamic
   registration protocol can enable.  The following non-normative
   example lifecycle descriptions are not intended to be an exhaustive
   list.  It is assumed that the authorization server supports the
   dynamic registration protocol and that all necessary discovery steps
   (which are out of scope for this specification) have already been
   performed.

B.1.  Open Registration

   Open registration, with no authorization required on the client
   registration endpoint, works as follows:

   a.  A client needs to get OAuth 2.0 tokens from an authorization
       server, but the client does not have a client identifier for that
       authorization server.
   b.  The client sends an HTTP POST request to the client registration
       endpoint at the authorization server and includes its metadata.
   c.  The authorization server issues a client identifier and returns
       it to the client along with a registration access token and a
       reference to the client's client configuration endpoint.
   d.  The client stores the returned response from the authorization
       server.  At a minimum, it should remember the values of
       "client_id", "client_secret" (if present),
       "registration_access_token", and "registration_client_uri".
   e.  The client uses the its "client_id" and "client_secret" (if
       provided) to request OAuth 2.0 tokens using any valid OAuth 2.0
       flow for which it is authorized.
   f.  If the client's "client_secret" expires or otherwise stops
       working, the client sends an HTTP GET request to the
       "registration_client_uri" with the "registration_access_token" as
       its authorization.  This response will contain the client's
       refreshed "client_secret" along with any changed metadata values.
       Its "client_id" will remain the same.
   g.  If the client needs to update its configuration on the
       authorization server, it sends an HTTP PUT request to the
       "registration_client_uri" with the "registration_access_token" as
       its authorization.  This response will contain the client's
       changed metadata values.  Its "client_id" will remain the same.




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   h.  If the client is uninstalled or otherwise deprovisioned, it can
       send an HTTP DELETE request to the "registration_client_uri" with
       the "registration_access_token" as its authorization.  This will
       effectively deprovision the client from the authorization server.

B.2.  Stateless Open Registration using JWT

   Open registration, with no authorization required on the client
   registration endpoint.  The registration endpoint/Authorization
   server maintain no state for the client.  All information is storted
   in the client_id that is returned to the client and passed back to
   the Authorization server and Token Endpoint on subsiquent requests.
   If the client is using the implicit flow then the JWT MUST include
   the redirect URI and be signed by the AS for its later consumption.
   If the client is registering it's public key for use in the self
   signed assertion flow, the JWT MUST include the client's public key
   in the signed JWT.  If the client is using a symetric client secret,
   the AS MUST include the secret as a claim in the JWT and encrypt or
   sign and encrypt the token to itself as appropriate.  This method is
   transperent to the client and requires no aditional paramaters.

   The flow works as follows:

   a.  A client needs to get OAuth 2.0 tokens from an authorization
       server, but the client does not have a client identifier for that
       authorization server.
   b.  The client sends an HTTP POST request to the client registration
       endpoint at the authorization server and includes its metadata.
   c.  The authorization server creates a JWE containing the required
       metadata such as redirect_uri and client secret for http basic
       authentication.  (For clients using the assertion flow for
       authentication the registration endpoint can create a JWS
       containing the clients public key)
   d.  The authorization server issues the JWT as the client identifier
       and returns it to the client along with a JWT registration access
       token and a reference to the client's client configuration
       endpoint.  (The client_id cannot be changed currently so updates
       are not possable the registration access token would only allow
       for reads)
   e.  The client stores the returned response from the authorization
       server.  At a minimum, it should remember the values of
       "client_id", "client_secret" (if present),
       "registration_access_token", and "registration_client_uri".
   f.  The client uses the its "client_id" and "client_secret" (if
       provided) to request OAuth 2.0 tokens using any valid OAuth 2.0
       flow for which it is authorized.
   g.  If the client's "client_secret" expires or otherwise stops
       working, the client must re-register.



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B.3.  Protected Registration

   An authorization server may require an initial access token for
   requests to its registration endpoint.  While the method by which a
   client receives this initial Access token and the method by which the
   authorization server validates this initial access token are out of
   scope for this specification, a common approach is for the developer
   to use a manual pre-registration portal at the authorization server
   that issues an initial access token to the developer.  This allows
   the developer to package the initial access token with different
   instances of the client application.  While each copy of the
   application would get its own client identifier (and registration
   access token), all instances of the application would be tied back to
   the developer by their shared use of this initial access token.

   a.  A developer is creating a client to use an authorization server
       and knows that instances of the client will dynamically register
       at runtime, but that the authorization server requires
       authorization at the registration endpoint.
   b.  The developer visits a manual pre-registration page at the
       authorization server and is issued an initial access token in the
       form of an OAuth 2.0 Bearer Token [RFC6750].
   c.  The developer packages that token with all instances of the
       client application.
   d.  The client needs to get OAuth 2.0 tokens from an authorization
       server, but the client does not have a client identifier for that
       authorization server.
   e.  The client sends an HTTP POST request to the client registration
       endpoint at the authorization server with its metadata, and the
       initial access token as its authorization.
   f.  The authorization server issues a client identifier and returns
       it to the client along with a registration access token and a
       reference to the client's client configuration endpoint.
   g.  The client stores the returned response from the authorization
       server.  At a minimum, it should know the values of "client_id",
       "client_secret" (if present), "registration_access_token", and
       "registration_client_uri".
   h.  The client uses the its "client_id" and "client_secret" (if
       provided) to request OAuth 2.0 tokens using any supported OAuth
       2.0 flow for which this client is authorized.
   i.  If the client's "client_secret" expires or otherwise stops
       working, the client sends an HTTP GET request to the
       "registration_client_uri" with the "registration_access_token" as
       its authorization.  This response will contain the client's
       refreshed "client_secret" along with any metadata values
       registered to that client, some of which may have changed.  Its
       "client_id" will remain the same.




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   j.  If the client needs to update its configuration on the
       authorization server, it sends an HTTP PUT request to the
       "registration_client_uri" with the "registration_access_token" as
       its authorization.  The response will contain the client's
       changed metadata values.  Its "client_id" will remain the same.
   k.  If the client is uninstalled or otherwise deprovisioned, it can
       send an HTTP DELETE request to the "registration_client_uri" with
       the "registration_access_token" as its authorization.  This will
       effectively deprovision the client from the Authorization Server.

B.4.  Developer Automation

   The dynamic registration protocol can also be used in place of a
   manual registration portal, for instance as part of an automated
   build and deployment process.  In this scenario, the authorization
   server may require an initial access token for requests to its
   registration endpoint, as described in Protected Registration
   (Appendix B.3).  However, here the developer manages the client's
   registration instead of the client itself.  Therefore, the initial
   registration token and registration access token all remain with the
   developer.  The developer packages the client identifier with the
   client as part of the client's build process.

   a.  A developer is creating a client to use an authorization server
       and knows that instances of the client will not dynamically
       register at runtime.
   b.  If required for registrations at the authorization server, the
       developer performs an OAuth 2.0 authorization of his build
       environment against the authorization server using any valid
       OAuth 2.0 flow.  The authorization server and is issues an
       initial access token to the developer's build environment in the
       form of an OAuth 2.0 Bearer Token [RFC6750].
   c.  The developer configures his build environment to send an HTTP
       POST request to the client registration endpoint at the
       authorization server with the client's metadata, using the
       initial access token obtained the previous step as an OAuth 2.0
       Bearer Token [RFC6750].
   d.  The authorization server issues a client identifier and returns
       it to the developer along with a registration access token and a
       reference to the client's client configuration endpoint.
   e.  The developer packages the client identifier with the client and
       stores the "registration_access_token", and
       "registration_client_uri" in the deployment system.
   f.  The client uses the its "client_id" and "client_secret" (if
       provided) to request OAuth 2.0 tokens using any supported OAuth
       2.0 flow.
   g.  If the client's "client_secret" expires or otherwise stops
       working, the developer's deployment system sends an HTTP GET



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       request to the "registration_client_uri" with the
       "registration_access_token" as its authorization.  This response
       will contain the client's refreshed "client_secret" along with
       any changed metadata values.  Its "client_id" will remain the
       same.  These new values will then be packaged and shipped to or
       retrieved by instances of the client, if necessary.
   h.  If the developer needs to update its configuration on the
       authorization server, the deployment system sends an HTTP PUT
       request to the "registration_client_uri" with the
       "registration_access_token" as its authorization.  This response
       will contain the client's changed metadata values.  Its
       "client_id" will remain the same.  These new values will then be
       packaged and shipped to or retrieved by instances of the client,
       if necessary.
   i.  If the client is deprovisioned, the developer's deployment system
       can send an HTTP DELETE request to the "registration_client_uri"
       with the "registration_access_token" as its authorization.  This
       will effectively deprovision the client from the authorization
       server and prevent any instances of the client from functioning.

Appendix C.  Document History

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

   - 00

   o  Partitioned dyn-reg specification into core and management specs

   [[ Previous changelog from draft-ietf-oauth-dyn-reg ]]

   -14

   o  Added software_id and software_version metadata fields
   o  Added direct references to RFC6750 errors in read/update/delete
      methods

   -13

   o  Fixed broken example text in registration request and in delete
      request
   o  Added security discussion of separating clients of different grant
      types
   o  Fixed error reference to point to RFC6750 instead of RFC6749
   o  Clarified that servers must respond to all requests to
      configuration endpoint, even if it's just an error code
   o  Lowercased all Terms to conform to style used in RFC6750

   -12



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   o  Improved definition of Initial Access Token
   o  Changed developer registration scenario to have the Initial Access
      Token gotten through a normal OAuth 2.0 flow
   o  Moved non-normative client lifecycle examples to appendix
   o  Marked differentiating between auth servers as out of scope
   o  Added protocol flow diagram
   o  Added credential rotation discussion
   o  Called out Client Registration Endpoint as an OAuth 2.0 Protected
      Resource
   o  Cleaned up several pieces of text

   -11

   o  Added localized text to registration request and response
      examples.
   o  Removed "client_secret_jwt" and "private_key_jwt".
   o  Clarified "tos_uri" and "policy_uri" definitions.
   o  Added the OAuth Token Endpoint Authentication Methods registry for
      registering "token_endpoint_auth_method" metadata values.
   o  Removed uses of non-ASCII characters, per RFC formatting rules.
   o  Changed "expires_at" to "client_secret_expires_at" and "issued_at"
      to "client_id_issued_at" for greater clarity.
   o  Added explanatory text for different credentials (Initial Access
      Token, Registration Access Token, Client Credentials) and what
      they're used for.
   o  Added Client Lifecycle discussion and examples.
   o  Defined Initial Access Token in Terminology section.

   -10

   o  Added language to point out that scope values are service-specific
   o  Clarified normative language around client metadata
   o  Added extensibility to token_endpoint_auth_method using absolute
      URIs
   o  Added security consideration about registering redirect URIs
   o  Changed erroneous 403 responses to 401's with notes about token
      handling
   o  Added example for initial registration credential

   -09

   o  Added method of internationalization for Client Metadata values
   o  Fixed SAML reference

   -08

   o  Collapsed jwk_uri, jwk_encryption_uri, x509_uri, and
      x509_encryption_uri into a single jwks_uri parameter



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   o  Renamed grant_type to grant_types since it's a plural value
   o  Formalized name of "OAuth 2.0" throughout document
   o  Added JWT Bearer Assertion and SAML 2 Bearer Assertion to example
      grant types
   o  Added response_types parameter and explanatory text on its use
      with and relationship to grant_types

   -07

   o  Changed registration_access_url to registration_client_uri
   o  Fixed missing text in 5.1
   o  Added Pragma: no-cache to examples
   o  Changed "no such client" error to 403
   o  Renamed Client Registration Access Endpoint to Client
      Configuration Endpoint
   o  Changed all the parameter names containing "_url" to instead use
      "_uri"
   o  Updated example text for forming Client Configuration Endpoint URL

   -06

   o  Removed secret_rotation as a client-initiated action, including
      removing client secret rotation endpoint and parameters.
   o  Changed _links structure to single value registration_access_url.
   o  Collapsed create/update/read responses into client info response.
   o  Changed return code of create action to 201.
   o  Added section to describe suggested generation and composition of
      Client Registration Access URL.
   o  Added clarifying text to PUT and POST requests to specify JSON in
      the body.
   o  Added Editor's Note to DELETE operation about its inclusion.
   o  Added Editor's Note to registration_access_url about alternate
      syntax proposals.

   -05

   o  changed redirect_uri and contact to lists instead of space
      delimited strings
   o  removed operation parameter
   o  added _links structure
   o  made client update management more RESTful
   o  split endpoint into three parts
   o  changed input to JSON from form-encoded
   o  added READ and DELETE operations
   o  removed Requirements section
   o  changed token_endpoint_auth_type back to
      token_endpoint_auth_method to match OIDC who changed to match us




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   -04

   o  removed default_acr, too undefined in the general OAuth2 case
   o  removed default_max_auth_age, since there's no mechanism for
      supplying a non-default max_auth_age in OAuth2
   o  clarified signing and encryption URLs
   o  changed token_endpoint_auth_method to token_endpoint_auth_type to
      match OIDC

   -03

   o  added scope and grant_type claims
   o  fixed various typos and changed wording for better clarity
   o  endpoint now returns the full set of client information
   o  operations on client_update allow for three actions on metadata:
      leave existing value, clear existing value, replace existing value
      with new value

   -02

   o  Reorganized contributors and references
   o  Moved OAuth references to RFC
   o  Reorganized model/protocol sections for clarity
   o  Changed terminology to "client register" instead of "client
      associate"
   o  Specified that client_id must match across all subsequent requests
   o  Fixed RFC2XML formatting, especially on lists

   -01

   o  Merged UMA and OpenID Connect registrations into a single document
   o  Changed to form-paramter inputs to endpoint
   o  Removed pull-based registration

   -00

   o  Imported original UMA draft specification

Authors' Addresses

   Justin Richer (editor)
   The MITRE Corporation

   Email: jricher@mitre.org







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   John Bradley
   Ping Identity

   Email: ve7jtb@ve7jtb.com


   Michael B. Jones
   Microsoft

   Email: mbj@microsoft.com
   URI:   http://self-issued.info/


   Maciej Machulak
   Newcastle University

   Email: m.p.machulak@ncl.ac.uk
   URI:   http://ncl.ac.uk/

































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