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Versions: (draft-richer-oauth-dyn-reg-core) 00 01 02 03 04 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 RFC 7591

Network Working Group                                     J. Richer, Ed.
Internet-Draft                                     The MITRE Corporation
Intended status: Standards Track                              J. Bradley
Expires: May 31, 2013                                      Ping Identity
                                                                M. Jones
                                                               Microsoft
                                                             M. Machulak
                                                    Newcastle University
                                                       November 27, 2012


               OAuth Dynamic Client Registration Protocol
                      draft-ietf-oauth-dyn-reg-02

Abstract

   This specification defines an endpoint and protocol for dynamic
   registration of OAuth Clients at an Authorizaiton 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 May 31, 2013.

Copyright Notice

   Copyright (c) 2012 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 . . . . . . . . . . . . . . . . . . . . . . . . .  3
     1.1.  Notational Conventions . . . . . . . . . . . . . . . . . .  3
     1.2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . .  3
     1.3.  Requirements . . . . . . . . . . . . . . . . . . . . . . .  4
       1.3.1.  The client needs to be uniquely identifiable by
               the authorization server . . . . . . . . . . . . . . .  4
       1.3.2.  The authorization server must collect metadata
               about a client for later user interaction  . . . . . .  4
       1.3.3.  The authorization server should have the option of
               strongly authenticating the client and its metadata  .  4
       1.3.4.  Dynamic client registration must be possible from
               both web-server applications and applications with
               other capabilities and limitations, such as native
               applications . . . . . . . . . . . . . . . . . . . . .  4
       1.3.5.  Transaction integrity must be ensured  . . . . . . . .  5
   2.  Client Metadata  . . . . . . . . . . . . . . . . . . . . . . .  5
   3.  Client Registration Endpoint . . . . . . . . . . . . . . . . .  7
     3.1.  Client Registration Request  . . . . . . . . . . . . . . .  9
     3.2.  Client Registration Response . . . . . . . . . . . . . . . 10
     3.3.  Client Update Request  . . . . . . . . . . . . . . . . . . 11
     3.4.  Client Update Response . . . . . . . . . . . . . . . . . . 12
     3.5.  Rotate Secret Request  . . . . . . . . . . . . . . . . . . 12
     3.6.  Rotate Secret Response . . . . . . . . . . . . . . . . . . 13
     3.7.  Client Registration Error Response . . . . . . . . . . . . 14
   4.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 15
   5.  Security Considerations  . . . . . . . . . . . . . . . . . . . 15
   6.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 16
   7.  Document History . . . . . . . . . . . . . . . . . . . . . . . 16
   8.  Normative References . . . . . . . . . . . . . . . . . . . . . 17
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 18















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1.  Introduction

   In some use-case scenarios, it is desirable or necessary to allow
   OAuth clients to obtain authorization from an OAuth authorization
   server without the two parties having previously interacted.
   Nevertheless, in order for the authorization server to accurately
   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 OAuth2 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 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 Secret.

   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 display name and icon to be presented to
   the user during the authorization step.  This draft provides a method
   for the client to register and update this information over time.

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 [RFC6750].

   This specification defines the following additional terms:

   o  Client Registration Endpoint: The OAuth 2.0 Endpoint through which
      a Client can request new registration and manage the metadata
      associated with it.

   o  Registration Access Token: An OAuth 2.0 Bearer Token issued by the
      Authorization Server through the Client Registration Endpoint



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      which is used by the Client to authenticate itself during update
      and secret rotation operations.

1.3.  Requirements

   [[ Following are proposed requirements for dynamic client
   registration.  This section is intended for discussion and will
   likely be removed in the final draft. ]]

1.3.1.  The client needs to be uniquely identifiable by the
        authorization server

   In order for an authorization server to do proper user-delegated
   authorization and prevent unauthorized access it must be able to
   identify clients uniquely.  As is done today in OAuth, the client
   identifier (and optional secret) should thus be issued by the
   authorization server and not simply accepted as proposed by the
   client.

1.3.2.  The authorization server must collect metadata about a client
        for later user interaction

   In order for the authorization server to describe a client to an end-
   user in an authorization step it needs information about the client.
   This can be the client name at a minimum, but today servers usually
   request at least a description, a homepage URL, and an icon when
   doing manual registration.

1.3.3.  The authorization server should have the option of strongly
        authenticating the client and its metadata

   In order to prevent spoofing of clients and enable dynamic building
   of strong trust relationships, the authorization server should have
   the option to verify the provided information.  This might be solved
   using message signature verification.

1.3.4.  Dynamic client registration must be possible from both web-
        server applications and applications with other capabilities and
        limitations, such as native applications

   Each instance of a native application (that is, the specific instance
   running on each device) that is installed and run by the same user
   may need the option of getting a unique client identifier.  In this
   case, there are implications around gathering and displaying enough
   information to ensure that the end-user is delegating authorization
   to the intended application.  The registration protocol should be
   simple and flexible enough to allow for multiple types of
   applications.



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1.3.5.  Transaction integrity must be ensured

   When a client sends information to a server endpoint, it might take
   time for this data to propagate through big server installations that
   spread across various data centers.  Care needs to be taken that
   subsequent interactions with the user after the registration process,
   such as an authorization request, show the correct data.


2.  Client Metadata

   Clients generally have an array of metadata associated with their
   unique Client Identifier at the Authorization Server.  These can
   range from human-facing display strings, such as a client name, to
   items that impact the security of the protocol, such as the list of
   valid redirect URIs.

   Extensions and profiles of this specification MAY expand this list,
   but MUST at least accept all parameters on this list.  The
   Authorization Server MUST ignore any additional parameters sent by
   the Client that it does not understand.

   redirect_uris
      REQUIRED A space-delimited list of redirect URIs.

   client_name
      RECOMMENDED.  Human-readable name of the Client to be presented to
      the user.

   client_url
      RECOMMENDED.  URL of the homepage of the client.  If present, the
      server SHOULD display this URL to the end user.

   logo_url
      OPTIONAL.  URL that references a logo for the Client application.
      If present, the server SHOULD display this image to the end user
      during approval.

   contacts
      OPTIONAL.  Space delimited list of email addresses for people
      responsible for this client.  The Authorization Server MAY may
      these addresses available to end users for support queries.  An
      Authorization Server MAY use these email addresses as identifiers
      for an administrative page for this client.







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   tos_url
      OPTIONAL.  URL that points to a human-readable Terms of Service
      for the Client.  The Authorization Server SHOULD display this URL
      to the End-User if it is given.

   token_endpoint_auth_method
      OPTIONAL.  The requested authentication type for the Token
      Endpoint.  Valid values are:

      *  "none" this 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 OAuth2.0 section 2.3.1

      *  "client_secret_basic" the client uses HTTP Basic defined in
         OAuth 2.0 section 2.3.1

      *  "client_secret_jwt" the client uses the JWT Assertion profile
         with a semetric secret issued by the server

      *  _private_key_jwt_ the client uses the JWT Assertion profile
         with its own private key

      Other Authentication methods may be defined by extension.  If
      unspecified or omitted, the default is "client_secret_basic" HTTP
      Basic Authentication Scheme as specified in Section 2.3.1 of OAuth
      2.0 [RFC6749].

   policy_url
      OPTIONAL.  A URL location that the Client provides to the End-User
      to read about the how the profile data will be used.  The
      Authorization Server SHOULD display this URL to the End-User if it
      is given.

   jwk_url
      OPTIONAL.  URL for the Client's JSON Web Key [JWK] document that
      is used for signing Token Endpoint Requests.  If
      jwk_encryption_url is not provided, the key at jwk_url is also
      used as the key to encrypt responses to the Client.  If the Client
      registers both "x509_url" and "jwk_url", the keys contained in
      both formats MUST be the same.

   jwk_encryption_url
      OPTIONAL.  URL for the Client's JSON Web Key [JWK] that is used to
      encrypt any responses to the Client.  If the Client registers both
      "jwk_encryption_url" and "x509_encryption_url", the keys contained
      in both formats MUST be the same.



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   x509_url
      OPTIONAL.  URL for the Client's PEM encoded X.509 Certificate or
      Certificate chain that is used for signing Token Endpoint
      Requests.  If "x509_encryption_url" is not provided, "x509_url" it
      is also used to encrypt responses to the Client.  If the Client
      registers both "x509_url" and "jwk_url", the keys contained in
      both formats MUST be the same.

   x509_encryption_url
      OPTIONAL.  URL for the Client's PEM encoded X.509 Certificate or
      Certificate chain that is used to encrypt the ID Token and User
      Info Endpoint Responses to the Client.  If the Client registers
      both "jwk_encryption_url" and "x509_encryption_url", the keys
      contained in both formats SHOULD be the same.

   default_max_age
      OPTIONAL.  Maximum age of a session in integer seconds.  Specifies
      that the End-User must be actively authenticated if any present
      authentication is older than the specified number of seconds by
      default.

   default_acr
      OPTIONAL.  Default Authentication Context class Reference.  String
      that specifies the default authentication context value that the
      Authorization server must use for processing requests from this
      client.


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 register itself
   with the Authorization Server.  The Client Registration Endpoint MUST
   accept HTTP POST messages with request parameters encoded in the
   entity body using the "application/x-www-form-urlencoded" format.
   The Client Registration Endpoint MUST be protected by 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].

   The Endpoint defines three operations that a client can take on it,
   switched by the "operation" parameter:






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   o  client_register: request that the Authorization Server generate a
      new Client Identifier (and optionally a Client Secret) and
      associate it with the set of presented metadata (Section 2)

   o  client_update: update the metadata (Section 2) associated with a
      Client Identifier

   o  rotate_secret: issue a new Registration Access Token and, if
      applicable, a Client Secret for a Client

   In order to facilitate registered clients updating their information,
   the Client Registration Endpoint issues a request_access_token for
   clients to securely identify themselves in future connections.  As
   such, the Endpoint MUST accept requests with OAuth 2.0 Bearer Tokens
   [RFC6750] for these operations.

   In order to support open registration and facilitate wider
   interoperability, the Client Registration Endpoint SHOULD allow
   client_register requests with no further authentication.  These
   requests MAY be rate-limited to prevent a denial-of-service attack on
   the Client Registration Endpoint.

   In addition, the Client Registration Endpoint MAY accept an initial
   authorization credential in the form of an OAuth 2.0 [RFC6749] access
   token in order to limit registration to only previously authorized
   parties.  The method by which this access token is obtained by the
   registrant is generally out-of-band and is out of scope of this
   specification.

   These two aspects, operation selection and client authentication, are
   represented by two parameters common to all operations:

   operation  REQUIRED.  Values are "client_register" (for new
      registrations), "rotate_secret" to request rotation of the
      "client_secret", and "client_update" (for updating parameters of
      an existing "client_id").

   access_token  OPTIONAL.  An OAuth2 Bearer token used to access the
      Client Registration Endpoint, as defined in OAuth2 Bearer.  This
      parameter MUST NOT be sent if the Access Token is sent in the HTTP
      Authorization header as described in Section 7.1 of OAuth 2.0
      [RFC6749].  Access Tokens sent in the authorization header must be
      OAuth 2.0 Bearer Tokens [RFC6750].

   Each operation takes a different parameter set, and all operations
   are described below.

   The Client Registration Endpoint MUST ignore all parameters it does



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   not understand.

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 the two parameters described above as well as any
   parameters described in Client Metadata (Section 2).

   operation
      REQUIRED.  MUST have the value "client_register"
   access_token
      OPTIONAL. used to restrict new client registration.  This
      parameter MUST NOT be sent if the Access Token is sent in the HTTP
      Authorization header as described in Section 7.1 of OAuth 2.0
      [RFC6749].  Access Tokens sent in the authorization header must be
      OAuth 2.0 Bearer Tokens [RFC6750].
   redirect_uris  REQUIRED
   client_name  RECOMMENDED
   client_url  RECOMMENDED
   logo_url  OPTIONAL
   contacts  OPTIONAL
   tos_url  OPTIONAL
   token_endpoint_auth_method  OPTIONAL
   policy_url  OPTIONAL
   jwk_url  OPTIONAL
   jwk_encryption_url  OPTIONAL
   x509_url  OPTIONAL
   x509_encryption_url  OPTIONAL
   default_max_age  OPTIONAL
   default_acr  OPTIONAL
   For example, a client could send the following registration request
   to the Client Registration Endpoint:
















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   Following is a non-normative example request (with line wraps for
   display purposes only):
   POST /register HTTP/1.1
   Accept: application/x-www-form-urlencoded
   Host: server.example.com

   operation=client_register
   &redirect_uris=https://client.example.org/callback
       %20https://client.example.org/callback2
   &client_name=My%20Example%20Client
   &logo_url=https://client.example.org/logo.png
   &token_endpoint_auth_type=client_secret_basic
   &jwk_url=https://client.example.org/my_rsa_public_key.jwk

3.2.  Client Registration Response

   Upon successful registration, the Client Registration Endpoint
   returns the newly-created Client Identifier and, optionally, a Client
   Secret.  The response also contains a Registration Access Token that
   is to be used by the client to perform subsequent operations at this
   endpoint, such as client_update and rotate_secret.  These items are
   returned as a JSON document with the following fields as top-level
   members of the root JSON object.

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

   client_secret
      OPTIONAL.  The Client secret.  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
      Section 2.3.1.

   registration_access_token
      REQUIRED.  The Access token to be used by the client to perform
      "client_update" and "rotate_secret" requests.

   issued_at
      OPTIONAL.  Specifies the timestamp when the Client Identifier was
      issued.  The timestamp value MUST be a positive integer.  The
      value is expressed in the number of seconds since January 1, 1970
      00:00:00 GMT.

   expires_at
      OPTIONAL.  The number of seconds from 1970-01-01T0:0:0Z as
      measured in UTC that the "client_secret" will expire or "0" if
      they do not expire.  See RFC 3339 [RFC3339] for details regarding



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      date/times in general and UTC in particular.

   Following is a non-normative example response:
   HTTP/1.1 200 OK
   Content-Type: application/json
   Cache-Control: no-store

   {
    "client_id":"s6BhdRkqt3",
    "client_secret":
     "cf136dc3c1fd9153029bb9c6cc9ecead918bad9887fce6c93f31185e5885805d",
     "registration_access_token": "reg-23410913-abewfq.123483",
    "expires_at":2893276800
   }

3.3.  Client Update Request

   This operation updates a previously-registered client with new
   metadata at the Authorization Server.  This request MUST be protected
   by the Registration Authorization Token associated with the Client.
   This request MAY include any fields described in Client Metadata
   (Section 2).  The values of Client Metadata fields in this request
   MUST replace (not augment) the values previously associated with this
   Client.  Empty values in Client Metadata MUST be taken as a request
   to clear any existing value of that field.

   operation
      REQUIRED, MUST have the value "client_update"
   access_token
      REQUIRED, unless presented in the Authorization Header as in
      OAuth2 Bearer [RFC6750].  The Registration Access Token that was
      issued during the client_register step, or previous client_update
      or rotate_secret calls.
   redirect_uris  REQUIRED
   client_name  RECOMMENDED
   client_url  RECOMMENDED
   logo_url  OPTIONAL
   contacts  OPTIONAL
   tos_url  OPTIONAL
   token_endpoint_auth_method  OPTIONAL
   policy_url  OPTIONAL
   jwk_url  OPTIONAL
   jwk_encryption_url  OPTIONAL
   x509_url  OPTIONAL







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   x509_encryption_url  OPTIONAL
   default_max_age  OPTIONAL
   default_acr  OPTIONAL
   For example, a 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
   Accept: application/x-www-form-urlencoded
   Host: server.example.com
   Authorization: Bearer reg-23410913-abewfq.123483

   operation=client_update
   &redirect_uris=https://client.example.org/callback
       %20https://client.example.org/callback2
   &client_name=My%20Example%20
   &logo_url=https://client.example.org/logo.png
   &token_endpoint_auth_type=client_secret_basic
   &jwk_url=https://client.example.org/my_rsa_public_key.jwk

3.4.  Client Update Response

   Upon successful update, the Client Registration Endpoint returns a
   JSON document with the following fields as top-level members of the
   root JSON object.

   client_id
      REQUIRED.  The unique Client identifier, MUST equal the value of
      the client_id returned in the original client_register request.

   Following is a non-normative example response:
   HTTP/1.1 200 OK
   Content-Type: application/json
   Cache-Control: no-store

   {
    "client_id":"s6BhdRkqt3",
   }

   [[ Editor's note: should this return the entire client data object,
   for confirmation and review, including any fields that may have been
   asserted by the AS? ]]

3.5.  Rotate Secret Request

   This operation allows the client to rotate its current Registration
   Access Token as well as its Client Secret, if it has one.



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   operation  REQUIRED.  MUST have the value rotate_secret

   access_token  REQUIRED.  The Registration Access Token that was
      issued during the client_register step, or previous client_update
      or rotate_secret calls.  This parameter MUST NOT be sent if the
      Access Token is sent in the HTTP Authorization header as described
      in Section 7.1 of OAuth 2.0 [RFC6749].  Access Tokens sent in the
      authorization header must be OAuth 2.0 Bearer Tokens [RFC6750].

   Following is a non-normative example request (with line wraps for
   display purposes only):
   POST /register HTTP/1.1
   Accept: application/x-www-form-urlencoded
   Host: server.example.com
   Authorization: Bearer reg-23410913-abewfq.123483

   operation=rotate_secret

3.6.  Rotate Secret Response

   Upon successful rotation of the Registration Access Token and
   optionally the Client Secret, the Client Registration Endpoint
   returns a JSON document with the following fields as top-level
   members of the root JSON object.

   client_id
      REQUIRED.  The unique Client identifier, MUST match the client_id
      issued in the original client_register request.

   client_secret
      REQUIRED if the server initially issued this Client a Client
      Secret, otherwise the server MUST NOT return a value.  The value
      MUST be unique for each "client_id".

   registration_access_token
      REQUIRED The Access token to be used by the client to perform
      subsequent "client_update" and "rotate_secret" requests.

   issued_at
      OPTIONAL.  Specifies the timestamp when the identifier was issued.
      The timestamp value MUST be a positive integer.  The value is
      expressed in the number of seconds since January 1, 1970 00:00:00
      GMT.

   expires_at
      OPTIONAL.  The number of seconds from 1970-01-01T0:0:0Z as
      measured in UTC that the "client_secret" will expire or "0" if
      they do not expire.  See RFC 3339 [RFC3339] for details regarding



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      date/times in general and UTC in particular.

   Following is a non-normative example response:
   HTTP/1.1 200 OK
   Content-Type: application/json
   Cache-Control: no-store

   {
    "client_id":"s6BhdRkqt3",
    "client_secret":
     "cf136dc3c1fd9153029bb9c6cc9ecead918bad9887fce6c93f31185e5885805d",
     "registration_access_token": "this.is.a.access.token.value.ffx83",
    "expires_at":2893276800
   }

   The Authorization Server SHOULD discard and invalidate the Request
   Access Token and the Client Secret associated with this Client after
   successful completion of this request.

3.7.  Client Registration Error Response

   When an OAuth error condition occurs, the Client Registration
   Endpoint returns an Error Response as defined in Section 5.2 of the
   OAuth 2.0 specification.

   When a registration error condition occurs, the Client Registration
   Endpoint returns a HTTP 400 status code including a JSON object
   describing the error in the response body.

   The JSON object contains two members:

   error
      The error code, a single ASCII string.

   error_description
      The additional text description of the error for debugging.

   This specification defines the following error codes:

   invalid_operation
      The value of "operation" is invalid or not supported.

   invalid_redirect_uri
      The value of one or more "redirect_uris" is invalid.







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   invalid_client_metadata
      The value of one of the client metadata (Section 2) fields is
      invalid.

   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

   {
    "error":"invalid_operation",
    "error_description":"The value of the operation parameter must
     be one of client_register, rotate_secret or client_update."
   }


4.  IANA Considerations

   This document makes no requests of IANA.


5.  Security Considerations

   [[ Editor's note: Following are some security considerations taken
   whole from the UMA and OpenID Connect source drafts. ]]

   Since requests to the Client Registration Endpoint result in the
   transmission of clear-text credentials (in the HTTP request and
   response), the 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].

   As this endpoint is an OAuth2 Protected Resource, requests to the
   Registration Endpoint SHOULD have some rate limiting on failures to
   prevent the Registration Access Token from being disclosed though
   repeated access attempts.

   The authorization server MUST treat all client metadata as self-
   asserted.  A rogue Client might use the name and logo for the
   legitimate Client, which it is trying to impersonate.  An
   Authorization Server needs to take steps to mitigate this phishing
   risk, since the logo could confuse users into thinking they're
   logging in to the legitimate Client.  For instance, an Authorization



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   Server could warn if the domain/site of the logo doesn't match the
   domain/site of redirect URIs.  An Authorization Server can also make
   warnings against untrusted Clients in all cases, especially if
   they're dynamically registered, have not been trusted by any users at
   the Authorization Server before.

   In a situation where the Authorization Server is supporting open
   Client registration, it must be extremely careful with any URL
   provided by the Client that will be displayed to the user (e.g.
   "logo_url" and "policy_url").  A rogue Client could specify a
   registration request with a reference to a drive-by download in the
   "policy_url".  The Authorization Server should check to see if the
   "logo_url" and "policy_url" have the same host as the hosts defined
   in the array of "redirect_uris".

   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 Client could be left in a situation
   where it has no means of updating itself and must register itself
   anew.  As the Registration Access Tokens are long-term credentials,
   they MUST be protected by the Client as a secret. [[ Editor's note:
   with the right error codes returned from client_update, the AS could
   force the Client to call rotate_secret before going forward,
   lessening the window for abuse of a leaked registration token. ]]


6.  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: Torsten Lodderstedt, Eve Maler,
   Thomas Hardjono, Christian Scholz, Nat Sakimura, George Fletcher,
   Amanda Anganes, and Domenico Catalano.


7.  Document History

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

   - 02

   o  Reorganized contributors and references

   o  Moved OAuth references to RFC





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   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


8.  Normative References

   [JWA]      Jones, M., "JSON Web Algorithms", May 2012.

   [JWE]      Jones, M., Rescorla, E., and J. Hildebrand, "JSON Web
              Encryption (JWE)", May 2012.

   [JWK]      Jones, M., "JSON Web Key (JWK)", May 2012.

   [JWS]      Jones, M., Bradley, J., and N. Sakimura, "JSON Web
              Signature", May 2012.

   [JWT]      Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token",
              May 2012.

   [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.

   [RFC2617]  Franks, J., Hallam-Baker, P., Hostetler, J., Lawrence, S.,
              Leach, P., Luotonen, A., and L. Stewart, "HTTP
              Authentication: Basic and Digest Access Authentication",
              RFC 2617, June 1999.




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   [RFC3339]  Klyne, G., Ed. and C. Newman, "Date and Time on the
              Internet: Timestamps", RFC 3339, July 2002.

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

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

   [RFC5785]  Nottingham, M. and E. Hammer-Lahav, "Defining Well-Known
              Uniform Resource Identifiers (URIs)", RFC 5785,
              April 2010.

   [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.


Authors' Addresses

   Justin Richer (editor)
   The MITRE Corporation


   Phone:
   Fax:
   Email: jricher@mitre.org
   URI:


   John Bradley
   Ping Identity

   Email: ve7jtb@ve7jtb.com









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   Michael B. Jones
   Microsoft

   Email: mbj@microsoft.com


   Maciej Machulak
   Newcastle University

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








































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