Network Working Group                                     J. Richer, Ed.
Internet-Draft                                     The MITRE Corporation
Intended status: Standards Track                             T. Hardjono                              J. Bradley
Expires: May 9, 31, 2013                                                 MIT
                                                             M. Machulak
                                                    Newcastle University
                                                                E. Maler
                                                             XMLgrrl.com
                                                               C. Scholz
                                                         COM.lounge GmbH
                                                             N. Sakimura
                                                                     NRI
                                                              J. Bradley                                      Ping Identity
                                                                M. Jones
                                                               Microsoft
                                                             M. Machulak
                                                    Newcastle University
                                                       November 5, 27, 2012

               OAuth Dynamic Client Registration Protocol
                      draft-ietf-oauth-dyn-reg-01
                      draft-ietf-oauth-dyn-reg-02

Abstract

   This specification proposes defines an endpoint and protocol for dynamic
   registration of OAuth Dynamic Client Registration
   protocol. 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 9, 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
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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 Registration Endpoint Metadata  . . . . . . . . . . . . . . . . . . . . . . .  5
     2.1.
   3.  Client Association Request Registration Endpoint . . . . . . . . . . . . . . . . .  6
     2.2.  7
     3.1.  Client Association Response Registration Request  . . . . . . . . . . . . . . .  8
     2.3.  9
     3.2.  Client Update Request  . . . Registration Response . . . . . . . . . . . . . . .  9
     2.4. 10
     3.3.  Client Update Response Request  . . . . . . . . . . . . . . . . . . 10
     2.5.  Rotate Secret Request 11
     3.4.  Client Update Response . . . . . . . . . . . . . . . . . . 11
     2.6. 12
     3.5.  Rotate Secret Response Request  . . . . . . . . . . . . . . . . . . 11
     2.7.  Client Registration Error 12
     3.6.  Rotate Secret Response . . . . . . . . . . . . 12
   3.  Client Metadata  . . . . . . . . . . . 13
     3.7.  Client Registration Error Response . . . . . . . . . . . . 13 14
   4.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 15
   5.  Security Considerations  . . . . . . . . . . . . . . . . . . . 15
   6.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 16
   7.  Document History . . . . . . . . . . . . . . . . . . . . . . . 16
   8.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 17
     8.1.  Normative References . . . . . . . . . . . . . . . . . . . 17
     8.2.  Non-Normative References . . . . . . . . . . . . . . . . . 18 17
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 19 18

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 meta information, 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 [OAuth2.0]. [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
      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.

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 Registration Endpoint

   The Client Registration Endpoint is Metadata

   Clients generally have an OAuth 2.0 Endpoint defined in
   this document that is designed to allow a Client to register itself array of metadata associated with their
   unique Client Identifier at the Authorization Server.  The Client Registration Endpoint  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 HTTP POST messages with request all parameters encoded in the
   entity body using the "application/x-www-form-urlencoded" format. on this list.  The Client Registration Endpoint
   Authorization Server 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 ignore any additional transport-layer
   mechanisms meeting its security requirements.  When using TLS, parameters sent by
   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 it does not understand.

   redirect_uris
      REQUIRED A space-delimited list of redirect URIs.

   client_name
      RECOMMENDED.  Human-readable name of the "operation" parameter:

   o  client_associate: generate a new Client Identifier (and optionally
      a Client Secret) and associate it with to be presented to
      the set user.

   client_url
      RECOMMENDED.  URL of presented
      metadata (Section 3)

   o  client_update: update the metadata (Section 3) associated with a
      Client Identifier

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

   tos_url
      OPTIONAL.  URL that points to a Client

   In order human-readable Terms of Service
      for the Client.  The Authorization Server SHOULD display this URL
      to facilitate registered clients updating their information, the Client Registration Endpoint issues 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 request_access_token for
   clients to securely identify themselves client secret

      *  "client_secret_post" the client uses the HTTP POST parameters
         defined in future connections.  As
   such, OAuth2.0 section 2.3.1

      *  "client_secret_basic" the Endpoint MUST accept requests with client uses HTTP Basic defined in
         OAuth 2.0 Bearer Tokens
   [OAuth.Bearer] for these operations.

   In order to support open registration and facilitate wider
   interoperability, section 2.3.1

      *  "client_secret_jwt" the Client Registration Endpoint SHOULD allow
   client_associate requests client uses the JWT Assertion profile
         with no further authentication.  These
   requests MAY be rate-limited to prevent a denial-of-service attack on semetric secret issued by the Client Registration Endpoint.

   In addition, server

      *  _private_key_jwt_ the Client Registration Endpoint MAY accept an initial
   authorization credential in client uses the form 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 an OAuth
      2.0 [OAuth2.0]
   access token in order [RFC6749].

   policy_url
      OPTIONAL.  A URL location that the Client provides to limit registration the End-User
      to only previously
   authorized parties. read about the how the profile data will be used.  The method by which
      Authorization Server SHOULD display this access token URL to the End-User if it
      is
   obtained by given.

   jwk_url
      OPTIONAL.  URL for the registrant Client's JSON Web Key [JWK] document that
      is generally out-of-band and used for signing Token Endpoint Requests.  If
      jwk_encryption_url is out of
   scope of this specification.

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

   operation  REQUIRED.  Values are "client_associate" (for new
      registrations), "rotate_secret"
      encrypt any responses to request rotation of the
      "client_secret", Client.  If the Client registers both
      "jwk_encryption_url" and "client_update" (for updating parameters of
      an existing "client_id").

   access_token "x509_encryption_url", the keys contained
      in both formats MUST be the same.

   x509_url
      OPTIONAL.  An OAuth2 Bearer token  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 access encrypt responses to the Client.  If the Client Registration Endpoint, as defined
      registers both "x509_url" and "jwk_url", the keys contained in OAuth2 Bearer.  This
      parameter
      both formats MUST NOT be sent if the Access Token same.

   x509_encryption_url
      OPTIONAL.  URL for the Client's PEM encoded X.509 Certificate or
      Certificate chain that is sent in used to encrypt the HTTP
      Authorization header as described 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 Section 7.1 both formats SHOULD be the same.

   default_max_age
      OPTIONAL.  Maximum age of OAuth 2.0
      [OAuth2.0].  Access Tokens sent a session in integer seconds.  Specifies
      that the authorization header End-User must be OAuth 2.0 Bearer Tokens [OAuth.Bearer].

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

   The 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 MUST ignore all parameters it does
   not understand.

2.1. Endpoint

   The Client Association Request

   This operation registers Registration Endpoint is an OAuth 2.0 Endpoint defined in
   this document that is designed to allow a new client Client to register itself
   with the Authorization Server.  The Authorization Server assigns this client a unique Client
   Identifier, optionally assigns a Client Secret, and associates the
   metadata given Registration Endpoint MUST
   accept HTTP POST messages with request parameters encoded in the request with
   entity body using the issued "application/x-www-form-urlencoded" format.
   The Client Identifier. Registration Endpoint MUST be protected by a transport-
   layer security mechanism when sending requests to the Registration
   Endpoint.  The
   request includes 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 two parameters described above as well as any
   parameters described in
   Client Metadata (Section 3).

   operation  REQUIRED, MUST have the value "client_associate"

   access_token  OPTIONAL, used to restrict new client registration
   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

   require_signed_request_object  OPTIONAL

   default_max_age  OPTIONAL

   default_acr  OPTIONAL

   For example, perform a TLS/SSL server certificate check, per RFC 6125
   [RFC6125].

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

   o  client_register: request
   to that the Authorization Server generate a
      new Client Registration Endpoint:

   Following is Identifier (and optionally 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 eyJhbGciOiJSUzI1NiJ9.eyJ ... fQ.8Gj_-sj ... _X

   operation=client_associate
   &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

2.2. Client Association Response

   Upon successful association, Secret) and
      associate it with the Client Registration Endpoint returns set of presented metadata (Section 2)

   o  client_update: update the newly-created Client Identifier and, optionally, metadata (Section 2) associated with a
      Client Secret.
   The response also contains Identifier

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

   In order to be
   used by facilitate registered clients updating their information,
   the client to perform subsequent operations at this endpoint.
   These items are returned as Client Registration Endpoint issues a JSON document with the following fields
   as top-level members of request_access_token for
   clients to securely identify themselves in future connections.  As
   such, the root JSON object.

   client_id  REQUIRED.  The unique Client identifier, Endpoint MUST NOT be
      currently valid accept requests with OAuth 2.0 Bearer Tokens
   [RFC6750] for any other registered Client.

   client_secret  OPTIONAL.  The these operations.

   In order to support open registration and facilitate wider
   interoperability, the Client secret.  This MUST Registration Endpoint SHOULD allow
   client_register requests with no further authentication.  These
   requests MAY be unique for
      each "client_id".  This value us used by confidential clients.  It
      is not required for clients selecting rate-limited to prevent a token_endpoint_auth_type 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 "private_key_jwt"

   registration_access_token  REQUIRED The Access an OAuth 2.0 [RFC6749] access
   token in order to be used 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 perform "client_update" and all operations:

   operation  REQUIRED.  Values are "client_register" (for new
      registrations), "rotate_secret"
      requests.

   issued_at to request rotation of the
      "client_secret", and "client_update" (for updating parameters of
      an existing "client_id").

   access_token  OPTIONAL.  Specifies the timestamp when  An OAuth2 Bearer token used to access the identifier was issued.
      The timestamp value
      Client Registration Endpoint, as defined in OAuth2 Bearer.  This
      parameter MUST NOT be a positive integer.  The value sent if the Access Token is
      expressed sent 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 HTTP
      Authorization header as measured in UTC that the "client_secret" will expire or "0" if
      they do not expire.  See RFC 3339 [RFC3339] for details regarding
      date/times described in general and UTC Section 7.1 of OAuth 2.0
      [RFC6749].  Access Tokens sent in particular.

   Following is the authorization header must be
      OAuth 2.0 Bearer Tokens [RFC6750].

   Each operation takes 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
   }

2.3. different parameter set, and all operations
   are described below.

   The Client Update Registration Endpoint MUST ignore all parameters it does
   not understand.

3.1.  Client Registration Request

   This operation updates registers a previously-registered client with new
   metadata at client to the Authorization Server.  This request MUST be protected
   by the Registration
   The Authorization Token associated 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.  This  The
   request MAY include includes the two parameters described above as well as any fields
   parameters described in Client Metadata (Section 3).  The values of Client Metadata fields in this
   request 2).

   operation
      REQUIRED.  MUST replace (not augment) have the values previously associated
   with this client_identifier.  Empty values in Client Metadata SHOULD
   be taken as a request to clear any existing value of that field.

   operation  REQUIRED, "client_register"
   access_token
      OPTIONAL. used to restrict new client registration.  This
      parameter MUST have NOT be sent if the value "client_update"

   access_token  REQUIRED, unless presented Access Token is sent in the HTTP
      Authorization Header header as described in OAuth2 Bearer [OAuth.Bearer].  The Registration Section 7.1 of OAuth 2.0
      [RFC6749].  Access Token
      that was issued during Tokens sent in the client_associate step, or previous
      client_update or rotate_secret calls. 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

   require_signed_request_object  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 eyJhbGciOiJSUzI1NiJ9.eyJ ... fQ.8Gj_-sj ... _X

   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

2.4.  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 NOT be
      currently valid for any other registered Client.

   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? ]]

2.5.  Rotate Secret Request

   This operation allows the client to rotate its current Client Secret,
   if it has one.  If the client has not been issued a Client Secret,
   this operation is an error. [[ Editor's note: could this request be
   used to rotate the Registration Access Token, even when there's not a
   client_secret?  Should something else be used to rotate the token
   independently?  This is an open issue. ]]

   operation  REQUIRED.  MUST have the value rotate_secret

   access_token  REQUIRED.  The Registration Access Token that was
      issued during the client_associate step, or previous client_update
      or rotate_secret calls. 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 eyJhbGciOiJSUzI1NiJ9.eyJ ... fQ.8Gj_-sj ... _X

   operation=rotate_secret

2.6.  Rotate Secret

   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 rotation of the client secret, 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  REQUIRED.
      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
      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 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
      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
   }

2.7.  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.

   invalid_client_metadata  The value of one of the client metadata
      (Section 3) fields is invalid. in UTC that the "client_secret" will expire or "0" if
      they do not expire.  See RFC 3339 [RFC3339] for details regarding
      date/times in general and UTC in particular.

   Following is a non-normative example of an error response:
   HTTP/1.1 400 Bad Request 200 OK
   Content-Type: application/json
   Cache-Control: no-store

   {
 "error":"invalid_operation",
 "error_description":"The value of the operation parameter must be one of client_associate, rotate_secret or client_update."
    "client_id":"s6BhdRkqt3",
    "client_secret":
     "cf136dc3c1fd9153029bb9c6cc9ecead918bad9887fce6c93f31185e5885805d",
     "registration_access_token": "reg-23410913-abewfq.123483",
    "expires_at":2893276800
   }

3.

3.3.  Client Metadata

   Clients generally have an array of metadata associated Update Request

   This operation updates a previously-registered client with their
   unique Client Identifier new
   metadata at the Authorization Server.  These can
   range from human-facing display strings, such as a client name, to
   items that impact  This request MUST be protected
   by the security of Registration Authorization Token associated with the protocol,

   Extensions and profiles of this specification Client.
   This request MAY expand include any fields described in Client Metadata
   (Section 2).  The values of Client Metadata fields in this list,
   but request
   MUST at least accept all parameters on replace (not augment) the values previously associated with this list.  The
   Authorization Server
   Client.  Empty values in Client Metadata MUST ignore be taken as a request
   to clear any additional parameters sent by existing value of that field.

   operation
      REQUIRED, MUST have the Client value "client_update"
   access_token
      REQUIRED, unless presented in the Authorization Header as in
      OAuth2 Bearer [RFC6750].  The Registration Access Token that it does not understand. was
      issued during the client_register step, or previous client_update
      or rotate_secret calls.
   redirect_uris  REQUIRED A space-delimited list of redirect URIs.
   client_name  RECOMMENDED.  Human-readable name of  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 Client to be
      presented following registration request
   to the user.

   client_url
      RECOMMENDED.  This field contains the URL of the homepage of the
      client.

   logo_url  OPTIONAL.  A URL that references Client Registration Endpoint:

   Following is a logo 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
      application.  If present, Registration Endpoint returns a
   JSON document with the server SHOULD display this image to following fields as top-level members of the end user during approval.

   contacts  OPTIONAL.  Space delimited list
   root JSON object.

   client_id
      REQUIRED.  The unique Client identifier, MUST equal the value of email addresses for
      people allowed to administer
      the information for this Client.
      This client_id returned in the original client_register request.

   Following is used by some providers to enable a web UI to modify 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
      Client information.

   tos_url  OPTIONAL.  URL that points to a human-readable Terms of
      Service entire client data object,
   for confirmation and review, including any fields that may have been
   asserted by the Client.  The Authorization Server SHOULD display
      this URL to AS? ]]

3.5.  Rotate Secret Request

   This operation allows the End-User client to rotate its current Registration
   Access Token as well as its Client Secret, if it is given.

   token_endpoint_auth_method  OPTIONAL.  The requested authentication
      type for has one.

   operation  REQUIRED.  MUST have the Token Endpoint. value rotate_secret

   access_token  REQUIRED.  The options are
      "client_secret_post", "client_secret_basic", "client_secret_jwt",
      and "private_key_jwt".  Other Authentication methods may be
      defined by extension.  If unspecified Registration Access Token that was
      issued during the client_register step, or omitted, previous client_update
      or rotate_secret calls.  This parameter MUST NOT be sent if the default
      Access Token is
      "client_secret_basic" sent in the HTTP Basic Authentication Scheme Authorization header as
      specified described
      in Section 2.3.1 7.1 of OAuth 2.0 [OAuth2.0]. [[ this list
      of terms needs to be expanded and fully defined, especially [RFC6749].  Access Tokens sent in
      reference to signed-jwt client authentication ]]

   policy_url  OPTIONAL.  A URL location that the Client provides to the
      End-User to read about the how the profile data will
      authorization header must be used.  The
      Authorization Server SHOULD display this URL to the End-User if it OAuth 2.0 Bearer Tokens [RFC6750].

   Following is given.

   jwk_url  OPTIONAL.  URL 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 Client's JSON Web Key [JWK] document
      that is used for signing Registration Access 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
   optionally the Client registers both "jwk_encryption_url" and
      "x509_encryption_url", Secret, the keys contained in both formats MUST be Client Registration Endpoint
   returns a JSON document with the same.

   x509_url  OPTIONAL.  URL for following fields as top-level
   members of 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 root JSON object.

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

   client_secret
      REQUIRED if the server initially issued this Client registers both "x509_url" and "jwk_url", a Client
      Secret, otherwise the keys
      contained in both formats server MUST NOT return a value.  The value
      MUST be the same.

   x509_encryption_url  OPTIONAL.  URL unique for the Client's PEM encoded
      X.509 Certificate or Certificate chain that is used each "client_id".

   registration_access_token
      REQUIRED The Access token to encrypt be used by the
      ID Token and User Info Endpoint Responses client to the Client.  If the
      Client registers both "jwk_encryption_url" perform
      subsequent "client_update" and
      "x509_encryption_url", "rotate_secret" requests.

   issued_at
      OPTIONAL.  Specifies the keys contained in both formats SHOULD
      be timestamp when the same.

   require_signed_request_object  OPTIONAL. identifier was issued.
      The JWS [JWS] "alg"
      algorithm [JWA] that timestamp value MUST be required by the Authorization Server. a positive integer.  The valid values are listed value is
      expressed in Section 3.1 the number of JWA [JWA].  Servers
      SHOULD support "RS256".

   default_max_age seconds since January 1, 1970 00:00:00
      GMT.

   expires_at
      OPTIONAL. (default max authentication age): Type:
      Integer - Specifies  The number of seconds from 1970-01-01T0:0:0Z as
      measured in UTC that the End-User must be actively
      authenticated "client_secret" will expire or "0" if any present authentication
      they do not expire.  See RFC 3339 [RFC3339] for details regarding
      date/times in general and UTC in particular.

   Following is older than 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
      specified number 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 seconds.  (The "max_age" request parameter
      corresponds to the OpenID
   OAuth 2.0 PAPE "max_auth_age" request
      parameter.)  The "max_age" claim in specification.

   When a registration error condition occurs, the request Client Registration
   Endpoint returns a HTTP 400 status code including a JSON object overrides
      this default value.

   default_acr  OPTIONAL. (default authentication context class
      reference): Type: String - Specifies
   describing the default value that error in the
      Authorization server must use for processing requests from this
      client. response body.

   The "acrs_supported" element of discovery JSON object contains two members:

   error
      The error code, a list single ASCII string.

   error_description
      The additional text description of the supported "acr" values error for this server. debugging.

   This specification defines the following error codes:

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

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

   invalid_client_metadata
      The value of one of the request object overrides this default value. 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. ]]

   o  No client authentication: The server should treat unsigned pushed
      client metadata as self-asserted.

   o  Weak client authentication: The server should treat unsigned
      pulled client metadata as self-asserted unless the domain of the
      client matches the client metadata URL and the URL is well-known
      and trusted.

   o  Strong client authentication: The server should treat signed
      client metadata (pushed or pulled) and a signed metadata URL as
      self-asserted unless it can verify the signature as being from a
      trusted source.

   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].

   Requests

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

   The authorization server MUST treat all client metadata as self-
   asserted.  A rogue RP Client might use the name and logo for the
   legitimate RP, Client, which it is trying to impersonate.  An IdP
   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 RP.  An IdP Client.  For instance, an Authorization
   Server could also warn if the domain/site of the logo doesn't match the
   domain/site of redirect URIs.  An IdP Authorization Server can also make
   warnings against untrusted RPs Clients in all cases, especially if
   they're dynamically registered, have not been trusted by any users at
   the IdP before, and want to use the logo
   feature. 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 Work Group
   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
   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.  References

8.1.  Normative References

   [JSON]     Crockford, D., "The application/json Media Type for
              JavaScript Object Notation (JSON)", 2006,
              <http://tools.ietf.org/html/rfc4627>.

   [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.

   [OAuth-Sig]
              Balfanz, D., "OAuth Signature proposals", 2010, <http://
              www.ietf.org/mail-archive/web/oauth/current/
              msg03893.html>.

   [OAuth.Bearer]
              Jones, M. and D. Hardt, "OAuth 2.0 Protocol: Bearer
              Tokens", Aug 2012.

   [OAuth2.0]
              Hardt, D., "OAuth 2.0 Authorization Protocol", July 2012.

   [OpenID.Messages]
              Sakimura, N., Bradley, J., Jones, M., de Medeiros, B.,
              Mortimore, C., and E. Jay, "OpenID Connect Messages 1.0",
              May 2012.

   [OpenID.Session]
              Sakimura, N., Bradley, J., Jones, M., de Medeiros, B., and
              N. Agarwal, "OpenID Connect Session Management 1.0",
              August 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.

   [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.

   [USA15]    Davis, M., Whistler, K., and

   [RFC6749]  Hardt, D., "The OAuth 2.0 Authorization Framework",
              RFC 6749, October 2012.

   [RFC6750]  Jones, M. Duerst, "Unicode
              Normalization Forms", Unicode Standard Annex 15, 09 2009.

   [hostmeta]
              Hammer-Lahav, E., "Web Host Metadata", 2010, <http://
              xml.resource.org/public/rfc/bibxml3/
              reference.I-D.draft-hammer-hostmeta-13.xml>.

8.2.  Non-Normative References

   [UMA-Core]
              Scholz, C., "UMA Requirements", 2010, <http://
              tools.ietf.org/id/draft-hardjono-oauth-umacore-04.txt>.

   [UMA-Reqs]
              Maler, E., "UMA Requirements", 2010, <http://
              kantarainitiative.org/confluence/display/uma/
              UMA+Requirements>.

   [UMA-UC]   Akram, H., "UMA Explained", 2010, <http://
              kantarainitiative.org/confluence/display/uma/
              UMA+Scenarios+and+Use+Cases>. 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:

   Thomas Hardjono
   MIT

   Phone:
   Fax:
   Email: hardjono@mit.edu
   URI:

   Maciej Machulak
   Newcastle University

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

   Eve Maler
   XMLgrrl.com

   Email: eve@xmlgrrl.com
   URI:   http://www.xmlgrrl.com
   Christian Scholz
   COM.lounge GmbH

   Phone:
   Fax:
   Email:
   URI:

   Nat Sakimura
   Nomura Research Institute, Ltd.

   Email: n-sakimura@nri.co.jp

   John Bradley
   Ping Identity

   Email: ve7jtb@ve7jtb.com
   Michael B. Jones
   Microsoft

   Email: mbj@microsoft.com

   Maciej Machulak
   Newcastle University

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