Network Working Group                                     J. Richer, Ed.
Internet-Draft                                     The MITRE Corporation
Intended status: Standards Track                              J. Bradley
Expires: July 11, August 10, 2013                                   Ping Identity
                                                                M. Jones
                                                               Microsoft
                                                             M. Machulak
                                                    Newcastle University
                                                         January 7,
                                                        February 6, 2013

               OAuth Dynamic Client Registration Protocol
                      draft-ietf-oauth-dyn-reg-04
                      draft-ietf-oauth-dyn-reg-05

Abstract

   This specification defines an endpoint and protocol for dynamic
   registration of OAuth 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 July 11, August 10, 2013.

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

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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
     1.1.  Notational Conventions . . . . . . . . . . . . . . . . . .  3
     1.2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . .  3
     1.3.  Requirements
   2.  Client Metadata  . . . . . . . . . . . . . . . . . . . . . . .  4
       1.3.1.  The client needs to be uniquely identifiable by
               the authorization server
   3.  Client Registration Endpoint . . . . . . . . . . . . . . .  4
       1.3.2.  The authorization server must collect metadata
               about a client for later user interaction . .  7
     3.1.  Client Registration Request  . . . . . . . .  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 . . . . . .  8
     3.2.  Client Registration Response . . . . . . . . . . . . . . .  4
       1.3.5.  Transaction integrity must be ensured  8
     3.3.  Client Registration Error Response . . . . . . . . .  5
   2.  Client Metadata . . . 10
   4.  Client Update Endpoint . . . . . . . . . . . . . . . . . . . .  5
   3. 11
     4.1.  Client Registration Endpoint Update Request  . . . . . . . . . . . . . . . . .  8
     3.1. . 12
     4.2.  Client Registration Read Request  . . . . . . . . . . . . . . .  9
     3.2. . . . . 12
     4.3.  Client Registration Update or Read Response . . . . . . . . . . . . . . . 10
     3.3. 13
     4.4.  Client Update Delete Request  . . . . . . . . . . . . . . . . . . 11
     3.4. 14
   5.  Client Update Response Secret Rotation . . . . . . . . . . . . . . . . . . 13
     3.5. . . 15
     5.1.  Rotate Secret Request  . . . . . . . . . . . . . . . . . . 13
     3.6. 15
     5.2.  Rotate Secret Response . . . . . . . . . . . . . . . . . . 14
     3.7.  Client Registration Error Response . . . . . . . . . . . . 15
   4.
   6.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 16
   5.
   7.  Security Considerations  . . . . . . . . . . . . . . . . . . . 16
   6.
   8.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 17
   7. 18
   9.  Document History . . . . . . . . . . . . . . . . . . . . . . . 17
   8. 18
   10. Normative References . . . . . . . . . . . . . . . . . . . . . 18 20
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 19 20

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 requiring the two parties to interact before hand.
   Nevertheless, in order 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 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 [RFC6749].

   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 registration.

   o  Client Update Endpoint: The OAuth 2.0 Endpoint through which a
      specific Client can manage its registration information, provided
      by the metadata
      associated with it. Authorization Server to the Client.

   o  Client Secret Rotation Endpoint: The OAuth 2.0 Endpoint through
      which a specific Client can request refreshes of its Client Secret
      and Registration Access Token.

   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 token is intended for discussion and will
   likely be removed in associated with a
      particular Client.

2.  Client Metadata

   Clients generally have an array of metadata associated with their
   unique Client Identifier at the final draft. ]]

1.3.1.  The Authorization Server.  These can
   range from human-facing display strings, such as a client needs name, to be uniquely identifiable by
   items that impact 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, security of the client
   identifier (and optional secret) should thus be issued by protocol, such as the
   authorization server list of
   valid redirect URIs.

   Extensions and not simply accepted as proposed 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.

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

   In order for Client that it does not understand.

   [[ Editor's note: normative language in the authorization server table below is meant to describe a client
   apply to an end-
   user in an authorization step it needs information about the client.
   This can be *client* when sending the client name at a minimum, but today servers usually
   request request.  The paragraph above
   is meant to say that the server must at least a description, a homepage URL, accept all parameters
   and not fail with an icon when
   doing manual registration.

1.3.3.  The authorization server should have error at an unknown parameter, especially if
   it's in the option list below.  Also, extensions need to explicitly call out
   if they're not going to do something with one of these basic
   parameters instead of strongly
        authenticating just ignoring their existence.  This is meant
   to be the client *minimum set* of parameters for interoperability. ]]

   redirect_uris
      RECOMMENDED.  A list of redirect URIs for use in the Authorization
      Code and its metadata

   In order to prevent spoofing Implicit grant types.  An Authorization Server SHOULD
      require registration of valid redirect URIs for all clients that
      use these grant types in order to protect against token and enable dynamic building
      credential theft attacks.

   client_name
      RECOMMENDED.  Human-readable name 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 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
      RECOMMENDED.  A space-delimited list of redirect URIs for use in
      the Authorization Code and Implicit grant types.  An Authorization
      Server SHOULD require registration of valid redirect URIs for all
      clients to protect against token and credential theft attacks.

   client_name
      RECOMMENDED.  Human-readable name of the Client Client to be presented to
      the user.  If omitted, the Authorization Server MAY display to the
      user the raw client_id "client_id" value instead.

   client_url
      RECOMMENDED.  URL of the homepage of the Client.  If present, the
      server SHOULD display this URL to the end user in a clickable
      fashion.

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

   contacts
      OPTIONAL.  Space delimited list  List of email addresses for people responsible for this client.
      Client.  The Authorization Server MAY may make these addresses
      available to end users for support queries. requests for the Client.  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 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_type

   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 symmetric secret issued by the server

      *  "private_key_jwt": the client uses the JWT Assertion profile
         with its own private key

      Other Authentication authentication methods may be defined by extension.  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.

   scope
      OPTIONAL.  Space separated list of scopes (as described in OAuth
      2.0 Section 3.3 [RFC6749]) that the client will be allowed to
      request tokens for.  If omitted, an Authorization Server MAY
      register a Client with a default set of allowed scopes.

   grant_type
      OPTIONAL.  Space separated list  List of grant types that a client may use.  These grant
      types are defined as follows:

      *  "authorization_code": The Authorization Code Grant described in
         OAuth2 Section 4.1.

      *  "implicit": The Implicit Grant described in OAuth2 Section 4.2.

      *  "password": The Resource Owner Password Credentials Grant
         described in OAuth2 Section 4.3

      *  "client_credentials": The Client Credentials Grant described in
         OAuth2 Section 4.4

      *  "refresh_token": The Refresh Token Grant described in OAuth2
         Section 6.

      Authorization Servers MAY allow for other values as defined in
      grant type extensions to OAuth2.  The extension process is
      described in OAuth2 Section 2.5, and the value of this parameter
      MUST be the same as the value of the grant_type "grant_type" parameter
      defined in the extension.

   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 requests, such as requests to the Token
      Endpoint using the "private_key_jwt" assertion client credential.
      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 the server
      can use to encrypt 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.

   x509_url
      OPTIONAL.  URL for the Client's PEM encoded X.509 Certificate or
      Certificate chain that is used for signing requests, such as
      requests to the Token Endpoint using the "private_key_jwt"
      assertion client credential.  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 the server can use to encrypt responses to
      the Client.  If the Client registers both "jwk_encryption_url" and
      "x509_encryption_url", the keys contained in both formats SHOULD MUST be
      the same.

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" "application/json" format.  The Client
   Registration Endpoint MUST be protected by a transport-
   layer 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 Endpoint defines three operations that a client can take on it,
   switched by the "operation" parameter:

   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": requst a new Registration Access Token and, if
      applicable, a Client Secret for a Client

   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.

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

   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. connections to the
   Client Update Endpoint.  As such, the Client Update Endpoint MUST
   accept requests with OAuth 2.0 Bearer Tokens [RFC6750] for these
   operations, whether or not the initial
   "client_register" registration call requires
   authentication of some form.

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

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

3.1.  Client Registration Request

   This operation
      REQUIRED.  Valid values are "client_register", "rotate_secret",
      and "client_update", as described above.

   access_token
      OPTIONAL.  An OAuth2 Bearer token used registers a new Client to access the Authorization Server.
   The Authorization Server assigns this client a unique Client
      Registration Endpoint, as defined in OAuth2 Bearer [RFC6750].
      This parameter MUST NOT be sent if
   Identifier, optionally assigns a Client Secret, and associates the Access Token is sent
   metadata given in the
      HTTP Authorization header as request with the issued Client Identifier.  The
   request includes any parameters described in Section 7.1 of OAuth 2.0
      [RFC6749].  Access Tokens sent 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 authorization header must be
      OAuth 2.0 Bearer Tokens [RFC6750].

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

   The Client sends an HTTP POST to the Client Registration Endpoint MUST ignore
   with a content type of "application/json" and all parameters it does
   not understand.

3.1.  Client Registration as top-
   level members of a JSON object.

   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/json
   Host: server.example.com

   {
    "redirect_uris":["https://client.example.org/callback",
       "https://client.example.org/callback2"]
    "client_name":"My Example Client",
    "token_endpoint_auth_method":"client_secret_basic",
    "scope":"read write dolphin",
    "logo_url":"https://client.example.org/logo.png",
    "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, if applicable, a
   Client Secret.

   Additionally, the Authorization Server SHOULD 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 request and substitute them
   with suitable values.  If the Authorization Server performs any such
   substitutions to the requested values, it MUST return these values in
   the response.

   The response contains a "_links" structure which contains fully
   qualified URLs to the Client Update Endpoint and the Client Secret
   Rotation Endpoint for this specific client.  The response also
   contains a Registration Access Token that is to be used by the client
   to perform subsequent operations at the Client Update Endpoint and
   the Client Secret Rotation Endpoint.

   The response is an "application/json" document with the following
   parameters in addition to any applicable client metadata fields as
   top-level members of a JSON object [RFC4627] .

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

   client_secret
      OPTIONAL.  The Client secret.  If issued, this MUST be unique for
      each "client_id".  This value is used by confidential clients to
      authenticate to the Token Endpoint as described in OAuth 2.0
      Section 2.3.1.

   registration_access_token
      REQUIRED.  The Access token to be used by the client to perform
      actions on the Client Update Endpoint and the Client Secret
      Rotation Endpoint.

   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
      REQUIRED if "client_secret" is issued.  The number of seconds from
      1970-01-01T0:0:0Z as measured in UTC that the "client_secret" will
      expire or "0" if it does not expire.  See RFC 3339 [RFC3339] for
      details regarding date/times in general and UTC in particular.

   _links
      REQUIRED.  A JSON object that contains references to the Client
      Update Endpoint and Client Secret Rotation Endpoint, via the
      following members:

      self  REQUIRED.  A JSON object that contains the member href which
         contains the fully qualified URL of the Client Update Endpoint
         for this client.  This MAY be constructed using a URL Template
         of the Client Registration Endpoint with the issued client_id.

      rotate_secret  REQUIRED.  A JSON object that contains the member
         href which contains the fully qualified URL of the Client
         Secret Rotation Endpoint for this client.  This MAY be
         constructed using a URL Template of the Client Registration
         Endpoint with the issued client_id.

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

   {
    _links: {
      "self": {
        "href":
          "https://server.example.com/register/s6BhdRkqt3"
      },
      "rotate_secret": {
        "href":
          "https://server.example.com/register/rotate_secret/s6BhdRkqt3"
      }
    "redirect_uris":["https://client.example.org/callback",
       "https://client.example.org/callback2"]
    "client_id":"s6BhdRkqt3",
    "client_secret": "cf136dc3c1fc93f31185e5885805d",
    "scope": "read write dolphin",
    "grant_type": ["authorization_code", "refresh_token"]
    "token_endpoint_auth_method": "client_secret_basic",
    "logo_url": "https://client.example.org/logo.png",
    "jwk_url": "https://client.example.org/my_rsa_public_key.jwk",
    "registration_access_token": "reg-23410913-abewfq.123483",
    "expires_at":2893276800
   }

3.3.  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
   [RFC4627] 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_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

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

4.  Client Update Endpoint

   The Client Update Endpoint is an OAuth 2.0 protected endpoint that is
   provisioned by the server for a specific client to be able to view
   and update its registered information.  It is RECOMMENDED that this
   endpoint URL be formed through the use of a URL template which
   combines the Client Registration Endpoint and the issued client_id
   for this client, either as a path parameter
   (https://server.example.com/register/client_id) or as a query
   parameter (https://server.example.com/register/?update=client_id).
   The Authorization Server MUST provide the client with the fully
   qualified URL in the _links structure described in section 3 and MUST
   NOT require the client to construct this URL on its own.

   The Authorization Server MUST be able to determine the appropriate
   client_id from the context of the request without requiring the
   Client to explicitly send its own "client_id" in the request.

   Operations on this endpoint are switched through the use of specific
   HTTP verbs.

4.1.  Client Update Request

   This operation registers updates a new previously-registered client to with new
   metadata at 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  This request with is authenticated
   by the Registration Access Token issued Client Identifier. to the client.

   The Client makes an HTTP PUT request includes to the two parameters described above as well as Client Update Endpoint
   with a content type of "application/json".  This request MAY include
   any
   parameters fields described in Client Metadata (Section 2).  The
   Authorization Server MAY provision default values for any items
   omitted  If included in
   the request, valid values of Client Metadata.

   operation
      REQUIRED. Metadata fields in this request
   MUST have replace, not augment, the values previously associated with this
   Client.  Any fields with the value "client_register"
   access_token
      OPTIONAL.  OAuth2 Access token used to restrict new client
      registration.  This parameter of a JSON "null" in Client
   Metadata MUST NOT be sent if the Access Token
      is sent taken as a request to clear any existing value of
   that field.  Omitted values in the HTTP Client Metadata MUST remain
   unchanged by the Authorization header as described in Section
      7.1 of OAuth 2.0 [RFC6749].  Access Tokens sent Server.  The Authorization Server MAY
   replace any invalid values with suitable values, and it MUST return
   any such fields to the Client in the
      authorization header must be OAuth 2.0 Bearer Tokens [RFC6750].
   redirect_uris  RECOMMENDED
   client_name  RECOMMENDED
   client_url  RECOMMENDED
   logo_url  OPTIONAL
   contacts  OPTIONAL
   tos_url  OPTIONAL
   token_endpoint_auth_type  OPTIONAL
   policy_url  OPTIONAL
   scope  OPTIONAL
   grant_type  OPTIONAL
   jwk_url  OPTIONAL
   jwk_encryption_url  OPTIONAL
   x509_url  OPTIONAL
   x509_encryption_url  OPTIONAL response.

   For example, a client could send the following registration following request to the Client
   Registration Endpoint to update the client registration in the above
   example:

   Following is a non-normative example request (with line wraps for
   display purposes only):
   PUT /register/s6BhdRkqt3 HTTP/1.1
   Accept: application/json
   Host: server.example.com
   Authorization: Bearer reg-23410913-abewfq.123483

   {
    "redirect_uri":["https://client.example.org/callback",
       "https://client.example.org/alt"],
    "client_name":"My New Example",
    "logo_url":"https://client.example.org/newlogo.png"
   }

4.2.  Client Read Request

   In order to read the current configuration of the Client on the
   Authorization Server, the Client makes an HTTP GET request to the
   Client Update Endpoint with the Registration Endpoint: Access Token.

   Following is a non-normative example request (with line wraps for
   display purposes only):
   POST /register
   GET /register/s6BhdRkqt3 HTTP/1.1
   Accept: application/x-www-form-urlencoded application/json
   Host: server.example.com

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

3.2.
   Authorization: Bearer reg-23410913-abewfq.123483

4.3.  Client Registration Update or Read Response

   Upon successful registration, update or read operation, the Client Registration Update Endpoint
   returns the newly-created Client Identifier and, if applicable, a Client Secret, along with ID.  Additionally, the Authorization Server SHOULD
   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 field metadata values submitted during an update request and
   substitute them with suitable values.  If this happens, the Authorization Server
   performs any such substitutions to the requested values, it MUST include
   return these
   fields values in the response to the client. response.

   The response also contains a Registration Authorization Server MUST NOT include the Client Secret or
   Request Access Token that is to be
   used by the client to perform subsequent operations at in this endpoint,
   such as "client_update" and "rotate_secret".

   All of the response.

   The response items are returned as is a JSON document Document [RFC4627] with the following fields
   as well as any applicable client metadata as top-level members of the root a
   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 equal the value is used by confidential clients to
      authenticate to of
      the Token Endpoint as described client_id returned in OAuth 2.0
      Section 2.3.1.

   registration_access_token the original client_register request.

   _links
      REQUIRED.  The Access token  A JSON object that contains references to be used by the client to perform
      "client_update" Client
      Update Endpoint and "rotate_secret" requests.

   issued_at
      OPTIONAL.  Specifies Client Secret Rotation Endpoint, via the timestamp when
      following members:

      self  REQUIRED.  A JSON object that contains the member href which
         contains the fully qualified URL of the Client Update Endpoint
         for this client.  This MAY be constructed using a URL Template
         of the Client Registration Endpoint with the issued client_id.

      rotate_secret  REQUIRED.  A JSON object that contains the member
         href which contains the fully qualified URL of the Client Identifier was
      issued.  The timestamp value MUST
         Secret Rotation Endpoint for this client.  This MAY be
         constructed using 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 URL Template 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. Client Registration
         Endpoint with the issued client_id.

   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": "cf136dc3c1fc93f31185e5885805d",
    _links: {
      "self": {
        "href": "https://server.example.com/register/s6BhdRkqt3"
      },
      "rotate_secret": {
        "href": "https://server.example.com/register/s6BhdRkqt3/secret"
      }
    "client_id": "s6BhdRkqt3",
    "client_name": "My New Example",
    "redirect_uri": ["https://client.example.org/callback",
      "https://client.example.org/alt"]
    "scope": "read write dolphin",
    "grant_type": "authorization_code refresh_token",
   "token_endpoint_auth_type": "client_secret_basic client_secret_post", ["authorization_code", "refresh_token"],
    "token_endpoint_auth_method": "client_secret_basic",
    "logo_url": "https://client.example.org/logo.png", "https://client.example.org/newlogo.png",
    "jwk_url": "https://client.example.org/my_rsa_public_key.jwk",
   "registration_access_token": "reg-23410913-abewfq.123483",
   "expires_at":2893276800
   }

3.3.

4.4.  Client Update Delete 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).  If included in the request, valid 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

   In order to clear any existing value of
   that field.  Omitted values in the Client Metadata MUST remain
   unchanged by the Authorization Server.  The Authorization Server MAY
   replace any invalid values with suitable values.

   operation
      REQUIRED, MUST have the value "client_update"
   access_token
      REQUIRED, unless presented in deprovision itself on 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  RECOMMENDED
   client_name  RECOMMENDED
   client_url  RECOMMENDED
   logo_url  OPTIONAL
   contacts  OPTIONAL
   tos_url  OPTIONAL
   token_endpoint_auth_type  OPTIONAL
   policy_url  OPTIONAL
   jwk_url  OPTIONAL
   jwk_encryption_url  OPTIONAL
   x509_url  OPTIONAL
   x509_encryption_url  OPTIONAL
   For example, a client could send Server, the following
   Client makes an HTTP DELETE request to the Client
   Registration Update Endpoint to update
   with the client registration in Registration Access Token.  This request is authenticated by
   the above
   example: Registration Access Token issued to the client.

   Following is a non-normative example request (with line wraps for
   display purposes only):
   POST /register
   DELETE /register/s6BhdRkqt3 HTTP/1.1
   Accept: application/x-www-form-urlencoded application/json
   Host: server.example.com
   Authorization: Bearer reg-23410913-abewfq.123483

   operation=client_update
   &redirect_uri=https://client.example.org/callback
       %20https://client.example.org/alt
   &client_name=My%20New%20Example%20
   &logo_url=https://client.example.org/newlogo.png

3.4.  Client Update Response

   Upon successful update,

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

   Following is a non-normative example response:
   HTTP/1.1 204 No Content
   Cache-Control: no-store

5.  Client Registration Secret Rotation

   The Client Secret Rotation Endpoint returns is an OAuth 2.0 protected
   endpoint that is provisioned by the server for a specific client to
   be able to request rotation of its Registration Access Token and, if
   it has one, Client ID, along with all current registered metadata (Section 2)
   about Secret.  It is RECOMMENDED that this client, including any fields provisioned by endpoint URL
   be formed through the
   Authorization Server itself.  The Authorization Server MAY reject or
   replace any use of a URL template which combines the client's requested field values Client
   Registration Endpoint and substitute
   them suitable values.  If this happens, the issued client_id for this client,
   either as a path parameter
   (https://server.example.com/register/rotate_secret/client_id) or as a
   query parameter
   (https://server.example.com/register/?rotate_secret=client_id).  The
   Authorization Server MUST
   include these fields in provide the response to client with the client.

   The Authorization Server fully qualified
   URL in the _links structure described in section 3, and MUST NOT include
   require the Client Secret or
   Request Access Token in to construct this response.

   These fields are returned in a JSON Document [RFC4627] as top-level
   members of the root JSON object.

   client_id
      REQUIRED. URL on its own.

   The unique Client identifier, Authorization Server MUST equal the value of be able to determine the appropriate
   client_id returned in from 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",
   "client_name": "My New Example",
   "redirect_uri":
  "https://client.example.org/callback https://client.example.org/alt"
   "scope": "read write dolphin",
   "grant_type": "authorization_code refresh_token",
   "token_endpoint_auth_type": "client_secret_basic client_secret_post",
   "logo_url": "https://client.example.org/newlogo.png",
   "jwk_url": "https://client.example.org/my_rsa_public_key.jwk",
  }

3.5. context of the request without requiring the
   Client to explicitly send its own "client_id" in the request.

5.1.  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.

   operation
      REQUIRED.  MUST have the value rotate_secret

   access_token
      REQUIRED, unless presented in the Authorization Header as in
      OAuth2 Bearer [RFC6750].  The client
   sends an HTTP POST with its current Registration Access Token.  This
   request is authenticated by the Registration Access Token that was issued during to
   the "client_register" step, or previous
      "client_update" or "rotate_secret" calls. client.

   Following is a non-normative example request (with line wraps for
   display purposes only):
   POST /register /register/rotate_secret/s6BhdRkqt3 HTTP/1.1
   Accept: application/x-www-form-urlencoded application/json
   Host: server.example.com
   Authorization: Bearer reg-23410913-abewfq.123483

   operation=rotate_secret

3.6.

5.2.  Rotate Secret Response

   Upon successful rotation of the Registration Access Token, and
   optionally the Client Secret, the Client Registration Endpoint
   returns a JSON document [RFC4627] with the following fields as top-
   level members of the root JSON object.  This response MUST NOT
   include any other client metadata.

   client_id
      REQUIRED.  The unique Client identifier, MUST match the client_id
      issued in the original client_register registration 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
      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
      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": "7fce6c93f31185e5885805d",
     "registration_access_token": "reg-02348913-oieqer.983421",
    "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
   [RFC4627] 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 was issued.
      The timestamp value of "operation" is invalid or not supported.

   invalid_redirect_uri MUST be a positive integer.  The value of one or more "redirect_uris" is invalid.

   invalid_client_metadata
      The value of one of
      expressed in the client metadata (Section 2) fields is
      invalid and number of seconds since January 1, 1970 00:00:00
      GMT.

   expires_at
      REQUIRED if the server has rejected this request.  Note that an
      Authorization server MAY choose to substitute issues a valid value for
      any requested parameter Client Secret.  The number of a client's metadata.
      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 of an error response (with line
   wraps for display purposes only): 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
    "client_id":"s6BhdRkqt3",
    "client_secret": "7fce6c93f31185e5885805d",
     "registration_access_token": "reg-02348913-oieqer.983421",
    "expires_at":2893276800
   }

   The Authorization Server SHOULD discard and invalidate the operation parameter must
     be one Request
   Access Token and the Client Secret associated with this Client after
   successful completion of client_register, rotate_secret or client_update."
   }

4. this request.

6.  IANA Considerations

   This document makes no requests of IANA.

5.

7.  Security Considerations

   [[ Editor's note: Following are some security considerations taken
   from the UMA and OpenID Connect source drafts.  These need to be
   massaged into a properly generic set of considerations. ]]

   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
   Server could warn if the domain/site of the logo doesn't match the
   domain/site of redirect URIs.  An Authorization Server can also
   present warning messages to end users about untrusted Clients in all
   cases, especially if such clients have been dynamically registered
   and 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.
   Since the Registration Access Token is a Bearer token and acts as the
   sole authentication for use at the Client Update Endpoint, it MUST be
   protected by the Client as described in OAuth 2.0 Bearer [RFC6750].

8.  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.

9.  Document History

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

   - 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

   - 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

8.

10.  Normative References

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

   [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.

   [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

   Michael B. Jones
   Microsoft

   Email: mbj@microsoft.com

   Maciej Machulak
   Newcastle University

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