One document matched: draft-ietf-oauth-dyn-reg-04.xml

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<rfc category="std" docName="draft-ietf-oauth-dyn-reg-04" ipr="trust200902">
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  <front>
    <title abbrev="oauth-dyn-reg">OAuth Dynamic Client Registration
    Protocol</title>

    <author fullname="Justin Richer" initials="J" role="editor"
            surname="Richer">
      <organization>The MITRE Corporation</organization>

      <address>
        <postal>
          <street/>

          <city/>

          <region/>

          <code/>

          <country/>
        </postal>

        <phone/>

        <facsimile/>

        <email>jricher@mitre.org</email>

        <uri/>
      </address>
    </author>

    <author fullname="John Bradley" initials="J." surname="Bradley">
      <organization abbrev="Ping Identity">Ping Identity</organization>

      <address>
        <email>ve7jtb@ve7jtb.com</email>
      </address>
    </author>

    <author fullname="Michael B. Jones" initials="M.B." surname="Jones">
      <organization abbrev="Microsoft">Microsoft</organization>

      <address>
        <email>mbj@microsoft.com</email>
      </address>
    </author>

    <author fullname="Maciej Machulak" initials="M" surname="Machulak">
      <organization>Newcastle University</organization>

      <address>
        <email>m.p.machulak@ncl.ac.uk</email>

        <uri>http://ncl.ac.uk/</uri>
      </address>
    </author>

    <date day="7" month="January" year="2013"/>

    <abstract>
      <t>This specification defines an endpoint and protocol for dynamic
      registration of OAuth Clients at an Authorization Server.</t>
    </abstract>
  </front>

  <middle>
    <section title="Introduction">
      <t>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.</t>

      <t>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.</t>

      <section title="Notational Conventions">
        <t>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 <xref
        target="RFC2119"/>.</t>

        <t>Unless otherwise noted, all the protocol parameter names and values
        are case sensitive.</t>
      </section>

      <section anchor="terminology" title="Terminology">
        <t>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 <xref target="RFC6749">OAuth
        2.0</xref>.</t>

        <t>This specification defines the following additional terms:</t>

        <t><list style="symbols">
            <t>Client Registration Endpoint: The OAuth 2.0 Endpoint through
            which a Client can request new registration and manage the
            metadata associated with it.</t>

            <t>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.</t>
          </list></t>
      </section>

      <section title="Requirements">
        <t>[[ Following are proposed requirements for dynamic client
        registration. This section is intended for discussion and will likely
        be removed in the final draft. ]]</t>

        <section title="The client needs to be uniquely identifiable by the authorization server">
          <t>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.</t>
        </section>

        <section title="The authorization server must collect metadata about a client for later user interaction">
          <t>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.</t>
        </section>

        <section title="The authorization server should have the option of strongly authenticating the client and its metadata">
          <t>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.</t>
        </section>

        <section title="Dynamic client registration must be possible from both web-server applications and applications with other capabilities and limitations, such as native applications">
          <t>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.</t>
        </section>

        <section title="Transaction integrity must be ensured">
          <t>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.</t>
        </section>
      </section>
    </section>

    <section anchor="client-metadata" title="Client Metadata">
      <t>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.</t>

      <t>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.</t>

      <t><list style="hanging">
          <t hangText="redirect_uris"><vspace blankLines="0"/>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.</t>

          <t hangText="client_name"><vspace blankLines="0"/>RECOMMENDED.
          Human-readable name of the Client to be presented to the user. If
          omitted, the Authorization Server MAY display to the user the raw
          client_id value instead.</t>

          <t hangText="client_url"><vspace/>RECOMMENDED. URL of the homepage
          of the Client. If present, the server SHOULD display this URL to the
          end user in a clickable fashion.</t>

          <t hangText="logo_url"><vspace blankLines="0"/>OPTIONAL. URL that
          references a logo for the Client application. If present, the server
          SHOULD display this image to the end user during approval.</t>

          <t hangText="contacts"><vspace blankLines="0"/>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.</t>

          <t hangText="tos_url"><vspace blankLines="0"/>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.</t>

          <t hangText="token_endpoint_auth_type"><vspace
          blankLines="0"/>OPTIONAL. The requested authentication type for the
          Token Endpoint. Valid values are:<list style="symbols">
              <t><spanx style="verb">none</spanx>: this is a public client as
              defined in OAuth 2.0 and does not have a client secret</t>

              <t><spanx style="verb">client_secret_post</spanx>: the client
              uses the HTTP POST parameters defined in OAuth2.0 section
              2.3.1</t>

              <t><spanx style="verb">client_secret_basic</spanx>: the client
              uses HTTP Basic defined in OAuth 2.0 section 2.3.1</t>

              <t><spanx style="verb">client_secret_jwt</spanx>: the client
              uses the JWT Assertion profile with a symmetric secret issued by
              the server</t>

              <t><spanx style="verb">private_key_jwt</spanx>: the client uses
              the JWT Assertion profile with its own private key</t>
            </list>Other Authentication methods may be defined by extension.
          If unspecified or omitted, the default is <spanx style="verb">client_secret_basic</spanx>,
          denoting HTTP Basic Authentication Scheme as specified in Section
          2.3.1 of OAuth 2.0.</t>

          <t hangText="scope"><vspace blankLines="0"/>OPTIONAL. Space
          separated list of scopes 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.</t>

          <t hangText="grant_type"><vspace blankLines="0"/>OPTIONAL. Space
          separated list of grant types that a client may use. These grant
          types are defined as follows:<list style="symbols">
              <t><spanx style="verb">authorization_code</spanx>: The
              Authorization Code Grant described in OAuth2 Section 4.1.</t>

              <t><spanx style="verb">implicit</spanx>: The Implicit Grant
              described in OAuth2 Section 4.2.</t>

              <t><spanx style="verb">password</spanx>: The Resource Owner
              Password Credentials Grant described in OAuth2 Section 4.3</t>

              <t><spanx style="verb">client_credentials</spanx>: The Client
              Credentials Grant described in OAuth2 Section 4.4</t>

              <t><spanx style="verb">refresh_token</spanx>: The Refresh Token
              Grant described in OAuth2 Section 6.</t>
            </list>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 parameter defined in
          the extension.</t>

          <t hangText="policy_url"><vspace blankLines="0"/>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.</t>

          <t hangText="jwk_url"><vspace blankLines="0"/>OPTIONAL. URL for the
          Client's <xref target="JWK">JSON Web Key</xref> document that is
          used for signing requests, such as requests to the Token Endpoint
          using the <spanx style="verb">private_key_jwt</spanx> assertion
          client credential. If the Client registers both <spanx style="verb">x509_url</spanx>
          and <spanx style="verb">jwk_url</spanx>, the keys contained in both
          formats MUST be the same.</t>

          <t hangText="jwk_encryption_url"><vspace blankLines="0"/>OPTIONAL.
          URL for the Client's <xref target="JWK">JSON Web Key</xref> that the
          server can use to encrypt responses to the Client. If the Client
          registers both <spanx style="verb">jwk_encryption_url</spanx> and
          <spanx style="verb">x509_encryption_url</spanx>, the keys contained
          in both formats MUST be the same.</t>

          <t hangText="x509_url"><vspace blankLines="0"/>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 <spanx style="verb">private_key_jwt</spanx> assertion
          client credential. If the Client registers both <spanx style="verb">x509_url</spanx>
          and <spanx style="verb">jwk_url</spanx>, the keys contained in both
          formats MUST be the same.</t>

          <t hangText="x509_encryption_url"><vspace blankLines="0"/>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 <spanx style="verb">jwk_encryption_url</spanx>
          and <spanx style="verb">x509_encryption_url</spanx>, the keys
          contained in both formats SHOULD be the same.</t>
        </list></t>
    </section>

    <section title="Client Registration Endpoint">
      <t>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 <spanx style="verb">application/x-www-form-urlencoded</spanx>
      format. The Client Registration Endpoint MUST be protected by a
      transport-layer security mechanism, and the server MUST support TLS 1.2
      <xref target="RFC5246">RFC 5246</xref> and/or TLS 1.0 <xref
      target="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 <xref
      target="RFC6125">RFC 6125</xref>.</t>

      <t>The Endpoint defines three operations that a client can take on it,
      switched by the <spanx style="verb">operation</spanx> parameter:</t>

      <t><list style="symbols">
          <t><spanx style="verb">client_register</spanx>: request that the
          Authorization Server generate a new Client Identifier (and
          optionally a Client Secret) and associate it with the set of
          presented <xref target="client-metadata">metadata</xref></t>

          <t><spanx style="verb">client_update</spanx>: update the <xref
          target="client-metadata">metadata</xref> associated with a Client
          Identifier</t>

          <t><spanx style="verb">rotate_secret</spanx>: requst a new
          Registration Access Token and, if applicable, a Client Secret for a
          Client</t>
        </list></t>

      <t>The Client Registration Endpoint MAY accept an initial authorization
      credential in the form of an <xref target="RFC6749">OAuth 2.0 </xref>
      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.</t>

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

      <t>In order to facilitate registered clients updating their information,
      the Client Registration Endpoint issues a Request Access Token for
      clients to securely identify themselves in future connections. As such,
      the Endpoint MUST accept requests with <xref target="RFC6750">OAuth 2.0
      Bearer Tokens</xref> for these operations, whether or not the initial
      <spanx style="verb">client_register</spanx> call requires authentication
      of some form.</t>

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

      <t><list style="hanging">
          <t hangText="operation"><vspace blankLines="0"/>REQUIRED. Valid
          values are <spanx style="verb">client_register</spanx>, <spanx
          style="verb">rotate_secret</spanx>, and <spanx style="verb">client_update</spanx>,
          as described above.</t>

          <t hangText="access_token"><vspace blankLines="0"/>OPTIONAL. An
          OAuth2 Bearer token used to access the Client Registration Endpoint,
          as defined in <xref target="RFC6750">OAuth2 Bearer</xref>. This
          parameter MUST NOT be sent if the Access Token is sent in the HTTP
          Authorization header as described in Section 7.1 of <xref
          target="RFC6749">OAuth 2.0</xref>. Access Tokens sent in the
          authorization header must be <xref target="RFC6750">OAuth 2.0 Bearer
          Tokens</xref>.</t>
        </list>Each operation takes a different parameter set, and all
      operations are described below.</t>

      <t>The Client Registration Endpoint MUST ignore all parameters it does
      not understand.</t>

      <section title="Client Registration Request">
        <t>This operation registers a new client to the Authorization Server.
        The Authorization Server assigns this client a unique Client
        Identifier, optionally assigns a Client Secret, and associates the
        metadata given in the request with the issued Client Identifier. The
        request includes the two parameters described above as well as any
        parameters described in <xref target="client-metadata">Client
        Metadata</xref>. The Authorization Server MAY provision default values
        for any items omitted in the Client Metadata.</t>

        <t><?rfc subcompact="yes"?><list style="hanging">
            <t hangText="operation"><vspace/>REQUIRED. MUST have the value
            <spanx style="verb">client_register</spanx></t>

            <t hangText="access_token"><vspace/>OPTIONAL. OAuth2 Access token
            used to restrict new client registration. This parameter MUST NOT
            be sent if the Access Token is sent in the HTTP Authorization
            header as described in Section 7.1 of <xref target="RFC6749">OAuth
            2.0</xref>. Access Tokens sent in the authorization header must be
            <xref target="RFC6750">OAuth 2.0 Bearer Tokens</xref>.</t>

            <t hangText="redirect_uris">RECOMMENDED</t>

            <t hangText="client_name">RECOMMENDED</t>

            <t hangText="client_url">RECOMMENDED</t>

            <t hangText="logo_url">OPTIONAL</t>

            <t hangText="contacts">OPTIONAL</t>

            <t hangText="tos_url">OPTIONAL</t>

            <t hangText="token_endpoint_auth_type">OPTIONAL</t>

            <t hangText="policy_url">OPTIONAL</t>

            <t hangText="scope">OPTIONAL</t>

            <t hangText="grant_type">OPTIONAL</t>

            <t hangText="jwk_url">OPTIONAL</t>

            <t hangText="jwk_encryption_url">OPTIONAL</t>

            <t hangText="x509_url">OPTIONAL</t>

            <t hangText="x509_encryption_url">OPTIONAL</t>
          </list><?rfc subcompact="no"?>For example, a client could send the
        following registration request to the Client Registration
        Endpoint:</t>

        <figure>
          <preamble>Following is a non-normative example request (with line
          wraps for display purposes only):</preamble>

          <artwork><![CDATA[POST /register HTTP/1.1
Accept: application/x-www-form-urlencoded
Host: server.example.com

operation=client_register
&redirect_uris=https://client.example.org/callback
    %20https://client.example.org/callback2
&client_name=My%20Example%20Client
&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
]]></artwork>
        </figure>
      </section>

      <section title="Client Registration Response">
        <t>Upon successful registration, the Client Registration Endpoint
        returns the newly-created Client Identifier and, if applicable, a
        Client Secret, along with all registered <xref
        target="client-metadata">metadata</xref> 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 values and substitute them with suitable values. If
        this happens, the Authorization Server MUST include these fields in
        the response to the client.</t>

        <t>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 <spanx style="verb">client_update</spanx> and <spanx
        style="verb">rotate_secret</spanx>.</t>

        <t>All of the response items are returned as a <xref
        target="RFC4627">JSON document</xref> with the following fields as
        top-level members of the root JSON object.</t>

        <t><list style="hanging">
            <t hangText="client_id"><vspace/>REQUIRED. The unique Client
            identifier, MUST NOT be currently valid for any other registered
            Client.</t>

            <t hangText="client_secret"><vspace/>OPTIONAL. The Client secret.
            This MUST be unique for each <spanx style="verb">client_id</spanx>.
            This value is used by confidential clients to authenticate to the
            Token Endpoint as described in OAuth 2.0 Section 2.3.1.</t>

            <t hangText="registration_access_token"><vspace/>REQUIRED. The
            Access token to be used by the client to perform <spanx
            style="verb">client_update</spanx> and <spanx style="verb">rotate_secret</spanx>
            requests.</t>

            <t hangText="issued_at"><vspace/>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.</t>

            <t hangText="expires_at"><vspace/>OPTIONAL. The number of seconds
            from 1970-01-01T0:0:0Z as measured in UTC that the <spanx
            style="verb">client_secret</spanx> will expire or <spanx
            style="verb">0</spanx> if they do not expire. See <xref
            target="RFC3339">RFC 3339</xref> for details regarding date/times
            in general and UTC in particular.</t>
          </list></t>

        <figure>
          <preamble>Following is a non-normative example response:</preamble>

          <artwork><![CDATA[HTTP/1.1 200 OK
Content-Type: application/json
Cache-Control: no-store

{
 "client_id":"s6BhdRkqt3",
 "client_secret": "cf136dc3c1fc93f31185e5885805d",
 "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/logo.png",
 "jwk_url": "https://client.example.org/my_rsa_public_key.jwk",
 "registration_access_token": "reg-23410913-abewfq.123483",
 "expires_at":2893276800
}]]></artwork>
        </figure>
      </section>

      <section title="Client Update Request">
        <t>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 <xref
        target="client-metadata">Client Metadata</xref>. 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 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.</t>

        <t><?rfc subcompact="yes"?><list style="hanging">
            <t hangText="operation"><vspace/>REQUIRED, MUST have the value
            <spanx style="verb">client_update</spanx></t>

            <t hangText="access_token"><vspace/>REQUIRED, unless presented in
            the Authorization Header as in <xref target="RFC6750">OAuth2
            Bearer</xref>. The Registration Access Token that was issued
            during the <spanx style="verb">client_register</spanx> step, or
            previous <spanx style="verb">client_update</spanx> or <spanx
            style="verb">rotate_secret</spanx> calls.</t>

            <t hangText="redirect_uris">RECOMMENDED</t>

            <t hangText="client_name">RECOMMENDED</t>

            <t hangText="client_url">RECOMMENDED</t>

            <t hangText="logo_url">OPTIONAL</t>

            <t hangText="contacts">OPTIONAL</t>

            <t hangText="tos_url">OPTIONAL</t>

            <t hangText="token_endpoint_auth_type">OPTIONAL</t>

            <t hangText="policy_url">OPTIONAL</t>

            <t hangText="jwk_url">OPTIONAL</t>

            <t hangText="jwk_encryption_url">OPTIONAL</t>

            <t hangText="x509_url">OPTIONAL</t>

            <t hangText="x509_encryption_url">OPTIONAL</t>
          </list><?rfc subcompact="no"?>For example, a client could send the
        following request to the Client Registration Endpoint to update the
        client registration in the above example:</t>

        <figure>
          <preamble>Following is a non-normative example request (with line
          wraps for display purposes only):</preamble>

          <artwork><![CDATA[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_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
]]></artwork>
        </figure>
      </section>

      <section title="Client Update Response">
        <t>Upon successful update, the Client Registration Endpoint returns
        the Client ID, along with all current registered <xref
        target="client-metadata">metadata</xref> 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 values and substitute them suitable values. If this
        happens, the Authorization Server MUST include these fields in the
        response to the client.</t>

        <t>The Authorization Server MUST NOT include the Client Secret or
        Request Access Token in this response.</t>

        <t>These fields are returned in a <xref target="RFC4627">JSON
        Document</xref> as top-level members of the root JSON object.<list
            style="hanging">
            <t hangText="client_id"><vspace/>REQUIRED. The unique Client
            identifier, MUST equal the value of the client_id returned in the
            original client_register request.</t>
          </list></t>

        <figure>
          <preamble>Following is a non-normative example response:</preamble>

          <artwork><![CDATA[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",
}]]></artwork>
        </figure>
      </section>

      <section title="Rotate Secret Request">
        <t>This operation allows the client to rotate its current Registration
        Access Token as well as its Client Secret, if it has one.</t>

        <t><list style="hanging">
            <t hangText="operation"><vspace blankLines="0"/>REQUIRED. MUST
            have the value rotate_secret</t>

            <t hangText="access_token"><vspace/>REQUIRED, unless presented in
            the Authorization Header as in <xref target="RFC6750">OAuth2
            Bearer</xref>. The Registration Access Token that was issued
            during the <spanx style="verb">client_register</spanx> step, or
            previous <spanx style="verb">client_update</spanx> or <spanx
            style="verb">rotate_secret</spanx> calls.</t>
          </list></t>

        <figure>
          <preamble>Following is a non-normative example request (with line
          wraps for display purposes only):</preamble>

          <artwork><![CDATA[POST /register HTTP/1.1
Accept: application/x-www-form-urlencoded
Host: server.example.com
Authorization: Bearer reg-23410913-abewfq.123483

operation=rotate_secret
]]></artwork>
        </figure>
      </section>

      <section title="Rotate Secret Response">
        <t>Upon successful rotation of the Registration Access Token, and
        optionally the Client Secret, the Client Registration Endpoint returns
        a <xref target="RFC4627">JSON document</xref> with the following
        fields as top-level members of the root JSON object. This response
        MUST NOT include any other client metadata.<list style="hanging">
            <t hangText="client_id"><vspace/>REQUIRED. The unique Client
            identifier, MUST match the client_id issued in the original
            client_register request.</t>

            <t hangText="client_secret"><vspace/>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 <spanx
            style="verb">client_id</spanx>.</t>

            <t hangText="registration_access_token"><vspace/>REQUIRED The
            Access token to be used by the client to perform subsequent <spanx
            style="verb">client_update</spanx> and <spanx style="verb">rotate_secret</spanx>
            requests.</t>

            <t hangText="issued_at"><vspace/>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.</t>

            <t hangText="expires_at"><vspace/>OPTIONAL. The number of seconds
            from 1970-01-01T0:0:0Z as measured in UTC that the <spanx
            style="verb">client_secret</spanx> will expire or <spanx
            style="verb">0</spanx> if they do not expire. See <xref
            target="RFC3339">RFC 3339</xref> for details regarding date/times
            in general and UTC in particular.</t>
          </list></t>

        <figure>
          <preamble>Following is a non-normative example response:</preamble>

          <artwork><![CDATA[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
}]]></artwork>
        </figure>

        <t>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.</t>
      </section>

      <section title="Client Registration Error Response">
        <t>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.</t>

        <t>When a registration error condition occurs, the Client Registration
        Endpoint returns a HTTP 400 status code including a <xref
        target="RFC4627">JSON object</xref> describing the error in the
        response body.</t>

        <t>The JSON object contains two members:</t>

        <t><list style="hanging">
            <t hangText="error"><vspace/>The error code, a single ASCII
            string.</t>

            <t hangText="error_description"><vspace/>The additional text
            description of the error for debugging.</t>
          </list></t>

        <t>This specification defines the following error codes:</t>

        <t><list style="hanging">
            <t hangText="invalid_operation"><vspace/>The value of <spanx
            style="verb">operation</spanx> is invalid or not supported.</t>

            <t hangText="invalid_redirect_uri"><vspace/>The value of one or
            more <spanx style="verb">redirect_uris</spanx> is invalid.</t>

            <t hangText="invalid_client_metadata"><vspace/>The value of one of
            the <xref target="client-metadata">client metadata</xref> 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.</t>
          </list></t>

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

          <artwork><![CDATA[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."
}]]></artwork>
        </figure>
      </section>
    </section>

    <section anchor="IANA" title="IANA Considerations">
      <t>This document makes no requests of IANA.</t>
    </section>

    <section title="Security Considerations">
      <t>[[ 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. ]]</t>

      <t>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 <xref target="RFC5246">RFC 5246</xref> and/or TLS
      1.0 <xref target="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 <xref
      target="RFC6125">RFC 6125</xref>.</t>

      <t>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.</t>

      <t>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.</t>

      <t>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. <spanx
      style="verb">logo_url</spanx> and <spanx style="verb">policy_url</spanx>).
      A rogue Client could specify a registration request with a reference to
      a drive-by download in the <spanx style="verb">policy_url</spanx>. The
      Authorization Server should check to see if the <spanx style="verb">logo_url</spanx>
      and <spanx style="verb">policy_url</spanx> have the same host as the
      hosts defined in the array of <spanx style="verb">redirect_uris</spanx>.</t>

      <t>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. ]]</t>
    </section>

    <section title="Acknowledgments">
      <t>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.</t>
    </section>

    <section title="Document History">
      <t>[[ to be removed by RFC editor before publication as an RFC ]]</t>

      <t>- 04</t>

      <t><list style="symbols">
          <t>removed default_acr, too undefined in the general OAuth2 case</t>

          <t>removed default_max_auth_age, since there's no mechanism for
          supplying a non-default max_auth_age in OAuth2</t>

          <t>clarified signing and encryption URLs</t>

          <t>changed token_endpoint_auth_method to token_endpoint_auth_type to
          match OIDC</t>
        </list></t>

      <t>- 03</t>

      <t><list style="symbols">
          <t>added scope and grant_type claims</t>

          <t>fixed various typos and changed wording for better clarity</t>

          <t>endpoint now returns the full set of client information</t>

          <t>operations on client_update allow for three actions on metadata:
          leave existing value, clear existing value, replace existing value
          with new value</t>
        </list></t>

      <t>- 02</t>

      <t><list style="symbols">
          <t>Reorganized contributors and references</t>

          <t>Moved OAuth references to RFC</t>

          <t>Reorganized model/protocol sections for clarity</t>

          <t>Changed terminology to "client register" instead of "client
          associate"</t>

          <t>Specified that client_id must match across all subsequent
          requests</t>

          <t>Fixed RFC2XML formatting, especially on lists</t>
        </list></t>

      <t>- 01</t>

      <t><list style="symbols">
          <t>Merged UMA and OpenID Connect registrations into a single
          document</t>

          <t>Changed to form-paramter inputs to endpoint</t>

          <t>Removed pull-based registration</t>
        </list></t>

      <t>- 00</t>

      <t><list style="symbols">
          <t>Imported original UMA draft specification</t>
        </list></t>
    </section>
  </middle>

  <back>
    <references title="Normative References">
      <?rfc include='http://xml.resource.org/public/rfc/bibxml/reference.RFC.2119.xml' ?>

      <?rfc include="http://xml.resource.org/public/rfc/bibxml/reference.RFC.2246.xml"?>

      <?rfc include="http://xml.resource.org/public/rfc/bibxml/reference.RFC.3339.xml"?>

      <?rfc include="http://xml.resource.org/public/rfc/bibxml/reference.RFC.5246.xml"?>

      <?rfc include="http://xml.resource.org/public/rfc/bibxml/reference.RFC.6125.xml"?>

      <?rfc include='http://xml.resource.org/public/rfc/bibxml/reference.RFC.6749.xml'?>

      <?rfc include='http://xml.resource.org/public/rfc/bibxml/reference.RFC.6750.xml'?>

      <?rfc include='http://xml.resource.org/public/rfc/bibxml/reference.RFC.4627.xml'?>

      <reference anchor="JWK">
        <front>
          <title>JSON Web Key (JWK)</title>

          <author fullname="Michael B. Jones" initials="M.B." surname="Jones">
            <organization>Microsoft</organization>
          </author>

          <date day="12" month="May" year="2012"/>
        </front>

        <format target="http://tools.ietf.org/html/draft-ietf-jose-json-web-key"
                type="HTML"/>
      </reference>
    </references>
  </back>
</rfc>