One document matched: draft-ietf-oauth-dyn-reg-18.xml


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<rfc category="std" docName="draft-ietf-oauth-dyn-reg-18" ipr="trust200902">
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  <front>
    <title abbrev="OAuth 2.0 Dynamic Registration">OAuth 2.0 Dynamic Client
    Registration Protocol</title>

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

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

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

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

        <uri>http://self-issued.info/</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="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>

    <author fullname="Phil Hunt" initials="P" surname="Hunt">
      <organization>Oracle Corporation</organization>

      <address>
        <email>phil.hunt@yahoo.com</email>
      </address>
    </author>

    <date day="3" month="July" year="2014"/>

    <area>Security</area>

    <workgroup>OAuth Working Group</workgroup>

    <abstract>
      <t>This specification defines mechanisms for dynamically registering
      OAuth 2.0 clients with authorization servers.
      Registration requests send a set of desired client metadata values
      to the authorization server and the resulting registration responses return
      a client identifier to use at the authorization server and the
      client metadata values registered for the client.
      The client can then use this registration information to communicate with
      the authorization server using the OAuth 2.0 protocol.
      This specification also defines a set of common client
      metadata fields and values for clients to use during registration.
      </t>
    </abstract>
  </front>

  <middle>
    <section anchor="Introduction" title="Introduction">
      <t>In order for an OAuth 2.0 client to utilize an OAuth 2.0
      authorization server, the client needs specific information to interact
      with the server, including an OAuth 2.0 client identifier to use at that server.
      This specification describes how an OAuth 2.0 client can be dynamically
      registered with an authorization server to obtain this information.</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 set of valid redirection URIs. This metadata
      can either be communicated in a self-asserted fashion or as a set of
      metadata called a software statement, which is digitally signed or MACed; in
      the case of a software statement, the issuer is
      vouching for the validity of the data about the client.</t>

      <t>Traditionally, registration of a client with an authorization server
      is performed manually. The mechanisms defined in this specification can
      be used either for a client to dynamically register itself with
      authorization servers or for a client developer to programmatically
      register the client with authorization servers.</t>

      <section anchor="Notation" 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", "authorization code",
	  "authorization endpoint", "authorization grant", "authorization server",
	  "client", "client identifier", "client secret",
	  "grant type", "protected resource", "redirection URI", "refresh token",
	  "resource owner", "resource server", "response type", and "token endpoint"
	  defined by <xref target="RFC6749">OAuth 2.0</xref>
	  and uses the term "Claim" defined by
	  <xref target="JWT">JSON Web Token (JWT)</xref>.
	</t>

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

        <t><list style="hanging">
            <t hangText="Client Developer">
	      <vspace/>
	      The person or organization that
            builds a client software package and prepares it for
            distribution.</t>

            <t hangText="Client Instance">
	      <vspace/>
	      A deployed instance of a piece of
            client software.</t>

            <t hangText="Client Software">
	      <vspace/>
	      Software implementing an OAuth 2.0
            client.</t>

            <t hangText="Client Registration Endpoint">
	      <vspace/>
	      OAuth 2.0 endpoint
            through which a client can be registered at an authorization
            server. The means by which the URL for this endpoint is obtained
            are out of scope for this specification.</t>

            <t hangText="Initial Access Token">
	      <vspace/>
	      OAuth 2.0 access token
	      optionally issued by an authorization server
	      to a developer or client
	      and used to authorize
	      calls to the client registration endpoint. The type and format of
	      this token are likely service-specific and are out of scope for
	      this specification. The means by which the authorization server
	      issues this token as well as the means by which the registration
	      endpoint validates this token are out of scope for this
	      specification.
	      Use of an initial access token is required when
	      the authorization server limits the parties that can register a client.
	    </t>

            <t hangText="Deployment Organization">
	      <vspace/>
	      An administrative security
            domain under which, a software API is deployed and protected by an
            OAuth 2.0 framework. In simple cloud deployments, the software API
            publisher and the deployment organization may be the same. In
            other scenarios, a software publisher may be working with many
            different deployment organizations.</t>

            <t hangText="Software API Deployment">
	      <vspace/>
	      A deployed instance of a
            software API that is protected by OAuth 2.0 in a particular
            deployment organization domain. For any particular software API,
            there may be one or more deployments. A software API deployment
            typically has an associated OAuth 2.0 authorization server as well
            as a client registration endpoint. The means by which endpoints
            are obtained are out of scope for this specification.</t>

            <t hangText="Software API Publisher">
	      <vspace/>
	      The organization that defines
            a particular web accessible API that may deployed in one or more
            deployment environments. A publisher may be any commercial,
            public, private, or open source organization that is responsible
            for publishing and distributing software that may be protected via
            OAuth 2.0. In some cases a software API publisher and a client
            developer may be the same organization.</t>

            <t hangText="Software Statement">
	      <vspace/>
	      Digitally signed or MACed JSON Web Token
	      (JWT) <xref target="JWT"/> that asserts metadata values about the
	      client software.
	      In some cases, a software statement will be issued directly by
	      the organization or developer that creates the client software.
	      In other cases, a software statement will be issued by
	      a third party organization for use by
	      the organization or developer that creates the client software.
	      In both cases, the trust relationship the authorization server
	      has with the issuer of the software statement is intended to be used as
	      an input to the evaluation of whether the registration request is accepted.
	      A software statement can be presented to an authorization server
	      as part of a client registration request.
	    </t>
          </list></t>
      </section>

      <section anchor="ProtocolFlow" title="Protocol Flow">
        <figure>
          <preamble/>

          <artwork><![CDATA[
     +--------(A)- Initial Access Token (OPTIONAL)
     |
     |   +----(B)- Software Statement (OPTIONAL) 
     |   |
     v   v
 +-----------+                                      +---------------+
 |           |--(C)- Client Registration Request -->|    Client     |
 | Client or |                                      | Registration  |
 | Developer |<-(D)- Client Information Response ---|   Endpoint    |
 |           |                                      +---------------+
 +-----------+
]]></artwork>

          <postamble>Figure 1: Abstract Dynamic Client Registration
          Flow</postamble>
        </figure>

        <t>The abstract OAuth 2.0 client dynamic registration flow illustrated
        in Figure 1 describes the interaction between the client or developer
        and the endpoint defined in this specification. This figure does not
        demonstrate error conditions. This flow includes the following
        steps:</t>

        <t><list style="hanging">
            <t hangText="(A)">Optionally, the client or developer is issued an
            initial access token giving access to the client registration
            endpoint. The method by which the initial access token is issued
            to the client or developer is out of scope for this
            specification.</t>

            <t hangText="(B)">Optionally, the client or developer is issued a
            software statement for use with the client registration endpoint.
            The method by which the software statement is issued to the client
            or developer is out of scope for this specification.</t>

            <t hangText="(C)">The client or developer calls the client
            registration endpoint with its desired registration metadata,
            optionally including the initial access token from (A) if one is
            required by the authorization server.</t>

            <t hangText="(D)">The authorization server registers the client
            and returns the client's registered metadata, a client identifier
            that is unique at the server, a set of client credentials such as
            a client secret if applicable for this client, and possibly other
            values.</t>
          </list></t>
      </section>
    </section>

    <section anchor="ClientMetadata" title="Client Metadata">
      <t>Clients have a set of metadata values associated with their client
      identifier at an authorization server, such as the list of valid
      redirection URIs or a display name.</t>

      <t>The client metadata values are used in two ways:</t>

      <t><list style="symbols">
          <t>as input values to registration requests, and</t>

          <t>as output values in registration responses.</t>
        </list></t>

      <t>
	The following client metadata fields are defined by this specification.
	The implementation and use of all client metadata fields is OPTIONAL,
	other than <spanx style="verb">redirect_uris</spanx>.
      </t>

      <t><list style="hanging">
          <t hangText="redirect_uris">
	    <vspace/>
	    Array of redirection URIs for use in redirect-based flows such as the
	    authorization code and implicit flows.
	    As required by Section 2 of <xref target="RFC6749">OAuth 2.0</xref>,
	    clients using flows with redirection MUST register their redirection URI values.
	    Authorization servers MUST implement support for this metadata value.
	  </t>

          <t hangText="token_endpoint_auth_method">
	    <vspace/>
	    The requested
          authentication method for the token endpoint. Values defined by this
          specification are: <list style="symbols">
              <t><spanx style="verb">none</spanx>: The client 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 OAuth 2.0 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>
            </list> Additional values can be defined via the IANA OAuth Token
          Endpoint Authentication Methods Registry established in <xref
          target="TEAMRegistry"/>. Absolute URIs can also be used as values
          for this parameter without being registered. 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="grant_types">
	    <vspace/>
	    Array of OAuth 2.0 grant types that the
	    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 OAuth 2.0 Section 4.1</t>

              <t><spanx style="verb">implicit</spanx>: The Implicit Grant
              described in OAuth 2.0 Section 4.2</t>

              <t><spanx style="verb">password</spanx>: The Resource Owner
              Password Credentials Grant described in OAuth 2.0 Section
              4.3</t>

              <t><spanx style="verb">client_credentials</spanx>: The Client
              Credentials Grant described in OAuth 2.0 Section 4.4</t>

              <t><spanx style="verb">refresh_token</spanx>: The Refresh Token
              Grant described in OAuth 2.0 Section 6.</t>

              <t><spanx style="verb">urn:ietf:params:oauth:grant-type:jwt-bearer</spanx>:
              The JWT Bearer Grant defined in <xref target="OAuth.JWT">OAuth
              JWT Bearer Token Profiles</xref>.</t>

              <t><spanx style="verb">urn:ietf:params:oauth:grant-type:saml2-bearer</spanx>:
              The SAML 2 Bearer Grant defined in <xref
              target="OAuth.SAML2">OAuth SAML 2 Bearer Token
              Profiles</xref>.</t>
            </list> Authorization Servers MAY allow for other values as
          defined in grant type extensions to OAuth 2.0. The extension process
          is described in OAuth 2.0 Section 2.5. If the token endpoint is used
          in the grant type, the value of this parameter MUST be the same as
          the value of the <spanx style="verb">grant_type</spanx> parameter
          passed to the token endpoint defined in the extension.
	  If omitted, the default is that the client will use only the
	  <spanx style="verb">authorization_code</spanx> Grant Type.
	  </t>

	  <t hangText="application_type">
	    <vspace/>
	    OPTIONAL.
	    Kind of the application.
	    The default, if omitted, is 
	    <spanx style="verb">web</spanx>.  The defined values are
	    <spanx style="verb">native</spanx>
	    or <spanx style="verb">web</spanx>.
	  </t>

          <t hangText="response_types">
	    <vspace/>
	    Array of the OAuth 2.0 response types
          that the client may use. These response types are defined as
          follows: <list style="symbols">
              <t><spanx style="verb">code</spanx>: The Authorization Code
              response described in OAuth 2.0 Section 4.1.</t>

              <t><spanx style="verb">token</spanx>: The Implicit response
              described in OAuth 2.0 Section 4.2.</t>
            </list> Authorization servers MAY allow for other values as
          defined in response type extensions to OAuth 2.0. The extension
          process is described in OAuth 2.0 Section 2.5. If the authorization
          endpoint is used by the grant type, the value of this parameter MUST
          be the same as the value of the <spanx style="verb">response_type</spanx>
          parameter passed to the authorization endpoint defined in the
          extension.
	  If omitted, the default is that the client will use only the
	  <spanx style="verb">code</spanx> response type.
	  </t>

          <t hangText="client_name">
	    <vspace/>
	    Human-readable name of the client to be
          presented to the user during authorization. If omitted, the
          authorization server MAY display the raw <spanx style="verb">client_id</spanx>
          value to the user instead. It is RECOMMENDED that clients always
          send this field. The value of this field MAY be internationalized,
          as described in <xref target="HumanReadableClientMetadata"/>.</t>

          <t hangText="client_uri">
	    <vspace/>
	    URL of a Web page providing information
          about the client. If present, the server SHOULD display this URL to
          the end user in a clickable fashion. It is RECOMMENDED that clients
          always send this field. The value of this field MUST point to a
          valid web page. The value of this field MAY be internationalized, as
          described in <xref target="HumanReadableClientMetadata"/>.</t>

          <t hangText="logo_uri">
	    <vspace/>
	    URL that references a logo for the client. If
          present, the server SHOULD display this image to the end user during
          approval. The value of this field MUST point to a valid image file.
          The value of this field MAY be internationalized, as described in
          <xref target="HumanReadableClientMetadata"/>.</t>

          <t hangText="scope">
	    <vspace/>
	    Space separated list of scope values (as
          described in Section 3.3 of <xref target="RFC6749">OAuth 2.0</xref>)
          that the client can use when requesting access tokens. The semantics
          of values in this list is service specific. If omitted, an
          authorization server MAY register a client with a default set of
          scopes.</t>

          <t hangText="contacts">
	    <vspace/>
	    Array of strings representing ways to contact
          people responsible for this client, typically email addresses. The
          authorization server MAY make these addresses available to end users
          for support requests for the client.</t>

          <t hangText="tos_uri">
	    <vspace/>
	    URL that points to a human-readable Terms of
          Service document for the client. The authorization server SHOULD
          display this URL to the end-user if it is given. The Terms of
          Service usually describe a contractual relationship between the
          end-user and the client that the end-user accepts when authorizing
          the client. The value of this field MUST point to a valid web page.
          The value of this field MAY be internationalized, as described in
          <xref target="HumanReadableClientMetadata"/>.</t>

          <t hangText="policy_uri">
	    <vspace/>
	    URL that points to a human-readable Policy
          document for the client. The authorization server SHOULD display
          this URL to the end-user if it is given. The policy usually
          describes how an end-user's data will be used by the client. The
          value of this field MUST point to a valid web page. The value of
          this field MAY be internationalized, as described in <xref
          target="HumanReadableClientMetadata"/>.</t>

          <t hangText="jwks_uri">
	    <vspace/>
	    URL of the client's JSON Web Key Set
	  <xref target="JWK"/> document containing the client's public keys.
          The value of this field MUST point to a valid JWK Set document.
	  These keys can be used by higher level protocols that use
	  signing or encryption.
	  </t>

          <t hangText="jwks">
	    <vspace/>
	    JSON Web Key Set <xref target="JWK"/> value
	  containing the client's public keys. The value
          of this field MUST be a JSON object containing a valid JWK Set.
          These keys can be used by higher level protocols that use
          signing or encryption.
	  This parameter is intended to be used by clients that
	  cannot use the <spanx style="verb">jwks_uri</spanx> parameter.
	  For instance, a native application might not have a location
	  to host the contents of the JWK Set that would be reachable by
	  the authorization server.
	  The <spanx style="verb">jwks_uri</spanx> and <spanx style="verb">jwks</spanx>
	  parameters MUST NOT be used together.
	  </t>

          <t hangText="software_id">
	    <vspace/>
	    Identifier for the software that comprises
          a client. Unlike <spanx style="verb">client_id</spanx>, which is
          issued by the authorization server and may vary between
          instances, the <spanx style="verb">software_id</spanx> is asserted
          by the client software on behalf of the software developer
	  and is intended to be shared among all
          instances of the client software. The identifier SHOULD NOT change when
          software version changes or when a new installation occurs.</t>

          <t hangText="software_version">
	    <vspace/>
	    Version identifier for the software
          that comprises a client. The value of this field is a string that is
          intended to be compared using string equality matching. The value of
          the <spanx style="verb">software_version</spanx> SHOULD change on
          any update to the client software.</t>
        </list></t>

      <t>Extensions and profiles of this specification MAY expand this list.
      The
      authorization server MUST ignore any client metadata values sent by the
      client that it does not understand.</t>

      <t>Client metadata values can either be communicated directly in the
      body of a registration request, as described in <xref
      target="RegistrationRequest"/>, or included as claims in a software
      statement, as described in <xref target="SoftwareStatement"/>, or a
      mixture of both. If the same client metadata name is present in both
      locations and the software statement is trusted by the authorization
      server, the value of a claim in the software statement MUST take
      precedence.</t>

      <section anchor="GrantTypesAndResponseTypes"
               title="Relationship between Grant Types and Response Types">
        <t>The <spanx style="verb">grant_types</spanx> and <spanx
        style="verb">response_types</spanx> values described above are
        partially orthogonal, as they refer to arguments passed to different
        endpoints in the OAuth protocol. However, they are related in that the
        <spanx style="verb">grant_types</spanx> available to a client
        influence the <spanx style="verb">response_types</spanx> that the
        client is allowed to use, and vice versa. For instance, a <spanx
        style="verb">grant_types</spanx> value that includes <spanx
        style="verb">authorization_code</spanx> implies a <spanx style="verb">response_types</spanx>
        value that includes <spanx style="verb">code</spanx>, as both values
        are defined as part of the OAuth 2.0 authorization code grant. As
        such, a server supporting these fields SHOULD take steps to ensure
        that a client cannot register itself into an inconsistent state, for
        example by returning an <spanx style="verb">invalid_client_metadata</spanx>
        error response to an inconsistent registration request.</t>

        <t>The correlation between the two fields is listed in the table
        below.</t>

        <texttable>
          <ttcol>grant_types value includes:</ttcol>

          <ttcol>response_types value includes:</ttcol>

          <c>authorization_code</c>

          <c>code</c>

          <c>implicit</c>

          <c>token</c>

          <c>password</c>

          <c>(none)</c>

          <c>client_credentials</c>

          <c>(none)</c>

          <c>refresh_token</c>

          <c>(none)</c>

          <c>urn:ietf:params:oauth:grant-type:jwt-bearer</c>

          <c>(none)</c>

          <c>urn:ietf:params:oauth:grant-type:saml2-bearer</c>

          <c>(none)</c>
        </texttable>

        <t>Extensions and profiles of this document that introduce new values
        to either the <spanx style="verb">grant_types</spanx> or <spanx
        style="verb">response_types</spanx> parameter MUST document all
        correspondences between these two parameter types.</t>
      </section>

      <section anchor="HumanReadableClientMetadata"
               title="Human Readable Client Metadata">
        <t>Human-readable client metadata values and client metadata values
        that reference human-readable values MAY be represented in multiple
        languages and scripts. For example, the values of fields such as
        <spanx style="verb">client_name</spanx>, <spanx style="verb">tos_uri</spanx>,
        <spanx style="verb">policy_uri</spanx>, <spanx style="verb">logo_uri</spanx>,
        and <spanx style="verb">client_uri</spanx> might have multiple
        locale-specific values in some client registrations to facilitate use
        in different locations.</t>

        <t>To specify the languages and scripts, <xref
        target="RFC5646">BCP47</xref> language tags are added to client
        metadata member names, delimited by a # character. Since <xref
        target="RFC7159">JSON</xref> member names are case sensitive, it is
        RECOMMENDED that language tag values used in Claim Names be spelled
        using the character case with which they are registered in the <xref
        target="IANA.Language">IANA Language Subtag Registry</xref>. In
        particular, normally language names are spelled with lowercase
        characters, region names are spelled with uppercase characters, and
        languages are spelled with mixed case characters. However, since BCP47
        language tag values are case insensitive, implementations SHOULD
        interpret the language tag values supplied in a case insensitive
        manner. Per the recommendations in BCP47, language tag values used in
        metadata member names should only be as specific as necessary. For
        instance, using <spanx style="verb">fr</spanx> might be sufficient in
        many contexts, rather than <spanx style="verb">fr-CA</spanx> or <spanx
        style="verb">fr-FR</spanx>.</t>

        <t>For example, a client could represent its name in English as <spanx
        style="verb">"client_name#en": "My Client"</spanx> and its name in
        Japanese as <spanx style="verb">"client_name#ja-Jpan-JP": "\u30AF\u30E9\u30A4\u30A2\u30F3\u30C8\u540D"</spanx>
        within the same registration request. The authorization server MAY
        display any or all of these names to the resource owner during the
        authorization step, choosing which name to display based on system
        configuration, user preferences or other factors.</t>

        <t>If any human-readable field is sent without a language tag, parties
        using it MUST NOT make any assumptions about the language, character
        set, or script of the string value, and the string value MUST be used
        as-is wherever it is presented in a user interface. To facilitate
        interoperability, it is RECOMMENDED that clients and servers use a
        human-readable field without any language tags in addition to any
        language-specific fields, and it is RECOMMENDED that any
        human-readable fields sent without language tags contain values
        suitable for display on a wide variety of systems.</t>

        <t>Implementer's Note: Many JSON libraries make it possible to
        reference members of a JSON object as members of an object construct
        in the native programming environment of the library. However, while
        the <spanx style="verb">#</spanx> character is a valid character
        inside of a JSON object's member names, it is not a valid character
        for use in an object member name in many programming environments.
        Therefore, implementations will need to use alternative access forms
        for these claims. For instance, in JavaScript, if one parses the JSON
        as follows, <spanx style="verb">var j = JSON.parse(json);</spanx>,
        then the member <spanx style="verb">client_name#en-us</spanx> can be
        accessed using the JavaScript syntax <spanx style="verb">j["client_name#en-us"]</spanx>.</t>
      </section>

      <section anchor="SoftwareStatement" title="Software Statement">
        <t>A software statement is a JSON Web Token (JWT) <xref target="JWT"/>
        that asserts metadata values about the client software as a bundle.
	A set of claims that can be used in a software statement are defined
        <xref target="ClientMetadata"/>.
	When presented to the
        authorization server as part of a client registration request,
        the software statement MUST be digitally signed or MACed using <xref
        target="JWS">JWS</xref> and MUST contain an <spanx style="verb">iss</spanx>
        (issuer) claim denoting the party attesting to the claims in the
        software statement. It is RECOMMENDED that software statements be
        digitally signed using the <spanx style="verb">RS256</spanx> signature algorithm,
	although particular applications MAY specify the use of different algorithms.</t>

        <t>The means by which a client or developer obtains a software
        statement are outside the scope of this specification. Some common
        methods could include a client developer generating a client-specific
        JWT registering with a software API publisher to obtain a software
        statement for a class of clients. The software statement is typically
        distributed with all instances of a client application.</t>

        <t>The criteria by which authorization servers determine whether to
        trust and utilize the information in a software statement are beyond
        the scope of this specification.</t>

        <t>In some cases, authorization servers MAY choose to accept a
        software statement value directly as a client identifier in an authorization
        request, without a prior dynamic client registration having been
        performed. The circumstances under which an authorization server would
        do so, and the specific software statement characteristics required in
        this case, are beyond the scope of this specification.</t>
      </section>
    </section>

    <section anchor="RegistrationEndpoint"
             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 be registered with
      the authorization server. The client registration endpoint MUST accept
      HTTP POST messages with request parameters encoded in the entity body
      using the <spanx style="verb">application/json</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 client registration endpoint MAY be an OAuth 2.0 protected
      resource and accept an initial access token in the form of an <xref
      target="RFC6749">OAuth 2.0</xref> access token to limit registration to
      only previously authorized parties. The method by which the initial
      access token is obtained by the client or developer is generally
      out-of-band and is out of scope for this specification. The method by
      which the initial access token is verified and validated by the client
      registration endpoint is out of scope for this specification.</t>

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

      <section anchor="RegistrationRequest"
               title="Client Registration Request">
        <t>This operation registers a client with the authorization server.
        The authorization server assigns this client a unique client
        identifier, optionally assigns a client secret, and associates the
        metadata given in the request with the issued client identifier. The
        request includes any client metadata parameters being specified for
        the client during the registration. The authorization server MAY
        provision default values for any items omitted in the client
        metadata.</t>

        <t>To register, the client or developer sends an HTTP POST to the
        client registration endpoint with a content type of <spanx
        style="verb">application/json</spanx>. The HTTP Entity Payload is a
        <xref target="RFC7159">JSON</xref> document consisting of a JSON
        object and all requested client metadata values as top-level members
        of that JSON object.</t>

        <t>Client metadata values may also be provided in a software
        statement, as described in <xref target="SoftwareStatement"/>.
        Software statements are included in the requesting JSON object using this
        member: <list style="hanging">
            <t hangText="software_statement">
	      <vspace/>
	      A software statement containing
            client metadata values about the client software as claims.</t>
          </list></t>

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

        <figure>
          <preamble>The following is a non-normative example request not using
          an initial access token
	  (with line wraps within values for display purposes only):</preamble>

          <artwork><![CDATA[
  POST /register HTTP/1.1
  Content-Type: application/json
  Accept: application/json
  Host: server.example.com

  {
   "redirect_uris":[
     "https://client.example.org/callback",
     "https://client.example.org/callback2"],
   "client_name":"My Example Client",
   "client_name#ja-Jpan-JP":
      "\u30AF\u30E9\u30A4\u30A2\u30F3\u30C8\u540D",
   "token_endpoint_auth_method":"client_secret_basic",
   "logo_uri":"https://client.example.org/logo.png",
   "jwks_uri":"https://client.example.org/my_public_keys.jwks",
   "example_extension_parameter": "example_value"
  }
]]></artwork>
        </figure>

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

        <figure>
          <preamble>The following is a non-normative example request using an
          initial access token
	  (with line wraps within values for display purposes only):</preamble>

          <artwork><![CDATA[
  POST /register HTTP/1.1
  Content-Type: application/json
  Accept: application/json
  Authorization: Bearer ey23f2.adfj230.af32-developer321
  Host: server.example.com

  {
   "redirect_uris":["https://client.example.org/callback",
      "https://client.example.org/callback2"],
   "client_name":"My Example Client",
   "client_name#ja-Jpan-JP":
      "\u30AF\u30E9\u30A4\u30A2\u30F3\u30C8\u540D",
   "token_endpoint_auth_method":"client_secret_basic",
   "policy_uri":"https://client.example.org/policy.html",
   "jwks":{"keys":[{...omitted for brevity...}]},
   "example_extension_parameter": "example_value"
  }
]]></artwork>
        </figure>

        <figure>
          <preamble>In the following example, some registration parameters are
          conveyed as claims in a software statement, while some values
          specific to the client instance are conveyed as regular parameters
          (with line wraps within values for display purposes only):</preamble>

          <artwork><![CDATA[
  POST /register HTTP/1.1
  Content-Type: application/json
  Accept: application/json
  Host: server.example.com

  {
    "redirect_uris":[
      "https://client.example.org/callback",
      "https://client.example.org/callback2"
    ],
    "software_statement":"eyJhbGciOiJFUzI1NiJ9.
       eyJpc3Mi[...omitted for brevity...].
       J9l-ZhwP[...omitted for brevity...]",
    "scope":"read write",
    "example_extension_parameter":"example_value"
  }
]]></artwork>
        </figure>
      </section>

      <section anchor="RegistrationResponse"
               title="Client Registration Response">
        <t>Upon successful registration, the authorization server returns a
        client identifier for the client. The server responds with an HTTP 201
        Created code and a body of type <spanx style="verb">application/json</spanx>
        with content as described in <xref target="ClientInfoResponse"/>.</t>

        <t>Upon an unsuccessful registration, the authorization server
        responds with an error, as described in <xref
        target="ClientRegistrationError"/>.</t>
      </section>
    </section>

    <section anchor="Responses" title="Responses">
      <t>The following responses are sent in response to registration
      requests.</t>

      <section anchor="ClientInfoResponse" title="Client Information Response">
        <t>The response contains the client identifier as well as the client
        secret, if the client is a confidential client. The response MAY
        contain additional fields as specified by extensions to this
        specification.</t>

        <t><list style="hanging">
            <t hangText="client_id">
	      <vspace/>
	      REQUIRED. OAuth 2.0 client identifier. It
            SHOULD NOT be currently valid for any other registered client,
            though an authorization server MAY issue the same client
            identifier to multiple instances of a registered client,
	    at its discretion.</t>

            <t hangText="client_secret">
	      <vspace/>
	      OPTIONAL. OAuth 2.0 client secret. If
            issued, 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 <xref target="RFC6749">OAuth
            2.0</xref> Section 2.3.1.</t>

            <t hangText="client_id_issued_at">
	      <vspace/>
	      OPTIONAL. Time at which the
            client identifier was issued. The time is represented as the
            number of seconds from 1970-01-01T0:0:0Z as measured in UTC until
            the date/time.</t>

            <t hangText="client_secret_expires_at">
	      <vspace/>
	      REQUIRED if <spanx style="verb">client_secret</spanx> is issued.
	      Time at which the
            client secret will expire or 0 if it
            will not expire. The time is represented as the number of seconds
            from 1970-01-01T0:0:0Z as measured in UTC until the date/time.</t>
          </list></t>

        <t>Additionally, the authorization server MUST return all registered
        metadata about this client, including any fields provisioned by the
        authorization server itself. The authorization server MAY reject or
        replace any of the client's requested metadata values submitted during
        the registration or update requests and substitute them with suitable
        values.</t>

        <t>The response is an <spanx style="verb">application/json</spanx>
        document with all parameters as top-level members of a <xref
        target="RFC7159">JSON object</xref>.</t>

        <t>If a software statement was used as part of the registration, its
        value MUST be returned in the response along with other metadata.
        Client metadata elements used from the software statement MUST also be
        returned directly as top-level client metadata values in the
        registration response (possibly with different values, since the
        values requested and the values used may differ).</t>

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

          <artwork><![CDATA[
  HTTP/1.1 201 Created
  Content-Type: application/json
  Cache-Control: no-store
  Pragma: no-cache

  {
   "client_id":"s6BhdRkqt3",
   "client_secret": "cf136dc3c1fc93f31185e5885805d",
   "client_id_issued_at":2893256800,
   "client_secret_expires_at":2893276800,
   "redirect_uris":[
     "https://client.example.org/callback",
     "https://client.example.org/callback2"],
   "grant_types": ["authorization_code", "refresh_token"],
   "client_name":"My Example Client",
   "client_name#ja-Jpan-JP":
      "\u30AF\u30E9\u30A4\u30A2\u30F3\u30C8\u540D",
   "token_endpoint_auth_method":"client_secret_basic",
   "logo_uri":"https://client.example.org/logo.png",
   "jwks_uri":"https://client.example.org/my_public_keys.jwks",
   "example_extension_parameter": "example_value"
  }
]]></artwork>
        </figure>
      </section>

      <section anchor="ClientRegistrationError"
               title="Client Registration Error Response">
        <t>When an OAuth 2.0 error condition occurs, such as the client
        presenting an invalid initial access token, the authorization server
        returns an error response appropriate to the OAuth 2.0 token type.</t>

        <t>When a registration error condition occurs, the authorization
        server returns an HTTP 400 status code (unless otherwise specified)
        with content type <spanx style="verb">application/json</spanx>
        consisting of a <xref target="RFC7159">JSON object</xref> describing
        the error in the response body.</t>

        <t>
	  Two members are defined for inclusion in the JSON object:
	</t>
        <t>
	  <list style="hanging">
            <t hangText="error">
	      <vspace/>
	      REQUIRED.  Single ASCII error code string.</t>

            <t hangText="error_description">
	      <vspace/>
	      OPTIONAL.  Human-readable ASCII text
            description of the error used for debugging.</t>
          </list>
	  Other members MAY also be included, and if not understood, MUST be ignored.
	</t>

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

        <t><list style="hanging">
            <t hangText="invalid_redirect_uri">
	      <vspace/>
	      The value of one or more redirection URIs is invalid.</t>

            <t hangText="invalid_client_metadata">
	      <vspace/>
	      The value of one of the
            client metadata 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>

            <t hangText="invalid_software_statement">
	      <vspace/>
	      The software statement
            presented is invalid.</t>

            <t hangText="unapproved_software_statement">
	      <vspace/>
	      The software statement
            presented is not approved for use by this authorization
            server.</t>
          </list></t>

        <figure>
          <preamble>Following is a non-normative example of an error response
          resulting from a redirection URI that has been blacklisted by the
          authorization server
	  (with line wraps within values for display purposes only):</preamble>

          <artwork><![CDATA[
  HTTP/1.1 400 Bad Request
  Content-Type: application/json
  Cache-Control: no-store
  Pragma: no-cache

  {
   "error": "invalid_redirect_uri",
   "error_description": "The redirection URI
     http://sketchy.example.com is not allowed by this server."
  }
]]></artwork>
        </figure>

        <figure>
          <preamble>Following is a non-normative example of an error response
          resulting from an inconsistent combination of <spanx style="verb">response_types</spanx>
          and <spanx style="verb">grant_types</spanx> values
	  (with line wraps within values for display purposes only):</preamble>

          <artwork><![CDATA[
  HTTP/1.1 400 Bad Request
  Content-Type: application/json
  Cache-Control: no-store
  Pragma: no-cache

  {
   "error": "invalid_client_metadata",
   "error_description": "The grant type 'authorization_code' must be
     registered along with the response type 'code' but found only 
    'implicit' instead."
  }
]]></artwork>
        </figure>
      </section>
    </section>

    <section anchor="IANA" title="IANA Considerations">
      <section anchor="MetadataRegistry"
               title="OAuth Dynamic Registration Client Metadata Registry">
        <t>This specification establishes the OAuth Dynamic Registration Client
        Metadata registry.</t>

        <t>OAuth registration client metadata values are registered with a
        Specification Required (<xref target="RFC5226"/>) after a two-week
        review period on the oauth-ext-review@ietf.org mailing list, on the
        advice of one or more Designated Experts. However, to allow for the
        allocation of values prior to publication, the Designated Expert(s)
        may approve registration once they are satisfied that such a
        specification will be published.</t>

        <t>Registration requests must be sent to the oauth-ext-review@ietf.org
        mailing list for review and comment, with an appropriate subject
        (e.g., "Request to register OAuth Dynamic Registration Client Metadata name:
        example").</t>

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

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

        <section anchor="MetadataTemplate" title="Registration Template">
          <t><list style="hanging">
              <t hangText="Client Metadata Name:">
		<vspace/>
		The name requested (e.g.,
              "example"). This name is case sensitive. Names that match other
              registered names in a case insensitive manner SHOULD NOT be
              accepted.</t>

              <t hangText="Client Metadata Description:">
		<vspace/>
		Brief
              description of the metadata value (e.g., "Example
              description").</t>

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

              <t hangText="Specification document(s):">
		<vspace/>
		Reference to the
              document(s) that specify the token endpoint authorization
              method, preferably including a URI that can be used to retrieve
              a copy of the document(s). An indication of the relevant
              sections may also be included but is not required.</t>
            </list></t>
        </section>

        <section anchor="MetadataContents" title="Initial Registry Contents">
          <t>The initial contents of the OAuth Dynamic Registration Client Metadata
          registry are:</t>

          <t><?rfc subcompact="yes"?> <list style="symbols">
              <t>Client Metadata Name: <spanx style="verb">redirect_uris</spanx></t>

              <t>Client Metadata Description: Array of redirection URIs for use
              in redirect-based flows</t>

              <t>Change controller: IESG</t>

              <t>Specification document(s): [[ this document ]]</t>
            </list></t>

          <t><list style="symbols">
              <t>Client Metadata Name: <spanx style="verb">token_endpoint_auth_method</spanx></t>

              <t>Client Metadata Description: Requested authentication method
              for the token endpoint</t>

              <t>Change controller: IESG</t>

              <t>Specification document(s): [[ this document ]]</t>
            </list></t>

          <t><list style="symbols">
              <t>Client Metadata Name: <spanx style="verb">grant_types</spanx></t>

              <t>Client Metadata Description: Array of OAuth 2.0 grant types
              that the client may use</t>

              <t>Change controller: IESG</t>

              <t>Specification document(s): [[ this document ]]</t>
            </list></t>

          <t><list style="symbols">
              <t>Client Metadata Name: <spanx style="verb">response_types</spanx></t>

              <t>Client Metadata Description: Array of the OAuth 2.0 response
              types that the client may use</t>

              <t>Change controller: IESG</t>

              <t>Specification document(s): [[ this document ]]</t>
            </list></t>

          <t><list style="symbols">
              <t>Client Metadata Name: <spanx style="verb">client_name</spanx></t>

              <t>Client Metadata Description: Human-readable name of the
              client to be presented to the user</t>

              <t>Change Controller: IESG</t>

              <t>Specification Document(s): [[ this document ]]</t>
            </list></t>

          <t><list style="symbols">
              <t>Client Metadata Name: <spanx style="verb">client_uri</spanx></t>

              <t>Client Metadata Description: URL of a Web page providing
              information about the client</t>

              <t>Change Controller: IESG</t>

              <t>Specification Document(s): [[ this document ]]</t>
            </list></t>

          <t><list style="symbols">
              <t>Client Metadata Name: <spanx style="verb">logo_uri</spanx></t>

              <t>Client Metadata Description: URL that references a logo for
              the client</t>

              <t>Change Controller: IESG</t>

              <t>Specification Document(s): [[ this document ]]</t>
            </list></t>

          <t><list style="symbols">
              <t>Client Metadata Name: <spanx style="verb">scope</spanx></t>

              <t>Client Metadata Description: Space separated list of scope
              values</t>

              <t>Change Controller: IESG</t>

              <t>Specification Document(s): [[ this document ]]</t>
            </list></t>

          <t><list style="symbols">
              <t>Client Metadata Name: <spanx style="verb">contacts</spanx></t>

              <t>Client Metadata Description: Array of strings representing ways to contact
	      people responsible for this client, typically email addresses</t>

              <t>Change Controller: IESG</t>

              <t>Specification document(s): [[ this document ]]</t>
            </list></t>

          <t><list style="symbols">
              <t>Client Metadata Name: <spanx style="verb">tos_uri</spanx></t>

              <t>Client Metadata Description: URL that points to a
              human-readable Terms of Service document for the client</t>

              <t>Change Controller: IESG</t>

              <t>Specification Document(s): [[ this document ]]</t>
            </list></t>

          <t><list style="symbols">
              <t>Client Metadata Name: <spanx style="verb">policy_uri</spanx></t>

              <t>Client Metadata Description: URL that points to a
              human-readable Policy document for the client</t>

              <t>Change Controller: IESG</t>

              <t>Specification Document(s): [[ this document ]]</t>
            </list></t>

          <t><list style="symbols">
              <t>Client Metadata Name: <spanx style="verb">jwks_uri</spanx></t>

              <t>Client Metadata Description: URL for the client's <xref
              target="JWK">JSON Web Key Set</xref> document representing the
              client's public keys</t>

              <t>Change Controller: IESG</t>

              <t>Specification Document(s): [[ this document ]]</t>
            </list><list style="symbols">
              <t>Client Metadata Name: <spanx style="verb">jwks</spanx></t>

              <t>Client Metadata Description: The client's <xref
              target="JWK">JSON Web Key Set</xref> document representing the
              client's public keys</t>

              <t>Change Controller: IESG</t>

              <t>Specification Document(s): [[ this document ]]</t>
            </list></t>

          <t><list style="symbols">
              <t>Client Metadata Name: <spanx style="verb">software_id</spanx></t>

              <t>Client Metadata Description: Identifier for the software that
              comprises a client</t>

              <t>Change Controller: IESG</t>

              <t>Specification Document(s): [[ this document ]]</t>
            </list></t>

          <t><list style="symbols">
              <t>Client Metadata Name: <spanx style="verb">software_version</spanx></t>

              <t>Client Metadata Description: Version identifier for the
              software that comprises a client</t>

              <t>Change Controller: IESG</t>

              <t>Specification Document(s): [[ this document ]]</t>
            </list></t>

          <t><list style="symbols">
              <t>Client Metadata Name: <spanx style="verb">client_id</spanx></t>

              <t>Client Metadata Description: Client identifier</t>

              <t>Change Controller: IESG</t>

              <t>Specification Document(s): [[ this document ]]</t>
            </list></t>

          <t><list style="symbols">
              <t>Client Metadata Name: <spanx style="verb">client_secret</spanx></t>

              <t>Client Metadata Description: Client secret</t>

              <t>Change Controller: IESG</t>

              <t>Specification Document(s): [[ this document ]]</t>
            </list></t>

          <t><list style="symbols">
              <t>Client Metadata Name: <spanx style="verb">client_id_issued_at</spanx></t>

              <t>Client Metadata Description: Time at which the
	      client identifier was issued</t>

              <t>Change Controller: IESG</t>

              <t>Specification Document(s): [[ this document ]]</t>
            </list></t>

          <t><list style="symbols">
              <t>Client Metadata Name: <spanx style="verb">client_secret_expires_at</spanx></t>

              <t>Client Metadata Description: Time at which the
	      client secret will expire</t>

              <t>Change Controller: IESG</t>

              <t>Specification Document(s): [[ this document ]]</t>
            </list></t>
        </section>

        <?rfc subcompact="no"?>
      </section>

      <section anchor="TEAMRegistry"
               title="OAuth Token Endpoint Authentication Methods Registry">
        <t>This specification establishes the OAuth Token Endpoint
        Authentication Methods registry.</t>

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

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

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

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

        <section anchor="TEAMTemplate" title="Registration Template">
          <t><list style="hanging">
              <t hangText="Token Endpoint Authorization Method Name:">
		<vspace/>
		The name
              requested (e.g., "example"). This name is case sensitive. Names
              that match other registered names in a case insensitive manner
              SHOULD NOT be accepted.</t>

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

              <t hangText="Specification document(s):">
		<vspace/>
		Reference to the
              document(s) that specify the token endpoint authorization
              method, preferably including a URI that can be used to retrieve
              a copy of the document(s). An indication of the relevant
              sections may also be included but is not required.</t>
            </list></t>
        </section>

        <section anchor="TEAMContents" title="Initial Registry Contents">
          <t>The initial contents of the OAuth Token Endpoint Authentication
          Methods registry are:</t>

          <t><?rfc subcompact="yes"?> <list style="symbols">
              <t>Token Endpoint Authorization Method Name: <spanx
              style="verb">none</spanx></t>

              <t>Change controller: IESG</t>

              <t>Specification document(s): [[ this document ]]</t>
            </list></t>

          <t><list style="symbols">
              <t>Token Endpoint Authorization Method Name: <spanx
              style="verb">client_secret_post</spanx></t>

              <t>Change controller: IESG</t>

              <t>Specification document(s): [[ this document ]]</t>
            </list></t>

          <t><list style="symbols">
              <t>Token Endpoint Authorization Method Name: <spanx
              style="verb">client_secret_basic</spanx></t>

              <t>Change controller: IESG</t>

              <t>Specification document(s): [[ this document ]]</t>
            </list></t>
        </section>

        <?rfc subcompact="no"?>
      </section>
    </section>

    <section anchor="Security" title="Security Considerations">
      <t>Since requests to the client registration endpoint result in the
      transmission of clear-text credentials (in the HTTP request and
      response), the authorization server MUST require the use of a
      transport-layer security mechanism when sending requests to the
      registration endpoint. The server MUST support TLS 1.2 <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>For clients that use redirect-based grant types such as <spanx
      style="verb">authorization_code</spanx> and <spanx style="verb">implicit</spanx>,
      authorization servers MUST require clients to register their <spanx
      style="verb">redirect_uri</spanx> values.  This
      can help mitigate attacks where rogue actors inject and impersonate a
      validly registered client and intercept its authorization code or tokens
      through an invalid redirection URI or open redirector.</t>

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

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

      <t>Unless used as a claim in a software statement, the
      authorization server MUST treat all client metadata as self-asserted.
      For instance, a rogue client might use the name and logo of a
      legitimate client that it is trying to impersonate. Additionally, a
      rogue client might try to use the software identifier or software
      version of a legitimate client to attempt to associate itself on the
      authorization server with instances of the legitimate client. To counteract
      this, an authorization server needs to take steps to mitigate this
      risk by looking at the entire registration request and client
      configuration. For instance, an authorization server could issue a warning if the
      domain/site of the logo doesn't match the domain/site of redirection URIs.
      An authorization server could also refuse registration requests from a known
      software identifier that is requesting different redirection URIs or a
      different client homepage URI. An authorization server can also present
      warning messages to end users about dynamically registered clients in
      all cases, especially if such clients have been recently registered or
      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_uri</spanx>, <spanx style="verb">tos_uri</spanx>,
      <spanx style="verb">client_uri</spanx>, and <spanx style="verb">policy_uri</spanx>).
      For instance, a rogue client could specify a registration request with a
      reference to a drive-by download in the <spanx style="verb">policy_uri</spanx>.
      The authorization server SHOULD check to see if the <spanx style="verb">logo_uri</spanx>,
      <spanx style="verb">tos_uri</spanx>, <spanx style="verb">client_uri</spanx>,
      and <spanx style="verb">policy_uri</spanx> have the same host and scheme
      as the those defined in the array of <spanx style="verb">redirect_uris</spanx>
      and that all of these URIs resolve to valid web pages.</t>

      <t>Clients MAY use both the direct JSON object and the JWT-encoded
      software statement to present client metadata to the authorization
      server as part of the registration request. A software statement is
      cryptographically protected and represents claims made by the issuer of
      the statement, while the JSON object represents the self-asserted claims
      made by the client or developer directly. If the software statement is valid
      and trusted, the values of client metadata within the software statement
      MUST take precedence over those metadata values presented in the plain
      JSON object, which could have been modified en route.</t>

      <t>The software statement is an item that is self-asserted by the
      client, even though its contents have been digitally signed or MACed
      by the issuer of the
      software statement. As such, presentation of the software statement is
      not sufficient in most cases to fully identity a piece of client
      software. An initial access token, in contrast, does not necessarily
      contain information about a particular piece of client software but
      instead represents authorization to use the registration endpoint. An
      authorization server MUST consider the full registration request,
      including the software statement, initial access token, and JSON
      client metadata values, when deciding whether to honor a given registration
      request.</t>

      <t>
	If an authorization server receives a registration request for a client
	that uses the same <spanx style="verb">software_id</spanx> and
	<spanx style="verb">software_version</spanx> values as another client,
	the server should treat the new registration as being suspect.
	It is possible that the new client is trying to impersonate the existing client.
      </t>

      <t>Since a client identifier is a public value that can be used to
      impersonate a client at the authorization endpoint, an authorization
      server that decides to issue the same client identifier to
      multiple instances of a registered client MUST be very particular about the
      circumstances under which this occurs. For instance, the authorization
      server can limit a given client identifier to clients using the same
      redirect-based flow and the same redirection URIs. An
      authorization server SHOULD NOT issue the same client secret to
      multiple instances of a registered client,
      even if they are issued the same client identifier,
      or else the client secret
      could be leaked, allowing malicious imposters to impersonate a
      confidential client.</t>
    </section>
  </middle>

  <back>
    <references title="Normative References">

      <?rfc include='http://xml2rfc.tools.ietf.org/public/rfc/bibxml/reference.RFC.2119.xml'?>
      <?rfc include='http://xml2rfc.tools.ietf.org/public/rfc/bibxml/reference.RFC.2246.xml'?>
      <?rfc include='http://xml2rfc.tools.ietf.org/public/rfc/bibxml/reference.RFC.5226.xml'?>
      <?rfc include='http://xml2rfc.tools.ietf.org/public/rfc/bibxml/reference.RFC.5246.xml'?>
      <?rfc include='http://xml2rfc.tools.ietf.org/public/rfc/bibxml/reference.RFC.5646.xml'?>
      <?rfc include='http://xml2rfc.tools.ietf.org/public/rfc/bibxml/reference.RFC.6125.xml'?>
      <?rfc include='http://xml2rfc.tools.ietf.org/public/rfc/bibxml/reference.RFC.6749.xml'?>
      <?rfc include='http://xml2rfc.tools.ietf.org/public/rfc/bibxml/reference.RFC.6750.xml'?>
      <?rfc include='http://xml2rfc.tools.ietf.org/public/rfc/bibxml/reference.RFC.7159.xml'?>

      <reference anchor="JWT">
        <front>
          <title>JSON Web Token (JWT)</title>

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

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

              <uri>http://self-issued.info/</uri>
            </address>
          </author>

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

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

              <uri>http://www.thread-safe.com/</uri>
            </address>
          </author>

          <author fullname="Nat Sakimura" initials="N." surname="Sakimura">
            <organization abbrev="NRI">Nomura Research
            Institute</organization>

            <address>
              <email>n-sakimura@nri.co.jp</email>

              <uri>http://nat.sakimura.org/</uri>
            </address>
          </author>

          <date day="1" month="July" year="2014"/>
        </front>

        <seriesInfo name="Internet-Draft"
                    value="draft-ietf-oauth-json-web-token"/>

        <format target="http://tools.ietf.org/html/draft-ietf-oauth-json-web-token"
                type="HTML"/>
      </reference>

      <reference anchor="OAuth.JWT">
        <front>
          <title abbrev="OAuth JWT Assertion Profiles">JSON Web Token (JWT)
          Profile for OAuth 2.0 Client Authentication and Authorization
          Grants</title>

          <!-- add 'role="editor"' below for the editors if appropriate -->

          <author fullname="Michael B. Jones" initials="M.B." surname="Jones">
            <!-- role="editor" -->

            <organization>Microsoft</organization>

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

              <uri>http://self-issued.info/</uri>
            </address>
          </author>

          <author fullname="Brian Campbell" initials="B." surname="Campbell">
            <organization abbrev="Ping Identity">Ping Identity</organization>

            <address>
              <email>brian.d.campbell@gmail.com</email>
            </address>
          </author>

          <author fullname="Chuck Mortimore" initials="C." surname="Mortimore">
            <organization abbrev="Salesforce">Salesforce</organization>

            <address>
              <email>cmortimore@salesforce.com</email>
            </address>
          </author>

          <date day="28" month="April" year="2014"/>
        </front>

        <seriesInfo name="Internet-Draft" value="draft-ietf-oauth-jwt-bearer"/>

        <format target="http://tools.ietf.org/html/draft-ietf-oauth-jwt-bearer"
                type="HTML"/>
      </reference>

      <reference anchor="OAuth.SAML2">
        <front>
          <title abbrev="OAuth SAML Assertion Profiles">SAML 2.0 Profile for
          OAuth 2.0 Client Authentication and Authorization Grants</title>

          <!-- add 'role="editor"' below for the editors if appropriate -->

          <author fullname="Brian Campbell" initials="B." surname="Campbell">
            <organization abbrev="Ping Identity">Ping Identity</organization>

            <address>
              <email>brian.d.campbell@gmail.com</email>
            </address>
          </author>

          <author fullname="Chuck Mortimore" initials="C." surname="Mortimore">
            <organization abbrev="Salesforce">Salesforce.com</organization>

            <address>
              <email>cmortimore@salesforce.com</email>
            </address>
          </author>

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

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

              <uri>http://self-issued.info/</uri>
            </address>
          </author>

          <date day="28" month="April" year="2014"/>
        </front>

        <seriesInfo name="Internet-Draft"
                    value="draft-ietf-oauth-saml2-bearer"/>

        <format target="http://tools.ietf.org/html/draft-ietf-oauth-saml2-bearer"
                type="HTML"/>
      </reference>

      <reference anchor="JWS">
        <front>
          <title>JSON Web Signature (JWS)</title>

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

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

              <uri>http://self-issued.info/</uri>
            </address>
          </author>

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

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

              <uri>http://www.thread-safe.com/</uri>
            </address>
          </author>

          <author fullname="Nat Sakimura" initials="N." surname="Sakimura">
            <organization abbrev="NRI">Nomura Research
            Institute</organization>

            <address>
              <email>n-sakimura@nri.co.jp</email>

              <uri>http://nat.sakimura.org/</uri>
            </address>
          </author>

          <date day="1" month="July" year="2014"/>
        </front>

        <seriesInfo name="Internet-Draft"
                    value="draft-ietf-jose-json-web-signature"/>

        <format type="HTML"/>
      </reference>

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

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

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

              <uri>http://self-issued.info/</uri>
            </address>
          </author>

          <date day="1" month="July" year="2014"/>
        </front>

        <seriesInfo name="Internet-Draft" value="draft-ietf-jose-json-web-key"/>

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

      <reference anchor="IANA.Language">
        <front>
          <title>Language Subtag Registry</title>

          <author>
            <organization>Internet Assigned Numbers Authority
            (IANA)</organization>
          </author>

          <date year="2005"/>
        </front>

        <format target="http://www.iana.org/assignments/language-subtag-registry"
                type="TXT"/>
      </reference>
    </references>

    <references title="Informative References">

      <reference anchor="OAuth.Registration.Management">
        <front>
          <title abbrev="OAuth 2.0 Dynamic Registration Management">OAuth 2.0
          Dynamic Client Registration Management Protocol</title>

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

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

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

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

              <uri>http://self-issued.info/</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="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>

          <author fullname="Phil Hunt" initials="P" surname="Hunt">
            <organization>Oracle Corporation</organization>

            <address>
              <email>phil.hunt@yahoo.com</email>
            </address>
          </author>

          <date day="3" month="July" year="2014"/>
        </front>

        <seriesInfo name="Internet-Draft"
                    value="draft-ietf-oauth-dyn-reg-management"/>

        <format target="http://tools.ietf.org/html/draft-ietf-oauth-dyn-reg-management"
                type="HTML"/>
      </reference>

    </references>

    <section anchor="UseCases" title="Use Cases">
      <t>This appendix describes different ways that this specification can be
      utilized, including describing some of the choices that may need to be
      made. Some of the choices are independent and can be used in
      combination, whereas some of the choices are interrelated.</t>

      <section anchor="OpenOrProtected"
               title="Open versus Protected Dynamic Client Registration">
        <section anchor="OpenRegistration"
                 title="Open Dynamic Client Registration">
          <t>Authorization servers that support open registration allow
          registrations to be made with no initial access token. This allows
          all client software to register with the authorization server.</t>
        </section>

        <section anchor="ProtectedRegistration"
                 title="Protected Dynamic Client Registration">
          <t>Authorization servers that support protected registration require
          that an initial access token be used when making registration
          requests. While the method by which a client or developer receives
          this initial access token and the method by which the authorization
          server validates this initial access token are out of scope for this
          specification, a common approach is for the developer to use a
          manual pre-registration portal at the authorization server that
          issues an initial access token to the developer.</t>
        </section>
      </section>

      <section anchor="SoftwareStatementUses"
               title="Registration Without or With Software Statements">
        <section anchor="NoSoftwareStatement"
                 title="Registration Without a Software Statement">
          <t>When a software statement is not used in the registration
          request, the authorization server must be willing to use client
          metadata values without them being digitally signed or MACed (and thereby
          attested to) by any authority. (Note that this choice is independent
          of the Open versus Protected choice, and that an initial access
          token is another possible form of attestation.)</t>
        </section>

        <section anchor="WithSoftwareStatement"
                 title="Registration With a Software Statement">
          <t>A software statement can be used in a registration request to
          provide attestation by an authority for a set of client metadata values.
	  This can be useful when the
          authorization server wants to restrict registration to client
          software attested to by a set of authorities or when it wants to
          know that multiple registration requests refer to the same piece of
          client software.</t>
        </section>
      </section>

      <section anchor="ByClientOrDeveloper"
               title="Registration by the Client or Developer">
        <section anchor="ByClient" title="Registration by the Client">
          <t>In some use cases, client software will dynamically register
          itself with an authorization server to obtain a client identifier and other
          information needed to interact with the authorization server. In
          this case, no client identifier for the authorization server is packaged
          with the client software.</t>
        </section>

        <section anchor="ByDeveloper" title="Registration by the Developer">
          <t>In some cases, the developer (or development software being used
          by the developer) will pre-register the client software with the
          authorization server or a set of authorization servers. In this
          case, the client identifier value(s) for the authorization server(s) can be
          packaged with the client software.</t>
        </section>
      </section>

      <section anchor="IDPerInstanceOrSoftware"
               title="Client ID per Client Instance or per Client Software">
        <section anchor="IDPerInstance"
                 title="Client ID per Client Software Instance">
          <t>In some cases, each deployed instance of a piece of client
          software will dynamically register and obtain distinct client identifier
          values. This can be advantageous, for instance, if the code flow is
          being used, as it also enables each client instance to have its own
          client secret. This can be useful for native clients, which cannot
          maintain the secrecy of a client secret value packaged with the
          software, but which may be able to maintain the secrecy of a
          per-instance client secret.</t>
        </section>

        <section anchor="SharedID"
                 title="Client ID Shared Among All Instances of Client Software">
          <t>In some cases, each deployed instance of a piece of client
          software will share a common client identifier value. For instance, this is
          often the case for in-browser clients using the implicit flow, when
          no client secret is involved. Particular authorization servers might
          choose, for instance, to maintain a mapping between software
          statement values and client identifier values, and return the same client identifier
          value for all registration requests for a particular piece of
          software. The circumstances under which an authorization server
          would do so, and the specific software statement characteristics
          required in this case, are beyond the scope of this
          specification.</t>
        </section>
      </section>

      <section anchor="StatefulOrStateless"
               title="Stateful or Stateless Registration">
        <section anchor="Stateful" title="Stateful Client Registration">
          <t>In some cases, authorization servers will maintain state about
          registered clients, typically indexing this state using the client identifier
	  value. This state would typically include the client metadata
          values associated with the client registration, and possibly other
          state specific to the authorization server's implementation. When
          stateful registration is used, operations to support retrieving
          and/or updating this state may be supported.
	  One possible set of operations upon stateful registrations is described in the
          <xref target="OAuth.Registration.Management"/> specification.</t>
        </section>

        <section anchor="Stateless" title="Stateless Client Registration">
          <t>In some cases, authorization servers will be implemented in a
          manner the enables them to not maintain any local state about
          registered clients. One means of doing this is to encode all the
          registration state in the returned client identifier value, and possibly
          encrypting the state to the authorization server to maintain the
          confidentiality and integrity of the state.</t>
        </section>
      </section>
    </section>

    <section anchor="Acknowledgments" 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: Amanda Anganes, Derek Atkins, Tim Bray,
      Domenico Catalano, Donald Coffin, Vladimir Dzhuvinov, George Fletcher,
      Thomas Hardjono, Phil Hunt, William Kim, Torsten Lodderstedt, Eve Maler,
      Josh Mandel, Nov Matake, Tony Nadalin, Nat Sakimura, Christian Scholz,
      and Hannes Tschofenig.</t>
    </section>

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

      <t>
	-18
	<list style="symbols">
          <t>
	    Corrected an example HTTP response status code to be 201 Created.
	  </t>
	  <t>
	    Said more about who issues and uses initial access tokens and software statements.
	  </t>
	  <t>
	    Stated that the use of an initial access token is required when
	    the authorization server limits the parties that can register a client.
	  </t>
	  <t>
	    Stated that the implementation and use of all client metadata fields is OPTIONAL,
	    other than <spanx style="verb">redirect_uris</spanx>,
	    which MUST be used for redirect-based flows and implemented
	    to fulfill the requirement in Section 2 of OAuth 2.0.
	  </t>
	  <t>
	    Added the <spanx style="verb">application_type</spanx> metadata value,
	    which had somehow been omitted.
	  </t>
	  <t>
	    Added missing default metadata values, which had somehow been omitted.
	  </t>
	  <t>
	    Clarified that the <spanx style="verb">software_id</spanx> is ultimately
	    asserted by the client developer.
	  </t>
	  <t>
	    Clarified that the <spanx style="verb">error</spanx> member is required in error responses,
	    <spanx style="verb">error_description</spanx> member is optional,
	    and other members may be present.
	  </t>
	  <t>
	    Added security consideration about registrations with duplicate
	    <spanx style="verb">software_id</spanx> and
	    <spanx style="verb">software_version</spanx> values.
	  </t>
        </list>
      </t>

      <t>
	-17
        <list style="symbols">
          <t>Merged draft-ietf-oauth-dyn-reg-metadata back into this document.</t>

          <t>Removed "Core" from the document title.</t>

          <t>Explicitly state that all metadata members are optional.</t>

          <t>Clarified language around software statements for use in
          registration context.</t>

          <t>Clarified that software statements need to be digitally signed or MACed.</t>

          <t>Added a <spanx style="verb">jwks</spanx> metadata parameter
	  to parallel the <spanx style="verb">jwks_uri</spanx> parameter.</t>

          <t>Removed normative language from terminology.</t>

          <t>Expanded abstract and introduction.</t>

          <t>Addressed review comments from several working group members.</t>
        </list></t>

      <t>-16 <list style="symbols">
          <t>Replaced references to draft-jones-oauth-dyn-reg-metadata and
          draft-jones-oauth-dyn-reg-management with
          draft-ietf-oauth-dyn-reg-metadata and
          draft-ietf-oauth-dyn-reg-management.</t>

          <t>Addressed review comments by Phil Hunt and Tony Nadalin.</t>
        </list></t>

      <t>-15 <list style="symbols">
          <t>Partitioned the Dynamic Client Registration specification into
          core, metadata, and management specifications. This built on work
          first published as draft-richer-oauth-dyn-reg-core-00 and
          draft-richer-oauth-dyn-reg-management-00.</t>

          <t>Added the ability to use Software Statements. This built on work
          first published as draft-hunt-oauth-software-statement-00 and
          draft-hunt-oauth-client-association-00.</t>

          <t>Created the IANA OAuth Registration Client Metadata registry for
          registering Client Metadata values.</t>

          <t>Defined Client Instance term and stated that multiple instances
          can use the same client identifier value under certain circumstances.</t>

          <t>Rewrote the introduction.</t>

          <t>Rewrote the Use Cases appendix.</t>
        </list></t>

      <t>-14</t>

      <t><list style="symbols">
          <t>Added software_id and software_version metadata fields</t>

          <t>Added direct references to RFC6750 errors in read/update/delete
          methods</t>
        </list></t>

      <t>-13</t>

      <t><list style="symbols">
          <t>Fixed broken example text in registration request and in delete
          request</t>

          <t>Added security discussion of separating clients of different
          grant types</t>

          <t>Fixed error reference to point to RFC6750 instead of RFC6749</t>

          <t>Clarified that servers must respond to all requests to
          configuration endpoint, even if it's just an error code</t>

          <t>Lowercased all Terms to conform to style used in RFC6750</t>
        </list></t>

      <t>-12</t>

      <t><list style="symbols">
          <t>Improved definition of Initial Access Token</t>

          <t>Changed developer registration scenario to have the Initial
          Access Token gotten through a normal OAuth 2.0 flow</t>

          <t>Moved non-normative client lifecycle examples to appendix</t>

          <t>Marked differentiating between auth servers as out of scope</t>

          <t>Added protocol flow diagram</t>

          <t>Added credential rotation discussion</t>

          <t>Called out Client Registration Endpoint as an OAuth 2.0 Protected
          Resource</t>

          <t>Cleaned up several pieces of text</t>
        </list></t>

      <t>-11</t>

      <t><list style="symbols">
          <t>Added localized text to registration request and response
          examples.</t>

          <t>Removed <spanx style="verb">client_secret_jwt</spanx> and <spanx
          style="verb">private_key_jwt</spanx>.</t>

          <t>Clarified <spanx style="verb">tos_uri</spanx> and <spanx
          style="verb">policy_uri</spanx> definitions.</t>

          <t>Added the OAuth Token Endpoint Authentication Methods registry
          for registering <spanx style="verb">token_endpoint_auth_method</spanx>
          metadata values.</t>

          <t>Removed uses of non-ASCII characters, per RFC formatting
          rules.</t>

          <t>Changed <spanx style="verb">expires_at</spanx> to <spanx
          style="verb">client_secret_expires_at</spanx> and <spanx
          style="verb">issued_at</spanx> to <spanx style="verb">client_id_issued_at</spanx>
          for greater clarity.</t>

          <t>Added explanatory text for different credentials (Initial Access
          Token, Registration Access Token, Client Credentials) and what
          they're used for.</t>

          <t>Added Client Lifecycle discussion and examples.</t>

          <t>Defined Initial Access Token in Terminology section.</t>
        </list></t>

      <t>-10</t>

      <t><list style="symbols">
          <t>Added language to point out that scope values are
          service-specific</t>

          <t>Clarified normative language around client metadata</t>

          <t>Added extensibility to token_endpoint_auth_method using absolute
          URIs</t>

          <t>Added security consideration about registering redirect URIs</t>

          <t>Changed erroneous 403 responses to 401's with notes about token
          handling</t>

          <t>Added example for initial registration credential</t>
        </list></t>

      <t>-09</t>

      <t><list style="symbols">
          <t>Added method of internationalization for Client Metadata
          values</t>

          <t>Fixed SAML reference</t>
        </list></t>

      <t>-08</t>

      <t><list style="symbols">
          <t>Collapsed jwk_uri, jwk_encryption_uri, x509_uri, and
          x509_encryption_uri into a single jwks_uri parameter</t>

          <t>Renamed grant_type to grant_types since it's a plural value</t>

          <t>Formalized name of "OAuth 2.0" throughout document</t>

          <t>Added JWT Bearer Assertion and SAML 2 Bearer Assertion to example
          grant types</t>

          <t>Added response_types parameter and explanatory text on its use
          with and relationship to grant_types</t>
        </list></t>

      <t>-07</t>

      <t><list style="symbols">
          <t>Changed registration_access_url to registration_client_uri</t>

          <t>Fixed missing text in 5.1</t>

          <t>Added Pragma: no-cache to examples</t>

          <t>Changed "no such client" error to 403</t>

          <t>Renamed Client Registration Access Endpoint to Client
          Configuration Endpoint</t>

          <t>Changed all the parameter names containing "_url" to instead use
          "_uri"</t>

          <t>Updated example text for forming Client Configuration Endpoint
          URL</t>
        </list></t>

      <t>-06</t>

      <t><list style="symbols">
          <t>Removed secret_rotation as a client-initiated action, including
          removing client secret rotation endpoint and parameters.</t>

          <t>Changed _links structure to single value
          registration_access_url.</t>

          <t>Collapsed create/update/read responses into client info
          response.</t>

          <t>Changed return code of create action to 201.</t>

          <t>Added section to describe suggested generation and composition of
          Client Registration Access URL.</t>

          <t>Added clarifying text to PUT and POST requests to specify JSON in
          the body.</t>

          <t>Added Editor's Note to DELETE operation about its inclusion.</t>

          <t>Added Editor's Note to registration_access_url about alternate
          syntax proposals.</t>
        </list></t>

      <t>-05</t>

      <t><list style="symbols">
          <t>changed redirect_uri and contact to lists instead of space
          delimited strings</t>

          <t>removed operation parameter</t>

          <t>added _links structure</t>

          <t>made client update management more RESTful</t>

          <t>split endpoint into three parts</t>

          <t>changed input to JSON from form-encoded</t>

          <t>added READ and DELETE operations</t>

          <t>removed Requirements section</t>

          <t>changed token_endpoint_auth_type back to
          token_endpoint_auth_method to match OIDC who changed to match us</t>
        </list></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-parameter 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>
  </back>
</rfc>

PAFTECH AB 2003-20262026-04-23 03:37:45