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Open Authentication Protocol                                  A. Parecki
Internet-Draft                                                      Okta
Intended status: Standards Track                       February 22, 2021
Expires: August 26, 2021


                 OAuth 2.0 Client Intermediary Metadata
          draft-parecki-oauth-client-intermediary-metadata-03

Abstract

   This specification defines a mechanism for including information
   about additional parties involved in an OAuth transaction by adding a
   new section to the OAuth 2.0 Dynamic Client Registration request, as
   well as requires that authorization servers surface this information
   to users during an OAuth transaction.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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   This Internet-Draft will expire on August 26, 2021.

Copyright Notice

   Copyright (c) 2021 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
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   described in the Simplified BSD License.



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1.  Introduction

   In some applications of OAuth, there may be multiple legal entities
   which have access to or process data retrieved by an OAuth client.
   In the traditional OAuth model, a "client_id" represents only a
   single application, and so the OAuth consent screen lists just one
   third party: the OAuth client.

   In this situation, in order to comply with various local laws and
   regulations, the user needs to be informed by the authorization
   server of the list of entities that will have access to their data
   after authorizing the client.

   The existing Dynamic Client Registration ([RFC7591]) specification
   lacks a mechanism for communicating a list of additional parties that
   may have access to the user's data.

   This specification extends [RFC7591] and [RFC7592] to define a
   mechanism for including information about the additional parties
   involved in an OAuth transaction by including information about the
   additional intermediaries into the Dynamic Client Registration
   request.  This specification also defines requirements of the OAuth
   authorization server to present this information about the additional
   parties in the OAuth consent screen during an OAuth transaction.

2.  Notational Conventions

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in
   [RFC2119].

   Unless otherwise noted, all the protocol parameter names and values
   are case sensitive.

3.  Terminology

   In addition to the terms defined in referenced specifications, this
   document uses the following terms:

   "OAuth":  In this document, "OAuth" refers to OAuth 2.0, [RFC6749].

   "Client":  "Client" has the same definition as in OAuth 2.0, but is
      worth pointing out that the client in this context may be operated
      by a different legal entity than is described by the client name.

   "Intermediary":  One or more entities that the user's data will pass
      through or be shared with by using the OAuth client.  This



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      information is voluntarily provided by the OAuth client, and is
      typically enforced by a business relationship between the
      organization providing the Client and the organization providing
      the Resource Server.

4.  Client Intermediary Metadata

   Registered client intermediaries have a set of metadata values
   associated with the client identifier of the client that represents
   them in the OAuth transaction, such as a user-visible name, logo, and
   URL.

   Like the OAuth client metadata defined in [RFC7591] and [RFC7592],
   these metadata values are used in the following ways:

   o  as input values to registration and update requests, and

   o  as output values in registration responses.

   These values are used by the authorization server when displaying the
   OAuth consent screen to the end user, to inform them of all the
   additional parties that will be handling the user's data upon
   approval.

   The following metadata fields are defined by this specification.  The
   implementation and use of the fields is OPTIONAL unless stated
   otherwise.  All data member types (strings, arrays, numbers) are
   defined in terms of their JSON ([RFC7159]) representations.

   Some fields are expected to be displayed in the OAuth consent UI and
   are designated accordingly.

   "name"

   REQUIRED.  A human-readable name of intermediary party.
   Authorization servers MUST display this field to the end user on the
   OAuth consent screen.

   "description"

   OPTIONAL.  A human-readable description of the intermediary.  This is
   not intended to be displayed in the OAuth consent screen.

   "uri"

   A URL string of a web page providing information about the
   intermediary.  If present, the authorization server SHOULD display
   this URL to the end user in a clickable fashion.  It is RECOMMENDED



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   that clients always send this field.  The value of this field MUST
   point to a valid web page.

   "logo_uri"

   A URL string that references a logo for this intermediary.  If
   present, the authorization server SHOULD display this image to the
   end user in the OAuth consent screen.  The value of this field MUST
   be a valid image file.

   "contacts"

   Array of strings representing ways to contact people responsible for
   this intermediary, typically email addresses or phone numbers.  The
   authorization server MAY display these to the end user in the OAuth
   consent screen.  See Section 6 of [RFC7591] for information on
   Privacy Considerations.

5.  Client Registration Endpoint

   The client registration endpoint is described in Section 3 of
   [RFC7591].

   Since this specification provides a mechanism for a client to assert
   information about additional parties other than itself, the
   registration endpoint MUST be protected by an OAuth 2.0 access token
   obtained by the client.  The method by which the initial access token
   is obtained by the client or developer is out of scope of this
   specification, but is likely to be obtained using the client
   credentials grant or manual out-of-band registration.

5.1.  Client Registration Request

   This specification extends the client registration request defined in
   [RFC7591].

   This operation registers a combination of client and one or more
   intermediaries with an authorization server.  The authorization
   server assigns a unique client identifier (and optionally a client
   secret) that represents the combination of all the entities described
   in the registration request.

   To register, the client or developer sends an HTTP POST as described
   in Section 3.1 of [RFC7591], with an additional property named
   "intermediaries" with a JSON array of objects of each intermediary's
   registration information.  The properties of the object are described
   above in Section 4.




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   For example, the client could send the following registration request
   to the client registration endpoint using its OAuth 2.0 access token
   it has previously obtained using the client credentials grant.

   The following is a non-normative example request:

       POST /register HTTP/1.1
       Content-Type: application/json
       Accept: application/json
       Host: server.example.com
       Authorization: Bearer 8IGFGXKXZBV5LL38Y3X1

       {
         "client_name": "User-Recognizable App Name",
         "redirect_uris": [
           "https://client.example.org/callback"
         ],
         "client_uri": "https://example.net/",
         "logo_uri": "https://example.net/logo.png",
         "contacts": [
           "support@example.net"
         ],
         "intermediaries": [
           {
             "name": "Partner App Name",
             "description": "An application that may also receive
               this user's data when the user authorizes the client",
             "uri": "https://partner.example/",
             "logo_uri": "https://partner.example/logo.png",
             "contacts": [
               "support@partner.example"
             ]
           }
         ]
       }

5.2.  Client Registration Response

   This specification extends the client information response defined in
   [RFC7591] and [RFC7592].

   Upon a successful registration request, the authorization server
   returns a client identifier for the combination of the client and any
   intermediaries specified in the request.

   In addition to the response fields defined in Section 3.2 of
   [RFC7591] and Section 3 of [RFC7592], the response MUST also contain
   all registered metadata about the intermediaries.  The authorization



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   server MAY reject or replace any of the requested metadata values
   submitted during the registration and substitute them with suitable
   values.

   The following is a non-normative example response of a successful
   registration:

    HTTP/1.1 201 Created
    Content-Type: application/json
    Cache-Control: no-store
    Pragma: no-cache

    {
      "client_id": "V8tvEkZWhDAdxSaKGUJZ",
      "client_secret": "SpsuwZIxnp8bBEhp5sk1EKiIKTZ4X4DKU",
      "grant_types": ["authorization_code", "refresh_token"],
      "token_endpoint_auth_method": "client_secret_basic",
      "registration_client_uri": "https://server.example.com/client/tmzaAMkyWlH3",
      "registration_access_token": "MphaAqDaZT86C93ENWRZcf3dfU2dW6POASo8dFXa",
      "client_name": "User-Recognizable App Name",
      "client_uri": "https://example.net/",
      "redirect_uris": [
        "https://client.example.org/callback"
      ],
      "contacts": [
        "support@example.net"
      ],
      "intermediaries": [
        {
          "name": "Partner App Name",
          "description": "An application that may also receive
            this user's data when the user authorizes the client",
          "uri": "https://partner.example/",
          "logo_uri": "https://partner.example/logo.png",
          "contacts": [
            "support@partner.example"
          ]
        }
      ]
    }

   The "registration_client_uri" and "registration_access_token"
   properties are required in order to support updating and deleting
   this client as described in [RFC7592].







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5.3.  Client Read Request

   This specification extends the client read request defined in
   [RFC7592] to include the additional metadata properties in the
   response that describe the intermediaries.  No additional behavior is
   prescribed by this specification.

5.4.  Client Update Request

   This specification extends the client update request defined in
   [RFC7592] to be able to update the additional metadata properties
   that describe the intermediaries.

   The additional properties are provided in the update request in the
   same format as in the initial registration request.

   Since these values were asserted by the client in the initial
   registration, there is no need to prescribe any additional security
   model around the ability to update them, even though these represent
   additional parties.

5.5.  Client Delete Request

   No new behavior is prescribed for delete requests beyond that defined
   in [RFC7592].

6.  Providing Intermediaty Details in the Authorization Request

   When the authorization server begins a request from an OAuth client
   identifier that has been registered with additional intermediary
   information, it MUST display the additional parties in the consent UI
   visible to the end user.

   The authorization server chooses how best to display the additional
   information, but it MUST include at least the name of the
   intermediaries and client, and SHOULD include the logo of each as
   well.

7.  Security Considerations

   As this extends [RFC7591], all security considerations from that
   draft apply here as well.

   Specifically, if the authorization server supports open client
   registration without any authentication, it must be extremely careful
   with any URLs received in the registration request such as
   "logo_uri", "tos_uri", and "uri", as these values may be displayed to
   end users.  [RFC7591] recommends requiring that these URIs have a



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   matching host and scheme as the defined "redirect_uri"s, and that
   they are resolvable URIs.  See section 5 of [RFC7591] for more
   details.

8.  Acknowledgements

   The author would like to thank Ryan Christiansen and Preston
   McFarland for their initial contributions of the concepts behind this
   specification.  The author would also like to thank Don Cardinal,
   Ryan Christiansen and Preston McFarland for their reviews of this
   specification, as well as Anil Mahalaha and other members of the
   Financial Data Exchange working group.  Additionally the work of the
   OAuth Working Group on the referenced and related specifications that
   this specification builds upon is much appreciated.

9.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC6749]  Hardt, D., Ed., "The OAuth 2.0 Authorization Framework",
              RFC 6749, DOI 10.17487/RFC6749, October 2012,
              <https://www.rfc-editor.org/info/rfc6749>.

   [RFC7159]  Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
              Interchange Format", RFC 7159, DOI 10.17487/RFC7159, March
              2014, <https://www.rfc-editor.org/info/rfc7159>.

   [RFC7591]  Richer, J., Ed., Jones, M., Bradley, J., Machulak, M., and
              P. Hunt, "OAuth 2.0 Dynamic Client Registration Protocol",
              RFC 7591, DOI 10.17487/RFC7591, July 2015,
              <https://www.rfc-editor.org/info/rfc7591>.

   [RFC7592]  Richer, J., Ed., Jones, M., Bradley, J., and M. Machulak,
              "OAuth 2.0 Dynamic Client Registration Management
              Protocol", RFC 7592, DOI 10.17487/RFC7592, July 2015,
              <https://www.rfc-editor.org/info/rfc7592>.

Author's Address

   Aaron Parecki
   Okta

   Email: aaron@parecki.com
   URI:   https://aaronparecki.com




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