REGEXT Working Group                                       S. Hollenbeck
Internet-Draft                                             Verisign Labs
Intended status: Standards Track                        24 February                           23 March 2022
Expires: 28 August 24 September 2022

   Federated Authentication for the Registration Data Access Protocol
                      (RDAP) using OpenID Connect
                    draft-ietf-regext-rdap-openid-11
                    draft-ietf-regext-rdap-openid-12

Abstract

   The Registration Data Access Protocol (RDAP) provides "RESTful" web
   services to retrieve registration metadata from domain name and
   regional internet registries.  RDAP allows a server to make access
   control decisions based on client identity, and as such it includes
   support for client identification features provided by the Hypertext
   Transfer Protocol (HTTP).  Identification methods that require
   clients to obtain and manage credentials from every RDAP server
   operator present management challenges for both clients and servers,
   whereas a federated authentication system would make it easier to
   operate and use RDAP without the need to maintain server-specific
   client credentials.  This document describes a federated
   authentication system for RDAP based on OpenID Connect.

Status of This Memo

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   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on 28 August 24 September 2022.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Problem Statement . . . . . . . . . . . . . . . . . . . .   3
     1.2.  Proposal  . . . . . . . . . . . . . . . . . . . . . . . .   4
   2.  Conventions Used in This Document . . . . . . . . . . . . . .   4
   3.  Federated Authentication for RDAP . . . . . . . . . . . . . .   4
     3.1.  RDAP and OpenID Connect . . . . . . . . . . . . . . . . .   5
       3.1.1.  Terminology . . . . . . . . . . . . . . . . . . . . .   5
       3.1.2.  Overview  . . . . . . . . . . . . . . . . . . . . . .   5
       3.1.3.  RDAP Authentication and Authorization Steps . . . . .   6
         3.1.3.1.  Provider Discovery  . . . . . . . . . . . . . . .   7
         3.1.3.2.  Authentication Request  . . . . . . . . . . . . .   7
         3.1.3.3.  End-User Authorization  . . . . . . . . . . . . .   8
         3.1.3.4.  Authorization Response and Validation . . . . . .   8
         3.1.3.5.  Token Processing  . . . . . . . . . . . . . . . .   8
         3.1.3.6.  Delivery of User Information  . . . . . . . . . .   8
       3.1.4.  Specialized Claims for RDAP . . . . . . . . . . . . .   9
         3.1.4.1.  Stated Purpose  . . . . . . . . . . . . . . . . .   9
         3.1.4.2.  Do Not Track  . . . . . . . . . . . . . . . . . .  10
   4.  Protocol Parameters . . . . . . . . . . . . . . . . . . . . .  10
     4.1.  Data Structures . . . . . . . . . . . . . . . . . . . . .  11
       4.1.1.  Session . . . . . . . . . . . . . . . . . . . . . . .  11
       4.1.2.  Device Info . . . . . . . . . . . . . . . . . . . . .  12
     4.2.  Client Login  . . . . . . . . . . . . . . . . . . . . . .  13
       4.2.1.  Clients with Limited User Interfaces  . . . . . . . .  15
         4.2.1.1.  UI-constrained Client Login . . . . . . . . . . .  15
         4.2.1.2.  UI-constrained Client Login Polling . . . . . . .  16  17
     4.3.  Session Status  . . . . . . . . . . . . . . . . . . . . .  17
     4.4.  Session Refresh . . . . . . . . . . . . . . . . . . . . .  18
     4.5.  Client Logout . . . . . . . . . . . . . . . . . . . . . .  20
     4.6.  Parameter Processing  . . . . . . . . . . . . . . . . . .  21
   5.  Token Exchange  . . . . . . . . . . . . . . . . . . . . . . .  21
   6.  RDAP Query Processing . . . . . . . . . . . . . . . . . . . .  21
   7.  RDAP Conformance  . . . . . . . . . . . . . . . . . . . . . .  22
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  22
     8.1.  RDAP Extensions Registry  . . . . . . . . . . . . . . . .  22
     8.2.  JSON Web Token Claims Registry  . . . . . . . . . . . . .  23
     8.3.  RDAP Query Purpose Registry . . . . . . . . . . . . . . .  23

   9.  Implementation Status . . . . . . . . . . . . . . . . . . . .  25  26
     9.1.  Editor Implementation . . . . . . . . . . . . . . . . . .  26  27
     9.2.  Verisign Labs . . . . . . . . . . . . . . . . . . . . . .  26  27
     9.3.  Viagenie  . . . . . . . . . . . . . . . . . . . . . . . .  27  28
   10. Security Considerations . . . . . . . . . . . . . . . . . . .  27  28
     10.1.  Authentication and Access Control  . . . . . . . . . . .  28  29
   11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  28  29
   12. References  . . . . . . . . . . . . . . . . . . . . . . . . .  28  29
     12.1.  Normative References . . . . . . . . . . . . . . . . . .  28  29
     12.2.  Informative References . . . . . . . . . . . . . . . . .  30  31
   Appendix A.  Change Log . . . . . . . . . . . . . . . . . . . . .  31  32
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  31  32

1.  Introduction

   The Registration Data Access Protocol (RDAP) provides "RESTful" web
   services to retrieve registration metadata from domain name and
   regional internet registries.  RDAP allows a server to make access
   control decisions based on client identity, and as such it includes
   support for client identification features provided by the Hypertext
   Transfer Protocol (HTTP) [RFC7230].

   RDAP is specified in multiple documents, including "HTTP Usage in the
   Registration Data Access Protocol (RDAP)" [RFC7480], "Security
   Services for the Registration Data Access Protocol (RDAP)" [RFC7481],
   "Registration Data Access Protocol Query Format" [RFC9082], and "JSON
   Responses for the Registration Data Access Protocol (RDAP)"
   [RFC9083].  RFC 7481 describes client identification and
   authentication services that can be used with RDAP, but it does not
   specify how any of these services can (or should) be used with RDAP.

1.1.  Problem Statement

   The traditional "user name and password" authentication method does
   not scale well in the RDAP ecosystem.  Assuming that all domain name
   and address registries will eventually provide RDAP service, it is
   impractical and inefficient for users to secure login credentials
   from the hundreds of different server operators.  Authentication
   methods based on user names and passwords do not provide information
   that describes the user in sufficient detail (while protecting the
   personal privacy of the user) for server operators to make fine-
   grained access control decisions based on the user's identity.  The
   authentication system used for RDAP needs to address all of these
   needs.

1.2.  Proposal

   A basic level of RDAP service can be provided to users who possess an
   identifier issued by a recognized provider who is able to
   authenticate and validate the user.  The identifiers issued by social
   media services, for example, can be used.  Users who require higher
   levels of service (and who are willing to share more information
   about them self to gain access to that service) can secure
   identifiers from specialized providers who are or will be able to
   provide more detailed information about the user.  Server operators
   can then make access control decisions based on the identification
   information provided by the user.

   A federated authentication system in which an RDAP server outsources
   identification and authentication services to a trusted OpenID
   Provider would make it easier to operate and use RDAP by re-using
   existing identifiers to provide a basic level of access.  It can also
   provide the ability to collect additional user identification
   information, and that information can be shared with the consent of
   the user.  This type of system allows an RDAP server to make access
   control decisions based on the nature of a query and the identity,
   authentication, and authorization information that is received from
   the OpenID Provider.  This document describes a federated
   authentication system for RDAP based on OpenID Connect [OIDC] that
   meets all of these needs.

2.  Conventions Used in This Document

   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 BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

3.  Federated Authentication for RDAP

   RDAP itself does not include native security services.  Instead, RDAP
   relies on features that are available in other protocol layers to
   provide needed security services including access control,
   authentication, authorization, availability, data confidentiality,
   data integrity, and identification.  A description of each of these
   security services can be found in "Internet Security Glossary,
   Version 2" [RFC4949].  This document focuses on a federated
   authentication system for RDAP that provides services for
   authentication, authorization, and identification, allowing a server
   operator to make access control decisions.  Section 3 of RFC 7481
   [RFC7481] describes general considerations for RDAP access control,
   authentication, and authorization.

   The traditional client-server authentication model requires clients
   to maintain distinct credentials for every RDAP server.  This
   situation can become unwieldy as the number of RDAP servers
   increases.  Federated authentication mechanisms allow clients to use
   one credential to access multiple RDAP servers and reduce client
   credential management complexity.

3.1.  RDAP and OpenID Connect

   OpenID Connect 1.0 [OIDCC] is a decentralized, single sign-on (SSO)
   federated authentication system that allows users to access multiple
   web resources with one identifier instead of having to create
   multiple server-specific identifiers.  Users acquire identifiers from
   OpenID Providers, or OPs.  Relying Parties, or RPs, are applications
   (such as RDAP) that outsource their user authentication function to
   an OP.  OpenID Connect is built on top of the authorization framework
   provided by the OAuth 2.0 [RFC6749] protocol.

   The OAuth authorization framework describes a method for users to
   access protected web resources without having to hand out their
   credentials.  Instead, clients are issued Access Tokens by
   authorization servers with the permission of the resource owners.
   Using OpenID Connect and OAuth, multiple RDAP servers can form a
   federation and clients can access any server in the federation by
   providing one credential registered with any OP in that federation.
   The OAuth authorization framework is designed for use with HTTP and
   thus can be used with RDAP.

3.1.1.  Terminology

   This document uses the terms "client" and "server" defined by RDAP
   [RFC7480].  An RDAP client performs the role of an OpenID Connect
   Core [OIDCC] Entity or End-User.  An RDAP server performs the role of
   an OpenID Connect Core Relying Party (RP).  Additional terms from
   Section 1.2 of the OpenID Connect Core specification are incorporated
   by reference.

3.1.2.  Overview

   At a high level, RDAP authentication of a browser-like client using
   OpenID Connect requires completion of the following steps:

   1.   An RDAP client sends an RDAP "help" query to an RDAP server to
        determine the type of OpenID Authorization Server that's used by
        the RDAP server.  This information is returned in the
        rdapConformance section of the response.  A value of
        "rdap_openidc_local_level_0" indicates that the server uses a
        local Authorization Server.  A value of
        "rdap_openidc_remote_level_0" indicates that the server uses a
        remote Authorization Server.
   2.   An RDAP client (acting as an OpenID End-User) sends an RDAP
        "login" request to an RDAP server as described in Section 4.2.
   3.   The RDAP server (acting as an OpenID Relying Party (RP))
        prepares an Authentication Request containing the desired
        request parameters.
   4.   The RDAP server sends the RDAP client and Authentication Request
        to an Authorization Server operated by an OpenID Provider (OP)
        using an HTTP redirect.
   5.   The Authorization Server authenticates the End-User.
   6.   The Authorization Server obtains End-User consent/authorization.
   7.   The Authorization Server sends the RDAP Client back to the RDAP
        server with an Authorization Code using an HTTP redirect.
   8.   The RDAP server requests a response using the Authorization Code
        at the Token Endpoint.
   9.   The RDAP server receives a response that contains an ID Token
        and Access Token in the response body.
   10.  The RDAP server validates the ID Token and retrieves the claims
        associated with the End-User's identity.

   The RDAP server can then make identification, authorization, and
   access control decisions based on End-User identity information and
   local policies.  Note that OpenID Connect describes different process
   flows for other types of clients, such as script-based or command
   line clients.

3.1.3.  RDAP Authentication and Authorization Steps

   End-Users MUST possess an identifier (an OpenID) issued by an OP to
   use OpenID Connect with RDAP.  An OP SHOULD include support for the
   claims described in Section 3.1.4 to provide additional information
   needed for RDAP End-User authorization.  OpenID Connect requires RPs
   to register with OPs to use OpenID Connect services for an End-User.
   The registration process is often completed using out-of-band
   methods, but it is also possible to use the automated method
   described by the "OpenID Connect Dynamic Client Registration"
   protocol [OIDCR].  The parties involved can use any method that is
   mutually acceptable.

3.1.3.1.  Provider Discovery

   An RDAP server/RP needs to be able to map an End-User's identifier to
   an OP.  This can be accomplished using the OPTIONAL "OpenID Connect
   Discovery" protocol [OIDCD], but that protocol is not widely
   implemented.  Out-of-band methods are also possible and can be more
   dependable.  For example, an RP can support a limited number of OPs
   and maintain internal associations of those identifiers with the OPs
   that issued them.  An RP can also ask an End-User to identify the OP
   that issued their identifier as part of an RDAP query workflow.  In
   this case, the RP will need to maintain state for the association
   between the user's identifier and the OP in order to process later
   queries that rely on passing the access token and user identifier as
   authorization parameters.  An RP MAY use any provider discovery
   approach that is suitable for its operating environment.

3.1.3.2.  Authentication Request

   Once the OP is known, an RP MUST form an Authentication Request and
   send it to the OP as described in Section 3 of the OpenID Connect
   Core protocol [OIDCC].  The authentication path followed
   (authorization, implicit, or hybrid) will depend on the
   Authentication Request response_type set by the RP.  The remainder of
   the processing steps described here assume that the Authorization
   Code Flow is being used by setting "response_type=code" in the
   Authentication Request.

   The benefits of using the Authorization Code Flow for authenticating
   a human user are described in Section 3.1 of the OpenID Connect Core
   protocol.  The Implicit Flow is more commonly used by clients
   implemented in a web browser using a scripting language; it is
   described in Section 3.2 of the OpenID Connect Core protocol.  The
   Hybrid Flow (described in Section 3.3 of the OpenID Connect Core
   protocol) combines elements of the Authorization and Implicit Flows
   by returning some tokens from the Authorization Endpoint and others
   from the Token Endpoint.

   An Authentication Request can contain several parameters.  REQUIRED
   parameters are specified in Section 3.1.2.1 of the OpenID Connect
   Core protocol [OIDCC].  Apart from these parameters, it is
   RECOMMENDED that the RP include the optional "login_hint" parameter
   in the request, with the value being that of the "id" query parameter
   of the End-User's RDAP "login" request.  Passing the "login_hint"
   parameter allows a client to pre-fill login form information, so
   logging in can be more convenient for users.  Other parameters MAY be
   included.

   The OP receives the Authentication Request and attempts to validate
   it as described in Section 3.1.2.2 of the OpenID Connect Core
   protocol [OIDCC].  If the request is valid, the OP attempts to
   authenticate the End-User as described in Section 3.1.2.3 of the
   OpenID Connect Core protocol [OIDCC].  The OP returns an error
   response if the request is not valid or if any error is encountered.

3.1.3.3.  End-User Authorization

   After the End-User is authenticated, the OP MUST obtain authorization
   information from the End-User before releasing information to the
   RDAP Server/RP.  This process is described in Section 3.1.2.4 of the
   OpenID Connect Core protocol [OIDCC].

3.1.3.4.  Authorization Response and Validation

   After the End-User is authenticated, the OP will send a response to
   the RP that describes the result of the authorization process in the
   form of an Authorization Grant.  The RP MUST validate the response.
   This process is described in Sections 3.1.2.5 - 3.1.2.7 of the OpenID
   Connect Core protocol [OIDCC].

3.1.3.5.  Token Processing

   The RP sends a Token Request using the Authorization Grant to a Token
   Endpoint to obtain a Token Response containing an Access Token, ID
   Token, and an OPTIONAL Refresh Token.  The RP MUST validate the Token
   Response.  This process is described in Section 3.1.3 of the OpenID
   Connect Core protocol [OIDCC].

3.1.3.6.  Delivery of User Information

   The set of claims can be retrieved by sending a request to a UserInfo
   Endpoint using the Access Token.  The claims MAY be returned in the
   ID Token.  The process of retrieving claims from a UserInfo Endpoint
   is described in Section 5.3 of the OpenID Connect Core protocol
   [OIDCC].

   OpenID Connect specifies a set of standard claims in Section 5.1.
   Additional claims for RDAP are described in Section 3.1.4.

3.1.4.  Specialized Claims for RDAP

   OpenID Connect claims are pieces of information used to make
   assertions about an entity.  Section 5 of the OpenID Connect Core
   protocol [OIDCC] describes a set of standard claims that can be used
   to identify a person.  Section 5.1.2 notes that additional claims MAY
   be used, and it describes a method to create them.  The set of claims
   that are specific to RDAP are associated with an OAuth scope request
   parameter value (see Section 3.3 of RFC 6749 ([RFC6749])) of "rdap".

3.1.4.1.  Stated Purpose

   There are communities of RDAP users and operators who wish to make
   and validate claims about a user's "need to know" when it comes to
   requesting access to a resource.  For example, a law enforcement
   agent or a trademark attorney may wish to be able to assert that they
   have a legal right to access a protected resource, and a server
   operator will need to be able to receive and validate that claim.
   These needs can be met by defining and using an additional "purpose"
   claim.

   The "purpose" claim identifies the purpose for which access to a
   protected resource is being requested.  Use of the "purpose" claim is
   OPTIONAL; processing of this claim is subject to server acceptance of
   the purpose and successful authentication of the End-User.
   Unrecognized purpose values MUST be ignored and the associated query
   MUST be processed as if the unrecognized purpose value was not
   present at all.

   The "purpose" value is a case-sensitive string containing a
   StringOrURI value as specified in Section 2 of the JSON Web Token
   (JWT) specification ([RFC7519]).  An example:

   {"purpose" : "domainNameControl"}

   Purpose values are themselves registered with IANA.  Each entry in
   the registry contains the following fields:

   Value: the purpose string value being registered.  Value strings can
   contain upper case characters from "A" to "Z", lower case ASCII
   characters from "a" to "z", and the underscore ("_") character.
   Value strings contain at least one character and no more than 64
   characters.

   Description: a one- or two-sentence description of the meaning of the
   purpose value, how it might be used, and/or how it should be
   interpreted by clients and servers.

   This registry is operated under the "Specification Required" policy
   defined in RFC 5226 ([RFC5226]).  The set of initial values used to
   populate the registry as described in Section 8.3 are taken from the
   final report (https://www.icann.org/en/system/files/files/final-
   report-06jun14-en.pdf) produced by the Expert Working Group on gTLD
   Directory Services chartered by the Internet Corporation for Assigned
   Names and Numbers (ICANN).

3.1.4.2.  Do Not Track

   There are also communities of RDAP users and operators who wish to
   make and validate claims about a user's wish to not have their
   queries logged, tracked, or recorded.  For example, a law enforcement
   agent may wish to be able to assert that their queries are part of a
   criminal investigation and should not be tracked due to a risk of
   query exposure compromising the investigation, and a server operator
   will need to be able to receive and validate that claim.  These needs
   can be met by defining and using an additional "do not track" claim.

   The "do not track" ("dnt") claim can be used to identify an End-User
   that is authorized to perform queries without the End-User's
   association with those queries being logged, tracked, or recorded by
   the server.  Client use of the "dnt" claim is OPTIONAL.  Server
   operators MUST NOT log, track, or record any association of the query
   and the End-User's identity if the End-User is successfully
   identified and authorized, the "dnt" claim is present, the value of
   the claim is "true", and accepting the claim complies with local
   regulations regarding logging and tracking.

   The "dnt" value is represented as a JSON boolean literal.  An
   example:

   {"dnt" : true}

   No special query tracking processing is required if this claim is not
   present or if the value of the claim is "false".  Use of this claim
   MUST be limited to End-Users who are granted "do not track"
   privileges in accordance with service policies and regulations.
   Specification of these policies and regulations is beyond the scope
   of this document.

4.  Protocol Parameters

   This specification adds the following protocol parameters to RDAP:

   1.  Data structures to return information that describes an
       established session and the information needed to establish a
       session for a UI-constrained device.

   2.  A query parameter to request authentication for a specific End-
       User identity.
   3.  Path segments to start, stop, refresh, and determine the status
       of an authenticated session for a specific End-User identity.

4.1.  Data Structures

   This specification describes two new data structures that are used to
   return information to a client: a "session" data structure that
   contains information that describes an established session, and a
   "deviceInfo" data structure that contains information that describes
   an active attempt to establish a session on a UI-constrained device.

4.1.1.  Session

   The "session" data structure is an array object that contains two sub-
   arrays:
   objects:

   1.  A "userClaims" array object that contains the set of claims associated
       with the End-User's identity, with each claim represented identity as a
       name-value pair in string format. used/requested by the RDAP server
       to make access control decisions.  The set of possible values is
       determined by OP policy.
   2.  A "sessionInfo" array object that contains two name-value pairs: members:
       a.  "tokenExpiration": an integer value that represents the
           number of seconds from the current time for which the Access
           Token remains valid, and
       b.  "tokenRefresh": A boolean value that indicates if the OP
           supports refresh tokens.  As described in RFC 6749 [RFC6749],
           support for refresh tokens is OPTIONAL.

   An example of a "session" data structure:

     "session": {
       "userClaims": {
         "sub": "103892603076825016132",
         "name": "User Person",
         "given_name": "User",
         "family_name": "Person",
         "picture": "https://lh3.example.com/a-/AOh14=s96-c",
         "email": "user@example.com",
         "email_verified": true,
         "locale": "en",
         "purpose": "domainNameControl",
         "dnt": false
       },
       "sessionInfo": {
         "tokenExpiration": 3599,
         "tokenRefresh": true
       }
     }

                                  Figure 1

4.1.2.  Device Info

   The flow described in Section 3.1.3 requires an End-User to interact
   with a server using a user interface that can process HTTP.  This
   will not work well in situations where the client is automated or an
   End-User is using a command line user interface such as curl
   (http://curl.haxx.se/) or wget (https://www.gnu.org/software/wget/).
   This limitation can be addressed using a web browser on a second
   device.  The information that needs to be entered using the web
   browser is contained in the "deviceInfo" data structure.

   The "deviceInfo" data structure is an array object that contains three name-
   value pairs:
   members:

   1.  "verification_url": the URL that the End-User needs to visit
       using the web browser,
   2.  "user_code": the string value that the End-User needs to enter on
       the form presented in the web browser, and
   3.  "expires_in": an integer value that represents the number of
       seconds after which the opportunity to visit the URL and enter
       the user_code will expire.

   An example of a "deviceInfo" data structure:

     "deviceInfo": {
       "verification_url": "https://www.example.com/device",
       "user_code": "NJJQ-GJFC",
       "expires_in": "1800"
     }

                                  Figure 2

4.2.  Client Login

   Client authentication is requested by sending a "session/login"
   request to an RDAP server.  If the RDAP server supports only remote
   Authorization Servers, the "session/login" request MUST include an
   End-User identifier that's delivered using one of two methods: by
   adding a query component to an RDAP request URI using the syntax
   described in Section 3.4 of RFC 3986 [RFC3986], or by including an
   HTTP authorization header for the Basic authentication scheme as
   described in RFC 7617 [RFC7617].  Clients can use either of these
   methods to deliver the End-User identifier to a server that supports
   remote Authorization Servers.  Servers that support remote
   Authorization Servers MUST accept both methods.  If the RDAP server
   supports a local Authorization Server, the End-User identifier MAY be
   omitted.

   The query used to request client authentication is represented as an
   OPTIONAL "key=value" pair using a key value of "id" and a value
   component that contains the client identifier issued by an OP.  An
   example for client identifier "user.idp.example":

   https://example.com/rdap/session/login?id=user.idp.example

   The authorization header for the Basic authentication scheme contains
   a Base64-encoded representation of the client identifier issued by an
   OP.  No password is provided.  An example for client identifier
   "user.idp.example":

   https://example.com/rdap/session/login

   Authorization: Basic dXNlci5pZHAuZXhhbXBsZQ==

   An example for use with a local Authorization Server:

   https://example.com/rdap/session/login
   The response to this request MUST use the response structures
   specified in RFC 9083 [RFC9083].  In addition, the response MUST
   include an indication of the requested operation's success or failure
   in the "notices" data structure (including the client identifier),
   and, if successful, a "session" data structure.

   An example of a successful "session/login" response:

     {
       "rdapConformance": [
         "rdap_openidc_remote_level_0"
       ],
       "lang": "en-US",
       "notices": {
         "title": "Login Result",
         "description": [
           "Login succeeded",
           "user.idp.example"
         ],
       },
       "session": {
         "userClaims": {
           "sub": "103892603076825016132",
           "name": "User Person",
           "given_name": "User",
           "family_name": "Person",
           "picture": "https://lh3.example.com/a-/AOh14=s96-c",
           "email": "user@example.com",
           "email_verified": true,
           "locale": "en",
           "purpose": "domainNameControl",
           "dnt": false
         },
         "sessionInfo": {
           "tokenExpiration": 3599,
           "tokenRefresh": true
         }
       }
     }

                                  Figure 3

   An example of a failed "session/login" response:

     {
       "rdapConformance": [
         "rdap_openidc_remote_level_0"
       ],
       "lang": "en-US",
       "notices": {
         "title": "Login Result",
         "description": [
           "Login failed",
           "user.idp.example"
           ]
       }
     }

                                  Figure 4

4.2.1.  Clients with Limited User Interfaces

   The "OAuth 2.0 Device Authorization Grant" [RFC8628] provides an
   OPTIONAL method to request user authorization from devices that have
   an Internet connection, but lack a suitable browser for a more
   traditional OAuth flow.  This method requires an End-User to use a
   second device (such as a smart telephone) that has access to a web
   browser for entry of a code sequence that is presented on the UI-
   constrained device.

4.2.1.1.  UI-constrained Client Login

   Client authentication is requested by sending a "session/device"
   request to an RDAP server.  If the RDAP server supports only remote
   Authorization Servers, the "session/device" request MUST include an
   End-User identifier that's delivered using one of two methods: by
   adding a query component to an RDAP request URI using the syntax
   described in Section 3.4 of RFC 3986 [RFC3986], or by including an
   HTTP authorization header for the Basic authentication scheme as
   described in RFC 7617 [RFC7617].  If the RDAP server supports a local
   Authorization Server, the End-User identifier MAY be omitted.
   Clients can use either of these methods.  Servers MUST support both
   methods.

   The query used to request client authentication is represented as an
   OPTIONAL "key=value" pair using a key value of "id" and a value
   component that contains the client identifier issued by an OP.

   An example using wget for client identifier "user.idp.example":

      wget -qO- --keep-session-cookies --save-
   cookies\https://example.com/rdap/session/device?id=user.idp.example --save-cookies\
      https://example.com/rdap/session/device?id=user.idp.example
                                  Figure 5

   The authorization header for the Basic authentication scheme contains
   a Base64-encoded representation of the client identifier issued by an
   OP.  No password is provided.

   An example using curl and an authorization header:

      curl -H "Authorization: Bearer dXNlci5pZHAuZXhhbXBsZQ=="\-c dXNlci5pZHAuZXhhbXBsZQ=="\
      -c cookies.txt https://example.com/rdap/session/device

                                  Figure 6

   The response to this request MUST use the response structures
   specified in RFC 9083 [RFC9083].  In addition, the response MUST
   include an indication of the requested operation's success or failure
   in the "notices" data structure (including the client identifier),
   and, if successful, a "deviceInfo" data structure.

   An example of a "session/device" response:

     {
       "rdapConformance": [
         "rdap_openidc_remote_level_0"
       ],
       "lang": "en-US",
       "notices": {
         "title": "Device Login Result",
         "description": [
           "Login succeeded",
           "user.idp.example"
         ]
       },
       "deviceInfo": {
         "verification_url": "https://www.example.com/device",
         "user_code": "NJJQ-GJFC",
         "expires_in": "1800" 1800
       }
     }

                                  Figure 5 7

4.2.1.2.  UI-constrained Client Login Polling

   After successful processing of the "session/device" request, the
   client MUST send a "session/devicepoll" request to the RDAP server to
   continue the login process.  This request performs the polling
   function described in RFC 8628 [RFC8628], allowing the RDAP server to
   wait for the End-User to enter the information returned from the
   "session/device" request using the interface on their second device.
   After the End-User has completed that process, or if the process
   fails or times out, the OP will respond to the polling requests with
   an indication of success or failure.

   An example using wget:

      wget -qO- --load-cookies
   cookies.txt\https://example.com/rdap/session/devicepoll cookies.txt\
      https://example.com/rdap/session/devicepoll

                                  Figure 8

   An example using curl:

      curl -b cookies.txt https://example.com/rdap/session/devicepoll

                                  Figure 9

   The response to this request MUST use the response structures
   described in Section 4.2.  RDAP query processing can continue
   normally on the UI-constrained device once the "login" process has
   been completed.

4.3.  Session Status

   Clients MAY send a query to an RDAP server to determine the status of
   an existing login session using a "session/status" path segment.  An
   example "session/status" request:

   https://example.com/rdap/session/status

   The response to this query MUST use the response structures specified
   in RFC 9083 [RFC9083].  In addition, the response MUST include an
   indication of the requested operation's success or failure in the
   "notices" data structure (including the client identifier), and, if
   successful, a "session" data structure.

   An example of a "session/status" response:

     {
       "rdapConformance": [
         "rdap_openidc_remote_level_0"
       ],
       "lang": "en-US",
       "notices": {
         "title": "Session Status Result",
         "description": [
           "Session status succeeded",
           "user.idp.example"
         ]
       },
       "session": {
         "userClaims": {
           "sub": "103892603076825016132",
           "name": "User Person",
           "given_name": "User",
           "family_name": "Person",
           "picture": "https://lh3.example.com/a-/AOh14=s96-c",
           "email": "user@example.com",
           "email_verified": true,
           "locale": "en",
           "purpose": "domainNameControl",
           "dnt": false
         },
         "sessionInfo": {
           "tokenExpiration": 3490,
           "tokenRefresh": true
         }
       }
     }

                                 Figure 6 10

4.4.  Session Refresh

   Clients MAY send a request to an RDAP server to refresh, or extend,
   an existing login session using a "session/refresh" path segment.
   The RDAP server MAY attempt to refresh the access token associated
   with the current session as part of extending the session for a
   period of time determined by the RDAP server.  As described in RFC
   6749 [RFC6749], OP support for refresh tokens is OPTIONAL.  An RDAP
   server MUST determine if the OP supports token refresh and process
   the refresh request by either requesting refresh of the access token
   or by returning a response that indicates that token refresh is not
   supported by the OP in the "notices" data structure.  An example
   "session/refresh" request:

   https://example.com/rdap/session/refresh

   The response to this request MUST use the response structures
   specified in RFC 9083 [RFC9083].  In addition, the response MUST
   include an indication of the requested operation's success or failure
   in the "notices" data structure (including the client identifier),
   and, if successful, a "session" data structure.

   An example of a "session/refresh" response:

     {
       "rdapConformance": [
         "rdap_openidc_remote_level_0"
       ],
       "lang": "en-US",
       "notices": {
         "title": "Session Refresh Result",
         "description": [
           "Session refresh succeeded",
           "user.idp.example",
           "Token refresh succeeded."
         ]
       },
       "session": {
         "userClaims": {
           "sub": "103892603076825016132",
           "name": "User Person",
           "given_name": "User",
           "family_name": "Person",
           "picture": "https://lh3.example.com/a-/AOh14=s96-c",
           "email": "user@example.com",
           "email_verified": true,
           "locale": "en",
           "purpose": "domainNameControl",
           "dnt": false
         },
         "sessionInfo": {
           "tokenExpiration": 3599,
           "tokenRefresh": true
         }
       }
     }

                                 Figure 7 11

4.5.  Client Logout

   Clients MAY send a request to an RDAP server to terminate an existing
   login session.  Termination of a session is requested using a
   "session/logout" path segment.  Access and refresh tokens can be
   revoked during the "session/logout" process as described in RFC 7009
   [RFC7009] if supported by the OP (token revocation endpoint support
   is OPTIONAL per RFC 8414 [RFC8414]).  If supported, this feature
   SHOULD be used to ensure that the tokens are not mistakenly
   associated with a future RDAP session.  Alternatively, an RDAP server
   MAY attempt to logout from the OP using the "OpenID Connect RP-
   Initiated Logout" protocol ([OIDCL]) if that protocol is supported by
   the OP.

   An example "session/logout" request:

   https://example.com/rdap/session/logout

   The response to this request MUST use the response structures
   specified in RFC 9083 [RFC9083].  In addition, the response MUST
   include an indication of the requested operation's success or failure
   in the "notices" data structure (including the client identifier).
   The "notices" data structure MUST also include an indication of the
   success or failure of any attempt to logout from the OP or to revoke
   the tokens issued by the OP.

   An example of a "session/logout" response:

     {
       "rdapConformance": [
         "rdap_openidc_remote_level_0"
       ],
       "lang": "en-US",
       "notices": {
         "title": "Logout Result",
         "description": [
           "Logout succeeded",
           "user.idp.example",
           "Provider logout failed: Not supported by provider.",
           "Token revocation successful."
         ]
       }
     }

                                 Figure 8 12

   In the absence of a "logout" request, an RDAP session MUST be
   terminated by the RDAP server after a server-defined period of time.
   The server should also take appropriate steps to ensure that the
   tokens associated with the terminated session cannot be reused.  This
   SHOULD include revoking the tokens or logging out from the OP if
   either operation is supported by the OP.

4.6.  Parameter Processing

   Unrecognized query parameters MUST be ignored.  An RDAP server that
   processes an authenticated query MUST determine if the End-User
   identification information is associated with an OP that is
   recognized and supported by the server.  Servers MUST reject queries
   that include identification information that is not associated with a
   supported OP by returning an HTTP 501 (Not Implemented) response.  An
   RDAP server that receives a query containing identification
   information associated with a recognized OP MUST perform the steps
   required to authenticate the user with the OP, process the query, and
   return an RDAP response that is appropriate for the End-User's level
   of authorization and access.

5.  Token Exchange

   ID tokens include an audience parameter that contains the OAuth 2.0
   client_id of the RP as an audience value.  In some operational
   scenarios (such as a client that is providing a proxy service), an RP
   can receive tokens with an audience value that does not include the
   RP's client_id.  These tokens might not be trusted by the RP, and the
   RP might refuse to accept the tokens.  This situation can be remedied
   by having the RP exchange these tokens with the OP for a set of
   trusted tokens that reset the audience parameter.  This token
   exchange protocol is described in RFC 8693 [RFC8693].  This issue is
   not visible to the RDAP client and should be managed by the OpenID
   implementation used by the RDAP server.

6.  RDAP Query Processing

   Once an RDAP session is active, an RDAP server MUST determine if the
   End-User is authorized to perform any queries that are received
   during the duration of the session.  This MAY include rejecting
   queries outright, and it MAY include omitting or otherwise redacting
   information that the End-User is not authorized to receive.  Specific
   processing requirements are beyond the scope of this document.  A
   client can end a session explicitly by sending a "session/logout"
   request to the RDAP server.  A session can also be ended implicitly
   by the server after a server-defined period of time.  The status of a
   session can be determined at any time by sending a "session/status"
   query to the RDAP server.

   An RDAP server MUST maintain session state information for the
   duration of an active session.  This is commonly done using HTTP
   cookies as described in RFC 6265 [RFC6265].  Doing so allows End-User
   to submit queries without having to explicitly identify and
   authenticate themselves for each and every query.

7.  RDAP Conformance

   RDAP responses that contain values described in this document MUST
   indicate conformance with this specification by including an
   rdapConformance ([RFC9083]) value of "rdap_openidc_remote_level_0"
   (to indicate support for one or more remote Authorization Servers),
   "rdap_openidc_local_level_0" (to indicate support for a local
   Authorization Server), or both values if the server supports both
   remote and local OpenID Authorization Servers.  The information
   needed to register these values in the RDAP Extensions Registry is
   described in Section 8.1.

   Example rdapConformance structure with extension specified:

      "rdapConformance" :
        [
          "rdap_level_0",
          "rdap_openidc_remote_level_0"
        ]

                                 Figure 9 13

8.  IANA Considerations

8.1.  RDAP Extensions Registry

   IANA is requested to register the following values in the RDAP
   Extensions Registry:

   *

      Extension identifier: rdap_openidc_remote_level_0
   *
      Registry operator: Any
   *
      Published specification: This document.
   *
      Contact: IESG <iesg@ietf.org>
   *
      Intended usage: This extension describes a federated
      authentication method for RDAP using OAuth 2.0, OpenID Connect,
      and a remote Authorization Server.

   *

      Extension identifier: rdap_openidc_local_level_0
   *
      Registry operator: Any
   *
      Published specification: This document.
   *
      Contact: IESG <iesg@ietf.org>
   *
      Intended usage: This extension describes a federated
      authentication method for RDAP using OAuth 2.0, OpenID Connect,
      and a local Authorization Server.

8.2.  JSON Web Token Claims Registry

   IANA is requested to register the following values in the JSON Web
   Token Claims Registry:

   *

      Claim Name: "purpose"
   *
      Claim Description: This claim describes the stated purpose for
      submitting a request to access a protected RDAP resource.
   *
      Change Controller: IESG
   *
      Specification Document(s): Section 3.1.4.1 of this document.

   *

      Claim Name: "dnt"
   *
      Claim Description: This claim contains a JSON boolean literal that
      describes an End-User's "do not track" preference for identity
      tracking, logging, or recording when accessing a protected RDAP
      resource.
   *
      Change Controller: IESG
   *
      Specification Document(s): Section 3.1.4.2 of this document.

8.3.  RDAP Query Purpose Registry

   IANA is requested to create a new protocol registry to manage RDAP
   query purpose values.  This registry should be named "Registration
   Data Access Protocol (RDAP) Query Purpose Values" and should appear
   under its own
   heading on IANA's protocol listings, using the same title as the name "Registration Data Access Protocol (RDAP)" section of the registry.
   IANA's protocol registries.  The information to be registered and the
   procedures to be followed in populating the registry are described in
   Section 3.1.4.1.

   Name of registry: Registration Data Access Protocol (RDAP) Query
   Purpose Values

   Section at http://www.iana.org/protocols:

   Registry Title: Registration Data Access
   Protocol (RDAP) Query
   Purpose Values

   Registry Name:

   Name of registry: Registration Data Access Protocol (RDAP) Query
   Purpose Values

   Registration Procedure: Specification Required

   Reference: This draft document

   Required information: See Section 3.1.4.1.

   Review process: "Specification Required" as described in RFC 5226
   [RFC5226].

   Size, format, and syntax of registry entries: See Section 3.1.4.1.

   Initial assignments and reservations:

   -----BEGIN FORM-----

      Value: domainNameControl

      Description: Tasks within the scope of this purpose include
      creating and managing and monitoring a registrant's own domain
      name, including creating the domain name, updating information
      about the domain name, transferring the domain name, renewing the
      domain name, deleting the domain name, maintaining a domain name
      portfolio, and detecting fraudulent use of the Registrant's own
      contact information.

   -----END FORM-----

   -----BEGIN FORM-----

      Value: personalDataProtection

      Description: Tasks within the scope of this purpose include
      identifying the accredited privacy/proxy provider associated with
      a domain name and reporting abuse, requesting reveal, or otherwise
      contacting the provider.

   -----END FORM-----

   -----BEGIN FORM-----

      Value: technicalIssueResolution

      Description: Tasks within the scope of this purpose include (but
      are not limited to) working to resolve technical issues, including
      email delivery issues, DNS resolution failures, and web site
      functional issues.

   -----END FORM-----

   -----BEGIN FORM-----

      Value: domainNameCertification

      Description: Tasks within the scope of this purpose include a
      Certification Authority (CA) issuing an X.509 certificate to a
      subject identified by a domain name.

   -----END FORM-----

   -----BEGIN FORM-----

      Value: individualInternetUse

      Description: Tasks within the scope of this purpose include
      identifying the organization using a domain name to instill
      consumer trust, or contacting that organization to raise a
      customer complaint to them or file a complaint about them.

   -----END FORM-----

   -----BEGIN FORM-----

      Value: businessDomainNamePurchaseOrSale

      Description: Tasks within the scope of this purpose include making
      purchase queries about a domain name, acquiring a domain name from
      a registrant, and enabling due diligence research.

   -----END FORM-----

   -----BEGIN FORM-----

      Value: academicPublicInterestDNSRResearch

      Description: Tasks within the scope of this purpose include
      academic public interest research studies about domain names
      published in the registration data service, including public
      information about the registrant and designated contacts, the
      domain name's history and status, and domain names registered by a
      given registrant (reverse query).

   -----END FORM-----

   -----BEGIN FORM-----

      Value: legalActions

      Description: Tasks within the scope of this purpose include
      investigating possible fraudulent use of a registrant's name or
      address by other domain names, investigating possible trademark
      infringement, contacting a registrant/licensee's legal
      representative prior to taking legal action and then taking a
      legal action if the concern is not satisfactorily addressed.

   -----END FORM-----
   -----BEGIN FORM-----

      Value: regulatoryAndContractEnforcement

      Description: Tasks within the scope of this purpose include tax
      authority investigation of businesses with online presence,
      Uniform Dispute Resolution Policy (UDRP) investigation,
      contractual compliance investigation, and registration data escrow
      audits.

   -----END FORM-----

   -----BEGIN FORM-----

      Value: criminalInvestigationAndDNSAbuseMitigation

      Description: Tasks within the scope of this purpose include
      reporting abuse to someone who can investigate and address that
      abuse, or contacting entities associated with a domain name during
      an offline criminal investigation.

   -----END FORM-----

   -----BEGIN FORM-----

      Value: dnsTransparency

      Description: Tasks within the scope of this purpose involve
      querying the registration data made public by registrants to
      satisfy a wide variety of use cases around informing the general
      public.

   -----END FORM-----

9.  Implementation Status

   NOTE: Please remove this section and the reference to RFC 7942 prior
   to publication as an RFC.

   This section records the status of known implementations of the
   protocol defined by this specification at the time of posting of this
   Internet-Draft, and is based on a proposal described in RFC 7942
   [RFC7942].  The description of implementations in this section is
   intended to assist the IETF in its decision processes in progressing
   drafts to RFCs.  Please note that the listing of any individual
   implementation here does not imply endorsement by the IETF.
   Furthermore, no effort has been spent to verify the information
   presented here that was supplied by IETF contributors.  This is not
   intended as, and must not be construed to be, a catalog of available
   implementations or their features.  Readers are advised to note that
   other implementations may exist.

   According to RFC 7942, "this will allow reviewers and working groups
   to assign due consideration to documents that have the benefit of
   running code, which may serve as evidence of valuable experimentation
   and feedback that have made the implemented protocols more mature.
   It is up to the individual working groups to use this information as
   they see fit".

   Version -09 of this specification introduced changes that are
   incompatible with earlier implementations.  Implementations that are
   consistent with this specification will be added as they are
   identified.

9.1.  Editor Implementation

   *

      Location: https://procuratus.net/rdap/
   *
      Description: This implementation is a functionally-limited RDAP
      server that supports only the path segments described in this
      specification.  It uses the "jumbojett/OpenID-Connect-PHP" library
      found on GitHub, which appears to no longer be under active
      development.  The library was modified to add support for the
      device authorization grant.  Session variable management is still
      a little buggy.  Supported OPs include Google (Gmail) and Yahoo.
   *
      Level of Maturity: This is a "proof of concept" research
      implementation.
   *
      Coverage: This implementation includes all of the features
      described in this specification.
   *
      Version compatibility: Version -11 -11+ of this specification.
   *
      Contact Information: Scott Hollenbeck, shollenbeck@verisign.com

9.2.  Verisign Labs

   *

      Responsible Organization: Verisign Labs
   *
      Location: https://rdap.verisignlabs.com/
   *
      Description: This implementation includes support for domain
      registry RDAP queries using live data from the .cc and .tv country
      code top-level domains and the .career generic top-level domain.
      Three access levels are provided based on the authenticated
      identity of the client:
      1.  Unauthenticated: Limited information is returned in response
          to queries from unauthenticated clients.

      2.  Basic: Clients who authenticate using a publicly available
          identity provider like Google Gmail or Microsoft Hotmail will
          receive all of the information available to an unauthenticated
          client plus additional registration metadata, but no
          personally identifiable information associated with entities.
      3.  Advanced: Clients who authenticate using a more restrictive
          identity provider will receive all of the information
          available to a Basic client plus whatever information the
          server operator deems appropriate for a fully authorized
          client.  Currently supported identity providers include those
          developed by Verisign Labs
          (https://testprovider.rdap.verisignlabs.com/) and CZ.NIC
          (https://www.mojeid.cz/).
   *
      Level of Maturity: This is a "proof of concept" research
      implementation.
   *
      Coverage: This implementation includes all of the features
      described in this specification.
   *
      Version compatibility: Version -07 of this specification.
   *
      Contact Information: Scott Hollenbeck, shollenbeck@verisign.com

9.3.  Viagenie

   *

      Responsible Organization: Viagenie
   *
      Location: https://auth.viagenie.ca
   *
      Description: This implementation is an OpenID identity provider
      enabling users and registries to connect to the federation.  It
      also includes a barebone RDAP client and RDAP server in order to
      test the authentication framework.  Various level of purposes are
      available for testing.
   *
      Level of Maturity: This is a "proof of concept" research
      implementation.
   *
      Coverage: This implementation includes most features described in
      this specification as an identity provider.
   *
      Version compatibility: Version -07 of this specification.
   *
      Contact Information: Marc Blanchet, marc.blanchet@viagenie.ca

10.  Security Considerations

   Security considerations for RDAP can be found in RFC 7481 [RFC7481].
   Security considerations for OpenID Connect Core [OIDCC] and OAuth 2.0
   [RFC6749] can be found in their reference specifications.  OpenID
   Connect defines optional mechanisms for robust signing and encryption
   that can be used to provide data integrity and data confidentiality
   services as needed.

10.1.  Authentication and Access Control

   Having completed the client identification, authorization, and
   validation process, an RDAP server can make access control decisions
   based on a comparison of client-provided information and local
   policy.  For example, a client who provides an email address (and
   nothing more) might be entitled to receive a subset of the
   information that would be available to a client who provides an email
   address, a full name, and a stated purpose.  Development of these
   access control policies is beyond the scope of this document.

11.  Acknowledgments

   The author would like to acknowledge the following individuals for
   their contributions to the development of this document: Marc
   Blanchet, Tom Harrison, Russ Housley, Jasdip Singh, Rhys Smith,
   Jaromir Talir, Rick Wilhelm, and Alessandro Vesely.  In addition, the
   Verisign Registry Services Lab development team of Joseph Harvey,
   Andrew Kaizer, Sai Mogali, Anurag Saxena, Swapneel Sheth, Nitin
   Singh, and Zhao Zhao provided critical "proof of concept"
   implementation experience that helped demonstrate the validity of the
   concepts described in this document.

   Mario Loffredo provided significant feedback based on implementation
   experience that led to welcome improvements in several sections of
   this document.  His contributions are greatly appreciated.

12.  References

12.1.  Normative References

   [OIDC]     OpenID Foundation, "OpenID Connect",
              <http://openid.net/connect/>.

   [OIDCC]    OpenID Foundation, "OpenID Connect Core incorporating
              errata set 1", November 2014,
              <http://openid.net/specs/openid-connect-core-1_0.html>.

   [OIDCD]    OpenID Foundation, "OpenID Connect Discovery 1.0
              incorporating errata set 1", November 2014,
              <http://openid.net/specs/openid-connect-discovery-
              1_0.html>.

   [OIDCL]    OpenID Foundation, "OpenID Connect RP-Initiated Logout 1.0
              - draft 01", August 2020, <https://openid.net/specs/
              openid-connect-rpinitiated-1_0.html>.

   [OIDCR]    OpenID Foundation, "OpenID Connect Dynamic Client
              Registration 1.0 incorporating errata set 1", November
              2014, <http://openid.net/specs/openid-connect-
              registration-1_0.html>.

   [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>.

   [RFC3986]  Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
              Resource Identifier (URI): Generic Syntax", STD 66,
              RFC 3986, DOI 10.17487/RFC3986, January 2005,
              <https://www.rfc-editor.org/info/rfc3986>.

   [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", RFC 5226,
              DOI 10.17487/RFC5226, May 2008,
              <https://www.rfc-editor.org/info/rfc5226>.

   [RFC6265]  Barth, A., "HTTP State Management Mechanism", RFC 6265,
              DOI 10.17487/RFC6265, April 2011,
              <https://www.rfc-editor.org/info/rfc6265>.

   [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>.

   [RFC7009]  Lodderstedt, T., Ed., Dronia, S., and M. Scurtescu, "OAuth
              2.0 Token Revocation", RFC 7009, DOI 10.17487/RFC7009,
              August 2013, <https://www.rfc-editor.org/info/rfc7009>.

   [RFC7230]  Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
              Protocol (HTTP/1.1): Message Syntax and Routing",
              RFC 7230, DOI 10.17487/RFC7230, June 2014,
              <https://www.rfc-editor.org/info/rfc7230>.

   [RFC7480]  Newton, A., Ellacott, B., and N. Kong, "HTTP Usage in the
              Registration Data Access Protocol (RDAP)", STD 95,
              RFC 7480, DOI 10.17487/RFC7480, March 2015,
              <https://www.rfc-editor.org/info/rfc7480>.

   [RFC7481]  Hollenbeck, S. and N. Kong, "Security Services for the
              Registration Data Access Protocol (RDAP)", STD 95,
              RFC 7481, DOI 10.17487/RFC7481, March 2015,
              <https://www.rfc-editor.org/info/rfc7481>.

   [RFC7519]  Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token
              (JWT)", RFC 7519, DOI 10.17487/RFC7519, May 2015,
              <https://www.rfc-editor.org/info/rfc7519>.

   [RFC7617]  Reschke, J., "The 'Basic' HTTP Authentication Scheme",
              RFC 7617, DOI 10.17487/RFC7617, September 2015,
              <https://www.rfc-editor.org/info/rfc7617>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

   [RFC8628]  Denniss, W., Bradley, J., Jones, M., and H. Tschofenig,
              "OAuth 2.0 Device Authorization Grant", RFC 8628,
              DOI 10.17487/RFC8628, August 2019,
              <https://www.rfc-editor.org/info/rfc8628>.

   [RFC8693]  Jones, M., Nadalin, A., Campbell, B., Ed., Bradley, J.,
              and C. Mortimore, "OAuth 2.0 Token Exchange", RFC 8693,
              DOI 10.17487/RFC8693, January 2020,
              <https://www.rfc-editor.org/info/rfc8693>.

   [RFC9082]  Hollenbeck, S. and A. Newton, "Registration Data Access
              Protocol (RDAP) Query Format", STD 95, RFC 9082,
              DOI 10.17487/RFC9082, June 2021,
              <https://www.rfc-editor.org/info/rfc9082>.

   [RFC9083]  Hollenbeck, S. and A. Newton, "JSON Responses for the
              Registration Data Access Protocol (RDAP)", STD 95,
              RFC 9083, DOI 10.17487/RFC9083, June 2021,
              <https://www.rfc-editor.org/info/rfc9083>.

12.2.  Informative References

   [RFC4949]  Shirey, R., "Internet Security Glossary, Version 2",
              FYI 36, RFC 4949, DOI 10.17487/RFC4949, August 2007,
              <https://www.rfc-editor.org/info/rfc4949>.

   [RFC7942]  Sheffer, Y. and A. Farrel, "Improving Awareness of Running
              Code: The Implementation Status Section", BCP 205,
              RFC 7942, DOI 10.17487/RFC7942, July 2016,
              <https://www.rfc-editor.org/info/rfc7942>.

   [RFC8414]  Jones, M., Sakimura, N., and J. Bradley, "OAuth 2.0
              Authorization Server Metadata", RFC 8414,
              DOI 10.17487/RFC8414, June 2018,
              <https://www.rfc-editor.org/info/rfc8414>.

Appendix A.  Change Log

   00:  Initial working group version ported from draft-hollenbeck-
      regext-rdap-openid-10.
   01:  Modified ID Token delivery approach to note proper use of an
      HTTP bearer authorization header.
   02:  Modified token delivery approach (Access Token is the bearer
      token) to note proper use of an HTTP bearer authorization header,
      fixing the change made in -01.
   03:  Updated OAuth 2.0 Device Authorization Grant description and
      reference due to publication of RFC 8628.
   04:  Updated OAuth 2.0 token exchange description and reference due
      to publication of RFC 8693.  Corrected the RDAP conformance
      identifier to be registered with IANA.
   05:  Keepalive refresh.
   06:  Keepalive refresh.
   07:  Added "login_hint" description to Section 3.1.3.2.  Added some
      text to Section 3.1.4.2 to note that "do not track" requires
      compliance with local regulations.
   08:  Rework of token management processing in Sections 4 and 5.
   09:  Updated RDAP specification references.  Added text to describe
      both local and remote Authorization Server processing.  Removed
      text that described passing of ID Tokens as query parameters.
   10:  Updated Section 3.1.3.1.  Replaced token processing queries with
      "login", "session", and "logout" queries.
   11:  Replaced queries with "session/*" queries.  Added description of
      "rdap" OAuth scope.  Added implementation status information.
   12:  Updated data structure descriptions.  Updated Section 8.  Minor
      formatting changes due to a move to xml2rfc-v3 markup.

Author's Address

   Scott Hollenbeck
   Verisign Labs
   12061 Bluemont Way
   Reston, VA 20190
   United States of America
   Email: shollenbeck@verisign.com
   URI:   http://www.verisignlabs.com/