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Federated Authentication for the Registration Data Access Protocol (RDAP) using OpenID Connect
draft-ietf-regext-rdap-openid-27

Document Type Active Internet-Draft (regext WG)
Author Scott Hollenbeck
Last updated 2023-11-13 (Latest revision 2023-11-05)
Replaces draft-hollenbeck-regext-rdap-openid
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Submit for publication "Federated Authentication for the Registration Data Access Protocol (RDAP) using OpenID Connect"
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Details
draft-ietf-regext-rdap-openid-27
REGEXT Working Group                                       S. Hollenbeck
Internet-Draft                                             Verisign Labs
Intended status: Standards Track                         5 November 2023
Expires: 8 May 2024

   Federated Authentication for the Registration Data Access Protocol
                      (RDAP) using OpenID Connect
                    draft-ietf-regext-rdap-openid-27

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

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

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on 8 May 2024.

Copyright Notice

   Copyright (c) 2023 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents (https://trustee.ietf.org/
   license-info) in effect on the date of publication of this document.
   Please review these documents carefully, as they describe your rights
   and restrictions with respect to this document.  Code Components
   extracted from this document must include Revised BSD License text as
   described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Problem Statement . . . . . . . . . . . . . . . . . . . .   4
     1.2.  Approach  . . . . . . . . . . . . . . . . . . . . . . . .   4
   2.  Conventions Used in This Document . . . . . . . . . . . . . .   4
   3.  Federated Authentication for RDAP . . . . . . . . . . . . . .   5
     3.1.  RDAP and OpenID Connect . . . . . . . . . . . . . . . . .   5
       3.1.1.  Terminology . . . . . . . . . . . . . . . . . . . . .   6
       3.1.2.  Client Considerations . . . . . . . . . . . . . . . .   7
       3.1.3.  Overview  . . . . . . . . . . . . . . . . . . . . . .   7
       3.1.4.  RDAP Authentication and Authorization Steps . . . . .  12
         3.1.4.1.  Provider Discovery  . . . . . . . . . . . . . . .  12
         3.1.4.2.  Authentication Request  . . . . . . . . . . . . .  12
         3.1.4.3.  End-User Authorization  . . . . . . . . . . . . .  13
         3.1.4.4.  Authorization Response and Validation . . . . . .  13
         3.1.4.5.  Token Processing  . . . . . . . . . . . . . . . .  14
         3.1.4.6.  Delivery of User Information  . . . . . . . . . .  14
       3.1.5.  Specialized Claims and Authorization Scope for
               RDAP  . . . . . . . . . . . . . . . . . . . . . . . .  14
         3.1.5.1.  Stated Purposes . . . . . . . . . . . . . . . . .  14
         3.1.5.2.  Do Not Track  . . . . . . . . . . . . . . . . . .  15
   4.  Common Protocol Features  . . . . . . . . . . . . . . . . . .  16
     4.1.  OpenID Connect Configuration  . . . . . . . . . . . . . .  16
     4.2.  RDAP Query Parameters . . . . . . . . . . . . . . . . . .  18
       4.2.1.  RDAP Query Purpose  . . . . . . . . . . . . . . . . .  19
       4.2.2.  RDAP Do Not Track . . . . . . . . . . . . . . . . . .  19
       4.2.3.  Parameter Processing  . . . . . . . . . . . . . . . .  19
   5.  Protocol Features for Session-Oriented Clients  . . . . . . .  20
     5.1.  Data Structures . . . . . . . . . . . . . . . . . . . . .  20
       5.1.1.  Session . . . . . . . . . . . . . . . . . . . . . . .  20
       5.1.2.  Device Info . . . . . . . . . . . . . . . . . . . . .  21
     5.2.  Client Login  . . . . . . . . . . . . . . . . . . . . . .  22
       5.2.1.  End-User Identifier . . . . . . . . . . . . . . . . .  23
       5.2.2.  OP Issuer Identifier  . . . . . . . . . . . . . . . .  23
       5.2.3.  Login Response  . . . . . . . . . . . . . . . . . . .  24
       5.2.4.  Clients with Limited User Interfaces  . . . . . . . .  26
         5.2.4.1.  UI-constrained Client Login . . . . . . . . . . .  26
         5.2.4.2.  UI-constrained Client Login Polling . . . . . . .  28

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     5.3.  Session Status  . . . . . . . . . . . . . . . . . . . . .  29
     5.4.  Session Refresh . . . . . . . . . . . . . . . . . . . . .  31
     5.5.  Client Logout . . . . . . . . . . . . . . . . . . . . . .  33
     5.6.  Request Sequencing  . . . . . . . . . . . . . . . . . . .  34
   6.  Protocol Features for Token-Oriented Clients  . . . . . . . .  35
     6.1.  Client Login  . . . . . . . . . . . . . . . . . . . . . .  35
     6.2.  Client Queries  . . . . . . . . . . . . . . . . . . . . .  36
     6.3.  Access Token Validation . . . . . . . . . . . . . . . . .  36
     6.4.  Token Exchange  . . . . . . . . . . . . . . . . . . . . .  36
   7.  RDAP Query Processing . . . . . . . . . . . . . . . . . . . .  37
   8.  RDAP Conformance  . . . . . . . . . . . . . . . . . . . . . .  37
   9.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  37
     9.1.  RDAP Extensions Registry  . . . . . . . . . . . . . . . .  37
     9.2.  JSON Web Token Claims Registry  . . . . . . . . . . . . .  37
     9.3.  RDAP Query Purpose Registry . . . . . . . . . . . . . . .  38
   10. Implementation Status . . . . . . . . . . . . . . . . . . . .  41
     10.1.  Editor Implementation  . . . . . . . . . . . . . . . . .  42
     10.2.  Verisign Labs  . . . . . . . . . . . . . . . . . . . . .  42
     10.3.  Viagenie . . . . . . . . . . . . . . . . . . . . . . . .  43
   11. Security Considerations . . . . . . . . . . . . . . . . . . .  44
     11.1.  Authentication and Access Control  . . . . . . . . . . .  44
   12. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  45
   13. References  . . . . . . . . . . . . . . . . . . . . . . . . .  45
     13.1.  Normative References . . . . . . . . . . . . . . . . . .  45
     13.2.  Informative References . . . . . . . . . . . . . . . . .  47
   Appendix A.  Change Log . . . . . . . . . . . . . . . . . . . . .  48
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  50

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) [RFC9110].

   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.

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1.1.  Problem Statement

   The conventional "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.  Approach

   A basic level of RDAP service can be provided to users who possess an
   identifier issued by a recognized provider who can 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 themselves 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 identity
   provider would make it easier to operate and use RDAP by reusing
   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 RDAP server
   operator with the consent of the user in order to help the server
   operator make access control decisions.  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 identity provider.  This
   document describes a federated authentication system for RDAP based
   on OpenID Connect [OIDC] that meets 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.

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   All of the HTTP requests described in this document that are sent
   from an RDAP client to an RDAP server use the HTTP GET method as
   specified in [RFC9110].

   Long lines in examples are wrapped using the "The Single Backslash
   Strategy" described in RFC 8792 [RFC8792].

3.  Federated Authentication for RDAP

   RDAP itself does not include built-in 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 conventional 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.

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   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 OpenID
   Providers 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" as defined by RDAP
   [RFC7480].

   This document uses the terms "Access Token", "Authorization Code",
   "Authorization Endpoint", "Authorization Grant", "Client
   Authentication", "Client Identifier", "Protected Resource", "Refresh
   Token", "Resource Owner", "Resource Server", and "Token Endpoint"
   defined by OAuth 2.0 [RFC6749]; the terms "Claim Name", "Claim
   Value", and "JSON Web Token (JWT)" defined by JSON Web Token (JWT)
   [RFC7519]; the terms "ID Token" and "UserInfo Endpoint" defined by
   OpenID Connect Core 1.0 [OIDCC]; and the term "JWT Access Token"
   defined by RFC 9068 [RFC9068].  Additional terms from Section 1.2 of
   the OpenID Connect Core specification are incorporated by reference.

   This document uses the terms "remote" and "default" to describe the
   relationship between an RDAP server and the OpenID Providers that it
   interacts with.  A "remote" OpenID Provider is one that is identified
   by the RDAP Client by providing either an Issuer Identifier or an
   End-User Identifier in a login request.  Whether an Issuer Identifier
   or End-User Identifier can be provided in the login request for the
   purposes of selecting an OpenID Provider can be determined by
   retrieving the RDAP Server's OIDC configuration details (see
   Section 4.1).  A "default" OpenID Provider is one that the RDAP
   Server will use when the RDAP Client does not provide an Issuer
   Identifier or an End-User Identifier in the login request.

   This document uses the term "session" to describe a set of
   interactions between an RDAP client and an RDAP server during a given
   period of time.  For session-oriented clients (see Section 3.1.2),
   the RDAP session is a typical HTTP session starting with a
   farv1_session/login request and ending with either a farv1_session/
   logout request (see Section 5 for a description of both path
   segments) or a timeout.  For token-oriented clients (see
   Section 3.1.2 and Section 6), the RDAP session corresponds to the
   lifespan of an authorization obtained from an OP and the
   corresponding Access Token, including any refreshed Access Token.

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3.1.2.  Client Considerations

   Clients that delegate OIDC Authentication to an RDAP server as part
   of session-oriented interactions, and can accept and process HTTP
   cookies [RFC6265] to maintain the session, are known as "session-
   oriented" clients.  This type of RDAP client performs the role of
   user agent [RFC9110].  An RDAP server performs the role of an OpenID
   Connect Core Relying Party (RP).  A web browser used to send queries
   directly to an RDAP server is an example of a session-oriented
   client.  Specifications for this type of client can be found in
   Section 5.

   Clients that perform OIDC Authentication directly, taking the role of
   an RP in interactions with an OP and sending Access Tokens [RFC6749]
   to an RDAP server to authorize RDAP queries, are known as "token-
   oriented" clients.  An RDAP server performs resource server [RFC6749]
   functions to verify the tokens received from the client, and RP
   functions to retrieve information from the OP as necessary to make
   access control decisions.  A web browser running JavaScript received
   from a web service that sends queries to an RDAP server directly or
   through its back-end web service is an example of a token-oriented
   client.  Specifications for this type of client can be found in
   Section 6.

   Clients MAY operate as either session-oriented or token-oriented
   clients, but they MUST do so consistently by not mixing token-
   oriented and session-oriented requests while interacting with an OP.
   Servers SHOULD support both types of client to maximize
   interoperability, but MAY choose to support only one type of client
   as required by local policy or operating conditions.  A server that
   does not support a particular client type will not support the
   protocol features (the data structures, path segments, parameters,
   and interactions) specified for that client type.  Server signaling
   of supported client types is described in Section 4.1.

3.1.3.  Overview

   At a high level, RDAP authentication of a session-oriented 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 and capabilities of the OpenID Providers that
        are used by the RDAP server.  This information is returned in
        the rdapConformance section of the response.  A value of "farv1"
        indicates support for the extension described in this
        specification.  If one or more remote OpenID Providers are
        supported, the RDAP client SHOULD evaluate the additional
        information described in Section 4.1 in order to discover the

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        capabilities of the RDAP server and optionally obtain the set of
        supported OPs unless that information is available from a
        trusted out-of-band source and has already been processed.
   2.   An RDAP client sends an RDAP "login" request to an RDAP server
        as described in Section 5.2.
   3.   The RDAP server prepares an Authentication Request containing
        the desired request parameters.
   4.   The RDAP server sends an Authentication Request to an OpenID
        Provider (OP) Authorization Endpoint and redirects the RDAP
        client to the OpenID Provider using an HTTP redirect.
   5.   The OpenID Provider authenticates the End-User.
   6.   The OpenID Provider obtains End-User consent/authorization.
   7.   The OpenID Provider sends the RDAP Client back to the RDAP
        server with an Authorization Code using an HTTP redirect.
   8.   The RDAP server requests tokens using the Authorization Code at
        the OpenID Provider's 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 tokens as described in [OIDCC] and
        retrieves the claims associated with the End-User's identity
        from the OpenID Provider's UserInfo Endpoint.

   The steps above can be described in a sequence diagram:

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   End          OpenID         RDAP                 RDAP
   User        Provider       Client               Server
     |             |             |                    |
     |             |             |-----Help Query---->|
     |             |             |                    |
     |             |             |<---Help Response---|
     |             |             |                    |
     |-------Login Request------>|                    |
     |             |             |                    |
     |             |             |---Login Request--->|
     |             |             |                    |
     |             |<-----Authentication Request------|
     |             |             |                    |
     | Credential--|             |                    |
     |<--Request   |             |                    |
     |             |             |                    |
     |--Credential |             |                    |
     |   Response->|             |                    |
     |             |             |                    |
     |             |-----Authentication Response----->|
     |             |             |                    |
     |             |<----------Token Request----------|
     |             |             |                    |
     |             |-----------Token Response-------->|
     |             |             |                    |
     |             |<----------Claim Request----------|
     |             |             |                    |
     |             |-----------Claim Response-------->|
     |             |             |                    |
     |             |             |<--Login Response---|
     |             |             |                    |
     |<------Login Response------|                    |
     |             |             |                    |
     |----------RDAP Query------>|                    |
     |             |             |                    |
     |             |             |-----RDAP Query---->|
     |             |             |                    |
     |             |             |<---RDAP Response---|
     |             |             |                    |
     |<------RDAP Response-------|                    |

                                  Figure 1

   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.

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   RDAP authentication of a token-oriented 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 and capabilities of the OpenID Providers
        (OPs) that are used by the RDAP server.  This information is
        returned in the rdapConformance section of the response.  A
        value of "farv1" indicates support for the extension described
        in this specification.  If one or more remote OpenID Providers
        are supported, the RDAP client SHOULD evaluate the additional
        information described in Section 4.1 in order to discover the
        capabilities of the RDAP server and optionally obtain the set of
        supported OPs.  Support for token-oriented clients requires a
        default OP.
   2.   The RDAP client determines the End-User's OP and confirms that
        it's supported by the RDAP server.
   3.   The RDAP client sends an Authentication Request to the OP's
        Authorization Endpoint.
   4.   The OP authenticates the End-User.
   5.   The OP obtains End-User consent/authorization.
   6.   The OP returns an Authorization Code to the RDAP client.
   7.   The RDAP client requests tokens using the Authorization Code at
        the OP's Token Endpoint.
   8.   The RDAP client receives a response that contains an ID Token
        and an Access Token in the response body.
   9.   The RDAP client monitors the token validity period and either
        refreshes the token or requests new tokens as necessary.
   10.  The RDAP client sends queries that require user identification,
        authentication, and authorization to an RDAP server that include
        an Access Token in an HTTP "Authorization" header using the
        "Bearer" authentication scheme described in RFC 6750 [RFC6750].
   11.  The RDAP server validates the Access Token and retrieves the
        claims associated with the End-User's identity from the OP's
        UserInfo Endpoint.
   12.  The RDAP server determines the End-User's authorization level
        and processes the query in accordance with server policies.

   The steps above can be described in a sequence diagram:

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   End          OpenID         RDAP                 RDAP
   User        Provider       Client               Server
     |             |             |                    |
     |             |             |-----Help Query---->|
     |             |             |                    |
     |             |             |<----Help Response--|
     |             |             |                    |
     |-------Login Request------>|                    |
     |             |             |                    |
     |             |<-Authentication                  |
     |             |   Request---|                    |
     |             |             |                    |
     |<-Credential |             |                    |
     |   Request---|             |                    |
     |             |             |                    |
     |--Credential |             |                    |
     |   Response->|             |                    |
     |             |             |                    |
     |             |--Authentication                  |
     |             | Response--->|                    |
     |             |             |                    |
     |             |<-Token      |                    |
     |             |  Request----|                    |
     |             |             |                    |
     |             |--Token      |                    |
     |             |  Response-->|                    |
     |             |             |                    |
     |<------Login Response------|                    |
     |             |             |                    |
     |-----RDAP Query----------->|                    |
     |             |             |                    |
     |             |             |----RDAP Query----->|
     |             |             |                    |
     |             |<------------Claim                |
     |             |            Request---------------|
     |             |             |                    |
     |             |-------------Claim                |
     |             |            Response------------->|
     |             |             |                    |
     |             |             |<---RDAP Response---|
     |             |             |                    |
     |<----RDAP Response---------|                    |

                                  Figure 2

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3.1.4.  RDAP Authentication and Authorization Steps

   End-Users MAY present an identifier (an OpenID) issued by an OP to
   use OpenID Connect with RDAP.  If the RDAP server supports a default
   OpenID Provider or provider discovery is not supported, the End-User
   identifier MAY be omitted.  An OP SHOULD include support for the
   claims described in Section 3.1.5 to provide additional information
   needed for RDAP End-User authorization; in the absence of these
   claims clients and servers MAY make authorization and access control
   decisions as appropriate given any other information returned from
   the OP.  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.

3.1.4.1.  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.

   Alternatively, if mapping of an End-User's identifier is not
   possible, or not supported by the RDAP server, the RDAP server SHOULD
   support explicit specification of a remote OP by the RDAP client in
   the form of a query parameter as described in Section 5.2.2 unless
   the remote OP has been identified using an out-of-band mechanism.  An
   RDAP server MUST provide information about its capabilities and
   supported OPs in the "help" query response in the
   "farv1_openidcConfiguration" data structure described in Section 4.1.
   An RDAP server/RP MUST support at least one of these methods of OP
   discovery.

3.1.4.2.  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.

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   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.  At the
   time of this writing, the Implicit Flow is considered insecure and
   efforts are being made to deprecate the flow.  The Hybrid Flow
   (described in Section 3.3 of the OpenID Connect Core protocol)
   combines elements of the Authorization Code 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 "farv1_id" query
   parameter of the End-User's RDAP "login" request, if provided.
   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.

3.1.4.3.  End-User Authorization

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

3.1.4.4.  Authorization Response and Validation

   After obtaining an authorization result, the OP will send a response
   to the RP that provides the result of the authorization process using
   an Authorization Code.  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].

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3.1.4.5.  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 3.1.3.5 of the OpenID
   Connect Core protocol [OIDCC].

3.1.4.6.  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 are 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 of
   the OpenID Connect Core protocol [OIDCC].  Additional claims for RDAP
   are described in Section 3.1.5.

3.1.5.  Specialized Claims and Authorization Scope 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.  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".

3.1.5.1.  Stated Purposes

   Communities of RDAP users and operators may wish to make and validate
   claims about a user's "need to know" when it comes to requesting
   access to a protected 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
   may need to be able to receive and validate that claim.  These needs
   can be met by defining and using an additional
   "rdap_allowed_purposes" claim.

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   The "rdap_allowed_purposes" claim identifies the purposes for which
   access to a protected resource can be requested by an End-User.  Use
   of the "rdap_allowed_purposes" claim is OPTIONAL; processing of this
   claim is subject to server acceptance of the purposes, the trust
   level assigned to this claim by the server, 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.  See Section 9.3
   for a description of the IANA considerations associated with this
   claim.

   The "rdap_allowed_purposes" claim is represented as an array of case-
   sensitive StringOrURI values as specified in Section 2 of the JSON
   Web Token (JWT) specification ([RFC7519]).  An example:

   "rdap_allowed_purposes": ["domainNameControl","dnsTransparency"]

   Purpose values are assigned to an End User's credential by an
   Identity Provider.  Identity Providers MUST ensure that appropriate
   purpose values are only assigned to End User identities that are
   authorized to use them.

3.1.5.2.  Do Not Track

   Communities of RDAP users and operators may 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 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 may 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" ("rdap_dnt_allowed") 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 "rdap_dnt_allowed" 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 "rdap_dnt_allowed"
   claim is present, the value of the claim is "true", and accepting the
   claim complies with local regulations regarding logging and tracking.

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

   rdap_dnt_allowed: true

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   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.  Common Protocol Features

   As described in Section 3.1.4.1, an RDAP server MUST provide
   information about its capabilities and supported OPs in a "help"
   query response.  This specification describes a new
   "farv1_openidcConfiguration" data structure that describes the OpenID
   Connect configuration and related extension features supported by the
   RDAP server.  This data structure is returned to all client types.

4.1.  OpenID Connect Configuration

   The "farv1_openidcConfiguration" data structure is an object with the
   following members:

   1.  "sessionClientSupported": (REQUIRED) a boolean value that
       describes RDAP server support for session-oriented clients (see
       Section 3.1.2).
   2.  "tokenClientSupported": (REQUIRED) a boolean value that describes
       RDAP server support for token-oriented clients (see
       Section 3.1.2).
   3.  "dntSupported": (REQUIRED) a boolean value that describes RDAP
       server support for the "farv1_dnt" query parameter (see
       Section 4.2.2).
   4.  "providerDiscoverySupported": (OPTIONAL) a boolean value that
       describes RDAP server support for discovery of providers of End-
       User identifiers.  The default value is "true".
   5.  "issuerIdentifierSupported": (OPTIONAL) a boolean value that
       describes RDAP server support for explicit client specification
       of an Issuer Identifier.  The default value is "true".
   6.  "implicitTokenRefreshSupported": (OPTIONAL) a boolean value that
       describes RDAP server support for implicit token refresh.  The
       default value is "false".
   7.  "openidcProviders": (OPTIONAL) a list of objects with the
       following members that describes the set of OPs that are
       supported by the RDAP server.  This data is RECOMMENDED if the
       value of issuerIdentifierSupported is "true":
       a.  "iss": (REQUIRED) a URI value that represents the Issuer
           Identifier of the OP as per the OpenID Connect Core
           specification [OIDCC]
       b.  "name": (REQUIRED) a string value representing the human-
           friendly name of the OP.

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       c.  "default": (OPTIONAL) a boolean value that describes RDAP
           server support for an OPTIONAL default OP that will be used
           when a client omits the "farv1_id" and "farv1_iss" query
           parameters from a "farv1_session/login" request.  Only one
           member of this set can be identified as the default OP by
           setting a value of "true".  The default value is "false".
       d.  "additionalAuthorizationQueryParams": (OPTIONAL) an object
           where each member represents an OAuth authorization request
           parameter name-value pair supported by the OP.  The name
           represents an OAuth query parameter and the value is the
           query parameter value.  A token-oriented RDAP client SHOULD
           add these query parameters and their corresponding values to
           the Authentication Request URL when requesting authorization
           by a specified OP through a proxy OP.

   An RDAP server MUST set either the "sessionClientSupported" or
   "tokenClientSupported" value to "true".  Both values MAY be set to
   "true" if an RDAP server supports both types of client.

   The "providerDiscoverySupported" value has a direct impact on the use
   of the "farv1_id" query parameter described in Section 3.1.4.2 and
   Section 5.2.1.  The value of "providerDiscoverySupported" MUST be
   "true" for an RDAP server to properly accept and process "farv1_id"
   query parameters.  Similarly, The "issuerIdentifierSupported" value
   has a direct impact on the use of the "farv1_iss" query parameter
   described in Section 5.2.2.  The value of "issuerIdentifierSupported"
   MUST be "true" for an RDAP server to properly accept and process
   "farv1_iss" query parameters.

   An example of a "farv1_openidcConfiguration" data structure:

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   "farv1_openidcConfiguration": {
     "sessionClientSupported": true,
     "tokenClientSupported": true,
     "dntSupported": false,
     "providerDiscoverySupported": true,
     "issuerIdentifierSupported": true,
     "openidcProviders":
       [
         {
           "iss": "https://idp.example.com",
           "name": "Example IDP"
         },
         {
           "iss": "https://accounts.example.net",
           "name": "Login with EXAMPLE",
           "additionalAuthorizationQueryParams": {
             "kc_idp_hint": "examplePublicIDP"
           }
         },
         {
           "iss": "https://auth.nic.example/auth/realms/rdap",
           "name": "Default OP for the Example RDAP server",
           "default": true
         }
       ]
   }

                                  Figure 3

4.2.  RDAP Query Parameters

   This specification describes two OPTIONAL query parameters for use
   with RDAP queries that request access to information associated with
   protected resources:

   1.  "farv1_qp": A query parameter to identify the purpose of the
       query.
   2.  "farv1_dnt": A query parameter to request that the server not log
       or otherwise record information about the identity associated
       with a query.

   One or both parameters MAY be added to an RDAP request URI using the
   syntax described in the "application/x-www-form-urlencoded" section
   of the WHATWG URL Standard [HTMLURL].

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4.2.1.  RDAP Query Purpose

   This query is represented as a "key=value" pair using a key value of
   "farv1_qp" and a value component that contains a single query purpose
   string from the set of allowed purposes associated with the End-
   User's identity (see Section 3.1.5.1).  If present, the server SHOULD
   compare the value of the parameter to the "rdap_allowed_purposes"
   claim values associated with the End-User's identity and ensure that
   the requested purpose is present in the set of allowed purposes.  The
   RDAP server MAY choose to ignore both requested purpose and the
   "rdap_allowed_purposes" claim values if they are inconsistent with
   local server policy.  The server MUST return an HTTP 403 (Forbidden)
   response if the requested purpose is not an allowed purpose.  If the
   "farv1_qp" parameter is not present, the server MUST process the
   query and make an access control decision based on any other
   information known to the server about the End-User and the
   information they are requesting.  For example, a server MAY treat the
   request as one performed by an unidentified or unauthenticated user
   and return either an error or an appropriate subset of the available
   data.  An example domain query using the "farv1_qp" query parameter:

   https://example.com/rdap/domain/example.com?farv1_qp=legalActions

4.2.2.  RDAP Do Not Track

   This query is represented as a "key=value" pair using a key value of
   "farv1_dnt" and a value component that contains a single boolean
   value.  A value of "true" indicates that the End-User is requesting
   that their query is not tracked or logged in accordance with server
   policy.  A value of "false" indicates that the End-User is accepting
   that their query can be tracked or logged in accordance with server
   policy.  The server MUST return an HTTP 403 (Forbidden) response if
   the server is unable to perform the action requested by this query
   parameter.  An example domain query using the "farv1_dnt" query
   parameter:

   https://example.com/rdap/domain/example.com?farv1_dnt=true

4.2.3.  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.  RDAP servers MUST reject
   queries that include identification information that is not
   associated with a supported OP by returning an HTTP 400 (Bad Request)
   response.  An RDAP server that receives a query containing
   identification information associated with a recognized OP MUST

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   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.  Protocol Features for Session-Oriented Clients

   This specification adds the following features to RDAP that are
   commonly used by session-oriented clients:

   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.  A query parameter to support authentication for a specific End-
       User identity on a device with a constrained user interface.
   4.  A query parameter to identify the purpose of the query.
   5.  A query parameter to request that the server not log or otherwise
       record information about the identity associated with a query.
   6.  Path segments to start, stop, refresh, and determine the status
       of an authenticated session for a specific End-User identity.

5.1.  Data Structures

   This specification describes two new data structures that are used to
   return information to a session-oriented client: a "farv1_session"
   data structure that contains information that describes an
   established session, and a "farv1_deviceInfo" data structure that
   contains information that describes an active attempt to establish a
   session on a UI-constrained device.

5.1.1.  Session

   The "farv1_session" data structure is an object that contains the
   following members:

   1.  "userID": an OPTIONAL string value that represents the End-User
       identifier associated with the session.
   2.  "iss": an OPTIONAL URI value that represents the issuer of the
       End-User identifier associated with the session.
   3.  "userClaims": an OPTIONAL object that contains the set of claims
       associated with the End-User's identity based on the user
       information provided by the OP as described in Section 3.1.4.6
       and processed by the RDAP server in the authentication and
       authorization process.  The set of possible values is determined
       by OP policy and RDAP server policy.
   4.  "sessionInfo": an OPTIONAL object that contains two members:

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       a.  "tokenExpiration": an integer value that represents the
           number of seconds that remain in the lifetime of the Access
           Token, 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.

   Note that all of the members of the "farv1_session" data structure
   are OPTIONAL.  See Section 5.2.3 for instructions describing when to
   return the minimum set of members.

   An example of a "farv1_session" data structure:

     "farv1_session": {
       "userID": "user.idp.example",
       "iss": "https://idp.example.com",
       "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",
         "rdap_allowed_purposes": [
           "domainNameControl",
           "personalDataProtection"
         ],
         "rdap_dnt_allowed": false
       },
       "sessionInfo": {
         "tokenExpiration": 3599,
         "tokenRefresh": true
       }
     }

                                  Figure 4

5.1.2.  Device Info

   The flow described in Section 3.1.4 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
   (https://curl.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

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   browser is contained in the "farv1_deviceInfo" data structure, an
   object that contains members as described in Section 3.2 ("Device
   Authorization Response") of RFC 8628 [RFC8628].

   An example of a "farv1_deviceInfo" data structure:

     "farv1_deviceInfo": {
       "device_code": "AH-1ng2ezu",
       "user_code": "NJJQ-GJFC",
       "verification_uri": "https://www.example.com/device",
       "verification_uri_complete":
          "https://www.example.com/device?user_code=NJJQ-GJFC",
       "expires_in": 1800,
       "interval": 5
     }

                                  Figure 5

5.2.  Client Login

   Client authentication is requested by sending a "farv1_session/login"
   request to an RDAP server.  If the RDAP server supports only remote
   OpenID Providers, the "farv1_session/login" request MUST include at
   least one of an End-User Identifier or an OP Issuer Identifier.

   The server sets an HTTP cookie as described in RFC 6265 [RFC6265]
   when the "farv1_session/login" request is received and processed
   successfully.  The client MUST include the session cookie received
   from the server in any RDAP request within the scope of that session,
   including "farv1_session/refresh", "farv1_session/status" and
   "farv1_session/logout".  A "farv1_session/login" followed by another
   "farv1_session/login" that does not include an HTTP cookie MUST start
   a new session on the server that includes a new cookie.  A server
   that receives a "farv1_session/login" followed by another
   "farv1_session/login" that includes an HTTP cookie MUST return an
   HTTP 409 (Conflict) response.

   To help reduce the risk of resource starvation, a server MAY reject a
   "farv1_session/login" request and refuse to start a new session by
   returning an HTTP 409 (Conflict) response if a server-side maximum
   number of concurrent sessions per user exists and the client exceeds
   that limit.  Additionally, an active session MAY be removed by the
   server due to timeout expiration or because a maximum session
   lifetime has been exceeded.  Clients SHOULD proactively monitor the
   "tokenExpiration" value associated with an active session and refresh
   the session as appropriate to provide a positive user experience.

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5.2.1.  End-User Identifier

   The End-User identifier is delivered using one of two methods: by
   adding a query component to an RDAP request URI using the syntax
   described in the "application/x-www-form-urlencoded" section of
   WHATWG URL Standard [HTMLURL], or by including an HTTP
   "Authorization" request 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 OpenID Providers and provider discovery.  Servers that support
   remote OpenID Providers and provider discovery MUST accept both
   methods.  If the RDAP server supports a default OpenID Provider or
   provider discovery is not supported, the End-User identifier MAY be
   omitted.

   The query parameter used to deliver the End-User identifier is
   represented as an OPTIONAL "key=value" pair using a key value of
   "farv1_id" and a value component that contains the client identifier
   issued by an OP.  An example for client identifier
   "user.idp.example":

   ========== NOTE: '\' line wrapping per RFC 8792 ===========

   https://example.com/rdap/farv1_session/\
   login?farv1_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/farv1_session/login

   Authorization: Basic dXNlci5pZHAuZXhhbXBsZQ==

   An example for use with a default OpenID Provider:

   https://example.com/rdap/farv1_session/login

5.2.2.  OP Issuer Identifier

   The OP's Issuer Identifier is delivered by adding a query component
   to an RDAP request URI using the syntax described in the
   "application/x-www-form-urlencoded" section of WHATWG URL Standard
   [HTMLURL].  If the RDAP server supports a default OpenID Provider,
   the Issuer Identifier MAY be omitted.

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   The query parameter used to deliver the OP's Issuer Identifier is
   represented as an OPTIONAL "key=value" pair using a key value of
   "farv1_iss" and a value component that contains the Issuer Identifier
   associated with an OP.  An RDAP server MAY accept Issuer Identifiers
   not specified in the "farv1_openidcConfiguration" data structure and
   MAY also decide to accept specific Issuer Identifiers only from
   specific clients.  An example for Issuer Identifier
   "https://idp.example.com":

   ========== NOTE: '\' line wrapping per RFC 8792 ===========

   https://example.com/rdap/farv1_session/\
   login?farv1_iss=https://idp.example.com

5.2.3.  Login Response

   The response to this request MUST be a valid RDAP response, per RFC
   9083 [RFC9083].  It MUST NOT include any members that relate to a
   specific RDAP object type (e.g., "events", "status").  In addition,
   the response MAY include an indication of the requested operation's
   success or failure in the "notices" data structure.  If successful,
   the response MUST include a "farv1_session" data structure that
   includes a "sessionInfo" object and an OPTIONAL "userClaims" object.
   If unsuccessful, the response MUST include a "farv1_session" data
   structure that omits the "userClaims" and "sessionInfo" objects.

   An example of a successful "farv1_session/login" response:

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       {
         "rdapConformance": [
           "farv1"
         ],
         "lang": "en-US",
         "notices": [
           {
             "title": "Login Result",
             "description": [
               "Login succeeded"
             ]
           }
         ],
         "farv1_session": {
           "userID": "user.idp.example",
           "iss": "https://idp.example.com",
           "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",
             "rdap_allowed_purposes": [
               "domainNameControl",
               "personalDataProtection"
             ],
             "rdap_dnt_allowed": false
           },
           "sessionInfo": {
             "tokenExpiration": 3599,
             "tokenRefresh": true
           }
         }
       }

                                  Figure 6

   An example of a failed "farv1_session/login" response:

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       {
         "rdapConformance": [
           "farv1"
         ],
         "lang": "en-US",
         "notices": [
           {
             "title": "Login Result",
             "description": [
               "Login failed"
             ]
           }
         ],
         "farv1_session": {
           "userID": "user.idp.example",
           "iss": "https://idp.example.com"
         }
       }

                                  Figure 7

5.2.4.  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
   conventional 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.

5.2.4.1.  UI-constrained Client Login

   Client authentication is requested by sending a "farv1_session/
   device" request to an RDAP server.  If the RDAP server supports only
   remote OpenID Providers, the "farv1_session/device" request MUST
   include either an End-User identifier as described in Section 5.2.1
   or an OP Issuer Identifier as described in Section 5.2.2.

   ========== NOTE: '\' line wrapping per RFC 8792 ===========

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

      wget -qO- "https://example.com/rdap/farv1_session/device\
      ?farv1_id=user.idp.example"

                                  Figure 8

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   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.

   ========== NOTE: '\' line wrapping per RFC 8792 ===========

   An example using curl and an authorization header:

      curl -H "Authorization: Basic dXNlci5pZHAuZXhhbXBsZQ=="\
      "https://example.com/rdap/farv1_session/device"

                                  Figure 9

   The response to this request MUST be a valid RDAP response, per RFC
   9083 [RFC9083].  It MUST NOT include any members that relate to a
   specific RDAP object type (e.g., "events", "status").  In addition,
   the response MAY include an indication of the requested operation's
   success or failure in the "notices" data structure, and, if
   successful, a "farv1_deviceInfo" data structure.

   An example of a "farv1_session/device" response:

     {
       "rdapConformance": [
         "farv1"
       ],
       "lang": "en-US",
       "notices": [
         {
           "title": "Device Login Result",
           "description": [
             "Login succeeded"
           ]
         }
       ],
       "farv1_deviceInfo": {
         "device_code": "AH-1ng2ezu",
         "user_code": "NJJQ-GJFC",
         "verification_uri": "https://www.example.com/device",
         "verification_uri_complete":
                 "https://www.example.com/device?user_code=NJJQ-GJFC",
         "expires_in": 1800,
             "interval": 5
       }
     }

                                 Figure 10

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5.2.4.2.  UI-constrained Client Login Polling

   After successful processing of the "farv1_session/device" request,
   the client MUST send a "farv1_session/devicepoll" request to the RDAP
   server to continue the login process.  This request initiates the
   polling function described in RFC 8628 [RFC8628] on the RDAP server.
   The RDAP server polls the OP as described in Section 3.4 of RFC 8628,
   allowing the RDAP server to wait for the End-User to enter the
   information returned from the "farv1_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.  If the RDAP server supports only remote OpenID Providers,
   the "farv1_session/devicepoll" request MUST include either an End-
   User identifier as described in Section 5.2.1 or an OP Issuer
   Identifier as described in Section 5.2.2.

   The "farv1_session/devicepoll" request MUST also include a "farv1_dc"
   query parameter.  The query parameter is represented as an OPTIONAL
   "key=value" pair using a key value of "farv1_dc" and a value
   component that contains the value of the device_code that was
   returned in the response to the "farv1_session/device" request.

   ========== NOTE: '\' line wrapping per RFC 8792 ===========

   An example using wget:

      wget -qO- --keep-session-cookies --save-cookies cookie.txt\
      "https://example.com/rdap/farv1_session/devicepoll\
      ?farv1_id=user.idp.example&farv1_dc=AH-1ng2ezu"

                                 Figure 11

   An example using curl:

      curl -c cookie.txt "https://example.com/rdap/farv1_session/\
      devicepoll?farv1_id=user.idp.example&farv1_dc=AH-1ng2ezu"

                                 Figure 12

   The response to this request MUST use the response structures
   described in Section 5.2.  RDAP query processing can continue
   normally on the UI-constrained device once the device polling process
   has been completed successfully.

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5.3.  Session Status

   Clients MAY send a query to an RDAP server to determine the status of
   an existing login session using a "farv1_session/status" path
   segment.  An example "farv1_session/status" request:

   https://example.com/rdap/farv1_session/status

   The response to this request MUST be a valid RDAP response, per RFC
   9083 [RFC9083].  It MUST NOT include any members that relate to a
   specific RDAP object type (e.g., "events", "status").  In addition,
   the response MAY include an indication of the requested operation's
   success or failure in the "notices" data structure.  If the operation
   is successful, and an active session exists, the response MUST
   include a "farv1_session" data structure that includes a
   "sessionInfo" object and an OPTIONAL "userClaims" object.  If the
   operation is unsuccessful, or if no active session exists, the
   response MUST NOT include a "farv1_session" object.

   An example of a "farv1_session/status" response for an active
   session:

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     {
       "rdapConformance": [
         "farv1"
       ],
       "lang": "en-US",
       "notices": [
         {
           "title": "Session Status Result",
           "description": [
             "Session status succeeded"
           ]
         }
       ],
       "farv1_session": {
         "userID": "user.idp.example",
         "iss": "https://idp.example.com",
         "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",
           "rdap_allowed_purposes": [
             "domainNameControl",
             "personalDataProtection"
           ],
           "rdap_dnt_allowed": false
         },
         "sessionInfo": {
           "tokenExpiration": 3490,
           "tokenRefresh": true
         }
       }
     }

                                 Figure 13

   If the operation is successful, and an active session does not exist,
   the response MAY note the lack of an active session in the "notices"
   data structure.  The "farv1_session" data structure MUST be omitted.

   An example of a "farv1_session/status" response with no active
   session:

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     {
       "rdapConformance": [
         "farv1"
       ],
       "lang": "en-US",
       "notices": [
         {
           "title": "Session Status Result",
           "description": [
             "Session status succeeded",
             "No active session"
           ]
         }
       ]
     }

                                 Figure 14

5.4.  Session Refresh

   Clients MAY send a request to an RDAP server to refresh, or extend,
   an existing login session using a "farv1_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 "farv1_session/refresh" request:

   https://example.com/rdap/farv1_session/refresh

   The response to this request MUST be a valid RDAP response, per RFC
   9083 [RFC9083].  It MUST NOT include any members that relate to a
   specific RDAP object type (e.g., "events", "status").  In addition,
   the response MAY include an indication of the requested operation's
   success or failure in the "notices" data structure.  The response
   MUST include a "farv1_session" data structure that includes a
   "sessionInfo" object and an OPTIONAL "userClaims" object.  If
   unsuccessful, but an active session exists, the response MUST include
   a "farv1_session" data structure that includes a "sessionInfo" object
   and an OPTIONAL "userClaims" object.  If unsuccessful, and no active
   session exists, the response MUST omit the "farv1_session" data
   structure.

   An example of a successful "farv1_session/refresh" response:

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     {
       "rdapConformance": [
         "farv1"
       ],
       "lang": "en-US",
       "notices": [
         {
           "title": "Session Refresh Result",
           "description": [
             "Session refresh succeeded",
             "Token refresh succeeded."
           ]
         }
       ],
       "farv1_session": {
         "userID": "user.idp.example",
         "iss": "https://idp.example.com",
         "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",
           "rdap_allowed_purposes": [
             "domainNameControl",
             "personalDataProtection"
           ],
           "rdap_dnt_allowed": false
         },
         "sessionInfo": {
           "tokenExpiration": 3599,
           "tokenRefresh": true
         }
       }
     }

                                 Figure 15

   Alternatively, an RDAP server MAY attempt to refresh an Access Token
   upon receipt of a query if the Access Token associated with an
   existing session has expired and the corresponding OP supports token
   refresh.  The default RDAP server behavior is described in the
   "implicitTokenRefreshSupported" value that's included in the
   "farv1_openidcConfiguration" data structure (see Section 4.1).

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   If the value of "implicitTokenRefreshSupported" is "true", the client
   MAY either explicitly attempt to refresh the session using the
   "farv1_session/refresh" query, or it MAY depend on the RDAP server to
   attempt to refresh the session as necessary when an RDAP query is
   received by the server.  In this case, a server MUST attempt to
   refresh the Access Token upon receipt of a query if the Access Token
   associated with an existing session has expired and the corresponding
   OP supports token refresh.  Servers MUST return an HTTP 401
   (Unauthorized) response to a query if an attempt to implicitly
   refresh an existing session fails.

   If the value of "implicitTokenRefreshSupported" is "false", the
   client MUST explicitly attempt to refresh the session using the
   "farv1_session/refresh" query to extend an existing session.  If a
   session cannot be extended for any reason, the client MUST establish
   a new session to continue authenticated query processing by
   submitting a "farv1_session/login" query.  If the OP does not support
   token refresh, the client MUST submit a new "farv1_session/login"
   request to establish a new session once an Access Token has expired.

   Clients SHOULD NOT send a "farv1_session/refresh" request in the
   absence of an active login session because the request conflicts with
   the current state of the server.  Servers MUST return an HTTP 409
   (Conflict) response if a "farv1_session/refresh" request is received
   in the absence of a session cookie.

5.5.  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
   "farv1_session/logout" path segment.  Access and refresh tokens can
   be revoked during the "farv1_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 log out from the OP using the "OpenID Connect RP-
   Initiated Logout" protocol ([OIDCL]) if that protocol is supported by
   the OP.  In any case, to prevent abuse before the cookie times out an
   RDAP server SHOULD invalidate the HTTP cookie associated with the
   session as part of terminating the session.

   An example "farv1_session/logout" request:

   https://example.com/rdap/farv1_session/logout

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   The response to this request MUST be a valid RDAP response, per RFC
   9083 [RFC9083].  It MUST NOT include any members that relate to a
   specific RDAP object type (e.g., "events", "status").  In addition,
   the response MAY include an indication of the requested operation's
   success or failure in the "notices" data structure.  The "notices"
   data structure MAY 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 "farv1_session/logout" response:

     {
       "rdapConformance": [
         "farv1"
       ],
       "lang": "en-US",
       "notices": [
         {
           "title": "Logout Result",
           "description": [
             "Logout succeeded"
             "Provider logout failed: Not supported by provider.",
             "Token revocation successful."
           ]
         }
       ]
     }

                                 Figure 16

   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.

5.6.  Request Sequencing

   The requests described in this document are typically performed in a
   specific sequence: "farv1_session/login" (or the related
   "farv1_session/device" and "farv1_session/devicepoll" requests) to
   start a session, "farv1_session/status" and/or "farv1_session/
   refresh" to manage a session, and "farv1_session/logout" to end a
   session.  If a client sends a "farv1_session/status", "farv1_session/
   refresh", or "farv1_session/logout" request in the absence of a
   session cookie, the server MUST return an HTTP 409 (Conflict) error.

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   A client can end a session explicitly by sending a "farv1_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
   "farv1_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 every query.

   An RDAP server can receive queries that include a session cookie
   where the associated session has expired or is otherwise unavailable
   (e.g., due to the user requesting explicit logout for the associated
   session).  The server MUST return an HTTP 401 (Unauthorized) error in
   response to such queries.

6.  Protocol Features for Token-Oriented Clients

   This specification adds additional processing steps for token-
   oriented clients as described in this section and Section 3.1.3.  It
   does not define additional data structures or RDAP-specific protocol
   parameters specifically for token-oriented clients.

6.1.  Client Login

   Clients identify and authenticate End-Users by exchanging information
   with an OP that is recognized by the RDAP server as described in
   Section 3.1.4.2, Section 3.1.4.3, and Section 3.1.4.4.  A client
   SHOULD append the "additionalAuthorizationQueryParams" values
   retrieved from the "openidcProviders" array described in Section 4.1
   to the Authorization Endpoint URL when requesting authorization from
   the OP.  Once these processes are completed successfully, the client
   can request tokens from the OP as described in Section 3.1.4.5.  The
   OP SHOULD include the RDAP server's client_id in the "aud" claim
   value of an issued ID token.  The RDAP server MAY choose to ignore
   the value of the "aud" claim or exchange the token as described in
   Section 6.4.  With these steps completed, the Access Token received
   from the OP can be passed to an RDAP server in an HTTP
   "Authorization" request header [RFC6750] for RDAP queries that
   require End-User identification, authentication, and authorization.

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6.2.  Client Queries

   An RDAP server that receives a bearer token in an HTTP
   "Authorization" request header as part of an RDAP object query MUST
   validate the token in accordance with local policy and confirm that
   the token is a legitimate Access Token.  Once validated, the Access
   Token MAY be used to retrieve the claims associated with the End-
   User's identity, including claims associated with the "rdap" scope
   that are not already included in the Access Token, as described in
   Section 3.1.4.6.  The RDAP server can then evaluate the End-User's
   identity information to determine the End-User's authorization level
   and process the query in accordance with server policies.  A client
   MUST include the "farv1_iss" query parameter and issuer identifier
   value with an RDAP query if the token was issued by a remote OP.

6.3.  Access Token Validation

   An RDAP server MUST validate a received Access Token prior to using
   that token for access control purposes.  Validation MAY include token
   introspection [RFC7662] using the issuing OP, or analysis of the
   values included in a JWT Access Token.  Once an Access Token is
   validated, an RDAP server MAY use that token to request user claims
   from the issuing OP.

   There are performance considerations associated with the process of
   validating a token and requesting user claims as part of processing
   every received RDAP query.  An RDAP server MAY cache validated
   information and use that cached information to reduce the amount of
   time needed to process subsequent RDAP queries associated with the
   same Access Token as long as the token has not expired.  The client
   SHOULD monitor the token expiration time and refresh the token as
   needed.

6.4.  Token Exchange

   Tokens can include an "aud" (audience) claim 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 "aud" claim 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 the Access Token with the OP for a
   set of trusted tokens that reset the "aud" claim.  The token exchange
   protocol is described in RFC 8693 [RFC8693].

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7.  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.

8.  RDAP Conformance

   RDAP responses that contain values described in this document MUST
   indicate conformance with this specification by including an
   rdapConformance ([RFC9083]) value of "farv1" (Federated
   Authentication for RDAP version 1).  The information needed to
   register this value in the RDAP Extensions Registry is described in
   Section 9.1.

   Example rdapConformance structure with extension specified:

      "rdapConformance" :
        [
          "rdap_level_0",
          "farv1"
        ]

                                 Figure 17

9.  IANA Considerations

9.1.  RDAP Extensions Registry

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

      Extension identifier: farv1
      Registry operator: Any
      Published specification: This document.
      Contact: IETF <iesg@ietf.org>
      Intended usage: This extension describes version 1 of a federated
      authentication method for RDAP using OAuth 2.0 and OpenID Connect.

9.2.  JSON Web Token Claims Registry

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

      Claim Name: "rdap_allowed_purposes"

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      Claim Description: This claim describes the set of RDAP query
      purposes that are available to an identity that is presented for
      access to a protected RDAP resource.
      Change Controller: IETF
      Specification Document(s): Section 3.1.5.1 of this document.

      Claim Name: "rdap_dnt_allowed"
      Claim Description: This claim contains a JSON boolean literal that
      describes a "do not track" request for server-side tracking,
      logging, or recording of an identity that is presented for access
      to a protected RDAP resource.
      Change Controller: IETF
      Specification Document(s): Section 3.1.5.2 of this document.

9.3.  RDAP Query Purpose Registry

   IANA is requested to create a new protocol registry to manage RDAP
   query purpose values.

   Section at https://www.iana.org/protocols: Registration Data Access
   Protocol (RDAP)

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

   Registration policy: This registry is operated under the
   "Specification Required" policy defined in RFC 8126 ([RFC8126]).  The
   Designated Expert must ensure that requests to add values to this
   registry meet the syntax, value, and description requirements
   described in this section.

   Required information: Registration requests are described in a
   specification that's consistent with the "Specification Required"
   policy defined in RFC 8126 ([RFC8126]).  The specification must
   include one or more purpose values as described below.

   Size, format, and syntax of registry entries:

   Individual purpose values are 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 ASCII 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.

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

   Initial assignments and reservations:

   The set of initial values used to populate the registry as described
   here 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).

   -----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 website
      functional issues.

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

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   -----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: academicPublicInterestDNSResearch

      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

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      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 public.

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

10.  Implementation Status

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

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   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.

10.1.  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 be minimally maintained.  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 the features described
      in this specification.
      Version compatibility: Version -11+ of this specification.
      Contact Information: Scott Hollenbeck, shollenbeck@verisign.com

10.2.  Verisign Labs

      Responsible Organization: Verisign Labs
      Location: https://rdap.verisignlabs.com/

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      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 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 the information available
          to a Basic client plus whatever information the server
          operator deems appropriate for a fully authorized client.
          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 the features described
      in this specification.
      Version compatibility: Version -07 of this specification.
      Contact Information: Scott Hollenbeck, shollenbeck@verisign.com

10.3.  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 levels of purpose 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

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11.  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; best
   current security practice for OAuth 2.0 can be found in RFC TBD
   [I-D.ietf-oauth-security-topics].  Additionally, the practices
   described in RFC 9325 [RFC9325] MUST be followed when the Transport
   Layer Security (TLS) protocol is used.

   As described in Section 3.1.4.2, the OAuth 2.0 Implicit Flow
   [RFC6749] is considered insecure and efforts are being made to
   deprecate the flow.  It MUST NOT be used.

   Some of the responses described in this specification return
   information to a client from an RDAP server that is intended to help
   the client match responses to queries and manage sessions.  Some of
   that information, such as the "userClaims" described in
   Section 5.1.1, can be personally identifiable and considered
   sensitive if disclosed to unauthorized parties.  An RDAP server
   operator must develop policies for information disclosure to ensure
   that personally identifiable information is disclosed only to clients
   that are authorized to process that information.

   The "do not track" claim relies on the good will of the RDAP server
   and associated proxies.  As such, use and processing of this claim
   depends on out-of-band trust relationships that need to be
   established before the claim is used in practice.  If used and
   accepted by the RDAP server, there is a risk of information loss that
   could seriously impair audit capabilities.

11.1.  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 (such as the set
   of "userClaims" described in Section 5.1.1) 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.

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12.  Acknowledgments

   The author would like to acknowledge the following individuals for
   their contributions to the development of this document: Julien
   Bernard, 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.

   Pawel Kowalik and Mario Loffredo provided significant text
   contributions that led to welcome improvements in several sections of
   this document.  Their contributions are greatly appreciated.

13.  References

13.1.  Normative References

   [HTMLURL]  Web Hypertext Application Technology Working Group
              (WHATWG), "URL (Living Standard)", September 2023,
              <https://url.spec.whatwg.org/#application/x-www-form-
              urlencoded>.

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

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

   [OIDCL]    OpenID Foundation, "OpenID Connect RP-Initiated Logout
              1.0", September 2022, <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, <https://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>.

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   [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>.

   [RFC6750]  Jones, M. and D. Hardt, "The OAuth 2.0 Authorization
              Framework: Bearer Token Usage", RFC 6750,
              DOI 10.17487/RFC6750, October 2012,
              <https://www.rfc-editor.org/info/rfc6750>.

   [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>.

   [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>.

   [RFC7662]  Richer, J., Ed., "OAuth 2.0 Token Introspection",
              RFC 7662, DOI 10.17487/RFC7662, October 2015,
              <https://www.rfc-editor.org/info/rfc7662>.

   [RFC8126]  Cotton, M., Leiba, B., and T. Narten, "Guidelines for
              Writing an IANA Considerations Section in RFCs", BCP 26,
              RFC 8126, DOI 10.17487/RFC8126, June 2017,
              <https://www.rfc-editor.org/info/rfc8126>.

   [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>.

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   [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>.

   [RFC9068]  Bertocci, V., "JSON Web Token (JWT) Profile for OAuth 2.0
              Access Tokens", RFC 9068, DOI 10.17487/RFC9068, October
              2021, <https://www.rfc-editor.org/info/rfc9068>.

   [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>.

   [RFC9110]  Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
              Ed., "HTTP Semantics", STD 97, RFC 9110,
              DOI 10.17487/RFC9110, June 2022,
              <https://www.rfc-editor.org/info/rfc9110>.

   [RFC9325]  Sheffer, Y., Saint-Andre, P., and T. Fossati,
              "Recommendations for Secure Use of Transport Layer
              Security (TLS) and Datagram Transport Layer Security
              (DTLS)", BCP 195, RFC 9325, DOI 10.17487/RFC9325, November
              2022, <https://www.rfc-editor.org/info/rfc9325>.

13.2.  Informative References

   [I-D.ietf-oauth-security-topics]
              Lodderstedt, T., Bradley, J., Labunets, A., and D. Fett,
              "OAuth 2.0 Security Best Current Practice", Work in
              Progress, Internet-Draft, draft-ietf-oauth-security-
              topics-24, 23 October 2023,
              <https://datatracker.ietf.org/doc/html/draft-ietf-oauth-
              security-topics-24>.

   [OIDC]     OpenID Foundation, "What is OpenID Connect",
              <https://openid.net/developers/how-connect-works/>.

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   [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>.

   [RFC8792]  Watsen, K., Auerswald, E., Farrel, A., and Q. Wu,
              "Handling Long Lines in Content of Internet-Drafts and
              RFCs", RFC 8792, DOI 10.17487/RFC8792, June 2020,
              <https://www.rfc-editor.org/info/rfc8792>.

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 3.1.4.2.  Added some
      text to Section 3.1.5.2 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 default and remote OpenID Provider processing.  Removed text
      that described passing of ID Tokens as query parameters.
   10:  Updated Section 3.1.4.1.  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 9.  Minor
      formatting changes due to a move to xml2rfc-v3 markup.

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   13:  Added support for OP discovery via OP's Issuer Identifier.
      Modified the RDAP conformance text to use "roidc1", and added that
      value to extension path segments, data structures, and query
      parameters.  Changed the "purpose" and "dnt" claims to
      "rdap_allowed_purposes" (making it an array) and
      "rdap_dnt_allowed".  Added the "roidc1_qp" and "roidc1_dnt" query
      parameters.  Changed the descriptions of "local" OPs to "default"
      OPs.
   14:  Fixed a few instances of "id" that were changed to "roidc1_id"
      and "session" that were changed to "roidc1_session".  Added
      "implicitTokenRefreshSupported".
   15:  Fixed an instance of openidcConfiguration that was missing the
      "roidc1" prefix.  Changed SHOULD to MUST to describe the need to
      return the roidc1_openidcConfiguration data structure in a "help"
      response.
   16:  Changed the "roidc1" prefix to "farv1".  Added additional
      terminology text.  Added RFC 8996 as a normative reference.
      Multiple clarifications in Sections 3, 4, and 5.  Added
      login/refresh/logout sequence and conflict response text.  Added
      "clientID" and "iss" to the "farv1_session" data structure.  Made
      the "userClaims" and "sessionInfo" objects OPTIONAL in the
      "farv1_session" data structure.  Fixed the curl example in
      Section 5.2.4.1.  Modified the "/device" and "/devicepoll"
      requests to include query parameters.  Added "device_code" to the
      "farv1_deviceInfo" data structure.  Added the "farv1_dc" query
      parameter.
   17:  Changed string "true" to boolean true in Figure 3.  Fixed the
      reference to RFC 8996.  Updated references for RFCs 5226 (to 8126)
      and 7230 (to 9110).
   18  Addressed WG last call feedback for which we had agreed-upon
      updates.
   19  Updated Security Considerations.  Updated response processing
      text.  Added and changed text to describe support for session-
      oriented and token-oriented clients.  Added reference to RFC 9068.
   20  Updated text to describe support for session-oriented and token-
      oriented clients.
   21  Changed "Servers MUST support both types of client" to "SHOULD".
      Added "sessionClientSupported" and "tokenClientSupported" as a
      consequence.  Noted that the OIDCC Implicit Flow is being
      deprecated due to security concerns.  Added additional text to
      describe the relationship between "providerDiscoverySupported" and
      "farv1_id", and "issuerIdentifierSupported" and "farv1_iss".
      Restructured Section 5.6 and Section 7.  Replaced the reference to
      RFC 2616 (obsolete) with RFC 9110.  Replaced the reference to RFC
      7231 (obsolete) with RFC 9110.
   22  Changed MANDATORY to REQUIRED for BCP 14 alignment.  Updated
      Section 3.1.2, Section 11, and Section 12.
   23  Changed "IESG" to "IETF" in Section 9 at IANA's request.

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   24  AD evaluation edits.
   25  IETF last call edits.
   26  IESG evaluation edits.
   27  IESG evaluation edit.  Changed "An RDAP server operator SHOULD
      develop policies" to "An RDAP server operator must develop
      policies" in Section 11.

Author's Address

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

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