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Federated Authentication for the Registration Data Access Protocol (RDAP) using OpenID Connect
draft-ietf-regext-rdap-openid-16

The information below is for an old version of the document.
Document Type
This is an older version of an Internet-Draft that was ultimately published as RFC 9560.
Author Scott Hollenbeck
Last updated 2022-07-29
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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draft-ietf-regext-rdap-openid-16
REGEXT Working Group                                       S. Hollenbeck
Internet-Draft                                             Verisign Labs
Intended status: Standards Track                            29 July 2022
Expires: 30 January 2023

   Federated Authentication for the Registration Data Access Protocol
                      (RDAP) using OpenID Connect
                    draft-ietf-regext-rdap-openid-16

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 30 January 2023.

Copyright Notice

   Copyright (c) 2022 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 . . . . . . . . . . . . . . . . . . . .   3
     1.2.  Proposal  . . . . . . . . . . . . . . . . . . . . . . . .   4
   2.  Conventions Used in This Document . . . . . . . . . . . . . .   4
   3.  Federated Authentication for RDAP . . . . . . . . . . . . . .   4
     3.1.  RDAP and OpenID Connect . . . . . . . . . . . . . . . . .   5
       3.1.1.  Terminology . . . . . . . . . . . . . . . . . . . . .   5
       3.1.2.  Overview  . . . . . . . . . . . . . . . . . . . . . .   6
       3.1.3.  RDAP Authentication and Authorization Steps . . . . .   7
         3.1.3.1.  Provider Discovery  . . . . . . . . . . . . . . .   7
         3.1.3.2.  Authentication Request  . . . . . . . . . . . . .   8
         3.1.3.3.  End-User Authorization  . . . . . . . . . . . . .   8
         3.1.3.4.  Authorization Response and Validation . . . . . .   9
         3.1.3.5.  Token Processing  . . . . . . . . . . . . . . . .   9
         3.1.3.6.  Delivery of User Information  . . . . . . . . . .   9
       3.1.4.  Specialized Claims for RDAP . . . . . . . . . . . . .   9
         3.1.4.1.  Stated Purposes . . . . . . . . . . . . . . . . .   9
         3.1.4.2.  Do Not Track  . . . . . . . . . . . . . . . . . .  10
   4.  Protocol Parameters . . . . . . . . . . . . . . . . . . . . .  11
     4.1.  Data Structures . . . . . . . . . . . . . . . . . . . . .  11
       4.1.1.  Session . . . . . . . . . . . . . . . . . . . . . . .  12
       4.1.2.  Device Info . . . . . . . . . . . . . . . . . . . . .  13
       4.1.3.  OpenID Connect Configuration  . . . . . . . . . . . .  14
     4.2.  Client Login  . . . . . . . . . . . . . . . . . . . . . .  15
       4.2.1.  End-User Identifier . . . . . . . . . . . . . . . . .  16
       4.2.2.  OP Issuer Identifier  . . . . . . . . . . . . . . . .  16
       4.2.3.  Login Response  . . . . . . . . . . . . . . . . . . .  17
       4.2.4.  Clients with Limited User Interfaces  . . . . . . . .  19
         4.2.4.1.  UI-constrained Client Login . . . . . . . . . . .  19
         4.2.4.2.  UI-constrained Client Login Polling . . . . . . .  20
     4.3.  RDAP Query Parameters . . . . . . . . . . . . . . . . . .  21
       4.3.1.  RDAP Query Purpose  . . . . . . . . . . . . . . . . .  22
       4.3.2.  RDAP Do Not Track . . . . . . . . . . . . . . . . . .  22
     4.4.  Session Status  . . . . . . . . . . . . . . . . . . . . .  22
     4.5.  Session Refresh . . . . . . . . . . . . . . . . . . . . .  24
     4.6.  Client Logout . . . . . . . . . . . . . . . . . . . . . .  26
     4.7.  Parameter Processing  . . . . . . . . . . . . . . . . . .  27

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     4.8.  Request Sequencing  . . . . . . . . . . . . . . . . . . .  28
   5.  Token Exchange  . . . . . . . . . . . . . . . . . . . . . . .  28
   6.  RDAP Query Processing . . . . . . . . . . . . . . . . . . . .  28
   7.  RDAP Conformance  . . . . . . . . . . . . . . . . . . . . . .  29
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  29
     8.1.  RDAP Extensions Registry  . . . . . . . . . . . . . . . .  29
     8.2.  JSON Web Token Claims Registry  . . . . . . . . . . . . .  29
     8.3.  RDAP Query Purpose Registry . . . . . . . . . . . . . . .  30
   9.  Implementation Status . . . . . . . . . . . . . . . . . . . .  33
     9.1.  Editor Implementation . . . . . . . . . . . . . . . . . .  34
     9.2.  Verisign Labs . . . . . . . . . . . . . . . . . . . . . .  34
     9.3.  Viagenie  . . . . . . . . . . . . . . . . . . . . . . . .  35
   10. Security Considerations . . . . . . . . . . . . . . . . . . .  35
     10.1.  Authentication and Access Control  . . . . . . . . . . .  35
   11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  35
   12. References  . . . . . . . . . . . . . . . . . . . . . . . . .  36
     12.1.  Normative References . . . . . . . . . . . . . . . . . .  36
     12.2.  Informative References . . . . . . . . . . . . . . . . .  38
   Appendix A.  Change Log . . . . . . . . . . . . . . . . . . . . .  38
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  39

1.  Introduction

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

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

1.1.  Problem Statement

   The traditional "user name and password" authentication method does
   not scale well in the RDAP ecosystem.  Assuming that all domain name
   and address registries will eventually provide RDAP service, it is
   impractical and inefficient for users to secure login credentials
   from the hundreds of different server operators.  Authentication
   methods based on user names and passwords do not provide information
   that describes the user in sufficient detail (while protecting the

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   personal privacy of the user) for server operators to make fine-
   grained access control decisions based on the user's identity.  The
   authentication system used for RDAP needs to address all of these
   needs.

1.2.  Proposal

   A basic level of RDAP service can be provided to users who possess an
   identifier issued by a recognized provider who 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 them self to
   gain access to that service) can secure identifiers from specialized
   providers who are or will be able to provide more detailed
   information about the user.  Server operators can then make access
   control decisions based on the identification information provided by
   the user.

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

2.  Conventions Used in This Document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

3.  Federated Authentication for RDAP

   RDAP itself does not include native security services.  Instead, RDAP
   relies on features that are available in other protocol layers to
   provide needed security services including access control,
   authentication, authorization, availability, data confidentiality,
   data integrity, and identification.  A description of each of these
   security services can be found in "Internet Security Glossary,
   Version 2" [RFC4949].  This document focuses on a federated

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   authentication system for RDAP that provides services for
   authentication, authorization, and identification, allowing a server
   operator to make access control decisions.  Section 3 of RFC 7481
   [RFC7481] describes general considerations for RDAP access control,
   authentication, and authorization.

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

3.1.  RDAP and OpenID Connect

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

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

3.1.1.  Terminology

   This document uses the terms "client" and "server" defined by RDAP
   [RFC7480].  An RDAP client performs the role of an OpenID Connect
   Core 1.0 [OIDCC] Entity or End-User.  An RDAP server performs the
   role of an OpenID Connect Core Relying Party (RP).  Additional terms
   from Section 1.2 of the OpenID Connect Core specification are
   incorporated by reference.

   This document uses the terms "Access Token", "Authorization Code",
   "Authorization Endpoint", "Authorization Grant", "Authorization
   Server", "Client Authentication", "Client Identifier", "Protected
   Resource", "Refresh Token", "Resource Owner", and "Token Endpoint"
   defined by OAuth 2.0 [RFC6749]; the terms "Claim Name", "Claim

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   Value", and "JSON Web Token (JWT)" defined by JSON Web Token (JWT)
   [RFC7519]; and the term "ID Token" defined by OpenID Connect Core 1.0
   [OIDCC].

3.1.2.  Overview

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

   1.   An RDAP client sends an RDAP "help" query to an RDAP server to
        determine the type and capabilities of the OpenID Authorization
        Servers 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 Authorization
        Servers are supported, the RDAP client SHOULD evaluate the
        additional information described in Section 4.1.3 in order to
        discover the capabilities of the RDAP server and optionally
        obtain the set of supported OPs.
   2.   An RDAP client (acting as an OpenID End-User) sends an RDAP
        "login" request to an RDAP server as described in Section 4.2.
   3.   The RDAP server (acting as an OpenID Relying Party (RP))
        prepares an Authentication Request containing the desired
        request parameters.
   4.   The RDAP server sends the RDAP client and Authentication Request
        to an Authorization Server operated by an OpenID Provider (OP)
        using an HTTP redirect.
   5.   The Authorization Server authenticates the End-User.
   6.   The Authorization Server obtains End-User consent/authorization.
   7.   The Authorization Server sends the RDAP Client back to the RDAP
        server with an Authorization Code using an HTTP redirect.
   8.   The RDAP server requests a response using the Authorization Code
        at the Token Endpoint.
   9.   The RDAP server receives a response that contains an ID Token
        and Access Token in the response body.
   10.  The RDAP server validates the ID Token and retrieves the claims
        associated with the End-User's identity.

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

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3.1.3.  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
   Authorization Server or End-User identifier discovery is not
   supported, the End-User identifier MAY be omitted.  An OP SHOULD
   include support for the claims described in Section 3.1.4 to provide
   additional information needed for RDAP End-User authorization.
   OpenID Connect requires RPs to register with OPs to use OpenID
   Connect services for an End-User.  The registration process is often
   completed using out-of-band methods, but it is also possible to use
   the automated method described by the "OpenID Connect Dynamic Client
   Registration" protocol [OIDCR].  The parties involved can use any
   method that is mutually acceptable.

3.1.3.1.  Provider Discovery

   An RDAP server/RP needs to be able to map an End-User's identifier to
   an OP.  This can be accomplished using the OPTIONAL "OpenID Connect
   Discovery" protocol [OIDCD], but that protocol is not widely
   implemented.  Out-of-band methods are also possible and can be more
   dependable.  For example, an RP can support a limited number of OPs
   and maintain internal associations of those identifiers with the OPs
   that issued them.

   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 4.2.2.  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 4.1.3.

   An RP can also ask an End-User to identify the OP that issued their
   identifier as part of an RDAP query workflow.  In this case, the RP
   will need to maintain state for the association between the user's
   identifier and the OP in order to process later queries that rely on
   passing the access token and user identifier as authorization
   parameters.  An RDAP server/RP MUST support at least one of these
   methods of OP discovery.

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3.1.3.2.  Authentication Request

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

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

   An Authentication Request can contain several parameters.  REQUIRED
   parameters are specified in Section 3.1.2.1 of the OpenID Connect
   Core protocol [OIDCC].  Apart from these parameters, it is
   RECOMMENDED that the RP include the optional "login_hint" parameter
   in the request, with the value being that of the "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.

3.1.3.3.  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].

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3.1.3.4.  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].

3.1.3.5.  Token Processing

   The RP sends a Token Request using the Authorization Grant to a Token
   Endpoint to obtain a Token Response containing an Access Token, ID
   Token, and an OPTIONAL Refresh Token.  The RP MUST validate the Token
   Response.  This process is described in Section 3.1.3.5 of the OpenID
   Connect Core protocol [OIDCC].

3.1.3.6.  Delivery of User Information

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

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

3.1.4.  Specialized Claims for RDAP

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

3.1.4.1.  Stated 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.

   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"]

   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 characters from "A" to "Z", lower case ASCII
   characters from "a" to "z", and the underscore ("_") character.
   Value strings contain at least one character and no more than 64
   characters.

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

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

3.1.4.2.  Do Not Track

   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.

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   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

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

4.  Protocol Parameters

   This specification adds the following protocol parameters to RDAP:

   1.  Data structures to return information that describes an
       established session, the information needed to establish a
       session for a UI-constrained device, and the RDAP server's OpenID
       Connect extension configuration.
   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.

4.1.  Data Structures

   This specification describes three new data structures that are used
   to return information to a client: a "farv1_session" data structure
   that contains information that describes an established session, a
   "farv1_deviceInfo" data structure that contains information that
   describes an active attempt to establish a session on a UI-
   constrained device, and a "farv1_openidcConfiguration" data structure

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   that describes the OpenID Connect configuration and related extension
   features supported by the RDAP server.

4.1.1.  Session

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

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

   An example of a "farv1_session" data structure:

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     "farv1_session": {
       "clientID": "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 1

4.1.2.  Device Info

   The flow described in Section 3.1.3 requires an End-User to interact
   with a server using a user interface that can process HTTP.  This
   will not work well in situations where the client is automated or an
   End-User is using a command line user interface such as curl
   (http://curl.haxx.se/) or wget (https://www.gnu.org/software/wget/).
   This limitation can be addressed using a web browser on a second
   device.  The information that needs to be entered using the web
   browser is contained in the "farv1_deviceInfo" data structure.

   The "farv1_deviceInfo" data structure is an object that contains
   three members:

   1.  "verification_url": a URL that the End-User needs to visit using
       a web browser on a second device,
   2.  "user_code": a string value that the End-User needs to enter on
       the form presented in the web browser,
   3.  "device_code": a string value that the client needs to deliver as
       part of a device polling request, and

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   4.  "expires_in": an integer value that represents the number of
       seconds after which the opportunity to visit the URL and enter
       the user_code will expire.

   An example of a "farv1_deviceInfo" data structure:

     "farv1_deviceInfo": {
       "verification_url": "https://www.example.com/device",
       "user_code": "NJJQ-GJFC",
       "device_code": "AH-1ng2ezu",
       "expires_in": "1800"
     }

                                  Figure 2

4.1.3.  OpenID Connect Configuration

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

   1.  "dntSupported": (MANDATORY) a boolean value that describes RDAP
       server support for the "farv1_dnt" query parameter (see
       Section 4.3.2).
   2.  "endUserIdentifierDiscoverySupported": (OPTIONAL) a boolean value
       that describes RDAP server support for discovery of End-User
       identifiers.  The default value is "true".
   3.  "issuerIdentifierSupported": (OPTIONAL) a boolean value that
       describes RDAP server support for explicit client specification
       of an Issuer Identifier.  The default value is "true".
   4.  "implicitTokenRefreshSupported": (OPTIONAL) a boolean value that
       describes RDAP server support for implicit token refresh.  The
       default value is "false".
   5.  "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": (MANDATORY) a string value equal to Issuer Identifier
           of the OP as per OpenID Connect Core specification [OIDCC]
       b.  "name": (MANDATORY) a string value representing the human-
           friendly name of the OP.
       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".

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   An example of a "farv1_openidcConfiguration" data structure:

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

                                  Figure 3

4.2.  Client Login

   Client authentication is requested by sending a "farv1_session/login"
   request to an RDAP server.  If the RDAP server supports only remote
   Authorization Servers, 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

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   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.

4.2.1.  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 Section 3.4 of RFC 3986 [RFC3986], or by including an
   HTTP authorization header for the Basic authentication scheme as
   described in RFC 7617 [RFC7617].  Clients can use either of these
   methods to deliver the End-User identifier to a server that supports
   remote Authorization Servers and End-User identifier discovery.
   Servers that support remote Authorization Servers and End-User
   identifier discovery MUST accept both methods.  If the RDAP server
   supports a default Authorization Server or End-User identifier
   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":

   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 Authorization Server:

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

4.2.2.  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 Section 3.4 of
   RFC 3986 [RFC3986].  If the RDAP server supports a default
   Authorization Server, 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":

   https://example.com/rdap/farv1_session/
   login?farv1_iss=https%3A%2F%2Fidp.example.com

4.2.3.  Login Response

   The response to the login request MUST use the response structures
   specified in RFC 9083 [RFC9083].  In addition, the response MUST
   include an indication of the requested operation's success or failure
   in the "notices" data structure.  If successful, the response MUST
   include a "farv1_session" data structure that includes a "userClaims"
   object and a "sessionInfo" 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": {
           "clientID": "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

   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": {
           "clientID": "user.idp.example",
           "iss": "https://idp.example.com"
         }
       }

                                  Figure 5

4.2.4.  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
   traditional OAuth flow.  This method requires an End-User to use a
   second device (such as a smart telephone) that has access to a web
   browser for entry of a code sequence that is presented on the UI-
   constrained device.

4.2.4.1.  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 Authorization Servers, the "farv1_session/device" request MUST
   include either an End-User identifier as described in Section 4.2.1
   or an OP Issuer Identifier as described in Section 4.2.2.

   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 6

   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.

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   An example using curl and an authorization header:

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

                                  Figure 7

   The response to this request MUST use the response structures
   specified in RFC 9083 [RFC9083].  In addition, the response MUST
   include an indication of the requested operation's success or failure
   in the "notices" data structure, 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": {
         "verification_url": "https://www.example.com/device",
         "user_code": "NJJQ-GJFC",
         "device_code": "AH-1ng2ezu",
         "expires_in": 1800
       }
     }

                                  Figure 8

4.2.4.2.  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 performs the
   polling function described in RFC 8628 [RFC8628], allowing the RDAP
   server to wait for the End-User to enter the information returned
   from the "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 Authorization Servers, the

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   "farv1_session/devicepoll" request MUST include either an End-User
   identifier as described in Section 4.2.1 or an OP Issuer Identifier
   as described in Section 4.2.2.

   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.

   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 9

   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 10

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

4.3.  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 Section 3.4 of RFC 3986 [RFC3986].

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4.3.1.  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 3.1.4.1).  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

4.3.2.  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 501 (Not Implemented)
   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

4.4.  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

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   The response to this query MUST use the response structures specified
   in RFC 9083 [RFC9083].  In addition, the response MUST include an
   indication of the requested operation's success or failure in the
   "notices" data structure.  If the operation is successful, and an
   active session exists, the response MUST include a "farv1_session"
   data structure that includes a "userClaims" object and a
   "sessionInfo" 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:

     {
       "rdapConformance": [
         "farv1"
       ],
       "lang": "en-US",
       "notices": {
         "title": "Session Status Result",
         "description": [
           "Session status succeeded"
         ]
       },
       "farv1_session": {
         "clientID": "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
         }
       }
     }

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                                 Figure 11

   If the operation is successful, and an active session does not exist,
   the response MUST 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:

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

                                 Figure 12

4.5.  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 use the response structures
   specified in RFC 9083 [RFC9083].  In addition, the response MUST
   include an indication of the requested operation's success or failure
   in the "notices" data structure.  The response MUST include a
   "farv1_session" data structure that includes a "userClaims" object
   and a "sessionInfo" object.  If unsuccessful, but an active session
   exists, the response MUST include a "farv1_session" data structure

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   that includes a "userClaims" object and a "sessionInfo" 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:

     {
       "rdapConformance": [
         "farv1"
       ],
       "lang": "en-US",
       "notices": {
         "title": "Session Refresh Result",
         "description": [
           "Session refresh succeeded",
           "Token refresh succeeded."
         ]
       },
       "farv1_session": {
         "clientID": "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 13

   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

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   refresh.  The default RDAP server behavior is described in the
   "implicitTokenRefreshSupported" value that's included in the
   "farv1_openidcConfiguration" data structure (see Section 4.1.3).

   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.

   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 send an HTTP 409
   (Conflict) response if a "farv1_session/refresh" request is received
   in the absence of an active login session.

4.6.  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 logout from the OP using the "OpenID Connect RP-
   Initiated Logout" protocol ([OIDCL]) if that protocol is supported by
   the OP.

   An example "farv1_session/logout" request:

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

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

   An example of a "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 14

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

4.7.  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 501 (Not
   Implemented) response.  An RDAP server that receives a query
   containing identification information associated with a recognized OP
   MUST perform the steps required to authenticate the user with the OP,
   process the query, and return an RDAP response that is appropriate
   for the End-User's level of authorization and access.

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4.8.  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 any request that includes an unknown HTTP
   cookie, the server MUST return an HTTP 409 (Conflict) error.  If a
   client sends a "farv1_session/status", "farv1_session/refresh", or
   "farv1_session/logout" request in the absence of an active session,
   the server MUST return an HTTP 409 (Conflict) error.

5.  Token Exchange

   ID tokens 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" value that does not include the RP's
   client_id.  These tokens might not be trusted by the RP, and the RP
   might refuse to accept the tokens.  This situation can be remedied by
   having the RP exchange these tokens with the OP for a set of trusted
   tokens that reset the "aud" claim.  This token exchange protocol is
   described in RFC 8693 [RFC8693].  This issue is not visible to the
   RDAP client and should be managed by the OpenID implementation used
   by the RDAP server.

6.  RDAP Query Processing

   Once an RDAP session is active, an RDAP server MUST determine if the
   End-User is authorized to perform any queries that are received
   during the duration of the session.  This MAY include rejecting
   queries outright, and it MAY include omitting or otherwise redacting
   information that the End-User is not authorized to receive.  Specific
   processing requirements are beyond the scope of this document.  A
   client can end a session explicitly by sending a "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.

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7.  RDAP Conformance

   RDAP responses that contain values described in this document MUST
   indicate conformance with this specification by including an
   rdapConformance ([RFC9083]) value of "farv1" (Federated
   Authentication for RDAP version 1).  The information needed to
   register this value in the RDAP Extensions Registry is described in
   Section 8.1.

   Example rdapConformance structure with extension specified:

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

                                 Figure 15

8.  IANA Considerations

8.1.  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: IESG <iesg@ietf.org>
      Intended usage: This extension describes version 1 of a federated
      authentication method for RDAP using OAuth 2.0 and OpenID Connect.

8.2.  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"
      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: IESG
      Specification Document(s): Section 3.1.4.1 of this document.

      Claim Name: "rdap_dnt_allowed"

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      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: IESG
      Specification Document(s): Section 3.1.4.2 of this document.

8.3.  RDAP Query Purpose Registry

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

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

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

   Registration Procedure: Specification Required

   Reference: This document

   Required information: See Section 3.1.4.1.

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

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

   Initial assignments and reservations:

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

      Value: domainNameControl

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

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

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

      Value: personalDataProtection

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

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

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

      Value: technicalIssueResolution

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

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

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

      Value: domainNameCertification

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

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

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

      Value: individualInternetUse

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

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

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

      Value: businessDomainNamePurchaseOrSale

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

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

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

      Value: academicPublicInterestDNSRResearch

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

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

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

      Value: legalActions

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

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

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

      Value: regulatoryAndContractEnforcement

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

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

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

      Value: criminalInvestigationAndDNSAbuseMitigation

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

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

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

      Value: dnsTransparency

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

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

9.  Implementation Status

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

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

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

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

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9.1.  Editor Implementation

      Location: https://procuratus.net/rdap/
      Description: This implementation is a functionally limited RDAP
      server that supports only the path segments described in this
      specification.  It uses the "jumbojett/OpenID-Connect-PHP" library
      found on GitHub, which appears to 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

9.2.  Verisign Labs

      Responsible Organization: Verisign Labs
      Location: https://rdap.verisignlabs.com/
      Description: This implementation includes support for domain
      registry RDAP queries using live data from the .cc and .tv country
      code top-level domains and the .career generic top-level domain.
      Three access levels are provided based on the authenticated
      identity of the client:
      1.  Unauthenticated: Limited information is returned in response
          to queries from unauthenticated clients.
      2.  Basic: Clients who authenticate using a publicly available
          identity provider like Google Gmail or Microsoft Hotmail will
          receive all 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.
          Currently supported identity providers include those developed
          by Verisign Labs (https://testprovider.rdap.verisignlabs.com/)
          and CZ.NIC (https://www.mojeid.cz/).
      Level of Maturity: This is a "proof of concept" research
      implementation.
      Coverage: This implementation includes all the features described
      in this specification.
      Version compatibility: Version -07 of this specification.
      Contact Information: Scott Hollenbeck, shollenbeck@verisign.com

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9.3.  Viagenie

      Responsible Organization: Viagenie
      Location: https://auth.viagenie.ca
      Description: This implementation is an OpenID identity provider
      enabling users and registries to connect to the federation.  It
      also includes a barebone RDAP client and RDAP server in order to
      test the authentication framework.  Various 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

10.  Security Considerations

   Security considerations for RDAP can be found in RFC 7481 [RFC7481].
   Security considerations for OpenID Connect Core [OIDCC] and OAuth 2.0
   [RFC6749] can be found in their reference specifications.  OpenID
   Connect defines optional mechanisms for robust signing and encryption
   that can be used to provide data integrity and data confidentiality
   services as needed.  Additionally, the practices described in RFC
   8996 [RFC7481] MUST be followed when the Transport Layer Security
   (TLS) protocol is used.

10.1.  Authentication and Access Control

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

11.  Acknowledgments

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

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   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.

12.  References

12.1.  Normative References

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

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

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

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

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

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

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

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

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

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

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

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

   [RFC7480]  Newton, A., Ellacott, B., and N. Kong, "HTTP Usage in the
              Registration Data Access Protocol (RDAP)", RFC 7480,
              STD 95, 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)", RFC 7481,
              STD 95, 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)", DOI 10.17487/RFC7519, RFC 7519, May 2015,
              <https://www.rfc-editor.org/info/rfc7519>.

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

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

   [RFC8628]  Denniss, W., Bradley, J., Jones, M., and H. Tschofenig,
              "OAuth 2.0 Device Authorization Grant",
              DOI 10.17487/RFC8628, RFC 8628, 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",
              DOI 10.17487/RFC8693, RFC 8693, January 2020,
              <https://www.rfc-editor.org/info/rfc8693>.

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   [RFC8996]  Moriarty, K. and S. Farrell, "Deprecating TLS 1.0 and TLS
              1.1", BCP 195, DOI 10.17487/RFC8996, RFC 8996, March 2021,
              <https://www.rfc-editor.org/info/rfc8996>.

   [RFC9082]  Hollenbeck, S. and A. Newton, "Registration Data Access
              Protocol (RDAP) Query Format", RFC 9082, STD 95,
              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)", RFC 9083,
              STD 95, DOI 10.17487/RFC9083, June 2021,
              <https://www.rfc-editor.org/info/rfc9083>.

12.2.  Informative References

   [RFC4949]  Shirey, R., "Internet Security Glossary, Version 2",
              FYI 36, DOI 10.17487/RFC4949, RFC 4949, 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", DOI 10.17487/RFC8414,
              RFC 8414, June 2018,
              <https://www.rfc-editor.org/info/rfc8414>.

Appendix A.  Change Log

   00:  Initial working group version ported from draft-hollenbeck-
      regext-rdap-openid-10.
   01:  Modified ID Token delivery approach to note proper use of an
      HTTP bearer authorization header.
   02:  Modified token delivery approach (Access Token is the bearer
      token) to note proper use of an HTTP bearer authorization header,
      fixing the change made in -01.
   03:  Updated OAuth 2.0 Device Authorization Grant description and
      reference due to publication of RFC 8628.
   04:  Updated OAuth 2.0 token exchange description and reference due
      to publication of RFC 8693.  Corrected the RDAP conformance
      identifier to be registered with IANA.
   05:  Keepalive refresh.
   06:  Keepalive refresh.
   07:  Added "login_hint" description to Section 3.1.3.2.  Added some

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      text to Section 3.1.4.2 to note that "do not track" requires
      compliance with local regulations.
   08:  Rework of token management processing in Sections 4 and 5.
   09:  Updated RDAP specification references.  Added text to describe
      both default and remote Authorization Server processing.  Removed
      text that described passing of ID Tokens as query parameters.
   10:  Updated Section 3.1.3.1.  Replaced token processing queries with
      "login", "session", and "logout" queries.
   11:  Replaced queries with "session/*" queries.  Added description of
      "rdap" OAuth scope.  Added implementation status information.
   12:  Updated data structure descriptions.  Updated Section 8.  Minor
      formatting changes due to a move to xml2rfc-v3 markup.
   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 4.2.4.1.  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.

Author's Address

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

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