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Versions: (draft-sakimura-oauth-requrl) 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

OAuth Working Group                                          N. Sakimura
Internet-Draft                                            NAT.Consulting
Intended status: Standards Track                              J. Bradley
Expires: March 14, 2021                                           Yubico
                                                                M. Jones
                                                               Microsoft
                                                      September 10, 2020


The OAuth 2.0 Authorization Framework: JWT Secured Authorization Request
                                 (JAR)
                       draft-ietf-oauth-jwsreq-30

Abstract

   The authorization request in OAuth 2.0 described in RFC 6749 utilizes
   query parameter serialization, which means that Authorization Request
   parameters are encoded in the URI of the request and sent through
   user agents such as web browsers.  While it is easy to implement, it
   means that (a) the communication through the user agents is not
   integrity protected and thus the parameters can be tainted, and (b)
   the source of the communication is not authenticated.  Because of
   these weaknesses, several attacks to the protocol have now been put
   forward.

   This document introduces the ability to send request parameters in a
   JSON Web Token (JWT) instead, which allows the request to be signed
   with JSON Web Signature (JWS) and encrypted with JSON Web Encryption
   (JWE) so that the integrity, source authentication and
   confidentiality property of the Authorization Request is attained.
   The request can be sent by value or by reference.

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 March 14, 2021.



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Copyright Notice

   Copyright (c) 2020 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   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 Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   5
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   6
     2.1.  Request Object  . . . . . . . . . . . . . . . . . . . . .   6
     2.2.  Request Object URI  . . . . . . . . . . . . . . . . . . .   6
   3.  Symbols and abbreviated terms . . . . . . . . . . . . . . . .   6
   4.  Request Object  . . . . . . . . . . . . . . . . . . . . . . .   7
   5.  Authorization Request . . . . . . . . . . . . . . . . . . . .   9
     5.1.  Passing a Request Object by Value . . . . . . . . . . . .  10
     5.2.  Passing a Request Object by Reference . . . . . . . . . .  10
       5.2.1.  URI Referencing the Request Object  . . . . . . . . .  11
       5.2.2.  Request using the "request_uri" Request Parameter . .  12
       5.2.3.  Authorization Server Fetches Request Object . . . . .  12
   6.  Validating JWT-Based Requests . . . . . . . . . . . . . . . .  13
     6.1.  JWE Encrypted Request Object  . . . . . . . . . . . . . .  13
     6.2.  JWS Signed Request Object . . . . . . . . . . . . . . . .  13
     6.3.  Request Parameter Assembly and Validation . . . . . . . .  14
   7.  Authorization Server Response . . . . . . . . . . . . . . . .  14
   8.  TLS Requirements  . . . . . . . . . . . . . . . . . . . . . .  14
   9.  IANA  Considerations  . . . . . . . . . . . . . . . . . . . .  15
     9.1.  OAuth Parameters Registration . . . . . . . . . . . . . .  15
     9.2.  OAuth Authorization Server Metadata Registry  . . . . . .  16
     9.3.  OAuth Dynamic Client Registration Metadata Registry . . .  16
     9.4.  Media Type Registration . . . . . . . . . . . . . . . . .  17
       9.4.1.  Registry Contents . . . . . . . . . . . . . . . . . .  17
   10. Security Considerations . . . . . . . . . . . . . . . . . . .  18
     10.1.  Choice of Algorithms . . . . . . . . . . . . . . . . . .  18
     10.2.  Request Source Authentication  . . . . . . . . . . . . .  18
     10.3.  Explicit Endpoints . . . . . . . . . . . . . . . . . . .  19
     10.4.  Risks Associated with request_uri  . . . . . . . . . . .  19
       10.4.1.  DDoS Attack on the Authorization Server  . . . . . .  20



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       10.4.2.  Request URI Rewrite  . . . . . . . . . . . . . . . .  20
     10.5.  Downgrade Attack . . . . . . . . . . . . . . . . . . . .  20
     10.6.  TLS Security Considerations  . . . . . . . . . . . . . .  21
     10.7.  Parameter Mismatches . . . . . . . . . . . . . . . . . .  21
     10.8.  Cross-JWT Confusion  . . . . . . . . . . . . . . . . . .  21
   11. Privacy Considerations  . . . . . . . . . . . . . . . . . . .  22
     11.1.  Collection limitation  . . . . . . . . . . . . . . . . .  22
     11.2.  Disclosure Limitation  . . . . . . . . . . . . . . . . .  23
       11.2.1.  Request Disclosure . . . . . . . . . . . . . . . . .  23
       11.2.2.  Tracking using Request Object URI  . . . . . . . . .  23
   12. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  23
   13. Revision History  . . . . . . . . . . . . . . . . . . . . . .  24
   14. References  . . . . . . . . . . . . . . . . . . . . . . . . .  31
     14.1.  Normative References . . . . . . . . . . . . . . . . . .  31
     14.2.  Informative References . . . . . . . . . . . . . . . . .  33
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  35

1.  Introduction

   The Authorization Request in OAuth 2.0 [RFC6749] utilizes query
   parameter serialization and is typically sent through user agents
   such as web browsers.

   For example, the parameters "response_type", "client_id", "state",
   and "redirect_uri" are encoded in the URI of the request:

       GET /authorize?response_type=code&client_id=s6BhdRkqt3&state=xyz
       &redirect_uri=https%3A%2F%2Fclient%2Eexample%2Ecom%2Fcb HTTP/1.1
       Host: server.example.com

   While it is easy to implement, the encoding in the URI does not allow
   application layer security to be used to provide confidentiality and
   integrity protection.  While TLS is used to offer communication
   security between the Client and the user-agent as well as the user-
   agent and the Authorization Server, TLS sessions are terminated in
   the user-agent.  In addition, TLS sessions may be terminated
   prematurely at some middlebox (such as a load balancer).

   As the result, the Authorization Request of [RFC6749] has
   shortcomings in that:

   (a)  the communication through the user agents is not integrity
        protected and thus the parameters can be tainted (integrity
        protection failure)

   (b)  the source of the communication is not authenticated (source
        authentication failure)




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   (c)  the communication through the user agents can be monitored
        (containment / confidentiality failure).

   Due to these inherent weaknesses, several attacks against the
   protocol, such as Redirection URI rewriting and Mix-up attack [FETT],
   have been identified.

   The use of application layer security mitigates these issues.

   The use of application layer security allows requests to be prepared
   by a third party so that a client application cannot request more
   permissions than previously agreed.  This offers an additional degree
   of privacy protection.

   Furthermore, passing the request by reference allows the reduction of
   over-the-wire overhead.

   The JWT [RFC7519] encoding has been chosen because of

   (1)  its close relationship with JSON, which is used as OAuth's
        response format

   (2)  its developer friendliness due to its textual nature

   (3)  its relative compactness compared to XML

   (4)  its development status as a Proposed Standard, along with the
        associated signing and encryption methods [RFC7515] [RFC7516]

   (5)  the relative ease of JWS and JWE compared to XML Signature and
        Encryption.

   The parameters "request" and "request_uri" are introduced as
   additional authorization request parameters for the OAuth 2.0
   [RFC6749] flows.  The "request" parameter is a JSON Web Token (JWT)
   [RFC7519] whose JWT Claims Set holds the JSON encoded OAuth 2.0
   authorization request parameters.  Note that, in contrast to RFC
   7519, the elements of the Claims Set are encoded OAuth Request
   Parameters [IANA.OAuth.Parameters], supplemented with only a few of
   the IANA-managed JSON Web Token Claims [IANA.JWT.Claims] - in
   particular "iss" and "aud".  The JWT in the "request" parameter is
   integrity protected and source authenticated using JWS.

   The JWT [RFC7519] can be passed to the authorization endpoint by
   reference, in which case the parameter "request_uri" is used instead
   of the "request".





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   Using JWT [RFC7519] as the request encoding instead of query
   parameters has several advantages:

   (a)  (integrity protection) The request can be signed so that the
        integrity of the request can be checked.

   (b)  (source authentication) The request can be signed so that the
        signer can be authenticated.

   (c)  (confidentiality protection) The request can be encrypted so
        that end-to-end confidentiality can be provided even if the TLS
        connection is terminated at one point or another (including at
        and before user-agents).

   (d)  (collection minimization) The request can be signed by a third
        party attesting that the authorization request is compliant with
        a certain policy.  For example, a request can be pre-examined by
        a third party that all the personal data requested is strictly
        necessary to perform the process that the end-user asked for,
        and signed by that third party.  The authorization server then
        examines the signature and shows the conformance status to the
        end-user, who would have some assurance as to the legitimacy of
        the request when authorizing it.  In some cases, it may even be
        desirable to skip the authorization dialogue under such
        circumstances.

   There are a few cases that request by reference is useful such as:

   1.  When it is desirable to reduce the size of transmitted request.
       The use of application layer security increases the size of the
       request, particularly when public key cryptography is used.

   2.  When the client does not want to do the application level
       cryptography.  The Authorization Server may provide an endpoint
       to accept the Authorization Request through direct communication
       with the Client so that the Client is authenticated and the
       channel is TLS protected.

   This capability is in use by OpenID Connect [OpenID.Core].

1.1.  Requirements Language

   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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2.  Terminology

   For the purposes of this specification, the following terms and
   definitions in addition to what is defined in OAuth 2.0 Framework
   [RFC6749], JSON Web Signature [RFC7515], and JSON Web Encryption
   [RFC7519] apply.

2.1.  Request Object

   JSON Web Token (JWT) [RFC7519] whose JWT Claims Set holds the JSON
   encoded OAuth 2.0 authorization request parameters.

2.2.  Request Object URI

   Absolute URI that references the set of parameters comprising an
   OAuth 2.0 authorization request.  The contents of the resource
   referenced by the URI are a Request Object (Section 2.1), unless the
   URI was provided to the client by the same Authorization Server, in
   which case the content is an implementation detail at the discretion
   the Authorization Server.  The former is to ensure interoperability
   in cases where the provider of the request_uri is a separate entity
   from the consumer, such as when a client provides a URI referencing a
   Request Object stored on the client's backend service and made
   accessible via HTTPS.  In the latter case where the Authorization
   Server is both provider and consumer of the URI, such as when it
   offers an endpoint that provides a URI in exchange for a Request
   Object, this interoperability concern does not apply.

3.  Symbols and abbreviated terms

   The following abbreviations are common to this specification.

   JSON  JavaScript Object Notation

   JWT  JSON Web Token

   JWS  JSON Web Signature

   JWE  JSON Web Encryption

   URI  Uniform Resource Identifier

   URL  Uniform Resource Locator








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4.  Request Object

   A Request Object (Section 2.1) is used to provide authorization
   request parameters for an OAuth 2.0 authorization request.  It MUST
   contain all the parameters (including extension parameters) used to
   process the OAuth 2.0 [RFC6749] authorization request except the
   "request" and "request_uri" parameters that are defined in this
   document.  The parameters are represented as the JWT claims of the
   object.  Parameter names and string values MUST be included as JSON
   strings.  Since Request Objects are handled across domains and
   potentially outside of a closed ecosystem, per section 8.1 of
   [RFC8259], these JSON strings MUST be encoded using UTF-8 [RFC3629].
   Numerical values MUST be included as JSON numbers.  It MAY include
   any extension parameters.  This JSON [RFC7159] object constitutes the
   JWT Claims Set defined in JWT [RFC7519].  The JWT Claims Set is then
   signed or signed and encrypted.

   To sign, JSON Web Signature (JWS) [RFC7515] is used.  The result is a
   JWS signed JWT [RFC7519].  If signed, the Authorization Request
   Object SHOULD contain the Claims "iss" (issuer) and "aud" (audience)
   as members, with their semantics being the same as defined in the JWT
   [RFC7519] specification.  The value of "aud" should be the value of
   the Authorization Server (AS) "issuer" as defined in RFC8414
   [RFC8414].

   To encrypt, JWE [RFC7516] is used.  When both signature and
   encryption are being applied, the JWT MUST be signed then encrypted
   as described in Section 11.2 of [RFC7519].  The result is a Nested
   JWT, as defined in [RFC7519].

   The client determines the algorithms used to sign and encrypt Request
   Objects.  The algorithms chosen need to be supported by both the
   client and the authorization server.  The client can inform the
   authorization server of the algorithms that it supports in its
   dynamic client registration metadata [RFC7591], specifically, the
   metadata values "request_object_signing_alg",
   "request_object_encryption_alg", and "request_object_encryption_enc".
   Likewise, the authorization server can inform the client of the
   algorithms that it supports in its authorization server metadata
   [RFC8414], specifically, the metadata values
   "request_object_signing_alg_values_supported",
   "request_object_encryption_alg_values_supported", and
   "request_object_encryption_enc_values_supported".

   The Request Object MAY be sent by value as described in Section 5.1
   or by reference as described in Section 5.2.  "request" and
   "request_uri" parameters MUST NOT be included in Request Objects.




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   A Request Object (Section 2.1) has the "mime-type" "application/
   oauth-authz-req+jwt".  Note that some existing deployments may
   alternatively be using the type "application/jwt".

   The following is an example of the Claims in a Request Object before
   base64url encoding and signing.  Note that it includes the extension
   parameters "nonce" and "max_age".

     {
      "iss": "s6BhdRkqt3",
      "aud": "https://server.example.com",
      "response_type": "code id_token",
      "client_id": "s6BhdRkqt3",
      "redirect_uri": "https://client.example.org/cb",
      "scope": "openid",
      "state": "af0ifjsldkj",
      "nonce": "n-0S6_WzA2Mj",
      "max_age": 86400
     }

   Signing it with the "RS256" algorithm results in this Request Object
   value (with line wraps within values for display purposes only):

     eyJhbGciOiJSUzI1NiIsImtpZCI6ImsyYmRjIn0.ewogICAgImlzcyI6ICJzNkJoZF
     JrcXQzIiwKICAgICJhdWQiOiAiaHR0cHM6Ly9zZXJ2ZXIuZXhhbXBsZS5jb20iLAog
     ICAgInJlc3BvbnNlX3R5cGUiOiAiY29kZSBpZF90b2tlbiIsCiAgICAiY2xpZW50X2
     lkIjogInM2QmhkUmtxdDMiLAogICAgInJlZGlyZWN0X3VyaSI6ICJodHRwczovL2Ns
     aWVudC5leGFtcGxlLm9yZy9jYiIsCiAgICAic2NvcGUiOiAib3BlbmlkIiwKICAgIC
     JzdGF0ZSI6ICJhZjBpZmpzbGRraiIsCiAgICAibm9uY2UiOiAibi0wUzZfV3pBMk1q
     IiwKICAgICJtYXhfYWdlIjogODY0MDAKfQ.Nsxa_18VUElVaPjqW_ToI1yrEJ67BgK
     b5xsuZRVqzGkfKrOIX7BCx0biSxYGmjK9KJPctH1OC0iQJwXu5YVY-vnW0_PLJb1C2
     HG-ztVzcnKZC2gE4i0vgQcpkUOCpW3SEYXnyWnKzuKzqSb1wAZALo5f89B_p6QA6j6
     JwBSRvdVsDPdulW8lKxGTbH82czCaQ50rLAg3EYLYaCb4ik4I1zGXE4fvim9FIMs8O
     CMmzwIB5S-ujFfzwFjoyuPEV4hJnoVUmXR_W9typPf846lGwA8h9G9oNTIuX8Ft2jf
     pnZdFmLg3_wr3Wa5q3a-lfbgF3S9H_8nN3j1i7tLR_5Nz-g
















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   The following RSA public key, represented in JWK format, can be used
   to validate the Request Object signature in this and subsequent
   Request Object examples (with line wraps within values for display
   purposes only):

     {
      "kty":"RSA",
      "kid":"k2bdc",
      "n":"x5RbkAZkmpRxia65qRQ1wwSMSxQUnS7gcpVTV_cdHmfmG2ltd2yabEO9XadD8
           pJNZubINPpmgHh3J1aD9WRwS05ucmFq3CfFsluLt13_7oX5yDRSKX7poXmT_5
           ko8k4NJZPMAO8fPToDTH7kHYbONSE2FYa5GZ60CUsFhSonI-dcMDJ0Ary9lxI
           w5k2z4TAdARVWcS7sD07VhlMMshrwsPHBQgTatlkxyIHXbYdtak8fqvNAwr7O
           lVEvM_Ipf5OfmdB8Sd-wjzaBsyP4VhJKoi_qdgSzpC694XZeYPq45Sw-q51iF
           UlcOlTCI7z6jltUtnR6ySn6XDGFnzH5Fe5ypw",
      "e":"AQAB"
     }

5.  Authorization Request

   The client constructs the authorization request URI by adding the
   following parameters to the query component of the authorization
   endpoint URI using the "application/x-www-form-urlencoded" format:

   request
      REQUIRED unless "request_uri" is specified.  The Request Object
      (Section 2.1) that holds authorization request parameters stated
      in section 4 of OAuth 2.0 [RFC6749].  If this parameter is present
      in the authorization request, "request_uri" MUST NOT be present.

   request_uri
      REQUIRED unless "request" is specified.  The absolute URI as
      defined by RFC3986 [RFC3986] that is the Request Object URI
      (Section 2.2) referencing the authorization request parameters
      stated in section 4 of OAuth 2.0 [RFC6749].  If this parameter is
      present in the authorization request, "request" MUST NOT be
      present.

   client_id
      REQUIRED.  OAuth 2.0 [RFC6749] "client_id".  The value MUST match
      the "request" or "request_uri" Request Object's (Section 2.1)
      "client_id".

   The client directs the resource owner to the constructed URI using an
   HTTP redirection response, or by other means available to it via the
   user-agent.

   For example, the client directs the end user's user-agent to make the
   following HTTPS request:



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   GET /authz?client_id=s6BhdRkqt3&request=eyJhbG..AlMGzw HTTP/1.1
   Host: server.example.com

   The value for the request parameter is abbreviated for brevity.

   The authorization request object MUST be one of the following:

   (a)  JWS signed

   (b)  JWS signed and JWE encrypted

   The client MAY send the parameters included in the request object
   duplicated in the query parameters as well for the backward
   compatibility etc.  However, the authorization server supporting this
   specification MUST only use the parameters included in the request
   object.

5.1.  Passing a Request Object by Value

   The Client sends the Authorization Request as a Request Object to the
   Authorization Endpoint as the "request" parameter value.

   The following is an example of an Authorization Request using the
   "request" parameter (with line wraps within values for display
   purposes only):

     https://server.example.com/authorize?client_id=s6BhdRkqt3&
       request=eyJhbGciOiJSUzI1NiIsImtpZCI6ImsyYmRjIn0.ewogICAgImlzcyI6
       ICJzNkJoZFJrcXQzIiwKICAgICJhdWQiOiAiaHR0cHM6Ly9zZXJ2ZXIuZXhhbXBs
       ZS5jb20iLAogICAgInJlc3BvbnNlX3R5cGUiOiAiY29kZSBpZF90b2tlbiIsCiAg
       ICAiY2xpZW50X2lkIjogInM2QmhkUmtxdDMiLAogICAgInJlZGlyZWN0X3VyaSI6
       ICJodHRwczovL2NsaWVudC5leGFtcGxlLm9yZy9jYiIsCiAgICAic2NvcGUiOiAi
       b3BlbmlkIiwKICAgICJzdGF0ZSI6ICJhZjBpZmpzbGRraiIsCiAgICAibm9uY2Ui
       OiAibi0wUzZfV3pBMk1qIiwKICAgICJtYXhfYWdlIjogODY0MDAKfQ.Nsxa_18VU
       ElVaPjqW_ToI1yrEJ67BgKb5xsuZRVqzGkfKrOIX7BCx0biSxYGmjK9KJPctH1OC
       0iQJwXu5YVY-vnW0_PLJb1C2HG-ztVzcnKZC2gE4i0vgQcpkUOCpW3SEYXnyWnKz
       uKzqSb1wAZALo5f89B_p6QA6j6JwBSRvdVsDPdulW8lKxGTbH82czCaQ50rLAg3E
       YLYaCb4ik4I1zGXE4fvim9FIMs8OCMmzwIB5S-ujFfzwFjoyuPEV4hJnoVUmXR_W
       9typPf846lGwA8h9G9oNTIuX8Ft2jfpnZdFmLg3_wr3Wa5q3a-lfbgF3S9H_8nN3
       j1i7tLR_5Nz-g

5.2.  Passing a Request Object by Reference

   The "request_uri" Authorization Request parameter enables OAuth
   authorization requests to be passed by reference, rather than by
   value.  This parameter is used identically to the "request"
   parameter, other than that the Request Object value is retrieved from




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   the resource identified by the specified URI rather than passed by
   value.

   The entire Request URI MUST NOT exceed 512 ASCII characters.  There
   are three reasons for this restriction.

   1.  Many phones in the market as of this writing still do not accept
       large payloads.  The restriction is typically either 512 or 1024
       ASCII characters.

   2.  On a slow connection such as 2G mobile connection, a large URL
       would cause the slow response and therefore the use of such is
       not advisable from the user experience point of view.

   The contents of the resource referenced by the "request_uri" MUST be
   a Request Object and MUST be reachable by the Authorization Server
   unless the URI was provided to the client by the Authorization
   Server.  In the first case, the "request_uri" MUST be an "https" URI,
   as specified in Section 2.7.2 of RFC7230 [RFC7230].  In the second
   case, it MUST be a URN, as specified in RFC8141 [RFC8141].

   The following is an example of the contents of a Request Object
   resource that can be referenced by a "request_uri" (with line wraps
   within values for display purposes only):

     eyJhbGciOiJSUzI1NiIsImtpZCI6ImsyYmRjIn0.ewogICAgImlzcyI6ICJzNkJoZF
     JrcXQzIiwKICAgICJhdWQiOiAiaHR0cHM6Ly9zZXJ2ZXIuZXhhbXBsZS5jb20iLAog
     ICAgInJlc3BvbnNlX3R5cGUiOiAiY29kZSBpZF90b2tlbiIsCiAgICAiY2xpZW50X2
     lkIjogInM2QmhkUmtxdDMiLAogICAgInJlZGlyZWN0X3VyaSI6ICJodHRwczovL2Ns
     aWVudC5leGFtcGxlLm9yZy9jYiIsCiAgICAic2NvcGUiOiAib3BlbmlkIiwKICAgIC
     JzdGF0ZSI6ICJhZjBpZmpzbGRraiIsCiAgICAibm9uY2UiOiAibi0wUzZfV3pBMk1q
     IiwKICAgICJtYXhfYWdlIjogODY0MDAKfQ.Nsxa_18VUElVaPjqW_ToI1yrEJ67BgK
     b5xsuZRVqzGkfKrOIX7BCx0biSxYGmjK9KJPctH1OC0iQJwXu5YVY-vnW0_PLJb1C2
     HG-ztVzcnKZC2gE4i0vgQcpkUOCpW3SEYXnyWnKzuKzqSb1wAZALo5f89B_p6QA6j6
     JwBSRvdVsDPdulW8lKxGTbH82czCaQ50rLAg3EYLYaCb4ik4I1zGXE4fvim9FIMs8O
     CMmzwIB5S-ujFfzwFjoyuPEV4hJnoVUmXR_W9typPf846lGwA8h9G9oNTIuX8Ft2jf
     pnZdFmLg3_wr3Wa5q3a-lfbgF3S9H_8nN3j1i7tLR_5Nz-g

5.2.1.  URI Referencing the Request Object

   The Client stores the Request Object resource either locally or
   remotely at a URI the Authorization Server can access.  Such facility
   may be provided by the authorization server or a third party.  For
   example, the authorization server may provide a URL to which the
   client POSTs the request object and obtains the Request URI.  This
   URI is the Request Object URI, "request_uri".





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   It is possible for the Request Object to include values that are to
   be revealed only to the Authorization Server.  As such, the
   "request_uri" MUST have appropriate entropy for its lifetime so that
   the URI is not guessable if publicly retrievable.  For the guidance,
   refer to 5.1.4.2.2 of [RFC6819] and Good Practices for Capability
   URLs [CapURLs].  It is RECOMMENDED that it be removed after a
   reasonable timeout unless access control measures are taken.

   The following is an example of a Request Object URI value (with line
   wraps within values for display purposes only).  In this example, a
   third-party Trust Framework Provider (TFP) hosts the Request Object.

     https://tfp.example.org/request.jwt/
       GkurKxf5T0Y-mnPFCHqWOMiZi4VS138cQO_V7PZHAdM

5.2.2.  Request using the "request_uri" Request Parameter

   The Client sends the Authorization Request to the Authorization
   Endpoint.

   The following is an example of an Authorization Request using the
   "request_uri" parameter (with line wraps within values for display
   purposes only):

     https://server.example.com/authorize?
       client_id=s6BhdRkqt3
       &request_uri=https%3A%2F%2Ftfp.example.org%2Frequest.jwt
       %2FGkurKxf5T0Y-mnPFCHqWOMiZi4VS138cQO_V7PZHAdM

5.2.3.  Authorization Server Fetches Request Object

   Upon receipt of the Request, the Authorization Server MUST send an
   HTTP "GET" request to the "request_uri" to retrieve the referenced
   Request Object, unless it is stored in a way so that it can retrieve
   it through other mechanism securely, and parse it to recreate the
   Authorization Request parameters.

   The following is an example of this fetch process.  In this example,
   a third-party Trust Framework Provider (TFP) hosts the Request
   Object.

   GET /request.jwt/GkurKxf5T0Y-mnPFCHqWOMiZi4VS138cQO_V7PZHAdM HTTP/1.1
   Host: tfp.example.org








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   The following is an example of the fetch response:

     HTTP/1.1 200 OK
     Date: Thu, 20 Aug 2020 23:52:39 GMT
     Server: Apache/2.4.43 (tfp.example.org)
     Content-type: application/oauth-authz-req+jwt
     Content-Length: 797
     Last-Modified: Wed, 19 Aug 2020 23:52:32 GMT

     eyJhbGciOiJSUzI1NiIsImtpZCI6ImsyYmRjIn0.ewogICAgImlzcyI6ICJzNkJoZF
     JrcXQzIiwKICAgICJhdWQiOiAiaHR0cHM6Ly9zZXJ2ZXIuZXhhbXBsZS5jb20iLAog
     ICAgInJlc3BvbnNlX3R5cGUiOiAiY29kZSBpZF90b2tlbiIsCiAgICAiY2xpZW50X2
     lkIjogInM2QmhkUmtxdDMiLAogICAgInJlZGlyZWN0X3VyaSI6ICJodHRwczovL2Ns
     aWVudC5leGFtcGxlLm9yZy9jYiIsCiAgICAic2NvcGUiOiAib3BlbmlkIiwKICAgIC
     JzdGF0ZSI6ICJhZjBpZmpzbGRraiIsCiAgICAibm9uY2UiOiAibi0wUzZfV3pBMk1q
     IiwKICAgICJtYXhfYWdlIjogODY0MDAKfQ.Nsxa_18VUElVaPjqW_ToI1yrEJ67BgK
     b5xsuZRVqzGkfKrOIX7BCx0biSxYGmjK9KJPctH1OC0iQJwXu5YVY-vnW0_PLJb1C2
     HG-ztVzcnKZC2gE4i0vgQcpkUOCpW3SEYXnyWnKzuKzqSb1wAZALo5f89B_p6QA6j6
     JwBSRvdVsDPdulW8lKxGTbH82czCaQ50rLAg3EYLYaCb4ik4I1zGXE4fvim9FIMs8O
     CMmzwIB5S-ujFfzwFjoyuPEV4hJnoVUmXR_W9typPf846lGwA8h9G9oNTIuX8Ft2jf
     pnZdFmLg3_wr3Wa5q3a-lfbgF3S9H_8nN3j1i7tLR_5Nz-g

6.  Validating JWT-Based Requests

6.1.  JWE Encrypted Request Object

   If the request object is encrypted, the Authorization Server MUST
   decrypt the JWT in accordance with the JSON Web Encryption [RFC7516]
   specification.

   The result is a signed request object.

   If decryption fails, the Authorization Server MUST return an
   "invalid_request_object" error.

6.2.  JWS Signed Request Object

   The Authorization Server MUST validate the signature of the JSON Web
   Signature [RFC7515] signed Request Object.  The signature MUST be
   validated using the key for that "client_id" and the algorithm
   specified in the "alg" Header Parameter.

   If signature validation fails, the Authorization Server MUST return
   an "invalid_request_object" error.







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6.3.  Request Parameter Assembly and Validation

   The Authorization Server MUST extract the set of Authorization
   Request parameters from the Request Object value.  The Authorization
   Server MUST only use the parameters in the Request Object even if the
   same parameter is provided in the query parameter.  The Client ID
   values in the "client_id" request parameter and in the Request Object
   "client_id" claim MUST be identical.  The Authorization Server then
   validates the request as specified in OAuth 2.0 [RFC6749].

   If the validation fails, then the Authorization Server MUST return an
   error as specified in OAuth 2.0 [RFC6749].

7.  Authorization Server Response

   Authorization Server Response is created and sent to the client as in
   Section 4 of OAuth 2.0 [RFC6749].

   In addition, this document uses these additional error values:

   invalid_request_uri
      The "request_uri" in the Authorization Request returns an error or
      contains invalid data.

   invalid_request_object
      The request parameter contains an invalid Request Object.

   request_not_supported
      The Authorization Server does not support the use of the "request"
      parameter.

   request_uri_not_supported
      The Authorization Server does not support the use of the
      "request_uri" parameter.

8.  TLS Requirements

   Client implementations supporting the Request Object URI method MUST
   support TLS following Recommendations for Secure Use of Transport
   Layer Security (TLS) and Datagram Transport Layer Security (DTLS)
   [BCP195].

   To protect against information disclosure and tampering,
   confidentiality protection MUST be applied using TLS with a cipher
   suite that provides confidentiality and integrity protection.

   HTTP clients MUST also verify the TLS server certificate, using DNS-
   ID [RFC6125], to avoid man-in-the-middle attacks.  The rules and



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   guidelines defined in [RFC6125] apply here, with the following
   considerations:

   o  Support for DNS-ID identifier type (that is, the dNSName identity
      in the subjectAltName extension) is REQUIRED.  Certification
      authorities which issue server certificates MUST support the DNS-
      ID identifier type, and the DNS-ID identifier type MUST be present
      in server certificates.

   o  DNS names in server certificates MAY contain the wildcard
      character "*".

   o  Clients MUST NOT use CN-ID identifiers; a CN field may be present
      in the server certificate's subject name, but MUST NOT be used for
      authentication within the rules described in [BCP195].

   o  SRV-ID and URI-ID as described in Section 6.5 of [RFC6125] MUST
      NOT be used for comparison.

9.  IANA Considerations

9.1.  OAuth Parameters Registration

   Since the request object is a JWT, the core JWT claims cannot be used
   for any purpose in the request object other than for what JWT
   dictates.  Thus, they need to be registered as OAuth Authorization
   Request parameters to avoid future OAuth extensions using them with
   different meanings.

   This specification adds the following values to the "OAuth
   Parameters" registry [IANA.OAuth.Parameters] established by
   [RFC6749].

   o  Name: "iss"
   o  Parameter Usage Location: authorization request
   o  Change Controller: IETF
   o  Specification Document(s): Section 4.1.1 of [RFC7519] and this
      document.

   o  Name: "sub"
   o  Parameter Usage Location: authorization request
   o  Change Controller: IETF
   o  Specification Document(s): Section 4.1.2 of [RFC7519] and this
      document.

   o  Name: "aud"
   o  Parameter Usage Location: authorization request
   o  Change Controller: IETF



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   o  Specification Document(s): Section 4.1.3 of [RFC7519] and this
      document.

   o  Name: "exp"
   o  Parameter Usage Location: authorization request
   o  Change Controller: IETF
   o  Specification Document(s): Section 4.1.4 of [RFC7519] and this
      document.

   o  Name: "nbf"
   o  Parameter Usage Location: authorization request
   o  Change Controller: IETF
   o  Specification Document(s): Section 4.1.5 of [RFC7519] and this
      document.

   o  Name: "iat"
   o  Parameter Usage Location: authorization request
   o  Change Controller: IETF
   o  Specification Document(s): Section 4.1.6 of [RFC7519] and this
      document.

   o  Name: "jti"
   o  Parameter Usage Location: authorization request
   o  Change Controller: IETF
   o  Specification Document(s): Section 4.1.7 of [RFC7519] and this
      document.

9.2.  OAuth Authorization Server Metadata Registry

   This specification adds the following values to the "OAuth
   Authorization Server Metadata" registry [IANA.OAuth.Parameters]
   established by [RFC8414].

   o  Metadata Name: "require_signed_request_object"
   o  Metadata Description: Indicates where authorization request needs
      to be protected as Request Object and provided through either
      "request" or "request_uri parameter".
   o  Change Controller: IETF
   o  Specification Document(s): Section 10.5 of this document.

9.3.  OAuth Dynamic Client Registration Metadata Registry

   This specification adds the following values to the "OAuth Dynamic
   Client Registration Metadata" registry [IANA.OAuth.Parameters]
   established by [RFC7591].

   o  Metadata Name: "require_signed_request_object"




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   o  Metadata Description: Indicates where authorization request needs
      to be protected as Request Object and provided through either
      "request" or "request_uri parameter".
   o  Change Controller: IETF
   o  Specification Document(s): Section 10.5 of this document.

9.4.  Media Type Registration

9.4.1.  Registry Contents

   This section registers the "application/oauth-authz-req+jwt" media
   type [RFC2046] in the "Media Types" registry [IANA.MediaTypes] in the
   manner described in [RFC6838], which can be used to indicate that the
   content is a JWT containing Request Object claims.

   o  Type name: application
   o  Subtype name: oauth-authz-req+jwt
   o  Required parameters: n/a
   o  Optional parameters: n/a
   o  Encoding considerations: binary; A Request Object is a JWT; JWT
      values are encoded as a series of base64url-encoded values (some
      of which may be the empty string) separated by period ('.')
      characters.
   o  Security considerations: See Section 10 of [[ this specification
      ]]
   o  Interoperability considerations: n/a
   o  Published specification: Section 4 of [[ this specification ]]
   o  Applications that use this media type: Applications that use
      Request Objects to make an OAuth 2.0 Authorization Request
   o  Fragment identifier considerations: n/a
   o  Additional information:

         Magic number(s): n/a
         File extension(s): n/a
         Macintosh file type code(s): n/a

   o  Person & email address to contact for further information:
      Nat Sakimura, nat@nat.consulting
   o  Intended usage: COMMON
   o  Restrictions on usage: none
   o  Author: Nat Sakimura, nat@nat.consulting
   o  Change controller: IETF
   o  Provisional registration?  No








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10.  Security Considerations

   In addition to the all the security considerations discussed in OAuth
   2.0 [RFC6819], the security considerations in [RFC7515], [RFC7516],
   [RFC7518], and [RFC8725] need to be considered.  Also, there are
   several academic papers such as [BASIN] that provide useful insight
   into the security properties of protocols like OAuth.

   In consideration of the above, this document advises taking the
   following security considerations into account.

10.1.  Choice of Algorithms

   When sending the authorization request object through "request"
   parameter, it MUST either be signed using JWS [RFC7515] or signed
   then encrypted using JWS [RFC7515] and JWE [RFC7516] respectively,
   with then considered appropriate algorithms.

10.2.  Request Source Authentication

   The source of the Authorization Request MUST always be verified.
   There are several ways to do it:

   (a)  Verifying the JWS Signature of the Request Object.

   (b)  Verifying that the symmetric key for the JWE encryption is the
        correct one if the JWE is using symmetric encryption.

   (c)  Verifying the TLS Server Identity of the Request Object URI.  In
        this case, the Authorization Server MUST know out-of-band that
        the Client uses Request Object URI and only the Client is
        covered by the TLS certificate.  In general, it is not a
        reliable method.

   (d)  When an Authorization Server implements a service that returns a
        Request Object URI in exchange for a Request Object, the
        Authorization Server MUST perform Client Authentication to
        accept the Request Object and bind the Client Identifier to the
        Request Object URI it is providing.  It MUST validate the
        signature, per (a).  Since Request Object URI can be replayed,
        the lifetime of the Request Object URI MUST be short and
        preferably one-time use.  The entropy of the Request Object URI
        MUST be sufficiently large.  The adequate shortness of the
        validity and the entropy of the Request Object URI depends on
        the risk calculation based on the value of the resource being
        protected.  A general guidance for the validity time would be
        less than a minute and the Request Object URI is to include a




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        cryptographic random value of 128bit or more at the time of the
        writing of this specification.

   (e)  When a third party, such as a Trust Framework Provider(TFP),
        implements a service that returns a Request Object URI in
        exchange for a Request Object, it MUST validate the signature,
        per (a).  In addition, the Authorization Server MUST be a member
        of the trust framework and MUST know out-of-band that the client
        also uses the trust framework.

10.3.  Explicit Endpoints

   Although this specification does not require them, research such as
   [BASIN] points out that it is a good practice to explicitly state the
   intended interaction endpoints and the message position in the
   sequence in a tamper evident manner so that the intent of the
   initiator is unambiguous.  The following endpoints defined in
   [RFC6749], [RFC6750], and [RFC8414] are RECOMMENDED by this
   specification to use this practice :

   (a)  Protected Resources ("protected_resources")

   (b)  Authorization Endpoint ("authorization_endpoint")

   (c)  Redirection URI ("redirect_uri")

   (d)  Token Endpoint ("token_endpoint")

   Further, if dynamic discovery is used, then this practice also
   applies to the discovery related endpoints.

   In [RFC6749], while Redirection URI is included in the Authorization
   Request, others are not.  As a result, the same applies to
   Authorization Request Object.

   The lack of linkage among those endpoints is cited as the cause of
   the Cross-Phase Attacks described in [FETT].  An extension
   specification could be created providing this linkage as a means to
   address the risks.

10.4.  Risks Associated with request_uri

   The introduction of "request_uri" introduces several attack
   possibilities.  Consult the security considerations in Section 7 of
   RFC3986 [RFC3986] for more information regarding risks associated
   with URIs.





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10.4.1.  DDoS Attack on the Authorization Server

   A set of malicious client can launch a DoS attack to the
   authorization server by pointing the "request_uri" to a URI that
   returns extremely large content or extremely slow to respond.  Under
   such an attack, the server may use up its resource and start failing.

   Similarly, a malicious client can specify the "request_uri" value
   that itself points to an authorization request URI that uses
   "request_uri" to cause the recursive lookup.

   To prevent such attack to succeed, the server should (a) check that
   the value of "request_uri" parameter does not point to an unexpected
   location, (b) check the content type of the response is "application/
   oauth-authz-req+jwt", (c) implement a time-out for obtaining the
   content of "request_uri", and (d) not perform recursive GET on the
   "request_uri".

10.4.2.  Request URI Rewrite

   The value of "request_uri" is not signed thus it can be tampered by
   Man-in-the-browser attacker.  Several attack possibilities rise
   because of this, e.g., (a) attacker may create another file that the
   rewritten URI points to making it possible to request extra scope (b)
   attacker launches a DoS attack to a victim site by setting the value
   of "request_uri" to be that of the victim.

   To prevent such attack to succeed, the server should (a) check that
   the value of "request_uri" parameter does not point to an unexpected
   location, (b) check the content type of the response is "application/
   oauth-authz-req+jwt", and (c) implement a time-out for obtaining the
   content of "request_uri".

10.5.  Downgrade Attack

   Unless the protocol used by client and the server is locked down to
   use OAuth JAR, it is possible for an attacker to use RFC6749 requests
   to bypass all the protection provided by this specification.

   To prevent it, this specification defines a new client metadata and
   server metadata "require_signed_request_object" whose value is a
   boolean.

   When the value of it as a client metadata is "true", then the server
   MUST reject the authorization request from the client that does not
   conform to this specification.  It MUST also reject the request if
   the request object uses "alg":"none".  If omitted, the default value
   is "false".



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   When the value of it as a server metadata is "true", then the server
   MUST reject the authorization request from any client that does not
   conform to this specification.  It MUST also reject the request if
   the request object uses "alg":"none".  If omitted, the default value
   is "false".

10.6.  TLS Security Considerations

   Current security considerations can be found in Recommendations for
   Secure Use of TLS and DTLS [BCP195].  This supersedes the TLS version
   recommendations in OAuth 2.0 [RFC6749].

10.7.  Parameter Mismatches

   Given that OAuth parameter values are being sent in two different
   places, as normal OAuth parameters and as Request Object claims,
   implementations must guard against attacks that could use mismatching
   parameter values to obtain unintended outcomes.  That is the reason
   that the two Client ID values MUST match, the reason that only the
   parameter values from the Request Object are to be used, and the
   reason that neither "request" nor "request_uri" can appear in a
   Request Object.

10.8.  Cross-JWT Confusion

   As described in Section 2.8 of [RFC8725], attackers may attempt to
   use a JWT issued for one purpose in a context that it was not
   intended for.  The mitigations described for these attacks can be
   applied to Request Objects.

   One way that an attacker might attempt to repurpose a Request Object
   is to try to use it as a client authentication JWT, as described in
   Section 2.2 of [RFC7523].  A simple way to prevent this is to never
   use the Client ID as the "sub" value in a Request Object.

   Another way to prevent cross-JWT confusion is to use explicit typing,
   as described in Section 3.11 of [RFC8725].  One would explicitly type
   a Request Object by including a "typ" Header Parameter with the value
   "oauth-authz-req+jwt" (which is registered in Section 9.4.1.  Note
   however, that requiring explicitly typed Requests Objects at existing
   authorization servers will break most existing deployments, as
   existing clients are already commonly using untyped Request Objects,
   especially with OpenID Connect [OpenID.Core].  However, requiring
   explicit typing would be a good idea for new OAuth deployment
   profiles where compatibility with existing deployments is not a
   consideration.





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11.  Privacy Considerations

   When the Client is being granted access to a protected resource
   containing personal data, both the Client and the Authorization
   Server need to adhere to Privacy Principles.  RFC 6973 Privacy
   Considerations for Internet Protocols [RFC6973] gives excellent
   guidance on the enhancement of protocol design and implementation.
   The provision listed in it should be followed.

   Most of the provision would apply to The OAuth 2.0 Authorization
   Framework [RFC6749] and The OAuth 2.0 Authorization Framework: Bearer
   Token Usage [RFC6750] and are not specific to this specification.  In
   what follows, only the specific provisions to this specification are
   noted.

11.1.  Collection limitation

   When the Client is being granted access to a protected resource
   containing personal data, the Client SHOULD limit the collection of
   personal data to that which is within the bounds of applicable law
   and strictly necessary for the specified purpose(s).

   It is often hard for the user to find out if the personal data asked
   for is strictly necessary.  A Trust Framework Provider can help the
   user by examining the Client request and comparing to the proposed
   processing by the Client and certifying the request.  After the
   certification, the Client, when making an Authorization Request, can
   submit Authorization Request to the Trust Framework Provider to
   obtain the Request Object URI.  This process is two steps:

   (1)  (Certification Process) The TFP examines the business process of
        the client and determines what claims they need: This is the
        certification process.  Once the client is certified, then they
        are issued a client credential to authenticate against to push
        request objects to the TFP to get the "request_uri".

   (2)  (Translation Process) The client uses the client credential that
        it got to push the request object to the TFP to get the
        "request_uri".  The TFP also verifies that the Request Object is
        consistent with the claims that the client is eligible for, per
        prior step.

   Upon receiving such Request Object URI in the Authorization Request,
   the Authorization Server first verifies that the authority portion of
   the Request Object URI is a legitimate one for the Trust Framework
   Provider.  Then, the Authorization Server issues HTTP GET request to
   the Request Object URI.  Upon connecting, the Authorization Server
   MUST verify the server identity represented in the TLS certificate is



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   legitimate for the Request Object URI.  Then, the Authorization
   Server can obtain the Request Object, which includes the "client_id"
   representing the Client.

   The Consent screen MUST indicate the Client and SHOULD indicate that
   the request has been vetted by the Trust Framework Operator for the
   adherence to the Collection Limitation principle.

11.2.  Disclosure Limitation

11.2.1.  Request Disclosure

   This specification allows extension parameters.  These may include
   potentially sensitive information.  Since URI query parameter may
   leak through various means but most notably through referrer and
   browser history, if the authorization request contains a potentially
   sensitive parameter, the Client SHOULD JWE [RFC7516] encrypt the
   request object.

   Where Request Object URI method is being used, if the request object
   contains personally identifiable or sensitive information, the
   "request_uri" SHOULD be used only once, have a short validity period,
   and MUST have large enough entropy deemed necessary with applicable
   security policy unless the Request Object itself is JWE [RFC7516]
   Encrypted.  The adequate shortness of the validity and the entropy of
   the Request Object URI depends on the risk calculation based on the
   value of the resource being protected.  A general guidance for the
   validity time would be less than a minute and the Request Object URI
   is to include a cryptographic random value of 128bit or more at the
   time of the writing of this specification.

11.2.2.  Tracking using Request Object URI

   Even if the protected resource does not include a personally
   identifiable information, it is sometimes possible to identify the
   user through the Request Object URI if persistent static per-user
   Request Object URIs are used.  A third party may observe it through
   browser history etc. and start correlating the user's activity using
   it.  In a way, it is a data disclosure as well and should be avoided.

   Therefore, per-user persistent Request Object URIs should be avoided.
   Single-use Request Object URIs are one alternative.

12.  Acknowledgements

   The following people contributed to the creation of this document in
   the OAuth working group and other IETF roles.  (Affiliations at the
   time of the contribution are used.)



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   Annabelle Backman (Amazon), Sergey Beryozkin, Ben Campbell (as AD),
   Brian Campbell (Ping Identity), Roman Danyliw (as AD), Vladimir
   Dzhuvinov (Connect2id), Joel Halpern (as GENART), Benjamin Kaduk (as
   AD), Stephen Kent (as SECDIR), Murray Kucherawy (as AD), Warren
   Kumari (as OPSDIR), Torsten Lodderstedt (yes.com), Jim Manico, Axel
   Nennker (Deutsche Telecom), Hannes Tschofenig (ARM), Dirk Balfanz
   (Google), James H.  Manger (Telstra), Kathleen Moriarty (as AD), John
   Panzer (Google), David Recordon (Facebook), Marius Scurtescu
   (Google), Luke Shepard (Facebook), Filip Skokan (Auth0), Eric Vyncke
   (as AD), and Robert Wilton (as AD).

   The following people contributed to creating this document through
   the OpenID Connect Core 1.0 [OpenID.Core].

   Brian Campbell (Ping Identity), George Fletcher (AOL), Ryo Itou
   (Mixi), Edmund Jay (Illumila), Breno de Medeiros (Google), Hideki
   Nara (TACT), Justin Richer (MITRE).

13.  Revision History

   Note to the RFC Editor: Please remove this section from the final
   RFC.

   -30

   o  Changed the MIME Type from "oauth.authz.req+jwt" to "oauth-authz-
      req+jwt", per advice from the designated experts.

   -29

   o  Uniformly use the Change Controller "IETF".

   -28

   o  Removed unused references, as suggested by Roman Danyliw.

   -27

   o  Edits by Mike Jones to address IESG and working group review
      comments, including:

   o  Added Security Considerations text saying not to use the Client ID
      as the "sub" value to prevent Cross-JWT Confusion.

   o  Added Security Considerations text about using explicit typing to
      prevent Cross-JWT Confusion.

   o  Addressed Eric Vyncke's review comments.



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   o  Addressed Robert Wilton's review comments.

   o  Addressed Murray Kucherawy's review comments.

   o  Addressed Benjamin Kaduk's review comments.

   o  Applied spelling and grammar corrections.

   -20

   o  BK comments

   o  Section 3 Removed WAP

   o  Section 4.  Clarified authorization request object parameters,
      removed extension parameters from examples

   o  Section 4.  Specifies application/oauth.authz.req+jwt as mime-type
      fore request objects

   o  Section 5.2.1 Added reference to Capability URLs

   o  Section 5.2.3.  Added entropy fragment to example request

   o  Section 8.  Replaced "subjectAltName dnsName" with "DNS-ID"

   o  Section 9.  Registers authorization request parameters in JWT
      Claims Registry.

   o  Section 9.  Registers application/oauth.authz.req in IANA mime-
      types registry

   o  Section 10.1.  Clarified encrypted request objects are "signed
      then encrypted" to maintain consistency

   o  Section 10.2.  Clarifies trust between AS and TFP

   o  Section 10.3.  Clarified endpoints subject to the practice

   o  Section 10.4 Replaced "redirect_uri" to "request_uri"

   o  Section 10.4.  Added reference to RFC 3986 for risks

   o  Section 10.4.1.d Deleted "do" to maintain grammar flow

   o  Section 10.4.1, 10.4.2 Replaced "application/jose" to
      "application/jwt"




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   o  Section 12.1.  Extended description for submitting authorization
      request to TFP to obtain request object

   o  Section 12.2.2.  Replaced per-user Request Object URI with static
      per-user Request URIs

   o  Section 13.  Combined OAuth WG contributors together

   o  Section Whole doc Replaced application/jwt with application/
      oauth.authz.req+jwt

   -19

   o  AD comments

   o  Section 5.2.1.  s/Requiest URI/Request URI/

   o  Section 8 s/[BCP195] ./[BCP195]./

   o  Section 10.3.  s/sited/cited/

   o  Section 11.  Typo.  s/Curent/Current/

   -17

   o  #78 Typos in content-type

   -16

   o  Treated remaining Ben Campbell comments.

   -15

   o  Removed further duplication

   -14

   o  #71 Reiterate dynamic params are included.

   o  #70 Made clear that AS must return error.

   o  #69 Inconsistency of the need to sign.

   o  Fixed Mimetype.

   o  #67 Inconsistence in requiring HTTPS in request URI.

   o  #66 Dropped ISO 29100 reference.



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   o  #25 Removed Encrypt only option.

   o  #59 Same with #25.

   -13

   o  add TLS Security Consideration section

   o  replace RFC7525 reference with BCP195

   o  moved front tag in FETT reference to fix XML structure

   o  changes reference from SoK to FETT

   -12

   o  fixes #62 - Alexey Melnikov Discuss

   o  fixes #48 - OPSDIR Review : General - delete semicolons after list
      items

   o  fixes #58 - DP Comments for the Last Call

   o  fixes #57 - GENART - Remove "non-normative ... " from examples.

   o  fixes #45 - OPSDIR Review : Introduction - are attacks discovered
      or already opened

   o  fixes #49 - OPSDIR Review : Introduction - Inconsistent colons
      after initial sentence of list items.

   o  fixes #53 - OPSDIR Review : 6.2 JWS Signed Request Object -
      Clarify JOSE Header

   o  fixes #42 - OPSDIR Review : Introduction - readability of 'and' is
      confusing

   o  fixes #50 - OPSDIR Review : Section 4 Request Object - Clarify
      'signed, encrypted, or signed and encrypted'

   o  fixes #39 - OPSDIR Review : Abstract - Explain/Clarify JWS and JWE

   o  fixed #50 - OPSDIR Review : Section 4 Request Object - Clarify
      'signed, encrypted, or signed and encrypted'

   o  fixes #43 - OPSDIR Review : Introduction - 'properties' sounds
      awkward and are not exactly 'properties'




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   o  fixes #56 - OPSDIR Review : 12 Acknowledgements - 'contribution
      is' => 'contribution are'

   o  fixes #55 - OPSDIR Review : 11.2.2 Privacy Considerations - ' It
      is in a way' => 'In a way, it is'

   o  fixes #54 - OPSDIR Review : 11 Privacy Considerations - 'and not
      specific' => 'and are not specific'

   o  fixes #51 - OPSDIR Review : Section 4 Request Object - 'It is
      fine' => 'It is recommended'

   o  fixes #47 - OPSDIR Review : Introduction - 'over- the- wire' =>
      'over-the-wire'

   o  fixes #46 - OPSDIR Review : Introduction - 'It allows' => 'The use
      of application security' for

   o  fixes #44 - OPSDIR Review : Introduction - 'has' => 'have'

   o  fixes #41 - OPSDIR Review : Introduction - missing 'is' before
      'typically sent'

   o  fixes #38 - OPSDIR Review : Section 11 - Delete 'freely
      accessible' regarding ISO 29100

   -11

   o  s/bing/being/

   o  Added history for -10

   -10

   o  #20: KM1 -- some wording that is awkward in the TLS section.

   o  #21: KM2 - the additional attacks against OAuth 2.0 should also
      have a pointer

   o  #22: KM3 -- Nit: in the first line of 10.4:

   o  #23: KM4 -- Mention RFC6973 in Section 11 in addition to ISO 29100

   o  #24: SECDIR review: Section 4 -- Confusing requirements for
      sign+encrypt

   o  #25: SECDIR review: Section 6 -- authentication and integrity need
      not be provided if the requestor encrypts the token?



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   o  #26: SECDIR Review: Section 10 -- why no reference for JWS
      algorithms?

   o  #27: SECDIR Review: Section 10.2 - how to do the agreement between
      client and server "a priori"?

   o  #28: SECDIR Review: Section 10.3 - Indication on "large entropy"
      and "short lifetime" should be indicated

   o  #29: SECDIR Review: Section 10.3 - Typo

   o  #30: SECDIR Review: Section 10.4 - typos and missing articles

   o  #31: SECDIR Review: Section 10.4 - Clearer statement on the lack
      of endpoint identifiers needed

   o  #32: SECDIR Review: Section 11 - ISO29100 needs to be moved to
      normative reference

   o  #33: SECDIR Review: Section 11 - Better English and Entropy
      language needed

   o  #34: Section 4: Typo

   o  #35: More Acknowledgment

   o  #36: DP - More precise qualification on Encryption needed.

   -09

   o  Minor Editorial Nits.

   o  Section 10.4 added.

   o  Explicit reference to Security consideration (10.2) added in
      section 5 and section 5.2.

   o  , (add yourself) removed from the acknowledgment.

   -08

   o  Applied changes proposed by Hannes on 2016-06-29 on IETF OAuth
      list recorded as https://bitbucket.org/Nat/oauth-jwsreq/
      issues/12/.

   o  TLS requirements added.

   o  Security Consideration reinforced.



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   o  Privacy Consideration added.

   o  Introduction improved.

   -07

   o  Changed the abbrev to OAuth JAR from oauth-jar.

   o  Clarified sig and enc methods.

   o  Better English.

   o  Removed claims from one of the example.

   o  Re-worded the URI construction.

   o  Changed the example to use request instead of request_uri.

   o  Clarified that Request Object parameters take precedence
      regardless of request or request_uri parameters were used.

   o  Generalized the language in 4.2.1 to convey the intent more
      clearly.

   o  Changed "Server" to "Authorization Server" as a clarification.

   o  Stopped talking about request_object_signing_alg.

   o  IANA considerations now reflect the current status.

   o  Added Brian Campbell to the contributors list.  Made the lists
      alphabetic order based on the last names.  Clarified that the
      affiliation is at the time of the contribution.

   o  Added "older versions of " to the reference to IE URI length
      limitations.

   o  Stopped talking about signed or unsigned JWS etc.

   o  1.Introduction improved.

   -06

   o  Added explanation on the 512 chars URL restriction.

   o  Updated Acknowledgements.

   -05



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   o  More alignment with OpenID Connect.

   -04

   o  Fixed typos in examples. (request_url -> request_uri, cliend_id ->
      client_id)

   o  Aligned the error messages with the OAuth IANA registry.

   o  Added another rationale for having request object.

   -03

   o  Fixed the non-normative description about the advantage of static
      signature.

   o  Changed the requirement for the parameter values in the request
      itself and the request object from 'MUST MATCH" to 'Req Obj takes
      precedence.

   -02

   o  Now that they are RFCs, replaced JWS, JWE, etc. with RFC numbers.

   -01

   o  Copy Edits.

14.  References

14.1.  Normative References

   [BCP195]   Sheffer, Y., Holz, R., and P. Saint-Andre,
              "Recommendations for Secure Use of Transport Layer
              Security (TLS) and Datagram Transport Layer Security
              (DTLS)", BCP 195, RFC 7525, May 2015.

   [IANA.MediaTypes]
              IANA, "Media Types",
              <http://www.iana.org/assignments/media-types>.

   [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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   [RFC3629]  Yergeau, F., "UTF-8, a transformation format of ISO
              10646", STD 63, RFC 3629, DOI 10.17487/RFC3629, November
              2003, <https://www.rfc-editor.org/info/rfc3629>.

   [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>.

   [RFC6125]  Saint-Andre, P. and J. Hodges, "Representation and
              Verification of Domain-Based Application Service Identity
              within Internet Public Key Infrastructure Using X.509
              (PKIX) Certificates in the Context of Transport Layer
              Security (TLS)", RFC 6125, DOI 10.17487/RFC6125, March
              2011, <https://www.rfc-editor.org/info/rfc6125>.

   [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>.

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

   [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>.

   [RFC7515]  Jones, M., Bradley, J., and N. Sakimura, "JSON Web
              Signature (JWS)", RFC 7515, DOI 10.17487/RFC7515, May
              2015, <https://www.rfc-editor.org/info/rfc7515>.

   [RFC7516]  Jones, M. and J. Hildebrand, "JSON Web Encryption (JWE)",
              RFC 7516, DOI 10.17487/RFC7516, May 2015,
              <https://www.rfc-editor.org/info/rfc7516>.

   [RFC7518]  Jones, M., "JSON Web Algorithms (JWA)", RFC 7518,
              DOI 10.17487/RFC7518, May 2015,
              <https://www.rfc-editor.org/info/rfc7518>.






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   [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>.

   [RFC8141]  Saint-Andre, P. and J. Klensin, "Uniform Resource Names
              (URNs)", RFC 8141, DOI 10.17487/RFC8141, April 2017,
              <https://www.rfc-editor.org/info/rfc8141>.

   [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>.

   [RFC8259]  Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
              Interchange Format", STD 90, RFC 8259,
              DOI 10.17487/RFC8259, December 2017,
              <https://www.rfc-editor.org/info/rfc8259>.

   [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>.

14.2.  Informative References

   [BASIN]    Basin, D., Cremers, C., and S. Meier, "Provably Repairing
              the ISO/IEC 9798 Standard for Entity Authentication",
              Journal of Computer Security - Security and Trust
              Principles Volume 21 Issue 6, Pages 817-846, November
              2013,
              <https://www.cs.ox.ac.uk/people/cas.cremers/downloads/
              papers/BCM2012-iso9798.pdf>.

   [CapURLs]  Tennison, J., "Good Practices for Capability URLs",
              W3C Working Draft, February 2014,
              <https://www.w3.org/TR/capability-urls/>.

   [FETT]     Fett, D., Kusters, R., and G. Schmitz, "A Comprehensive
              Formal Security Analysis of OAuth 2.0", CCS '16
              Proceedings of the 2016 ACM SIGSAC Conference on Computer
              and Communications Security Pages 1204-1215 , October
              2016, <https://arxiv.org/pdf/1601.01229v2.pdf>.

   [IANA.JWT.Claims]
              IANA, "JSON Web Token Claims",
              <http://www.iana.org/assignments/jwt>.






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   [IANA.OAuth.Parameters]
              IANA, "OAuth Parameters",
              <http://www.iana.org/assignments/oauth-parameters>.

   [OpenID.Core]
              Sakimura, N., Bradley, J., Jones, M., de Medeiros, B., and
              C. Mortimore, "OpenID Connect Core 1.0", OpenID
              Foundation Standards, February 2014,
              <http://openid.net/specs/openid-connect-core-1_0.html>.

   [RFC2046]  Freed, N. and N. Borenstein, "Multipurpose Internet Mail
              Extensions (MIME) Part Two: Media Types", RFC 2046,
              DOI 10.17487/RFC2046, November 1996,
              <https://www.rfc-editor.org/info/rfc2046>.

   [RFC6819]  Lodderstedt, T., Ed., McGloin, M., and P. Hunt, "OAuth 2.0
              Threat Model and Security Considerations", RFC 6819,
              DOI 10.17487/RFC6819, January 2013,
              <https://www.rfc-editor.org/info/rfc6819>.

   [RFC6838]  Freed, N., Klensin, J., and T. Hansen, "Media Type
              Specifications and Registration Procedures", BCP 13,
              RFC 6838, DOI 10.17487/RFC6838, January 2013,
              <https://www.rfc-editor.org/info/rfc6838>.

   [RFC6973]  Cooper, A., Tschofenig, H., Aboba, B., Peterson, J.,
              Morris, J., Hansen, M., and R. Smith, "Privacy
              Considerations for Internet Protocols", RFC 6973,
              DOI 10.17487/RFC6973, July 2013,
              <https://www.rfc-editor.org/info/rfc6973>.

   [RFC7523]  Jones, M., Campbell, B., and C. Mortimore, "JSON Web Token
              (JWT) Profile for OAuth 2.0 Client Authentication and
              Authorization Grants", RFC 7523, DOI 10.17487/RFC7523, May
              2015, <https://www.rfc-editor.org/info/rfc7523>.

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

   [RFC8725]  Sheffer, Y., Hardt, D., and M. Jones, "JSON Web Token Best
              Current Practices", BCP 225, RFC 8725,
              DOI 10.17487/RFC8725, February 2020,
              <https://www.rfc-editor.org/info/rfc8725>.






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Authors' Addresses

   Nat Sakimura
   NAT.Consulting
   2-22-17 Naka
   Kunitachi, Tokyo  186-0004
   Japan

   Phone: +81-42-580-7401
   Email: nat@nat.consulting
   URI:   http://nat.sakimura.org/


   John Bradley
   Yubico
   Casilla 177, Sucursal Talagante
   Talagante, RM
   Chile

   Phone: +1.202.630.5272
   Email: ve7jtb@ve7jtb.com
   URI:   http://www.thread-safe.com/


   Michael B. Jones
   Microsoft
   One Microsoft Way
   Redmond, Washington  98052
   United States of America

   Email: mbj@microsoft.com
   URI:   https://self-issued.info/



















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