Encoding claims in the OAuth 2 state parameter using a JWT
draft-bradley-oauth-jwt-encoded-state-08

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Network Working Group                                    J. Bradley, Ed.
Internet-Draft                                                      Ping
Intended status: Experimental                             T. Lodderstedt
Expires: July 9, 2018
                                                             H. Zandbelt
                                                                    Ping
                                                        January 05, 2018

       Encoding claims in the OAuth 2 state parameter using a JWT
                draft-bradley-oauth-jwt-encoded-state-08

Abstract

   This draft provides a method for a client to encode one or more
   elements encoding information about the session into the OAuth 2
   "state" parameter.

Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].

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
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   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 July 9, 2018.

Copyright Notice

   Copyright (c) 2018 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

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   (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
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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  The state JSON Web Token claims . . . . . . . . . . . . . . .   3
   3.  Validating the state parameter  . . . . . . . . . . . . . . .   5
   4.  Creating a Request Forgery Protection (rfp) claim value.  . .   5
     4.1.  Stateful Clients. . . . . . . . . . . . . . . . . . . . .   6
     4.2.  Stateless Clients.  . . . . . . . . . . . . . . . . . . .   6
     4.3.  Responses Initiated by the Issuer . . . . . . . . . . . .   6
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
     6.1.  State Redirection . . . . . . . . . . . . . . . . . . . .   7
     6.2.  State Modification  . . . . . . . . . . . . . . . . . . .   7
     6.3.  State Confidentiality . . . . . . . . . . . . . . . . . .   7
     6.4.  Passing paramaters to the AS  . . . . . . . . . . . . . .   7
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   7
   8.  Normative References  . . . . . . . . . . . . . . . . . . . .   7
   Appendix A.  Document History . . . . . . . . . . . . . . . . . .   8
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   8

1.  Introduction

   In the OAuth 2.0 Authorization protocol [RFC6749] , the Authorization
   server SHOULD perform an exact string comparison of the
   "redirect_uri" parameter with the "redirect_uri" parameter registered
   by by the client.  This is essential for preventing token leakage to
   third parties in the OAuth implicit flow.

   As a result of this clients can not safely add extra query parameters
   to the "redirect_uri" parameter that encode additional client state
   information.

   The Client MUST use the "state" parameter to encode both Cross Site
   Request Forgery protection and any other state information it wishes
   to preserve for itself regarding the authorization request.

   This draft proposes a mechanism whereby multiple state attributes can
   be encoded into a JSON Web Token JWT [RFC7519] for use as the value
   of the "state" parameter.

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   The JWT may be sent without integrity protection, with integrity
   protection JWS [RFC7515], or with both integrity and confidentiality
   protection JWE [RFC7516].  The client is free to choose the