Proof-of-Possession Key Semantics for JSON Web Tokens (JWTs)
RFC 7800

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Internet Engineering Task Force (IETF)                          M. Jones
Request for Comments: 7800                                     Microsoft
Category: Standards Track                                     J. Bradley
ISSN: 2070-1721                                            Ping Identity
                                                           H. Tschofenig
                                                             ARM Limited
                                                              April 2016

      Proof-of-Possession Key Semantics for JSON Web Tokens (JWTs)

Abstract

   This specification describes how to declare in a JSON Web Token (JWT)
   that the presenter of the JWT possesses a particular proof-of-
   possession key and how the recipient can cryptographically confirm
   proof of possession of the key by the presenter.  Being able to prove
   possession of a key is also sometimes described as the presenter
   being a holder-of-key.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc7800.

Copyright Notice

   Copyright (c) 2016 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
   (http://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.

Jones, et al.                Standards Track                    [Page 1]
RFC 7800            Proof-of-Possession Key for JWTs          April 2016

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Notational Conventions  . . . . . . . . . . . . . . . . .   5
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   5
   3.  Representations for Proof-of-Possession Keys  . . . . . . . .   5
     3.1.  Confirmation Claim  . . . . . . . . . . . . . . . . . . .   6
     3.2.  Representation of an Asymmetric Proof-of-Possession Key .   7
     3.3.  Representation of an Encrypted Symmetric Proof-of-
           Possession Key  . . . . . . . . . . . . . . . . . . . . .   7
     3.4.  Representation of a Key ID for a Proof-of-Possession Key    8
     3.5.  Representation of a URL for a Proof-of-Possession Key . .   9
     3.6.  Specifics Intentionally Not Specified . . . . . . . . . .  10
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .  10
   5.  Privacy Considerations  . . . . . . . . . . . . . . . . . . .  11
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  11
     6.1.  JSON Web Token Claims Registration  . . . . . . . . . . .  12
       6.1.1.  Registry Contents . . . . . . . . . . . . . . . . . .  12
     6.2.  JWT Confirmation Methods Registry . . . . . . . . . . . .  12
       6.2.1.  Registration Template . . . . . . . . . . . . . . . .  12
       6.2.2.  Initial Registry Contents . . . . . . . . . . . . . .  13
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  13
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .  13
     7.2.  Informative References  . . . . . . . . . . . . . . . . .  14
   Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .  15
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  15

1.  Introduction

   This specification describes how a JSON Web Token [JWT] can declare
   that the presenter of the JWT possesses a particular proof-of-
   possession (PoP) key and how the recipient can cryptographically
   confirm proof of possession of the key by the presenter.  Proof of
   possession of a key is also sometimes described as the presenter
   being a holder-of-key.  The [OAUTH-POP-ARCH] specification describes
   key confirmation, among other confirmation mechanisms.  This
   specification defines how to communicate confirmation key information
   in JWTs.

   Envision the following two use cases.  The first use case employs a
   symmetric proof-of-possession key and the second use case employs an
   asymmetric proof-of-possession key.

Jones, et al.                Standards Track                    [Page 2]