A CBOR Tag for Unprotected CWT Claims Sets
draft-birkholz-rats-uccs-00

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RATS Working Group                                           H. Birkholz
Internet-Draft                                            Fraunhofer SIT
Intended status: Standards Track                           N. Cam-Winget
Expires: September 10, 2020                                Cisco Systems
                                                              C. Bormann
                                                 Universitaet Bremen TZI
                                                          March 09, 2020

               A CBOR Tag for Unprotected CWT Claims Sets
                      draft-birkholz-rats-uccs-00

Abstract

   CBOR Web Token (CWT, RFC 8392) Claims Sets sometimes do not need the
   protection afforded by wrapping them into COSE, as is required for a
   true CWT.  This specification defines a CBOR tag for such unprotected
   CWT claims sets (UCCS) and discusses conditions for its proper use.

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   This Internet-Draft will expire on September 10, 2020.

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   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
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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Characteristics of a Secure Channel . . . . . . . . . . . . .   3
   3.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   3
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   3
   5.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   4
     5.1.  Normative References  . . . . . . . . . . . . . . . . . .   4
     5.2.  Informative References  . . . . . . . . . . . . . . . . .   4
   Appendix A.  Example  . . . . . . . . . . . . . . . . . . . . . .   4
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   5

1.  Introduction

   A CBOR Web Token (CWT) as specified by [RFC8392] is always wrapped in
   a CBOR Object Signing and Encryption (COSE, [RFC8152]) envelope.
   COSE provides - amongst other things - the integrity protection
   mandated by RFC 8392 and optional encryption for CWTs.  Under the
   right circumstances, though, a signature providing proof for
   authenticity and integrity can be omitted from the information in a
   CWT without compromising the intended goal of authenticity and
   integrity.  If a secure channel is established in an appropriate
   fashion between two remote peers, and if that secure channel provides
   the correct properties, it is possible to omit the protection
   provided by COSE, creating a use case for unprotected CWT Claims
   Sets.

   This specification allocates a CBOR tag to mark Unprotected CWT
   Claims Sets (UCCS) as such and discusses conditions for its proper
   use.

   This specification does not change [RFC8392]: A true CWT does not
   make use of the tag allocated here; the UCCS tag is an alternative to
   using COSE protection and a CWT tag.

1.1.  Terminology

   The terms Claim and Claims Set are used as in [RFC8392].

   UCCS:  Unprotected CWT Claims Set

   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

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   BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

2.  Characteristics of a Secure Channel

   A Secure Channel for the conveyance of UCCS needs to provide the
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