A CBOR Tag for Unprotected CWT Claims Sets
draft-birkholz-rats-uccs-01

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RATS Working Group                                           H. Birkholz
Internet-Draft                                            Fraunhofer SIT
Intended status: Standards Track                         J. "O'Donoghue"
Expires: December 3, 2020                     Qualcomm Technologies Inc.
                                                           N. Cam-Winget
                                                           Cisco Systems
                                                              C. Bormann
                                                 Universitaet Bremen TZI
                                                           June 01, 2020

               A CBOR Tag for Unprotected CWT Claims Sets
                      draft-birkholz-rats-uccs-01

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 December 3, 2020.

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
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   (https://trustee.ietf.org/license-info) in effect on the date of
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   carefully, as they describe your rights and restrictions with respect

Birkholz, et al.        Expires December 3, 2020                [Page 1]
Internet-Draft         Unprotected CWT Claims Sets             June 2020

   to this document.  Code Components extracted from this document must
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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Motivation and Requirements . . . . . . . . . . . . . . . . .   3
   3.  Characteristics of a Secure Channel . . . . . . . . . . . . .   3
     3.1.  UCCS and Remote ATtestation procedureS (RATS) . . . . . .   4
     3.2.  Privacy Preserving Channels . . . . . . . . . . . . . . .   5
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   6
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .   6
     6.2.  Informative References  . . . . . . . . . . . . . . . . .   7
   Appendix A.  Example  . . . . . . . . . . . . . . . . . . . . . .   7
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   7

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 provided through the transfer
   protocol and thus omitted from the information in a CWT without
   compromising the intended goal of authenticity and integrity.  If a
   mutually Secured Channel is established 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.  Similarly, if there is one-way
   authentication, the party that did not authenticate may be in a
   position to send authentication information through this channel that
   allows the already authenticated party to authenticate the other
   party.

   This specification allocates a CBOR tag to mark Unprotected CWT
   Claims Sets (UCCS) as such and discusses conditions for its proper
   use in the scope of Remote ATtestation procedureS (RATS).

   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