Internet DRAFT - draft-looker-cose-cwt-claims-in-headers
draft-looker-cose-cwt-claims-in-headers
COSE T. Looker
Internet-Draft Mattr
Intended status: Standards Track M. Jones
Expires: 2 September 2022 Microsoft
1 March 2022
CBOR Web Token (CWT) Claims in COSE Headers
draft-looker-cose-cwt-claims-in-headers-00
Abstract
This document describes how to include CBOR Web Token (CWT) claims in
the header parameters of any COSE structure. This functionality
helps to facilitate applications that wish to make use of CBOR Web
Token (CWT) claims in encrypted COSE structures and/or COSE
structures featuring detached signatures, while having some of those
claims be available before decryption and/or without inspecting the
detached payload.
Discussion Venues
This note is to be removed before publishing as an RFC.
Source for this draft and an issue tracker can be found at
https://github.com/tplooker/draft-looker-cose-cwt-claims-in-headers.
Status of This Memo
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This Internet-Draft will expire on 2 September 2022.
Copyright Notice
Copyright (c) 2022 IETF Trust and the persons identified as the
document authors. All rights reserved.
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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
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provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Representation . . . . . . . . . . . . . . . . . . . . . . . 3
4. Privacy Considerations . . . . . . . . . . . . . . . . . . . 3
5. Security Considerations . . . . . . . . . . . . . . . . . . . 3
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 3
7. Normative References . . . . . . . . . . . . . . . . . . . . 3
8. Informative References . . . . . . . . . . . . . . . . . . . 3
Appendix A. Document History . . . . . . . . . . . . . . . . . . 4
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 4
1. Introduction
In some applications of COSE, it is useful to have a standard
representation of CWT claims [RFC8392] available in the header
parameters. These include encrypted COSE structures, which may or
may not be an encrypted CWT and/or those featuring a detached
signature.
Section 5.3 of the JWT RFC [RFC7519] defined a similar mechanism for
expressing selected JWT based claims as JOSE header parameters. This
JWT feature was motivated by the desire to have certain claims, such
as Key ID values, be visible to software processing the JWT, even
though the JWT is encrypted. No corresponding feature was
standardized for CWTs, which was an omission that this specification
corrects.
Directly including CWT claim values as COSE header parameter values
would not work, since there are conflicts between the numeric header
parameter assignments and the numeric CWT claim assignments.
Instead, this specification defines a single header parameter
registered in the IANA "COSE Header Parameters" registry that creates
a location to store CWT claims in a COSE header parameter.
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2. Terminology
3. Representation
This document defines the following COSE header parameter:
+========+================+=======+============+===============+
| Name | Label | Value | Value | Description |
| | | Type | Registry | |
+========+================+=======+============+===============+
| cwt | TBD (requested | map | [IANA.CWT] | location for |
| claims | assignment 11) | | | CWT claims in |
| | | | | COSE headers |
+--------+----------------+-------+------------+---------------+
Table 1
4. Privacy Considerations
Some of the registered CWT claims may contain privacy-sensitive
information. Therefore care must be taken when expressing CWT claims
in COSE headers.
5. Security Considerations
In cases where CWT claims are both present in the payload and the
header, an application receiving such as structure MUST verify that
their values are identical, unless the application defines other
specific processing rules for these claims.
6. IANA Considerations
IANA is requested to register the new COSE Header parameter in the
table in Section 3 in the "COSE Header Parameters" registry
[IANA.COSE].
7. Normative References
[IANA.COSE]
IANA, "COSE Header Parameters",
<https://www.iana.org/assignments/cose/cose.xhtml#header-
parameters>.
[IANA.CWT] IANA, "CBOR Web Token (CWT) Claims",
<https://www.iana.org/assignments/cwt/cwt.xhtml>.
8. Informative References
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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>.
[RFC8392] Jones, M., Wahlstroem, E., Erdtman, S., and H. Tschofenig,
"CBOR Web Token (CWT)", RFC 8392, DOI 10.17487/RFC8392,
May 2018, <https://www.rfc-editor.org/info/rfc8392>.
Appendix A. Document History
-00
* Initial version
Authors' Addresses
Tobias Looker
Mattr
Email: tobias.looker@mattr.global
Michael B. Jones
Microsoft
Email: mbj@microsoft.com
URI: https://self-issued.info/
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