Internet DRAFT - draft-selander-cose-kid-int
draft-selander-cose-kid-int
Network Working Group G. Selander
Internet-Draft J. Preuß Mattsson
Intended status: Standards Track Ericsson
Expires: 20 September 2022 19 March 2022
Integer value for the CBOR Object Signing and Encryption (COSE) key
identifier
draft-selander-cose-kid-int-01
Abstract
This document extends the CBOR Object Signing and Encryption (COSE)
parameter kid to CBOR integer values.
Status of This Memo
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This Internet-Draft will expire on 20 September 2022.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Security Considerations . . . . . . . . . . . . . . . . . . . 3
3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 3
3.1. COSE Header Parameters Registry . . . . . . . . . . . . . 3
3.2. COSE Key Common Parameters Registry . . . . . . . . . . . 3
3.3. CWT Confirmation Methods . . . . . . . . . . . . . . . . 3
4. References . . . . . . . . . . . . . . . . . . . . . . . . . 4
4.1. Normative References . . . . . . . . . . . . . . . . . . 4
4.2. Informative References . . . . . . . . . . . . . . . . . 4
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5
1. Introduction
Many Internet of Things (IoT) deployments require technologies which
are highly performant in constrained environments [RFC7228]. The
connectivity for these settings may exhibit extremely restricted
bandwidth constraints, for which byte level optimizations are
motivated, see [I-D.ietf-lake-reqs].
The use of CBOR [RFC8949] enables a compact encoding of protected
data as COSE objects [I-D.ietf-cose-rfc8152bis-struct], which is a
basic building block in various IoT security settings such as CWT
[RFC8392], OSCORE [RFC8613], and ACE-OAuth
[I-D.ietf-ace-oauth-authz]. COSE defines the key identifier
parameter kid used to identify keys used in the COSE object.
The value of the kid parameter is specified to be encoded as a CBOR
byte string, which (with the exception of the empty string) requires
at least two bytes on the wire. For comparison, CBOR encoding of
small integers (-24, ..., 23) need only one byte on the wire. Since
many IoT deployments may use local identifiers for which a few unique
identifiers are sufficient, the use of CBOR integers as key
identifiers would reduce the overhead due to transport of COSE
objects.
This specification amends this limitation by extending the COSE
parameter kid to allow CBOR integer values. kid is used in different
instances, which all need to be extended to CBOR int encoding:
* The kid COSE header parameter, see Section 3.1.
* The kid COSE Key Common Parameter, see Section 3.2.
* The kid CWT Confirmation Method, see Section 3.3.
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2. Security Considerations
There are no additional security considerations compared to key
identifiers to being byte strings.
3. IANA Considerations
3.1. COSE Header Parameters Registry
IANA has extended the Value Type of kid in the "COSE Header
Parameters" registry under the group name "CBOR Object Signing and
Encryption (COSE)" to also allow the Value Type int. The resulting
Value Type is bstr / int. The Value Registry for this item is empty
and omitted from the table below.
+------+-------+------------+----------------+
| Name | Label | Value Type | Description |
+------+-------+------------+----------------+
| kid | 4 | bstr / int | Key identifier |
+------+-------+------------+----------------+
3.2. COSE Key Common Parameters Registry
IANA has extended the Value Type of kid in the "COSE Key Common
Parameters" registry under the group name "CBOR Object Signing and
Encryption (COSE)" to also allow the Value Type int. The resulting
Value Type is bstr / int. The Value Registry for this item is empty
and omitted from the table below.
+------+-------+------------+---------------------------+
| Name | Label | Value Type | Description |
+------+-------+------------+---------------------------+
| kid | 2 | bstr / int | Key identification value |
| | | | - match to kid in message |
+------+-------+------------+---------------------------+
3.3. CWT Confirmation Methods
IANA has extended the Value Type of kid in the "CWT Confirmation
Methods" registry under the group name "CBOR Web Token (CWT) Claims"
to also allow the Value Type int. The resulting Value Type is bstr /
int. The Value Registry for this item is empty and omitted from the
table below.
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+------+-------+------------+---------------------------+
| Name | Label | Value Type | Description |
+------+-------+------------+---------------------------+
| kid | 3 | bstr / int | Key identification value |
| | | | - match to kid in message |
+------+-------+------------+---------------------------+
4. References
4.1. Normative References
[I-D.ietf-cose-rfc8152bis-struct]
Schaad, J., "CBOR Object Signing and Encryption (COSE):
Structures and Process", Work in Progress, Internet-Draft,
draft-ietf-cose-rfc8152bis-struct-15, 1 February 2021,
<https://www.ietf.org/archive/id/draft-ietf-cose-
rfc8152bis-struct-15.txt>.
[RFC8949] Bormann, C. and P. Hoffman, "Concise Binary Object
Representation (CBOR)", STD 94, RFC 8949,
DOI 10.17487/RFC8949, December 2020,
<https://www.rfc-editor.org/info/rfc8949>.
4.2. Informative References
[I-D.ietf-ace-oauth-authz]
Seitz, L., Selander, G., Wahlstroem, E., Erdtman, S., and
H. Tschofenig, "Authentication and Authorization for
Constrained Environments (ACE) using the OAuth 2.0
Framework (ACE-OAuth)", Work in Progress, Internet-Draft,
draft-ietf-ace-oauth-authz-46, 8 November 2021,
<https://www.ietf.org/archive/id/draft-ietf-ace-oauth-
authz-46.txt>.
[I-D.ietf-lake-reqs]
Vucinic, M., Selander, G., Mattsson, J. P., and D. Garcia-
Carrillo, "Requirements for a Lightweight AKE for OSCORE",
Work in Progress, Internet-Draft, draft-ietf-lake-reqs-04,
8 June 2020, <https://www.ietf.org/archive/id/draft-ietf-
lake-reqs-04.txt>.
[RFC7228] Bormann, C., Ersue, M., and A. Keranen, "Terminology for
Constrained-Node Networks", RFC 7228,
DOI 10.17487/RFC7228, May 2014,
<https://www.rfc-editor.org/info/rfc7228>.
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[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>.
[RFC8613] Selander, G., Mattsson, J., Palombini, F., and L. Seitz,
"Object Security for Constrained RESTful Environments
(OSCORE)", RFC 8613, DOI 10.17487/RFC8613, July 2019,
<https://www.rfc-editor.org/info/rfc8613>.
Acknowledgments
Authors' Addresses
Göran Selander
Ericsson AB
SE-164 80 Stockholm
Sweden
Email: goran.selander@ericsson.com
John Preuß Mattsson
Ericsson AB
SE-164 80 Stockholm
Sweden
Email: john.mattsson@ericsson.com
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