Subject: [secdir] [new-work] WG Review: CBOR Object Signing and Encryption (cose)

From: The IESG <[email-masked]>
Date: Wed, 31 Mar 2021 09:59:33 -0700

The CBOR Object Signing and Encryption (cose) WG in the Security Area of the
IETF is undergoing rechartering. The IESG has not made any determination yet.
The following draft charter was submitted, and is provided for informational
purposes only. Please send your comments to the IESG mailing list
([email-masked]) by 2021-04-07.

CBOR Object Signing and Encryption (cose)
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Current status: Active WG

Chairs:
  Matthew Miller <[email-masked]>
  Ivaylo Petrov <[email-masked]>
  Mike Jones <[email-masked]>

Assigned Area Director:
  Benjamin Kaduk <[email-masked]>

Security Area Directors:
  Benjamin Kaduk <[email-masked]>
  Roman Danyliw <[email-masked]>

Mailing list:
  Address: [email-masked]
  To subscribe: https://www.ietf.org/mailman/listinfo/cose
  Archive: https://mailarchive.ietf.org/arch/browse/cose/

Group page: https://datatracker.ietf.org/group/cose/

Charter: https://datatracker.ietf.org/doc/charter-ietf-cose/

CBOR Object Signing and Encryption (COSE, RFC 8152) describes how to
create and process signatures, message authentication codes, and
encryption using Concise Binary Object Representation (CBOR, RFC 7049)
for serialization. COSE additionally describes a representation for
cryptographic keys.

COSE has been picked up and is being used both by a number of groups
within the IETF (i.e., ACE, CORE, ANIMA, 6TiSCH and SUIT) and
outside the IETF (i.e., W3C and FIDO). There are a number of
implementations, both open source and private, now in existence.
The specification has advanced to STD status.

The COSE working group will deal with two types of documents going forward:

1.  Documents that describe the use of cryptographic algorithms in COSE.
2.  Documents which describe additional attributes for COSE.

The WG will evaluate, and potentially adopt, documents dealing with algorithms
that would fit the criteria of being IETF consensus algorithms.
Potential candidates would include those algorithms that have been evaluated
by the CFRG and algorithms which have gone through a public review and
evaluation process such as was done for the NIST SHA-3 algorithms. Potential
candidate would not include national-standards-based algorithms that have not
gone through a similar public review process.

The WG will produce documents for new attributes only if they are in the
list of deliverables below.  A re-charter will be required to expand that
list. The WG is expected as part of normal processing to review and comment
on attributes that are not in charter but are of general public interest.

Key management and binding of keys to identities are out of scope for
the working group. The COSE WG will not innovate in terms of
cryptography. The specification of algorithms in COSE is limited to
those in RFCs, active CFRG or IETF WG documents, or algorithms which
have been positively reviewed by the CFRG.

The working group will coordinate its progress with the ACE, SUIT and
CORE working groups to ensure that it is fulfilling the needs of
these constituencies to the extent relevant to their work. Other
groups may be added to this list as the set of use cases is expanded,
in consultation with the responsible Area Director.

The WG currently has two work items:

1. One or more documents describing the proper use of algorithms.
These algorithms must meet the requirements outlined above.

2. A CBOR encoding of the certificate profile defined in RFC 5280.
It is expected that the encoding works with RFC 7925 and takes into
consideration any updates in draft-ietf-uta-tls13-iot-profile-00.  The
encoding may also include other important IoT certificate profiles like IEEE
802.1AR.
The main objective is to define a method of encoding current X.509
certificates that meet a specific profile into a smaller format. This encoding
is invertible, so they can be expanded and normal X.509 certificate processing
can be used.  The data structures used for such encoding of X.509
certificates are expected to produce a compact encoding for certificate
information, and are not necessarily tied specifically to X.509 certificates.
 Accordingly, a secondary objective is to reuse these data structures to
produce a natively signed CBOR certificate encoding; such a structure is
relevant in situations where DER parsing and the machinery to convert between
CBOR and DER encodings are unnecessary overhead, such as embedded
implementations.  The possibility of a joint certificate artifact, conveyed
in CBOR encoding but including signatures over both the CBOR and DER
encodings, may be explored.  CBOR encoding of other X.509 certificate related
data structures may also be specified to support relevant functions such as
revocation: Certificate Revocation List (RFC 5280) or OSCP Request/Response
(RFC 6960); or certificate enrollment: Certificate Signing Request (RFC
2986). draft-mattsson-cose-cbor-cert-compress is expected to be a good
starting point for this work.  The working group will collaborate and
coordinate with other IETF WGs such as TLS, UTA, LAKE to understand and
validate the requirements and solution.

Milestones:

  Jun 2021 - Adopt draft for compressed certificate encoding as a Working
  Group item

  Dec 2021 - Submit draft for compressed certificate encoding to the IESG for
  publication

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