WG Review: CBOR Object Signing and Encryption (cose)

[The IESG <[e-mail]>]

A new IETF WG has been proposed in the Security Area. 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 ([e-mail]) by 2018-10-25.

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

Chairs:
  Justin Richer <[e-mail]>
  Kepeng Li <[e-mail]>

Assigned Area Director:
  Eric Rescorla <[e-mail]>

Security Area Directors:
  Eric Rescorla <[e-mail]>
  Benjamin Kaduk <[e-mail]>

Mailing list:
  Address: [e-mail]
  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, ANAMA, 6TiSCH and SUIT) as well as
outside of the IETF (i.e. W3C and FIDO).  There are a number of
implementations, both open source and private, now in existence.  The
specification is now sufficiently mature that it makes sense to try
and advance it to STD status.

The standards progression work will focus on:
1. Should the document be split in two?  One document for the
structures and one document for the algorithm definitions.
2.  What areas in the document need clarification before the document
can be progressed?
3.  What implementations exist and do they cover all of the major
sections of the document?

There are a small number of COSE related documents that will also be
addressed by the working group dealing with additional attributes and
algorithms that need to be reviewed and published.  The first set of
three are listed in the deliverables.  A re-charter will be required
to expand this list.

The SUIT working group has identified a need for the use of hash-based
signatures in the form of Leighton-Micali Signatures (LMS)
(draft-mcgrew-hash-sigs).  This signature form is resistant to quantum
computing and is low-cost for validation.  The SUIT working group
additionally has identified a need for registering hash functions for
indirect packaging.

The W3C Web Authentication working group has identified a need for the
ability to use algorithms which are currently part of TPMs which are
widely deployed.

At the time COSE was developed, there was a sense that X.509
certificates was not a feature that needed to be transferred from the
JOSE key document (RFC 7517).  Since that time a better sense of how
certificates would be used both in the IoT sphere and with COSE
outside of the IoT sphere has been developed.  The need to be able to
identify X.509 certificates is now a feature that needs to be
provided.  This will additionally require definition of a small number
of hash functions for compact references to certificates.

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 or active IETF WG documents.

The working group will coordinate its progress with the ACE, SUIT and
CORE working groups to ensure that we are 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 will have five deliverables:

1. Republishing a version of RFC 8152 suitable for advancement to full
standard.
2. Use of Hash-based Signature algorithms in COSE using
draft-housley-suit-cose-hash-sig as a starting point.
3. Placement of X.509 certificates in COSE messages and keys using
draft-schaad-cose-x509 as a starting point.
4. Define the algorithms needed for W3C Web Authentication for COSE using
draft-jones-webauthn-cose-algorithms and draft-jones-webauthn-secp256k1 as a
starting point.
5. Define a small set of hash functions.

Milestones:

TBD