CBOR Object Signing and Encryption
CBOR Object Signing and Encryption WG
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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
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) 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? The first document would
contain the definitions of the structures and rules for processing
them. The second document would contain the set of original
algorithms that were defined.
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?
4. Resolution of any Errata or ambiguities in 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
are listed below 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
computer attacks and is low-cost for validation. The SUIT working group
additionally has identified a need for registering hash functions for
The W3C Web Authentication working group has identified a need for the
ability to use algorithms which are currently part of TPMs which are
At the time COSE was developed, there was a sense that X.509
certificates were not a feature that needed to be transferred from the
JOSE key document (RFC 7517). Since that time a better sense of how
X.509 certificates would be used both in the IoT sphere and with COSE
outside of the IoT sphere has been developed. The ability to identify
or carry X.509 certificates now needs to be provided. This will require
the definition of a small number of hash functions for compact references
to X.509 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, 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 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 Internet
2. Use of Hash-based Signature algorithms in COSE using
draft-housley-suit-cose-hash-sig as a starting point (Informational).
3. Placement of X.509 certificates in COSE messages and keys using
draft-schaad-cose-x509 as a starting point (Informational).
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 (Informational).
5. Define a small number of hash functions for X.509 certificate thumbprints
and for indirect signing (for SUIT) (Informational).