Russ, I looked into KMAC and it seems like it can also be included as a set of fully specified algorithms parameterized like you mentioned. Other proposed uses in IPsec [3] do make use of different customization strings, which might apply in this situation but I’ll leave that detail to other experts.
I have an initial draft going through internal release review. After that I can add you as coauthor if you’d like and can point me to (e.g. a recent draft that has) your contact info. Thanks in advance, Brian S. [3] https://datatracker.ietf.org/doc/draft-salter-ipsecme-sha3/ From: Russ Housley <[email protected]> Sent: Friday, July 19, 2024 1:49 PM To: Sipos, Brian J. <[email protected]> Cc: [email protected] Subject: [EXT] Re: [COSE] AES-GMAC in COSE Brian: I am willing to assist on the GMAC document. Any reason not to do KMAC as well? See RFC 8702. I would think that KMAC with SHAKE128 (outputs 256 bits with no customization string) and KMAC with SHAKE256 (outputs 512 bitswith no customization string). I am willing to consider other parameter choices if people see a need. Russ On Jul 19, 2024, at 11:28 AM, Sipos, Brian J. <[email protected]> wrote: All, I was looking in the COSE algorithms registry [1] for any existing allocations for GMAC uses but don’t see any. My reason for looking was that in some hardware-accelerated environments AES-GCM is faster than HMAC processing, so a GMAC would also benefit from the acceleration. I expect that a COSE use of AES-GMAC would look similar to the use in CMS [2] except that COSE algorithms typically combine options like authentication tag size into a single code point, so an initial thought would be max-length tags like: AES-GMAC 128/128, AES-GMAC 192/128, AES-GMAC 256/128 Would there be WG interest in allocating GMAC algorithms in the near-term time supporting max-length tags? Thanks, Brian S. [1] <https://www.iana.org/assignments/cose/cose.xhtml#algorithms> https://www.iana.org/assignments/cose/cose.xhtml#algorithms [2] <https://datatracker.ietf.org/doc/html/rfc9044> https://datatracker.ietf.org/doc/html/rfc9044
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