Brian:

If you are willing to add KMAC128-KDF and KMAC256-KDF (see Section 5.2 of RFC 
9688), then I'm happy to assist.

Russ


> On Nov 20, 2024, at 9:16 AM, Sipos, Brian J. <[email protected]> wrote:
> 
> All,
> I now have a first non-internet-draft version of a GMAC and KMAC registration 
> [1] available for browsing and initial feedback. After that feedback I can 
> post this as a proper internet draft. Right now, the code point registrations 
> follow existing AES-related parameters for 128, 192, 256 -bit keys and 
> full-length tags. I don’t have particular interested in shortened tag lengths 
> so didn’t put in allocations for them like some of the existing COSE MAC 
> algos have. I also don’t have strong feelings about useful key lengths.
>  
> John, I understand your comments about the IV uniqueness vs. randomness and 
> if you have some specific language for Section 2.1 that is welcome. Otherwise 
> I will add a requirement to forbid random IV values. Is there any stronger 
> recommendation for how to generate non-random IVs?
>  
> Russ, if you would like to be added as a coauthor and want to steer the KMAC 
> details just let me know from where I can take your up-to-date contact 
> details. Right now, this allocation does make use of the KMAC customization 
> string similar to the IPsec draft. But if there is some guidance or benefit 
> to avoiding the customization that would be useful to know.
>  
> [1] 
> https://briansipos.github.io/cose-gmac-kmac/draft-sipos-cose-gmac-kmac.html
>  
> From: John Mattsson <[email protected] 
> <mailto:[email protected]>> 
> Sent: Thursday, October 31, 2024 12:47 PM
> To: Sipos, Brian J. <[email protected] <mailto:[email protected]>>; 
> Russ Housley <[email protected] <mailto:[email protected]>>
> Cc: [email protected] <mailto:[email protected]>
> Subject: Re: [COSE] Re: [EXT] Re: AES-GMAC in COSE
>  
> APL external email warning: Verify sender [email protected] 
> <mailto:[email protected]> before clicking links or attachments
>  
> 
> Hi,
>  
> Specifying KMAC is a great idea, we (Ericsson) are planning to transition as 
> much as possible to SHA-3/SHAKE/cSHAKE/KMAC in the transition to PQC, which 
> ML-KEM and ML-DSA use internally. I am happy to help with any introduction of 
> SHAKE and KMAC in IETF protocols. I assume the document will specify KMAC128 
> and KMAC256. A remaining question is what the tag length should be and if 
> several tag lengths should be specified. 
>  
> (Regarding the IPsec draft: I don’t see any use of HMAC-SHA3-256, 
> HMAC-SHA3-384, HMAC-SHA3-512, these are very inefficient constructions. I 
> don’t think there are any reasons to use anything else than KMAC. Similarly, 
> the requirement on signature algorithms should be SHAKE. Also, NIST is soon 
> disallowing SHA3-224.)
> https://datatracker.ietf.org/doc/rfc8692/
> https://csrc.nist.gov/pubs/sp/800/131/a/r3/ipd
>  
> Regarding AES-GMAC, I think AES-192 could be skipped. I agree the tag length 
> should be 128-bits for GMAC. In addition to stating “Within the scope of any 
> content-authentication key, the AES-GMAC nonce value MUST be unique.” I think 
> the draft should explicitly state that random nonces MUST not be used. As I 
> brought in my comments to NIST, SP 800-38C (CCM) states that the nonce shall 
> be unique but there are still implementations that use CCM with a 11-byte 
> random nonce as the default…
> https://csrc.nist.gov/csrc/media/Projects/crypto-publication-review-project/documents/initial-comments/sp800-38c-initial-public-comments-2024.pdf
>  
> Cheers,
> John
>  
> From: Sipos, Brian J. <[email protected] <mailto:[email protected]>>
> Date: Thursday, 31 October 2024 at 16:56
> To: Russ Housley <[email protected] <mailto:[email protected]>>
> Cc: [email protected] <mailto:[email protected]> <[email protected] 
> <mailto:[email protected]>>
> Subject: [COSE] Re: [EXT] Re: AES-GMAC in COSE
> 
> 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] <mailto:[email protected]>> 
> Sent: Friday, July 19, 2024 1:49 PM
> To: Sipos, Brian J. <[email protected] <mailto:[email protected]>>
> Cc: [email protected] <mailto:[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] 
> <mailto:[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
> [2] https://datatracker.ietf.org/doc/html/rfc9044

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