Re: [CFRG] compact representation and HPKE

   Hi Stanislav,

On 2/15/21 11:35 PM, Stanislav V. Smyshlyaev wrote:
> Dear Dan,
>
> >> I can get an I-D out RSN in the expectation that RGLC finishes
> Just a quick comment: the RGLC (the second RGLC) was in August, see 
> https://mailarchive.ietf.org/arch/msg/cfrg/H2xkKDiMVM6x0B8KdGx6Ii5iOO0/, 
> the HPKE draft is one step before the IRSG review.

   Ahhh. OK, then. Even closer.

> >> Yes, I think this is an acceptable way forward.
> Thanks, Dan! No objections against moving forward with the HPKE draft 
> now, right?

   No, none at all. Thanks to the authors for consideration of this and 
finding an
acceptable way forward.

   regards,

   Dan.
> Regards,
> Stanislav
>
>
>
> On Mon, 15 Feb 2021 at 21:42, Dan Harkins <dharkins@lounge.org 
> <mailto:dharkins@lounge.org>> wrote:
>
>
>       Hello,
>
>     On 2/15/21 8:50 AM, Richard Barnes wrote:
>>     Hi folks,
>>
>>     I think Karthik is on the right track here. While the compact
>>     representation undoubtedly has its benefits, it seems like there
>>     is no disagreement that it is not widely supported in either
>>     standards or crypto libraries.  So there is a sizable community
>>     for whom a requirement to use the compact format would render
>>     HPKE unusable.
>>
>>     Given that, I would propose we resolve this issue in the
>>     following way:
>>     * In the current document, define KEMs for the NIST curves using
>>     the uncompressed format.
>>     * If there is a community that is *also* interested in supporting
>>     the compact format, they can define new KEM code points for it.
>>
>>     Would folks be comfortable proceeding on that basis?
>
>       Yes, I think this is an acceptable way forward. I can get an I-D
>     out RSN
>     in the expectation that RGLC finishes and we will soon have an
>     HPKE RFC to
>     update.
>
>       regards,
>
>       Dan.
>
>>
>>     --Richard
>>
>>     On Mon, Feb 15, 2021 at 11:45 AM Karthik Bhargavan
>>     <karthikeyan.bhargavan@inria.fr
>>     <mailto:karthikeyan.bhargavan@inria.fr>> wrote:
>>
>>         I think the idea of having a compact representation of EC
>>         points for use in IoT-like scenarios is an attractive one,
>>         but the core ciphersuites of HPKE should only depend on
>>         standardized and widely-implemented point formats.
>>
>>         In particular, HPKE is certainly not the right place to
>>         standardize a new EC point format, however sensible the
>>         change may seem.
>>         A protocol like EDHOC is laser-focused on small wire messages
>>         and is meant to be implemented by IoT-specific crypto
>>         libraries, and so it makes sense for that protocol to employ
>>         such optimizations.
>>         Perhaps the LAKE working group could drive a IETF/CFRG
>>         standard for x-only EC point representations that are more
>>         generally usable by other protocols?
>>
>>         Having said all that, HPKE is extensible and we do anticipate
>>         extensions to HPKE in the near future, notably for adding PQ
>>         ciphersuites.
>>         I think the best way to proceed for compact HPKE would be,
>>         along the lines of Dan’s suggestion, to propose new KEM
>>         algorithm identifiers for compact encodings of the NIST
>>         curves, and to do this as part of a new CFRG draft as an
>>         extension to HPKE.
>>         I suspect that, beyond the point representation, we may find
>>         other parts of HPKE that would benefit from compaction for
>>         low-bandwidth scenarios.
>>
>>         Best,
>>         Karthik
>>
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>>
>
>     -- 
>     "The object of life is not to be on the side of the majority, but to
>     escape finding oneself in the ranks of the insane." -- Marcus Aurelius
>
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-- 
"The object of life is not to be on the side of the majority, but to
escape finding oneself in the ranks of the insane." -- Marcus Aurelius