Re: [CFRG] I-D Action: draft-irtf-cfrg-hash-to-curve-16.txt

My two cents: I would prefer not to specify it as a squeeze behavior,
especially since that’s also complex and even fewer implementations
need to do it in practice.

Maybe we could specify that implementations of hash_to_field may be
restricted in terms of what counts they support, and that supporting
{1,2} suffices for all the uses in this spec?

Or we could specify that hash_to_field may be internal?  Then you
definitely wouldn’t need to implement it for all N, just for the cases that
actually come up.

Regards,
— Mike

> On Jan 10, 2023, at 1:24 PM, Jeff Burdges <burdges@gnunet.org> wrote:
> 
> 
> Appears hash_to_field and expand_message should not involve an arbitrary
> counter.  Instead, they should either (a) be specified in terms of some
> squeeze behavior, or else (b) have the counter restricted somehow.  I'm
> sure (b) suffices since hash_to_field needs a counter of only one or
> two. 
> 
> In fact, you could merely say the counter is a constant, not a runtime
> variable.  An implementation that uses a constant is then compliant,
> while an implementation that uses a runtime variable "exceeds" the spec,
> which is fine.
> 
> As is, this adds implementation complexity for platforms without a
> dynamic allocator, ala https://github.com/arkworks-rs/algebra/issues/572
> 
> Best,
> Jeff
> 
> 
> 
> On Jun 15 2022, at 8:43 am, internet-drafts@ietf.org wrote:
> 
>> 
>> A New Internet-Draft is available from the on-line Internet-Drafts directories.
>> This draft is a work item of the Crypto Forum RG of the IRTF.
>> 
>>       Title           : Hashing to Elliptic Curves
>>       Authors         : Armando Faz-Hernandez
>>                         Sam Scott
>>                         Nick Sullivan
>>                         Riad S. Wahby
>>                         Christopher A. Wood
>> 	Filename        : draft-irtf-cfrg-hash-to-curve-16.txt
>> 	Pages           : 175
>> 	Date            : 2022-06-15
>> 
>> Abstract:
>>  This document specifies a number of algorithms for encoding or
>>  hashing an arbitrary string to a point on an elliptic curve.  This
>>  document is a product of the Crypto Forum Research Group (CFRG) in
>>  the IRTF.
>> 
>> 
>> The IETF datatracker status page for this draft is:
>> https://datatracker.ietf.org/doc/draft-irtf-cfrg-hash-to-curve/
>> 
>> There is also an HTML version available at:
>> https://www.ietf.org/archive/id/draft-irtf-cfrg-hash-to-curve-16.html
>> 
>> A diff from the previous version is available at:
>> https://www.ietf.org/rfcdiff?url2=draft-irtf-cfrg-hash-to-curve-16
>> 
>> 
>> Internet-Drafts are also available by rsync at rsync.ietf.org::internet-drafts
>> 
>> 
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> 
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