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

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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