Re: [Lwip] I-D Action: draft-ietf-lwig-curve-representations-17.txt

[Rene Struik <[e-mail]>]

Dear colleagues:

I updated the draft, mostly reconsidering iana-related sections. I may 
update once more, depending on what I hear back from expert review.

Small updates:
- added cautionary note re use of signature schemes with message 
encoding/decoding scheme (Section 10.2.1 - ECDSA25519/ECDSA448 with COSE);
- added cautionary language to reflect this in security consideration 
section;
- added step in in Example 4.1, where shared key (curve point) is 
converted to shared secret (octet string). Note: this was already 
spelled out in the COSE/JOSE sections, but thought to add this for 
clarity/avoiding confusion throughout also in specification of ECDH25519 
(Section 4.1);
other:
- added definition of quadratic twist (in curve nomenclature section 
Appendix B.1, with cross-reference to Annex A (added one-liner for each 
of three curve models);
- added one more sentence re twisted curves being a group only under 
certain conditions (triggered by dispelling myths in other standards 
groups) (end of Appendix A.3);
- added informative note on how co-factor DH relates to X25519 and X448 
(end of Section 4.1, resp. Section 4.4), so that readers better 
appreciate differences and similarities;
- tiny word-smything ("i.e.", vs. "e.g." use; "type" vs. "case" language).
   {this is all just simple service to community, so that others can 
reuse definitions in future without much ado}

Rene

On 2020-12-11 11:14 a.m., [e-mail] wrote:
> A New Internet-Draft is available from the on-line Internet-Drafts directories.
> This draft is a work item of the Light-Weight Implementation Guidance WG of the IETF.
>
>          Title           : Alternative Elliptic Curve Representations
>          Author          : Rene Struik
> 	Filename        : draft-ietf-lwig-curve-representations-17.txt
> 	Pages           : 136
> 	Date            : 2020-12-11
>
> Abstract:
>     This document specifies how to represent Montgomery curves and
>     (twisted) Edwards curves as curves in short-Weierstrass form and
>     illustrates how this can be used to carry out elliptic curve
>     computations using existing implementations of, e.g., ECDSA and ECDH
>     using NIST prime curves.  We also provide extensive background
>     material that may be useful for implementers of elliptic curve
>     cryptography.
>
>
>
> The IETF datatracker status page for this draft is:
> https://datatracker.ietf.org/doc/draft-ietf-lwig-curve-representations/
>
> There are also htmlized versions available at:
> https://tools.ietf.org/html/draft-ietf-lwig-curve-representations-17
> https://datatracker.ietf.org/doc/html/draft-ietf-lwig-curve-representations-17
>
> A diff from the previous version is available at:
> https://www.ietf.org/rfcdiff?url2=draft-ietf-lwig-curve-representations-17
>
>
> Please note that it may take a couple of minutes from the time of submission
> until the htmlized version and diff are available at tools.ietf.org.
>
> Internet-Drafts are also available by anonymous FTP at:
> ftp://ftp.ietf.org/internet-drafts/
>
>
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