Re: [Lwip] I-D Action: draft-ietf-lwig-curve-representations-09.txt

Rene Struik <> Tue, 10 March 2020 16:20 UTC

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From: Rene Struik <>
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Date: Tue, 10 Mar 2020 12:20:51 -0400
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Subject: Re: [Lwip] I-D Action: draft-ietf-lwig-curve-representations-09.txt
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Dear colleagues:

I uploaded a revised draft-ietf-lwig-curve-representations-09 draft. 
Main changes compared to the 08-draft:
a) inclusion of Curve448 and corresponding Wei448 curve, so that code 
points for those could be requested. Please note that both Wei25519 and 
Wei448 are included with draft NIST SP 800-186 and can be used with 
draft FIPS 186-5 (both published Oct 31, 2019 [~3 1/2 months after the 
08-draft]). I tried to include this in a modular way without being too 
disruptive to what has been in previous versions of the draft. Almost 
all document changes are due to this.
b) some small edits in the appendices, so as to make this more useful 
for cross-referencing if people wish to (e.g., definition of 
higher-order curve point in Appendix B.1; some expansion of curve 
operations after the y-coordinate recovery remark in Appendices C.1, 
C.2, C.3; illustration of how one could avoid small subgroup points in 
mappings of Appendix K).
c) fixed some small copy-and-paste glitch in the test vectors for 
Wei25519.-3 (Y1 coordinate). {Note: this glitch was in version 02 of the 

For details on how this draft tries and accommodate the SecDir and 
IoTDir review comments, please see the email responses sent earlier today.

Final notes:
(1) I did notice three tiny editorial glitches with the new 09 document, 
which I wil fix in due course.
(2) I will have someone else triple-check all numerical values in the 
entire document (I did redo those myself, thereby uncovering (c) above, 
but think another pair of eyes would be good).

Best regards, Rene

On 3/9/2020 7:57 PM, 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-09.txt
> 	Pages           : 105
> 	Date            : 2020-03-09
> 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:
> There are also htmlized versions available at:
> A diff from the previous version is available at:
> Please note that it may take a couple of minutes from the time of submission
> until the htmlized version and diff are available at
> Internet-Drafts are also available by anonymous FTP at:
> _______________________________________________
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