Re: [Cfrg] draft-ladd-safecurves-02

Dan Brown <> Sat, 11 January 2014 00:37 UTC

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From: Dan Brown <>
To: Watson Ladd <>, Alyssa Rowan <>
Thread-Topic: [Cfrg] draft-ladd-safecurves-02
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Date: Sat, 11 Jan 2014 00:37:04 +0000
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Subject: Re: [Cfrg] draft-ladd-safecurves-02
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I didn't agree with all the arguments on the Safecurves URL, at least when I last read it a few months ago. Nor did I agree with all DJB said on the TLS WG list.

I'm going to try to write up to CFRG my disagreements soon.

Maybe I'm old school, but I'd expect references to be stable and dated. Even if CFRG consensus (eg all minus me) fully agrees with the site today, the site could change, in a way not expected.

The CFRG consensus may also be to move ahead with these curves, without agreeing fully with the site.

So it might help for the spec to state the CFRG's rationale for accepting these curves.

More practically, ideal would be to advise users of the advantages and disadvantages of these curves, over others.

From: Watson Ladd
Sent: Friday, January 10, 2014 6:31 PM
To: Alyssa Rowan
Subject: Re: [Cfrg] draft-ladd-safecurves-02

On Fri, Jan 10, 2014 at 11:48 AM, Alyssa Rowan <> wrote:
> Hash: SHA512
> On 10/01/2014 19:11, Watson Ladd wrote:
>> Added: explicit formulas and a point format (big endian with a bit
>> for the missing coordinate).
> Fair enough. (Cofactors were also added, by the way.)
>> The name is now the Chicago curves.
> As good as any other.
> Comments:
> • Typo in end of section one: Weierstrass, not Weierstrauss.


> • I think it'd be a little more helpful if section 2 were split into
> two sections: the Montgomery curves, and the Edwards curves. That'd
> make it much more apparent which curves are applicable to which
> sections in 3 and 4.

I'll think about a clean way to do this. Of course, you can use
isogenies to convert
between all of these forms.

> • Pretty please can we have Curve1174 as well?


Anymore suggestions? This next one it would be nice to get Last Call on.
> Other than that, no more comments.
> E-521's passed all tests, by the way, as expected (and it seems was
> obviously rigid enough that three groups actually came up with the
> exact same curve!).
> I see no particular reason to hold this up.
> - --
> /akr
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