Re: [Cfrg] Fwd: Re: Safecurves draft

Robert Ransom <rransom.8774@gmail.com> Sat, 11 January 2014 16:10 UTC

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From: Robert Ransom <rransom.8774@gmail.com>
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Subject: Re: [Cfrg] Fwd: Re: Safecurves draft
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On 1/9/14, Manuel Pégourié-Gonnard <mpg@elzevir.fr> wrote:
> On 09/01/2014 17:38, Robert Ransom wrote:

>> A Curve25519 (Montgomery-line ECDH) implementation will generally use
>> a ladder with no precomputed table because Montgomery's formulas are
>> so much faster that way.
>>
>> An Ed25519 (Edwards curve, typically signature-related) implementation
>> will generally use either [...]
>>
> Right. Since I only implemented the Montgomery version so far, I've got the
> nasty habit of thinking mainly about that form.
>
> But, unless I'm mistaken, it seems to me we agree on the main point here:
> "no
> data-dependant branches or memory access" is a property of the
> implementation,
> not of the curves.

Yes.


Robert Ransom