Re: [Cfrg] ed448goldilocks vs. numsp384t1 and numsp512t1

Ilari Liusvaara <ilari.liusvaara@elisanet.fi> Tue, 21 October 2014 11:09 UTC

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Date: Tue, 21 Oct 2014 14:09:10 +0300
From: Ilari Liusvaara <ilari.liusvaara@elisanet.fi>
To: Michael Hamburg <mike@shiftleft.org>
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Subject: Re: [Cfrg] ed448goldilocks vs. numsp384t1 and numsp512t1
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On Mon, Oct 20, 2014 at 03:48:48PM -0700, Michael Hamburg wrote:
> 
> On Oct 20, 2014, at 2:24 PM, Ilari Liusvaara <ilari.liusvaara@elisanet.fi> wrote:
> > 
> > On Sat, Oct 18, 2014 at 08:30:17PM -0000, D. J. Bernstein wrote:
> 
> >> Also signature verification:
> >> 
> >>    624000 cycles claimed: numsp384t1 (ed-384-mers),    ~2^192 security.
> >>    729152 cycles measured on h6sandy: ed448goldilocks, ~2^224 security.
> >>   1320000 cycles claimed: numsp512t1 (ed-512-mers),    ~2^256 security.
> > 
> > Here Ed448 seems to be slightly slow for some reason.
> > 
> > I would have estimated (on very dubious grounds) ~680k.
> 
> For verification, Goldilocks has to decompress and ECCLib doesn’t,
> which costs almost 10%.

Signature verification uses double-sclar multiply, right?

Is your ds multiply constant-time? Because the one in ECClib
apparently isn't (everything else should be).


-Ilari