phc-discussions - Re: [PHC] A must read...

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Date: Wed, 15 Jan 2014 12:45:18 -0500
From: Bill Cox <waywardgeek@...il.com>
To: discussions@...sword-hashing.net
Subject: Re: [PHC] A must read...

On Wed, Jan 15, 2014 at 12:38 PM, Peter Maxwell > Well, using floats
in cryptography is not exactly a new idea but I suspect
> it does have some portability problems, e.g. there's implementation of
> Bernstein's poly1305 using floating point - http://cr.yp.to/mac/53.html -
> although I haven't actually sat down to look at it... it's sitting fairly
> far down on my to-do list.

There are also compiler specific issues.  I've had considerable
trouble over the years forcing various compilers to not optimize my
floating point in any way to insure that I get the same answer on all
machines.

I like the idea of floating point, but I doubt it's worth the excess
trouble we'll run into.  32x32 -> 32 Integer multiply seems solid and
pervasive enough.  Besides that, it's fast in our devices even
compared to a custom ASIC, and it's a great operation for mixing bits,
at least when one op is odd.

Bill