phc-discussions - Re: [PHC] pufferfish

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Date: Thu, 27 Mar 2014 20:04:47 -0400
From: Bill Cox <waywardgeek@...il.com>
To: discussions@...sword-hashing.net
Subject: Re: [PHC] pufferfish

On Thu, Mar 27, 2014 at 8:00 PM, Solar Designer <solar@...nwall.com> wrote:
> On Thu, Mar 27, 2014 at 07:38:27PM -0400, Bill Cox wrote:
>> On Thu, Mar 27, 2014 at 7:35 PM, Bill Cox <waywardgeek@...il.com> wrote:
>> > On Thu, Mar 27, 2014 at 7:10 PM, Solar Designer <solar@...nwall.com> wrote:
>> > Great, thanks.  Back on topic, my #1 request for PufferFish would be
>> > having a 4KiB-ish block size with a user-defined repeat count, after
>> > which it would be mixed with another 4KiB block.  This could L1-cache
>> > compute-time harden the algorithm while being effective against GPUs,
>> > couldn't it?  With a low repeat count, it could hash a lot of external
>> > DRAM.  I like the simplicity, but busting out of L1 cache seems
>> > problematic.
>
> Sure, but then pufferfish would be similar to escrypt and TwoCats.

And that would be bad?  :-D

>> P.S.  My #1 request for Escript (sorry, again off topic) would be a
>> SkinnyCat-like stripped down version of the essence of your favorite
>> parts of the algorithm.  I got mine done in something like 30 hours,
>> so there's still time.
>
> I intend to work on something like this much later, way after the PHC
> submission deadline.  I think things like that - additional
> implementations of portions of the functionality - can be added later,
> including as far as PHC is concerned.  I've got better uses for the
> remaining time before the submission deadline.
>
> Alexander

Just in case my opinion matters, I think that's totally a "tweak", and
not a rewrite at all.  I look forward to seeing it.

I had the same thought that doing the two block-size thing would make
PufferFish like Escrypt and TwoCats.  Not doing it seems like a
critical limitation.  PufferFish is cool.  I think it would be cooler
with one more outer loop, though it threatens the simplicity that I
like about it.

Bill