phc-discussions - A GPU friendly hashing algorithm

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Message-ID: <541CA7D9.6070501@ciphershed.org>
Date: Fri, 19 Sep 2014 18:02:01 -0400
From: Bill Cox <waywardgeek@...hershed.org>
To: discussions@...sword-hashing.net
Subject: A GPU friendly hashing algorithm - gpuhash

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

After reading so many good ideas in detail during my reviews, I wanted
to go back and apply some of what I'd learned in a new password
hashing algorithm.  This is not an entry for the competition, but it
might be fun to discuss.

I started out trying to include Antcrypt's idea with many different
hash functions.  I found it slowed down my defense quite a bit, maybe
3X in speed, making it harder to hurt GPUs as well as I wanted to.
Also, I wanted to include Wolfram's Rule 30 which I read about in the
Schvrch attached paper.  Unfortunately, these simple
single-dimensional cellular automaton run great on GPUs.

So, here's gpuhash, in a proof-of-concept form.  It is *GPU friendly*
on purpose.  The idea is that it might lead towards a good hashing
function to run in the Parallel entry, in that it might run a lot
faster than SHA512 on a GPU, and not have too much speed-up in an ASIC.

Gpuhash currently has a 32x32 bit state in a grid.  Rule 30 is applied
on each column 16 times, and then I "diaglonalize" it, by
right-shifing each row by it's row number.  I then apply Rule 30 on
each row 16 times.  I know that odd-numbers here are better, but I
wanted to see what this would do.  It seems to mix well.

I read somewhere that cell-phone GPUs have 32 32-bit registers and
that operations can be applied to either to rows or columns of bits.
I am hoping this hash fits cell-phone GPUs well.

The code is attached.  Enjoy!

Bill
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TeVuk0QcYn4mue/ODHUUwvRk0xFm9STV7BYLXczL+OeGyqrLt4Yu1NicNqUDKd65
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DQNbhMFQS725dIXtvjlU7TnCKaa/DS0Nxc4UgURqEY1FYPC4/UL7K5JZcmDthjdG
Tx3CqgyV1clb2Z+oPasL
=xU2m
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Download attachment "gpuhash.tar.gz" of type "application/gzip" (7439 bytes)