[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <20120403160927.GB16518@openwall.com>
Date: Tue, 3 Apr 2012 20:09:27 +0400
From: Solar Designer <solar@...nwall.com>
To: john-dev@...ts.openwall.com
Subject: Re: fast hashes on GPU
myrice -
On Tue, Apr 03, 2012 at 10:34:48PM +0800, myrice wrote:
> 1) In real crack, it seems that the second time we saw a previous salt,
> we receive all salts in the file(Just as shadow file). Is this right?
Yes.
> 2) In benchmark, we only use two salts in fmt_test struct. With many salts,
> we repeat use first two (or one) salts for 0x100(256) times.
Yes. We use two unless there's only one provided in the tests.
> So if we see
> the same salt second time, we cannot do bulk hashing.I am still thinking
> for it. Any ideas?
Yes, this is something I had overlooked when suggesting this approach to
you. Well, actually you can do the bulk hashing there and you'll even
have correct results - but you'll only do it for two salts, which is not
exactly "many", so the benchmark result won't be very meaningful.
You may revise the condition to be keys_changed && saw_same_salt_again.
(keys_changed is set in set_key() as we discussed before.) This
condition will be true only after bench_set_keys() has been called for a
second time, so by that point you'll have the correct number of salts
recorded (including duplicate salts, which are present in benchmarking
only).
Anyway, as I wrote to you earlier today, I don't expect any of this to
result in much speedup (assuming correctly tuned max_keys_per_crypt in
either case).
Instead, you may focus on offloading hash comparisons to GPU.
> I tested new code on GTX580(THREADS 480, BLOCKS 1024):
You could try THREADS 512 there.
> Benchmarking: Mac OS X 10.7+ salted SHA-512 CUDA [64/32]... DONE
I suggest that you put "CUDA" in place of "64/32", and remove " CUDA"
from "Mac OS X 10.7+ salted SHA-512 CUDA".
The bits_used/bits_total notation was never meant to include let's say
bits_desired in the bits_used portion. ;-)
> Many salts: 34065K c/s real, 34065K c/s virtual
> Only one salt: 23359K c/s real, 23130K c/s virtual
That's a bit slower than what I had on GTX 570 o/c (which should be of
similar speed to a GTX 580 at stock clocks). I think some of the other
optimizations/hacks I was making is not yet in your code. I'll test
your newer code and see.
Thanks,
Alexander
Powered by blists - more mailing lists
Confused about mailing lists and their use?
Read about mailing lists on Wikipedia
and check out these
guidelines on proper formatting of your messages.
