john-dev - Re: [GSoC] John the Ripper support for PHC finalists

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Date: Sat, 18 Apr 2015 23:59:58 +0200
From: Agnieszka Bielec <bielecagnieszka8@...il.com>
To: john-dev@...ts.openwall.com
Subject: Re: [GSoC] John the Ripper support for PHC finalists

2015-04-18 20:45 GMT+02:00 Agnieszka Bielec <bielecagnieszka8@...il.com>:
> If benchmark encrypts one password on various gws, bencharking will
> give better result than it should be due to less random memory access
> I'm trying to investigate this

It's true. All the time I was receiving wrong benchmarking results
because if we have the same password to encrypt in various GPU's units
function H which randomly accesses the memory works faster due better
coalescing
I made an experiment.
previously I wrote:

> if in fmt_test are 2 records, it is fast
> when I add 10 records with the same cost, it slows down

If I remove function H from the kernel all the time the speed is the same

I've modified the file bench.c to random all keys and I think I've
received  true results now

[a@...er run]$ ./john --test --format=pomelo-opencl --dev=1 --cost=2:2,2:2
Benchmarking: pomelo-opencl, POMELO [POMELO OpenCL (inefficient,
development use only)]... max cost 2
Device 1: Tahiti [AMD Radeon HD 7900 Series]
Local worksize (LWS) 64, global worksize (GWS) 4096
DONE
Speed for cost 1 (N) of 2, cost 2 (r) of 2
Raw:    80313 c/s real, 8192K c/s virtual

[a@...er run]$ ./john --test --format=pomelo-opencl --dev=5 --cost=2:2,2:2
Benchmarking: pomelo-opencl, POMELO [POMELO OpenCL (inefficient,
development use only)]... max cost 2
Device 5: GeForce GTX TITAN
Local worksize (LWS) 64, global worksize (GWS) 8192
DONE
Speed for cost 1 (N) of 2, cost 2 (r) of 2
Raw:    82671 c/s real, 82671 c/s virtual

not as bad ( comparing to previous ) in my opinion

I think that there are 3 possible solutions
1). modify bench.c like I've modified (but, are there a hashes which
cannot receive some specific password values? )
2). spefify more tests cases for fmt_tests (but, sometimes we will
need to pass 100 tests cases and sometimes more)
3). make fmt_main to generate password values if the answer in question is yes

what are your opinions?

BTW I think that I should make some charts comparing the speed of GPU
with CPU in the future

thanks

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