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Date: Thu, 6 Dec 2012 02:16:21 +0530
From: Sayantan Datta <std2048@...il.com>
To: john-dev@...ts.openwall.com
Subject: Re: bitslice DES on GPU

On Thu, Dec 6, 2012 at 1:08 AM, Solar Designer <solar@...nwall.com> wrote:

> We need to be patching binary, not source.  For example, you could find
> the pointers to patch by looking for their known values, then making
> sure their count is as expected.  You'd record their addresses in an
> array.  Then reuse that array to patch them each time a new salt it set.
>

I'm confused!! Do you mean we need to patch the binaries that we get after
a call to clBuildProgram() ? OpenCL binaries are generally elf objects and
require additional dependencies to parse them. Or do you mean we should try
to avoid disk i/o caused by patching sources directly? Please clarify!!

Curious.  How much memory is consumed per salt?  How much is consumed
> when all 4096 salts are present?  And how long does it take to build the
> 4096 kernels?  (If this takes too long to measure, then provide the
> number e.g. for 41 or 410.)


For instance when 35 different salts are loaded ,john consumes a total of
100MB of RAM. Also the test suit containing 1500 hashes consumes around 1.2
- 1.3 GB memory and takes around 1050 seconds to complete the test. Given
that most of the time is spent on building kernels, 4096 different salt
should consume around 4GB of memory and take around 20-30 minutes to build
all the kernels.

Regards,
Sayantan

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