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Date: Thu, 19 Jul 2012 21:34:05 +0530
From: Dhiru Kholia <>
Subject: Re: fast pbkdf2-sha1 OpenCL kernel

On Thu, Jul 19, 2012 at 9:08 PM, Lukas Odzioba <> wrote:
> 2012/7/19 Dhiru Kholia <>:
>> I am looking for a fast pbkdf2-sha1 OpenCL kernel which can handle
>> passwords of length 20, salt size 20 and can output key length of 66.
>> 1) Can the wpa-psk kernel work with password size of 20? If not, can
>> it be modified to do the same? I need this for ODF kernel.
>> 2) Currently the output of wpa-psk kernel is 32 bytes, can this be
>> increased to 64 + 2 (= 66)? I need this for ZIP AES kernel.
>> Jim, does you pbkdf2 kernel meet these requirements? Can it be
>> modified to do so?
>> I have written a pbkdf2 kernel which meet all these requirements but
>> it is 5x slower than Lukas's code on CPU and on GPU it is unusable
>> (super super slow).
> I can prepare for you kernel meeting that requirements, however for
> OpenCL i suppose that Sayantan's code is faster.
> Make a decision which kernel you want to use, and let me know then I
> can start working on more general PBKDF2-SHA1 kernel than this in
> wpapsk.

To accelerate zip and ODF formats, a more general PBKDF2-SHA1 kernel
is needed (passwords of length 20, salt size 20 and output length 66).

Your code also works on CPU with no problems. Hence I picked your code
to start with and will stick with it. It can be made faster later on.
It is already 5x faster than my kernel!

Start already ;)


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