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Date: Wed, 18 Jul 2012 10:28:17 +0530
From: Dhiru Kholia <>
Subject: Re: Keychain format OpenCL implementation, please review

On Tue, Jul 17, 2012 at 11:46 PM, Solar Designer <> wrote:
> On Tue, Jul 17, 2012 at 10:02:05PM +0530, Dhiru Kholia wrote:
>> Speed is 132K c/s on ATI 6970. It is roughly 300x faster than
>> single-core CPU version (AMD X3 720). Hopefully, I haven't screwed
>> things up ;)
> I guess this means that your CPU code is a lot slower than it can/should
> be. ;-)  And your 140K c/s figure for 7970 (mentioned elsewhere)
> suggests that you might still be spending much time in CPU code, which
> is why changing the GPU makes little difference.

Yes, 3DES decryption is done on the CPU. I will try accelerating 3DES
operations using OpenMP.

> IIRC, this is PBKDF2-HMAC-SHA-1 with 1000 iterations producing a 3DES
> key, right?  If so, I think that's roughly the same as 2000 iterations
> (since SHA-1's output size is not enough for a 168/192-bit 3DES key
> as-is).  For MSCash2, we have 10240 iterations.  So you should have 5
> times higher speed, or about 500k c/s on 7970.

I thought 132K c/s was good enough but now I see that way more speed
can / should be achieved.

> Also, I notice that your code does not use bitselect() and rotate() yet -
> see the kernel we use for MSCash2 and merge those changes.

Will take a look. Thanks!


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