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Date: Thu, 16 May 2013 14:09:54 +0200
From: magnum <>
Subject: Re: password generation on GPU

On 16 May, 2013, at 13:28 , Solar Designer <> wrote:
> On Thu, May 16, 2013 at 12:48:50PM +0530, Sayantan Datta wrote:
>> In this implementation of mask-mode the key is generated outside the
>> format.  However in the PG-test branch we were generating the keys inside
>> the format using GPU . So how do I start implementing the mask mode? Should
>> we generate the keys globally outside the format using a GPU ?
> Oh, at first I misread what you wrote above.  You're asking not whether
> to generate keys on host vs. GPU (the short answer to which is that we
> should do both of these things), but whether to do the GPU portion of
> key generation inside the format or with code shared between formats.
> So far, we only considered doing it from the same kernels that do the
> crypto, so we'd have duplicate implementations of the GPU side of mask
> mode (one for each fast hash format).  I think that for mask mode this
> is in fact what we should be doing, and those duplicate implementations
> will end up having enough format-specific optimizations for the code
> "duplication" to be worth it.  (Ditto for code responsible for comparing
> computed vs. loaded hashes, using bitmaps and such.)  We may also have
> generic implementation(s) (or portions thereof), to be #include'd from
> multiple per-format OpenCL kernels.  Using separate kernels (with
> communication via global memory?) is likely slower.

A kernel can call another kernel iirc so it might not be too bad. Maybe try it out? It could simplify shared use.


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