Date: Tue, 27 Mar 2012 13:22:09 +0400 From: Solar Designer <solar@...nwall.com> To: john-dev@...ts.openwall.com Subject: Re: Hello, interested on slow hash and fast hash on GPU On Mon, Mar 26, 2012 at 04:48:26AM +0800, myrice wrote: > 1) I read papers you recently posted. And I emailed author of qhasm-cudasm > for requesting the tool. Please let us know if/what you hear back. (BTW, I think that multiple authors contributed to it.) > 2) The bitslice implementations of SHA-256 or SHA-512 on GPUs are worth > discussing. I read your bitslice implementation of MD5. It takes advantages > of sse2 to compute MD5 hashes at one time. Now raw-sha256-cuda > implementation already use SIMD and/or bitslice. Just where did you find any "SIMD and/or bitslice" in the raw-sha256-cuda implementation? While the compiler can auto-vectorize (at least theoretically), I don't see that in the source code. We only have non-bitslice implementations of these currently (except for my experiment with MD5 on CPUs that you saw), and it is not known whether non-bitslice SIMD or bitslice will be faster (it may vary by target architecture, etc.) This is why I suggest that whoever works on this should try both approaches. My guess is that non-bitslice (with SIMD where appropriate) will be faster on currently common CPUs/GPUs (speaking of SHA-256 and SHA-512), but it does not hurt to try bitslice as well. > I tried use more > threads(than now just 1) to compute one hash. However, the data dependence > make it hard to implement. I am looking forward ideas of optimization. You should be computing many hashes, not one. > 3) As you suggested, I am starting write DES format on cuda. I will make > another post to track my progress and clarify questions on it. OK. This was not exactly my suggestion to you - I was merely answering questions on what remains to be done in terms of JtR/GPU, and the DES stuff is among tasks that haven't been approached yet (as it relates to JtR/GPU only). Alexander
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