Date: Thu, 29 Mar 2012 05:27:54 +0400 From: Solar Designer <solar@...nwall.com> To: john-dev@...ts.openwall.com Subject: Re: fast hashes on GPU On Thu, Mar 29, 2012 at 05:06:59AM +0800, myrice wrote: > Okay, I am looking at XSHA512. The process is two SHA512_Update with salt > and password then SHA512_Final. Please note that these probably trigger just one call to the underlying SHA-512 compression function (inside OpenSSL) for typical password lengths. The SHA512_Update calls merely buffer data, and the SHA512_Final call actually does the hashing (calls the compression function). You don't need to support password lengths greater than that. You'll likely implement the SHA-512 compression function on its own (or reuse Lukas') and have it inlined. > I see Lukas' cryptsha512.cu already > implements ctx_update for SHA512_Update and sha512_digest for SHA512_Final. > So I can refer to these code on my XSHA512-cuda implementations, is it OK? Yes, you may reuse any code currently in magnum-jumbo. Please just make it clear what you have taken and from where. This should also be reflected on the copyright statements on the source files. > Also, I see in bench.c file, the function benchmark_format takes one salt > and then executes crypt_all. This will make multiple candidate > passwords transferring > to GPU. My first step will implement XSHA512 and tested without modify > bench.c. Next I will make many salts with one bunch of candidate passwords > computing on GPU by modifying the bench.c for testing. I think this makes > sense. This sounds wrong to me. You should not need to modify bench.c at all, not even for testing. It already does both kinds of benchmarks - for "one salt" and for "many salts". Thanks, Alexander
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