Date: Thu, 18 Jul 2013 09:55:56 +0530 From: Sayantan Datta <std2048@...il.com> To: john-dev@...ts.openwall.com Subject: Re: md5 hash comparisons Hi, On Thu, Jul 18, 2013 at 6:00 AM, Michael Samuel <mik@...net.net> wrote: > I had quite a bit of success with this approach with some otp-md5 > stuff I did, first because branches on GPUs are(/were?) really > expensive and second because gpu->host transfers are async so the gpu > can be computing the next batch while the transfer occurs. > This could have been a good idea for small number of hashes. But as solar mentioned we will be checking more than a million hash against the millions generated. I think a single cpu core will bottleneck at some point. What I intend to do is use local memory for first 2 bitmap checks each of size 4KB so that they fit inside LDS . Then the last two bitmap check will use bitmap stored in global memory each of size 256MB. However I did a little math which shows 99% of hashes are going through the first two test. Mathematically the whole bitmap idea seems to be ineffective. But the plus point is that the math I did was based on the assumption that all possible hashes md5 hashes are loaded. But clearly this will never be the case. Regards, Sayantan Content of type "text/html" skipped
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