Date: Tue, 6 Mar 2012 09:11:04 +0200 From: Milen Rangelov <gat3way@...il.com> To: john-dev@...ts.openwall.com Subject: Re: RAR format finally proper Great :) Did the memory buffering improve things a lot with your code? I was surprised to find out it does not improve performance a lot here :( It would be great if you can find out some way to improve checking and share it of course :) As per AES/OpenSSL, I read somewhere they implemented runtime AES-NI detection/use. Though I don't think this have made it into the debian packages I use yet. It might improve things a lot. I also scan the archive to find the smallest file to crack. I went a bit too far by refusing to crack an archive if there is no file smaller than 4MB in it, it just becomes so slow. I am really considering to do some bulk AES decryption on GPU, however memory and bus bandwidth requirements become so bad :( On Tue, Mar 6, 2012 at 2:16 AM, magnum <john.magnum@...hmail.com> wrote: > Thanks to Milen's advice I am now committing a working version of RAR > format that does not spawn unrar yet can attack all modes. It was fairly > simple to get the clamav code running, I changed it to work on a memory > buffer instead of a file handle, and removed legacy RAR stuff and > autoconf macros. It now decrypts and CRC's on the fly. I also added OMP > to the format. We do not support solid archives yet but I think that's > doable with a little research (it's supported by the clamav code). > > I can see now the AES decryption get significant with larger files. > For small files the speed is about the same as for the -hp mode. I > tried a 2 MB file and speed went down from ~36 c/s per core to one-digit > figures :-/ But rar2john will now scan the whole archive and pick the > smallest file possible. > > There are a lot more optimisations possible. I'm not sure the unpack > code bails out immediately on any kind of bad data, it may continue > longer due to laxed checking. But in many cases it does bail out early, > it averaged rejecting after 41% of the available data in a small test > with various files. Anyway we now have a decent base to work from so > things will only get better. > > We still need OpenCL of course. Samuele, hit it! :-) > > Note that input files created with any older version of rar2john need to > be recreated. > > magnum > > Content of type "text/html" skipped
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