Date: Thu, 09 Aug 2012 01:36:04 +0400 From: Pavel Semjanov <pavel@...janov.com> To: john-dev@...ts.openwall.com Subject: Re: Patch for pkzip_fmt_plug.c from jumbo-6 > Both of the files are plain archives without encryption. Maybe you sent > the wrong ones? I've just explained why I can't to it in previous message. > >>> BTW, could you by any chance help us with better early rejection >>> in the RAR format? I'm just asking :) >> >> It's quite simple. In CPU code, the block is checked for LZ type or >> PPM type. If it's LZ, the Huffman table test is used, like ZIP does. > > Thanks! So I can pre-test it more or less exactly like pkzip do? I > thought there would be differences between LZ2 and LZ. Does cRARk do > this fairly similar to Jim's pkzip code? Any codes for Huffman table check are fairly similar ;) > > Regardless, I think I'll need Jim's help here. > >> If it's PPM, the reset bit should be set and MaxMB size can't be >> grather than 7f. If yes, the decompression begins and password is >> rejected quite fast in RAR PPM code. > > OK. So that is what, 9 bits in total? Then I can reject 75% [of PPM] > without even calling rar_unpack29(), right? Hmm... 3 bits, right? One for PPM, one for reset, one for MaxMB. So, 7/8 of passwords can be rejected. > >> In GPU code, only standard parameters (i.e, -m0 .. -m5) are allowed. >> This makes very effective early reject by checking MaxOrder and MaxMB >> sizes. > > I suppose I should transfer a portion of the file to GPU so I can reject > immediately. Hm, but then I'd need to implement AES on GPU too. OpenSSL code (which is very similar to original optimized code) runs fine of CUDA and OpenCL. I am > very impressed with how cRARk is totally immune against file size. But > I'll try to implement this without changing my Key-derivation-only > kernel, as a first step. > > I'll try this soon, lots of thanks! > > magnum > > -- SY / C4acT/\uBo Pavel Semjanov _ _ _ http://www.semjanov.com | | |-| |_|_| |-|
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