Date: Mon, 20 Feb 2012 16:32:32 +0530 From: Deepika Dutta Mishra <dipikadutta@...il.com> To: john-users@...ts.openwall.com Subject: Re: Bitsliced DES thanks for your reply, I will join john-dev list. Regards deepika On Mon, Feb 20, 2012 at 1:41 AM, Solar Designer <solar@...nwall.com> wrote: > On Mon, Feb 20, 2012 at 01:18:21AM +0530, Deepika Dutta Mishra wrote: > > Hi, I am deepika and I just joined your mailing list. Actually I want to > > use bitsliced DES for one of my projects so I wanted to learn about your > > implementation which is said to be the fastest bitsliced DES with > optimized > > sbox expressions. I hope so you will help me in understanding bitslicing > > technique, I have few questions as mentioned below, please do answer. > > Since your questions are about JtR source code, they're slightly more > appropriate for the john-dev list rather than john-users. In fact, > related questions were asked and answered on john-dev recently - you may > want to check the archives of john-dev first. > > > --Does JTR do bitsliced DES using SSE and other vector processing > > instructions only or c codes are also there (though i can't find one)? > > Both. For example, when you build with "make generic", only C code is > used. Ditto when you build for an architecture for which we have no > assembly code nor intrinsics (e.g., when you build on and for SPARC). > Also, when you build for 32-bit x86 without even MMX (e.g., with > linux-x86-any), the C-only bitslice DES code is used for LM hashes. > > > --Is it possible to get sbox optimized expressions as used by JTR? > > Sure, they're in nonstd.c and sboxes-s.c - but in C source code form. > > > Reading from code is very difficult, if mathematical equations can be > found? > > We just did not bother to generate mathematical equations. Why would > we? Well, maybe just to show them in a paper. For actual use, they're > not to be "read" - they just need to be correct (and they are) and they > have certain properties (specified in comments in the nonstd.c and > sboxes-s.c files). > > That said, you may indeed generate them from the C files mentioned above. > > > --Have you published any papers or is there any documentation of your > > implementation which can help in understanding your bitsliced DES code? > > Unfortunately, no. There are only the scarce source code comments and > past discussions on john-dev (where specific questions were asked and > answered). If you have additional specific questions, you may ask those > on john-dev as well. > > > Though I know the basic idea of bitslicing, I want to understand your > > implementation and use it according to my requirement as it is the most > > optimized code. I hope so you will not have any problem in answering my > > questions. > > Sure. On john-dev, please. > > Alexander >
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