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Message-ID: <CALapUyF4XMQDXiupz1__eF70ENhwLdZxWu4ECz4Sp0kHpkxCGA@mail.gmail.com>
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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