From: Timothy Newsham <newsham@wiliki.eng.hawaii.edu>
Date: Thu, 17 Jun 93 11:20:22 PDT
To: jka@ECE.CMU.EDU (Jay Adams)
Subject: Re: fast des
In-Reply-To: <9306171547.AA02951@mustang.ece.cmu.edu>
Message-ID: <9306171820.AA03851@toad.com>
MIME-Version: 1.0
Content-Type: text/plain


> 
> If you were interested in cracking DES, I wonder if you couldn't just
> build the hardware out of FPGAs.  That way, you could make key loading
> and the decrypted data test fast as well.
> 
> - Jay
> 
I tried this on the xilinx 3090 chip.  The tools to handle palasm
didnt seem to be designed to handle a job that size, I had to split
up the file into 3 sub parts (S boxes, key scheduler and everything
else).  I never got it completed but judging by some of the output
I got, it wouldnt have fit on the 3090, which is quite a big
FPGA.  The implementation is straight forward, but there is alot
of juggling you have to do to put it on a 3090 since the S boxes
are slightly bigger than the CLB's tables, and you end up wasting
alot of space when you just need a bunch of xor gates (2 xor's
per CLB, and you need alot of XORs).  Implementation with
standard cell technology would probably be very easy, and
save alot of space too.
(routing the thing is another problem too, since there are
so many permutations,  I am not sure if a near-full-capacity
FPGA would be able to route all the permutations)
                        Tim