[RC5] C DES core

James Kew JK at langley.softwright.co.uk
Thu Jan 22 09:07:53 EST 1998

Mary Conner wrote:
>There are many C implementations of DES encryptor/decryptors available,
>and one is not all that hard to write given the DES algorithm.  What
>are in short supply, and need some real code jockeying, are
>implementations designed to do exhaustive brute force cracking.
I don't doubt that this is true, but I feel strongly that d.net should
have readied clients for as many architectures as possible, using a
generic C DES core, as early as possible. There's an old software
engineering adage that I think is very applicable here: "make it work,
then make it work fast". We *still* have many clients that aren't
working on DES.

Let's not forget that as well as a crypto problem (crack as many DES
blocks as possible per day) d.net also has a social engineering problem:
lots of clients that were ready and willing to crack DES have been left
out in the cold for a long time. This doesn't build enthusiasm and
commitment to the cause!

A slow-but-functional generic C core that could be easily dropped into
all the client builds would have had these clients cracking from day
one. Yes, it may not be as fast as the opimised assembly cores, but you
do those *next*.


>On Tue, 20 Jan 1998 gindrup at okway.okstate.edu wrote:
>>      Dumb question:
>>      Could not the DES encryptor/decryptor source in Schneier's Applied 
>>      Cryptography have been used?  There might be some right-to-use 
>> issues, 
>>      but I would doubt it given the amount of trimming that would have 
>> been 
>>      done to turn it into a 1-block decryptor accepting IV.
>>             -- Eric Gindrup ! gindrup ! gindrup at Okway.okstate.edu
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