CDR: Re: Permutations in DES

[Kevin Elliott]

At 10:13 -0400 9/7/00, Trei, Peter wrote:
>	For brute force key search, the initial permution can effectively be
>	factored out, and neither speeds nor impedes the search. This was
>	done by all of the keysearch apps used in the RSA Symmetric DES
>	Challenges.

Do you have a link and/or expanded information on the specifics?

>	I (this was before I worked for RSA) also described an extremely
>fast
>	method to generate and iterate key schedules which was also widely
>	used, reducing key schedule management from 90% of cpu to less
>	than 10%.

Does this method work for apps that are generating and testing lots 
of keys or does the initial key generation step still have to be 
undertaken?  The whole point of the blowfish technique was to 
increase the attackers required effort.  It was basicly assumed that 
valid users would simply store the expanded key.  Is their a link 
somewhere to more information on this technique or could you expand 
on it?
-- 

Kevin "The Cubbie" Elliott 
<mailto:kelliott at mac.com>                             ICQ#23758827
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