[RC5] Another way to win DES-II (joke?)

James Michael Keller jmkeller at radix.net
Fri Jul 31 09:37:14 EDT 1998


> This attack could be used against DES-II-3.  All of the messages start with
> the preamble: "The unknown message is: "  We take the first 56 bits of this
> message, run it through every possible key and store the cyphertext.  When
> the contest starts, we find out who has that cyphertext, and they look up
> the key that goes with it.  If we did this, we could win every DES-II
> contest in... 5 minutes or so.  This assumes we sort the cyphertext.  If we
> don't sort, we will have to wait for each user to search his database for
> the correct cyphertext.

	For out and out winning - yeah we could go about doing hokie things
like this.  However - the point is to be able to apply the same methods
to an unknown message and still crack it....

	If it was really unknown we would be looking for things like 'the' in
the message and then check to see if the rest of the 'clear text' was
'actual text' as well.


-- 
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        James Michael Keller | jmkeller at radix.net
              http://www.radix.net/~jmkeller
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Contents (c)1998 James Michael Keller.  All rights reserved
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