[RC5] First impressions

gindrup at okway.okstate.edu gindrup at okway.okstate.edu
Tue Mar 3 11:44:59 EST 1998


     RC5-56 used randomly selected sequentially assigned strips of the 
     keyspace.
     RC5-64 is using sequential search through (putatively random) 56-bit 
     strips of the keyspace.  Randomly generated blocks are cleverly being 
     redirected to unsearched strips.
     DES-II used sequential assignment.
     
     So, for not-DES-II, the keyspace is being divided up into strips and 
     blocks within the strips are being handed out sequentially.
     In RC5-56, the strip sizes and locations appeared to be random.
     In RC5-64, only two strips have been assigned (that I've noticed).  
     They've bracketed the randomly-generated-block-target so far, but are 
     themselves, ~38% through the keyspace.  There is insufficient data to 
     guess whether strip selections in RC5-64 will be random.
            -- Eric Gindrup ! gindrup at okway.okstate.edu


______________________________ Reply Separator _________________________________
Subject: [RC5] First impressions 
Author:  <rc5 at llamas.net > at SMTP
Date:    1998/03/02 23:23


     [snip]
Another question, based on issuing blocks - how is it allocated...start at the 
beginning and continue until the end, then stop? I know the correct key is 
chosen at random, but averages are it'll be more towards the middle than either 
end...you can guess where I'm heading.
     [snip]
Rossy
     [snip]
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