[ This is an article that I just posted to sci.crypt ] In describing Blowfish Bruce Schneier mentioned that it achieves avalanche after the 3rd round, and after each two subsequent rounds (5, 7, 9, ...). (I understand 'avalanche' to mean that each bit of the key has affected each bit of the data being encrypted. Do I understand correctly?) He also mentioned the possibility of decreasing the number of rounds in Blowfish from the current 16, in order to improve the speed. My question is, would it be sensible to do it with an odd number of rounds? If 10 rounds were a consideration, then why not go on to 11 to get the 5th complete avalanche? Or perhaps it would suffice to stop after 9 rounds, after the 4th complete avalanche? Is a whole number of avalanches a desirable feature? Would an odd number of rounds throw a spanner into the key schedule? Also, how would this relate to the modified algorithm, Blowfish-SK? I think I have now made my lack of expertise amply apparent. :-) [ ObNoise: does it take Nukes to end the jim bell/Alan Olsen flamewar? ] [ ObRating: this post is rated G because it does not contain the words shit, piss, fuck, cunt, cocksucker, motherfucker, or tits. ] Hoping these are not stupid questions, -- David R. Conrad, conrad@detroit.freenet.org, http://www.grfn.org/~conrad Hardware & Software Committee : finger -l conrad@grfn.org for public key Key fingerprint = 33 12 BC 77 48 81 99 A5 D8 9C 43 16 3C 37 0B 50 No, his mind is not for rent to any god or government.