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The following archive was created by hippie-mail 7.98617-22 on Fri Aug 21 1998 - 17:20:54 ADT
Keith Lockstone (klockstone@cix.compulink.co.uk)
Sun, 26 Jul 98 15:05 BST-1
In-Reply-To: <199807241736.MAA00788@email.plnet.net>
> Actually, RC6 uses RC5's key schedule.
>
> TEA and RC5 were published at the same conference (FSE94, I think),
> so it's not clear which of them used it first. Rivest's designs
> (MD2,MD4,MD5) had previously used commonly-used mathematical
> constants in various places, presumably to avoid charges that they
> were installing trap doors. I don't know who did this first; it may
> have been Rivest. I know that Merkle chose the Snefru, Khafre, and
> Khufu (key scheduling only) S-boxes based on the RAND random number
> tables.
I agree, having checked RC2 and RC5. The only noteworthy constant in RC2
is the s-box used in the key schedule. I'll ask David or Roger next week about
origin of that notion of repetitively adding a number into an accumulator.
I assume that as long as the number is odd, a full cycle will ensue (2**32 in this
case). As an aside - the same could be done in RC4, replacing the incrementing
index register with one that added in 7 bits of key.....
Also, it could be argued that it is a PRNG of similar complexity to a LFSR - requiring a
comparative number of output bits to work out its structure and initial setting!
Regards, Keith.
The following archive was created by hippie-mail 7.98617-22 on Fri Aug 21 1998 - 17:20:54 ADT