Harvey Rook writes:
It's a little bit more complicated than that. RC-6, which also uses data dependant rotations is patent free.
Wasn't that a requirement for being an AES submission? As you may have guessed, I'm not a fan of permitting software to be patented. Particularly things like RSA for which obvious prior art existed, and the plethora of microprocessor patents which cover things like doing branch prediction and switching instruction sets in absurdly obvious and simple ways. Then you have the resulting silly lawsuits over the silly patents and other innovation-suppressing and time-wasting exercises. The corporate "Push to Patent" is remarkably similar to the academic "Push to Publish." 90% of the output of either is not worth reading. -- Sponsor the DES Analytic Crack Project http://www.cyberspace.org/~enoch/crakfaq.html