> >And RC5 (Why does isakmp-oakley-03 use RC5-R12-B64 instead of >RC5-R16-B128.)? Actually it has been modified to RC5-R16-B64. The 64 bit block size was chosen since all of the public source code available was using 64 bits. RC5 also states that the block size should be twice the size of the CPU word ( 2 * 32 = 64 bits ) The ESP RC5 draft uses a very similar approach. >