Mod n Cryptanalysis, with Applications against RC5P and M6

J. Kelsey, B. Schneier, and D. Wagner

Fast Software Encryption, Sixth International Workshop Proceedings (March 1999), Springer-Verlag, 1999, pp. 139-155.

ABSTRACT: We introduce "mod n cryptanalysis," a form of partitioning attack that is effective against ciphers which rely on modular addition and bit rotations for their security. We demonstrate this attack with a mod 3 attack against RC5P, an RC5 variant that uses addition instead of XOR. We also show mod 5 and mod 257 attacks against M6, a cipher proposed in the FireWire standard. We expect mod n cryptanalysis to be applicable to many other ciphers, and that the general attack is extensible to other values of n.

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