Mod n cryptanalysis: Difference between revisions

Revision as of 17:52, 23 December 2008

Revision as of 13:20, 13 April 2009

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: <math>X \lll 1 \equiv 2X\pmod 3.</math>

Thus left rotation by a single bit has a simple description modulo 3. Analysis of other operations (data dependent rotation and modular addition) reveals similar, notable biases. Although there are some theoretical problems analysing the operations in combination, the bias can be detected experimentally for the entire cipher. In (Kelsey et. al., 1999), experiments were conducted up to seven rounds, and based on this they conjecture that as many as nineteen or twenty rounds of RC5P can be distinguished from random using this attack. There is also a corresponding method for recovering the secret [[key (cryptography)|key]].

Against M6 there are attacks mod 5 and mod 257 that are even more effective.