Generic Attacks on Classical Feistel Ciphers with Internal Permutations

In this chapter, generic attacks on Feistel networks with internal permutations, instead of Feistel networks with internal functions as designed originally are studied. As always in generic attacks, the internal permutations are supposed to be random. However, as we will see, Feistel networks with internal permutations do not always behave like the original Feistel networks with roundfunctions.