Generic attacks with standard deviation analysis on a-feistel schemes

Abstract

A usual way to construct block ciphers is to apply several rounds of a given structure. Many kinds of attacks are mounted against block ciphers. Among them, differential and linear attacks are widely used. Vaudenay showed that ciphers achieving perfect pairwise decorrelation are secure against linear and differential attacks. It is possible to obtain such schemes by introducing at least one random affine permutation as a round function in the design of the scheme. In this paper, we study attacks on schemes based on classical Feistel schemes where we introduce one or two affine permutations. Since these schemes resist against linear and differential attacks, we will study attacks based on specific equations on 4-tuples of plaintext/ciphertext messages. We show that these schemes are stronger than classical Feistel schemes.