Heuristic search for non-linear cryptanalytic approximations

— In this work, we show that heuristic techniques (particularly Simulated Annealing) can be successfully applied in the search of good non-linear approximations of cryptographic primitives. We also provide some experimental results, including two excellent non-linear approximations for the output of the Salsa20 stream cipher with 2 and 4 rounds. From these two approximations, very efficient distinguishers for Salsa20 could easily be obtained, leading to a much more practical attack that any other published so far against this cipher.

• Type: Conference
• Year: 2007
• Where: CEC
• Authors: Juan M. Estévez-Tapiador, Julio César Hernández Castro, John A. Clark
• Keywords: Artificial Intelligence, CEC 2007, Cryptographic Primitives, Non-linear Approximations, Simulated Annealing