Differential Cryptanalysis of Symmetric Block Ciphers Using Memetic Algorithms

Abstract

The paper presents a new differential cryptanalysis attack based on memetic algorithms. A prepared attack is directed against the ciphertext generated by one of the most popular ciphers named Data Encryption Standard (DES) reduced to six rounds of an encryption algorithm. The main purpose of the proposed MASA attack is to indicate the last encryption subkey, which allows the cryptanalyst to find 48 from 56 bits of decrypting key. With a simple comprehensive search, it’s possible to get the remaining 8 bits. The memetic attack is based on the simulated annealing algorithm, used to improve the local search process, to achieve the best possible solution. The described algorithm will be compared with a genetic algorithm attack, named NGA, based on an additional heuristic operator.