Cryptanalysis of Four-Round DES Based on Genetic Algorithm

In this paper, we present a new approach for cryptanalysis of four-round DES based on genetic algorithm. An efficient fitness measure is used to find some optimum keys with higher fitness values. Some valuable bits in these optimum keys which generate apparent deviation from the other observed bits will turn up. Then, these valuable bits can be applied to find other bits. The results indicate that genetic algorithm is successful at breaking the four-round DES cipher, but perhaps more significantly, this is a promising method applied to break other Feistel block cipher.