ATTACK TO BLOCK CIPHERS BY CLASS ELIMINATION USING THE GENETIC ALGORITHM

Abstract

In recent years, the use of Genetic Algorithms in symmetric cryptography has increased, in particular in the cryptanalysis of block ciphers. However, it is still necessary to continue the study and search for better characteristics. In this sense, two methodologies of partition of the key space that connect the Genetic Algorithms with the attack to block ciphers have been proposed in previous work. In this paper, we propose a methodology for attacking, where it is possible to discard some classes, reducing the total number that would be necessary to go over. In connection with this approach, we obtain necessary conditions and formulas to estimate the parameters’s value that determines a balance between the number of classes into which the key space is divided and the number of elements of each one of them, solving the problem of optimal selection of the parameters.