ABSTRACT

Vigenere cipher is a polyalphabetic substitution cipher with a very large key space. In this paper we have investigated the use of PSO for the cryptanalysis of vigenere cipher and proposed PSO with Markov chain random walk in which some of the worst particles are replaced with new better random particles to enhance the efficiency of PSO algorithm. Based on our experimental results, it is shown that the proposed algorithm is more effective than PSO for the analysis of Vigenere cipher.