Cryptanalysis of Vigenere cipher using Cuckoo Search

• Since the key space of Vigenere cryptosystem is very large, therefore, brute force does not help in the analysis of the cryptosystem in real time. Statistical techniques are also not helpful when the key size is not small.
• The aim of this work was to examine the feasibility of Cuckoo Search algorithm as a cryptanalysis tool of classical cryptosystems especially Vigenere cipher. We applied Genetic Algorithm, Particle Swarm Optimization and Cuckoo Search techniques for the analysis of Vigenere cipher. After doing lots of experiments we observed that GA and PSO techniques can recover the entire key of Vigenere Cipher correctly for keys of small lengths. However, Cuckoo Search can recover more than 90% of the key characters for keys of size up to 25 characters because GA and PSO get trapped in local minima while Cuckoo Search finds the global optimum solution following characteristics of Lévy flights.
• Experimental results show the superiority of CS in fast convergence and the accuracy in the cryptanalysis of Vigenere cipher over PSO and GA.

Evolutionary techniques such as Genetic Algorithm (GA), Particle Swarm Optimization (PSO) and Cuckoo Search (CS) are promising nature-inspired meta-heuristic optimization algorithms. Cuckoo Search combined with Lévy flights behavior and Markov chain random walk can search global optimal solution very quickly. The aim of this paper is to investigate the applicability of Cuckoo Search algorithm in cryptanalysis of Vigenere cipher. It is shown that optimal solutions obtained by CS are better than the best solutions obtained by GA or PSO for the analysis of the Vigenere cipher. The results show that a Cuckoo Search based attack is very effective on the Vigenere cryptosystem.