Title: Cryptanalysis of classical ciphers with ant algorithms

Authors: Tahar Mekhaznia; Mohamed El Bachir Menai

Addresses: Department of Computer Science, University of Tébessa, Tébessa 12000, Algeria ' Department of Computer Science, College of Computer and Information Sciences, King Saud University, P.O. Box 51178, Riyadh 11543, Saudi Arabia

Abstract: Cryptanalysis of classical ciphers has been tackled using metaheuristic optimisation techniques, including ant colony optimisation (ACO) and particle swarm optimisation (PSO). Several variants of ACO algorithms have been developed to improve their search process, but their performance on the same problem may vary significantly according to the pheromone update rule they apply. In this paper, we introduce two versions of ACO algorithms for the cryptanalysis problem of classical ciphers, namely virtual ant system (VAS) and virtual MAX-MIN ant system (VMMAS). We investigate their performance on a large set of ciphertexts obtained by six different encryption methods, including Feistel, Vigenère, simple substitution, affine, carrè de Polybe, and transposition algorithms, and compare their performance against that of ant colony system (ACS) and elitist ant system (EAS). The experimental results demonstrate the overall superiority of VMMAS over the other ant algorithms. Moreover, comparison of VMMAS against a genetic algorithm (GA) establishes its advantage.

Keywords: cryptanalysis; classical ciphers; ant colony optimisation; ACO; genetic algorithms; cryptography; metaheuristics.

DOI: 10.1504/IJMHEUR.2014.065159

International Journal of Metaheuristics, 2014 Vol.3 No.3, pp.175 - 198

Available online: 15 Oct 2014 *

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