Cryptanalysis of Polyalphabetic Cipher Using Differential Evolution Algorithm

Abstract

Today it is necessary to keep information secure and cryptography is the most common technique for data security. The Vigenere cipher, one of the polyalphabetic encryption algorithms, has been used in the history by substitution of the plaintext letters with other alphabet letters using a secret keyword and a systematic table. In order to make the ciphertext readable with a keyless procedure, the cryptanalysis technique is used. However, extracting all possible permutations of the letters is exhaustive or frequency analysis is ineffective to extract the letters from the cipher. Therefore, this study aims to propose an efficient polyalphabetic Vigenere cipher cryptanalysis using Differential Evolution algorithm on English and Turkish texts at different lengths. The efficiency of the Differential Evolution algorithm is compared to those of Genetic Algorithm and Particle Swarm Optimization algorithms in terms of the number of key letters recovered correctly. The results show that Vigenere cipher analysis using Differential Evolution algorithm is more effective in polyalphabetic cryptanalysis.

Keywords

• cryptanalysis
• differential evolution
• genetic algorithm
• particle swarm optimization
• vigenere cipher