A Binomial Crossover Based Artificial Bee Colony Algorithm for Cryptanalysis of Polyalphabetic Cipher

Cryptography is one of the common approaches to secure private data and cryptanalysis involves breaking down a coded cipher text without having the key. Cryptanalysis by brute force cannot be accepted as an effective approach and hence, metaheuristic algorithms performing systematic search can be applied to derive the optimal key. In this study, our aim is to examine the overall suitability of Artificial Bee Colony algorithm in the cryptanalysis of polyalphabetic cipher. For this purpose, using a number of different key lengths in both English and Turkish languages, basic Artificial Bee Colony algorithm (ABC) is applied in the cryptanalysis of Vigenere cipher. In order to improve the ABC algorithm\u27s convergence speed, a modified binomial crossover based Artificial Bee Colony algorithm (BCABC) is proposed by introducing a binomial crossoverbased phase after employed bee phase for a precise search of global optimal solution. Different keys in various sizes, various cipher texts in both English and Turkish languages are used in the experiments. It is shown that optimal cryptanalysis keys produced by BCABC are notably competitive and better than those produced by basic ABC for Vigenere cipher analysis

Cryptanalysis of Polyalphabetic Cipher Using Differential Evolution Algorithm

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