Certain investigations in Cryptanalysis of classical ciphers Using genetic algorithm

Abstract

The aim of the research presented in this thesis is to investigate the newlineuse of Genetic Algorithm GA in the cryptanalysis of some classical ciphers newlineThe objective of using GA is to reduce the search space many ways were newlineused to evaluate the fitness function in GA to select the best solutions of keys newlinethese keys are used in the decryption Algorithm to get the most letters of newlinecorrect plaintexts based on fitness value In the research certain investigations newlinehave been carried out on the cryptanalysis of four types of classical ciphers newlinethese ciphers are Vigenere Polyalphabetic Substitution Vernam and newlineTransposition Ciphers The Cryptanalysis of Vigenere cipher by applying Genetic newlinealgorithm is presented The frequency analysis and Score analysis which is newlinethe frequency of common bigrams and trigrams are used as essential factors newlinein fitness function Comparison study has been done between those factors newlineand shown that Score analysis has more ability to get more numbers of correct newlinekeys and plaintexts newline newline