Genetic Algorithm & Tabu Search Attack on The Mono-Aiphanetic Substitution Cipher

Abstract

With the exponential growth of networked system and application such as Commerce, the demand for effective internet security is increasing. Cryptology is the science and study of systems for secret communication. It consists of two complementary fields of study: cryptography and cryptanalysis. In this paper, we propose a cryptanalysis method based on Genetic Algorithm and Tabu Search to break a Mono-Alphabetic Substitution Cipher. We will also compare and analyze the performance of these algorithms in automated attacks on a Mono-Alphabetic Substitution Cipher. The use of Tabu Search is a largely unexplored area in the field of Cryptanalysis. A generalized version of these algorithms can be used for attacking other cipher as well.

An automatic cryptanalysis of simple substitution ciphers using compression

“…For a cryptogram of 800 characters, 25 out of 27 key elements were recovered, and for a cryptogram of a length of 500, it was able to recover 23 keys (Clark, 1998). For a ciphertext of 200 characters, the amount of recovered keys was about 12 whereas with a 1000 character long ciphertext, about 24 keys was successfully recovered out of 27 (Garg & Sherry, 2005). Another genetic algorithm based solution (Grundlingh & Van Vuuren, 2003) was successfully implemented.…”

“…The essential concepts of substitution ciphers and transposition ciphers are still widely used nowadays in the Advanced Encryption Standard (AES) and the International Data Encryption Algorithm (IDEA). As long as the operations and the concepts of the classical cipher systems are the basic building blocks of more secure modern ciphers, then the classical ciphers are typically the first ciphers considered in the case of investigating and examining new attacks (Garg & Sherry, 2005).…”

“…With a very long ciphertext (5000 characters), the algorithm performed quite well, but it was less efficient with shorter ciphers. The use of genetic algorithms, simulated annealing and tabu search for the cryptanalysis was presented in (Clark, 1994;Garg & Sherry, 2005). Character unigram and digram frequencies were adopted as the basis of the fitness function in (Clark, 1994) and trigram as well in (Garg & Sherry, 2005).…”

“…The use of genetic algorithms, simulated annealing and tabu search for the cryptanalysis was presented in (Clark, 1994;Garg & Sherry, 2005). Character unigram and digram frequencies were adopted as the basis of the fitness function in (Clark, 1994) and trigram as well in (Garg & Sherry, 2005). For a cryptogram of 800 characters, 25 out of 27 key elements were recovered, and for a cryptogram of a length of 500, it was able to recover 23 keys (Clark, 1998).…”