A Comparison between Memetic algorithm and Genetic algorithm for the cryptanalysis of Simplified Data Encryption Standard algorithm

Genetic algorithms are a population-based Meta heuristics. They have been successfully applied to many optimization problems. However, premature convergence is an inherent characteristic of such classical genetic algorithms that makes them incapable of searching numerous solutions of the problem domain. A memetic algorithm is an extension of the traditional genetic algorithm. It uses a local search technique to reduce the likelihood of the premature convergence. The cryptanalysis of simplified data encryption standard can be formulated as NP-Hard combinatorial problem. In this paper, a comparison between memetic algorithm and genetic algorithm were made in order to investigate the performance for the cryptanalysis on simplified data encryption standard problems(SDES). The methods were tested and various experimental results show that memetic algorithm performs better than the genetic algorithms for such type of NP-Hard combinatorial problem. This paper represents our first effort toward efficient memetic algorithm for the cryptanalysis of SDES.Comment: 9Page

Cryptanalysis of Homophonic Substitution-Transposition Cipher

Homophonic substitution ciphers employ a one-to-many key to encrypt plaintext. This is in contrast to a simple substitution cipher where a one-to-one mapping is used. The advantage of a homophonic substitution cipher is that it makes frequency analysis more difficult, due to a more even distribution of plaintext statistics. Classic transposition ciphers apply diffusion to the ciphertext by swapping the order of letters. Combined transposition-substitution ciphers can be more challenging to cryptanalyze than either cipher type separately. In this research, we propose a technique to break a combined simple substitution- column transposition cipher. We also consider the related problem of breaking a combination homophonic substitution-column transposition cipher. These attacks extend previous work on substitution ciphers. We thoroughly analyze our attacks and we apply the homophonic substitution-columnar transposition attack to the unsolved Zodiac-340 cipher

Cryptanalysis of Simplified-AES using Particle Swarm Optimisation

Particle swarm optimisation (PSO) based cryptanalysis has gained much attention due to its fast convergence rate. This paper proposes a PSO-based cryptanalysis scheme for breaking the key employed in simplified-advance encryption standard (S-AES). The cost function is derived using letter frequency analysis. The novelty in our approach is to apply ciphertext-only attack for an S-AES encryption system, where we obtained the key in a minimum search space compared to the Brute-Force attack. Experimental results prove that PSO can be used as an effective tool to attack the key used in S-AES.Defence Science Journal, 2012, 62(2), pp.117-121, DOI:http://dx.doi.org/10.14429/dsj.62.77

A STUDY AND IMPLEMENTATION OF ENCRYPTION, WITH EMPHASIS ON CHAOTIC MAPS

The security of data transmitted over public communication networks and valuable data storage have necessitated the need for very secure cryptography. Applications like video teleconferencing, cable TV broadcast, etc use encryption extensively. Hence researches for better ways of protecting data are still underway. And this project was aimed at finding secure cipher by implementing Logistic Map Cipher for plaintext encryption and decryption. The research was based on both symmetric ciphers and asymmetric ciphers. The symmetric cryptosystem was chosenand finally implemented. In trying to implement logistic map, Chaotic Maps were briefly analyzed and other types of encryption were investigated in order to understand intensive and extensive applications of cryptography. The three main parts of focus are keys' generator, the encryption and decryption parts, which are the main steps before cryptanalysis can be carried out. In encryption, the individual success of different parts will guarantee a complete cipher

Implementation of cryptographic algorithms and protocols

The purpose of the project is to provide a practical survey of both the principles and practice of cryptography. Cryptography has become an essential tool in transmission of information. Cryptography is the central part of several fields: information security and related issues, particularly, authentication, and access control. Cryptography encompasses a large number of algorithms which are used in building secure applications

Genetic algorithms in cryptography

Genetic algorithms (GAs) are a class of optimization algorithms. GAs attempt to solve problems through modeling a simplified version of genetic processes. There are many problems for which a GA approach is useful. It is, however, undetermined if cryptanalysis is such a problem. Therefore, this work explores the use of GAs in cryptography. Both traditional cryptanalysis and GA-based methods are implemented in software. The results are then compared using the metrics of elapsed time and percentage of successful decryptions. A determination is made for each cipher under consideration as to the validity of the GA-based approaches found in the literature. In general, these GA-based approaches are typical of the field. Of the genetic algorithm attacks found in the literature, totaling twelve, seven were re-implemented. Of these seven, only three achieved any success. The successful attacks were those on the transposition and permutation ciphers by Matthews [20], Clark [4], and Griindlingh and Van Vuuren [13], respectively. These attacks were further investigated in an attempt to improve or extend their success. Unfortunately, this attempt was unsuccessful, as was the attempt to apply the Clark [4] attack to the monoalphabetic substitution cipher and achieve the same or indeed any level of success. Overall, the standard fitness equation genetic algorithm approach, and the scoreboard variant thereof, are not worth the extra effort involved. Traditional cryptanalysis methods are more successful, and easier to implement. While a traditional method takes more time, a faster unsuccessful attack is worthless. The failure of the genetic algorithm approach indicates that supplementary research into traditional cryptanalysis methods may be more useful and valuable than additional modification of GA-based approaches

Data Encryption and Decryption by Using Hill Cipher Algorithm

The core of Hill-cipher is matrix manipulations. It is a multi-letter cipher, for decryption the inverse of matrix requires and inverse of the matrix doesn’t always exist. Then if the matrix is not invertible then encrypted text cannot be decrypted. However, a drawback of this algorithm is overcome by use of self-repetitive matrix. This matrix if multiplied with itself for a given mod value (i.e. mod value of the matrix is taken after every multiplication) will eventually result in an identity matrix after N multiplications. So, after N+ 1 multiplication the matrix will repeat itself. Hence, it derives its name i.e. self-repetitive matrix. It should be non-singular square matrix. Key words: Hill Cipher Algorithm, Self-Repetitive Matrix and Inverse Matrix DOI: 10.7176/NCS/11-02 Publication date:July 31st 202