Cryptanalysis of Nonlinear Stream Cipher Cryptosystem based on Improved Particle Swarm Optimization

Stream cipher is one of the hard electronic cipher systems because of high security and difficulty in breaking it. In this paper the proposed cryptanalysis system based on a Particle Swarm Optimization (PSO) with suggestions for improving the achievement of PSO, by using Simulated Annealing (SA) that is the first part of this paper. The second part represented by a comparison study for the cryptanalysis results obtained by the Improved PSO (IPSO) with classical PSO and Genetic Algorithm (GA).The cryptanalysis process include finding the initial state of the attacked stream cipher cryptosystem using ciphertext only attack.