USEs OF GA, PSO and MPSO TO BREAK TRANSPOSITION CIPHER SYSTEM: comparative study
Keywords:ciphertext, cryptanalysis, Transposition Cipher, Genetic Algorithm, Particle Swarm Optimization Algorithm.
GA is an adjustable search method that has the ability for search in
smart way to find the best solution and trying to reduce the time that required
for obtaining the optimal solution. Particle Swarm Optimization (PSO)
algorithm emulate the behavior of a swarm of fish and bird flocks. It's a
heuristic global optimization method which can be implemented and
applying to solve various optimization problems. The most attractive of using
PSO is that it has a fast convergence than the other global optimization
methods. Modify PSO (MPSO) is a relatively new approach to attacks
transposition cipher which it depends on using multi swarms rather than
single swarm and allowing the particles in all swarms to exchange
information between them in order to obtains the best solution from all
This research focuses on use GA, PSO and MPSO to cryptanalyze
transposition cipher based on a new tools to determine the fitness function by
calculating the Diagram(DG), Trigram(TG) and Quadgram (QG) frequency
of letters. It is shown that such algorithms can be used to reduce the number
of trails which are needed to determined the initial states of the attacked
systems using ciphertext only attack.
Experimental results show the successful applications of GA, PSO and
MPSO in cryptanalysis of transposition cipher system. Also, the experimental
results indicate that the MPSO is more powerful than the other techniques in
cryptanalysis transposition depending on the accuracy of results.