ROMPIMIENTO DEL ALGORITMO DES UTILIZANDO FUERZA BRUTA Y PROGRAMACIÓN PARALELA

Abstract

To hide information from people outside the enterprise has been always important. When the computers showed up, it was necessary to create new and better protection methodologies, having as a result the creation of some encryption algorithms as the one known as DES (Data Encryption Standard). DES is an algorithm, consisting on 16 rounds. In each one, there are substitution, permutation and X-or operations with the 64 bits of the original message and the chosen key for the encryption. DES has been attacked several times, among the most known attacks, we have the Differential Cryptanalysis, the Lineal Cryptanalysis and diverse brute force attacks. The brute force attacks done to DES, usually require a specific purpose computer, which has the objective of trying all the possible keys; they can also been done with distributed computing. In this paper, a brute force attack to DES by software is proposed, using parallel computing with the multiple cores processors. In order to carry out the attack, it was necessary to create an efficient sequential program, that later was parallelized using OpenMP. OpenMP helps to add concurrency to the programs written even in C or Fortran. With the parallel program is possible to try more than one key at the same time (the number of keys depends on the quantity of cores in the processor). After trying the algorithm, it was possible to realize that the speed up in the parallel program compared with the sequential is 3.7 on average. Even though the decreasing in the execution time, at attacking with four processors the processing time is really high (more than a hundred thousand years) at trying the keys universe, that’s why we can´t attack DES with just four processors.