Automated Cryptanalysis of Transposition Ciphers

In this paper we use simulated annealing for automatic cryptanalysis of transposition ciphers. Transposition ciphers are a class of ciphers that in conjunction with substitution ciphers form the basis of all modern symmetric algorithms. In transposition ciphers, a plaintext block is encrypted into a ciphertext block using a fixed permutation. We formulate cryptanalysis of the transposition cipher as a combinatorial optimization problem, and use simulated annealing to find the global minimum of a cost function which is a distance measure between a possible decipherment of the given ciphertext and a sample of plaintext language