Making the most of two heuristics: breaking transposition ciphers with ants

M.D. Russell, J.A. Clark, S. Stepney
The 2003 Congress on Evolutionary Computation, 2003. CEC '03.  
Multiple anagramming is a general method for the cryptanalysis of transposition ciphers, and has a graph theoretic representation. Inspired by a partially mechanised approach used in World War II, we consider the possibility of a fully automated attack. Two heuristics based on measures of natural language are used -one to recognise plaintext, and another to guide construction of the secret key. This is shown to be unworkable for cryptograms of a certain difficulty due to random variation in the
more » ... constructive heuristic. A solver based on an ant colony optimisation (ACO) algorithm is then introduced, increasing the range of cryptograms that can be treated; the pheromone feedback provides a mechanism for the recognition heuristic to correct the noisy constructive heuristic.
doi:10.1109/cec.2003.1299423 fatcat:fcnuy47x7vf4bazen6c3drbgkm