Modification of Some Solution Techniques of Combinatorial Optimization Problems to Analyze the Transposition Cipher

In this paper we attempt to use a new direction in cryptanalysis of classical crypto systems. The new direction represented by considering some of classical crypto systems, like transposition cipher problem (TCP), as a combinatorial optimization problem (COP), then using the known solving methods of COP, with some modification, to cryptanalysis the TCP. In this work we investigate to use Branch and Bound (BAB) and one of swarm algorithms as a local search method. The main aim of the research presented in this paper is to investigate the use of some optimization methods in the fields of cryptanalysis and cryptographic function generation. These techniques were found to provide a successful method of automated cryptanalysis of a variety of the classical ciphers. Keywords: cryptography, cryptanalysis, Classical Ciphers, Transposition Cipher, Branch and Bound, Swarm Intelligence, Bees Algorithm