Cryptanalysis of Transposition Cipher Using Hill Climbing and Simulated Annealing

Abstract

The need of an efficient encryption process has always been felt to hide the information from others during communication. In earlier days, the method of encryption was using paper and pen only and the term used for these encryption techniques was classical ciphers. Transposition cipher is one of the most popular classical ciphers. This is also called a permutation cipher where characters in the plain text are reshuffled to form a ciphertext according to a given permutation key. Various techniques apart from brute-force have been used to break transposition ciphers in ciphertext-only attack mode. These techniques mainly involve combinatorial optimization-based techniques such as hill climbing, simulated annealing, genetic algorithms and tabu search. In this paper, we have used hill climbing, simulated annealing and combination of these two for breaking transposition ciphers in ciphertext-only attack mode.