Attacking Transposition Cipher Using Improved Cuckoo Search

This paper presents an improved cuckoo search algorithm for automatic cryptanalysis of transposition ciphers. Transposition ciphers are a class of ciphers In which, a plaintext block is encrypted into a ciphertext block using a fixed permutation. The Improved cuckoo search(ICS) algorithm is done by adding a procedure to cuckoo search(CS) steps utilizing the similarities between population strings to find the global maxima of a cost function to find the secret key. The experiments show that for lower length of ciphertext there are cases that the secret key cannot be correctly found. This is the expected behavior of all cryptanalysis methods. Experimental results showed the ability of the proposed algorithm to attack 95% of encrypted messages with different key length using transposition cipher and gave better results compare with the traditional cuckoo algorithm on the amount of key recovery and time complexity.