Cryptanalysis of image encryption algorithm based on pixel shuffling and chaotic S-box transformation

Abstract

Recently Hussain et al. proposed an image encryption algorithm which has three independent phases: (1) total pixel shuffling performed, in spatial domain, with permutation sequences extracted from chaotic skew tent map, (2) diffusion carried out using random codes generated from same chaotic map, and (3) extra confusion induced with substitution-box transformation. Though, the encryption algorithm achieves optimal scores of NPCR/UACI and exhibits great encryption strength. But, a careful analysis unveils its inherent security flaws, leaving it vulnerable to cryptographic attack. In this paper, we analyze its security weaknesses and proposed a chosen plaintext-attack with inverse S-box to break the algorithm completely. It is shown that the plainimage can be recovered successfully without knowing the secret key. The computer simulation of attack highlights the ineptness of Hussain et al. algorithm and shows that it is not commendable to deploy it for practical encryption of digital images.