Chaotic image encryption algorithm using wave-line permutation and block diffusion

An efficient and secure image encryption algorithm is proposed in this manuscript using SHA-3 hash function together with double two-dimensional Arnold chaotic maps. Classical encryption architecture, i.e., permutation plus diffusion, is employed in our scheme. To avoid time consumption of sorting operation for pixel position index in permutation stage, a novel wave-line-based confusion is suggested with four random directions of shuffling. The keystream generated by Arnold map is used for vertical and horizontal circular confusions, respectively, in which the initial conditions are updated by the SHA-3 hash values of chaotic matrix and a new vector produced from the plain-image. As a result, the proposed scheme can resist the known-plaintext attack compared with some existing encryption methods. Furthermore, in diffusion stage, a blocking method is designed with the outputs of hash values in the former block permuted image which are used to update again the initial conditions for Arnold map. The current block will influence the next block during the iterations, of which can resist well the chosen-plaintext attack. Numerical results show that the proposed encryption algorithm can have higher security and faster implementation for digital image communication.