Chaos-based image encryption with total shuffling and bidirectional diffusion

This paper proposes a chaos-based image encryption method with permutation–diffusion architecture, in which a spatiotemporal chaotic system modeled by coupled map lattices is used to generate random sequences. In the permutation step, the permutation is generated of the same size as the plain image, which shuffles the positions of image pixels totally. In order to effectively generate this large permutation, we present a fast method to construct permutation by combining several small permutations, where small permutations are directly generated by a chaotic system. In the diffusion step, bidirectional diffusion is used to diffuse each pixel to all other pixels of the image. A key stream buffer is utilized to cache the random numbers generated by the chaotic system, and each pixel is ciphered by a random number chosen from the key stream buffer according to its previous pixel. The experimental results and analysis by using several security measures show that the proposed image encryption scheme has high security and efficiency.