Evaluating the permutation and diffusion operations used in image encryption based on chaotic maps

In recent years, there has been a growing interest in image encryption based on chaotic maps. In this paper, we evaluate the permutation and diffusion operations used in image encryption based on chaotic maps. Firstly, we research the permutation operation and diffusion operation, respectively. We use common analytical criterion to measure the effect of encryption operation. Then we employ the same method to evaluate the combinational operation, which is widely used in chaotic image encryption. Finally, we reverse the order of combinational operation and reevaluate the effect of encryption operation. By the evaluating results, researchers can choose the best operation to encrypt image, and improve the effect and security of algorithm based on chaotic maps.