A New Image Encryption Algorithm Based On Chaos And Cellular Automata

With the rapid development of the Internet, multimedia and other related technologies, more and more information can be transferred easily and quickly on the network. However, because the network is open to all users, and it will cause some information security threats. As image is an important form of information, its security has attracted wide attention. One of the most important means that solve the problem of image information security is image encryption.Since chaos has some good characteristics, such as well pseudorandom quality, high sensitivity to the parameters and ergodicity, so it often used in the field of image encryption; cellular automata has a simple, structured and highly parallel structure and also has complex nonlinear dynamics, which is widely used in the field of cryptography.This article first introduces some basic knowledge of cryptography and image encryption, then introduces the basic theory of chaos and cellular automata, on this basis, proposes two image encryption algorithms based on chaos and cellular automata. The first one is the image encryption algorithm based on coupled chaos and coupled cellular automatas, in which it uses the idea of coupling to strengthen the encryption performance of the encryption system; and then uses two-dimensional cellular automata to achieve parallelism in the process of encryption; finally uses chaos to finish image scrambling, thus reach the goal of the whole image encryption process. The second one is the image encryption algorithm based on constructed chaos and cellular automata, this part firstly constructs a discrete chaos on the basis of some relevant chaotic theories to finish image encryption; and then take advantage of "十" shaped cellular automata to encrypt image in CBC mode, combined with partial image bit matrix encryption; finally uses chaos to scramble image by group, thus finish image encryption.Both those two algorithms adopt the manner of encrypting image for three times. Simulation results show that those two algorithms have a good property of diffusion and confusion, they also have a large key space, are highly sensitive to the key, moreover, they can effectively resist brute-force attacks, statistical analysis attacks, differential analysis attacks and information entropy analysis attacks.