Dynamical analysis of four-dimensional chaotic system and its application in image encryption

In this paper, a phase diagram of a four-dimensional chaotic system is established by introducing cosine function into Lorenz system. Then 0-1 test, complexity, and offset boosting, National Institute of Standards and Technology (NIST) test is conducted on the pseudo-random sequence generated by the system. Result shows that the system is suitable for image encryption. Combining with the proposed system, an image encryption algorithm based on hash and deoxyribonucleic acid (DNA) is designed. In this algorithm, through the plaintext hash value generated by the system initial values and the number of iterations to generate chaos sequence. By reordering the sequence of indexes to scrambling plaintext. In the diffusion module, we use XOR and cyclic left shift to get the final ciphertext. After simulation and security analysis, the algorithm has good encryption efficiency and security. It can resist most common attacks.