Color Image Encryption Based on Five-Dimensional Continuous Hyperchaotic System and Optimized Arnold Algorithm

This paper introduces a novel color image encryption algorithm based on a five-dimensional continuous memristor hyperchaotic system (5D-MHS), combined with a two-dimensional Salomon map and an optimized Arnold transform. Firstly, convert the test image to a 2D pixel matrix then processed in blocks, and each block of the pixel matrix is permuted with chaotic sequences generated by 5D-MHS and 2D Salomon map. Then, the permuted image is permuted for three rounds with the optimized Arnold algorithm. Finally, one of the chaotic sequences generated by 5D-MHS is employed to diffuse the permuted image to obtain the final ciphertext image. In this paper, several pseudo-random sequences are generated and mixed in the permutation stage to achieve higher security. The algorithm achieves a key space of 2⁴⁷², the information entropy of the ciphertext image for the color image is 7.9998, number of pixels change rate (NPCR) and unified average changing intensity (UACI) reached 99.6131 % and 33.4361 %, respectively, and the correlation between pixels is close to O. The simulation results show that the encryption algorithm is efficient and the key system is secure.