Abstract: A new hyper chaotic image encryption algorithm using four directional diffusion on matrix is proposed to overcome the low efficiency of most hyper chaotic image encryption algorithm. Firstly, the original sequence generated by the hyper chaotic system is quantized and reconstructed to generate the key matrix with the same size as the plaintext image. Secondly, the initial vector required by the diffusion process is generated by the low-dimensional chaotic system. Finally, the vectorized operation is used to complete the global diffusion of pixel information from the top, bottom, left and right. The simulation results show that the algorithm can resist the attacks such as plaintext selection and differential analysis, and the time complexity of the algorithm is only O(M+N), which has both security performance and operation efficiency, and has a good effect  in the field of image real-time secure communication.

Key words: chaos theory, information security, image encryption, four directional diffusion, parallel encryption