A New Hyperchaotic Image Encryption Algorithm Based on Stochastic Signals

Image encryption is often used to protect private images during transmission on a public channel. A high dimensional chaotic map has a greater secret key space, better ergodicity and dynamic property than a low-dimensional chaotic system. A seven-dimensional (7D) hyperchaotic map is used to produce chaotic sequences. Given secret keys and SHA-512 function are employed to generate initial values for iteration. Many stochastic signals are injected into one of the variables during iteration to transfer trajectory and increase dynamic behavior of a chaotic system. Three matrices are constructed with generated chaotic sequences. Permutation is performed on the basis of a control matrix. It keeps the pixel far from its neighboring pixels. Cycle shift is executed during bit-level permutation. Characteristic values of scrambling image are calculated and temporary values are achieved successfully. Two dynamic values are also applied during the diffusion process. Experimental results display the effects of the proposed algorithm. Security analysis reveals that the proposed method has some special advantages.