¹Graduate School, Air Force Engineering University, Xi’an, Shanxi, China.
²Air and Missile Defense College, Air Force Engineering University, Xi’an, Shanxi, China.

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Abstract—According that the current color image encryption algorithms of “scrambling – diffusion” mode have many problems, such as the small key space, the tedious encryption process, the security vulnerability and so on, this paper proposes a new color image encryption algorithm based on the hyperchaotic system, which adopts “transforming - scrambling - diffusion” model. Before scrambling, in accordance with the image itself attributes, the number of iterations is calculated, all the pixel values of color image gray code iterative transformation, then the chaotic sequence generated from the four-dimensional hyper-chaotic system and pixel matrix converted to gray code are transformed to one dimensional matrixes .The former is sorted and the later change correspondingly to complete the image pixel matrix of the whole domain scrambling. And then, bit operation is executed to complete image diffusion. the ciphertext is obtained by matrix transformation. The key sensitivity histogram information entropy correlation and other evaluation indexes are calculated and analyzed through the simulation experiment, and compared with other algorithms, proving that the encryption algorithm has strong anti-attack ability.

Index Terms—Hyper-chaotic system, color image encryption, gray code key space.

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Cite: Fangzheng Zhao, Chenghai Li, Chen Liu, "A Hyper-Chaotic Color Image Encryption Algorithm and Security Analysis," Journal of Computers vol. 14, no. 7, pp. 496-506, 2019.