A Highly Secure Image Encryption Scheme using Compound Chaotic Maps

During the last two decades various chaotic image encryption algorithms have been proposed, but most of them encountered some defects like small key space, low speed, lack of robustness and weak security. This paper proposes a chaos-based image encryption scheme with a permutation–diffusion mechanism, where six skew tent maps and one sixdimensional Arnold map are utilized to generate one hybrid chaotic orbit applied to disorder the pixel positions in the permutation process, while four skew tent maps and one Arnold map are employed to yield two random gray value sequences to change the gray values by a two-way diffusion process. The major merits of the proposed image encryption scheme include a huge key space, desirable computation overhead, good statistical nature resisting statistical attack, differential attack and satisfying robustness against malicious attacks on cipher-images, such as cropping, noising, JPEG compression. Experimental results have been carried out with detailed analysis to show that the proposed scheme can be a potential candidate for practical image encryption.