3D variable-structure chaotic system and its application in color image encryption with new Rubik's Cube-like permutation

Nowadays, images have an increasingly deep impact on human life, so it is essential to encrypt images. Among various image encryption methods, chaotic encryption is particularly prominent due to the unpredictability and initial state sensitivity of chaos. The security of chaos-based cryptosystems depends largely on the performance of the adopted chaotic systems. This paper proposes a three-dimensional variable-structure chaotic system (3DVSCS) whose structure is time-varying. The distinguished dynamical characteristics of 3DVSCS are verified by various metrics, such as lyapunov exponent, approximate entropy, etc. Taking full advantage of the chaotic sequences generated by the 3DVSCS, a novel cryptosystem (3DVSCS-IES) with the confusion-diffusion architecture is presented. To further enhance security, a novel Rubik's Cube-like permutation method is designed to severely scramble adjacent pixels, and an iterative diffusion algorithm is employed to completely infect the entire cipher image with a slight change in the plaintext image. The security analyses show that the proposed image encryption algorithm owns better security performance than some typical state-of-art methods.