A color image encryption algorithm based on hyperchaotic map and Rubik’s Cube scrambling

At present, many encryption algorithms for color images either decompose color images into three gray images and encrypt them, respectively, or combine R, G, B channels into a two-dimensional image matrix before encryption. These methods break the internal link between the three colors and reduce the efficiency of encryption. Here, to address these shortcomings, a new hyperchaotic system two-dimension Chebyshev–Sine coupling map (2D-CSCM) is proposed to improve the security of the encryption algorithm, and the dynamic behaviors of the system are analyzed by phase diagram, bifurcation diagram, Lyapunov exponent spectra information entropy and 0–1 test. We propose a Rubik's Cube scrambling method to scramble a three-dimensional bit-level matrix of the color image directly. Then the pixel values of the scrambled image matrix are diffused by two rounds of different operations based on chaotic sequences. The parameters and initial values of the chaotic system are derived from the secret key generated by the hash function SHA-512. Simulation results and security analysis demonstrate that the proposed algorithm has high efficiency and security to resist various common attacks.