A novel double image encryption algorithm based on coupled chaotic system

This paper constructs a two-dimensional Logistic-Sine-Henon map (2D-LSHM) for image encryption. By comparing with some existing chaotic systems, the 2D-LSHM has better chaotic performance and is more suitable for image encryption scenarios. Using the 2D-LSHM, we propose a double image adaptive encryption algorithm consisting of bit-level combinatorial permutation and four-directional adaptive diffusion called LSHM-DIAEA. Differently from traditional image encryption algorithms, the proposed LSHM-DIAEA can encrypt a color image and a grayscale image at the same time so that the information from each other can be fused and affected by each other, which makes the encryption process more secure and efficient. In addition, to enhance plaintext sensitivity, we introduce the secure hash algorithm-512 (SHA-512) and the Histogram of Oriented Gradient (HOG) feature extraction algorithm into the LSHM-DIAEA. Simulation and security analysis results illustrate that the LSHM-DIAEA provides a high security level to resist various cryptanalytic attacks and a high execution efficiency.