An image encryption algorithm for visually meaningful ciphertext based on adaptive compressed, 2D-IICM hyperchaos and histogram cyclic shift

Shiwei Jing, Jianjun Li

Abstract: In this paper, a new meaningful ciphertext compression encryption scheme is proposed. Firstly, this paper proposes an adaptive sparsification compressed sensing (CS) to get a better reconstructed image by adaptively assigning a more appropriate sparsity threshold to each image. Secondly, considering the noise-like distribution of the measured values, this paper proposes a histogram-shifted least significant bit (LSB) Xor embedding method to reduce the variation of the cover image. The algorithm can also adaptively find the optimal histogram shift parameters based on the distribution of measured values to optimize the ciphertext quality. The peak signal-to-noise ratio of the ciphertext reaches more than 48dB, which is much higher than the existing optimal algorithm. Then, we also proposed a new two-dimensional infinite collapse hyperchaos (2D-IICM), whose two Lyapunov exponents (LE) both reach more than 4 and are in a hyperchaotic state. The sample entropy and information entropy of the sequence can also reach more than 2 and 7.9 respectively, which is 0.1 and 0.3 points higher than other chaos. Good chaos properties provide higher security to the algorithm. This paper uses SHA256 of plaintext to generate a dynamic key, so that the whole encryption system achieves the encryption effect of one-image and one-key, making the entire system highly resistant to attacks. Codes are available at https://github.com/jsw1995/ICMCE