Color image encryption scheme based on a novel 2D-CLCM chaotic system and RNA encoding

To improve the efficiency and security of image storage and transmission, a color image encryption scheme based on a chaotic map and RNA encoding is proposed in this study. Considering the limitations of some existing chaotic systems, such as discontinuities, uneven distributions, and fewer control parameters, a novel two-dimensional chaotic map coupled Logistic map and Cubic map named 2D-CLCM is proposed to participate in the image encryption process. The performance of 2D-CLCM is rigorously tested and verified through the bifurcation diagram, Lyapunov exponent, sample entropy, 0–1 test, and sensitivity analysis. The RNA encoding rules have the advantages of flexibility and diversity than DNA encoding. The color pixel composed of three channels is jointly encoded to 4 codons as each codon contains 6 bits. The intra-inter layers permutation is applied for the encoded RNA image using pseudo-random sequences generated with 2D-CLCM to perform pixel scrambling. Subsequently, the permutated RNA image and an RNA key matrix are mutually operated utilizing an operator matrix including addition, subtraction, XOR, and XNOR. Finally, the ciphertext image is obtained through decoding with rules different from the encoding process. This dual scrambling and diffusion process ensures robust security against various attacks. Experimental results demonstrate that the proposed method achieves excellent encryption performance in terms of histogram, correlation coefficient, information entropy, key space, NPCR, and UACI, highlighting its effectiveness for secure image encryption.