An efficient nested chaotic image encryption algorithm based on DNA sequence

In this paper, an efficient scheme for image encryption based on the nested chaotic map and deoxyribonucleic acid (DNA) is introduced. In order to generate the initial condition values of the nested chaotic system, the Secure Hash Algorithm SHA-256 is used. The algorithm consists of two main layers: confusion and diffusion. In the first layer, the nested chaotic map is employed to create the scrambled image. The scrambled image is obtained through the ascending sorting of the first component of the nested chaotic index sequence. To ensure higher sensitivity, higher complexity and higher security, DNA sequence and DNA operator are employed additionally with the nested chaotic map and hash algorithm to modify the pixel values. The important advantages of our algorithm are the improvement of Number of Pixel Change Rate (NPCR), Unified Average Changing Intensity (UACI) and entropy, which improve resistivity against several attacks. Experimental results and relevant security analysis demonstrated that our proposed encryption scheme has the highest security level because it is more complicated, and it has a sufficiently large key space. The proposed method is compared to other recent image encryption schemes using different security analysis factors, including NPCR, UACI, correlation coefficients (CCs), encryption quality (EQ) and entropy. It is also resistant to noise (Salt and Pepper, Gaussian and speckle) and data loss attacks. The illustrated results demonstrated that the proposed image encryption scheme is efficient, and can be adopted for image encryption and transmission.