Secure Image Encryption Algorithm based on Two-Level Diffusion and Hybrid Chaotic Maps

Security is an essential aspect of a communications network. With the availability of the internet, a lot of private data is transferred daily, requiring robust protection of these data. In this paper, an image encryption algorithm is proposed based on two-level diffusion and two hybrid chaotic maps. The two-level diffusion consists of bit-level decomposition and shifting of the pixel. Firstly, the two hybrid chaotic maps, namely, the sine-cubic hybrid maps (SCHM) and the sine-logistic hybrid map (SLHM), are developed from the conventional 1D chaotic maps. Secondly, two keys are generated from the hybrid maps. The sine-cubic hybrid map generates the first key, and the sine-logistic hybrid map generates the second key. The first key is used for shifting the decomposed image. A simple logic is used to shift the decomposed image clockwise or anticlockwise. Followed by shifting the bitwise-XOR operation is done between the second key and the diffused image. Finally, different attack and security analyses are performed to measure the robustness of the encryption techniques, such as encryption correlation coefficient, histogram analysis, entropy, PSNR, MSE, differential, and noise attack analysis are performed. The results reveal that the proposed image encryption algorithm is able to resist several attacks.