Multi-layer permutation-substitution operations based novel lossless multiple color image encryption

This work develops a novel lossless multiple color image encryption based on multi-layer permutation-substitution operations. Initially, sixteen RGB images are converted into a single plain image using matrix theory. The single plain image is then segmented into red (R), green (G) and blue (B) color channels. Each channel is used as an input image for the further process. The first layer of permutation-substitution is obtained using random matrix affine cipher (RMAC). Both row and column permutation-substitution processes are simultaneously performed in this layer. The second layer of permutation-substitution is acquired using generalized three-dimensional (3D) Arnold transform. Lastly, the third layer of permutation-substitution is achieved using non-linear 3D chaotic map. In the proposed technique, SHA-256 hash function is utilized to generate the secret keys. This makes the system extremely sensitive to the plain image and improves its robustness against plaintext attacks. In addition, the multi-layer permutation-substitution operations make our system more secure and stronger with exorbitant huge key space, high sensitivity, randomness and uncertainty between the pixels. Also, the proposed system deals with multiple images at a time which supports high security, efficiency and capacity space in transmitting and storing the data. Simulation analysis validates the effectiveness of our proposed work. Moreover, the proposed technique is empirically assessed via security and statistical evaluation metrics. The experimental findings from the evaluation metrics and comparison analysis validate that our proposed technique is robust and secure enough for real-world applications.