Adaptation of a genetic operator and a dynamic S-box for chaotic encryption of medical and color images

In this article, we will propose a new method for encrypting of arbitrary sizes and formats. Based on chaos, this new technique starts with the construction of an S-box of size 16×16, improved by a dynamic behavior and attached to new substitution and diffusion functions to overcome the problem of differential and statistical attacks. A passage in hexadecimal notation is carried out on the values of the pixels of the original image, followed by a subdivision of the vector obtained into sub-blocks of size 1×6, for a future submission to two rounds of genetic mutation adapted to ciphers of color images and controlled by chaotic vectors. The outgoing vector will be subjected to substitutions accompanied by an improved operating mode (CBC), to increase the impact of the avalanche effect and protect the system against any known attack. Tests carried out on many images of different sizes and formats have proven the robustness of our approach.