A novel image cryptosystem for biomedical images and secured storage by randomized chaotic encryption scheme

Medical images transfer sensitive elements about diagnosis along with patient information across public networks between doctors and hospitals and patients. Secure storage and transmission methods must be implemented for image protection which addresses patient privacy. The proposed system introduces an elaborate image encryption method that uses chaotic and rotational systems for performing inter-block shuffling operations. A 2D sine map system with random behavior allows the algorithm to transform target images by performing scaling and rotational transformations and randomly reshuffling arrays. The chaotic system applies scaling and rotation operations as its first step before processing the medical image to reduce pixel dependencies. Permutation of the image produces an encrypted file through the S-box which applies a diffusion operation to the rearranged data. A chaotic system generates both unpredictability and sensitive initial condition reactions that produces a large key space that makes brute-force attacks less successful. Real-time operations are possible because the algorithm operates with fast data processing while using minimal resources. Evaluation results show that grayscale medical images perform better under security tests as the NPCR and UACI value reached above 98.53% and 34.33% throughout the testing phase.