Fast and Lightweight Image Cryptosystem for IoMT Applications

This paper presents a fast and lightweight image encryption technique founded on a new concept of progressive and selective diffusion. We make use of modified chaotic systems like the sine-logistic system, sine-tangent system, and tent-logistic system to generate key blocks for diffusion. The encryption procedure comprises three stages: column diffusion, permutation, and row diffusion, which collectively contribute to the overall encryption mechanism. In the first stage, progressive and selective column substitution of the input image is conducted employing key-blocks D1 and D2, in a manner that each substituted column data is a function of previously diffused data. In the second stage, the column-substituted image goes through an adaptive permutation operation realized using an improved sin-logistic system. The last stage incorporates two distinct mappings based on key arrays and key blocks to ensure selective and progressive inter-row substitution/diffusion. The experimental results suggest that the proposed image system exhibits rapid performance as it reports an average encryption time of 0.03 seconds for an image of the size 256×256. Besides, the use of 1-D chaotic maps together with simple yet effective confusion and diffusion processes make it lightweight. Furthermore, it provides better security performance shown by various parameters like Information Entropy Analysis (IE), Correlation Coefficient analysis (CC), Histogram analysis, Differential Attacks Analysis (NPCR and UACI), key sensitivity assessment, and fidelity analysis. The suggested system has the capability to meet the cryptographic objectives as it reports average values of IE = 7.9974, CC =0.0035, NPCR =99.61%, UACI = 33.48%, and an enormously large key space compared to the state-of-art. The proposed technique offers enhanced data security, preserving patient privacy and preventing unauthorized access, while ensuring efficient encryption performance to assure the security and immediate transmission and storage of medical images. The better security performance together with computational efficiency and lightweight nature makes it an ideal candidate to be used in IoMT systems.