Dr. Ali Mohammad Haroun Al-Ghonmein

With the growing reliance on cloud-based healthcare solutions, safeguardingthe confidentiality and integrity of sensitive medical imaging data—governedby standards such as DICOM (Digital Imaging and Communications in Medi-cine) has become paramount. This study proposes a novel, robust, andcomputationally effective image encryption protocol tailored for protectingmedical images during both their transmission and storage within cloud hos-pital infrastructures. The scheme overcomes the deficiencies of conventionalencryption techniques and simple chaotic maps by implementing a hybridmulti-chaotic system. This system amalgamates four unique chaotic maps:the Logistic map, the Tinkerbell map, a bespoke high-degree polynomialmap, and the Bogdanov map. The encryption process is structured on apermutation-diffusion paradigm. Specifically, the Bogdanov map is employedto produce a chaotic permutation matrix that scrambles pixel locations toachieve strong diffusion properties. Following this, a composite keystreamderived from the combination of the Logistic, Tinkerbell, and custom poly-nomial maps performs pixel value substitution through a bitwise XOR oper-ation. This layered methodology delivers robust defense against statistical,differential, and brute-force attacks. The scheme supports both grayscale andcolor medical images, addressing the diverse needs of contemporary diagnos-tic imaging. A detailed security evaluation is conducted, encompassing keyspace analysis, NIST SP 800-22 randomness tests, entropy assessment, cor-relation analysis, and differential attack resistance metrics (NPCR/UACI).Experimental findings confirm that the proposed encryption achieves a keyspace exceeding 2747, entropy values close to the ideal 8.0, correlation coef-ficients approaching zero, and NPCR/UACI statistics within optimal theo-retical bounds. Moreover, the algorithm exhibits computational efficiencyconducive to real-time secure management of medical images, fully align-ing with HIPAA (Health Insurance Portability and Accountability Act) andGDPR (General Data Protection Regulation) compliance requirements.