Advancing cryptographic Security with an S-box for robust data encryption in SM4 Algorithm

Ensuring robust data encryption is crucial for secure communication, particularly in power metering data transmission. This study presents a novel hybrid algorithm for optimizing the Substitution Box (S-box) in the SM4 encryption method, addressing critical cryptographic security challenges. The proposed S-box design integrates simulated annealing and evolutionary algorithms to enhance non-linearity, reduce differential and linear probabilities, and improve resistance to cryptanalytic attacks. A comparative analysis against standard S-box designs demonstrates superior security performance, including enhanced avalanche and diffusion properties. Additionally, the scalability and hardware implementation feasibility of the proposed approach are evaluated, highlighting its potential for real-world cryptographic applications. The security analysis confirms the robustness of the redesigned Sbox against differential and linear cryptanalysis, ensuring improved encryption strength. This research contributes a practical, high-security S-box solution for modern cryptographic frameworks.Keywords—Network security, chaos, random numbers, S-Box, Rook, chess, SM4 algorithm.