Advancing Key Expansion Techniques: Integrating Cross-Coupled Map Lattice and Dynamic S- Box for Superior Cryptographic Security

Abstract

This research investigates the security loopholes inherent in the traditional Advanced Encryption Standard (AES) key expansion mechanism, notably its sequential and reversible configuration that permits the derivation of subsequent round keys from any obtained round key. To counteract these vulnerabilities, we introduce a novel key expansion strategy that leverages dynamic Substitution-boxes (S-boxes) alongside the innovative application of cross-coupled lattice mapping. Our approach includes the development of a new one-dimensional chaotic map integrated into the cross-coupled map lattice to enhance its chaotic dynamics. Utilizing this enhanced lattice, we devise a dynamic S-box generation method. This method, rooted in the cross-coupled lattice mapping of a spatiotemporal chaotic system, yields an S-box with unique security features. Rigorous testing and validation demonstrate the S-box's superior defense against a broad spectrum of cryptographic threats. Furthermore, by embedding cross-coupled lattice mapping into the key expansion routine, we elevate the algorithm's complexity and render it non-reversible. This iterative implementation of the lattice mapping negates the possibility of deducing any round key or the original key from a single round key. Exhaustive experimental analyses validate the proposed key expansion algorithm's independence and adaptability, underscoring its improved security capabilities. The algorithm exhibits robust resistance to conventional side-channel and differential attacks, performing exceptionally in real-world application scenarios. Our study delivers a groundbreaking key expansion methodology that significantly enhances cryptographic security, offering a substantial contribution to the encryption domain and strengthening the overall security infrastructure of encryption algorithms.