Constructing an enhanced variant of Hill cipher based on 2D hyper chaotic map over GF(2^ <i>n</i> )

The inherent linearity of Hill cipher renders it vulnerable to security threats, such as known-plaintext attacks. To solve this problem, an enhanced variant was designed by extending the Hill cipher from the integer ring to the finite field. First, a 2D finite field hyper chaotic map (2D-FFHCM) with desirable dynamical properties was constructed to dynamically generate both the invertible key matrices (via the product of invertible triangular matrices) and a strong S-Box. Subsequently, an enhanced variant of Hill cipher based on the S-Box was constructed, achieving strong confusion and diffusion properties. Finally, the proposed algorithm was evaluated through comprehensive tests, including key space, key sensitivity, information entropy, differential attack analysis and correlation analysis. Experimental results demonstrated the excellent performance of the proposed algorithm, confirming it can effectively resist common cryptographic attacks.