Enhancing the Robustness of Block Ciphers through a Graphical S-Box Evolution Scheme for Secure Multimedia Applications

Abstract

Abstract Block ciphers, which serve as primary components of network security systems, play a crucial role in securely exchanging and communicating confidential information. Substitution boxes (S-boxes) are the most significant components of contemporary block ciphers. Inherently, the security strength of such cryptosystems relies on the quality of the S-box employed. The cryptographically strong S-boxes provide robustness and assurance of the security competency to block ciphers. To generate the strong S-boxes, a number of chaos-based methods have been investigated in the past decade. However, chaos-based methods are random approaches which are computationally intensive and don’t guarantee the generation of strong S-boxes. To meet the challenges of strong and fast S-box generation, a novel coset graphs based algebraic method is proposed to evolve robust and efficient S-box. Firstly, an initial S-box of decent cryptographic strength is generated by using the vertices of coset graphs for two Galois fields and a bijective function. After that, the initial S-box's robustness is improved by rearranging its columns in a particular manner, which yields the strong proposed S-box. The effectiveness of the proposed method is validated by comparing various attributes of our S-box against some recently investigated S-boxes. Additionally, the generated S-box is applied for image encryption and analyzed using the MLC criterions. The results show the suitability of the proposed S-box for secure multimedia applications.