Random Search Based Efficient Chaotic Substitution Box Design for Image Encryption

Cryptographic Substitution-boxes are source of nonlinearity in modern block encryption systems. The robustness and confusion imparted through these systems heavily rely on the strength of their S-boxes. This brings new challenges to design cryptographically potent S-boxes to develop strong encryption systems. In this paper, an effective method to design efficient 8×8 S-box is proposed. The design methodology incorporates piece-wise linear chaotic map based random search. The S-box obtained by the proposed methodology is tested against standard statistical tests like bijective property, strict avalanche criteria, nonlinearity, differential uniformity, bits independent criteria, and linear approximation probability, revealing its outstanding performance. The proposed S-box is compared with some recent chaos-based 8×8 S-boxes. Moreover, the proposed S-box is applied to encrypt plain-image with proposed S-box transformation to unveil and highlight its inherent great encryption strength. The results confirm that the design is consistent and suitable for building strong encryption systems for secure communication.