PWLCM-Based Random Search for Strong Substitution-Box Design

Substitution-boxes are the only source of nonlinearity in various symmetric encryption systems and responsible for inducing confusion of plaintext data. The robustness of these systems exclusively depends on the potentiality of S-boxes. The design methods having fast and simple computations which can yield effective S-boxes are preferred. In this paper, a new chaos-based random search is applied to construct cryptographically potent 8 × 8 S-box. The method explores the features of piecewise linear chaotic map for candidate generation and random search. The optimized S-box obtained is tested against standard statistical tests like bijectivity, equiprobable I/O XOR distribution, nonlinearity, and strict avalanche criteria revealing its superior performance. The proffered substitution-box is further compared with some contemporary chaotic substitution-boxes. The results confirm a consistent design, suitable for building strong block encryption systems.