Efficient substitution boxes have crucial importance in the design of cryptographically strong modern block encryption algorithms. They are the only nonlinear blocks that decide the security strength of entire cryptosystem. In this paper, a meta-heuristic approach based on Ant Colony Optimization and chaos is put forward to retrieve a suitable configuration of strong 8×8 substitution box. The optimization is carried out by transforming initial S-box to travelling salesman problem through edge matrix. The cryptographic strength of optimized S-box is investigated against standard tests such as bijectivity, nonlinearity, strict avalanche criterion, output bits independence criterion and differential approximation probability. The performance comparison of generated S-box with some recent chaos-based S-boxes evidently proves that the proposed scheme is proficient to discover strong nonlinear component of block encryption systems.
Ahmad, M., Bhatia, D., & Hassan, Y. (2015). A Novel Ant Colony Optimization Based Scheme for Substitution Box Design. In Procedia Computer Science (Vol. 57, pp. 572–580). Elsevier. https://doi.org/10.1016/j.procs.2015.07.394