Innovative nonlinear component generator inspired by squirrel search algorithm

The most used approach for data encryption is block cipher. One of the most important structures for block cipher algorithms is undoubtedly s-boxes. The s-box structure used in the AES algorithm contains 256 values. Therefore, obtaining powerful s-boxes is a rather difficult search problem. Because the search space is very large (256!). In this study, a new method based on squirrel search algorithm (SSA) is proposed to overcome this problem. The proposed method is displacement-based. In an s-box taken at the entrance, stronger s-box structures are sought by changing the location of the elements. The most important innovation in this study is that the elements to be displaced in the s-box were selected with the positioning states of the SSA. The chaotic Gompertz map was used for the initial population. Four different s-boxes were produced with the method developed thanks to the effective positioning states of SSA. As the fitness function, the nonlinearity value, which is the most important evaluation criterion of an s-box structure, was used. The proposed four s-box structures increased up to 110 nonlinearity values after only 4500 iterations. Here, it has been shown that the algorithm can be effective in all s-boxes by generating four different s-boxes. Considering these results, it has been determined that the proposed method gives more effective results than most methods in the literature.