Lightweight hash function based on affine transformation S-box

Linear layer of lightweight hash functions is ordinarily too simple to resist statistical saturation attack. A novel lightweight hash function is proposed, which is based on the sponge structure and inspired by affine transformation S-box. The affine transformation S-box inherit the excellent cryptographic properties of original S-box, and offset lack of simple linear layer to a great extent as well. The original 4 bit S-box is selected by computing numbers of differential pairs with the largest differential probability, masks with the best linear approximation and maximum branch number of optimal S-box affine equivalent classes. Security of holistic and internal primitives is analyzed with differential and linear cryptanalysis, and especially statistical saturation attack. The control logic of affine transformation structure and the serial/parallel hardware architecture are designed and synthesized by Design Compiler. The results show that in case of adding a few control logic, the lightweight hash function with affine transformation S-box increases difficulty of tracing specific bit in diffusion trail, that is, structures of affine transformations increase confusion of linear diffusion layer and improve the ability against statistical saturation attack.