AES Based on Key Dependently Nonlinear Redundant S-Box

The AES S-Box is the only part of the standard responsible for providing the nonlinearity needed to deal with the linear and differential attacks. This fact emphasizes the necessity for the AES S-Box to possess high nonlinearity and low differential uniformity. However, it was proved that all the component Boolean functions of the AES S-Box, which is constructed by the finite field inversion, are linearly redundant. In this paper, the authors proposed a new version of AES based on nonlinear redundant S-Box with good cryptographic properties. For that, the construction of an initial S-Box over the finite field is guided by a key dependently selected irreducible polynomial. After that, the linear redundancy is progressively reduced from the component Boolean functions of the initial S-Box thro ugh a new technique called 2-bits-tweak. Additionally, the authors analyzed the performance of their scheme.