Walsh Spectral Analysis of the SMS4 S-Boxes Boolean Functions
S-Boxes are quite important components of modern symmetric cryptosystems in the sense that S-Boxes bring nonlinearity to block ciphers and strengthen their cryptographic security. Uses the theory of Walsh spectrum to analyse the SMS4 characteristics such as linearity, nonlinearity, balanceness, strict avalanche criteria and propagation criteria in order to reveal the security of SMS4 S-box theoretically.