An Expression Method to Implement S-Box and Inverse S-Box Substitution for AES Algorithm

S-Box substitution and inverse S-Box substitution are the major bottleneck for AES algorithm,which directly affect the speed of AES chip.On the basis of optimizing Q-M simplifying method,this paper proposes an expression method to implement the S-Box substitution and inverse S-Box substitution in AES algorithm.Compared with the widespread use of the look-up-table method,the expression method can reduce the delay,area and power of circuit by 8.5%,27.4% and 17% respectively.