Abstract: 

We aim here to propose an easier and straightforward method for constructing the substitution table (S-Box) of Advanced Encryption Standard (AES).

The method reduces the steps needed to compute the multiplicative inverse, where the multiplicative inverse of an input byte can be computed in clear steps using an iterated formula. It also computes the matrices multiplication (multiplying the multiplicative inverse matrix by the characteristic matrix) without a need to use the characteristic matrix, where this multiplication can be determined directly from the multiplicative inverse using simple XOR operations. The result is a modern method constructing the S-Box.