An advanced encryption standard (AES) engine with real time S-box generation includes a Galois field multiplier system in a first mode responsive to a first data block for generating an AES selection (S-box) function by executing the multiplicative increase in GF.sup.1(2.sup.m) and applying an affine over GF(2) transformation to obtain a subbyte transformation; and a shift register system for transforming the subbyte transformation to obtain a shift row transformation; the Galois field multiplier system is responsive in a second mode to the shift row transformation to obtain a mix column transformation and add a round key for generating in real time an advanced encryption standard cipher function of the first data block.