Described is an apparatus comprising an S-box circuitry operable to convert a value on an input into a value on an output in accordance with an Advanced Encryption Standard (AES) Rijndael S-box matrix. The apparatus also comprises a pseudo-random number generation (PRG) circuitry operable to provide a sequence of pseudo-random numbers on a first output and a registered copy of the sequence on a second output. The apparatus further comprises a mask circuitry operable to provide an XOR of a value on the output of the S box circuitry and a value on the first output of the PRG circuitry. The apparatus additionally comprises a mask removal circuitry operable to provide an XOR of a value on an output of the data register circuitry, a value coupled to an output of a key register circuitry, and a value on the second output of the PRG circuitry.