An apparatus for generating round-key words in accordance with a Rijndael algorithm. In one embodiment of the invention, the apparatus includes (a) a key expansion register block, having a key expansion register adapted to receive a final cipher key of a key expansion schedule in accordance with the Rijndael algorithm; (b) a round constant generator; (c) a first XOR adder adapted to add a first word of the key expansion register to a second word to generate and provide a first sum to the key expansion register block; (d) a transformation block adapted to generate a transformed word based on the first sum and the current round constant over four counts of a first cyclical counter; and (e) a second XOR adder adapted to add the transformed word to the first word of the key expansion register to generate and provide a second sum to the key expansion register block.