Patent ID: 7702100
Filing Date: 2010-04-20
Classification: H04L

Abstract:
1. Apparatus for generating round-key words in accordance with a Rijndael algorithm, the apparatus comprising: (a) a key expansion register block comprising a key expansion shift register adapted to receive a first cipher key of a key expansion schedule in accordance with the Rijndael algorithm, wherein the key expansion register block is adapted to shift the contents of the key expansion shift register; (b) a round constant generator adapted to generate a current round constant based on a seed value and in response to a first control signal; (c) a first XOR adder adapted to add a first word of the key expansion shift register to a second word to generate and provide a first sum to the key expansion register block, wherein: (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 shift register to generate and provide a second sum to the key expansion register block; wherein the round constant generator comprises: