Ning Chen Zhiyuan Yan Compact designs of mixcolumns and subbytes using a novel common subexpression elimination algorithm. 1584-1587 2008 ISCAS http://dx.doi.org/10.1109/ISCAS.2008.4541735 conf/iscas/2008 db/conf/iscas/iscas2008.html#ChenY08