Ryo Nojima Yuichi Kaji Using Trapdoor Permutations in a Complete Subtree Method for Broadcast Encryption. 568-574 http://search.ieice.org/bin/summary.php?id=e88-a_2_568&category=D&year=2005&lang=E&abst= 2005 88-A IEICE Transactions 2 db/journals/ieicet/ieicet88a.html#NojimaK05a