Security of Tzeng's Time-Bound Key Assignment Scheme for Access Control in a Hierarchy.

Xun Yi Yiming Ye Security of Tzeng's Time-Bound Key Assignment Scheme for Access Control in a Hierarchy. 1054-1055 2003 15 IEEE Trans. Knowl. Data Eng. 4 http://csdl.computer.org/comp/trans/tk/2003/04/k1054abs.htm db/journals/tkde/tkde15.html#YiY03