Masaaki Fujiyoshi Seungwu Han Hitoshi Kiya Reversible Information Hiding Considering Hierarchical Access Control. 209-212 2009 IAS http://dx.doi.org/10.1109/IAS.2009.116 conf/IEEEias/2009 db/conf/IEEEias/IEEEias2009.html#FujiyoshiHK09