Carlo Blundo Stelvio Cimato Sabrina De Capitani di Vimercati Alfredo De Santis Sara Foresti Stefano Paraboschi Pierangela Samarati Efficient Key Management for Enforcing Access Control in Outsourced Scenarios. 364-375 2009 SEC http://dx.doi.org/10.1007/978-3-642-01244-0_32 conf/sec/2009 db/conf/sec/sec2009.html#BlundoCVSFPS09