A general obligation model and continuity: enhanced policy enforcement engine for usage control.

Basel Katt Xinwen Zhang Ruth Breu Michael Hafner Jean-Pierre Seifert A general obligation model and continuity: enhanced policy enforcement engine for usage control. 123-132 2008 SACMAT http://doi.acm.org/10.1145/1377836.1377856 conf/sacmat/2008 db/conf/sacmat/sacmat2008.html#KattZBHS08