The weaknesses of usage control (UCON) model was pointed out,and the context was introduced to replace a generalized system and the environment in UCON to extend it into a contextual usage control(CUC) model.The management function was also introduced,enabling management and control to some extent together.CUC’s architecture includes two major functional blocks,one called as management block for the management of attributes of subjects,objects and contexts,and the other called as control block for access control itself.There is loosely couple between the two functional blocks.After the conceptual description of CUC,an algebra approach was used for formal description of CUC syntax and semantics.
