A contextual multilevel access control model with default and exception description logic

The proposed multilevel access control model is based on description logic augmented with default and exception to capture the context feature. In this model, the level is assigning to the role of the user instead of the subject, and to the view instead of the object. All subjects who play a role have the same level of clearance and all objects that belong to the same view have the same classification level. A subject is authorized to access to the object if its clearance level is greater than or equal to the classification level of object in a given context. The context allows us to provide dynamic authorization.