Using Security Methods to Enforce Mandatory and Discretionary Access Control in an Object Database

In this paper, we propose a new security enforcement mechanism and demonstrate how this mechanism can enforce policies for both mandatory access control (MAC) and discretionary access control (DAC) in an object database system. Each class may have a security method that can block messages that leave instances of the class, and can block messages directed to instances of the class. Each superclass controls the invocation of security methods in its subclasses. A subclass cannot override the security methods in its superclasses, but the subclass can extend those security methods. The mandatory access control policy is enforced by a single security method along with other methods in the highest class in the class hierarchy. The discretionary access control policy is enforced by a single security method along with other methods a subclass of the highest class.