Role locks to prevent illegal information flow among objects

This paper discusses a locking protocol to prevent illegal information flow among objects in a role-based access control model. In this paper, we newly define a conflicting relation "a role R₁ conflicts with another role R₂" to show that illegal information flow may occur if a transaction with R₁ is performed before another transaction with R₂. Here, we newly introduce a role lock on an object to abort a transaction with R₁ if another transaction with R₂ had been already performed on the object. Role locks are not released even if transactions issuing the role locks commit. A role lock on an object can be released if information brought into the object got obsolete. We discuss how to release obsolete role locks.