We discuss a novel role locking protocol (RLP) to prevent illegal information flow among objects in a role-based access control (RBAC) model. In this paper, we define a conflicting relation among roles "a role R1 conflicts with another role R2" to show that illegal information flow may occur if a transaction associated with role R1 is performed before another transaction with role R2. Here, we introduce a role lock on an object to abort a transaction with role R1 if another transaction with role R2 had been already performed on the object. Role locks are not released even if transactions issuing the role locks commit. After data in an object o1 flow to another object o2, if the object o1 is updated, the data in the object o2 is independent of the object o1, i.e. obsolete. A role lock on an object can be released if information brought into the object is obsolete. We discuss how to release obsolete role locks. We also discuss how to implement the role locking protocol in single-server and multi-server systems.
Optimal pricing in multi server systems
