Enriching the expressive power of security labels

Common security models such as Bell-LaPadula focus on the control of access to sensitive data but leave some important systems issues unspecified, such as the implementation of read-only objects, garbage collection, and object upgrade and downgrade paths. Consequently, different implementations of the same security model may have conflicting operational and security semantics. We propose the use of more expressive security labels for specifying these system issues within the security model, so that the semantics of a system design are precisely understood and are independent of implementation details