Action systems for security specification

To be generally useful a theory must be both intellectually sound and practically applicable. We consider the noninterference approach to security specification, focusing in particular on Roscoe´s work on nondeterminism. This provides a starting point for reflecting on what features are desirable in a development method for secure systems. In an attempt to meet at least some of these requirements we use action systems which combine both event and state-based specification approaches. Using Butler´s correspondence between action systems and CSP we define determinism and security properties directly in action systems. We give examples of the action system approach and discuss its advantages and disadvantages