Applying the dependability paradigm to computer security

Dependability is that property of a computer system such that reliance can justifiably be place on the service it delivers. In this paper, we contrast the way different ways faults are handled in the dependability paradigm with the way they are handled in the current paradigms for secure system design. We show how the current security paradigm is generally restricted to a subset of the types of approaches used in dependability, largely concentrating on fault prevention and removal while neglecting fault tolerance and forecasting, and we argue that this paradigm is fast becoming obsolete. We discuss the implications of extending the security paradigm to cover the full range of options covered by dependability. In particular, we develop a rough outline of a fault model for security and show how it could be applied to better our understanding of the place of both fault tolerance and fault forecasting in computer security