Combining Security and Safety Principles in Practice

In this paper we present an example of applying a combination of security and safety principles. The Ministry of Defence have been developing a common methodology for security accreditation and safety assurance within the SafSec project [5]. The example described in the paper applies this approach at a detailed level, using aspects of security to support the safety argument and safety techniques to support security accreditation. We show an argument, which uses the dependability by contract approach, and how this is used.