Extending the GWV Security Policy and Its Modular Application to a Separation Kernel

Nowadays formal methods are required for high assurance security and safety systems. Formal methods allow a precise specification and a deep analysis of system designs. However, usage of formal methods in a certification process can be very expensive. In this context, we analyse the security policy proposed by Greve et al in the theorem prover Isabelle/HOL. We show how this policy with some extensions can be applied in a modular way, and hence, reduce the number of formal models and artifacts to certify. Thus, we show how the security policy for a separation kernel is derived from the security policy of the micro-kernel that forms the basis of the separation kernel.We apply our approach to an example derived from an industrial real-time operating system.