Security Type Checking for MILS-AADL Specifications

Information flow policies are widely used for specifying confidentiality and integrity requirements of security-critical systems. In contrast to access control policies and security protocols, they impose global constraints on the information flow and thus provide end-to-end security guarantees. The information flow policy that is usually adopted is non-interference. It postulates that con dential data must not affect the publicly visible behavior of a system. However, this requirement is usually broken in the presence of cryptographic operations. 

In this paper, we provide an extended definition of non-interference for systems that are specified in a MILS variant of the Architecture Analysis and Design Language (AADL). More concretely, we propose a type system for MILS-AADL component definitions that distinguishes between breaking non-interference because of legitimate use of sufficientlynbsp;strong encryption and breaking non-interference due to annbsp;unintended information leak. To this aim, it tracks bothnbsp;intra- and inter-component information flow and considersbr /> both data- and event-flow security./p>