Testing Decision Procedures for Security - by - Contract ∗

The traditional realm of formal methods is the off-line verification of formal properties of hardware and software. In this paper we report a different approach that uses formal methods (namely the integration of automata modulo theory with decision procedures) on-the-fly, at the time an application is downloaded on a mobile application such as PDA or a smart phone. The idea behind security-by-contract is that a mobile application comes equipped with a signed contract describing the security relevant behavior of the application and such contract should be matched against the mobile platform policy. Both are specified as special kinds of automata and the operation is just an on-the-fly emptiness test over two automata modulo theories where edges are not just finite states of labels but rather expressions that can capture infinite transitions such as “connect only to urls starting with https://”. The paper describe the prototype implementation, its integration with a state of the art decision solver (based on MathSAT and NuSMV) and the preliminary experiments that we have done for contract-policy matching.