Software Verification of Hyperproperties Beyond k-Safety
Raven Beutner, Bernd Finkbeiner
Temporal hyperproperties are system properties that relate multiple execution traces. For (finite-state) hardware, temporal hyperproperties are supported by model checking algorithms, and tools for general temporal logics like HyperLTL exist. For (infinite-state) software, the analysis of temporal hyperproperties has, so far, been limited to k-safety properties, i.e., properties that stipulate the absence of a bad interaction between any k traces. In this paper, we present an automated method for the verification of ∀k∃l-safety properties in infinite-state systems. A ∀k∃l-safety property stipulates that for any k traces, there exist l traces such that the resulting k+l traces do not interact badly. This combination of universal and existential quantification allows us to express many properties beyond k-safety, including, for example, generalized non-interference or program refinement. Our method is based on a strategy-based instantiation of existential trace quantification combined with a program reduction, both in the context of a fixed predicate abstraction. Importantly, our framework allows for mutual dependence of strategy and reduction.
CAV Distinguished Paper Award 2022.