Types vs. PDGs in Information Flow Analysis

Type-based and PDG-based information flow analysis techniques are currently developed independently in a competing manner, with different strengths regarding coverage of language features and security policies. In this article, we study the relationship between these two approaches. One key insight is that a type-based information flow analysis need not be less precise than a PDG-based analysis. For proving this result we establish a formal connection between the two approaches which can also be used to transfer concepts from one tradition of information flow analysis to the other. The adoption of rely-guarantee-style reasoning from security type systems, for instance, enabled us to develop a PDG-based information flow analysis for multi-threaded programs.