David A. Naumann

Minh Ngo, David A. Naumann, Tamara Rezk

This work provides a study to demonstrate the potential of using off-the-shelf programming languages and their theories to build sound language-based-security tools. Our study focuses on information flow security encompassing declassification policies that allow us to express flexible security policies needed for practical requirements. We translate security policies, with declassification, into an interface for which an unmodified standard typechecker can be applied to a source program---if the program typechecks, it provably satisfies the policy. Our proof reduces security soundness---with declassification---to the mathematical foundation of data abstraction, Reynolds' abstraction theorem.

Mounir Assaf, David A. Naumann

Fine grained information flow monitoring can in principle address a wide range of security and privacy goals, for example in web applications. But it is very difficult to achieve sound monitoring with acceptable runtime cost and sufficient precision to avoid impractical restrictions on programs and policies. We present a systematic technique for design of monitors that are correct by construction. It encompasses policies with downgrading. The technique is based on abstract interpretation which is a standard basis for static analysis of programs. This should enable integration of a wide range of analysis techniques, enabling more sophisticated engineering of monitors to address the challenges of precision and scaling to widely used programming languages.

François Dupressoir, Andrew D. Gordon, Jan Jürjens et al.

We describe how to verify security properties of C code for cryptographic protocols by using a general-purpose verifier. We prove security theorems in the symbolic model of cryptography. Our techniques include: use of ghost state to attach formal algebraic terms to concrete byte arrays and to detect collisions when two distinct terms map to the same byte array; decoration of a crypto API with contracts based on symbolic terms; and expression of the attacker model in terms of C programs. We rely on the general-purpose verifier VCC; we guide VCC to prove security simply by writing suitable header files and annotations in implementation files, rather than by changing VCC itself. We formalize the symbolic model in Coq in order to justify the addition of axioms to VCC.