Abstract. Static analysis is a powerful technique for automatic verification of programs but raises major engineering challenges when developing a full-fledged analyzer for a realistic language such as Java. Efficiency and precision of such a tool rely partly on low level components which only depend on the syntactic structure of the language and therefore should not be redesigned for each implementation of a new static analysis. This paper describes the Sawja library: a static analysis framework fully compliant with Java 6 which provides OCaml modules for efficiently manipulating Java bytecode programs. We present the main features of the library, including i) efficient functional data-structures for representing program with implicit sharing and lazy parsing, ii) an intermediate stack-less representation, and iii) fast computation and manipulation of complete programs. We provide experimental evaluations of the different features with respect to time, memory and precision.

Abstract. Static analysers are becoming so complex that it is crucial to ascertain the soundness of their results in a provable way. In this paper we develop a certified checker in Coq that is able to certify the results of a polyhedral array-bound analysis for an imperative, stack-oriented bytecode language with procedures, arrays and global variables. The checker uses, in addition to the analysis result, certificates which at the same time improve efficiency and make correctness proofs much easier. In particular, our result certifier avoids complex polyhedral computations such as convex hulls and is using easily checkable inclusion certificates based on Farkas lemma. Benchmarks demonstrate that our approach is effective and produces certificates that can be efficiently checked not only by an extracted Caml checker but also directly in Coq.

Abstract. Abstract interpretation-based proof carrying code uses post-fixpoints of abstract interpretations to witness that a program respects a safety policy. Some witnesses carry more information than needed and are therefore unnecessarily large. We introduce a notion of size of a witness and propose techniques for reducing the size of such certificates. For distributive analyses, we show that a smallest witness exist and we give an iterative algorithm for computing it. For non-distributive analyes we propose a technique for pruning a witness and illustrate this pruning on a relational, polyhedra-based analysis. Finally, only the existence of a witness is needed to assure the code consumer of the safety of a given program. This makes possible a compression technique of witnesses where only part of a witness is sent together with an encoding of the iterative steps necessary to prove that it is part of a post-fixpoint.