Abstract non-interference in a fragment of Java bytecode

Abstract

This work presents a program analyzer for checking Abstract Non-Interference in a fragment of Java bytecode. Abstract Non-Interference is an information flow property which is weaker and more general than standard Non-Interference, since it can allow some selected parts of secret information to flow into the public part of a program. The motivation for such a weakening is that some flows are indeed useful in real-life applications. The amount of allowed flows is encoded into abstract domains, which characterize the degree of precision of a potential attacker in observing data; flows are forbidden as long as they can be observed and exploited by attackers. Abstract values describe possible values of programs in different executions. Basic features of Java bytecode are considered; advanced topics, such as method calls, objects and exceptions, are also discussed. A program is said to be secure if analysis computes a state which does not contain private information in public places; information flows can exist only as long as the attacker has not enough observational power to see and exploit them.