Leakage of confidential information represents a serious security risk. Despite a number of novel, theoretical advances, it has been unclear if and how quantitative approaches to measuring leakage of confidential information could be applied to substantial, real-world programs. This is mostly due to the high complexity of computing precise leakage quantities. In this paper, we introduce a technique which makes it possible to decide if a program conforms to a quantitative policy which scales to large state-spaces with the help of bounded model checking.Our technique is applied to a number of officially reported information leak vulnerabilities in the Linux Kernel. Additionally, we also analysed authentication routines in the Secure Remote Password suite and of a Internet Message Support Protocol implementation. Our technique shows when there is unacceptable leakage; the same technique is also used to verify, for the first time, that the applied software patches indeed plug the information leaks. This is the first demonstration of quantitative information flow addressing security concerns of real-world industrial programs.

No abstract

Abstract. We present the information theoretical basis of Quantitative Information Flow. We show the relationship between lattices, partitions and information theoretical concepts and their applicability to quantify leakage of confidential information in programs, including looping programs.We also report on recent works that use these ideas to build tools for the automatic quantitative analysis of programs. The applicability of this information theoretical framework to the wider context of network protocols and the use of Lagrange multipliers in this setting is also demonstrated.

No abstract