# Quantitative Information Flow and the Lattice of Information

## Pasquale Malacaria

(Queen Mary London)

Real systems leak confidential information, so instead of asking if a system is secure the question should be "how much" secure a system is. Quantitative Information Flow is a growing field whose aim is to address this question by measuring the leakage of confidential information in computer systems. We describe the Lattice of Information as a foundation for Quantitative Information Flow. We investigate the mathematical properties of this lattice and their relation to information theory and recent work in the area. In particular algebraic properties will be shown to simplify and clarify Quantitative Information Flow concepts as analysis of loops. Other properties like a metric distance on Lattice points will be shown to be relevant in providing robust yet tolerant declassification policies.

**Thursday 30th April 2009, 14:00**

Digital Technium, Room 05 (Access Grid Room) - Joint Seminar with Bath University

Department of Computer Science