Information Theory and Security: Quantitative Information Flow

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.