Epistemic Temporal Logic for Information Flow Security

TL;DR

This paper introduces an epistemic temporal logic framework to reason about knowledge evolution in programs, effectively capturing information flow security properties like noninterference and declassification.

Contribution

It combines temporal epistemic logic with computational models to analyze how agents' knowledge changes through program execution, addressing complex security policies.

Findings

Captures standard noninterference and declassification notions

Models sensitive and public data interactions

Provides a formal reasoning framework for information flow

Abstract

Temporal epistemic logic is a well-established framework for expressing agents knowledge and how it evolves over time. Within language-based security these are central issues, for instance in the context of declassification. We propose to bring these two areas together. The paper presents a computational model and an epistemic temporal logic used to reason about knowledge acquired by observing program outputs. This approach is shown to elegantly capture standard notions of noninterference and declassification in the literature as well as information flow properties where sensitive and public data intermingle in delicate ways.