Privacy Policy Specification and Audit in a Fixed-Point Logic - How to enforce HIPAA, GLBA and all that (CMU-CyLab-10-008)

Organizations such as hospitals and banks that collect and use personal information are required to comply with privacy regulations like the Health Insurance Portability and Accountability Act (HIPAA) and the Gramm-Leach-Bliley Act (GLBA). With the goal of specication and enforcement of such practical policies, we develop the logic PrivacyLFP, whose syntax is an extension of the fixed point logic LFP with operators of linear temporal logic. We model organizational processes by assigning role-based responsibilities to agents that are also expressed in the same logic. To aid in designing such processes, we develop a semantic locality criterion to characterize responsibilities that agents (or groups of agents) have a strategy to discharge, and easily checkable, sound syntactic characterizations of responsibilities that meet this criterion. Policy enforcement is achieved through a combination of techniques: (a) a design-time analysis of the organizational process to show that the privacy policy is respected if all agents act responsibly, using a sound proof system we develop for PrivacyLFP; and (b) a posthoc audit of logs of organizational activity that identifies agents who did not live up to their responsibilities, using a model checking procedure we develop for PrivacyLFP. We illustrate these enforcement techniques using a representative example of an organizational process.