USENIX Security '23: Post-Compromise Security Taxonomy 🔐

USENIX Security '23 - How fast do you heal? A taxonomy for post-compromise security in secure-channel establishment

Olivier Blazy, LIX, CNRS, Inria, École Polytechnique, Institut Polytechnique de Paris, France; Ioana Boureanu, University of Surrey, Surrey Centre for Cyber Security, UK; Pascal Lafourcade, LIMOS, University of Clermont Auvergne, France; Cristina Onete, XLIM, University of Limoges, France; Léo Robert, LIMOS, University of Clermont Auvergne, France

Post-Compromise Security (PCS) is a property of secure-channel establishment schemes, which limits the security breach of an adversary that has compromised one of the endpoint to a certain number of messages, after which the channel heals. An attractive property, especially in view of Snowden’s revelation of mass-surveillance, PCS was pioneered by the Signal messaging protocol, and is present in OTR. In this paper, we introduce a framework for quantifying and comparing PCS security, with respect to a broad taxonomy of adversaries. The generality and flexibility of our approach allows us to model the healing speed of a broad class of protocols, including Signal, but also an identity-based messaging protocol named SAID, and even a composition of 5G handover protocols.

View the full USENIX Security '23 program at https://www.usenix.org/conference/usenixsecurity23/program