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.

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@inproceedings {285447,
author = {Olivier Blazy and Ioana Boureanu and Pascal Lafourcade and Cristina Onete and L{\'e}o Robert},
title = {How fast do you heal? A taxonomy for post-compromise security in secure-channel establishment},
booktitle = {32nd USENIX Security Symposium (USENIX Security 23)},
year = {2023},
isbn = {978-1-939133-37-3},
address = {Anaheim, CA},
pages = {5917--5934},
url = {},
publisher = {USENIX Association},
month = aug