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

Olivier Blazy (1, 2) , Ioana Boureanu (3) , Pascal Lafourcade (4) , Cristina Onete (5) , Léo Robert (4)

1 X - École polytechnique
2 GRACE - Geometry, arithmetic, algorithms, codes and encryption
3 UNIS - University of Surrey
4 UCA - Université Clermont Auvergne
5 XLIM - XLIM

Post-Compromise Security (PCS) is a property of securechannel 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.

Domains: Cryptography and Security [cs.CR]

Olivier Blazy, Ioana Boureanu, Pascal Lafourcade, Cristina Onete, Léo Robert. How fast do you heal? A taxonomy for post-compromise security in secure-channel establishment. USENIX 2023 - The 32nd USENIX Security Symposium, Aug 2023, Anaheim, United States. ⟨hal-03815803⟩