Cryptology ePrint Archive: Report 2014/264

Continuous After-the-fact Leakage-Resilient Key Exchange (full version)

Janaka Alawatugoda and Colin Boyd and Douglas Stebila

Abstract: Security models for two-party authenticated key exchange (AKE) protocols have developed over time to provide security even when the adversary learns certain secret keys. In this work, we advance the modelling of AKE protocols by considering more granular, continuous leakage of long-term secrets of protocol participants: the adversary can adaptively request arbitrary leakage of long-term secrets even after the test session is activated, with limits on the amount of leakage per query but no bounds on the total leakage. We present a security model supporting continuous leakage even when the adversary learns certain ephemeral secrets or session keys, and give a generic construction of a two-pass leakage-resilient key exchange protocol that is secure in the model; our protocol achieves continuous, after-the-fact leakage resilience with not much more cost than a previous protocol with only bounded, non-after-the-fact leakage.

Category / Keywords: cryptographic protocols / leakage resilience, key exchange, continuous leakage, after-the-fact, security models

Original Publication (with minor differences): The 19th Australasian Conference on Information Security and Privacy (ACISP 2014)

Date: received 14 Apr 2014

Contact author: janaka alawatugoda at qut edu au

Available format(s): PDF | BibTeX Citation

Version: 20140420:154032 (All versions of this report)

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