Strongly Leakage-Resilient Authenticated Key Exchange

Abstract

Authenticated Key Exchange AKE protocols have been widely deployed in many real-world applications for securing communication channels. In this paper, we make the following contributions. First, we revisit the security modelling of leakage-resilient AKE protocols, and show that the existing models either impose some unnatural restrictions or do not sufficiently capture leakage attacks in reality. We then introduce a new strong yet meaningful security model, named challenge-dependent leakage-resilient eCK $$\mathsf {CLR\text{- }eCK}$$ model, to capture challenge-dependent leakage attacks on both long-term secret key and ephemeral secret key i.e., randomness. Second, we propose a general framework for constructing one-round $$\mathsf {CLR\text{- }eCK}$$-secure AKE protocols based on smooth projective hash functions SPHFs. Finally, we present a practical instantiation of the general framework based on the Decisional Diffie-Hellman assumption without random oracle. Our result shows that the instantiation is efficient in terms of the communication and computation overhead and captures more general leakage attacks.