International Association
for Cryptologic Research

Wireless-channel key exchange (WiKE) protocols that leverage Physical Layer Security (PLS) techniques could become an alternative solution for secure communication establishment, such as vehicular ad-hoc networks, wireless IoT networks, or cross-layer protocols.

In this paper, we provide a novel abstraction of WiKE protocols and present the first game-based security model for WiKE. Our result enables the analysis of security guarantees offered by these cross-layer protocols and allows the study of WiKE's compositional aspects. Further, we address the potential problem of the slow-rate secret-key generation in WiKE due to inadequate environmental conditions that might render WiKE protocols impractical or undesirably slow. We explore a solution to such a problem by bootstrapping a low-entropy key coming as the output of WiKE using a Password Authenticated Key Exchange (PAKE). On top of the new security definition for WiKE and those which are well-established for PAKE, we build a compositional WiKE-then-PAKE model and define the minimum security requirements for the safe sequential composition of the two primitives in a black-box manner. Finally, we show the pitfalls of previous ad-hoc attempts to combine WiKE and PAKE.