Hybrid Authenticated Key Exchange (AKE) protocols combine keying material from different sources (for instance, post-quantum and classical secure key exchange primitives) to build protocols that are resilient to catastrophic failures of the different components. In this talk, I will present the results of a recent work with Torben Hansen and Kenny Paterson: a new hybrid key exchange protocol called Muckle - a simple one-round-trip key exchange protocol that combines preshared keys, post-quantum and classical key encapsulation mechanisms, and quantum key distribution protocols. I will also discuss a general framework HAKE for the analysis of hybrid AKE protocols, and demonstrate the security of our approach with respect to a powerful attacker, capable of fine-grained compromise of different cryptographic components. HAKE is broad enough to allow us to capture forward secrecy, multi-stage key exchange security, and post-compromise security. I will present an implementation of our Muckle protocol, instantiating our generic construction with classical and post-quantum Diffie-Hellman-based algorithmic choices and discuss the results of benchmarking exercises against our implementation.
Ben Dowling is a postdoc at ETH Zurich, in the Applied Cryptography group headed by Prof. Kenny Paterson since July 2019, and was previously a postdoc in the Information Security Group at Royal Holloway, University of London from January 2017. His research interests focus primarily in provable security of real-world cryptographic protocols, in particular, expanding the frameworks used in the analysis of security protocols to cover novel properties and dependencies not currently examined in literature.