DRAKE: Distributed Relay-Assisted Key Establishment

In this paper we propose DRAKE, a distributed relay-Assisted key establishment protocol working at the physical layer of a wireless network. DRAKE leverages the superposition of the signals emitted by dedicated relays to provide a symmetric key to a remote constrained device, by requiring zero transmissions from this device. Requiring zero transmissions from the remote device, DRAKE emerges as a unidirectional and radio stealthy solution, suitable for a number of applications and scenarios, such as tactical communications, stealthiness, and for devices with a limited transmission range, to name a few. Thanks to the combination of a repetition encoder and further error correction at the relays, DRAKE is able to establish a key with a very low error probability. We discuss the security of the DRAKE protocol against a passive eavesdropper, under different realistic assumptions. Finally, we provide the results of a preliminary performance assessment of the protocol, showing outstanding performance both in terms of resilience to random noise and security against adversaries equipped with multiple omnidirectional antennas.