Challenge-Response Physical Layer Authentication over Partially Controllable Channels

Challenge-response is a security mechanism well known for authentication using encryption. In this article, we propose new challenge-response mechanisms in the context of physical layer security. The verifier, instead of sending a challenge, changes the physical properties of the electromagnetic environment and expects to receive a properly modified signal from the device under verification. We thus introduce the concept of partially controllable channels that enable such signal propagation medium changes. We also show that current and future communication systems already entail several examples of such partially controllable channels, for example, when using intelligent reflective surfaces (IRSs) or relays, or for communications among drones. Several security issues associated with the new challenge-re-sponse mechanisms are discussed, and future topics to be investigated are outlined.