Wireless physical-layer encryption with programmable metasurface in real environment

Wireless communication with physical layer security is of great importance in modern society, especially with the advent of the Internet-of-Things, fifth-generation communication, and beyond. More recently, metasurface-enabled physical-level encryption methods have attracted researchers' attention, in which the programmable metasurface is introduced as a controllable temporal entropy source. In this work, we present a novel approach to wireless physical-layer encryption by exploring the programmable metasurface as the high temporal-spatial entropy source via its unique capability in manipulating a flexibly temporal-spatial electromagnetic wavefront. We implement a proof-of-principle system working at around 2.4 GHz and develop associated efficient algorithms for the generation of a physical-level encryption key, where the programmable metasurface and surrounding environment are treated as a whole in a deterministic way. We experimentally demonstrate that the proposed method enables us to generate the Mbps-rate encryption key with the high spatial-temporal entropy in real-world settings. Our work could pave the way toward the next generation of model-free physical-layer secure wireless communication.