Lock‐Key Cascaded Metasurfaces for Secure Holographic Encryption

ABSTRACT Metasurface‐based encryption provides a compact hardware route to physical‐layer information protection, yet integrating multiple configuration‐dependent access channels within a shared microwave platform remains challenging. Here, we introduce a microwave Lock‐Key metasurface architecture comprising compact physical Keys and a larger shared Lock for configuration‐dependent physical‐layer encryption. Physical Key identity, flipping state, and 3D position relative to the shared Lock jointly define prescribed configurations that map onto distinct cascaded holographic reconstruction channels. Access control is thereby embedded in the prescribed physical configuration. A multi‐objective framework based on analytically derived Pearson correlation coefficient gradients jointly optimizes the phase patterns of the Keys and the shared Lock under coupled standalone and cascaded reconstruction constraints. Numerical simulations and microwave experiments demonstrate effective encryption and reconstruction of holographic information across various prescribed Lock‐Key cascaded configurations, verifying the feasibility of hardware‐based physical‐layer encryption. This work provides a shared‐hardware route toward physical‐layer encryption, hardware‐based authentication and secure information transmission in wireless and Internet‐of‐Things systems.