Hierarchical Physical‐Cyber Encryption via Metasurface‐Encoded Holographic Keys

ABSTRACT Physical‐layer encryption based on metasurfaces has emerged as a promising alternative to conventional algorithmic cryptography by embedding security into physical processes. However, most existing metasurface‐based encryption schemes operate within single‐stage or static frameworks, where correct physical illumination directly reveals the hidden information, leaving them vulnerable once the physical key is exposed. Here, we propose a hierarchical physical‐cyber cryptographic framework that synergistically integrates meta‐hologram with dynamic digital protocols to overcome these limitations. The system employs a polarization‐multiplexed metasurface to generate two independent holographic keys through spin‐decoupling wavefront control, establishing a three‐stage cyber‐decryption protocol to combine hardware‐level unclonability with digital algorithmic security. To address the intrinsic noise of physical channels, a robust extraction interface based on amplitude thresholding and grid statistics is further introduced, bridging physical outputs with digital logic and enabling reliable recovery of structured keys from holographic reconstructions under practical interference conditions. Experimental validation in the microwave band confirms stable decryption performance with strong noise resilience, successfully recovering concealed information through sequential physical reconstruction and cryptographic processing. Owing to its inherent frequency‐band universality, the proposed scheme is readily extendable to terahertz and optical frequencies, offering a scalable paradigm for multi‐band secure communication systems. By embedding cryptographic strength in physically unclonable processes, this work not only provides a versatile and intrusion‐resistant framework for next‐generation information protection.