Advanced Physical Layer Metasurface‐Empowered Cryptography with Robustness, High Capacity, and Enhanced Security

Abstract Physical layer metasurface‐empowered cryptography offers a novel approach to secure encryption. This study proposes an encryption method with robustness, high capacity, and enhanced security based on the dual‐band complex‐amplitude metasurface. By leveraging the American Standard Code for Information Interchange (ASCII), both the secret message and the compressed digital signature are encrypted and transmitted together, eliminating codebook transmission and reducing security risks. The modified Visual Secret Sharing (VSS) scheme is employed to strengthen the security, fidelity, and robustness. Additionally, a three‐dimensional wavefront reconstruction algorithm is used to increase the encryption capacity, and a multivariate encryption key provides an extra layer of protection. A prototype metasurface sample is designed, fabricated, and characterized as a proof‐of‐concept demonstration. The measured results closely match the numerical ones and the design objective, confirming the viability and resilience of this high‐capacity, enhanced security encryption method for applications in anti‐counterfeiting and secure data transmission.