Fault‐Tolerant Encryption with Shamir's Secret Sharing Metasurface

Abstract Secret‐sharing metasurfaces provide a new platform for the transmission of distributed cryptographic images, greatly enhancing the security of optical encryption. In view of the situation in practical applications where keys are prone to loss or tampering, a novel secret sharing encryption scheme enabled by the metasurface technology is proposed. Shamir's secret sharing strategy is first utilized to divide the secret information into four shares, providing the first layer of algorithmic encryption. These secret shares are further embedded into four distinct QR code images, which are physically implemented via a metasurface platform, achieving a second layer of hardware‐level encryption. The scheme is numerically validated using a bilayer silicon metasurface designed with bidirectional asymmetric circular‐to‐linear polarization conversion capability, enabling nanostructure orientation angle decoupled 4‐bit intensity encoding to ensure secure access to the four binary images under different illumination directions and polarization states. Based on the shares extracted from the four QR code images, the secret information is successfully reconstructed via the Lagrange interpolation. The demonstrated method combines optical encryption with polynomial calculation, enhancing both digital and physical security, and shows strong potential applications in data storage, optical display, and distributed secure communication.