Enhanced Reconfigurable Visual Cryptography Strategies Utilizing Optical Metasurfaces

The secure storage and transmission of information are core measures that ensure data security. Within intricate information landscapes, reconfigurable encryption mechanisms serve as robust defenses against potential breaches of encrypted data. Here, we propose a reconfigurable visual secret sharing (VSS) encryption strategy that leverages the capabilities of optical metasurfaces and exhibits a dual-channel secondary encryption scheme. This method employs three shared keys (SKs) hidden in the near-field and spin-decoupled far-field channels of the metasurface to perform the initial encryption, enabling the decryption of two distinct encrypted information. Subsequently, leveraging clues from the initial decryption process, the SKs in two far-field channels, in conjunction with the corresponding reconfigurable codebook, can achieve dual-channel reconfigurable encryption. As a proof of concept, we conduct experiments to decrypt the first-time encrypted information and the secondary encrypted information that is reconfigurable. The enhanced reconfigurable encryption strategy not only improves the information security and parallel encryption capacity but also offers repetitive encryption and dynamic encryption without updating the metasurface hardware.