High-fidelity decryption technology of Visual Cryptography based on optical coherence operation

Abstract

This paper proposes a high-fidelity decryption technology for secret images based on Visual Cryptography (VC) and optical coherence operation. The secret image is converted into two ciphertext images using the VC encryption algorithm, and loaded into two secret vectors respectively. A coherent optical illumination system is built to align the spatial information of the two secret vectors, and decryption is achieved by generating coherent subtraction at the diffraction center of the image plane, the effect is the same as the “XOR” logic operation between two secret images. Both simulation and optical experiments are compared between the optical coherence “XOR” and “OR” operation, and the decryption results demonstrate that the decryption method based on optical coherence “XOR” logic operation outperforms the method based on optical “OR” logic operation in various evaluation indicators such as Structural Similarity (SSIM), Corresponding Coefficient (CC), and Signal-to-noise ratio (SNR). The decryption method provides a broad prospect for the simple, convenient, and high-fidelity information recovery application of VC.