New (t, n)-Threshold P-VSS Schemes Using Fewer Types of Polarizers

As network demands increase, encryption becomes increasingly important. Visual secret sharing (VSS) encrypts a secret image into multiple images (called shares) and then superimposes these shares so that the original image can be directly identified by humans. In traditional VSS, black represents 1 and white represents 0. Therefore, traditional VSS decryption methods are viewed as logical OR operations. In 1997, the VSS scheme based on the polarization of the light wave was proposed. It utilizes the fact that light passes through a unidirectional polarizer but cannot pass through two mutually perpendicular polarizers. This scheme is relevant to a logical XOR operation in decryption. However, this scheme does not explain the situation when more than two shares are decrypted. Therefore, a new (t, n)-threshold VSS scheme based on polarization (called (t, n)-threshold P-VSS) was proposed to solve the above problem. In that (t, n)-threshold P-VSS scheme, four types of polarizers were used to design the scheme. In this study, we propose three (t, n)-threshold P-VSS schemes, each using only two or three types of polarizers to effectively reduce the proportion of black pixels in the shares compared with previous work. Experimental results and theoretical analysis prove the safety and effectiveness of these schemes.