Flexible meaningful visual multi-secret sharing scheme by random grids

With rapid developments in network technology, information security is becoming increasingly crucial. To ensure that secret images are not being stolen during transmission, a good countermeasure is to encrypt them before transmission. Visual secret sharing (VSS) is a type of secure communication technology in which a secret image is encrypted into some shares and then restored through human vision by superimposing shares. A random grid is a pivotal VSS technique. Because computation and pixel expansion is not needed in the decrypting phase, many scholars have researched random grids for VSS. To minimize time consumption, some researchers have proposed high-capacity visual multiple secret sharing (VMSS) schemes that can encrypt multiple images simultaneously, although some difficulty is encountered in share management. A meaningful VSS scheme provides a solution for both distinguishing and management problems; however, it cannot handle restrictions on the number of secret images. For avoiding the abovementioned problems, this study proposes an advanced meaningful VMSS scheme that can flexibly adjust the quality between shares and restored images. Our scheme offers seven attractive features that make it notably flexible in theoretical and practical use.