The (n, n) Visual Multi-Secrets Sharing Scheme with Abilities of OR and XOR Decryption

Naor and Shamir introduced the fundamental concept of visual cryptography (VC) in 1994. In that model, the secret image is split into two meaningless shares, allowing the secret to be revealed and recognized by the human eye just by superimposing the two shares. Since then, many scholars have studied the VC problem. To improve the efficiency of transmitting secrets, multi-secret visual cryptography has been proposed to encrypt multiple secret images at the same time. On the other hand, with the reduction in hardware costs, research on XOR-based VC has become popular to address the issue of poor image quality in the recovered image of OR-based visual cryptography, though it requires computing equipment. Scholars also have developed VC schemes utilizing OR-based decryption (equivalent to traditional VC) and XOR-based decryption. These schemes recover secrets without additional hardware (using OR-based decryption) and provide higher-quality images when extra hardware is available (using XOR-based decryption). We propose a visual multi-secret sharing scheme (VMSSS) to encrypt multiple secret images into n (>1) shares. When all shares are collected, all original secret images are decrypted by using the OR or XOR operation.