Adaptive visual cryptography scheme design based on QR codes

Abstract

QR code based visual encryption schemes are still relatively rare, and the existing schemes are mainly implemented by averaging grayscale maps. They become distorted when recovering complex secret images. In this paper, we propose a visual cryptography scheme based on QR codes. We use two adaptive schemes to improve the distortion problem in secret image recovery. The algorithm for generating the QR code shared matrix is improved, and the secret image can be restored quickly. This scheme could ensure the uniform distribution of secret vectors. Meanwhile individual shared QR codes would never reveal any secret information. The proposed algorithm reduces the space consumed by the secret vector and the probability of falling prey to illegal attacks. Compared with other schemes, the secret image recovered via the proposed method is clearer and the scheme is suitable for scenarios in which the secret images are more complex, as it yields better security and practicality.