On the security of a copyright protection scheme based on visual cryptography

With copyright protection in mind, the robustness property of a new scheme is always one of main concerns. However, to claim robustness of watermarking techniques is meaningful only when the false positive probability is taken into consideration as well as robustness benchmark. In this paper, the security of a robust copyright-protection scheme based on visual cryptography proposed by Lou et al. is analyzed. We show that the false alarm of their scheme is not neglectable. Precisely, it is insecure since the verification watermark can be unreasonably extracted from other unprotected images using the identical secret key by the owner. The main weak design will be proved and shown by means of giving theoretical analysis and conducting some counter experiments.