An efficient authentication mechanism for (2,2)-visual cryptography scheme

Visual cryptography (VC) is often used in secret communications between two different sides. The benefit of visual cryptography is that the decryption procedure is without any computations. In the past schemes, they focused on the quality of decoded images and the problem of pixel expansion, but rarely concerned on the authentication issue. The authentication mechanism can be used to verify whether the decrypted image is valid. This paper proposed two authentication mechanisms, namely Scheme-1 and Scheme-2, for (2,2)-visual secret sharing (VSS) with pixel expansion and that with no pixel expansion, respectively. The experiments provide the positive data to confirm the feasibility of the proposed schemes.