A novel visual cryptography scheme based on substitution cipher

Security of information communication through open channels has been the prime concern during the last few decades. Apart from many conventional cryptographic schemes, visual cryptographic techniques have also been in use for data and information security. Visual Cryptography is basically a cryptographic method in which decryption is performed by human visual system. In this paper, we present a novel visual cryptography scheme based on a substitution cipher and random grid. The scheme uses two-fold encryption. In the first fold of encryption, Caeser cipher is used to encrypt the image row wise and then column wise using a key of the size equal to the greatest common devisor of the number of rows and columns in the secret image. Then a random matrix is generated and the transformed secret image is XORed with this random matrix to enhance the security. The scheme is shown to be secure and decryption is also lossless.