A master share (2, n) XOR based visual cryptography scheme by random grids

The rapid growth of internet applications and network users has made the processing of digital images via internet highly vulnerable. Existing random grid based visual cryptography schemes (RG-VCS) like any other visual cryptography schemes aim at imparting perfect secrecy and fast decryption without any complex computation. One among the several techniques in visual cryptography is the (2,n) RG-VCS which creates n shares with equal weightage and any of two shares out of n can be combined to recover the original image. The drawback of the existing system is that an attacker can recover the original image if he /she obtain any of the two shares created. The proposed system improves the security of (2, n) RG-VCS by incorporating the concept of a master share. The concept of a master share is introduced in such a way that recovery of the original image is possible if and only if one among the two shares combined is the master share. Decryption using any two shares from the remaining n-1 shares other than the master (i.e. client shares) reveals nothing. XOR-based decryption is implemented here as it seems to be a perfect candidate for (2, n) schemes which enhance the image quality of the recovered secret and solving alignment problems in visual cryptographic systems. There by the proposed work implemented a two-tier priority share model enhancing the confidentiality of visual cryptographic applications. Further, sufficient theoretical proofs are provided for the correctness of the implementation.