Natural language letter based visual cryptography scheme

Naor and Shamir proposed the notion of a (k,n) visual cryptography scheme (VCS), which allows k or more stacked transparent share images to reveal a secret image. It can be used without prerequisite knowledge of cryptography or complex computations. In these schemes, no information about the secret can be obtained from fewer than k shares. Previous VCSs use black and white subpixels to create share images. In this paper, we present a letter-based VCS (LVCS) where pixels are replaced by letters for the share images. Shares can now be constructed using meaningful data as subterfuge all while carrying secret data in plain sight, and an adversary will not recognize them as containing secrets. We prove that the proposed (k,n)-LVCS satisfies contrast and security conditions and secret information may be reconstructed by any k shares but with less than k shares reveal nothing.