Ideal Contrast Secret Sharing Scheme through Meaningful Shares with Enveloping Digital Watermarking using Bit Plane based (k,n)-VCS

Visual Cryptography Scheme (VCS) is an encryption method that works on human visual system. It encrypts a secret image into n shares and decryption can be done only by stacking k or more share images without any computation. A new secret sharing scheme with meaningful shares using (k,n)-threshold visual cryptography and digital watermarking for grayscale images based on bit plane encoding is proposed in this paper, that encrypts a grayscale secret image in such a way that results of encryption is in the form of shares. Shares do not reflect any information directly, information is scrambled instead. Firstly, an image is decomposed into its bit plane images that generate a binary image at each bit plane. Secondly, the traditional binary secret sharing scheme is used to get the sharing images. Finally, a proposed watermarking technique is used to generate meaningful shares. To decrypt hidden secret image, extract the shares from the cover image and decompose each share into bit planes and then secret grayscale image is reconstructed. This scheme provides a more efficient way to hide images in different meaningful shares. Furthermore, the size of the hidden secret can be recovered by inspecting the blocks in the shares.