Steganography Authenticated Quadrant Stacked Multiple Image Visual Cryptography Scheme with Perfect Reconstruction

Visual Cryptography Scheme (VCS) is an image based encryption procedure which encodes the secret image into multiple binary images called shares. The shares are random meaningless patterns of identical number of 0’s and 1’s, and hence the shares do not expose the secret. In conventional VCS, shares are printed over transparencies or transmitted digitally to the receiver. During decryption, shares are overlaid to recover the secret which can be recognizable by Human Visual System (HVS) devoid of any processing. However the deciphered secret image will not be a perfect reconstruction in conventional VCS and it encounters contrast loss. "Two-in-One Image Secret Sharing Scheme" (TiOISSS) combines VCS that can decipher the ambiguous secret recognizable through HVS during the first phase and “Polynomial Image Secret Sharing Scheme” (PISSS) to achieve perfect reconstruction in the second phase. TiOISSS is implemented for single secret in most works. In the proposed scheme, TiOISSS is extended to share multiple secrets, in terms of four secrets per share, by stacking the shares over the four quadrants, termed as "Two-in-One Multiple Image Secret Sharing Scheme (TiOMISSS)". The number of secrets can be extrapolated as one share for every four secrets. Steganography data is encoded into the shares for authentication. The efficiency of the scheme is assessed using metrics PSNR and SSIM. The scheme results in better quality with infinite PSNR and SSIM value of 1 due to perfect reconstruction.