Tagged Visual Cryptography

This letter presents a method for implementing visual cryptography (VC) in which an additional tag is attached to each generated share. The proposed ( t , n ), 2 ≤ t ≤ n tagged visual cryptography (TVC) scheme works like a traditional VC scheme does, where the original image is encoded in n shares in such a way that the secret can be revealed by superimposing any t or more shares, but knowledge of less than t shares gets no secret information. A notable characteristic of TVC is that an extra tag can be revealed by folding up each share, which provides users with supplementary information such as augmented message or distinguishable patterns to identify the shares. The tagging property can easily be applied to any reported VC scheme to endow the generated shares with more capabilities. Construction methods and simulation results of the proposed ( t , n ) TVC based on conventional matrix-based VC and probabilistic-VC are illustrated in the letter.