Cheating prevention in visual cryptography.
Visual cryptography (VC) is a method of encrypting a secret image into shares such that stacking a sufficient number of shares reveals the secret image. Shares are usually presented in transparencies. Each participant holds a transparency. Most of the previous research work on VC focuses on improving two parameters: pixel expansion and contrast. In this paper, we studied the cheating problem in VC and extended VC. We considered the attacks of malicious adversaries who may deviate from the scheme in any way. We presented three cheating methods and applied them on attacking existent VC or extended VC schemes. We improved one cheat-preventing scheme. We proposed a generic method that converts a VCS to another VCS that has the property of cheating prevention. The overhead of the conversion is near optimal in both contrast degression and pixel expansion.
Hu
Chih-Ming
CM
Department of Computer Science, National Chiao-Tung University, Hsinchu, Taiwan 30050, R.O.C. andyhu@cs.nctu.edu.tw
Tzeng
Wen-Guey
WG
D000465:Algorithms; D003196:Computer Graphics; D016494:Computer Security; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D016247:Information Storage and Retrieval / Q000379:methods*; D010364:Pattern Recognition, Visual