General Construction for Extended Visual Cryptography Scheme Using QR Codes

摘要

This article describes how a visual cryptography scheme, with one prominent feature—decrypting simply, has attracted much research attention since it was first proposed. However, meaningless shares remain a continuing challenge in the development of VCS. In this article, an extended visual cryptography scheme (EVCS) based on XOR operation is proposed, in which QR codes are utilized as the cover images of shares. By designation, all the shares generated in the scheme can be decoded by standard QR code readers with specific meaning. In addition, to achieve high sharing efficiency, a method of simultaneously sharing a secret QR code among multiple subsets is presented. Also, sufficient and necessary conditions of the method are analyzed with an integer programming model, providing a general construction approach for EVCS under arbitrary access structures.