The Structure Of Visual Cryptography Scheme And Application

With the development of information technology, information security isincreasingly serious, and the field of information security is expanding. However, thetechniques which are based on traditional cryptography require a lot of energy on keystorage, management and distribution. It is clear that these questions cannot meet theneeds of the current national information security. Under the urgent needs of the reality,the visual cryptography has been proposed as a new research direction. It is a specialkind of secret sharing scheme for image encryption. It has the characteristics such as thesimplicity of the secret recovery, high safety and strongly concealment. The participantscan restore the secret image by stacking the sharing images which do not need to masterthe knowledge of cryptography, only need to use the human visual system. In this paper,we have studied several important directions in visual cryptography, and mainly obtainsome results as follows:(1) According to the further study of the traditional threshold visual cryptographyscheme, we deeply study the six research directions of visual cryptography in recentyears that lay the foundation for the next step;(2) Considering the problem of pixel expansion and contrast in visual cryptographyscheme, this paper proposes a color visual cryptography scheme without pixelexpansion which is based on the research of XOR algorithm and combined with theadditive color model and halftone technique;(3) Considering the participants and distributor cheating problem in visualcryptography scheme, this paper proposes a verifiable color visual cryptography schemewhich is based on a trusted third party. This scheme effectively solves the cheatingproblem in visual cryptography scheme;(4) According to the further study of digital watermarking, digital signatures, QRcode and other cryptography technology applications of visual cryptography, we furtherexpand the application range of visual cryptography;(5) This paper proposes a DWT-domain dual watermarking algorithm of colorimage which is based on visual cryptography. Through the simulation experiments, thisalgorithm improves the transparency and robustness of watermarks effectively, andimproves the security of the watermarks.