Study Of Extended Visual Cryptography Scheme

With the rapid development of computer network and electronic commerce, information security problem is increasingly serious. Information security is based on cryptography. But traditional cryptography has a problem of key management. Visual cryptography is produced which as a new research direction. It has been widely used in terms of secret sharing and information hiding. It is for image encryption of a special kind of secret sharing scheme, has the characteristics such as high safety, strongly concealment. The participants can restore the secret image by stacking the sharing images which do not need to master the knowledge of cryptography, only need to use the human visual system. In recent years, with the development of visual cryptography, the study of visual cryptography is focused on parameter optimization, the color visual cryptography scheme, visual cryptography of the meaningful sharing image, multi-secret sharing visual cryptography and the application of visual cryptography. In this paper, we have studied several important directions in extended visual cryptography scheme, and the dissertation obtains main results as follows:(1) The sharing images of visual cryptography scheme is chaotic random noise image, it is easy to cause the attacker’s suspicion. This paper proposed a color visual cryptography scheme with meaningful shares. At the same time, the recovered secret image without any pixel expansion.(2) The traditional visual cryptography can only hide or restore an image. It will cause the waste of resources. In this paper, we construct a visual cryptography which can hide and recover many pictures.(3) This paper proposes a visual cryptography for hiding some information but displaying others. By hiding some important information, it extended the application of visual cryptography.