Research Of Visual Cryptography And Its Application

With the development of computer networks and e-commerce, the field ofinformation security is facing enormous challenges and opportunities. As a newresearch field of information security, Visual Cryptography Scheme (VCS) is theencryption technology for image and has lots of advantages. For example, its process ofencryption and decryption are both simply and with good concealment, moreover, itprovides unconditional security. Compared with the traditional secret sharing schemes,Visual Cryptography Scheme is that, the decryption of the secret image requiresdifferent participants stack of their share images, similar to the one time pad, and theprocess of decryption requires neither cryptography knowledge nor complexcomputation. It mainly applied in high security areas. This dissertation investigates thevisual cryptography technology, with design and application directions and is to proposesafer and high efficient visual cryptography schemes. The dissertation obtains mainresults as follows:（1）The traditional visual cryptography is use of the human visual system torecover the secret decryption, the way to recovery the secret image is simple, but thequality of the recovery image is not ideal. In a computer environment, VisualCryptography is a kind of image encryption technology, with large information capacityand more flexible form of secret information. This dissertation investigates the visualcryptography technology, with emphasis six important research directions andundertook concrete analysis.（2）Visual Cryptography is the same as other secret sharing schemes, which alsohas the problem of deception. The cheater can destroy the recovery of secret image orgain secret information by cheating through making a counterfeit of share images. Inthis paper, in order to resolve the problem of deception, we proposed a verifiable visualcryptography scheme can ensure that the secret image can be visually revealed correctly.This scheme can test and verify the accuracy and truthfulness of every share image,which is simple to decrypt and without any pixel expansion.（3）QR code is widely used in Electronic ticketing which belongs to one of thetwo-dimensional code. Through investigate the application of visual cryptography，wefound that QR code had divulged personal information. In order to solve the securityissues of protected information of QR Code, we find the security problem we introducevisual cryptography technology, the safety and reliability of QR Code has been improved. A (2,2) VCS with XOR algorithm what used in this paper is simple to decryptand the achieved shares are meaningful without any pixel expansion．（4）In view of the traditional visual cryptography scheme is based on the "OR"algorithm, it has some disadvantages like the large expansion of recovered secret imagepixel and the poor of visual quality. We present a method based on “XOR” VisualCryptography Scheme which use of electronic equipment to decrypt. The recoverysecret image without any pixel expansion and does not change the original imagequality.At last, we conclude the results of this paper and give the prospects of furtherresearch.