Application And Research Of Visual Cryptography In Certificate Anti-Counterfeit Systems

With the rapid development of information technology, the use of high-tech digital equipment for illegal forgery of activities is also rampant. How to protect the copyright of digital works has the important significance and the extensive application value, especially to the document security has the important practical significance. The traditional anti-counterfeiting means is too expensive; the new anti-counterfeiting technology is not mature. How to improve the security performance is still the problem that the documents need to be solved in the certificate security field. Visual cryptography is a new method in the field of information hiding, and it is widely used in the field of image processing. This dissertation will use the visual cryptography for the security of documents, and propose a new scheme for the security of documents.According to the drawbacks of high costs of the traditional anti-counterfeiting methods, the dissertation puts forward a kind of method based on visual cryptography and QR codes. Firstly, the dissertation uses the QR code generator to generate important information of certificates into QR code. Secondly, visual cryptography was applied to share the secrete information of the data and error correction keys part of QR code into several sharing images. Lastly, the dissertation prints the sharing images around the certificates.In view of the existing digital watermarking technology in the application of credential anti-counterfeiting of embedding capacity and watermark robustness, security is not high proposed a zero watermarking algorithm based on visual cryptography and matrix spectral norm against printing and scanning. On the one hand, the algorithm is the pictures of documents in the two-dimensional wavelet transform, then select low-frequency sub-band part of block, computing each block matrix spectral norm, according to the comparison of each block of spectrum numerical fan and spectral norm mean size of all blocks to generate a feature diagram. On the other hand, with QR code encoder generate QR code, watermark, using visual cryptography techniques combined with the watermarking graph and feature graph, generated two share, will be in a private share as the zero watermarking is saved to the zero watermark information database.The experimental results show that the security scheme of the ID card based on the visual cryptography and QR code is of high security, carrying information capacity and so on. The conventional noise, small angle rotation, shears and scaling has good resistance, but the robustness of the print scan attack is poor. Anti print scan zero watermark algorithms based on visual cryptography and matrix spectral norm, can compensate the shortage of the scheme, and can resist the attack of one and two time print scan effectively. Compared with the pure digital watermarking, the scheme combines the visual cryptography and QR code, and has higher security and robustness. From the quantitative point of view, the error rate is within 10%, and the secret information can be detected accurately in the anti-print scan algorithm.