The Application And Research Of The Digital Watermarking Technique In Certificate Anti-Counterfeit Systems

With the criminal activity of forgery becoming more and more, the credential anti-counterfeiting technology has also rapidly developed recently. At present, the credential anti-counterfeiting technologies mainly based on special techniques and special materials. As a result, it not only increases the certificate of the complexity of the production process of the certificate, but also improves the production cost of certificates. As an ordinary certificate like student ID card or degree certificate, it is not so fit to have a high cost. And once the criminals mastered the technology, the traditional anti-counterfeiting measures will fail and the safety of the documents will get serious threats.In this paper, based on the analysis of the special requirements of the credential anti-counterfeiting, combining with the QR code’s capacity and error correction capability, the author embeds a QR code as a watermark into the photo of the credential.This paper researched and summed up the watermark of printing at home and abroad in recent years. It analyzed the general steps of the digital watermark used in credential anti-counterfeiting systems, and then leaded to the algorithm’s requirements of anti-printing-scanning. It also researched the influence of process of printing and scanning and took some corresponding methods to solve the distortions in the process.And then the author exacted the approximately constant information in the process as characters of the image, which was taken as the zero-watermark. The copyright information was made of the QR code which was come from the information of the credential and the zero-watermark. And the MATLAB was used in the algorithm simulation to verify the feasibility and reliability of the scheme. The experimental results show that:the extracted QR code can be successful decoded after the general attack such as:rotation attack, noise attack, image enhancement or turn dark and general print scanning. And thus the plan is able to achieve the purpose of credential anti-counterfeiting.The innovations of this paper can be divided into the following aspects: First, the analysis of image rotation invariant area, and the watermark is embedded in the area, and combining with the Radon transform to adjust rotation attack, the algorithm has strong robustness in the rotation attack.Second, as the embedded and extracted algorithm is all-known, the author uses digital signatures to protect the text information and picture information of the certificate and to prevent the forgery attack.Third, use the QR code’s high capacity to protect the text and image information of the certificate.And at the same time, because of the QR code’s own error correction performance, the extracted watermark which is a QR code can be successful decoded after some attack. In this way, it really realize the credential anti-counterfeiting.