Design Of Wavelet Domain Electronic Seal System Based On CDMA

Since twenty-first century, the development of electronic government affairs makes a spurt of progress. Along with the growing popularity of e-commerce and e-government, we find that the traditional seal has a lot of inconvenience. Such as it is a waste of paper resources, and easy to peek, easy to lose. What’s more, the circulation of documents uses several days from the beginning to the end and it is time-consuming. The electronic seal comes into being as an inevitable product of the development of modern society. The electronic seal retains the external manifestation of the traditional seal, provides an effective way of secure transmission of documents between the network and ensuring document integrity and authority."Electronic signature law of the People", which comes into effect on April1,2005, mentions that the reliable electronic signature and the handwritten signature or seal has the same legal effect. The electronic seal has been recognized by the law.Therefore, it will be gradually into everyone’s perspective, service for everyone.Electronic seal not only meets the traditional function of the seal, but also solves the contradiction between the traditional seal technology and the modern paperless office in the digital environment, and it is the organic unity between digital signature and seal image. Digital signature technology is the key technology to protect the safety of electronic seal. However, the results of the digital signature vary with different contents of the signed document information or different time signature. And we can not get the fixed graphical information from the digital signature, it can only be applied to electronic documents, could do nothing for ordinary files.In office automation system, we use Microsoft Office Word most of the time. In order to add visualization signatures to Word electronic documents, and help the receiver verify whether the article has been tampered and the identity of the signing person, this paper designs the electronic seal system based on the wavelet domain. The system uses CDMA technology and digital signature technology to combine the seal picture with digital signature, so that the only sign information of users and digital signature information of the seal documents can be embedded into seal picture in the form of watermark. In that case,we can ensure the uniqueness of the seal, the data integrity of the sealed documents and the seal cannot be copied. At the same time, it avoids the security risks of directly attaching signature information to the documents. And the verifier can determine whether a document has been tampered through removing the watermark with corresponding watermark extraction algorithm. This paper focuses on the rationality of the algorithm. After validation of comparison, we use DWT to achieve three level wavelet decomposition of the electronic seal image, and find LH3, HL3and HH3bands from the ten sub-bands generated as the band position. Embedding watermark information into image in the band combined with CDMA technology ensures that the digital watermark has strong robustness and watermark embedding capacity.The software system of electronic seal includes the generation of the common seal picture, watermark embedding system, watermark extraction system, how to embed into the Word as a plug-in and information check.The electronic seal system described in this paper basically achieves that the sender embeds the information of article summary into the seal picture and the receiver extracts the information and verifies the authenticity. But the details of the technology needs further improvement.