【作者】 钟征燕；

【导师】 郭燕慧；

【作者基本信息】 北京邮电大学 ， 信息安全， 2013， 硕士

【摘要】 互联网技术日新月异,极大的推动了网络出版行业的快速发展。网上交易和传播的电子产品越来越多,随之而来的盗版和非法传播现象也越来越严重,数字版权保护问题成为了网络出版行业发展的瓶颈。而数字水印技术的提出,为解决数字版权保护问题提供了新思路。目前在网络出版的电子文档中,PDF格式的文档居多,因而研究针对PDF文档的数字水印技术在数字版权保护领域具有重要的应用价值。本文通过分析PDF文档的结构及相关数字水印算法,针对现有一些水印嵌入算法存在的不足,提出了基于PDF文档结构和基于PDF文档ID的两种数字水印算法。其中基于PDF文档结构的数字水印算法利用行末标识符不会在文档中显示的特性,通过等量替换PDF文档中具有固定格式的交叉引用表的行末标识符,来实现水印信息的间接嵌入。而基于PDF文档ID的数字水印算法则是通过替换ID的第一组字符串来实现水印信息的嵌入。由于PDF文档的ID具有唯一不变性,因而嵌入的水印信息不易被去除,具备很好的鲁棒性。实验结果表明,上述算法水印容量都能满足数字版权保护的要求,隐蔽性好,具有较好的实用性。在上述算法研究成果的基础上,设计并实现了一个文本水印系统,实现电子文档的版权信息嵌入和提取,并对系统的性能进行了测试和分析。该系统在网络出版行业具有广阔的应用前景及实用价值。更多还原

【Abstract】 The Internet technology is developing rapidly, which greatly promotes the development of network publishing industry. More and more electronic products are traded and propagated online, and piracy and illegal propagation phenomenon is more and more serious, Digital copyright protection problems become a bottleneck of the network publishing industry development. And the digital watermarking technology provides a new thought to solve the digital copyright protection problem. At present, most of the electronic documents published in network are PDF documents, therefore, the study of digital watermarking technology according to PDF documents will have an important application value in the field of digital copyright protection.According to the shortages of some existing watermark embedding algorithms, through analysis the structure of PDF documents and its related digital watermarking algorithm, this paper proposed two kinds of digital watermarking algorithm, one is based on PDF document structure and the other is based on PDF document ID. As to the digital watermarking algorithm based on PDF document structure, considering the characteristics that end-of-line marker cannot be showed in the document, this algorithm manages to embed watermark through replacing end-of-line markers of the cross-reference table with a fixed format. And the watermarking algorithm based on PDF document ID manages to embed watermark through replacing the first group string of ID. Due to the PDF document ID is sole and invariant, the embedded watermark is not easy to be removed, thus its robustness is good. The experimental results show that, the proposed algorithms can not only reach the standard of watermark capacity required by digital copyright protection, but have good concealment and practical applicability as well.Based on the above algorithm research achievements, this paper designs and implements a text watermarking system, which can embed the copyright information to the electronic document, meanwhile extract the copyright information from it. And the performance of the system is. tested and analyzed. This system has a broad application prospect and practical value in the network publishing industry.更多还原