【作者】 胡斌；

【导师】 施荣华；

【作者基本信息】 中南大学 ， 信号与信息处理， 2007， 硕士

【摘要】 随着信息化程度的提高，关系数据库的版权保护问题变得十分重要。关系数据库数字水印作为信息隐藏技术研究领域的重要分支，能够在原始数据库中嵌入版权认证信息，并且不破坏数据库的使用价值或商用价值。因此，关系数据库数字水印技术在版权保护方面的应用具有较高的现实意义和理论意义。本文收集和分析了近年来国内外数字水印方面的文献，在现有关系型数据库水印算法进行研究的基础上，提出了一种基于密钥分存思想的关系数据库水印技术，该算法通过对水印信息的分存，以及最低有效位的修改，使水印信息分布得更“广泛”，而且原始水印的恢复只须部分子水印即可，能明显提高水印的鲁棒性。接着提出了一种使用图像作为水印的关系数据库水印算法。在算法中引入了三元组的思想，在一个字段值中就可嵌入3个bit，极大地扩大了水印信息的容量。为了进一步拓展研究应用领域，本文设计了一种基于非数值型字段的关系数据库水印算法。该算法最小化了在嵌入水印时需修改的数据量，并且允许数据的拥有者自己定义一个相似函数选择元素进行水印嵌入。最后，本文设计开发了水印系统软件，将本文提出的算法应用于水印系统中，实现了关系数据库中数字水印信息的嵌入和提取。更多还原

【Abstract】 With the development of information technology, protection of copyright for relational database has been more and more important. As an important branch of information hiding technology, watermarking based on relational database can embed copyright information into the original database, without destroying the usability of database. Therefore, studying on the watermarking based on relational database has great significance in terms of both theory and application.On the basis of researching and improving the current watermarking algorithms of relational database, a new algorithm for relational database based on Blakley secret sharing scheme is proposed in this paper. By secret sharing, the watermarking information is distributed more far-flung, and only part content of watermarking is needed when recovering the watermarking. This algorithm can improve the robustness.The paper presents a database watermarking method by using image. In this method, three-bit group idea is introduced, which can imbed 3 bit in every element’s value.In order to broaden the application fields, a new watermarking method for protecting non-numerical databases is designed in this paper. The proposed watermarking system allows the data owner to define a similarity function in order to reduce the distortion caused by watermark embedding and, at the same time, reduce the number of element modifications needed by the embedding process.Finally, this paper develops software of watermarking system, applies the algorithm carried out in this paper into watermark system and realizes the embedding and recovering of watermark information in relational database.更多还原