基于中国剩余定理的GIS数字水印算法

利用数字水印技术对数据进行保护是一种行之有效的方法，但目前提出的许多算法都是针对多媒体数据的。为了将该技术应用于地理信息系统(GIS)数据保护，首先介绍了数字水印的基本体系，并分析了GIS数据的特点，然后利用基于中国剩余定理的数字水印算法，构造了适用于GIS数据的水印嵌入和提取的方法，以用于实现GIS数据的版权标识和篡改提示。该算法符合Asmuth—Bloom体系，它的优点在于可以根据部分数据恢复出水印信息，其不仅有较好的抗攻击能力，而且在恢复时不需要原水印信息。由于该算法是基于点的坐标来进行水印的嵌入。因此在GIS数据中有较好的推广价值，其不仅适用于关系型数据库，且可以应用到三角网格模型中。

Use Digital Watermarking to Protect GIS Data by Chinese Remaindering

Along with the popularization of Internet and the development of multimedia techniques, internet has become a main way for information communication. People can get a lot of information through the Internet, such as text, image, graphics, audio and video etc. Unfortunately however: internet and multimedia also afford virtually unprecedented opportunities to pirate copyrighted material. This risk is same to the distribution of GIS data through internet. As a result, digital Watermarking has been presented as an efficiently solution to copyright protection. Dozens of schemes and algorithms have been proposed, but most of those are for multimedia data. In this paper, a new watermarking method is proposed for the protection of GIS data. This approach applies the Chinese Remaindering to construct embedding watermarking in GIS data. The influence of embedding process on GIS data would ignore under the lower measurement precision. It can be used as tamper proof and authentication of GIS data .This algorithm accord with Asmuth-Bloom system, so we can extract watermarking use only a part of GIS data. The extraction process doesn't need the original watermarking, because the embedding procedure is based on the states that a positive integer is uniquely specified by its remainder modulo relatively prime integers. The algorithm bases on the coordinate of the points, so it can be widely used in GIS data protection such as relation database, as well as triangular mesh. The results show that the algorithm can work well. Finally, some open problem is discussed.