Design And Realization Of A Watermarking Software For Tamper Localization

Today, vector maps have become the basic data of Geographical Information Systems. These data have widely applied in the field of the national economy. They have great economic value. Using the network and geographic information processing tools, these data can easily be illegal tampered and disseminated. This may make producers and publishers of geographical information suffer significant losses. Therefore, how to protect the authenticity and integrity of vector map data is an urgent problem to address. As a technique for authenticating integrity, fragile watermarking has become a research hotspot.According to the characteristics of vector maps, a vector map fragile watermarking algorithm for tamper localization has been proposed in this paper. This algorithm consists of two parts: watermark embedding and watermark verification. In the watermark embedding phase, the vector map is first divided into blocks. Then, an authentication watermark is generated for each block and embedded into the block itself using digit replacement. In the watermark verification phase, after block division, an authentication watermark is first extracted. After that, a new authentication watermark is generated. Whether the block is tampered can be justified by comparing the extracted watermark and the generated watermark. After verifying the integrity of all the blocks, tampered blocks can be located.Based on the proposed vector map fragile watermarking algorithm for tamper localization, a vector map fragile watermarking software for tamper localization has been realized on the Windows platform with Visual Studio 6.0. This software is programmed using VC++ and the MapObjects component. This software can not only authenticate the integrity of the vector map, but also locate tampered data. Thus, integrity authentication and tamper localization problems of vector maps have been solved.