Research On The Sharing Security Of Vector Geography Data

Vector geographic data, as one of the supporting data for national infrastructure construction and earth science research, plays a pivotal role in the national defense and economic construction. With the growing sharing demands of vector geographic data, the security issues of which has been more and more obvious, such as infringement, piracy, leaks, illegal distribution and use behavior. And the sharing of vector geographic data is seriously blocked. Hence how to use technical means to resolve the contradiction between the sharing of vector geographic data and security is urgent in present.Security issues of vector geographic data are analyzed in this paper. And base on encryption technology, digital watermarking technology, combining with the set mapping, the mathematical theory of non-linear change functions, the key technologies of sharing security issues for vector geographic data is deeply studied. The main research results are as follows:(1) Based on the sharing process of vector geographic data, the security requirements and characteristics of which are expounded. And the function of precision reduction, encryption technology and digital watermarking technology working on protecting vector geographic data in the sharing progress is discussed.(2) Based on analyzing the precision characteristics of vector geographic data, the precision reduction rule and model are implemented. Using the methods of set mapping, a random interference precision method with plus rules for vector geographic data is proposed. By using this strategy, the topology and geometry relations of the vector geographic data remain in a maximum extent, so that the application of data and the data security can both meet demand.(3) By using the characteristics of nonlinear function, a precision reduction model for the vector geographic data based on the multiplication rule is proposed. And this method has been theoretically proved that it could maintain the consistency of the data location. As the continuity and increments of the function, the accuracy can be effectively controlled under the circumstance of keeping vector geographic data in the better topological invariance.(4) By analyzing advantage of modern encryption technology, a strategy of security protection for classified vector geographic data based on AES encryption technology is proposed. The security of vector geographical has been enhanced by the topology rules, and at the same time the availability of vector geographic data is maintained in the local encryption and decryption process. The security service for vector geographic data is also studied based on combining encryption and watermarking.(5) The application model, performance evaluation and algorithm design ideas of the vector geographic data is discussed. According to the demand of solving the multistage copyright protection of vector geographic data, a two-level watermarking model for vector geographic based on bi-directional mapping is proposed, so that the second watermarking would not cover the first one. Moreover this algorism achieved the goal that to maintain robustness of the single-level digital watermarking algorithm(6) A multi-level watermarking algorithm is proposed so that the problem of embedding more than two users into the vector geographic data is solved. By using the method of resynthesizing the segmented watermark information, the level has been increased; the proposed algorithm enhanced the copyright protection for vector geographic data.(7) Furthermore, a quad-tree dynamic block multi-level watermarking algorithm is proposed to solve the unpredictability of the data distribution quantity. By using this algorithm, the watermark information can be dynamically added. So that the constraints of pre-arranging the quantity of the data distribution is overcome and the multi-level watermark technology could be more flexible.