Research On Integrity Authentication Of Vector Map Base On Digital Watermark

With the rapid development of information processing technology and surveyingtechnology, digital vector maps have been widely applied in geographical informationsystems, digital city and intelligent transport systems. Digital maps can be easily copied anddisseminated, which greatly facilitates people’s daily life and work. However, illegaltampering and spread of vector maps will seriously undermine the map owners’ interests.Therefore, the research on vector map’s integrity authentication mechanisms is very importantto curb the illegal tampering and spread, and it has become hot in today’s information securityresearch. This paper mainly discuss as follows several contents.Firstly, this paper provides a method of generating authentication-watermark by studyingthe traditional authentication technology. Based on traditional thought, digital vector map ishashed as a binary stream,and computed to get the summary of the map, the summary isdefined as authentication-watermark to identificate the map. Based on the file system filterdriver technology, the watermark is embed in the coordinate file’s header file in kernel level.Secondly, this paper provides a method of generating locate-watermark by researchingthe coordinate structure. According to the coordinate structure, fifty polylines are dealed as aprocessing unit, the summary of the unit is computed and converted into binary streams aslocate-watermark. The watermark is embed into the coordinate file’s coordinates by enlargingcoordinates in kenel level.Thirdly, this paper provides a method of generating recover-watermark by studing vectordata’s compression method and relationship between coordinates. A polyline is used as aprocessing unit, the double differences between coordinates are computed by coordinatestructure, then changed into integer,subtracted by the average of corresponding data block, atlast, the data are compressed by BZIP2function. The recover-watermark is embed at theheader of coordinate file after the identify of watermark and the length of recover-watermarkin kenel level.Finally, this paper provides a integrity authentication method by studing vector map’sauthentication method. For the integrity authentication request, the authentication-watermarkis extracted in kernel level. The authentication-watermark of the detected file is computed andcompared with the extracted watermark to determine whether the map has been tampered. If the two watermarks are the same, then authentication will be successful, otherwise it fails.The locate-watermark is extracted from the coordinates, the tampered processing unit of fiftypolylines is located. The recover-watermark is extracted and calculated the originalcoordinates, the tampered coordinates are restored by original coordinates.