一种抗投影攻击的矢量空间数据盲水印算法

摘要

The watermarked vector spatial data may be affected by projection transformation and coordinate transformation repeatedly.The existing watermarking algorithm for vector spatial data cannot extract the watermark in most cases under the constraint of unknown data coordinates when the watermark is embedded.As a result,a watermarking algorithm for vector data which can resist projection transformation and coordinate transformation attacks is put forward.The algorithm is constructed according to the characteristics of projection transformation and coordinate transformation for vector data.The watermark embedding scheme transforms the original data into a vector space under WGS84 geographic coordinate system.Then,the watermark is embedded into the WGS84 coordinate space data using DFT domain watermarking algorithm.Finally,the watermarked data was converted from WGS84 coordinate space to the original data coordinates.When detecting the watermark,the data must be converted from the original vector space coordinates to WGS84 coordinate system,and afterwards the watermark can be detected.Experiments results show that the algorithm is robust against projection transformation and coordinate transformation attacks and is also robust against other attacks such as cropping,rotation,and translation.%鉴于含水印矢量空间数据在使用过程中可能会经过多次投影变换或坐标系变换,水印嵌入时的坐标系未知情况下,现有的矢量空间数据水印算法普遍存在不能提取水印信息的问题,提出了一种对坐标系变换和投影变换攻击鲁棒性高的矢量空间数据水印算法.针对矢量空间数据坐标系变换和投影变换的特点,在水印嵌入过程中,首先把原始矢量空间数据变换到WGS84地理坐标系下,然后运用离散傅里叶变换域水印算法,将水印嵌入到WGS84坐标系,最后把含水印的WGS84坐标系空间数据转换到原始数据坐标系.在水印提取时,把矢量空间数据从原坐标系转换到WGS84坐标系后提取水印.试验表明,该算法可有效抵抗坐标系变换和投影变换的攻击,并且对数据的裁剪、旋转、平移等攻击具有较强的鲁棒性.