基于二维空间元素匹配的数据库水印算法

针对现有数据库水印算法对原始数据修改量大、水印信息隐蔽性差的问题，提出一种基于二维空间元素匹配的关系数据库鲁棒水印算法。算法选取数据库主键的Hash值作为元组的定位空间，选取数值属性冗余位作为元组的数据空间，构建了一个二维空间。通过调整二维空间对应元素的奇偶性嵌入水印信息。实验中嵌入水印前后载体数据均值变化0.5296×10^(-2)%，方差变化0.6509×10^(-4)%，表明该算法对原始数据修改量小，水印隐蔽性好，鲁棒性强。

Database watermarking algorithm based on parity modulation in two-dimension space

To decrease the modification of original data during the process of database watermarking,and to make watermark information more secretly,an algorithm based on parity modulation in two-dimensional space was proposed.One dimension was made up of primary keys’ Hash values,the other was made up of numeric attributes’ redundant bits.Watermark information was embedded by modulating the parity of Hash values and redundant bits.After watermarking,the modification of data average was 0.529 6×10-2%,and the modification of data variance was 0.650 9×10-4%.The experimental results indicate that the modification amount of original data is reduced and this algorithm is efficient and robust.