基于小波变换的关系数据库水印算法

Relational database watermarking algorithm based on wavelet transformation

为了对关系数据库数据实施版权保护,提出一种基于小波变换的鲁棒盲水印算法.嵌入时先构造主键HASH值的最小非负剩余系对数据分组,然后通过设置各组数据小波变换后"高/低频数据对"奇偶性的异同嵌入信息.提取时统计相应位置数据对的奇偶性异同频度,依据阀值判断而获取嵌入的水印.试验结果表明,水印提取的准确度较高,算法具有较好的隐蔽性、鲁棒性,在数据丢失60%的情况下,仍能较完整的提取出水印信息.

In order to protect copyright of the relational data, a novel and robust watermarking algorithm based on wavelet transformation is proposed in this paper. The algorithm firstly groups the data by constructing a complete residual system which is based on the hash values of the primary keys, and then applies wavelet transformation to the data of each group and embeds one bit in each group by setting parity similarity or difference in a pair of high and low frequency data. When the watermark is extracted, the mark is retrieved from groups by counting the frequencies of similarities and differences of parity pairs at corresponding positions, and comparing with the thresholds. Experiment results show that the algorithm has a relatively high accuracy, a preferable imperceptibility and a good robustness, which allows up to 60% loss of data while almost integral marks can still be extracted.