摘要:关系数据可逆水印技术是保护数据版权的方法之一.它克服了传统的关系数据数字水印技术的缺点，不仅可以声明版权，而且可以恢复原始数据.现有方法在恢复原始数据时不能控制数据恢复的程度，无法调节数据的可用性.提出了一种分级可逆的关系数据水印方案，定义了数据质量等级来反映水印嵌入对数据可用性的影响，设计了用于实现分级可逆水印的分区嵌入、等级检测、水印检测以及等级提升算法.数据所有者在数据分发前预先设定若干数据质量等级，以数据分区为单位嵌入水印.每个数据分区使用独立的密钥控制水印信息的位置和取值.如果数据使用者希望提升当前数据的可用性，可向数据所有者申请或购买相关密钥，提升当前数据的数据质量等级.对于任意数据质量等级的数据，其中的数字水印均可用于证明版权.采用分区的辅助数据，实现了灵活的水印逆操作.设计了有效的哈希表冲突解决方法，降低了计算和存储开销，提高了该方案的实用性.实验结果显示，方案具有良好的计算性能以及鲁棒性，可满足现实应用场景的需求.



Abstract:Reversible watermarking technique for relational data is intended to protect the copyright. It overcomes the shortcomings of traditional watermarking techniques. It can not only claim the copyright of data, but also recover the original data from the watermarked copy. However, existing reversible watermarking schemes for relational data cannot control the extent of data recovery. Aiming at this problem, a graded reversible watermarking scheme for relational data is proposed in the study. Data quality grade is defined to depict the impact of watermark embedding on the usability of data. Watermark embedding, grade detection, watermark detection, and grade enhancement algorithms are designed to achieve graded reversibility of watermark. Before distributing the data, the data owner can predefine several data quality grades, then embed the watermark into data partitions. A unique key is used in each data partition to control the position and value of the watermark information. If data users are not satisfied with the usability of data, they can require or purchase relevant keys from the owner to upgrade the data quality grade. The watermark in relational data with any data quality grade is sufficient to prove the copyright. Flexible watermark reversion is achieved via partitioned auxiliary data design. A more practical mechanism is devised to efficiently handle the hash table collision, which reduces both computational and storage overhead. Experiments on algorithms and watermark show that the proposed scheme is feasible and robust.



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