A distortion free watermark framework for relational databases

In this paper we introduce a distortion free invisible watermarking technique for relational databases. The main idea is to build the watermark after partitioning tuples with actual attribute values. Then, we build hash functions on top of this grouping and get a watermark as a permutation of tuples in the original table. As the ordering of tuples does not affect the original database, this technique is distortion free. Our contribution can be seen as an application to relational databases of software watermarking ideas developed within the Abstract Interpretation framework.