Text format based relational database watermarking for non-numeric data

The digital information revolution and increasing of outsourced data in many organizations caused significant changes in the global society where digital data are available everywhere with free of cost. Proving ownership rights of outsourced relational databases is a crucial issue in today internet-based application environments and in many content distribution applications. In the past few years, a large number of techniques have been proposed for right protection of numeric data. In this paper, a new relational database watermarking method for non-numeric multi words data is proposed. A mark is embedded by horizontally shifting the location of a word within selected attribute of selected tuples; a word is displaced right or left unmoved depending on watermark bit. The location where the mark to be inserted is determined by the Levenshtein Distance between two successive words within an attribute. Our method is effective as it is robust against different forms of malicious attacks and it is blind as it does not require the original database in order to extract the embedded watermark.