| Summary: Protecting database integrity has become a matter of increasing importance nowadays as accessing information is getting easier. Basically, different perspectives as distortion based and distortion free watermarking has been developed for the solution of this issue.
In this study, two different distortion free zero watermarking schemes are investigated and consequently, a new zero watermarking scheme is proposed for relational databases. While DCT based watermarking proposed in this study, has been used in the field of image watermarking, it has not been used in watermarking of relational databases, which makes the proposed method a novel database watermarking method. The aim of the proposed watermarking method is to identify whether the integrity of the database in question maintained or not by identifying the changes as a result of attacks to the watermarked data. The method divides database into groups and with these groups the method obtains sub-groups which have the row count which is half of attribute count. With the obtained matrix, watermark information is generated for the related group by calculating DCT coefficients. After calculating DCT coefficients for all groups, group watermarks concatenate and a watermark is generated for the database. Experimental results show that methods proposed as temporal, detection range and watermark size present improvements.
Keywords: Distortion free watermarking, Fragile zero watermarking, Relational databases watermarking, Database integrity checking, Discrete cosine transform, Digital watermarking, Distortion detection.
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