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Database Watermarking Scheme Based on Clustering with Size Constraint

The improved fuzzy C-means clustering algorithm is used in the process of selecting data to embed watermark. Firstly, aiming at the problem of unstable data size in the traditional fuzzy C-means clustering in the clustering results, the fuzzy C-means clustering algorithm was optimized. Moreover, the data category was further determined on basis of the addition conditional constraints to the clustering. Each tuple of the database can be preliminarily clustered due to the introduced algorithm for database watermark. Then, in each category, the user can select one or several types of data utilized the key control to embed into the watermark. Before embedding the watermark, the proportion parameter is set according to the sparse degree of the watermark, which reflects the principle that the user controls the copyright.