Research Of Copyright Protection And Integrity Authentication For Relational Database Based On Digital Watermarking

With the extensively using of relational database, the problems that its content faces is copyright protection as to multimedia data. Today, techoologies of database contents protection are mostly implemented via cryptography. But when the encrypted data are decrypted, the cryptography loses its protective function for database contents. The digital signature technology based cryptography authenticates the integrity of database contents by adding redundant verification message, which can be removed due to being separated from the sheltered database. To overcome shortcomings mentioned above, a novel solution for database contents protection based on database watermarking is proposed in this thesis. Database watermarking, which embeds implicit and un-removable marks in database, reaches the aim of protecting the database copyright and verifying the integrity of the data contents.without damaging the availability of database content. The main work are as the followings:1. The definition of database watermarking is presented, the main properties and classify method of database watermark are analyzed, and the application areas are concluded. The basic theory of database watermarking technique are explained, as well as their special features and implement methods are summarized. Common types of attacks towards database watermark are listed, meanwhile, the preventive methods against them are proposed.2. A novel database watermarking algorithm for protecting database copyright which can effectively detect and correct false watermarks is proposed. Using BCH/CRC mixed code combined with triple compression theory, by using image, which has more information, as digital watermark source, the quality of extracted digital image watermark is improved. By introducing a trusted center, the additive attack and invertibility attack are prevented. Finally, a judgment formula for image similarity as objective evaluation standard is proposed. The similarity is a judgement database copyright basis for trusted center. The simulation results show that the algorithm has preferable robustness and can effectively resist all kinds of subset attacks.3. A digital watermarking algorithm for authenticating the database integrity is proposed. Based on the fragile watermarking technique, it uses support vector machine to find the optimal predicting function by exploiting the correlation between the given attribute samples. Using trained support vector regression (SVR) function to distribute the digital watermarks over the particular numeric attributes to achieve embedding and detect watermarks by the same SVR predicting function. The simulation results show that the modifications can be detected and localized effectively.