The Research On Database Watermark Technology

With the development of computer technology and network, there are more and more database applications in network, and it is urgent for the copyright protection of database. So people research the technology of digital watermark to protect the copyright of database.The database has large number of data but little redundancy and it needs some operations normally, so it can't apply the traditional digital watermark technology to database directly. It is require studying the characters of database and watermark technology, developing a watermark mechanism to satisfy copyright protection of database. It is called database watermark technology. It is similar with the multimedia watermark technology;it can embed some information that hard to be wiped off into carrier and it can be extracted correctly in need.Based on current database watermark technology, this paper puts forward a database watermark scheme with real time embedding and implements a prototype of RWRDS. The scheme is component of three processes: watermark generation, embedment and extraction. First of all, it transforms different copyright information to binary stream;the second, according to a cryptographic keyed hash of primary key and attribute, it labels the field with the hash value and groups the data, then embed watermark corresponds to different group data. The embed algorithms is combined single bit with the least significant bit and simulate experiment shows the algorithm takes use of the original data to hide watermark efficiently and takes a minimal influences to data. The last step is to extract watermark base on hash value and take majority vote to decide the watermark bit, and then recover the copyright information.The experiment shows the RWRDS scheme can embed watermark conveniently and resist familiar attacks with high security, and it also can embed real-time online and satisfy the operations of database.