The Research Of Database Digital Watermark

The digital watermark technology is an information security technology, which is developed last ten years. As an effectively complemental way for traditional encryption means, with the development of information, high attention has been given to the digital watermark technology by international corporations and the academic community.This technology first is used in image, and then expended in voice, video and other digital media. In recent year, with the development of relational database, the digital watermark technology for databases, which embeds watermark in relational database, has become popular. However, the digital watermark technology for databases is so difficult that research on it improves slowly. How to enlarge the redundant space, improve the robustness of the watermark are always the focuses of the research. In this paper, in-depth research has been done on these focuses.The main research content and result are as follows:In relational databases, every field has a certain value, so the redundant space is small. In this paper, the watermark algorithm for databases based on the number of effective bits is proposed, which is focused on how to enlarge the redundant space. A few errors in the fields with long effective bits have been introduced to enlarge the redundant space for databases, without destroying the usefulness of the database.As the particularity of relational database, watermark for databases requests much more than for multimedia on robustness. A new watermark technology for databases based on Chinese Remainder theory is proposed. When recovering watermark information, only part content of the database is needed. The experiments results show that the safety and robustness are improved. Even if the attacker knows the embedded algorithm, only the shared watermark information can be got, and the original watermark can't be recovered.Watermark research for databases based on the Asmuth-bloom scheme. If the sharing secret algorithm based on Chinese remainder theorem is expanded by database watermark, full watermark information can not only be recovered only with a part of watermark, but also the data for watermark can be reduced, moreover the performance can be improved significantly.Watermark technology for databases, which are based on the number of the...