Watermark Technology Research And Application Of Tracing Copyright

The present computer technology accelerates the digitalization of the information and the transmission of information become easier. Meanwhile the security of information became an important question. The encryption system, which was developed from the traditional cryptography theory, resolved some security questions in a certain extent, but presents some other questions. For one of them, copyright protection, scholars brought forward many effective methods, one of which is the watermark technology. As a information hiding technology, the watermark technology is a procedure of secretive hiding watermark information, not modifying datum format and size and not affecting normal usage of datum. The carrier of watermark could be image, text, audio or video file. In the procedure of copyright promulgation, in order to trace the buyer of copyright, scholars introduce watermark technology and create the digital fingerprint, i. e. a copy to a watermark. But, because of the symmetry of normal fingerprintsbased on the normal watermark technology, the evidence accusing the origin of pirates is excusable. The asymmetry fingerprint can well overcome the shortcoming, which is a direction of the copyright protection system.In the paper, my main works are : (1)1 introduced and researched the present watermark technology, discussed some concern theories, e. g. asymmetric decryption, the datum transform, random sequence, correlating, presented the relative deduction and reasoning. (2)1 analysed the shortcoming of the asymmetric fingerprint based on the normal watermark technology and referred the symmetric fingerprint as a resolution. (3)1 brought forward a scheme of asymmetric fingerprint in view of general protocol system and coding. The protocol of tracing copyright is an general frame of asymmetric fingerprint based asymmetry watermark embedding. More, in order to implement the protocols, I present a watermark technology, including some details about the technology and discussions of them. (4) The test of watermark indicates the scheme adapted in the paper satisfy the imperceptibility and robustness up to the requirement of tracing copyright function of fingerprint.The organization of the paper is:The 1st chapter introduced the background and my work about the question in the paper. The 2nd introduced some basic concepts and technology of digital watermark and digital fingerprint. The 3rd chapter introduced a practical question in the procedure of tracing copyrights using asymmetric fingerprint, then analysed the idea of resolution. The 4th chapter introduced some theory and relevant deduction and reasoning. The 5th chapter introduced a general frame of symmetric fingerprint I practiced : the protocol of tracing copyright. The 6th chapter introduced a watermark technology, namedtracing copyright watermark , applying to symmetric fingerprint and its implementation. The 7th chapter presented some test datum and analysis of the tracing copyright watermark. The 8th chapter summarized the paper , suggest some improvement of it and expected the development of symmetric fingerprint.