The Research Of Collusion Attack And Coding On Digital Fingerprinting For Images

The rapid development of communication technology makes the transmission of digital products great convenience, but meanwhile we are confronted with the growing problem of copyright dispute. How to protect the copyright of digital products efficiently has become a crucial issue that call for immediate solution in this information age. Because traditional encryption technique can't constraint users' illegal behavior of re-distribution, tracing the pirates becomes an alternative method to protect copyright. As a new kind of technology, digital fingerprinting can effectively prevent users from illegally use of digital products by embedding an information sequence to digit copy which can identify the subscriber uniquely.The current research in the field of digital fingerprinting includes two aspects: the design of fingerprinting scheme and the research of specific fingerprinting attack method. Focusing on these two aspects of research, systematical study has been carried out. The main work and achievements are as follows:(1) Aiming at orthogonal fingerprinting scheme, we propose a new collusion attack method. In this method, the maximum value, the minimum value and the average value are chosen from every position of the fingerprints. A new illegally copy is built by the sum of maximum value and minimum value subtracting their average value. The fingerprints are modified from linear attack and nonlinear attack. The result shows that our method can make better attack performance under the same perceptual condition.(2) We propose a hybrid coding method based on orthogonal coding and CFF (Cover Free Family) coding. In our method, we first generates the orthogonal codes and CFF codes with small parameters respectively, then expands every position of orthogonal code into the dimension of CFF code, and then embeds CFF code into orthogonal code, finally the new fingerprinting code is generated. Our method has simple structure of encoding and the encoding efficiency is certainly improved. More over, it has excellent performance of anti-collusion.