Research On Bandwidth-efficiency Of Digital Fingerprinting System

Digital fingerprinting is an effective measure for digigal copyright protecting. It embeds a unique ID only corresponding with the right user into his/her copy, which can be extracted to identify the culprits when an unauthorized leak is found. With more and more digital products applying fingerprints, bandwidth-efficient distribution of digital fingerprinting system is crucial. Bandwidth-efficiency means distributing different data of fingerprinted copies to different clients with less bandwidth. Based on the security of fingerprint embedding, this paper focus on the issue of bandwidth-efficient distribution of fingerprinted copies, the main contents are organized as follows:1. Firstly, the paper provides an overview of the related knowledge about digital fingerprinting, including the background, relative concepts, basic principles and the researches at home and abroad. Then the basic frame, characteristic, classifications, attack techniques and performance measures of fingerprinting system are presented in detail. Based on that, we have analyzed the development directions and the application areas of digital fingerprinting system model, and also explained its requirements as a means of copyright protecting.2. Secondly, the ways and means of research on bandwidth-efficiency of digital fingerprinting system are presented. Commonly, fingerprints can be embedded at the server side, intermediate nodes of a network or the client side. The characteristics of these three embedding scenarioes are studied as well as their advantages and disadvantages. Then, the typical algorithms of each scenario at home and abroad are summarized. As a result, server-side embedding can achive good security but bandwidth-inefficacy, intermediate nodes embedding requires security and cooperation of intermediate nodes which could not be satisfied in reality, and client-side embdedding can utilize the advantages of multicast to eliminate the bottleneck of distribution of fingerprinted copies, but the security should be guaranteed.3. We propose a secure fingerprinting multicast scheme on the client-side based on the stream cipher. It solved the conflicting requirements of single copy transmission for multicast and multiple unique copies for copyright protection,so only one transmission channel was needed. It also lowered the computational load on the server side, shortened the length of unmasking signals greatly, and can resist the estimation attack. The scheme is secure, bandwidth-efficient and robust showed by experiment results and analyse.4. Meanwhile, based on the knowledge of better bandwidth-efficiency of client-side embedding, we propose a new encryption method called shifting-encryption. On this basis, a bandwidth-efficient and anti-collusion fingerprinting scheme is raised. Multi-media is indicated by semantic-feture representation, and desynchronized fingerprint and coded fingerprint are embedded in these two parts independently. Our scheme can get not only good performance of bandwidth-efficiency but also good performance of anti-collusion, for we can detect colluders when little people collude and destroy the vision quality when more people collude.