Robust MC-CDMA-Based Fingerprinting Against Time-Varying Collusion Attacks
The design of robust fingerprinting systems for traitor tracing against time-varying collusion attacks in protecting continuous media, such as audio and video, is investigated in this research. We first show that it can be formulated as a multiuser detection problem in a wireless communication system with a time-varying channel response. Being inspired by the multicarrier code-division multiaccess technique, we propose a fingerprinting system that consists of three modules: 1) codeword generation with a multicarrier approach, 2) colluder weight estimation (CWE), and 3) advanced message symbol detection. We construct embedding codes with code spreading followed by multicarrier modulation. For CWE, we show that the weight estimation is analogous to channel response estimation, which can be solved by inserting pilot signals in the embedded fingerprint. As to advanced message symbol detection, we replace the traditional correlation-based detector with the maximal ratio combining detector and the parallel interference cancellation multiuser detector. The superior performance of the proposed fingerprinting system in terms of number of users/identified colluders and the bit-error probability of symbol detection is demonstrated by representative audio and video examples.