Digital Video Watermarking and the Collusion Attack

This chapter is devoted to the analysis of the collusion attack applied to current digital video watermarking algorithms. In particular, we analyze which are the effects of collusion attacks, with particular attention to the TFA (Temporal Frame Averaging), applied to two basic watermarking systems like Spread Spectrum (SS) and Spread Transform Dither Modulation (STDM). The chapter describes which are the main drawbacks and advantages in using these two watermarking schemes and, above all, which are the fundamental issues to be taken into account to grant a certain level of robustness when a collusion attack is carried out by an attacker.