New intra-video collusion attack using mosaicing

Recent efforts for watermarking digital video extend the results obtained for still image watermarking. As a result, most of the proposed algorithms rely on a frame-by-frame approach. Such an adaptation leads to unreliable algorithms in terms of security. The goal of this article is to stress the problem of collusion when digital watermarked data is distributed at large scale and especially intra-video collusion in the context of video. Three simple collusion attacks are described before being evaluated on two alternative video watermarking algorithms based on the spread spectrum technique. Finally, some experimental results are presented confirming the danger of intra-video collusion and some perspectives are discussed.