Watercasting paper at Workshop on Networked Group Communication

Our paper on Watercasting: Distributed Watermarking of Multicast Media has been accepted for publication in the 1st International Workshop on Networked Group Communication, to be held in Pisa, Italy, in November 1999.

The paper describes a scheme by which encrypted multicast audiovisual data may be watermarked by lightweight active network components in the multicast tree. Every recipient receives a slightly different version of the marked data, allowing those who illegally re-sell that data to be traced. Groups of cheating users or multicast routers can also be traced. The source sends multiple subtly different copies of each video packet, ensuring that the number of copies exceeds the depth of the multicast distribution tree. At each hop, on a per-outgoing link basis, the router discards one copy according to a pseudo-random function with known key. When the data reaches the receivers at a leaves of the tree, only copy of each packet remains for each receiver. Due to the pseudo-random discard, the pattern of received packets for the video sequence will be different at each receiver, providing a unique watermark. Full details are provided in the paper.