Distributed multicast of fingerprinted content based on a rational peer-to-peer community

In conventional multicast transmission, one sender sends the same content to a set of receivers. This precludes fingerprinting the copy obtained by each receiver (in view of redistribution control and other applications). A straightforward alternative is for the sender to separately fingerprint and send in unicast one copy of the content for each receiver. This approach is not scalable and may implode the sender. We present a scalable solution for distributed multicast of fingerprinted content, in which receivers rationally co-operate in fingerprinting and spreading the content. Furthermore, fingerprinting can be anonymous, in order for honest receivers to stay anonymous.