Secure Acknowledgment of Multicast Messages in Open Peer-to-Peer Networks

We propose a new cryptographic technique, Acknowledgment Compression, permitting senders of multicast data to verify that all interested parties have either received the data or lost network connectivity. Joining the system and acknowledging messages both require bandwidth and computation logarithmic in the size of a multicast group. Thus, the technique is well-suited to large-scale, peer-topeer multicast groups in which neither the source nor any single peer wishes to download a complete list of participants. In the event that a high percentage of nodes are malicious, a message may fail to verify. However, in such cases the source learns the real network address of a number of malicious nodes.