The SecureGroup group communication system

The SecureGroup group communication system multicasts messages to a group of processors over a local-area network, and delivers messages reliably and in total order. It also maintains the membership of the group, detecting and removing faulty processors and admitting new and repaired processors. The SecureGroup system provides resistance against Byzantine faults such as might be caused by a captured or subverted processor or by a Trojan horse. The reliable message delivery protocol employs hardware broadcasts and novel acknowledgment mechanisms that reduce the number of acknowledgments and messages required to ensure reliable delivery. The total ordering protocol continues to order messages despite the presence of Byzantine and crash faults, provided that a resilience requirement is satisfied. The group membership protocol operates above the total ordering protocol and, thus, simplifies its design and protects it against malicious attacks.