Multi-receiver/multi-sender network security: efficient authenticated multicast/feedback

The authors extend the use of traditional point-to-point message authentication to multireceiver and/or multisender scenarios. They provide efficient cryptographic authentication methods for point-to-multipoint communication, where a single sender can broadcast (multicast) only one unconditionally secure authenticator for a message and which all receivers can verify. They further develop multipoint-to-point communication (incast) in which any subset (of a specified size) of a group of individuals can transmit a single authenticator (or a signature) for a message using the group´s key. This method has been called threshold authentication. It is an application layer that is transparent to the receiver which only deals with the group as one entity. The bandwidth, computations, and storage overheads are reduced substantially when compared with the traditional approach. Threshold authentication hides some aspects of the internal structure of the group, which may be important in interenterprise communication