A communication-efficient and fault-tolerant conference-key agreement protocol with forward secrecy

A conference-key establishment protocol allows participants to construct a common session key that is used to encrypt/decrypt transmitted messages among the participants over an open channel. There are two kinds of conference-key establishment protocols: conference-key distribution and conference-key agreement. In a conference-key distribution protocol, a trusted or elected entity is responsible for generating and distributing the conference key. A conference-key agreement protocol involves all participants cooperatively establishing a conference key. This article designs a secure conference-key agreement protocol with constant round number and message size. Under the decision Diffie-Hellman problem assumption, the resulting protocol is demonstrated to be secure against passive adversaries. Under the random oracle model, the proposed protocol is demonstrated to be provable secure against impersonator attacks and withstand known-key attacks. Compared to previously proposed protocols with round-efficiency, the proposed protocol requires a constant message size for each participant. Furthermore, the proposed protocol possesses both fault tolerance and forward secrecy, while previously proposed protocols with round-efficiency lack one or both properties.