Extended asymmetric group key agreement for dynamic groups and its applications

Group Key Agreement (GKA) is a cryptographic primitive allowing two or more entities to negotiate a shared session key over public networks. In existing GKA models, it is an open problem to construct a one-round multi-party GKA protocol. Wu et cd. recently proposed the concept of asymmetric group key agreement (ASGKA) and realized a one-round ASGKA protocol, which affirmatively answers the above open problem in a relaxed way. However, the ASGKA protocol only applies to static groups. To fill this gap, this paper proposes an extended ASGKA protocol based on the Wu et cd. protocol. The extension allows any member to join and leave at any point, provided that the resulting group size is not greater than n. To validate the proposal, extensive experiments are performed and the experimental results show that our protocol is more effective than a plain realization of the Wu et cd. protocol for dynamic groups. The extended protocol is also more efficient than the up-to-date dynamic GKA protocol in terms of communication and computation.