Constructing UC Secure and Constant-Round Group Key Exchange Protocols via Secret Sharing

Ruxandra F. Olimid

Yasser Sobhdel, Rasool Jalili

Chunjie Cao, Chao Jun Yang, Jianfeng Ma +1 more

Group key exchange (GKE) is one of the basic building blocks in securing group communication. A number of solutions to GKE problem have been proposed, but most of them are not scalable and require a number of rounds linear with the number of group members. We present a method of constructing constant-round and identity-based protocol via secret sharing for GKE within universally composability (UC) framework. The resultant protocol focuses on round efficiency and three rounds of communication are required. The protocol allows the batch verification of messages signed by all other group participants. Moreover, compared with other identity-based protocols, the key generation center (KGC) in our protocol is not always online.

Jonathan I. Katz, Moti M. Yung

Chunjie Cao, Jugurta Montalvão

Abstract: Group key management is one of the basic building blocks in securing group communication. A number of solutions to group key exchange have been proposed, but most of them are not scalable and require a number of rounds linear in the number of group members. We formally present a constant-round Identity-based protocol with forward secrecy for group key exchange, which is provably secure in the security model introduced by Bresson et al. Our protocol focuses on round efficiency and the number of communication round is only two. And, the protocol provides a batch verification technique, which simultaneously verifies the validity of messages from other group participants and greatly improves computational efficiency. Moreover, in our protocol, it is no necessary of always-online key generation center during the execution of the protocol compared to other Identity-based protocols. Key-Words:- provable security, identity-based, group key exchange, constant round, secret-share. 1

Jonathan I. Katz, Moti M. Yung