Research On Dynamic Asymmetric Group Key Agreement Protocols

With the continuous development of computer technology and the Internet, various types of group-oriented applications (such as online conferences, online games, etc.) continue to emerge and have brought great convenience for people's work and lives. However, hackers and criminals are also widely active in every corner of the Internet. Consequently, for these group-oriented applications, the problem of how to provide legitimate group users with secure and reliable group communication has become increasingly important.A group key agreement protocol enables two or more parties to exchange information safely and to agree upon a common session key over an insecure network controlled by some adversaries. The session key generated by an asymmetric group key protocol is asymmetric, which means that the group encryption key is public so any entity in the system can act as the sender, but only the group members can decrypt the cipher-texts and recover the plaintexts. Authenticated group key agreement protocols introduce mechanisms for group membership's acknowledgment which can effectively prevent counterfeiting and repudiation behavior of the group members. Dynamic group key agreement protocols study how to solve the problem of group membership changes more efficiently and safely.Through the analysis and research on some typical asymmetric group key agreement protocols, this paper first proposes a new identity-based aggregate signature scheme and proves its security in the random oracle model, then presents a novel authenticated dynamic group key agreement protocol based on the new scheme. The new protocol only needs one-round of group communication to achieve a variety of membership changes such as member(s) joining, member(s) leaving and both member(s) joining and leaving simultaneously. Moreover, the new protocol meets a variety of security requirements such as known-key security, key-compromise impersonation, unknown key-share security, key control security, perfect forward secrecy, backward secrecy. Last but not least, the efficiency analysis shows that the new proposal has a better performance when compared with the existing asymmetric group key agreement protocols.