Certificateless Authenticated Group Key Agreement Protocol Research

With the rapid development of global information technology, the computer network provides great convenience for people’s communication and information transmission. While, it also puts forward the huge challenge on the information safety protection at the same time. Besides encryption and signature, key agreement is another important cryptographic primitive in cryptography. Group key agreement is widely applied to a lot of cooperation and distributed application scene, such as the multi-party computation, file sharing, distributed audio/video conference and chat system, etc. Therefore, it has important significance in theory and practice to study group key agreement.To realize safe key agreement in the open communication channel, the most important thing is to prevent the adversary from tampering with the message or pretending to be a legitimate user to run the algorithm. Authentication is the best method to solve this problem. Group key agreement protocol with authentication can make users negotiate safely in the open network, and ensure that non-participants of the negotiation can’t obtain the negotiated shared key.With extensive study of the existing group key agreement protocol, we summarize that they are all based on the following two mechanism to authenticate users:the public key infrastructure and identity-based cryptography. But the two methods both have their own defects. In the public key infrastructure, since each user’s public key is corresponding to a certificate, it will bring serious certificate management burden, such as production, save, distribution and update of the certificates. While the identity-based cryptography has the inherent key escrow problem. Because the private key of each user is completely produced by the Private Key Generator, all users must completely trust it.This paper mainly studies the group key agreement protocols which don’t suffer from the above defects. On the base of the analysis of predecessors’research results, we introduce the certificatelcss public-key cryptographic technology into the group key agreement, and put forward the concept of certificateless authenticated group key agreement. In this cryptographic mechanism, the private key of each user is consisted with a partial private key and a secret value chosen by themselves. The partial private key is generated by a partial trusted key generation center. I Ience, this kind of cryptosystem will not suffer from key escrow problem and certificate management problem.Based on the idea of the certificateless public key cryptography, this paper constructs a specific certificateless authenticated group key agreement protocol. It satisfies various typical security properties which are group key agreement protocols need to achieve. More importantly, it dosen’t suffer from the certificate management burden and the key escrow problem. In many resource-constrained open network environment, this is very valuable attribute. In addition, based on the Pairing-Based Cryptography library, we realize the protocol with C language in the Linux environment. The simulation results show that the time cost of the protocol is low, and the protocol is effective and practical.