Security Analysis of Broadcaster Group Key Exchange Protocols

Group key exchange protocols are basic protocols to provide privacy and integrity in secure group communication. This paper discusses the security of one type of group key exchange protocols and defines the kind of protocols as broadcaster group protocols. It points out two attacks on this kind of protocols. The first attack can be avoided by using fresh values in each action during one session of the group protocol. The second attack should be related with concrete application. It also proposes a dynamic key agreement protocol as an example of solutions at the last part of the paper.

通用可组合符号化分析群组密钥协商协议(英文)

Canetti and Herzog have already proposed universally composable symbolic analysis(UCSA) to analyze mutual authentication and key exchange protocols. However,they do not analyze group key exchange protocol. Therefore,this paper explores an approach to analyze group key exchange protocols,which realize automation and guarantee the soundness of cryptography. Considered that there exist many kinds of group key exchange protocols and the participants’ number of each protocol is arbitrary. So this paper takes the case of Burmester-Desmedt(BD) protocol with three participants against passive adversary(3-BD-Passive) . In a nutshell,our works lay the root for analyzing group key exchange protocols automatically without sacrificing soundness of cryptography.

An Improved ID-Based Group Key Agreement Protocol

ID-based constant-round group key agreement protocols are efficient in both computation and communication, but previous protocols did not provide valid message authentication. An improvement based on attack analysis is proposed in this paper. The improved method takes full advantage of the data transmitted at various stages of the protocol. By guaranteeing the freshness of authentication messages, the authenticity of the generator of authentication messages, and the completeness of the authenticator, the improved protocol can resist various passive and active attacks. The forward secrecy of the improved protocol is proved under a Katz-Yung （KY） model. Compared with existing methods, the improved protocol is more effective and applicable.

A dynamic,secure,and efficient group key agreement protocol

The key challenge of dynamic peer communication is how to realize secure and efficient group key manage-ment.A two rounds key agreement protocol for dynamic peer group(DPG)is proposed in this paper.The protocol,which was obtained by combining the ElGamal encryption scheme with the ElGamal signature scheme,is efficient and simple.The protocol is proven secure against passive attack by using indistinguishable method.Moreover,both perfect forward secrecy(PFS)and key independence(KI)were achieved.Because the protocol is based on the broadcast channel,it is also suitable for key agreement in wireless communications,especially in ad-hoc networks.

Authenticated Group Key Agreement Protocol Based on Twist Conjugacy Problem in Near-Rings

Nowadays some promising authenticated group key agreement protocols are constructed on braid groups, dynamic groups, pairings and bilinear pairings. Hence the non-abelian structure has attracted cryptographers to construct public-key cryptographic protocols. In this article, we propose a new authenticated group key agreement protocol which works in non-abelian near-rings. We have proved that our protocol meets the security attributes under the assumption that the twist conjugacy search problem（TCSP） is hard in near-ring.