Insider Attack on A Password-Based Group Key Agreement
Hongtu Li, Liang Qing Hu, Wei Yuan, Hongwei Li, Jianfeng Chu · Procedia Engineering · 2011
In 2009, Zheng et al. proposed an efficient password-based group key agreement protocol resistant to the dictionary attacks by adding password-authentication services to a non-authenticated multi-party key agreement protocol proposed by Horng. They claimed that the proposed protocol is very efficient since it only requires constant rounds to agree upon a session key, and each user broadcasts a constant number of messages and only requires four exponentiations. Under the Decisional Diffie-Hellman assumption, they shown the proposed protocol is provably secure in both the ideal-cipher model and the random-oracle model. But in this paper, we show that the protocol Zheng et al. proposed is vulnerable to an active insider attack.