Improvement of Chien-Jan's authenticated multiple-key agreement protocol without using conventional one-way function

In 2004, Chien and Jan pointed out that Yeh et al.'s authenticated multiple-key key agreement protocol was vulnerable to the impersonation attack. For enhancing the security and key utilization, Chien and Jan proposed an improved protocol. However, Yang and Wang showed that Chien-Jan's protocol is vulnerable to the impersonation attack. This paper proposes an improved protocol to overcome the weakness while maintaining the advantages of Chien-Jan's protocol.