An Enhanced of Simple Three－Party Key Exchange Protocol

Based on the IEEE 802.16e standard, WiMAX proposes a Mobile Multihop Relay (MMR) approach defined in the IEEE 802.16j standard to extend the service area of Base Stations (BSs), and then improves the quality of received signal strength. Clearly, WiMAX MMR achieves a low-cost coverage-extension solution for the existing WiMAX network WiMAX MMR supports three types of Relay Stations (RS): Fixed RS, Nomadic RS and Mobile RS. Each type of RS is with different features on mobility and relay range. Since the relay-based WiMAX network includes different types of RSs, how to efficiently construct the relay-based WiMAX and how to determine an optimal routing path between a Mobile Station (MS) and the MR-BS are two important Issues that should be addressed. This paper thus proposes an IEEE 802.16j-conformed relay-based adaptive cost-based routing approach, in which a multihop optimal path is selected in terms of link bandwidth, path length and channel condition. Numerical results demonstrate that the proposed routing pproach significantly outperforms other approaches in fractional reward loss, network utiliThree-party password authenticated key exchange (3PAKE) protocol is capable of reducing the number of required keys stored by users in a conference. In 2007, Lu and Cao proposed a simple three-party password authenticated key exchange (S-3PAKE) protocol for assisting users to complete business negotiations and agreements during a communication process without requiring a public server key, and the S-3PAKE protocol can resist all known attacks. However, in 2008, Guo et al. pointed out the protocol proposed by Lu et al. still cannot resist man-in-the-middle attacks and online dictionary attacks thus further proposed an improved solution as follows. Two parties execute the 2-PAKE protocol to obtain an agreement key first, so that when they execute the 3PAKE protocol, they can authenticate the real identity with each other. An effective three-party password authenticated key exchange (3PAKE) protocol was proposed for authenticating the real identity of both parties without requiring an execution of the 2-PAKE protocol to obtain the agreement key first, but simply adding the real identity of the opposite party in the communication process, so as to achieve the same security effect.zation and average end-to-end path delay.