An Efficient Authentication Infrastructure of WLAN Based on Self-Updating Hash Chain

Two standards for security of WLAN,IEEE 802.11 i and WAPI,are introduced,and some shortcomings of them are pointed out.Based on hash chains technique to construct identity authentication tokens, a new authentication infrastructure for WLAN is proposed,in which AS authenticates the main entities -STAs in the foremost time.Properties of the proposed scheme are discussed,including security, efficiency and feasibility etc.Compared with 802. 11 i and WAPI,the proposed scheme not only improves efficiency by reducing cost on computation and communication,but also promotes security property -availability by mitigating DoS attacks to AP and AS.At the same time,a self-updating hash chain technique is presented that is embedded in the proposed infrastructure to solve the length limitation of traditional hash chain.

Interruption Tolerance Routing Strategy for Space Information Network

Frequent inter-satellite link(ISL)handovers will induce service interruption in large-scale space information networks,since traditional distributed/centralized routing strategy-based route convergence/update will consume considerable time(compared with ground networks)derived from long ISL delay and flooding between hundreds or even thousands of satellites.During the network convergence/update stage,the lack of up-to-date forwarding information may cause severe packet loss.Considering the fact that ISL handovers for close-to-earth constellation are predictable and all the ISL handover information could be stored in each satellite during the network initialization,we propose a self-update routing scheme based on open shortest path first(OSPF-SUR)to address the slow route convergence problem caused by frequent ISL handovers.First,for predictable ISL handovers,forwarding tables are updated according to locally stored ISL handover information without link state advertisement(LSA)flooding.Second,for unexpected ISL failures,flooding could be triggered to complete route convergence.In this manner,network convergence time is radically descended by avoiding unnecessary LSA flooding for predictable ISL handovers.Simulation results show that the average packet loss rate caused by ISL handovers is reduced by 90.5%and 61.3%compared with standard OSPF(with three Hello packets confirmation)and OSPF based on interface state(without three Hello packets confirmation),respectively,during a period of topology handover.And the average endto-end delay is also decreased by 47.6%,9.6%,respectively.The packet loss rate of the proposed OSPF-SUR does not change along with the increase of the frequency of topology handovers.