DDoS detection has been the research focus in the field of information security. Existing detecting methods such as Hurst parameter method and Markov model must ensure that the network traffic signal f(t) is a stationary signal. But its stability is just a regular assumption and has no strict mathematical proof. Therefore methods mentioned above lack of reliable theoretical support. This article introduces Hilbert-HuangTtransformation(HHT) . HHT does not need to be based on signal stability,but it monitors the similarity between Hilbert marginal spectrums of adjacent observation sequences so as to realize DDoS detection. The method is experimented on DARPA 1999 data and simulating data respectively. Experimental results show that the method behaves better than existing Hurst parameter method in distinguishing both the normal and the attacked traffic.
A new Network Coding mechanism in WSNs(Wireless Sensor Networks), which is named COEQ and aims at balancing coding opportunities, energy and QoS, is proposed and analyzed. Implemented on the basis of traditional AODV protocol, COEQ evaluates several metrics of paths comprehensively with TOPSIS method including minimum remaining energy, coding opportunities, QoS and so on, so as to select the optimal transmitting route. Experiments on NS[2] show that COEQ can improve throughput and save energy when the transmitting rate is low.
Identity-based cryptography （IBC） has drawn a lot of attentions in delay tolerant environment. However, the high computational cost of IBC becomes the most critical issue in delay tolerant mobile sensor network （DTMSN） because of the limited processing power. In this paper, an efficient identify-based signature scheme with batch authentication （ISBA） is proposed for DTMSN. ISBA designs an online/offline signature with batch authentication to reduce the computational cost, and improves data delivery mechanism to increase the number of messages for each batch authentication. Simulation results show that ISBA not only realizes a lower computational cost than existed schemes, but also does not induce negative impact on the delivery performance.
LI Wen-jiZHENG Kang-fengZHANG Dong-meiYE-QingYANG Yi-xian
