For the Multi-output Support Vector Regression (MSVR) algorithm based on gradient descent method in the process of model parameter fitting, the convergence rate is slow and the prediction accuracy is low. A modified version of the Quasi-Newton algorithm (BFGS) with second-order convergence rate based on the rank-2 correction rule was used to fit the model parameters of MSVR algorithm. At the same time, to ensure the decrease of the iterative process and the global convergence, the step size factor was determined by the non-exact linear search technique. Based on the analysis of the geometry structure of kernel function in Support Vector Machine (SVM), a data-dependent kernel function was substituted for the traditional kernel function, and the multi-output data-dependent kernel support vector regression model was generated. The model was compared with the multi-output support vector regression model based on gradient descent method and modified Newton method. The experimental results show that in the case of 200 samples, the iterative time of the proposed algorithm is 72.98 s, the iterative time of modified Newton's algorithm is 116.34 s and the iterative time of gradient descent method is 2065.22 s. The proposed algorithm can reduce the model iteration time and has faster convergence speed.

Aiming at the problem of designing secure and efficient user authentication protocols with anonymity for wireless sensor networks, based on the widely accepted assumptions about the capabilities of attackers and using the scenarios-based attacking techniques, the security of two recently proposed two-factor anonymous user authentication schemes for wireless sensor networks was analyzed. The following two aspects were pointed out:1) the protocol suggested by Liu etc. (LIU C, GAO F, MA C, et al. User authentication protocol with anonymity in wireless sensor network. Computer Engineering, 2012, 38(22):99-103) cannot resist against offline password guessing attack as the authors claimed and is also subject to a serious design flaw in usability; 2) the protocol presented by Yan etc. (YAN L, ZHANG S, CHANG Y. A user authentication and key agreement scheme for wireless sensor networks. Journal of Chinese Computer Systems, 2013, 34(10):2342-2344) cannot withstand user impersonation attack and offline password guessing attack as well as fall short of user un-traceability. The analysis results demonstrate that, these two anonymous authentication protocols have serious security flaws, which are not suitable for practical applications in wireless sensor networks.

Evolutionary Algorithm based on State-space model (SEA) is a novel real-coded evolutionary algorithm, it has good optimization effects in engineering optimization problems. Global convergence of crossover SEA (SCEA) was studied to promote the theory and application research of SEA. The conclusion that SCEA is not global convergent was drawn. Modified Crossover Evolutionary Algorithm based on State-space Model (SMCEA) was presented by changing the comstruction way of state evolution matrix and introducing elastic search operation. SMCEA is global convergent was proved by homogeneous finite Markov chain. By using two test functions to experimental analysis, the results show that the SMCEA are improved substantially in such aspects as convergence rate, ability of reaching the optimal value and operation time. Then, the effectiveness of SMCEA is proved and that SMCEA is better than Genetic Algorithm (GA) and SCEA was concluded.

Evolutionary Algorithm based on State-space model (SEA) is a new evolutionary algorithm using real strings, and it has broad application prospects in engineering optimization problems. Global convergence of SEA was analyzed by homogeneous finite Markov chain to improve the theoretical system of SEA and promote the application research in engineering optimization problems of SEA. It was proved that SEA is not global convergent. Modified Elastic Evolutionary Algorithm based on State-space model (MESEA) was presented by limiting the value ranges of elements in state evolution matrix of SEA and introducing the elastic search. The analytical results show that search efficiency of SEA can be enhanced by introducing elastic search. The conclusion that MESEA is global convergent is drawn, and it provides theory basis for the application of algorithm in engineering optimization problems.

Since identity authentication becomes an essential mechanism to ensure robust system security in distributed networks, smartcard-based remote user password authentication protocols have been studied intensively recently. Two recently proposed smartcard-based authentication protocols were examined with the scenario-based attack techniques. The protocol presented in “Cryptanalysis and improvement of Liao et al. 's remote user authentication scheme” (PAN Chun-lan, ZHOU An-min, XIAO Feng-xia, et al. Improved remote user authentication scheme. Computer Engineering and Applications, 2010,46(4):110-112) can not withstand the offline password guessing attack as the authors claimed, while the protocol presented in “Improved scheme for smart card password authentication based on bilinear pairings” (DENG Li, WANG Xiao-feng. Improved scheme for smart card password authentication based on bilinear pairings. Computer Engineering, 2010,36(18):150-152) is found vulnerable to the Denial of Service (DoS) attack and insider attack. The analytical results show that, both protocols are susceptible to serious security threats and impractical for security-concerned applications.

Man-in-the-Middle (MitM) attacks pose severe threats to the Robust Security Network (RSN). Based on the state machine model of the authenticator and supplicant in 802.1X-2004, MitM attacks were analyzed systematically from the respect of the whole establishment of RSN associations. With the unilateral cognition of the MitM attacks in RSN clarified, a framework for the MitM attacks in RSN and its conditions of the effective launch of the attacks were brought forward, which were fully verified by an effective attack instance. The analytical results reveal that RSN can withstand MitM attacks if strong mutual authentication methods are adopted; otherwise it is vulnerable to this threat.