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25 March 2015, Volume 36 Issue 3

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academic paper

Personalized trajectory privacy preserving method based on graph partition

Jing YANG,Bing ZHANG,Jian-pei ZHANG,Jing XIE

2015, 36(3):  1-11.  doi:10.11959/j.issn.1000-436x.2015053

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A (s,λ)-overlap was proposed which based on the angle and location between two trajectories to construct the relationship between them, and also measure the weight between two trajectories by trajectory angle and distance, to-gether to construct the personal trajectory graph model. Then a greedy partition method to was proposed construct trajec-tory k-anonymization sets by finding the approximate optimal k trajectories. Experiment results on synthetic dataset show the effectiveness and reasonableness of proposed method.

Towards cooperation location privacy-preserving group nearest neighbor queries in LBS

Sheng GAO,Jian-feng MA,Qing-song YAO,Cong SUN

2015, 36(3):  12-20.  doi:10.11959/j.issn.1000-436x.2015054

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On the basis of analyzing the existing location privacy protections in GNN queries, a GNN queries method for location privacy protection in LBS was proposed. In this method, a distributed system structure for GNN was adopted to overcome the disadvantages of centralized anonymous system structure such as making a communication bottleneck and being a vulnerable point of attack. According to the motion status of a user group, two methods on the basis of this struc-ture, named location random perturbation and threshold secret sharing version of Paillier cryptosystem, were used to se-curely compute the center location of the user group. Then these users' GNN queries had been turned into NN queries of the group center. Compared with existing related work, theoretical analysis proves that the proposal can effectively resist against the existing distance interaction attack and collusion attack and achieve flexible GNN queries, while it costs lower network resources.

Message forwarding based on periodically evolving social characteristics in opportunistic mobile networks

Yong-feng HUANG,Yong-qiang DONG,San-feng ZHANG,Guo-xin WU

2015, 36(3):  21-32.  doi:10.11959/j.issn.1000-436x.2015055

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To avoid monster community problem which suffered by distributed k-clique community detection, τ-window community detection was proposed. In addition, τ-window centrality estimation was put forward. By investigating the periodic evolution of τ-window community and τ-window centrality, two new metrics, TTL(time to live) community and TTL centrality, were proposed to improve the prediction of the node's encounter during the message's lifetime. Moreover, a social-aware routing algorithm, PerEvo, was then designed based on them. Extensive trace-driven simulation results show that PerEvo achieves higher message delivery ratio than the existing social-based forwarding schemes, while keep-ing similar routing overhead.

Secure localization scheme against wormhole attack for wireless sensor networks

Hong-long CHEN,Zhi-bo WANG,Zhi WANG,Jiang-ming XU,Yan-jun LI,Li-ping LIU

2015, 36(3):  33-40.  doi:10.11959/j.issn.1000-436x.2015056

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As one of the key technologies in wireless sensor networks (WSN), localization is the basis of many WSN-based applications. However, WSNs are often deployed in the hostile environment, in which the attackers can eas-ily disrupt the localization procedure of the nodes. The effects of wormhole attack on the DV-Hop localization procedure are analyzed firstly, after which a secure localization scheme against the wormhole attack is proposed. The simulation re-sults illustrate that the proposed secure localization scheme can efficiently reduce the effects of the wormhole attack on the DV-Hop localization, which validates the effectiveness of the proposed scheme.

Cooperative transmission scheme of relay selection combined with network coding and its performance analysis

Bao-feng JI,Kang SONG,Yi WANG,Yong-ming HUANG,Lv-xi YANG

2015, 36(3):  41-51.  doi:10.11959/j.issn.1000-436x.2015057

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The outage probability and average BER (bit error ratio) of two-way relay system with network coding using relay selection were analyzed over Nakagami channels. The cooperative relay selection criterion of minimizing the worse user's BER was proposed based on three time slots network coding. The closed-form expressions of outage probability and average BER were derived through theoretical analysis from the point of two-way communication; meanwhile, the analytical expressions of outage probability and average BER of two-way relay system using network coding without cooperative relay selection were also obtained rigorously. By the analysis of two-way relay system without cooperative relay selection, it was found that the performance gains of the proposed scheme would increase gradually with the Naka-gami channel fading parameters decreasing. Simulation results verified the correctness of theoretical analysis and illus-trated that the performance of the proposed scheme can be improved significantly relative to the network coding without cooperative relay selection.

Energy efficient cooperative spectrum sensing algorithm in cognitive wireless sensor networks

Gui-cai YU,Cheng-zhi LONG,Man-tian XIANG

2015, 36(3):  52-62.  doi:10.11959/j.issn.1000-436x.2015058

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A novel energy-efficient scheme of cooperative spectrum sensing in cognitive wireless sensor networks is proposed.Firstly,in order to reduce energy consumption of distributed sensor nodes,and assumed that instantaneous SNR and average SNR for each node is available.The mathematical model of spectrum sensing nodes energy consumption and optimum detection threshold are analyzed. Then, the theory of sensing node selection and decision threshold setting, combined an effective cooperative spectrum sensing scheme based on decision nodes selection is researched. The analy-sis and simulation results show that the proposed algorithm can effectively reduce total energy consumption in cognitive sensor networks, improve energy efficiency.

Coding redundancy controlled data forwarding mechanism in opportunistic networks

Da-peng WU,Peng-wen LOU,Qiao-shou LIU,Yu XIONG,Ru-yan WANG

2015, 36(3):  63-74.  doi:10.11959/j.issn.1000-436x.2015059

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The network coding can improve network transmission efficiency. But most of the data forwarding mechanism does not consider the iteration redundancy control during data transmission. In order to reduce the complexity of decod-ing and iteration redundancy copies sufficiently in coding nodes limited network, the encounter duration estimating method and coding opportunity-aware method are proposed. Further, a data forwarding mechanism for coding redun-dancy control with communication capacity estimating method is designed. It can make full use of the encounter duration between nodes to forward the data, which has more coding opportunity and less than the community capacity. Further-more, the coding number of nodes is updated and the iteration redundancy in every generation is controlled. Experimental results show that, the mechanism could reduce the iteration redundancy in the network and minimize data amount re-quired by decoding, which tends to the theoretical minimum and improves the utilization of network resources.

Security analysis and improvement of a certificateless signcryption scheme

Zhen-guo ZHAO

2015, 36(3):  75-80.  doi:10.11959/j.issn.1000-436x.2015060

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To solve the certificate management problem in the traditional public key cryptography and the key escrow problem in the identity-based public key cryptography, Al-Riyami and Paterson proposed the concept of the certificateless public key cryptography.Recently,Zhu et al.proposed a certificateless signcryption without bilinear pairings.However， their scheme was completely insecure against with two concrete attacks. A strongly secure certificateless signcryption without bilinear pairings was also proposed, which was provably secure in the random oracle model under the assumption that the discrete logarithm problem and the computational Diffie-Hellman problems were intractable. Furthermore, the efficiency of the proposed scheme is very high since only four modular exponentiations and five modular exponentiations are needed in the signcryption algoriahm and unsigncryption algorithm separately.

Academic communication

Design and implementation of a network measurement and analysis system in OpenFlow networks

Xi WENG,Ming CHEN,Guo-min ZHANG,Bo XU,Chang-you XING

2015, 36(3):  81-88.  doi:10.11959/j.issn.1000-436x.2015061

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Nowadays OpenFlow networks lack an effective measurement means supporting for quantificationally analyz-ing and measuring various innovative applications or mechanisms yet. On the basis of upgrading equipments in Open-Flow networks to be measurement entities which function local log, a mechanism that the measurement entities can carry out the distributed measurement controlled by a centralized server OpenTrace server is designed, and a communications specification called OpenFlow measurement control protocol (OMCP) is established. Meanwhile, a function to analyze the measurement logs, which is based on the regular expression, hash technique and extended statistical function base, is designed. The experimental results of the prototype show that OpenTrace can flexibly deploy and control the distributed measurements; not only the transmission process of dataflow in the data plane but also the interactive process of control-ling events in the control plane can recur quantificationally by OpenTrace system, and the comprehensive performance data can be provided for the quantificational analysis of applications and new mechanisms in OpenFlow networks.

Improved meet-in-the-middle attack on ARIA cipher

Man-man LI,Shao-zhen CHEN

2015, 36(3):  89-94.  doi:10.11959/j.issn.1000-436x.2015062

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A study on the structure of ARIA cipher is presented. A new 4-round distinguishing property for the meet-in-the-middle attack on ARIA cipher is presented by making use of the multiset and the truncated differential char-acteristic. The new distinguishing property improves the meet-in-the-middle attack on 7 rounds of ARIA-192 cipher ef-fectively by reducing the 30 parameters to 16. The new attack requires a precomputation complexity of 2^135.3and a time complexity of about 2¹²³.

Link-first based quick coordinated virtual network embedding algorithm

Wen-cheng XIONG,Ying WANG,Xue-song QIU,Wen-jing LI

2015, 36(3):  95-103.  doi:10.11959/j.issn.1000-436x.2015063

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In order to reduce costs of link embedding and increase revenue, a coordinated embedding algorithm based on link-first is proposed. The algorithm embeds link and node alternately, and embeds the virtual link that with greater band-width requirement first to the physical path that with fewer link hops by using the greedy method, and ultimately aims at re-ducing average costs of virtual network embedding and improving acceptance rate of virtual network. Simulation results show that, compared with the existing algorithms, this embedding algorithm saves link cost significantly, improves accep-tance rate of virtual network and revenue of the physical network, and can effectively shorten the running time.

Cracking-resistance net-flow fingerprint scheme based on multi-dimensional orthogonal carriers

Cheng LEI,Hong-qi ZHANG,Yi SUN,Xue-hui DU

2015, 36(3):  104-114.  doi:10.11959/j.issn.1000-436x.2015064

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Aimed at problems of unknown source identity, uncontrollable net-flow exchange and untraceable flow- ex-changing paths, it proposes cracking-resistance net-flow fingerprint scheme based on multi-dimensional orthogonal carri-ers. It uses two mutually orthogonal carriers so as to improve the capacity of fingerprint information. It achieves crack-ing-resistance by interval centroid carrier characteristics and hidden Markov model based decoding technique. Ultimately, it improves the robustness of scheme. What's more, it analyzes the resistance of multi-flow attack ability by using cen-troid attribute value to select embedding carriers randomly. Besides, it analyzes accuracy of fingerprint centroid algorithm and quantization index modulation decoding technique based on HMM under different cases. Finally, its invisibility and robustness is evaluated by experiments.

Academic paper

Joint transceiver beamforming in MIMO cognitive radio network

Yan GUO,Fang-jun ZHU,Ning LI,Xiao-yun YUAN

2015, 36(3):  115-123.  doi:10.11959/j.issn.1000-436x.2015065

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An iterative SDP-MMSE algorithm based on semidefinite programs (SDP) and minimum mean squared error (MMSE) was introduced to minimize the total transmit power. And a further approach on the max-min fairness beam-forming was presented. Simulation results demonstrate that proposed algorithms have superior performance in terms of total transmitted power and signal-to-interference plus noise ratio (SINR) as compared to the existing ones.

Side channel attack of cipher chips based on difference variability

Yang ZHANG,Kai-yan CHEN,Xiong-wei LI,Jun-guang CHEN,Yan LI

2015, 36(3):  124-129.  doi:10.11959/j.issn.1000-436x.2015066

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Side channel attack (SCA) has the problems of high sample quantity and long analysis time. Noise of side channel leakage and its differential reduction method are researched combined with the architecture of micro control unit (MCU). Signal difference variability and hamming weight difference variability are defined, whose inverse proportion is checked. Method of key analysis based on difference variability is proposed, which uses its change property in encrypt process. Data encryption standard (DES) is cracked in experiment, which only needs 150 power tracks and 1.03 s analysis time. The attack method can be extended to crack other block ciphers which implemented in general purpose MCU.

Coherent parameters estimation and coherent performance analysis for distributed aperture coherent radar

Jing SONG,Jian-yun ZHANG,Wen-gang ZHANG

2015, 36(3):  130-138.  doi:10.11959/j.issn.1000-436x.2015067

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The closed-form CRB (cramer-rao bounds) of the coherent parameters estimation, which include time delay differences and total phase differences, are derived for the distributed aperture coherent radar with general architecture firstly. Then under the assumption that time delay and phase synchronization errors are all existing, the performance bound of oSNRg (output signal-to-noise ratio gain) is developed based on the aforementioned CRB (Cramer-rao bounds). It is concluded that: the CRB of total phase differences is independent on the carrier frequency and effective bandwidth. More transmitters give higher oSNRg. However, as the number of receivers increase, the oSNRg gradually improve with the input SNR being high sufficiently, and worsen with the input SNR being low. Finally, the numerical examples dem-onstrate the validity of the theoretical results.

Recognition of PQ stego images based on identifiable statistical feature

Ji-cang LU,Fen-lin LIU,Xiang-yang LUO,Yi ZHANG

2015, 36(3):  139-148.  doi:10.11959/j.issn.1000-436x.2015068

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A PQ (perturbed quantization) stego images recognition algorithm is proposed based on identifiable statistical feature. According to the specific changing ways of PQ steganography to image data, the proposed algorithm extracts the identifiable statistical feature that can distinguish PQ stego images from other types of stego images. Then, the SVM (support vector machines) classifier is trained to recognize PQ stego images. Experimental results show that, the proposed algorithm can reliably recognize PQ stego images from multi-class stego images generated by five types of well-known JPEG steganography (PQ、F5ns、F5、MB1 and MOD). Even though the stego images generated by F5、nsF5、MB1 and MOD are not used for training classifier, the proposed algorithm can still effectively recognize PQ stego images.

Reasearch on network delay of Internet

Chuan LIN,Hai ZHAO,Yuan-guo BI,Si-yuan JIA

2015, 36(3):  149-160.  doi:10.11959/j.issn.1000-436x.2015069

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Research on the delay of the Internet under marcrotopology plays an important role in comprehension of Inter-net architecture structure and performance. Using effective samples in four different regions authorized by CAIDA Ark and getting network delay, there is little relationship between network delay and communication diameter and the number of the effective paths happening dominant delay is over 70%. The analysis presents that it is dominant delay that affects the relationship between the network delay and the communication diameter. The geographic mapping of the link hap-pening dominant delay supposes that the dominant delay happens frequently in the link across one city in a country. Fi-nally, the conclusion is draw that queue delay is the major composition of the dominant delay for a short range(less than 5 000 km),whereas the propagation delay is the main factor for a long distance(greater than 5 000 km).

Flow-awared identification model of sophisticated network application

Luo-shi ZHANG,Da-wei WANG,Yi-bo XUE

2015, 36(3):  161-169.  doi:10.11959/j.issn.1000-436x.2015070

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Traditional methods of protocol identification, which is mainly based on individual flow, lose their effective-ness as dealing with sophisticated network applications. A novel model of identifying sophisticated network applications, called flow-aware model, is addressed. This proposed model abstracts the characteristics of sophisticated network appli-cations from spatial dimension, time dimension and flow dimension, and provides the detailed analysis and deeply mining in characteristics of behaviors and states. Based on this model, a framework and method of sophisticated network appli-cations identification is proposed. The experimental results demonstrate that the proposed method can achieve the pur-pose of identifying sophisticated network applications effectively.

Blind Turbo equalization algorithm based on hidden Markov model for continuous phase modulation signals

Kai ZHONG,Hua PENG,Lin-dong GE

2015, 36(3):  170-178.  doi:10.11959/j.issn.1000-436x.2015071

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To solve the issues of the poor performance and convergence difficulties in the blind equalization of high order continuous phase modulation (CPM) signals, a new EM-SOVA channel blind equalization method was developed from the perspective of hidden Markov model(HMM). A novel blind Turbo equalization algorithm for high order CPM signals was proposed based on the combination of this method and Turbo equalization. The algorithm improved the equalization performance by applying the soft-output Viterbi algorithm(SOVA) within an EM iteration. Simultaneously, a soft infor-mation iterative process was used for further improvement of the system performance at a low signal-to-noise ratio. The analysis and simulation results show that the proposed algorithm provides a good blind equalization performance and convergence.

Analysis of influence of ionosphere and troposphere model on RAIM availability of COMPASS

Wei-dong JIAO,Zhi-hu TANG,Xiao-yun SHEN

2015, 36(3):  179-186.  doi:10.11959/j.issn.1000-436x.2015072

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The ionosphere and troposphere are main error sources of satellite navigation system measurement and main factors of COMPASS availability. The influence of the ionosphere and troposphere delay error model on the RAIM availability of COMPASS is analyzed in simulation where ephemeris datum is adopted, and especially the influence of different troposphere models on RAIM availability in civil aviation is analyzed. The experiment at results shows that the delay error of ionosphere and troposphere changes from 0 to 14.555 9 m and 0 to 23.779 6 m correspondingly. And for the non-precision approach stage of civil aviation, when Saastamoinen model, UNB3 model and Hopfield model are used as the troposphere model of COMPASS respectively, the RAIM availability is 99.308%, 92.041 5% and 100% corre-spondingly. So it is more suitable that Hopfield model is used as the troposphere model of COMPASS and the 99.9% RAIM availability requirement in civil aviation can be achieved using this model.

Cooperative caching scheme based on the minimization of total cost for P2P caches

Yin-long LIU,Min WANG,Wei MA,Xu ZHOU,Ya-hui HU

2015, 36(3):  187-194.  doi:10.11959/j.issn.1000-436x.2015073

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To reduce the total cost of P2P cache system, a cooperative cache scheme based on the minimization of total cost is proposed. In the scheme, delivery cost and storage cost are taken into account, and inter-ISP cost, popularity, file size, storage cost are used to evaluate each object's caching gain value, which is a new concept defined to estimate the benefits of storing or replacing an object. When a replacement is needed, the objects with the minimum caching gain value will be evicted. Simulation results show that the proposed scheme can effectively reduce the total cost of P2P cache system.

Source-controlled OpenFlow data plane

Zhe WANG,Man-gui LIANG,Xiao-meng JI,MateusAbisai Fillipus

2015, 36(3):  195-201.  doi:10.11959/j.issn.1000-436x.2015074

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An OpenFlow switch typically used TCAM to speed up flow table matching. Therefore it brought problems with scale, high cost and energy consumption. To resolve these issues, a novel model called the source-controlled Open-Flow(SCOF)was proposed. SCOF used a source routing address named vector address (VA) as the switching label of the packet. VA defined the communication path. The core of SCOF data plane is vector switch. It can accomplish the data forwarding process relying only on VA, instead of flow table matching. SCOF overcomes scale problem by reducing the complexity of switch hardware and simplifying the process of updating flow table.

Algorithm for blind separation of PCMA based on CHASE decoding

Jian DU,Ke-xian GONG,Hua PENG

2015, 36(3):  202-207.  doi:10.11959/j.issn.1000-436x.2015075

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On the basis of SOVA-PSP, a novel algorithm for blind separation of PCMA signal was presented based on CHASE decoding. The results of soft output of SOVA-PSP were sorted based on reliability in the algorithm, the mixed symbols that had low reliability in the sorted results were reconstructed. Compared the euclidian distance between recon-structed signal and received signal, the wrong results can be corrected. Simulation results show that compared with the SOVA-PSP algorithm, the novel algorithm can improve the gain of about 2 dB.

Study of the ternary correlation quantum-behaved PSO algorithm

Tao WU,Xi CHEN,Yu-song YAN

2015, 36(3):  208-215.  doi:10.11959/j.issn.1000-436x.2015076

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In order to more effectively utilize existing information and improve QPSO's (quantum-behaved particle swarm optimization) convergence performance, the ternary correlation QPSO (TC-QPSO) algorithm was proposed based on the analysis of the random factors in location formula. The novel algorithm changed the information independent ran-dom processing method of standard QPSO and established internal relations during particles' own experience information, group sharing information and the distance from the particles' current location to the population mean best position using normal copula functions.Then, the method of generating ternary correlation factors was given by using the Cholesky square root formula. The simulation results of the test functions showed that TC-QPSO algorithm outperforms the stan-dard QPSO algorithm in terms of optimization results, given that the negative linear correlation exists betweenu and r1 or u andr2.

Modeling and analysis of Cloud-P2P storage architecture

Shun-fu JIN,Chen-fei WANG,Ling-ling CHEN,Zhan-qiang HUO

2015, 36(3):  216-223.  doi:10.11959/j.issn.1000-436x.2015077

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Based on the Cloud-P2P storage architecture, taking into account the data access mechanism with both the data center and the peer-based layer, considering the repair process of the replica, a three-dimensional Markov chain model was constructed. The steady-state analysis of the model is obtained by using a matrix-geometric method. Then, the per-formance measures in terms of peer-based traffic load, the average access time, and the repair rate are given. Moreover, numerical results with analysis and simulation are provided to demonstrate the influence of the system parameters on the system performance. By constructing a benefit function, the number of replicas in peer-based layer is optimized.

Resource assignments algorithm based on energy efficiency optimization in OFDM relay networks

Yun LI,Hai-xia DUAN,Kai-rong SU,Bin CAO

2015, 36(3):  224-231.  doi:10.11959/j.issn.1000-436x.2015078

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In cooperative orthogonal frequency division multiplexing (OFDM) systems, the resource allocation rationally is significant to enhance the system performance. Aiming at maximizing the total system energy efficiency, the joint as-signment problem of relay, sub-carrier and power among users is modeled. Since the joint assignment issue subject to each user's maximal energy efficiency under minimal capacity constraints can be modeled as a NP-hard problem, a suboptimal algorithm is proposed to solve this problem. The proposed algorithm uses the conflict graph (CG) to denote the possible resource conflict relations. Then, the resource is assigned using maximal weight independent set (MWIS) algorithm. Numerical results demonstrate that the proposed algorithm (JRAA) can improve the system energy efficiency by joint assignment of relay,sub-carrier and power.

Nonlinear companding transform for PAPR reduction in lattice-OFDM system

Si-ming PENG,Yue-hong SHEN,Zhi-gang YUAN,Yu-wei MIAO,Wei JIAN

2015, 36(3):  232-239.  doi:10.11959/j.issn.1000-436x.2015079

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Since the inherent higher peak-to-average power ratio (PAPR) in lattice OFDM (LOFDM) is higher than that of conventional OFDM systems, a novel continuous and differentiable nonlinear companding scheme is investigated and analyzed when employing the conventional companding transforms. By making full use of the characteristic of the Gaus-sian-distributed original signals and employing a truncation to the distribution function of the original signals, the com-panded signals can be restricted in a specific region which consistents with the distribution of original signals. Therefore, the companded signals can not only achieve an improved PAPR and bit error ratio (BER) performance but also maintain the statistical characteristics of the original signals. Theoretical analysis and simulation results demonstrate that the pro-posed scheme substantially outperforms the conventional nonlinear companding schemes.

Low complexity acquisition algorithm for GPS signals with low SNR and high dynamic

Zhu-lin XIONG,Ce-lun LIU,Jian-ping AN,Ze-bin XIE

2015, 36(3):  240-245.  doi:10.11959/j.issn.1000-436x.2015080

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A frequency-domain segmental shift average periodogram acquisition algorithm for GPS signals with low SNR and high dynamic was proposed. First, the parallel rough compensation of Doppler frequency rate and C/A code phase as well as segmental FFT was applied with the received signal. Second, the compensation interval was extended to precise estimation interval based on the number of data segments. Third, the branch with the nearest compensation value was chosen as the estimation branch of each estimation value and the difference of two values was reduced by segmental fre-quency spectrum shift. The correlation value of each estimation branch was obtained by non-coherent accumulation of all shifted frequency spectrums. Last, the maximum correlation value was sent to a constant false alarm rate detector to de-termine whether the acquisition was success. The results show that compared with the traditional periodogram algorithm, the proposed algorithm has much lower computational complexity and a little performance loss.

Avaliability model for reconfigurable network

Liang ZHAO,Xiao-hui ZHANG,Yu WANG

2015, 36(3):  246-253.  doi:10.11959/j.issn.1000-436x.2015081

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For network fault recovery mechanisms can have a significant impact on network performance reconfigurable actual situation theoretically analyze the running reconfigurable networks, a reconfigurable network availability model is proposed. In this model, quantitative description of the node service capabilities and network services capabilities, based on reconfigurable network by introducing state transition theory, finite-state Markov chain theoretical analysis. To verify the validity of the availability of the model by simulation, simulation results show that the theoretical model calculations and simulation results fit better, can be used to describe the specific performance reconfigurable networks available.

Towards load adaptive routing based on link critical degree for delay-sensitive traffic in IP networks

Yang YANG,Jia-hai YANG,Hui WANG,Chen-xi LI,Yu-ding WANG

2015, 36(3):  254-264.  doi:10.11959/j.issn.1000-436x.2015082

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Delay-sensitive traffic requires lower end-to-end delay in IP networks, such as online video, VoIP, video con-ference. Based on the criticality degree of link. A load adaptive routing algorithm (LARA) was presented which could avoid the link to be congested to reduce the end-to-end delay. Firstly, an optimization objective function has been put forward; and then decomposed into several sub-functions by using convex optimization theory; finally, the optimization objective function and sub-functions were transformed into a simple distributed protocol. LARA with ECMP (equal-cost multipath) routing strategy was compared which was widely deployed in the network by using NS2 simulation under CERNET2 topology. By evaluating the feedback delay, packet loss rate and traffic load, the results show that LARA can exhibit good performance and achieve excellent load balance, and meanwhile improve the robustness of the link when using multipath routing technology.

Key distribution and recovery algorithm based on Shamir's secret sharing

Hui-gui RONG,Jin-xia MO,Bing-guo CHANG,Guang SUN,Fei LONG

2015, 36(3):  265-274.  doi:10.11959/j.issn.1000-436x.2015083

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In Shamir's secret sharing scheme, the dealer divided the secret s into n shadows and distributed it to share-holders in such a way that any t or more than t shadows can recover this secret, while fewer than t shadows cannot obtain any information about the secret s. During the actual secret recovery process, there exist other cases with more than t par-ticipants. The case of secret sharing problem was discussed based on Shamir's secret sharing scheme and reconstructs the secret by introducing a linear combination of shadows—Lagrange factor. Then, the improved algorithm of key distribu-tion and recovery was proposed and extended to a multi-secret sharing scheme. Theoretical analysis and simulation show that the improved scheme improves its security under the same conditions of complexity.

Academic communication

Research on the method of virtual machine deployment in cloud computing

Xiao-yan ZHANG,Min-ne WANG,Xiao-feng DU

2015, 36(3):  275-285.  doi:10.11959/j.issn.1000-436x.2015084

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A method of virtual machine deployment was proposed. The main purpose of the method was to reduce the resource fragments on the host. The method predicted the increment of the virtual machines of different specifications in the next period of time, and dynamically programmed the available CPU and memory of the host in the resources pool by the prediction. The method took into account the users' behaviors, pre-determined the resources allocation rules, when users applied a virtual machine, the virtual machine would be assigned to the specific host directly. In the end, the method was implemented on the CloudStack platform.The experiment demonstrates that the method can reduce the resource fragments effectively.