Table of Content

    25 September 2015, Volume 2015 Issue 5 Previous Issue    Next Issue
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    Privacypreserving range query processing in wireless sensor networks
    2015, 2015 (5):  1-13.  doi: 10.3969/j.issn.1000-5641.2015.05.001
    Abstract ( 882 )   PDF (1875KB) ( 1650 )   Save
     This paper provides a stateoftheart survey of privacypreserving range query processing techniques in Wireless Sensor Networks (WSNs). We first introduce the research models, including network models, adversary models and performance evaluation models. Then, we classify existing related work into several types according to privacy preservation techniques, such as Bucketing Scheme, Prefix Membership Verification, and Orderpreserving Encryption. We further elaborate the key mechanisms of typical protocols. Performance analysis and comparison show that existing work cannot balance privacy, integrity, efficiency and accuracy. Finally, we provide some suggestions for future research.
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    Review on location privacy protection research
    QIN Bo,TANG Qiu-nan,WANG Mei-qi
    2015, 2015 (5):  14-27.  doi: 10.3969/j.issn.1000-5641.2015.05.002
    Abstract ( 1511 )   PDF (2400KB) ( 1043 )   Save
    In recent years, with the development of wireless communication technology and mobile positioning technology, applications relating to locationbased services (LBS) are increasingly taken seriously and used widely. On the one hand, LBS brings people considerable convenience; on the other hand, it becomes a nonnegligible security threat that users’ privacy, mainly including location privacy, trajectory privacy and identity privacy, could be leaked out. Many solutions on the basis of different structures of privacy protection system have been proposed by researchers at home and abroad, which can be divided into pseudonym, faked locations and spatial and temporal cloaking, protecting users’ identity privacy, location privacy and trajectory privacy respectively. In this paper, we contrast the existing privacy protection technologies and analyze challenges LBS is facing. At the same time, we conclude the existing researches and give directions for future research.
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    Privacy protection in locationbased services: Model and development
    ZHAO Da-peng,LIANG Lei,TIAN Xiu-xia,WANG Xiao-ling
    2015, 2015 (5):  28-45.  doi: 10.3969/j.issn.1000-5641.2015.05.003
    Abstract ( 1263 )   PDF (2645KB) ( 963 )   Save
    In recent years, with the rapid increase in the number of GPSenabled mobile devices, locationbased services (LBS) applications grow explosively, such as finding the nearest gas station or restaurants within one kilometer and so on. Users benefit from convenience of LBS. However, many privacy issues draw people's attention gradually. Acomprehensive understanding of existing privacy protection work in the locationbased services is important for researchers to grasp the present research status, the future development directionsand the challenges.We give a deep survey of the recent improvement in LBS,which mainly focus on existing attacking models,privacy protection model, measure model and datasets.What′s more, we classifies the existing attacking model and privacy protection model and made comparisons based on different features. Finally unsolved problems and future development are also discussed. 
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    Review on privacy protection approaches in smart meter
    TIAN Xiuxia1,LI Lisha2,SUN Chaochao1,LIU Daming1
    2015, 2015 (5):  46-60.  doi: 10.3969/j.issn.1000-5641.2015.05.004
    Abstract ( 1139 )   PDF (1844KB) ( 1040 )   Save
    With the development of the smart grid and communication technologies, smart meters have attracted increasing attentions. On the one hand, smart meters brought considerable convenience for users with better electricity consumption management and power companies′ effective power supply and efficient billing; on the other hand, it raised security threat that finegrained smart meter data could reveal users′ private information. This paper conducted a thorough survey on existing solutions mainly from identity privacy protection approach and data privacy protection approach. We deeply compared their privacyrelated factors, such as the strength of privacy protection, computational overhead, transmission overhead. Finally, we investigated the remaining challenges to protect user privacy in smart meter and discussed plausible and promising trends and directions for future research.
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    Review on trajectory data compression
    JIANG Jun-wen,WANG Xiao-ling
    2015, 2015 (5):  61-76.  doi: 10.3969/j.issn.1000-5641.2015.00.005
    Abstract ( 1671 )   PDF (2552KB) ( 1068 )   Save
    The popularity of mobile terminals and the development of GPS positioning technology produce a mass of mobile trajectory data. Based on the data, a lot of locationbased services (LBS) provide services for people. However, the increment of trajectory data brings many challenges: huge data volume, long query latency and data redundancy. Hence the trajectory compression plays an important role in providing better LBS. The purpose of trajectory compression is to minimize the size of trajectory as far as possible, which satisfies the threshold of similarity between compressed trajectory and original trajectory. This paper aims at illustrating useful trajectory compression methods, including line simplification methods, mapmatching based compression methods and semantic compression methods, and introducing query processing of compressed trajectories and trajectory management systems.
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    Privacy preserving for moving objects with transportation modes
    XU Jian-qiu,HUANG Huo-rong
    2015, 2015 (5):  77-87.  doi: 10.3969/j.issn.1000-5641.2015.05.006
    Abstract ( 955 )   PDF (2775KB) ( 828 )   Save
    The current methods of locationbased privacy preserving focus on protecting the location of users, but do not consider transportation modes such as BUS, WALK and CAR. Being one key attribute of moving objects, transportation mode reflects the feature of mobile users and can be used to analyze their behavior. This paper proposes a method including cloaking location and reset modes to preserve transportation modes of moving objects for range queries. Such a technique prevents modes from being disclosed and avoids returning precise data to illegal users. We analyze the two methods and introduce how to integrate the solution into the existing system. In addition, cloaking location and reset modes with different preserving granularity is proposed to have a flexible and tunable method for different applications.
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    Trajectory privacy preserving algorithm based on trajectory direction
    QIU Ming,PI De-chang
    2015, 2015 (5):  88-95.  doi: 10.3969/j.issn.1000-5641.2015.05.007
    Abstract ( 1073 )   PDF (2121KB) ( 881 )   Save
    A trajectory privacy preserving algorithm based on trajectory direction is proposed. In privacypreserving, dummy is an effective method that was widely used in locationbased service, but in the continuous motion of the user, the user may sends a service request to the position in any point of a track, how to make the dummy looks more realistic is a huge challenge. To solve this problem, we proposed a Trajectory Privacy Preserving Algorithm Based on Trajectory Direction (TPPATD). The middle server can generate different dummies according to different privacy requirements. So as to reduce the probability of the user trajectory being exposed. The experimental results show that, compared with the traditional method of Random Pattern Scheme, Trajectory Privacy Preserving Algorithm Based on Trajectory Direction can generate more dummies when user’s privacy requirements is higher, and dummies are more realistic with the true trajectory.
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    Finegrained privacypreserving framework while ensuring  data usability in trajectory databases
    XIONG Sheng-chao,WU Xia,PENG Zhi-yong
    2015, 2015 (5):  96-103.  doi: 10.3969/j.issn.1000-5641.2015.05.008
    Abstract ( 763 )   PDF (1667KB) ( 952 )   Save
    The privacy of trajectories has aroused a wide concern. In previous works, rarely have the differences between different sensitive locations been discussed, nor the differences between different applications (eg: for advertising and for emergencies). While in fact, some sensitive locations are more important and some applications ought to be granted the access. In this paper, to meet different privacy requirements and data utility requirements, we propose a finegrained privacypreserving framework which allows the users to specify which locations are visible to some applications and invisible to others at the same time. In addition, since most sensitive locations are relevant to stay points and a significant stay in a sensitive place may last longer than the ordinary places, we also propose an efficient approach to distribute invisible location samples along the nearby popular visit sequences. Experiment results indicate that our framework performs efficiently without introducing significant performance penalties.
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    Dynamic trajectory anonymization in location based services
    WEI Shen,SUN Guang-zhong,XIE Xing
    2015, 2015 (5):  104-115.  doi: 10.3969/j.issn.1000-5641.2015.05.009
    Abstract ( 994 )   PDF (3015KB) ( 827 )   Save
    Locationbased services in user’s mobile device can send geographical information queries to the server continuously, and receive corresponding results to the user. But simultaneously assure the quality of service and none leakage of geographical information is an important problem. This paper used a dummy location method to protect user’s real locations. The device sent multiple locations to the server. The paper also proposed a heuristic algorithm to partition location set and used δ privacy to prevent adversary infer sensitive information from contiguous locations. At last, an experiment on a WiFi access data set shows that five or six locations need to be sent averagely. 
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    Privacy preservation approach for location based service on road network
    ZHENG Miao,WANG Bin,YANG Xiao-chun
    2015, 2015 (5):  116-127.  doi: 10.3969/j.issn.1000-5641.2015.05.010
    Abstract ( 844 )   PDF (2704KB) ( 1171 )   Save
    The purpose of preserving users’ location privacy is to prevent others in any way knowing the location of the mobile users in the past or now, and provide mobile users with high quality service at the same time. On the other hand, the purpose of preserving users query privacy is to prevent others in any way knowing the query of mobile users. Privacy preservation has a unique structural characteristic on road network. In this paper, according to the characteristics of the road network, based on the network expansion method, it will form an undirected graph containing an internal ring as anonymous space for mobile users to send requests, namely it takes the small graph with a ring in the road network graph. This graph combines the structure characteristics of both ring and tree, effectively preventing anonymous space from becoming a single path and protecting the location privacy of mobile users. At the same time, this paper first proposes refine of anonymous space. Through refining, it can be determined that whether the anonymous space of mobile users in the same anonymous set is same, and whether two anonymous spaces after removing the intersection is a single path. It can effectively prevent query privacy leak because of anonymous space without mutuality.
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    Pseudorandom number encryption based location privacy preserving nearest neighbor querying
    ZHANG Feng,NI Wei-wei
    2015, 2015 (5):  128-142.  doi: 10.3969/j.issn.1000-5641.2015.05.011
    Abstract ( 1015 )   PDF (1637KB) ( 1568 )   Save
    The rapid development of positioning and mobile communication promotes the popularity of locationbased services. Nearest neighbor querying witness its thriving in locationbased services. With the increasing attention people pay to individual privacy, location privacy preserving k nearest neighbor querying becomes a hot topic. In recent years, private information retrieval techniques attract increasing concerning from researchers for its merits in providing high location protection strength, as well as its independence on any trusted thirdparty. A series of methods are proposed based on PIR to surmount the problem of location privacy protection in nearest neighbors querying. Most of them suffer from heavy time cost in preprocessing as well as query process. Concerning these problems, a novel PIR based method PRN_kNN is proposed to surmount above mentioned problems.The client can pinpoint the candidate k nearest neighbor set quickly by spatial encryption. Meanwhile, a pseudorandom number encryption schema is elaborated to avoid pattern attack and reduce the workload of preprocessing.Further, continuous storage policy for POI entity is adopted to avoid storing large amounts of fake entities in some blocks, which can enhance the efficiency of preprocessing and the querying process. Theoretical and empirical analysis demonstrate the effectiveness and efficiency of our method.
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    The LBS system based on polygonal cloaking region
    CAO Wu,XU Lyu,LIU Yu-bao,YIN Jian
    2015, 2015 (5):  143-153.  doi: 10.3969/j.issn.1000-5641.2015.05.012
    Abstract ( 1036 )   PDF (4782KB) ( 1047 )   Save
    With the broad range of application of location detected device such as mobile phone, GPS and RFID etc, the researchers have paid more and more attention to the locationbased services (LBS). Though LBS brings convenience to us, it also rises up the risk of location privacy leakages. The existing LBS systems transform the users’ locaiton into a rectangle or circle cloaking region by location generalization. Then, the users’ location can be hidden in the cloaking region to achieve the purpose of protecting the users’ locaiton privacy. However, in practical applications, the cloaking region may be related to the actual landform for the users’ location, it may not be a rectangle or circle region. In fact, a rectangle or circle region even may result in the increase of invalid region and reduce the location information accuracy. In this paper, based on the shortcoming of existing systems, we design and implement a new system in which the user can define the polygonal cloaking region based on actual landform. At the meantime, the system can provide a double protection for the users’ location privacy. The system performance tests show the effectiveness of the propsed system.
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    A privacy preserving framework  for efficient computation of trajectory similarity
    LIU Shushu,LIU An,LIU Guanfeng,LI Zhixu,ZHAO Lei,ZHENG Kai
    2015, 2015 (5):  154-161.  doi: 10.3969/j.issn.1000-5641.2015.05.013
    Abstract ( 1115 )   PDF (2779KB) ( 889 )   Save
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    An urban population flow analysis system based on mobile big data
    Bao Ting, Zhang Zhi-gang, Jin Che-qing
    2015, 2015 (5):  162-171.  doi: 10.3969/j.issn.1000-5641.2015.05.014
    Abstract ( 1177 )   PDF (2567KB) ( 2125 )   Save
    Analysis on urban population flow can help to make rational distribution of social resources, cope with traffic pressure and maintain public order, etc. The traditional manual analysis methods, such as questionnaire and interview, can not deal with this task efficiently. The continuous development and prevalence of smart phones bring great convenience to people′s daily life and users′ trajectory data generated by the connection between smart phones and base stations, which makes it possible to implement this task. However, trajectory data is massive and has low quality, which brings great challenge to related work. We propose a distributed framework for population flow analysis by using multiple computing nodes, thus greatly enhancing efficiency and scalability. In this paper, we use the massive trajectory data to analyze the behavior of urban population flow. We model flowing behavior among cities and among innercity districts, and decide the work place and living place of each person. Compared with the traditional methods, our method is cheaper and more efficient.
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    High availability implementation based on Raft
    ZHANG Chen-dong,GUO Jin-wei,LIU Bo-zhong,CHU Jia-jia,ZHOU Min-qi,QIAN Wei-ning
    2015, 2015 (5):  172.  doi: 10.3969/j.issn.1000-5641.2015.05.015
    Abstract ( 1709 )   PDF (3704KB) ( 1326 )   Save
    With the rapid development of Internet and the upcoming Big Data era, the limitation of traditional database has been emerged and enlarged. The distributed database system based on massive data storage and high concurrent accesses has become more and more popular. Alibaba group developed a distributed database system suitable for mass data storage named OceanBase, which supports two deployment modes, i.e.〖KG-*3〗, single cluster and multiple clusters. But the availability of multiple clusters mode is not efficient and can’t satisfy the requirement of some critical applications, where it does not support the automatic switch between master cluster and slave cluster when a failure occurred and the inconsistent log is also generated during switching under multiple clusters mode. To address these problems, we analysis the high availability solutions of the traditional database,aiming at the characteristics of OceanBase architecture, combining the idea of in Raft, and then designs and implements the distributed election module based on the timestamp of logs, the automatic clusters switching module and the strong synchronization logs module based on QUORUM.The experimental results showed that the above approachescould improve the availability of the whole system.
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