Group-Based Trust Management Scheme for Clustered Wireless Sensor Networks

Traditional trust management schemes developed for wired and wireless ad hoc networks are not well suited for sensor networks due to their higher consumption of resources such as memory and power. In this work, we propose a new lightweight group-based trust management scheme (GTMS) for wireless sensor networks, which employs clustering. Our approach reduces the cost of trust evaluation. Also, theoretical as well as simulation results show that our scheme demands less memory, energy, and communication overheads as compared to the current state-of-the-art trust management schemes and it is more suitable for large-scale sensor networks. Furthermore, GTMS also enables us to detect and prevent malicious, selfish, and faulty nodes.     

TRIP,a trust and reputation infrastructure-based proposal for vehicular ad hoc networks

Vehicular ad hoc networks (VANETs) have drawn the attention of a number of researchers due to their several advantages and benefits. It is a very promising area of knowledge where investing new funds and effort is surely a wise move. Nevertheless, despite their multiple capabilities, new unresolved risks arise, and it is not always easy, or even feasible to cope with them. Recently, trust and reputation management has been proposed as a novel and accurate way to deal with some of these deficiencies. A considerable amount of works have been developed so far in this field concerning P2P networks, wireless sensor networks, ad hoc networks, etc. However, the application of behavioral-based trust and reputation management to VANETs is still at a preliminary stage. In this paper we survey the sate of the art, proving the current lack of proposals in this specific environment. We also suggest a set of design requirements for trust and reputation models specifically applicable to VANETs. Furthermore, we present our original proposal, TRIP, aimed to quickly and accurately distinguish malicious or selfish nodes spreading false or bogus messages throughout the network. We have also studied the level of fulfillment of each of the surveyed models with regard to each design requirement suggestion, comparing them with our approach. Finally, some preliminary experiments demonstrate the accurate performance of our trust and reputation mechanism under several different conditions.     

基于区块链的车联网信任机制

车联网（VANETs）中虚假的共享信息会导致负面影响。针对车辆间的信任缺失现象,提出了一种基于区块链的信任解决方案。通过引入贝叶斯推理,基于先验概率进行信任评估,综合考虑了消息可信度和源节点自身可信度。通过超级账本实现信任管理,路侧单元（RSU）将汇聚车辆提交的评价形成信任值并创建区块,利用智能合约进行信任值初始化、查询和更新操作。仿真结果显示,提出方案能有效进行信任评估,准确识别虚假消息。同时与现有方案对比表明,该方案具有更高吞吐量和更低时延,适用于车联网的轻量级资源消耗环境。     

Voting as the optimal static pessimistic scheme for managingreplicated data

This paper investigates the problem of finding an optimal static pessimistic replica control scheme. It has been widely accepted that coteries (proposed by Garcia-Molina and Barbara) provide the most general framework for such schemes. We demonstrate that voting schemes, a very small subset of static pessimistic schemes, are optimal for fully connected networks with negligible link failure rates, as well as for Ethernet systems. We also show that voting is not optimal for somewhat more general systems. We propose a modification of the algorithm of Z. Tong and R.Y. Kain (1988) for computing optimal voting in operation independent case, so that it runs in linear (rather than exponential) time. Finally, we propose the first efficient algorithm for computing the optimal vote assignment and appropriate thresholds for fully connected networks when relative frequencies of read and write operations are known. We also extend this result to Ethernet systems     

Analytical evaluation of average delay and maximum stable throughput along a typical two-way street for vehicular ad hoc networks in sparse situations

Intermittent connectivity is an intrinsic feature of vehicular ad hoc networks (VANETs) in sparse situations. This type of network is in fact an example of delay and disruption tolerant networks (DTNs). In this paper, we focus on a typical two-way street and analytically evaluate the maximum stable throughput and the average delay for packet forwarding along the street. To this end, we map the mobility patterns of the vehicles with different speeds onto suitable parameters of a BCMP queueing network and derive the location density of vehicles. Then, we employ another queueing network in order to model opportunistic multi-hop packet forwarding along the street with respect to the specifications of MAC and routing schemes. We propose a two-mode MAC scheme suitable for DTNs with predictable mobility patterns. We also consider the effect of vehicles’ velocities and opportunistic relaying for routing schemes. In our analysis, we evaluate the average delay and the maximum stable throughput for the proposed MAC and routing schemes. In the last part of the paper, we show the efficiency of the proposed analytical approach by some numerical results and confirm our analysis by simulation.     

基于路径上报的车联网轨迹隐私保护

车载自组织网络(vehicular ad hoc networks, VANETs)(也称车联网)数据收集与应用为智能交通、城市规划、降低车辆污染等问题提供有效的技术和数据保障. 在车联网数据收集中通常需要车载用户上报连续路段位置信息,这给车载用户个人轨迹隐私带来严重的威胁. 然而现有用户轨迹保护算法主要基于单点位置保护,不能有效保护基于路径上报的用户轨迹隐私.针对车联网中用户移动轨迹易泄露问题,提出一种基于路径隐私保护的位置信息上报方案. 该方案给出用户轨迹隐私保护定义和路径隐私限制下的问题模型,同时证明了该问题是NP-hard问题. 此外,还给出该问题的具体近似算法的实现. 仿真实验结果表明：提出的算法具有良好的车载用户隐私保护功能和数据收集覆盖性能.     

一种能量有效的平面式无线传感器网络的信任管理模型

信任管理机制解决了来自无线传感器网络的内部攻击问题,但同时产生由信任评价带来的额外开销。现有的信任管理模型对节点信任度的评价缺乏公平性,导致节点使用率的降低。为了解决信任机制在无线传感器网络的耗能问题,提出了一种能量有效的平面式无线传感器网络信任模型。通过节点的自身性能与任务难度的关系定义节点的执行度,在确保信任管理有效性的同时,增强节点信任度评价的公平性,从而提高传感器节点的使用率,降低了能量消耗。最后通过模拟实验,证明该信任模型与传统信任模型相比,能够有效检测恶意节点,同时大大降低了节点的能量消耗,提高了网络生存周期。     

Trust-based security for wireless ad hoc and sensor networks

Wireless sensors networks are susceptible to a large number of security threats, and because of the communication, computation and delay constraints of most applications that run on top of these networks, traditional security mechanisms cannot be used. Trust and reputation have been recently suggested as an effective security mechanism for open environments such as the Internet, and considerable research has been done on modeling and managing trust and reputation. Using the trust and reputation management scheme to secure wireless sensor networks (WSNs) requires paying close attention to the incurred bandwidth and delay overhead, which have thus far been overlooked by most research work. In this paper, we propose a novel agent-based trust and reputation management scheme (ATRM) for wireless sensor networks. The objective of the scheme is to manage trust and reputation locally with minimal overhead in terms of extra messages and time delay. Throughout the entirety of this paper, we describe our scheme and prove its correctness. We will also present our extensive performance evaluation results, which clearly show that trust and reputation can be computed in wireless sensor networks with minimal overhead.     

New receipt-free voting scheme using double-trapdoor commitment

It is considered to be the most suitable solution for large scale elections to design an electronic voting scheme using blind signatures and anonymous channels. Based on this framework, Okamoto first proposed a receipt-free voting scheme [30] for large scale elections. However, in the following paper, Okamoto [31] proved that the scheme [30] was not receipt-free and presented two improved schemes. One scheme requires the help of the parameter registration committee and the other needs a stronger physical assumption of the voting booth. In this paper, we utilize the double-trapdoor commitment to propose a new receipt-free voting scheme based on blind signatures for large scale elections. Neither the parameter registration committee nor the voting booth is required in our scheme. We also present a more efficient zero-knowledge proof for secret permutation. Therefore, our scheme is much more efficient than Okamoto’s schemes [30] and [31] with the weaker physical assumptions. Moreover, we prove that our scheme can achieve the desired security properties.     

车联网中beacon消息传输频率研究

车联网(VANETs)提供车与车之间的车间通信(V2V)和车与路旁设施(V2I)间的通信.VANETs中存在两类消息:beacon消息和安全消息.车辆周期地交互车辆的beacon消息,仅在紧急情况下才广播安全消息;而beacon消息的传输频率受多个因素影响.为此,提出基于模糊逻辑的自适应beacon传输频率方案,利用模...     

A grid-based dynamic load balancing approach for data-centric storage in wireless sensor networks

In many data-centric storage techniques, each event corresponds to a hashing location by event type. However, most of them fail to deal with storage memory space due to high percentage of the load is assigned to a relatively small portion of the sensor nodes. Hence, these nodes may fail to deal with the storage of the sensor nodes effectively. To solve the problem, we propose a grid-based dynamic load balancing approach for data-centric storage in sensor networks that relies on two schemes: (1) a cover-up scheme to deal with a problem of a storage node whose memory space is depleted. This scheme can adjust the number of storage nodes dynamically; (2) the multi-threshold levels to achieve load balancing in each grid and all nodes get load balancing. Simulations have shown that our scheme can enhance the quality of data and avoid hotspot of the storage while there are a vast number of the events in a sensor network.     

An efficient key management scheme for user access control in outsourced databases

Recently, researches on key management scheme for user access control in outsourced databases have been actively done. Because outsourced databases require dealing with a lot of users and data resources, an efficient key management scheme for reducing the number of authentication keys is required. However, the existing schemes have a critical problem that the cost of key management is rapidly increasing as the number of keys becomes larger. To solve the problem, we propose an efficient key management scheme for user access control in outsourced databases. For this, we propose an Resource Set Tree(RST)-based key generation algorithm to reduce key generation cost by merging duplicated data resources. In addition, we propose a hierarchical Chinese Remainder Theorem(CRT)-based key assignment algorithm which can verify a user permission to gain accesses to outsourced databases. Our algorithm can reduce key update cost because the redistribution of authentication keys is not required. We also provide the analytic cost models of our algorithms and verify the correctness of the theoretical analysis by comparing them with experiment results. Finally, we show from the performance analysis that the proposed scheme outperforms the existing schemes in terms of both key generation cost and update cost.     

车载自组网中一种支持群签名认证的分布式密钥管理方案

群签名具备良好的匿名认证特性,满足车载自组网信息安全和隐私保护需求。但是,其作废开销较大,不适于在大规模网络环境中应用。为此,本文提出了一种支持群签名认证的分布式密钥管理方案DKM,将车载自组网的覆盖区域划分为若干子区域,车辆周期性地从所在子区域的群管理机构更新群密钥。这样,作废某个成员只需要在其拥有合法密钥的子区域内通告,而不是整个网络,有利于降低作废开销。同时,DKM中的密钥更新机制能够保证车辆的群密钥的私密性,从而避免了车辆与区域群管理机构的授权争议,保持了数字签名的不可否认性。性能分析表明DKM能够显著缩短作废列表长度,同时没有增加认证开销。     

A soft computing approach to localization in wireless sensor networks

In this paper, we propose two intelligent localization schemes for wireless sensor networks (WSNs). The two schemes introduced in this paper exhibit range-free localization, which utilize the received signal strength (RSS) from the anchor nodes. Soft computing plays a crucial role in both schemes. In the first scheme, we consider the edge weight of each anchor node separately and combine them to compute the location of sensor nodes. The edge weights are modeled by the fuzzy logic system (FLS) and optimized by the genetic algorithm (GA). In the second scheme, we consider the localization as a single problem and approximate the entire sensor location mapping from the anchor node signals by a neural network (NN). The simulation and experimental results demonstrate the effectiveness of the proposed schemes by comparing them with the previous methods.     

Cooperative pseudonym change scheme based on the number of neighbors in VANETs

In Vehicular Ad hoc NETworks (VANETs), trigger-based pseudonym change schemes play an important role in providing anonymity. However, the anonymity provided by these schemes usually is low mainly because the behavior of changing pseudonym is individual. Considering cooperation on changing pseudonym can enhance anonymity, in this paper, we give a general cooperation framework. As an application of the framework, we present a Cooperative Pseudonym change scheme based on the number of Neighbors (CPN). We generally analyze the anonymity provided by the CPN scheme and qualitatively compare the scheme with its corresponding scheme without cooperation, Non-CPN (NCPN). Then, under uniform traffic distribution, we develop an approximate analytical model for CPN in relatively simple one-lane VANETs to analyze the anonymity. Finally, we investigate the anonymity of CPN in one-lane and multi-lane VANETs by simulation. The results show that the ratio of the size of anonymity set in multi-lane to that in one-lane VANETs, first quickly goes up, then slowly decreases a bit, and at last approaches the value of number of lanes. In addition, the improved performance of CPN over NCPN reaches peak when the average number of neighbors approaches that number in the trigger.     

Comparison of recovery schemes to maximize restorable throughput in multicast networks

Multicast networks have many applications especially in real-time content delivery systems. For high-quality services, users do not expect to witness any interruption; thus, network link failure has to be handled gracefully. In unicast networks there are many approaches for dealing with link failures using backup paths. Recently, Cohen and Nakibly categorized these methods, provided linear programming formulations for optimizing network throughput under the assumption that the paths are splitable, and compared them experimentally. In this work, we take their approach and apply to the multicast failure recovery problem. We propose backup bandwidth allocation algorithms based on linear programs to maximize the throughput, and perform an experimental study on the performance of recovery schemes. We study many recovery schemes in multicast networks and propose a new recovery scheme that performs better than all other recovery scheme except the one that recomputed the whole multicast tree from scratch for each link failure.     

A survey on trust based detection and isolation of malicious nodes in ad-hoc and sensor networks

Mobile ad-hoc networks (MANETs) and wireless sensor networks (WSNs) have gained remarkable appreciation and technological development over the last few years. Despite ease of deployment, tremendous applications and significant advantages, security has always been a challenging issue due to the nature of environments in which nodes operate. Nodes’ physical capture, malicious or selfish behavior cannot be detected by traditional security schemes. Trust and reputation based approaches have gained global recognition in providing additional means of security for decision making in sensor and ad-hoc networks. This paper provides an extensive literature review of trust and reputation based models both in sensor and ad-hoc networks. Based on the mechanism of trust establishment, we categorize the stateof-the-art into two groups namely node-centric trust models and system-centric trust models. Based on trust evidence, initialization, computation, propagation and weight assignments, we evaluate the efficacy of the existing schemes. Finally, we conclude our discussion with identification of some unresolved issues in pursuit of trust and reputation management.     

自计票电子投票方案的分析与改进

Kiayias和Yung首次提出了自计票电子投票方案,使得小规模电子选举不需要任何可信第三方参与,选举的行为公开可验证,有力地保证了选举的秘密性,Groth在此基础上做了改进,使得方案更简洁、高效;然而Groth方案仍只用于双候选人选举,且不允许两个选民同时投票.简要介绍并分析了Groth方案,针对上述两点不足给出改进建议,使新方案更高效且用于多候选人选举.     

Utility-based downlink power allocation in multicell wireless packet networks

This paper introduces a utility-based radio resource management technique in multicell wireless packet networks. In terms of allocation of base station (BS) downlink transmit power and assignment of resource to users in each cell, we formulate a problem of maximizing system utility which is defined as the sum of cell utilities. The problem, however, is not solvable due to its non-convex property. Thus, we propose a heuristic algorithm based on an intuition obtained from analyzing a simple two-cell problem. Though the heuristic approach also incurs signaling overhead for power coordination between neighboring base stations, it is much less than that of the original approach. Simulation results show the performance of our proposed algorithm compared with two competitive schemes: optimal and maximum power allocation schemes. As expected, the optimal allocation scheme shows the best performance but can not be employed in a real network due to intractable complexity. Our heuristic algorithm performs reasonably well with very low complexity.