DDRP中的虫洞攻击分析与预防

定向扩散路由协议极易遭受虫洞攻击。为此,以仅存在2个毒害节点的情况为例,推导毒害节点放置位置与虫洞攻击严重程度间的定量关系。通过OMNeT++上的仿真实验,求解毒害节点最佳放置位置,并说明对应的最大虫洞攻击严重程度。为预防虫洞攻击,提出一种将最佳梯度节点加强转换为梯度节点概率选择加强的策略。仿真实验结果表明,该预防策略是有效的。     

蠕虫算法在并行数字信号处理系统中的应用

本文蠕虫算法在并行数字信号处理的应用作了较详尽的讨论,主要阐述了蠕虫算法实现的两个过程,命名过程和探测算法,并给出了在SHARC处理器构成的并行处理网络中实现的结果,其结果证明本文描述的算法是正确有效的,它对其它类似的并行数字信号处理系统中蠕虫算法的实现有启示作用。     

Adaptive Multimodule Routers for Multiprocessor Architectures

Recent multiprocessors such as Cray T3D support interprocessor communication using partitioned dimension-order routers (PDRs). In a PDR implementation, the routing logic and switching hardware is partitioned into multiple modules, with each module suitable for implementation as a chip. This paper proposes a method to incorporate adaptivity into such routers with simple changes to the router structure and logic. We show that with as few as two virtual channels per physical channel, adaptivity can be provided to handle nonuniform traffic in multidimensional meshes.     

移动Ad Hoc网络安全按需路由协议

Ad Hoc网络的安全性问题越来越引起人们的关注,如何确保Ad Hoc网络路由协议的安全成为Ad Hoc研究的一项关键技术。提出一种适用于移动Ad Hoc网络的安全按需源路由协议,利用移动节点之间的会话密钥和基于散列函数的消息鉴别码HMAC一起来验证路由发现和路由应答的有效性。提出的邻居节点维护机制通过把MAC地址和每个节点的ID绑定来防御各种复杂的攻击如虫洞攻击。NS-2仿真表明该协议能有效地探测和阻止针对Ad Hoc网络的大部分攻击。     

Experimental and modelling study of the solubility of CO2 in various CaCl2 solutions at different temperatures and pressures

Study of the thermodynamic behaviour of CaCl2-H2O-CO2 systems is important in different scientific areas in the chemical and petroleum engineering fields. For example, a system including salt- H20-CO2 is a common system in CO2 geological storage. During carbonate matrix acidizing, this mixture also appears as the spent acid. Hence, study of the behaviour of this system and the solubility of CO2 in CaCl2 brine in different thermodynamic conditions is critical. In this study, CO2 solubility in 0, 1.90 and 4.80 mol/L CaCl2 solutions at 328.15 to 375.15 K and 68.9 to 206.8 bar were measured. These values are normal for oil reservoirs. A popular thermodynamic model is available in the literature for estimating the CO2 solubility in pure water and NaC1 solutions. In this paper, the available model was modified by experimental work to be applicable for CaCl2 as well. Based on the measured data, the component interaction parameters in the base model were adjusted for a CaCl2-H2O-CO2 system. The developed model could predict CO2 solubility in different conditions with remarkable accuracy, particularly for high concentration solutions and at high pressures. This improvement is up to 65% better than in the base model. This model can be used in Darcy scale models for predicting wormhole propagation during carbonate matrix acidizing.     

衬管完井水平井新型布酸技术研究与应用——以安岳气田磨溪构造龙王庙组气藏为例

衬管完井具有泄流面积大、完井成本低等优势,目前成为水平井完井的主要方式之一。衬管完井水平井酸化改造的关键是如何实现水平井段上的均匀布酸,但由于割缝衬管与岩石壁面之间环形空间未真正封隔,常规分段工艺的应用受到限制,致使衬管完井水平井均匀布酸困难。为此,通过理论研究和室内实验评价,形成了衬管完井水平井新型均匀布酸技术：①预测水平井段上初始表皮系数分布剖面,明确不同井段损害分布特征;②建立水平井段上酸液流量数学模型,模拟计算不同井段暂堵转向净压力值;③优化设计不同井段衬管割缝参数,优选转向剂加量,实现井底不同转向净压力;④采用数值刻画方法定量表征酸蚀蚓孔形态,优选适合的酸液体系。在安岳气田现场应用8口井,井均增产倍比达1.95,井均增加测试产量67.3×104m3/d,相比射孔完井,单井节约完井成本900万元,对同类型气藏衬管完井水平井均匀布酸技术具有借鉴意义。     

无线传感网络中抵御虫洞攻击的基于统计估计的新型位置方案

Wormhole attack is one of the most devastating threats for range-free localization in wireless sensor networks. In this paper, we evaluate three statistical estimation methods with the same network model and geographic information obtained by the DV-Hop algorithm. We analyze the limits of Minimum Mean Square Estimate (MMSE), Least Median of Squares (LMS) and Enhanced greedy Attack-Resistant MMSE (EARMMSE) and propose an improved EARMMSE with the hop-distance relationship, named EARMMSE +. Simulation results illustrate the performance of MMSE, LMS and EARMMSE +with different anchor fraction, the length of wormhole link and the average local neighborhood and show that EARMMSE +outperforms MMSE and LMS.     

Mitigation of colluding route falsification attacks by insider nodes in mobile ad hoc networks

Colluding malicious insider nodes with no special hardware capability can use packet encapsulation and tunneling to create bogus shortcuts (in‐band wormholes) in routing paths and influence data traffic to flow through them. This is a particularly hard attack using which even a handful of malicious nodes can conduct data traffic analysis of packets or disrupt connections by dropping packets when needed. Simulation analysis shows that a disproportionately large amount of traffic goes through routes with wormholes even when a secure routing protocol (SRP) such as Ariadne is used. To mitigate such attacks and augment existing on demand SRPs, distributed packet filtering techniques based on statistical profiling of control packet propagation speeds are proposed. These techniques do not require network‐wide synchronized clocks or new packet transmissions and need only simple computations by the sources or the destinations of the connections. The proposed packet filters together with Ariadne are implemented in the Glomosim simulator and their effectiveness is evaluated. The simulation results indicate that the proposed packet filters can reduce the in‐band wormhole creation and their usage by a factor of 2‐‐10. Also, the false alarm rates of the proposed techniques are very low and have little impact on normal network throughput, making them practical for mobile ad hoc networks. Copyright © 2008 John Wiley & Sons, Ltd.     

无线传感器网络中的虫洞攻击和防御

无线传感器网络被誉为21世纪三大技术之一,其安全问题受到了越来越多的关注.文章首先介绍了无线传感器网络的特征,分析了安全问题的根源,然后详细介绍了无线传感器网络中虫洞攻击的原理和破坏性,提出引入简化的marsh信任模型,将邻居节点以往表现作为信任评估的经验来源,通过具体分析确定节点的位置关系,从而避免传感器网络中的虫洞攻击,最后指出了下一步研究的方向.     

A Performance Model of Adaptive Wormhole Routing in k-Ary n-Cubes in the Presence of Digit-Reversal Traffic

Several analytical models of fully adaptive routing in wormhole-routed k-ary n-cubes under the uniform traffic pattern have recently been proposed in the literature. Although the uniform reference model has been widely used by researchers, it is not always true in practice as there are many applications that exhibit traffic nonuniformity. There has hardly been any study that describes an analytical model of fully adaptive routing under nonuniform traffic conditions. This paper describes the first analytical model of fully adaptive routing in k-ary n-cubes in the presence of nonuniform traffic generated by the digit-reversal permutation, which is an important communication operation found in many matrix computation problems. Results obtained through simulation experiments confirm that the model predicts message latency with a good degree of accuracy under different working conditions.