安全的网络编码所面临的挑战和对策

近年来,网络编码以其巧妙的思想展现出生机勃勃的应用前景,但是安全问题一直是其在网络中大规模应用的最大障碍。在现有研究成果上,从网络编码的基本原理出发,按照物理层和网络层两个层面对系统的各个部分进行了更加全方位的安全隐患分析;也给出了针对ACK类和编码类攻击的基于典型集和哈希函数以及马尔可夫模型的防御方法;同时提出了结合利用云计算和网络编码构建计算网络的概念;最后对网络编码的未来研究方向进行了展望。     

基于网络编码的ECC验证方案在WSN中的研究

网络编码在无线传感器网络应用,改善了无线传感器网络的性能。虽然与之前相比,其安全性有所提高,但当面临安全攻击（被动攻击和主动攻击）时,整个网络系统的安全性仍然亟待提高。提出了一种改进方案,该方案结合密码学中椭圆曲线加密算法,并基于应用网络编码的无线传感器网络,采用加密验证方案。使传感器节点在电量受限的情况下,传输更多的有效数据。同时,增强了无线传感器网络节点之间通信的安全性,以及WSN其鲁棒性和容错性。     

一种安全的多源网络编码签名算法

网络编码已被证明在提高网络传输速率、减少网络拥塞、增强网络可靠性以及降低结点能耗等方面有着巨大优势,因此可被广泛用于计算机网络、无线传感器网络以及p2p系统中。但是,网络编码也面临着多方面的安全威胁,其中污染攻击是其最主要的安全威胁之一。目前,绝大部分的签名方案均只能适用于对单源网络编码中的污染攻击,无法满足普遍存在的多源网络编码的安全要求。对多源网络编码中的污染攻击进行了更深入的分析,给出了安全的多源网络编码所需要满足的条件,提出了一个安全高效的多源网络编码签名算法来预防网络中的污染攻击,该算法可以满足多源网络编码的全部安全要求。     

基于网络编码的无线数据流保护

网络编码是一种能显著提升网络传输性能的通信机制。而当前将网络编码应用于无线数据流保护以提高网络生存能力方面的研究还没达到如此完备的程度。本论文旨在建立基于网络编码的无线数据流保护模型,验证并实现建立进行网络编码的网络拓扑的算法。验证网络编码应用于无线数据流保护可以提高网络生存能力、减少网络资源消耗并具有远胜于传统保护的时效优势。在网络中部署和实施网络编码,必须建立适用于网络编码的传输节点拓扑并选择合适的编码模式。对于后者,许多学者出了有效的解决方法,而对于网络拓扑规划问题的研究则相对较少。鉴于此,本文论证了一种编码树拓扑结构算法,该算法与现有的编码模式一起,能够构成完整的网络编码无线数据流保护方案。通过理论论证可以证明应用网络编码方法可以在保护时节约网络资源。仿真实验表明,与传统的链路保护模式相比,使用网络编码的无线数据流保护方法具有更小的时延,也即具有传统保护方法没有的时间优势。     

An efficient ECC-based mechanism for securing network coding-based P2P content distribution

Network coding has been demonstrated to be able to improve the performance of P2P content distribution. However, it is vulnerable to pollution attacks where malicious peers can flood the network with corrupted blocks easily, leading to substantial performance degradation. Moreover, existing corruption detection schemes for network coding are not well suited to P2P systems. Effective scheme to detect the corruption and identify the attacker is required to thwart such attacks. In this paper, we propose an efficient ECC-based mechanism for securing network coding-based P2P content distribution, namely ESNC, which includes an efficient network coding signature scheme and an identity-based malicious peer identification scheme. The two schemes cooperate to thwart pollution attacks on network coding effectively in P2P networks, not only detecting corrupted blocks on-the-fly efficiently, but also precisely identifying all the malicious peers quickly. ESNC is mainly based on elliptic curve cryptography (ECC) and can provide high level of security. It incurs significantly less computation and communication overheads than other comparable state-of-the-art schemes for P2P systems. ESNC can work with arbitrary topologies, as it is the case in P2P networks. Security analysis demonstrates that ESNC can resist hash collision attacks, signature forgery attacks, and collusion attacks with arbitrary number of colluding malicious peers. Simulation results show that ESNC effectively limits the corruption spread and identifies all the malicious peers in a short time under different practical settings.     

网络编码的研究进展

网络编码允许网络节点在传统数据转发的基础上参与数据处理,已成为提高网络吞吐量、鲁棒性和安全性的有效方法.在介绍网络编码基本原理的基础上,比较了集中式和分布式网络编码构造方法的优缺点,并对实用网络编码设计中涉及的同步、纠错、编解码速度等问题进行了评述;进而,对网络编码在无线网络、P2P系统、分布式文件存储和网络安全等领域的最新应用进行了总结;最后对网络编码的理论和应用研究的发展趋势进行了分析与展望.设计简单高效的实现机制,并与其他领域的技术如信道编码与调制、路由算法、队列调度以及流媒体技术等的结合,将是网络编码发展的一个重要趋势.     

Robustness Analysis and Enhancement of MANETs Using Human Mobility Traces

Understanding network behavior that undergoes challenges is essential to constructing a resilient and survivable network. Due to the mobility and wireless channel properties, it is more difficult to model and analyze mobile ad hoc networks under various challenges. In this paper, we provide a model to assess the vulnerability of mobile ad hoc networks in face of malicious attacks. We analyze comprehensive graph-theoretical properties and network performance of the dynamic networks under attacks against the critical nodes using real-world mobility traces. Motivated by minimum spanning tree and small-world networks, we propose a network enhancement strategy by adding long-range links. We compare the performance of different enhancement strategies by evaluating a list of robustness measures. Our study provides insights into the design and construction of resilient and survivable mobile ad hoc networks.     

基于网络编码的分布式无线光网络在线优化

最近, 一种集成骨干光传输网络、无源光网络和无线接入网的混合宽带无线光网络被提出。这种网络具有大带宽、低费用和无处不在的信息接入等特点。考虑在这种网络中的基于网络编码的多播会话的设计问题, 使得网络效用最大化, 而布网的费用最小化。这个问题被转换为一个混合的整数非线性规划问题, 精确求解极其困难。为了使得问题简化, 采用了一种两步优化方法进行求解, 交替地为多播会话选择光网络单元和网关。在每一次迭代过程中需要解决两个问题：光网络的网络编码设计问题和无线网络的用户和带宽分配问题。前者通过基于拉格朗日对偶分解的分布式方法实现; 后者通过广义Benders分解实现。通过仿真验证了所采用的方法的有效性。     

无线网状网中自适应网络编码的MPTCP研究与设计

网络编码可以提高无线网状网的吞吐量,但是它在无线网状网中的实际应用是一个挑战性的问题。网络编码必须和TCP很好相容才能得到广泛应用。根据无线网状网的特点,研究和设计了一种自适应网络编码的多路径TCP。在提出的方案中,网络编码被加入到现有的网络系统,源节点根据目的节点编码数据块的自由度,调整发送编码的数据块,以降低多路径传输的数据报文的失序,提高网络的吞吐量,保证各个数据流之间的公平性。仿真结果表明设计的MPTCP有效。     

无线Mesh网中网络编码节点选取分析

无线Mesh网可以使用网络编码技术显著提高多跳链路的传输性能。但网络编码是有代价的,如何选择编码节点以减少网络编码的代价是研究的重点。对无线Mcsh网中的网络编码节点的选取进行了讨论,提出了一种基于超关键节点的网络编码节点选取算法。该算法是在Ford-Fulkerson标号算法找增广链的时候,统计路径上的每个节点的入度,并在节点上保存从不同输入链路获得的信息,从而确定哪些是超关键节点,这些超关键节点将是编码节点。仿真实验表明,在实现组播最大流的前提下,该算法能有效减少网络编码的节点数。     

融合网络编码的无线协作中继网络资源分配

综述融合网络编码的无线协作中继网络资源分配的研究进展,总结了已有典型资源分配策略的特点、性能及系统设计要求,分析了网络编码技术(包括数字网络编码和物理层网络编码)的引入对无线协作中继网络资源分配策略设计的影响,给出了一种实用化的系统级跨层优化框架及设计基本原则,并探讨了无线协作中继网络资源分配研究的发展趋势及其走向实用化所亟待解决的关键问题.     

网络编码中的优化问题研究

简要回顾了网络编码的理论研究,阐述了网络编码优化问题研究的重要意义.在介绍网络信息流模型的基础上,针对优化问题的陈述、特点和解法,结合最新的研究成果进行了综述.根据优化目标的不同,优化问题可分成4类:最小花费组播,无向网络的最大吞吐率,最小编码节点、编码边,基于网络编码的网络拓扑设计.归纳了问题的求解性质,对其中的(线性或凸)规划问题总结了求解的一般方法,对NP完全问题讨论了最新的启发式算法及其设计难点.同时,展望了未来的发展方向.     

无线Ad hoc网络中基于网络编码的数据广播协议*

针对节点随机分布的无线Ad hoc网络中数据广播风暴问题,设计了一种基于网络编码的数据广播协议ENCBP。ENCBP采用了渐进式随机线性网络编码技术、自适应概率转发机制以及随机延迟发送机制。NS2仿真结果表明,与现有数据广播协议相比,该协议改善了投递率和传输延迟,协议开销较小。     

Fundamental limits on end-to-end throughput of network coding in multi-rate and multicast wireless networks

This paper investigates the interaction between network coding and link-layer transmission rate diversity in multi-hop wireless networks. By appropriately mixing data packets at intermediate nodes, network coding allows a single multicast flow to achieve higher throughput to a set of receivers. Broadcast applications can also exploit link-layer rate diversity, whereby individual nodes can transmit at faster rates at the expense of corresponding smaller coverage area. We first demonstrate how combining rate-diversity with network coding can provide a larger capacity for data dissemination of a single multicast flow, and how consideration of rate diversity is critical for maximizing system throughput. Next we address the following question: given a specific topology of wireless nodes, what is the maximum rate that can be supported by the resultant network exploiting both network coding and multi-rate? We present a linear programming model to compute the maximal throughput that a multicast application can achieve with network coding in a rate-diverse wireless network. We also present analytical results where we observe noticeably better throughput than traditional routing. This suggests there is opportunity for achieving higher throughput by combining network coding and multi-rate diversity.     

FEC-based AP downlink transmission schemes for multiple flows: Combining the reliability and throughput enhancement of intra- and inter-flow coding

We consider downlink access point (AP) networks and the corresponding reliable transmission schemes. It is well known that one can protect the network traffic against packet erasures by forward-error-correcting-codes (FEC). In addition to ensuring reliable delivery, FECs could substantially reduce the amount of feedback traffic, which is critical when designing high-performance AP protocols.In this work, we generalize the FEC-based schemes, also known as intra-flow coding schemes, for multiple downlink flows. In contrast with the classic approach that performs FEC separately on individual flows, we propose a new protocol MU-FEC, which incorporates the recent idea of inter-flow coding to further enhance the achievable throughput. Specifically, MU-FEC guarantees 100% reliability, is oblivious and robust to the underlying erasure probabilities, has near-optimal throughput higher than any existing inter-flow coding protocols, and can be practically implemented on top of 802.11. The design of MU-FEC consists of three components: batch-based operations, a systematic phase-based network coding decision policy, and smooth integration of inter-flow and intra-flow coding. We analytically show that MU-FEC can achieve much higher throughput than intra- or inter-flow coding alone, and validate its performance gain via extensive simulations. To our knowledge, MU-FEC is the first practical protocol that leverages both intra-flow and inter-flow network coding to solve a real-world problem in single-hop wireless networks.     

无线网络编码的块时延控制

网络编码技术的应用能提高无线分组网络的传输可靠性、吞吐量。但是,在这些网络编码策略中首先要将传输的信息拆分成若干个"数据块",然后再分别对各个数据块进行网络编码处理。而数据块的大小会严重影响数据块的传输时间,数据块越大,数据块时延就会随之增大。在现有的网络编码策略中,数据块的大小一般会在传输之前就会确定,但很难用事先设置好的大小满足实际情况下的时延要求。本文提出了网络编码条件下的数据块大小选择算法的目标方程,并分析了数据块大小对吞吐率的相应影响,进而设计了一种自适应满足实时应用时延要求的数据块大小的选择算法。该算法可通过在无线网络中自适应设置每一个编码块大小来满足实时应用的要求。     

无线传感器网络攻击与防范

相对于普通计算机网络来说,无线传感器网络(W SN)由于自身资源和计算能力的限制,导致其安全面临更严峻的挑战。因此,需要更加有效的安全防范机制。针对W SN自身资源和计算能力受制的安全特点和面临的欺骗、篡改或重发等八大主要攻击,提出了相应的安全防范措施,可以为传感器网络新技术的工作人员提供一定的借鉴。     

War Driving and WLAN Security Issues—Attacks, Security Design and Remedies

Mobile computing is evolving at a rapid pace with 802.11 networks; the fuzzy boundaries make it easy for intruders to intercept the radio signals. War driving was performed along highways; the resulting packet analysis is explained to show how easy some security attacks can be. An elaboration is done on a host of wireless security attacks that leads to the discussion of secure wireless network design, along with some network security simulation. The paper concludes with a list of security recommendations.     

无线传感网使用网络编码的新型数据传输方法

网络编码能提高无线传感器网络数据传输可靠性,针对现有基于网络编码的数据传输策略随机选取编码向量和使用固定路径所带来的缺陷,设计了一个新的编码矩阵构造方法,并提出了一种新型的基于网络编码的可靠数据传输方法。该编码方案能保证任意k个编码向量线性无关,且不用传输编码向量。数据转发使用"区域推进"机制,自动选取最佳转发节点,将数据包可靠地向sin"k推进",并实现了最少冗余传输和网络均衡能耗。分析与仿真表明,新的数据传输策略能消除现有方法的缺陷,提高数据传输可靠性,降低能耗。     

多源网络编码同态签名方案*

由于网络编码的系统很容易受到污染攻击,提出了一个适用于多源网络编码应对污染攻击的同态签名方案.该方案使用了同态哈希函数,能够阻止恶意修改的数据分组.被污染的数据分组会被验证者丢弃,从而保证了系统的安全性.该方案是同态的且是为多源网络编码特别设计的,与文件和分组的大小无关,而且方案中的公钥和每个分组的开销是常量.