【作者】 刘辉；

【导师】 李晖；

【作者基本信息】 西安电子科技大学 ， 密码学， 2012， 博士

【摘要】 车载自组织网络(VehicularAd Hoc Networks, VANET，简称车载网)作为未来智能交通系统的基础，为车间通信创建了一个重要的平台，不仅能够提高交通效率，增加司乘人员的舒适性，而且还能够最大限度地减少或者避免道路安全事故的发生，它将为交通管理带来革命性的变化。但是由于无线网络本身的脆弱性和开放性，车载网也很容易受到攻击和破坏，面临着信息的伪造和篡改攻击、信息跟踪和重放攻击、女巫攻击和拒绝服务攻击等等，因此车载自组网的部署和实施必须满足信息的可认证性、完整性和不可否认性等安全需求，同时，还需要保护用户的隐私，要求车载网必须提供一种有条件的匿名信息认证协议。另外，由于车载网规模较大，涉及的通信实体数量较多，要求设计出健壮而且能够高效运行的车载网安全协议。车载网作为一种特殊的移动自组织网络，节点众多而且具有高速移动性，网络拓扑结构变化快，无线信道质量不稳定，节点移动受限制沿着车道进行具有一定的规律性，车辆发动机能够提供较充足的能源供应支持较大的储存能力和计算能力的设备等等，这些特性限制了一般的无线网络安全协议适用于车载网，因此必须为车载网设计专门的信息安全协议框架和方案，保障车载网的正常运行。本文针对车载网的实际状况，在车载网的信息认证机制和用户隐私保护方面进行了初步的研究和探索，提出了自己的一些想法，主要概括如下：(1)提出了车辆信息分类认证的思想，根据是否需要隐私保护把车载网的通信实体应分为两类，需要隐私保护的车辆比如个人车辆可以采用群签名认证机制，不需要隐私保护的车辆比如公用车辆和路边基础设施(RSU)可以采用基于身份的认证机制。(2)给出了车载网信息安全的一个协议框架，对通信实体分级分区进行管理，采用移动通信的群组管理模式，车辆可以进行漫游发送信息，每个区域有一个密钥管理中心负责为在本辖区内的车辆签发密钥，并管理区域内的RSU，每个区有一个交通执法中心，负责召回违规车辆的密钥，并实施处罚。(3)给出了一个信息认证和隐私保护的具体方案，方案使用了基于身份的签密技术和群签名技术，车辆通过签密和向密钥管理中心申请并定期更新签名密钥，然后可以在该区域内以群签名的方式签发信息，能够保护用户隐私。(4)给出了一个信息批量验证的算法，该算法能够用接近于常量值的时间来验证大批量的信息，使得信息验证的时间不随着信息量的增大而增加，能够减少车辆对信息的响应时间，并且有效地防范拒绝服务攻击。(5)针对伪造信息和虚假信息，提出了量化对比的方法，使得车载网能够以最小的代价使得欺骗攻击的难度加大。(6)给出了一个分布式的车载网密钥管理方案，车辆通过无证书签密的方式向密钥中心申请笔名，利用笔名进行签发信息可以有效地隐藏用户身份，接收者可以对收到的大量信息进行批量验证，该方案适合大规模车载网的安全需求。更多还原

【Abstract】 As the infrastructure of future intelligent transportation system, Vehicular ad hocnetworks (VANET) enables communication between vehicles, which can not onlyimprove traffic efficiency and increase the drivers’ experience and comfort, but alsodecrease or avoid the traffic accidents as soon as possible, so VANET can play arevolutionary role in traffic regulation. However due to vulnerability and openness ofthe wireless network, it is very easy for VANET to be attack, for example, bogusinformation attack, message replay attack, sybil attack, denial of service (DOS) attackand so on. To countermeasure and mitigate the potential threats, a well-developedsecurity protocol for VANET should meet the following requirements: data originauthentication and integrity, revocability, anonymity, non-reputation and so on.Meanwhile, VANET should preserve the users’ privacy, so the protocol is a conditionalauthentication scheme. Also, VANET consists of a huge number of vehicles, whichrequires one efficient security protocol.VANET is one special kind of mobile ad hoc networks, its node’ number is large andevery node moves very fast, so the net topology changes quickly, furthermore, thewireless channel is not stable, but the nodes moves along the road and the vehicles’engine can provide enough power for communication units. These characteristics bringa lot of challenges in the aspects of security and privacy. So one special kind of securityprotocol should be designed for VANET message authentication.According to the actual state of VANET, some preliminary research and explorationis developed on message authentication and privacy preservation, some new securityprotocols are proposed as follows:(1) Vehicle-based classification authentication protocol is proposed for the messagein VANET, vehicles are classified into categories according to privacy preservation,some vehicles need privacy, for example the private cars, so the messages from them areverified by group signature, the others needn’t privacy preservation, for example theRSUs and the public vehicles, so the messages from them should be verified byidentity-based signature.(2) Information security framework is proposed for VANET, all nodes and entitiesare managed by hierarchies and levels, group-based regulation mode is exploited, thevehicles can roam to send and receive messages, every domain has one CA whichresponsible for signing private keys for the vehicles in the local and regulating the localRSUs, every domain has one TA (Tracing Authority) responsible for revoking the illegal vehicles and punishing them.(3)An efficient privacy-preserving authentication scheme is proposed,in whichgroup signature and ID-based signcryption are exploited, the vehicles can apply andrenew their private key from the CA by signcryption, and then they can signing andsending messages on behalf of the group, which can preserve the users’ privacy.(4)Batch verification algorithms are proposed, these algorithms can verify a largenumber of messages in the approximately fixed period of time, and the verification timecan not increase along with the increase of messages, which can reduce response timeon the safety messages and resist the DOS attack.(5)Quantitative comparison and determination is employed to handle the conflictinginformation, which can increase the difficulty of invasion in minimum cost.(6)A distributed key management protocol for VANET, in which vehicles can obtainone pseudonym by certificateless signcryption, then the vehicles can use the pseudonymto hide themselves, so they can securely sign and send messages, the receivers canverify a large number of the messages by batch verification, the protocol can meet therequirements of the large-scale VANET.更多还原