| 摘要: | 隨著無線網路技術的進步，許多通訊相關的應用隨之發展，其中一項典型且有別於傳統的應用為智慧型運輸系統，其整合資訊與通訊技術，進而強化道路安全與提高交通運輸效率。而各式各樣相關的研究與應用也儼然而生，包含維護車間安全、車流管理、駕駛輔助應用、多媒體加值應用等網路服務。此外，考慮資料在車間網路傳遞的正確性及匿名性，訊息的傳輸需經過合法憑證的認證，以杜絕不法車輛的惡意攻擊；然而，現有的憑證管理系統存在漏洞，使得執法機關可用以追蹤車輛，造成使用者喪失隱私。
本論文首先探討車流管理，致力於設計改善道路運輸流量的機制，以減少道路擁塞並保證道路安全。我們提出集中式的車流管理方法，透過車輛回報位置的機制，推送適合的路徑；在計算路徑上，考慮車輛在不同道路延遲下的行車時間，並且納入繞路機制，透過模擬分析，我們的方法有效降低傳統車輛的路由的時間。
雖然智慧運輸系統帶來車輛安全與效能的提升，但車間通訊伴隨隱私的洩漏。由於傳送方與接收方彼此能夠識別對方，若通訊的驗證機制無法保持匿名，攻擊者即可透過身分識別資料來進行車輛追蹤，侵犯使用者隱私。更甚，車間通訊必須避免攻擊者散播不實的資訊，除了要能設計可靠的感測器進行偵測之外，也必須將不法的車輛從車輛網路移除，以正視聽。權責性的問責將交由憑證管理系統來進行驗證，撤銷不法車輛相當於要能夠辨別不法車輛，權責與隱私之間必須取得微妙的平衡。目前，美國交通運輸部考慮在 2020 年推動車間網路，並且提出 SCMS 憑證管理系統，但很遺憾的，目前系統存在不當設計造成使用者隱私可能被侵犯，本文將探討系統設計並提出改善機制以維護車輛隱私。
;Recent advances in the wireless network technologies have triggered the deployment of communications in many applications. Among them, the intelligent transportation system (ITS) is a typical example that may change the traditional life. ITS integrates information and telecommunication technology to enhance road safety and transportation efficiency. A wide range of applications has emerged, including public safety applications, traffic management applications, driver support applications, infotainment applications in network services. Besides, to achieve data correctness and anonymity from misbehaving and malicious vehicles, message must to be signed by the certificate before its transmission. However, the current Security Credential Management System (SCMS) is vulnerable and enables law enforcement to track the vehicle and compromise users’ privacy.
In this dissertation, we first explore the traffic management applications and aim at improving traffic throughput of the transportation system to reduce traffic congestion and preserve road safety. We propose a centralized dispatching approach to compute routing paths for each vehicle based on its source and destination. Furthermore, the mechanism considers not only the routing costs but also safety factors and introduces detour method as alternative path selection. We evaluate the performance through the simulation analysis, and the result shows that our approach significantly outperforms traditional approach for transportation time.
Though ITS enables to provide smarter and safer transportation applications, data breach is introduced by vehicular communications. If the transmitter and the sender cannot preform anonymous communication, the attacker is able to track the vehicles and compromise vehicles’ privacy. In addition, the system must to be capable to prevent attackers from disseminating false messages. Not only the reliable and sophisticated sensor is required, but also the system needs to remove out the misbehaving vehicles to enhance system robustness. For accountability reasons, the credential management system is responsible for misbehavior detection and certificate revocation. In other words, the system can identify the misbehaving vehicle. Thus, the design of the system requires a delicate balance between privacy and accountability. Currently, National Highway Traffic Safety Administration (NHTSA) has announced its plan to deploy VANETs by 2020 and the SCMS is the leading credential management system in the US. Unfortunately, the current SCMS design fails to achieve its design goal and compromise users’ privacy. In this dissertation, we propose a solution to enhance the system security and preserve users’ privacy. |
