近年來，車輛網路是個熱門的研究主題，在此環境下，每一車輛可以廣播訊息給其他車輛，通知他們改變行車路線來提高行車效率和避免車禍。因為車輛溝通是透過無線的傳輸通道，傳送訊息時可能會遭受到各種不同的惡意攻擊，因此，確保收到的訊息是沒有被竄改過和驗證訊息的來源性是重要的。此外我們還必須保護車輛的身分不被暴露以保護其隱私。為了滿足這些的安全特性，有許多相關的研究被提出，然而它們都有一些缺點存在，例如：1. 證書管理的成本和證書長期暴露的危險。2.需要RSU幫忙做認證：一旦需要幫忙的車輛越多，RSU的負擔就越重，而且也沒辦法達到及時的認證。
在本論文中，我們提出了一個匿名認證和金鑰協商機制，植基於變色龍雜湊函數和身分基礎技術。在我們的機制裡，每一車輛可以產生許多不同變色龍值去代表自己，而且其他車輛可以驗證這變色龍值是否為發出訊息的車輛所有，再者，有別於傳統的匿名認證方法，我們還利用身分基礎技術去做一對一的私密通訊，總之，我們的方法不僅克服了先前相關文獻的問題而且也滿足了在車輛網路所需的安全需求。

Vehicular ad-hoc network (VANETs) has been a hot research topic in recent years. In this environment, each vehicle can broadcast messages to other vehicles and inform drivers to change their route right away in order to enhance the efficiency of driving and to avoid accidents. Since vehicles communicate through wireless tunnel, many malicious attacks may occur during the transmission of messages. Consequently, ensuring the correctness of receiving messages and verifying the authenticity of the sender is necessary. Besides, we also need to protect the real identities of vehicles from revealing to guarantee the privacy. To satisfy these security properties, many related researches have been proposed. However, they all have some drawbacks. For example: 1. The cost of the certificate management and the exposure problem of the certificate. 2. Waiting for RSU to verify the messages: Once more vehicles need RSU, RSU will have much more overhead and it can’t achieve real-time authentication.
In this thesis, we come up with an anonymous authentication and key agreement scheme based on chameleon hashing and ID-based cryptography in the vehicular communication environment. In our scheme, every vehicle can generate many different chameleon hash values to represent itself, and others can prove the ownership of chameleon hash value. Furthermore, unlike other pseudonymous authentication schemes, we also achieve one-to-one private communication via ID-based cryptography. Finally, we not only overcome some problems in previous works but also fulfill some necessary security requirements in vehicular communication environment.

中文摘要 i
Abstract ii
Content iv
List of Figures v
List of Tables vi
Chapter1.Introduction 1
1.1. Vehicular Ad-Hoc Networks(VANETs) 1
1.2. Motivation 4
1.3. Design Objectives 5
1.4. Thesis Organization 8
Chapter2.Relate Works 9
Chapter3.System model 12
3.1. System Architecture 12
3.2. IBC Preliminaries 14
3.2.1. Shamir’s ID-based Cryptosystem 14
3.2.2. Bilinear Pairings and Hard Problems 15
3.2.3. Boneh and Franklin’s ID-Based Encryption 17
3.3. Chameleon Hashing 19
Chapter4.The Proposed Scheme 22
4.1. System Setup 23
4.2. Registration 25
4.3. Authentication and Key Agreement 29
4.3.1. Intra-RSU 29
4.3.2. Inter-RSU 31
4.4. Pseudonym and Key Updating 32
4.5. Communications in sparse RSU 34
Chapter5.Security and Performance Analysis 35
5.1. Security Analysis 35
5.2. Performance Analysis 38
Chapter6.Conclusion and Future Work 40
References 42

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