無線射頻辨識系統(RFID)是一種自動無線識別技術。由於射頻辨識系統的低成本與非接觸性的辨識特性，使得射頻辨識系統被廣泛的應用在各種領域上，如零售業、物流管理、製藥業、貨物控管等。然而，由於射頻辨識系統透過無線通訊，所以任何人均可竊聽通訊中的訊息。隨之而來的攻擊行為，如洩漏個人隱私，惡意追蹤，偽冒行為，都會危及使用者的安全與權益。
目前已經有許多相關的研究提出了各種方法來保護通訊的訊息，其中包含了使用認證協定來解決安全性的問題。但是這些研究中所提出方法都會有其缺點，有些會洩露使用者的位置隱私性，另一部份的協定雖然可以保護位置隱私性，但是卻會在辨識的過程中增加認證時的負擔，這樣的缺點，容易使系統遭受阻斷式攻擊，導致系統的癱瘓。
因此在本篇論文中，我們將探討無線射頻辨識系統的安全性問題，並討論一個安全的通訊協定應該要符合哪些安全性需求與特性，並分析為何目前這些被提出的協定無法滿足我們所提出安全性需求與特性。而在本研究中，吾人提出二種雙向認證協定。第一種協定能夠同時保護位置隱私性並減低系統在認證時的負擔。第二個協定不僅有第一個協定的特性，還徹底解決系統受到阻斷式攻擊的問題。

Radio Frequency Identification (RFID) is an automatic identification technology without the physical contact。Due to the low cost and conveniently identifying objects without physical contact,the RFID technology has been widely deployed in many applications that include
retail business,supply chain management, pharmaceutical industry, inventory control, etc. However, the wireless accessing characteristics of RFID system allows the outsider to easily eavesdrop the transmitted messages. The possible attacks including revealing user privacy, tracking problem and impersonation behavior produce the secure risk. Therefore, the design of an efficient and secure protocol without using complicate cryptographic
techniques for RFID systems is an important issue。
Though many authentication protocols for RFID have been proposed recently, they either cannot protect the location privacy of tags or have high overhead on identifying tags for the backed-end server。Moreover, an inefficient authentication protocol suffers easily the deny of service (DoS) attack. None of them provide satisfactory solution for both problems at the same time。
This paper proposes the security requirements and analyses the reason why these recently researches cannot fulfil the security requirements. This paper also proposes two mutual authentication protocols. The first protocol protects the location privacy and is efficiency on performing the authentication. The second protocol not only achieves the proposed requirements but also solve the attack of DoS completely.

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