在行動無線射頻辨識系統上的認證機制

Authentication Schemes for Mobile Radio Frequency Identification Systems

呂臣恩(Chen-En Lu)

指導教授 ： 孫宏民

國立清華大學/電機資訊學院/資訊系統與應用研究所/碩士(2007年)

https://doi.org/10.6843/NTHU.2007.00301

摘要

無線射頻辨識技術已經被廣泛地應用在許多環境中，如零售業供應鏈、付費系統、門禁系統等。為了避免使用者隱私受到侵犯，在無線射頻辨識系統上的防護措施有其必要性。過去文獻已提出許多機制以解決隱私問題，然而，這些機制仍然有無法抵擋的攻擊並有一些缺點。即使在標籤上做硬體防護可以阻止被未經許可的讀取，但現實中的應用卻會受到限制。目前，已有許多措施用密碼認證以保護隱私。由於標籤的運算能力和資源有限，強大的加解密演算法不適合實作在低成本的被動式標籤上，但比較簡易的密碼學方式是可行的。
在過去的無線射頻辨識系統中，後端伺服器和讀取器被視為同一方角色，它們之間的通訊管道被假定為安全而不遭受竊聽的。許多機制只提供在標籤和讀取器之間的認證。在行動環境中，任何人可以持有一個內嵌主動式無線射頻辨識發送及接收器的行動裝置，讀取物品上附著的標籤且得到回應訊息後，透過無線通道傳送資料給後端伺服器並獲取資訊及服務。雖然這樣的架構很方便，可是通訊管道變得不再安全。此外若資料庫內所有標籤的相關資訊，不是所有讀取器有授權可以存取時，將構成資料隱私權的一項威脅。
在這篇論文中，我們提出的兩套認證機制皆有提供存取授權的管理以及解決在無線環境下的可能威脅。第ㄧ套機制可以抵擋數個在無線射頻辨識系統上會遭遇的攻擊，並且提供一個有效率的標籤辨識的方法，避免伺服器在資料庫中搜尋時耗費大量運算而導致效率低落。透過一把共享的秘密金鑰，伺服器得以判斷某一個讀取器有哪些標籤的讀取權限，進而達到每一個標籤的存取權限管理。另外一套機制則強化了過去交易的隱私保護，以及針對讀取器持有人的位置隱私，確保讀取器發送的請求訊息可以防止敵人追蹤。根據應用環境的需求，我們可以在效率和安全兩個考量上選擇最適合的機制。

關鍵字

認證 ； 行動 ； 隱私 ； 協定 ； 無線射頻辨識 ； 讀取器權限管理

並列摘要

There have been various mechanisms proposed to address privacy problems, however, they are still vulnerable to different attacks and leaves a few weaknesses. Although existing hardware-based approaches prevent unauthorized reading, those are restricted in practice. At present, many solutions introducing cryptographic authentication have been suggested to protect user privacy. Because of constraint resources, strong cryptography is not suitable for passive and low-cost RFID tags, but weaker cryptographic primitives are widely adopted among authentication protocols.
In the past works, a reader and the back-end server are considered as a single entity, and the internal communication channel is secure. Many schemes only provide authentication between a server and a tag. In the mobile RFID environment, anyone who possesses a mobile device equipped with active RFID transmitter/receiver can interact with RFID-tagged objects, and acquire information from a back-end server through wireless communications. For this reason, it ought to achieve proper reader authentication.
In this thesis, we propose two authentication schemes to resolve privacy threats in a mobile environment, where a mobile reader is not authorized to acquire every tag’s related data. One achieves many security requirements with efficient tag identification, which helps the server save an exhaustive search in its database. This scheme determines whether if a reader has the proper access right or not through a shared secret key. The other is able to enhance forward privacy of transactions, and keep a reader anonymous when a reader user’s location privacy is considered. These two authentication schemes are trade-off and based on two chief considerations: efficiency and security. The trade-offs are chosen relying on what application environment the RFID system is applied in.

並列關鍵字

Authentication ； Mobile ； Privacy ； Protocol ； RFID ； Reader Right Management