WEP通訊協定缺陷之研究

The study of the defects in WEP protocol

盧承忠(Chen-Chung Lu)

指導教授 ： 王振興 ； 王永鐘

國立臺北科技大學/機電學院/電機工程系所/碩士(2006年)

https://doi.org/10.6841/NTUT.2006.00250

摘要

由於無線區域網路建置的便利性與主機可移動性，使得採用無線區域網路連線的方式越來越盛行，目前無線區域網路連線主要是採用IEEE 802.11通訊協定，而此協定之封包加密大多是以WEP方式行之。又因為WEP設計的缺失，使得其所產生的密鑰喪失效用，亦即不需要知道這組密鑰也可透過簡單手法破解封包，取得使用者原始資料。
本論文主要是針對此設計瑕疵，提出ㄧ套破解WEP加密協定的方法。首先利用通訊協定特徵來猜測40位元組的金鑰序列。接著將此金鑰序列擴充至MTU長度。最後則是為每組初始向量建立對應之金鑰序列字典。經實作驗證本方法確實可行。

關鍵字

IEEE 802.11 ； 無線區域網路 ； 有線等效保密法 ； 安全性

並列摘要

Concerning the installation convenience and the mobility of hosts, the adoption of wireless local area network, which mainly chooses IEEE 802.11 for communication protocol and usually uses WEP for packet encryption, is getting more and more popular. But caused by the inherent WEP flaw, the generated secret key lost its effectiveness, i.e. the attacker can easily retrieve the plaintext without knowing the secret key.
In this paper, we proposed a method to crack WEP aimed at this flaw. First, we could imagine the first 40 bytes of the key sequence according to the characteristic of WEP. Then we extended this key sequence to the length of maximum transmission unit. Finally, the dictionary for all key sequences had been built up corresponding to every Initialization Vector. After implementation, we proved the effectiveness of this method.

並列關鍵字

IEEE 802.11 ； WLAN ； WEP ； Security

參考文獻

[2] J. Postel, " Internet Protocol," IETF RFC 791, Sep. 1981, www.ietf.org/rfc/rfc0791.txt

[3] R. Droms, "Dynamic Host Configuration Protocol," IETF RFC 2131, Mar. 1997, www.ietf.org/rfc/rfc2131.txt

[4] J. Postel, ed., "Internet Control Message Protocol," IETF RFC 792, Sept. 1981, www.ietf.org/rfc/rfc0792.txt

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[7] W. A. Arbaugh, "Wireless security is different," Published by the IEEE Computer, vol.36, no. 8, Aug. 2003, pp. 99-101.