無線網路實體層之整合性安全設計

資訊安全是無線通訊領域中的一個重要議題。然而在無線通訊日益普遍的今日，機密的通訊卻仍然是由傳統的加密技術來保護。近來逐漸有許多嘗試利用無線傳媒特性的實體層加密技術問世，但無線傳媒仍然是塊尚未獲得充分發揮的處女地。在本論文中，我們提出了一個運用底層網路技術的整合性安全設計。我們先將一個把網路編碼技術發揮到實體層的概念發展成熟，稱之為實體層網路編碼技術。再將我們開發出來的實體層網路編碼技術結合隨機接收波束成形演算法以及另外兩個安全機制，確保了傳輸維持在低攔截機率。我們的方法與現存的實體層加密技術最主要的不同在於，我們的方法幾乎可以適應任何的無線環境。而且使用者無需保持移動狀態才能確保通訊安全。為了顯示我們的整合性安全設計易實現於尋常的通訊系統，我們選擇一個尋常的正交分頻多工位元交錯調變碼系統架構作為我們系統的基礎架構。並且進一步以 IEEE 802.11n 標準和 TGn 通道模型作為我們的系統模擬設定，測試系統在現實環境中的安全性。於是我們系統的低攔截機率目標以蒙地卡羅法得到驗證。最後，由於有效的竊聽攻擊方法尚未被找到，我們提出一種暴力攻擊法來攻擊我們的安全系統，並證明其複雜度高到無法威脅系統的安全。

關鍵字

機密性；低攔截機率；實體層；正交分頻多工；實體層網路編碼；反向聽測協定；波束成形

並列摘要

Keeping information confidential is one of the important issues in wireless communications. Although it is getting widespread in our daily lives, the confidentiality is still protected by conventional encryption techniques. Recently, there have been many works about physical-layer (PHY) security techniques intending to exploit the unique characteristic of the wireless medium. However, the wireless medium is still the rich source that has not been well exploited. An integrated security design via lower layer techniques is proposed in this thesis. We develop a physical-layer network coding technique that well suits for confidential communications. By incorporating the special physical-layer network coding technique with a random receive beamforming algorithm and another two security mechanisms, the wireless transmissions with low probability-of-interception (LPI) can be guaranteed. One of the major differences between our approach and existing physical-layer security approaches is that our security design has nearly no limit of wireless environment. The users do not need to keep mobile. A typical BICM-OFDM structure is selected to be our basic system, and to show how to easily apply our security design techniques into usual communication systems. To verify the practicability of our security system, we use the IEEE 802.11n standard as the base of our physical-layer specification and the TGn channel models as our channel model. With these realistic settings, the LPI of our security system is verified by Monte Carlo methods. Since the effective attack by eavesdroppers has not been found, we provides a brute-force attack and proves that it has a considerable complexity.

並列關鍵字

Confidentiality ； LPI ； Physical-layer,OFDM ； Physical-layer Network Coding ； Sounding Protocol ； Beamforming

參考文獻

[2] W. Trappe and L. C. Washington, Introduction to Cryptography with Coding Theroy. Prentice Hall, July 2005.

[3] C. E. Shannon, "Communication theory of secrecy systems," Bell System Technical Journal, Tech. Rep., 1949.

[4] A. D. Wyner, "The wire-tap channel," Bell System Technical Journal, Tech. Rep. 8, Oct. 1975.

[6] S. K. Leung-Yan-Cheong and M. E. Hellman, "The gaussian wire-tap channel," IEEE Transactions on Information Theory, vol. 24, pp. 451-456, July 1978.

[8] Y. Liang, H. V. Poor, and S. Shamai, "Secure communication over fading channels," IEEE Transations on Information Theory, vol. 54, pp. 2470-2492, June 2008.

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無線網路實體層之整合性安全設計

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