Collaborative Non-Cryptographic Physical Layer Authentication Schemes in Wireless Networks

在無線網路的蓬勃發展下，無線網路安全之議題也漸漸受到重視，在探討安全的資訊傳輸之前，傳輸端的身份認證亦為無線網路安全之重要一環。除了傳統依靠網路上層的加密式認證技術，近年來諸多文獻亦多加探討藉由網路底層之特徵量進行傳輸端之身份認證，例如時鐘偏移量、無線通道響應、封包編號。本論文特別著重於兩種網路實體層之特徵：無線通道頻率響應及信號傳輸延遲時間，建立數學模型並以之發展出傳輸端身份認證演算法。此外，本文亦提出合作式身份認證演算法，目的在於當多個認證端存在時，能共同執行身份認證，降低認證錯誤的可能性。最後本文提出廣義多特徵合作式認證演算法，期使合作式認證不拘束於網路實體層特徵量，而能推廣至網路跨層合作式認證技術，盼能結合網路各層特徵量之優點，提供更為可靠的認證結果。模擬結果顯示，藉由實體層之特徵量作為身份認證確實可行，並可避免傳統加密式認證技術高計算複雜度之缺點。而合作式認證演算法更進一步提升認證效能，顯著地降低認證錯誤發生的可能性。Recently, many lower layer characteristics, such as clock skew, channel response, frame sequence number, are utilized to achieve the wireless security. Since the physical layer characteristics usually contain location-specific information, it can be used to complement or enhance the traditional security schemes. In this work, we focus on the problem of physical layer authentication (PHY authentication) which aims at assuring that the current transmission comes from the same entity as the previous transmission. In other words, the receiver analyzes the physical layer characteristics to discriminate from different transmitting devices. Two physical layer characteristics are considered separately, the frequency response of the wireless channel and the propagation delay. Collaborative authentication is also treated in this work. First, we consider collaborative authentication between different receivers observing the same physical layer characteristic; next we combine the authentication results from different characteristics to formulate the generalized multi-feature authentication. Although they are described under the discussion of physical layer characteristics, it is possible to apply the proposed scheme to formulate a collaborative cross-layer non-cryptographic authentication mechanism with moderate modifications. Simulation results show that the physical layer authentication is valid, and the proposed collaborative authentication schemes further improve the authentication performance