在無線網路中，由於使用者共同享用相同的傳輸媒介，因此使得無線電頻率通訊極易受到感干擾攻擊。干擾者可以傳輸訊號來干擾合法的通訊，並且透過傳送大量的干擾訊號來暫時癱瘓網路。為了要解決這樣的問題，展頻技術─像是跳頻技術,直接序列展頻技術已經廣泛地被使用在抵禦干擾者的無線通訊上。而這兩種技術都是需要依賴傳輸節點在傳送資料之前，傳輸節點之間必須要有事先共享的秘密鑰匙(pre-shared secret key)才能成功地防禦干擾者。 在文獻中，有幾種解決方式是在有干擾者的狀況下，依據虛擬隨機跳頻(Pseudo-random Frequency Hopping)方法來建立鑰匙。然而，現有的虛擬隨機跳頻方法不是抵禦干擾者的能力較低，就是不論是在對稱式或是在非同步的環境底下皆無法保證節點相遇。本論文中，我們提出一個新穎的對稱式跳頻方法來抵禦干擾者，也保證在非同步的情況下節點之間能在一定的時間內相遇。 在我們的方法中，節點為了要能防禦攻擊者，在建立鑰匙階段會隨機跳頻。與現有的跳頻方法相比，我們的方法能有效地、強建地讓節點相遇並且建立鑰匙來抵抗干擾。 In wireless network, users share the transmission medium that makes Radio Frequency communication easy to suffer from jamming attacks. Jammer can transmit signals to interfere with legitimate communication and temporarily disable the network by mounting jamming attacks. To address this problem, Spread spectrum techniques (e.g., Frequency Hopping Spread Spectrum (FHSS), Direct Sequence Spread Spectrum (DSSS)) have been widely used for anti-jamming wireless communications. Both of them are reliance on the pre-shared secret key between the communicating node pairs prior to the communication. In the literature, several schemes relying on Pseudo-random Frequency Hopping (PFH) schemes have been studied to achieve resilient key establishment in presence of a jammer. However, existing PFH schemes either suffer from low resilience ability or are unable to guarantee rendezvous either in symmetric environments (every node has to play the role of sender and receiver intermittently) or time asynchronous environments. In this paper, we introduce a novel symmetric anti-jamming frequency hopping scheme that can guarantee rendezvous asynchronously within a bounded time. In our scheme, nodes hop over random frequencies during the key establishment phase, thus preventing jamming. Compared with existing frequency hopping schemes, our schemes can be an effective, robust rendezvous and key establishment scheme against jamming attack.
