| In recent decades, wireless communication technology has been widely deployed and increasingly adopted. As wireless devices become ubiquitous, more and more attacks targeting wireless device emerge, including the wireless jamming attack and the man-in-the-middle attack to the wireless pairing process. On the other hand, the recent advances in the software-defined radio give us the flexibility to design and control wireless physical layer signals. We found that the wireless physical layer signal has some properties, which can be used to preserve wireless security.;In this dissertation, we first proposed a novel technique - Multi-Channel Ratio (MCR) Decoding, which aims at providing the anti-jamming wireless communication capability for multi-antenna wireless devices. The basic idea of MCR decoding is to fully leverage the repeated preamble signals and the multi-channel characteristics in MIMO communications to detect and recover desired transmission signals under constant and reactive jamming attacks. It is shown that the proposed MCR decoding can detect the desired transmission reliably under the jamming attack and remove jamming signals effectively.;After that, we explored the feasibility of using jamming to achieve wireless access control. We proposed a novel mechanism, called Ally Friendly Jamming, which provides an intelligent jamming capability that can disable unauthorized wireless communication but at the same time still allow authorized wireless devices to communicate, even if all these devices operate at the same frequency. The basic idea is to jam the wireless channel continuously but properly control the jamming signals with secret keys, so that the jamming signals are unpredictable interference to unauthorized devices, but are removable at authorized ones equipped with the secret keys. To achieve ally friendly jamming, we developed new techniques to generate ally jamming signals, to remove jamming signals from multiple ally jammers. Both the analytical and experimental results indicated that the proposed techniques can effectively disable enemy wireless communication and at the same time maintain wireless communication between authorized devices.;We further proposed Fast Friendly Jamming, which eliminates the need for demodulation and enables the friendly jammer to verify the received signals directly on the physical layer. We have implemented a prototype of the proposed techniques based on GNURadio and USRP, and performed real-world experiments to validate the proposed techniques. The experimental results showed that the proposed techniques reduce the reaction delay of the friendly jammer by 81:9% -- 85:7%, and achieve accurate distinction between allies' and enemies' transmissions.;Wireless jamming attack is also used to launch the man-in-the-middle attack to wireless pairing. To address this problem, we presented a novel wireless in-band pairing design, in which the pairing device utilizes the 802.11 Clear to Send (CTS) reserved duration to detect the existence of possible attackers in the network. We further proposed to use the on/off sub-carriers in the frequency domain to convey the hash digest bits to protect the integrity of the benign pairing messages. Compared with the previous work, our design reduces most of the channel occupation time by eliminating the long synchronization packet and the on/off slots in the time domain. Our evaluation results showed that the proposed technique of using sub-carriers to convey hash bits works accurately in the real-world environment. |
