Our research projects include:

• Exploting multiple-antenna diversity for secret shared key generation from wireless channel
  Generating a secret key between two parties by extracting the shared randomness in the wireless fading channel is an emerging area of research. We proposed and implemented a shared secret key generation protocol using off-the-shelf 802.11n multiple-antenna devices. By taking advantage of the multiple-antenna diversity, our protocol increased the bit generation rate by more than four times over existing single-antenna systems. This is the first work on generating the shared secret key from the wireless channel using off-the-shelf 802.11n devices, and it has led to a paper accepted in IEEE Infocom 2010.
• Jamming-resistant communicaiton without negotiation
  Channel surfing is an effective method to prevent jamming attacks in wireless communications. In traditional channel surfing schemes, two parties have to negotiate beforehand, in order to agree on the channel switching sequence. However, the negotiation process itself is vulnerable to jamming attacks. Aiming at solving this dilemma, we proposed a novel channel surfing method without relying on such negotiation. Taking advantage of the reciprocity of the wireless fading channel, our method switches channels according to the random channel states observed by the two parties during their communication. Therefore, it does not introduce any extra communication overhead and can achieve perfect security. Experimental results validate the efficiency and security of our method. A paper on this work will appear in IEEE ICC 2010.
• Received signal strength based authentication in mobile wireless networks
  Channel state or signalprints based authentication schemes have attracted a lot of attention in recent years. However, existing schemes can only apply in static networks, where the channel states or signalprints are relatively stable. In a mobile environment, the channel state and signalprints are changing over time, which invalidates the usability of the existing schemes. With this motivation, we proposed a novel authentication scheme by exploiting the channel auto-correlation and reciprocity in mobile environments. Experimental work validates that our scheme can achieve high detection rate with low false alarm rate in mobile networks. Multiple antenna diversity can significantly improve the performance of our scheme. This study has led to a submission to ACM MobiSys 2010.
• Location proximity based authentication in wireless networks
  We proposed a scheme for authenticating nearby wireless devices that share no prior secrets by taking advantage of their closeness and multiple-antenna diversity. When a nearby sender is very close to one antenna on the receiver, the receiver can observe a large difference between the power measured on its two antennas, whereas a faraway sender would be unable to induce this large difference. We validated our scheme through theoretical analysis and experimental measurements. This work has resulted in a paper submitted to USENIX Security 2010.