@inproceedings{liu_ning_dai_liu_2010, title={Randomized differential DSSS: Jamming-resistant wireless broadcast communication}, DOI={10.1109/infcom.2010.5462156}, abstractNote={Jamming resistance is crucial for applications where reliable wireless communication is required. Spread spectrum techniques such as Frequency Hopping Spread Spectrum (FHSS) and Direct Sequence Spread Spectrum (DSSS) have been used as countermeasures against jamming attacks. Traditional anti-jamming techniques require that senders and receivers share a secret key in order to communicate with each other. However, such a requirement prevents these techniques from being effective for anti-jamming broadcast communication, where a jammer may learn the shared key from a compromised or malicious receiver and disrupt the reception at normal receivers. In this paper, we propose a Randomized Differential DSSS (RD-DSSS) scheme to achieve anti-jamming broadcast communication without shared keys. RD-DSSS encodes each bit of data using the correlation of unpredictable spreading codes. Specifically, bit ``0'' is encoded using two different spreading codes, which have low correlation with each other, while bit ``1'' is encoded using two identical spreading codes, which have high correlation. To defeat reactive jamming attacks, RD-DSSS uses multiple spreading code sequences to spread each message and rearranges the spread output before transmitting it. Our theoretical analysis and simulation results show that RD-DSSS can effectively defeat jamming attacks for anti-jamming broadcast communication without shared keys.}, booktitle={2010 proceedings ieee infocom}, author={Liu, Y. and Ning, P. and Dai, H. Y. and Liu, A.}, year={2010} }
 @article{liu_ning_liu_wang_du_2008, title={Attack-resistant location estimation in wireless sensor networks}, volume={11}, ISSN={["1557-7406"]}, DOI={10.1145/1380564.1380570}, abstractNote={
            Many sensor network applications require sensors' locations to function correctly. Despite the recent advances, location discovery for sensor networks in
            hostile environments
            has been mostly overlooked. Most of the existing localization protocols for sensor networks are vulnerable in hostile environments. The security of location discovery can certainly be enhanced by authentication. However, the possible node compromises and the fact that location determination uses certain physical features (e.g., received signal strength) of radio signals make authentication not as effective as in traditional security applications. This article presents two methods to tolerate malicious attacks against range-based location discovery in sensor networks. The first method filters out malicious beacon signals on the basis of the “consistency” among multiple beacon signals, while the second method tolerates malicious beacon signals by adopting an iteratively refined voting scheme. Both methods can survive malicious attacks even if the attacks bypass authentication, provided that the benign beacon signals constitute the majority of the beacon signals. This article also presents the implementation and experimental evaluation (through both field experiments and simulation) of all the secure and resilient location estimation schemes that can be used on the current generation of sensor platforms (e.g., MICA series of motes), including the techniques proposed in this article, in a network of MICAz motes. The experimental results demonstrate the effectiveness of the proposed methods, and also give the secure and resilient location estimation scheme most suitable for the current generation of sensor networks.
          }, number={4}, journal={ACM TRANSACTIONS ON INFORMATION AND SYSTEM SECURITY}, author={Liu, Donggang and Ning, Peng and Liu, An and Wang, Cliff and Du, Wenliang Kevin}, year={2008}, month={Jul} }