On the Negatively Correlated Eavesdropper in Indoor Wireless Body Area Networks

Wireless Physical Layer Security (WPLS) provides attractive lightweight data security methods suitable for resource constrained Wireless Body Area Networks (WBANs). As WPLS methods entirely rely on wireless transmission, they are prone to eavesdropping. Most previous work assume that the eavesdropper's channel is independent if it is more than half a wavelength away from the legitimate participants. In this paper, we demonstrate that due to unique properties of WBANs, this assumption does not hold. In particular, the body shadowing phenomenon gives rise to negative correlation that can be easily exploited by the eavesdropper without being anywhere near the legitimate parties.