RSS-based secret key generation for indoor and outdoor WBANs using on-body sensor nodes

Given that the market of wearables is in so-called hypergrowth mode, more and more of these on-body devices will interact with each other. These body-to-body, device-to-device links should not only provide reliable but also secure communication of personal user data. Therefore, we have analyzed the potential of using the unique reciprocal body-to-body channel between two legitimate parties, to create a high-level security key that is unknown to an eavesdropper. Both randomly moving legitimate parties, typically called Alice and Bob, were equipped with low-power wireless on-body sensor nodes, which collect the Received Signal Strength values. Additionally, the eavesdropper Eve, who is continuously sniffing the body-to-body channel using a third sensor node, collects her own sequence of RSS values, which are expected to be highly decorrelated from the RSS values from both Alice and Bob. Based on a statistical analysis, applied to Received Signal Strength values to verify the correlation, entropy and mutual information, the body-to-body link seems very suitable for RSS-based secret key generation in indoor and outdoor Wireless Body Area Networks. Moreover, this practical and lightweight alternative for secret key generation ensures low on-chip complexity and, hence, low computational power consumption.