Secret Key Generation Via Localization and Mobility

We consider secret key generation by a pair of mobile nodes utilizing observations of their relative locations in the presence of a mobile eavesdropper. In our proposed algorithm, the legitimate node pair makes noisy observations of the relative locations of each other. Based on these observations, the nodes generate secret key bits via information reconciliation, data compression, and privacy amplification. We characterize a theoretically achievable secret key bit rate in terms of the observation noise variance at the legitimate nodes and the eavesdropper and show that the performance of our algorithm is comparable to the theoretical bounds. We also test our algorithm in a vehicular setting based on observations made using wireless beacon exchange between the legitimate nodes. To achieve this, we used TelosB wireless radios mounted on the sides of the vehicles on local roads and freeways. Note that our approach relies solely on distance reciprocity, and thus, it is not restricted to the use of wireless radios and can be used with other localization systems (e.g., infrared and ultrasound systems) as well. Overall, this study proves, via both information theoretic and practical analysis, that localization information provides a significant additional resource for secret key generation in mobile networks.