Secret key generation based on channel and distance measurements

Within the paradigm of physical layer secrecy, typically a physical layer specific characteristic is used as key generator to guarantee information hiding from eavesdroppers. In this paper, we propose a novel secret key generation algorithm based on two reciprocal physical layer parameters; the channel measurements and the distances between the two communicating nodes. The two parameters are estimated experimentally using implementations of our algorithm on three FPGA-based WARP kits emulating the two communicating nodes and the eavesdropper. The parameters are used as common sources of randomness to generate the secret key. We evaluate the performance of our algorithm through extensive iterations. We compare the bit mismatch rate as well as the entropy of the generated secret key of our algorithm versus classical channel only and distance only based algorithms. Our results reveal that even in the worst case scenarios, our algorithm outperforms the two other algorithms and overcomes their vulnerabilities.