Experimental characterization of channel-based key establishment using reconfigurable antennas

Generation of secret encryption keys from the reciprocal electromagnetic channel represents an emerging topic within the broad field of propagation channel research. This paper uses multi-antenna channel measurements to assess the potential performance of such techniques, with the emphasis on using a reconfigurable antenna element controlled by the channel sounder to create time-variation in the wireless channel that enables establishment of long encryption keys. The results demonstrate that reconfigurable antennas can significantly enhance the security, even when the eavesdropper antennas are adjacent to or surround one of the legitimate nodes.