Wireless security enhancement using parasitic reconfigurable aperture antennas

The ability of parasitic reconfigurable aperture (RECAP) antennas to generate secret keys is investigated, which allows physical-layer reciprocal channel key generation (RCKG) methods to be employed even in the case of static and line-of-sight channels. Since the artificial channel fluctuations created by RECAP structures are not necessarily Gaussian, a numerical procedure for computing available and secure key bits is developed that is applicable to channels with arbitrary fading. It is identified that for limited RECAP complexity, a reduced-complexity brute-force attack is possible, and a lower bound on the required RECAP complexity to avoid this possibility is developed. Numerical examples of a 9×9 parasitic RECAP with varying levels of complexity illustrate the importance of controlling the reflection coefficient to ensure Gaussian statistics, the need for sufficient complexity to attain maximum secure key bits, and the importance of placing the RECAP on the node near the eavesdropper.