Exploiting the inherent physical properties of wireless channels to complement or enhance the traditional security mechanisms has attracted prominent attention recently. However, the existing secret key generation schemes suffer from miscellaneous extracting procedure. Many PHY-layer authentication schemes assume that the knowledge of the shared key is preknown. In this paper, we propose PHY-layer secret key generation and authentication schemes for orthogonal frequency-division multiplexing (OFDM) systems. In the secret key generation scheme, to simplify the extracting procedure, only one legitimate party is chosen to probe the channel and quantize the measurements to obtain the preliminary key. The preliminary key is masked by the channel-phase after the mapping and before equalization and distributed to the other party. The final shared key is used for the PHY-layer authentication scheme in which random signals and the shared key masked by the channel-phase are exchanged at the PHY-layer. Then, a binary hypothesis test is formulated for authentication. Simulation results show that the proposed secret key generation scheme outperforms the existing schemes. For the PHY-layer authentication scheme, it is immune to various passive and active attacks and a high successful authentication rate is acquired even at low signal-to-noise ratio region.
Secret Key Generation Rate vs. Reconciliation Cost Using Wireless Channel Characteristics in Body Area Networks
