Retrodirective-Assisted Secure Wireless Key Establishment

In this paper, a new type of architecture for secure wireless key establishment is proposed. A retrodirective array (RDA) that is configured to receive and re-transmit at different frequencies is utilized as a relay node. The RDA is able to respond in "real time," reducing the required number of time slots to two. More importantly, in this architecture, equivalent reciprocal wireless channels between legitimate keying nodes can be randomly updated within one channel coherence time period, leading to greatly increased key generation rates in slow fading environment. The secrecy performance of this RDA-assisted key generation system is evaluated under several eavesdropping strategies and it is shown that it outperforms previous relay key generation systems.