High-rate secret key generation aided by multiple relays for Internet of things

A multiple relays aided secret key generation algorithm is proposed to improve the generated secret key rate for Internet of things when the wireless channels change slowly. First, the two legitimate users and relays send training sequences in turn to estimate the channels. Then, the relays employ secure network coding technique to help the two legitimate users exploit the randomness of relay channels. Finally, the two legitimate users agree on a secret key without the help of relays. In addition, the optimal relays selection with optimal power allocation algorithm is present to further improve the secret key rate when relay selection is needed. The performances of the proposed algorithms are verified by Monte Carlo simulation results.