Secret key generation through OFDM multipath channel

We analyze the fundamental limits of key generation and describe an implementation based on error correcting codes. We show that key extraction based on channel coefficients significantly outperforms key extraction based on received signal strength indicators (RSSI). The development in this paper is based on an IEEE 802.11a orthogonal frequency-division multiplexing (OFDM) model and We demonstrate that it is feasible to use the sampled channel coefficients in OFDM as the key source. The key extraction problem is cast as a Slepian-Wolf coding and decoding problem. We construct regular and irregular forms of binary and non-binary low-density parity check (LDPC) codes to prototype our key extraction.