Efficient Key Generation by Exploiting Randomness From Channel Responses of Individual OFDM Subcarriers

Experimental study on channel reciprocity in wireless key generation

“…This arrangement enables us to investigate the effect of noise without the impact of non-simultaneous sampling and to quantify their contribution to the signal cross-correlation. Results have revealed that when the sampling time difference is small (e.g., 0.06 ms), noise is the main factor that influences the cross-correlation relationship of the measurements in a slow fading channel (e.g., with coherence time as about 50 ms), which matches our theoretical analysis in [15]. We also found the resolution of the sampling time difference can be satisfied by wireless systems such as IEEE 802.11 to maintain an acceptable crosscorrelation coefficient without affecting the bandwidth and communication efficiency.…”

“…We have theoretically modelled and analyzed the effects of non-simultaneous measurements and noise on the crosscorrelation of the measurements in [15], and found that noise has a more dominant impact in a slow fading channel. In this paper, we carried out an experimental study.…”

Secure Wireless Key Establishment Using Retrodirective Array

“…In this case the eavesdropping channel vector at frequency f 2 , denoted as P 2 , seen in Fig. 2, is correlated to H 2 through the correlation coefficient ρ RD A ae expressed in (12). Here only real part, i.e., Re(·), is considered.…”

“…There are several characteristics of wireless channels that can be utilized to extract secret keys, such as received signal strength (RSS) [9], channel phase delays [10], multipath relative time delays [11], and full channel state information (CSI) [12]. These parameters are available in network interface cards or customized hardware platforms, therefore many practical key generation systems have been reported [7].…”

“…In [9], [13] multiple nodes or multiple antennas at each node are exploited in order to create multiple usable common channels from which more key bits can be extracted within one channel coherence time period. Similarly, multiple independent or quasi-independent channels can be generated using frequency resources, such as channel hopping in [14], and OFDM signals in [12]. A concept ultilizing random beamforming was proposed in [14], [15].…”