Abstract: Wireless channel is of reciprocity, temporal variability and spatial variability. The legitimate users can generate secret key based on the property of the wireless channel. This paper proposes a calculation method for the capacity of the secret key. It establishes a reasonable wiretap channel model based on source of correlated randomness in the narrowband channel. The secret key capacity based on the phase of the received signal is deduced and the corresponding analytical expressions is obtained utilizing information theory and random signal processing theory on the basis of established channel model. The simulation results demonstrate that the secret key capacity is increased with the reciprocal extent of the channels between legitimate users and the SNR of received signals and the secret key capacity based on the phase information is smaller than the capacity based on received signals. Therefore, the legitimate users can apply the joint information distillation of envelope and phase in received signals to get more secret key bits.
flat fading channel,
secret key generation,
source of correlated randomness,
secret key capacity