Security of a position-based secret key generation method

With the increasing demand for security, many systems take advantage of channel randomness to generate secret keys. However, when an eavesdropper has good knowledge of the environmental information and the position information of legal users, this method is not absolutely safe. The scattering environmental information cannot be kept secret but the system can still be secure based on the uncertainty of the positions of legal users due to the users movements and the limited observation ability of the eavesdroppers. This study analyzes the security of the position-based secret keys generation method with the security measured by the secret key rates. The calculational errors of the positions of the legal users in different scenarios (LOS, NLOS and different numbers of scattering objects) are analyzed first. Then, the impacts of the distance observation error, the azimuth observation error and the number of observations in each secret key generation period on the secret key rates are analyzed in simulations. The results show that the uncertainty of the positions of legal users can be used to provide security for the secret keys.