Experimental study of performance and security constraints on wireless key distribution using random phase of multipath radio signal

The paper presents the results of experimental distribution of encryption keys based on random carrier phase of fading radio signal measured in a multipath environment. The random bits extraction scheme was proposed and tested in practice. The proposed scheme is universal and applicable to measurements digitizing of any observable random variable. Experimental study of spatial correlation of multipath signal phase in the case of transverse spatial diversity is carried out. Experimental estimation of the key generation rate and the probability of its passive interception at different distances between the legal user and potential eavesdropper are also performed. It is shown that the parameters of bit extraction procedure significantly affect on the performance and security of the key distribution process.