Verification of Wireless Key Generation Using Software Defined Radio

Use of random channel variations in wireless communication systems is a promising way for establishing secret shared encryption keys in a given pair of nodes. The paper considers an implementation of secret key generation using randomness of carrier phase in a multipath environment on the basis of Software Defined Radio system (SDR). The use of SDR-technology ensured flexible tuning of radio frequency parameters. The methods for generating, transmitting and receiving of probe signals that allow fast changing of system parameters during experiments are described. An implementation of control software for key generation using the free and open-source development toolkit GNU Radio is presented. We also present the results of experimental verification of key generation in typical indoor environment using the values of carrier phase measured in three different frequency bands of 433 MHz, 900 MHz, and 2400 MHz, respectively. A comparative analysis of achieved key generation rates in each of the frequency bands is provided. Based on the results, we identify principal physical factors that limit the system performance in different frequency bands.