Secret key generation based on two-way randomness for TDD-SISO system

A novel secret key generation (SKG) method based on two-way randomness is proposed for TDD-SISO system. The legitimate transceivers mutually transmit their own random signal via reciprocal wireless channel, then the multiplication of transmitted and received signal is used as common randomness to generate secret keys. In quasi-static channel, the theoretical SKG rates (SKGRs) of the three SKG methods, namely wireless channel based, one-way randomness and two-way randomness, are derived and compared. Further, two practical SKG schemes based on two-way randomness, Scheme-1bit and Scheme-3bit, are completely designed and simulated. Generally, Scheme-1bit applies to low signal to noise ratio (SNR) scenarios and achieves 0.13∼0.86bit/Ts SKGR and 10−2∼10−5 level secret key outage probability (SKOP), while Scheme-3bit fits high SNR situation and obtains 0.93∼1.35bit/Ts SKGR and 10−3∼10−4 level SKOP. At last, the national institute of standards and technology (NIST) test is conducted to evaluate the secret key randomness (SKRD) and the test results show that both of the proposed schemes have passed the test.