High-Rate Secret Key Generation Method Using Two-Way Random Signal

Most secret key generation (SKG) methods need channel estimation and provide insufficient performance especially in time division duplex single input single output (TDD-SISO) system and quasi-static channel scenario. This paper proposed a two-way SKG method which can completely avoid channel estimation and achieve higher SKG rate (SKGR). Firstly, the legitimate users mutually send their own random signal via the reciprocal channel. Then, the multiplication of local random signal and the received signal can be used as common randomness to generate keys. The theoretical and practical SKGRs of the three methods, namely wireless channel based, one-way randomness and two-way randomness, are derived and compared. Simulation and estimation results show that the proposed TW method acquires a better performance not only in theory but also in practice, and the practical SKGR of TW method is time-linear which provides a feasible scheme to significantly improve the SKGR for quasi-static channel scenario.