Secret key generation via random beamforming in stationary environment

Extracting secret key from the common randomness of wireless channel has gained significant interest as a mechanism for providing secure point-to-point communications. Current works focus on the methods of exploiting channel characterizations based on Received Signal Strength Indication (RSSI), channel phase and Channel Impulse Response (CIR) under different propagation environments. However, when the channel fading is static or quasi-static, the secret key bits derived from the channel may be identical or nearly identical. In this paper, we propose a method to solve this problem in multiple-input multiple-output (MIMO) systems based on random beamforming. Compared with single antenna systems, MIMO systems offer more randomness available. Furthermore we consider the worst scenario where the eavesdropper Eve knows perfect knowledge of the legitimate channel. The quantization error probability at Eve is simulated to assess the security of the proposed method.