Reconfigurable Intelligent Surface Speeds up MIMO Secret Key Generation

Recently, there is a growing interest in employing reconfigurable intelligent surface (RIS) to assist physical layer key generation in wireless networks. However, current works only studied the RIS-aided key generation schemes in SISO (single-input-single-output) communications, which have relatively low key generation rate (KGR). Therefore, here, in order to fill this gap, we propose the new and really novel RIS-aided MIMO (multiple-input-multiple-output) key generation scheme. By fully exploring the reflection signals from the RIS to the legitimate communication partners as the introduced, controllable and artificial randomness, combined with the spatial degree-of-freedom of RIS and MIMO incident and reflected signals, the KGR performance can be significantly improved. The information theoretical security is fully investigated, and the upper bound value of KGR is derived to comprehensively evaluate the system performance. The simulations fully validate the effectiveness and robustness of the proposed new and really novel, and interesting scheme.