ESP32-based Multi-User Secret Key Generation System

This paper proposes a multi-user secret key generation system using off-the-shelf ESP32 modules. We first propose a new differential quantization algorithm and contrast the features of differential quantization with uniform quantization and existing equal-probability quantization. Then, we propose a differential compensation algorithm, which can effectively improve the randomness of differential quantization. The improved randomness is higher than that of equal-probability quantization, and the key disagreement rate (KDR) is lower than that of equal-probability quantization. After that, we create an ESP32-based multi-user secret key generation system. We compare the differences of KDR in three movement modes, stable, people-move and trolly-move, and in two scenarios, line-of-sight (LOS) and non-line-of-sight (NLOS). The results show that the KDR with third-order quantization is less than 0.1 for the LOS scene and less than 0.15 for the NLOS scene.