MobiKey: Mobility-Based Secret Key Generation in Smart Home

Consumer Internet-of-Things platforms, especially in smart home, have received widespread attention. A large number of end-to-end and edge-to-end wireless communication links are subject to significant security and privacy risks. Key generation using radio link side-channel information is a burgeoning technology to solve this problem. This article designs a symmetric key generation method without environmental constraints, namely, MobiKey. The basic idea is taking the human mobility in home or the swing of the antenna to generate symmetric keys based on channel reciprocity. We leverage the practical phase information as the channel feature to generate symmetric keys between two communicating parties. To overcome the effects of noise on both communication sides and get a better performance, MobiKey harnesses the adaptive quantization method to make the bit generation rate and bit matching rate higher. MobiKey also uses the adaptive inconsecutive samples to increase the confusion of the adversary. Moreover, we propose the D-Gray code to enhance the randomness of quantization. MobiKey is implemented on different commercial devices, and the results show that it has comparative advantages in key generation consistency, randomness, and security. In addition, the performance in preventing predictable channel attacks and eavesdropping attack is discussed.