Biblio

Context-based zero-interaction has become the trend for smart IoT device pairing. In this paper, we propose a secure and usable mechanism to authenticate devices co-located in smart home scenario, and build a secure communication channel between legitimate devices by utilizing on-board microphones to capture a common audio context. After receiving randomly generated sound signals, smart IoT device uses the time intervals between salient sound signals to derive audio fingerprint which can be matched among co-present devices and then be used to bootstrap trust of the devices. The protocol is based on the idea that devices co-located within a physical security boundary (e.g., single family house) can hear similar sounds, and the devices outside would miss parts of sound signals due to the attenuation when sounds pass through the wall. To accelerate the generation rate of audio fingerprint, an extra sound source is introduced. We implement our protocol on Android devices, and the experiment results show that the protocol can distinguish the malicious devices outside from the legitimate devices located inside a security boundary and can quickly establish a strong secret-key between legitimate devices.