SYNCVIBE: Fast and Secure Device Pairing through Physical Vibration on Commodity Smartphones

The emergence of the Internet of Things (IoT) and pervasive computing challenges in securely and conveniently connecting devices with limited user interfaces. In particular, discovering and bootstrapping a wireless connection (e.g., Wi-Fi and Bluetooth Low Energy) between two devices that share no prior knowledge, commonly known as pairing, often requires users to go through cumbersome tasks of manually discovering the target device and entering a long passkey. When the devices do not have a proper user interface to enter a passkey, the security of pairing is often given up, leaving the communication vulnerable to a number of attacks. To alleviate this challenge, we propose a usable and secure out-of-band (OOB) communication method called SyncVibe, leveraging the inherent nature of close-proximity transmission of mechanical vibration. SyncVibe utilizes a vibration motor and an accelerometer, that are already ubiquitously available or easy to embed in mobile and wearable devices, to transmit and receive pairing information. By simply keeping two devices in direct contact, the user can bootstrap a secure, high-bandwidth wireless connection without manual pairing procedures. The proposed method maximizes accuracy and effective data throughput with a vibration clock recovery technique, which inserts a minimal amount of extra bit patterns to assure synchronization between the transmitter and the receiver. In addition, SyncVibe can automatically adjust its detection thresholds in response to various vibration noises and transmission media. Our implementation of SyncVibe demonstrates high-accuracy transmission, proving itself as a suitable OOB communication channel for short data transmission for secure device pairing.