Secure Over-The-Air Firmware Updates for Sensor Networks

Large-scale wireless sensor networks have been used in the Internet of Things (IoT) and other cyber-physical systems (CPS) to collect large amounts of data. One important practical issue in large-scale sensor networks is firmware updatesas updating many deployed sensors one by one is tedious. In this work, we study secure over-the-air (OTA) firmware updates for large-scale wireless sensor networks. We have designed a prototype system where a node can update the firmware in all nearby sensor nodes simultaneously. A custom bootloader is built for sensor nodes to either enter the update mode or boot into existing firmware. A one-way wireless protocol is designed to broadcast new firmware from one node to many other nodes. A shared key among the sensor nodes is used to encrypt/decrypt data packets and for authentication. The prototype system has been tested in ideal and non-ideal environments, where a node can receive the entire firmware in 2 and 5 rounds of transmissions, respectively.