PhotonKey: A key pairing system for IoT resource and input constrained devices using light sensors

Abstract

IoT environments are in need of key pairing protocols capable of operating within the unique constraints present, namely storage, processing, input, and power. In this paper, we present PhotonKey, a system designed to facilitate the generation of identical cryptographic keys for two resource and input-constrained IoT devices. These keys are derived from the devices’ individual observations of a public light event. Our contributions also extend to a custom, cost-effective hardware solution termed a ‘Synchronisation Machine’, which introduces synchronous rotation patterns to the light-sensing-capable devices during data collection with mechanical precision. This hardware solution serves the dual purpose of facilitating data collection and reducing adversarial capabilities. We evaluate the performance of our system using a large dataset comprising over 1000 samples, far surpassing the scale seen in related works. Finally, we demonstrate PhotonKey’s ability to produce statistically random bit-streams and achieve 0% equal error rates, even in the face of an ‘impossibly well-performing’ adversary.