PUF sensor: exploiting PUF unreliability for secure wireless sensing

Abstract

Wireless sensors are increasingly penetrating every domain of our lives through integration with Internet of Things, e.g., such devices are widely incorporated into smart buildings and for monitoring critical industrial infrastructure. Sensing, collecting and communication of sensor data, however, are under threat from various attacks due to the difficulty in implementing proper protection mechanisms and limited computational resources available in these cost-sensitive devices. This paper expands on recent research on physical unclonable function (PUF) sensors to secure sensing by taking the advantage of inherent physical randomness. In particular, PUF unreliability originates from its sensitivity to ambient parameter variations that is usually undesirable for elementary PUF applications-such as authentication and key generation-is exploited to guarantee the veracity of the sensed value. In this paper, a PUF naturally acting as a sensor or a PUF explicitly integrated with a sensor is called a PUF sensor. Security of sensing in a PUF sensor is attributed to the natural merging of cryptography and sensing to eschew the need for a standalone crypto module. Thus, the PUF sensor is appealing for low-cost applications. To obtain the sensed value, we develop an authenticated sensing protocol that is robust against eavesdropping, also capable of detecting man-in-the-middle manipulation of the sensed value. Compared to initial investigations of PUF sensors, we avoid the stringent requirements of a strong PUF. We validate the feasibility of the proposed authenticated sensing protocol based on an experimental implementation of a ring oscillator PUF sensor. To improve the sensing capability, we present an efficient approach to select sensitive responses and only employ them for sensing. Significantly improved efficacy is validated through comprehensive experimental results.