A Low-Cost GPS Spoofing Detector Design for Internet of Things (IoT) Applications

The civilian Global Positioning System (GPS) is widely used for precise positioning, timekeeping, and synchronization in embedded systems. As a result, emerging digital infrastructure such as the Internet of Things (IoT) are dependent on GPS to locate and synchronize Things in the network. From a security perspective, civilian GPS signals are vulnerable to malintent because they are not encrypted and can easily be spoofed. Several countermeasures have been proposed to detect GPS spoofing attacks, but most of them require extensive signal processing capabilities and additional electronic components to capture and analyze RF signals. These add-ons may not be available to IoT devices, and if present, they will affect the device's power budget significantly. Therefore, new techniques for spoofing detection and survival are required before integrating GPS receivers with IoT devices and other critical infrastructures where energy and computation power are limited. In this work, we propose a novel GPS spoofing detection scheme based on hardware oscillators. Our design depends on measuring the frequency drift and offset of a free-running crystal oscillator with respect to the GPS signals. In our secure GPS spoofing detector design the trust is intrinsic, i.e., the receiver only trusts the on-board free running local oscillator. Intrinsic properties of these oscillators exhibit a strong correlation with the authentic GPS signals and any anomaly in this measurement will indicate potential attacks on the received GPS signals. This proposed design is cost-effective, secure, backward compatible with existing receivers, and does not require additional RF circuitry or network connection with other clocks for detecting attacks.