The tale of the spoofing of the White Rose of Drachs is an interesting case study in how the GPS/GNSS system actually works, and how these systems can be tricked with false data. The article published in IEEE Spectrum was written by Todd E. Humphreys of the University of Texas in Austin, and Mark L. Psiaki of Cornell University. In it, they explain the protocols in place to protect the two types of coded signals sent by the U.S. GPS constellation, civilian and encrypted military, and what it takes to fool a GPS receiver. Working different sides of the spoofing aisle, Humphreys is the spoofer who created a system for fooling GPS receivers, and Psiaki is the anti-spoof defender. Their chronicle of the lies that GPS can be made to tell is enlightening in lots of ways.
GPS spoofing is a real and present threat to navigation as the story of the White Rose of Drachs proves. But to keep things in proper perspective, spoofing of this level is beyond the abilities of most hackers. The White Rose was the willing subject of an intentional GPS spoof experiment, but even so, providing false but convincing GPS signals to the superyacht was not easy.
For satellite-based navigation to be successfully spoofed, the hacker has to:
- Be close enough to the target to determine its precise location,
- Log the four or more satellites the target’s GPS receiver is picking up signals from,
- Figure out the pseudorandom noise code (PRN) each satellite is broadcasting,
- Then transmit false PRN signals on a direct line-of-sight to the target.
Although the spoofer device used on the White Rose is too sophisticated for the “average” hacker to assemble, according to both Psiaki and Humphreys, the necessary technology is available in many countries. There are rumors of North Korea attempting GPS spoofing, and private individuals as well.
In addition to laying out the three major ways that GPS spoofing can be detected, another important point is made in this tale of spoofs, lies, and GPS. That is the need to build awareness of the vulnerability of many of our electronic systems to faked physical signals. As more unmanned and autonomous systems are planned and rolled out for testing in various communities, we must consider the question of the vulnerability of the sensors helping these systems to navigate safely and reliably.
One of the ways makers of unmanned and autonomous systems are working to mitigate such vulnerability is sensor fusion – the integration of multiple sources of positioning, control and navigation data within a single navigation system. Most autonomous and unmanned navigation systems use at least three sensors; these might include but are not limited to LiDAR, radar, Doppler Velocity radar, side scan sonar, cameras, GPS and inertial systems. The multiple sensors provide accurate, reliable and robust data, which makes the navigation system much harder to fool with fake GPS signals alone.
A leading designer and manufacturer of inertial measurement units (IMUs) and inertial navigation systems (INS), KVH helps the navigation systems of unmanned and autonomous platforms avoid falling for GPS lies with sensor fusion navigation solutions. The compact KVH GEO-FOG 3D and 3D Dual inertial navigation systems feature algorithms much more intelligent than typical Kalman filters, enabling navigation and control that’s intuitive and robust. KVH’s easy-to-integrate inertial systems are a go-to solution in navigation and control systems to overcome GPS vulnerability when signals are weak, jammed or unavailable.
For more about sensor fusion navigation solutions, watch the KVH Unmanned and Autonomous Webinar Series featuring experts in sensor fusion and navigation discussing subsea, aerial, and ground system autonomous navigation challenges.