GNSS spoofing

2 Articles

A digital map is shown with a series of red waypoints making a roughly C-shaped curve. A smaller group of green waypoints stays stationary near one of the corners of the map.

Defeating Satellite Spoofing With Galileo’s Encryption

September 27, 2026 by 24 Comments

Considering how important it is for everything from navigation to keeping clocks in sync, satellite navigation systems are surprisingly vulnerable to a variety of attacks, ranging from simple jamming to more sophisticated spoofing attacks. This may be changing, though, as Galileo, Europe’s GNSS, recently demonstrated its first cryptographically-secured position fix under spoofing conditions.

Most GNSS systems, including GPS, have no verification measures to keep an adversary from transmitting a false signal at a higher power and hijacking a receiver; since GNSS signals are extremely weak by the time they reach the ground, this presents no great difficulty to a moderately well-equipped attacker.

Galileo’s Signal Authentication System (SAS) aims to fix this. The Galileo ground station pre-selects signal spreading codes, which it then encrypts with a regularly-changing secret key and publishes. A receiver which anticipates needing a verified signal can then download these encrypted codes ahead of time and store them. Galileo satellites then transmit on the E6-C pilot signal, and the receiver records the signal. After transmitting a message block, it then transmits the decryption key on a separate signal, which the receiver uses to recover the spreading codes. The receiver then correlates these spreading codes with the recorded signal to find the satellite’s pseudorange.

It’s a rather complicated system, but it works: earlier this month in Andøya, Norway, the annual Jammertest GNSS testing event took place. For one week, a wide range of organizations tested the resilience of their GNSS systems against various attacks, including jamming, delayed retransmission, and spoofing. Using five Galileo satellites, the European Space Agency was able to obtain a stable lock on their receiver even during spoofing.

In principle, this method could be extended to other GNSS systems. There’s certainly motivation to do so; very large-scale attacks have been demonstrated recently.

Knowing Your Place: The Implications Of GPS Spoofing And Jamming

May 23, 2022 by 31 Comments

Artificial satellites have transformed the world in many ways, not only in terms of relaying communication and for observing the planet in ways previously inconceivable, but also to enable incredibly accurate navigation. A so-called global navigation satellite system (GNSS), or satnav for short, uses the data provided by satellites to pin-point a position on the surface to within a few centimeters.

The US Global Positioning System (GPS) was the first GNSS, with satellites launched in 1978, albeit only available to civilians in a degraded accuracy mode. When full accuracy GPS was released to the public under the 1990s Clinton administration, it caused a surge in the uptake of satnav by the public, from fishing boats and merchant ships, to today’s navigation using nothing but a smartphone with its built-in GPS receiver.

Even so, there is a dark side to GNSS that expands beyond its military usage of guiding cruise missiles and kin to their target. This comes in the form of jamming and spoofing GNSS signals, which can hide illicit activities from monitoring systems and disrupt or disable an enemy’s systems during a war. Along with other forms of electronic warfare (EW), disrupting GNSS signals form a potent weapon that can render the most modern avionics and drone technology useless.

With this in mind, how significant is the threat from GNSS spoofing in particular, and what are the ways that this can be detected or counteracted?

Continue reading “Knowing Your Place: The Implications Of GPS Spoofing And Jamming” →