Galileo’s Authenticated Position Fix
In contrast to other GNSS Galileo has an additional feature called Open Service Navigation Message Authentication (OSNMA). OSNMA allows the authentication and validity of information broadcasted by Galileo satellites.
All GNSS are vulnerable for manipulation of their signals and the information transmitted with those signals. In recent years more cases of intentional malicious manipulation of signals have been reported especially in critical areas such as disputed international borders and military / economic conflict zones. Results are often completely wrong position information delivered by navigation equipment. The reported cases include travel path’ of ships on land and strange travel patterns such as circles for all vessels in the area. While those detections have been obvious other cases might cause serious disasters when not detected during maneuvers.
The Galileo navigation satellite system has the authentication feature in its design for along time. Within recent years the feature has been pushed forward and an in-orbit test has been conducted. While hardware encryption would require changes to satellites and user equipment the authorities are opting for a pure digital solution which would allow rollouts through software updates.
The major obstacle for authentication of broadcasted information is the constraint digital transmission possibilities within the satellite signals. Basically the satellite is transmitting a delayed authentication tag within 30 seconds which allows the receiving position device to validate the origin of the information. The testing was performed at ESA’s Navigation Laboratory using a two-hour window with eight visible Galileo satellites on November 18, 2020.
(Source: GPSworld accessed Mar 17, 2021)