Septentrio adds OSNMA anti-spoofing security to GNSS receivers -

Septentrio adds OSNMA anti-spoofing security to GNSS receivers

Falsification of GNSS signals can seriously impact any application relying on precise navigation and timing synchronization. OSNMA contributes to increasing the resilience of civil GNSS signals against such possible threats.


GNSS solution provider Septentrio has added OSNMA anti-spoofing security to its mosaic GNSS receiver modules. The OSNMA (Open Service Navigation Message Authentication) is a freely accessible data authentication function for the Galileo Open Service worldwide and provides receivers a first level of protection against falsifying, or spoofing, the Galileo Open Service, assuming that the receiver fulfils a set of requirements. This is realized by transmitting authentication specific data in previously reserved fields of the E1 I/NAV message.

Septentrio’s mosaic-X5 GNSS receiver module. (Image: Septentrio)

The aim of OSNMA is to improve confidence on the user side by enabling the user to verify the authenticity of the Galileo navigation parameters required for positioning, navigation and timing (PNT).

Septentrio said it has been working closely over the last two years with ESA (European Space Agency) during the test phases of OSNMA deployment, and the knowledge gained during this period allowed it to bring this advanced security capability into its modules.

Spoofing is a malicious form of radio interference, where faulty positioning information is sent into the receiver. The falsification of GNSS signals can have a serious impact on any application that relies on precise navigation and timing synchronization – from aviation and maritime to drones. The ESA said OSNMA is suitable for a wide range of users and contributes to increasing the resilience of civil GNSS signals against such possible threats, to confirm the authenticity of the Galileo navigation data.

The anti-spoofing capability of OSNMA complements Septentrio’s advanced interference mitigation technology, AIM+, and strengthens the overall security of Septentrio GNSS receivers, making them suitable for assured PNT solutions as well as critical infrastructure, such as 5G network synchronization.

The head of product management at Septentrio, François Freulon, said “Our close collaboration with ESA enabled us to get the expertise needed to implement and validate this functionality in a timely manner. The addition of OSNMA to Septentrio’s already strong anti-jamming and anti-spoofing technology, takes our receivers to a new level as the market leader of resilient positioning and timing solutions for industrial applications and critical infrastructure. “

OSNMA is now supported by the company’s complete mosaic receiver family including GNSS RTK positioning modules, timing modules and heading receiver modules. It will also be rolled out on Septentrio’s latest generation of OEM receiver boards, AsteRx-m3, and subsequently on the ruggedized boxed receivers.

How does OSNMA work to enable anti-spoofing?

The OSNMA service secures Galileo signals against spoofing by enabling authentication of navigation data, which carries information about satellite location. If navigation data information is modified, this would result in erroneous positioning calculation.

 A cryptographic algorithm in an OSNMA-enabled GNSS receiver authenticates Galileo OSNMA signals. (Image: Septentrio)

OSNMA utilizes a hybrid symmetric/asymmetric cryptography technique. A secret key on the satellite is used to generate a digital signature. Then both signature and key are appended to the navigation data and transmitted to the receiver. A sophisticated algorithm within the OSNMA-enabled receiver uses a public key to check the authenticity of the transmitted key. It then uses the transmitted key and the digital signature to check the authenticity of the navigation data. If a satellite signal is flagged as spoofed, it is excluded from the positioning calculation.

OSNMA is designed to be backwards compatible, so that positioning without OSNMA will still work.

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