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Galileo OSNMA

galileo-osnma is a Rust implementation of the Galileo OSNMA (Open Service Navigation Message Authentication) protocol. This protocol is used by the Galileo GNSS to sign cryptographically the navigation message data transmitted by its satellites, in order to prevent spoofing. Briefly speaking, galileo-osnma can process the navigation message data and OSNMA cryptographic data and check all the cryptographic signatures against the ECDSA public key, in order to check the authenticity of the navigation data.

This library provides an Osnma struct that implements the OSNMA authentication as a black box. A user can feed data from INAV pages into Osnma and then request authenticated navigation data. Additionally, lower level functionalities of the OSNMA protocol are accessible in case finer control is needed.

This crate does not depend on std and can be used in small embedded microcontrollers. An example of this is given in the osnma-longan-nano crate.


The galileo-osnma crate makes extensive use of the log crate to log events related to the processing of the messages and the cryptographic functions.

Galmon integration

When this crate is built with the galmon feature, a galmon module is available, which can be used to read data using the Galmon transport protocol. The reader can be used to obtain INAV frames and OSNMA data from the Galmon tools, such as ubxtool.

An example of this functionality is given in galmon-osnma. This is a binary tool that reads data from the standard input using the Galmon transport protocol, and runs it through the Osnma black box, logging all the events that happen. See the quick start instructions about how to use this tool.


When built with the default features, the crate does not require std. Additionally, the crate supports the following features:

  • galmon. This enables support for reading the Galmon transport protocol and requires std.


Message bit fields.

DSM message collection.

Galmon integration.

MACK message storage.

Navigation message storage and handling.

OSNMA storage definitions.

Subframe collection.

TESLA keys and chain parameters.

Types used in galileo_osnma.

Validation status.


GST (Galileo System Time)

OSNMA “black box” processing.

Galileo SVN.

SVN construction error.

Type Definitions

Time of week.

Galileo week number.