OSNMAlib: An Open Python Library for Galileo OSNMA

Galileo has started authenticating its navigation message through OSNMA. In order to support OSNMA implementation by receiver manufacturers and application developers, this paper presents OSNMAlib, an open Python library implementing OSNMA functions. OSNMAlib processes the Galileo I/NAV pages in decoded SBF, hexadecimal or other formats, and performs the required operations to authenticate Galileo navigation data: OSNMA status handling, cryptographic functions required for the Merkle tree, digital signatures, keychain management and tag authentication. It handles the up-to-date data authentication status and performs the public key and chain renewal and revocation processes. This paper describes OSNMAlib architecture and its main functions and presents the first test results.