# Galileo's Proposed Authentication Algorithm: Part 2

DevFeed: [Galileo's Proposed Authentication Algorithm: Part 2](<https://devfeed.tech/articles/galileo-s-proposed-authentication-algorithm-part-2-36406.md>)

Original publisher: [Read original article](<https://berthub.eu/articles/posts/galileos-authentication-algorithm-part-2/>)

Published: 2020-08-26T08:43:09Z

Content type: article

Language: en

Sources: [Bert Hubert's writings](<https://devfeed.tech/sources/bert-hubert-s-writings.md>)

Topics: [Cryptography](<https://devfeed.tech/topics/cryptography.md>), [Authentication](<https://devfeed.tech/topics/authentication.md>), [Encryption](<https://devfeed.tech/topics/encryption.md>), [public key](<https://devfeed.tech/topics/public-key.md>), [Protocol (disambiguation)](<https://devfeed.tech/topics/protocol.md>), [navigation](<https://devfeed.tech/topics/navigation.md>)

Tags: [authentication](<https://devfeed.tech/tags/authentication.md>), [cryptographic](<https://devfeed.tech/tags/cryptographic.md>), [cryptography](<https://devfeed.tech/tags/cryptography.md>), [encryption](<https://devfeed.tech/tags/encryption.md>), [gnss](<https://devfeed.tech/tags/gnss.md>), [navigation](<https://devfeed.tech/tags/navigation.md>), [protocol](<https://devfeed.tech/tags/protocol.md>), [public-key](<https://devfeed.tech/tags/public-key.md>)

## AI overview

This second part explains how Galileo OSNMA uses delayed disclosure of symmetric cryptographic keys to let receivers verify earlier navigation-message signatures. It also discusses how the protocol fits authentication data into Galileo page and subframe structures.

## Source excerpt

Recapping from part 1: Galileo will soon add cryptographic signatures to the navigation messages. These cryptographic signatures are made with symmetric cryptography, which means clever techniques are required to prevent receivers from impersonating the network. The key to the technique is first signing messages, and only later disclosing the key used for the signatures, thus invalidating it for further use. Receivers can however verify that earlier signatures were indeed made with that key.