Galileo's Proposed Authentication Algorithm: Part 2 - Bert Hubert's writings

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.