The public-key encryption method makes it possible to ensure the integrity of my data without having to give my private key to a large number of people. But how do you know if the information we receive from someone is really sent by that person?

This is done by the PGP encryption system, where the public key is made available in a public database and other participants can verify the sender using the signature. In large companies and in security-critical areas PGP is now automatically integrated.