PGP. Register your official public key with the state. If you agree to a contract, sign it with your private key. State co-signs the key indicating with a short

PGP. Register your official public key with the state. If you agree to a contract, sign it with your private key. State co-signs the key indicating with a short validity period. State publishes list of person->key somewhere. Person signs multiple subkeys for different areas of their life. This could be made user friendly in a lot of ways... tap-to-sign with your smartwatch, boutique IOT pens, etc. We have the tech, but getting this secure system established would uphend a lot of industry players who have a vested interest in the current state of affairs.