Just as we carry out hand everywhere so that we can sign papers easily, each one of us should have a token or something equivalent that is based on PKI. And the

Just as we carry out hand everywhere so that we can sign papers easily, each one of us should have a token or something equivalent that is based on PKI. And then native OS drivers to add functionality to sign any file with it. Something like "Right-click" -> "Sign" for the signer, and then he either inserts the token (preferably a USB) and a biometric/password or swipes it on an NFC surface. And thus, the document is signed. Even with native OS drivers, I don't think there's a way to implement this for authentication without the help of an online "profile", which I personally hate because it tends to centralization of data, which in this case is NOT a good idea.