There are extensions that do that well already. But the problem is still that I don't trust the browser with my private key. I wonder though how reasonable my

There are extensions that do that well already. But the problem is still that I don't trust the browser with my private key. I wonder though how reasonable my assumption is. E.g. how many security issues in the past two years could have potentially caused my key to be compromised if I were to use it that way.