Lol, you got me there. Yes, OK, if you have an operator standing by 24 hours a day to type in a long secret phrase which will not be stored on disk and will be

Lol, you got me there. Yes, OK, if you have an operator standing by 24 hours a day to type in a long secret phrase which will not be stored on disk and will be used as a salt in hashes stored by the system, and will infallibly ensure the server does not fall into the wrong hands in a running state, and there are no other attack vectors, then that is kind of secure. Since your system relies on a secret key, though, you may as well just use encryption in the first place rather than going to these absurd lengths to hammer hash functions into an encryption-shaped hole.