Even if you had to, it's still a bad idea. Ctrl+Alt+Delete works, because no normal Win32 app can intercept this - so if you do it, and you see a login box, you know that this is the real thing.
But any app can go fullscreen and draw a fake login screen that you can swipe up to show a fake login form.
But any app can go fullscreen and draw a fake login screen that you can swipe up to show a fake login form.