Bill Gates revealed in a recent interview at Harvard University that requiring three keys--the ubiquitous CTRL-ALT-DEL combination--to log into Microsoft Windows was a "mistake." If that's true, it was a very serendipitous mistake, and one that we should all be thankful for.
Why? Because, as insecure as some perceive the Windows operating system to be, it could have been a thousand times worse if there were no keyboard interaction required to log on. That physical interaction tells the computer that you want to interface with the Microsoft Windows operating system, and ensures that rogue or spoofed software can't dupe users into typing usernames and passwords.
The graphical identification and authentication (GINA) library was an element of early versions of the Windows operating system that loaded almost immediately when the PC is powered up. The GINA was responsible for registering the CTRL-ALT-DEL sequence with the PC hardware at a very low level to ensure that key sequence could only be directed to the Windows logon screen.
In Windows Vista and later versions, GINA has been replaced by a more flexible system of Credential Providers, but the general purpose is still the same--to handle some sort of secure attention sequence (like Ctrl-Alt-Del) that signals the computer to direct to the Windows logon.
To his credit, Bill Gates seems to have recognized the need for there to be some sort of physical interaction required to log in. Gates, however, wanted it to be a single, designated key--perhaps something like the Windows logo key now found on virtually every PC keyboard.
The problem with Bill Gates single-key plan is that in most versions of Windows pressing the Ctrl-Alt-Del combination while Windows is running forces the OS to restart, or soft boot. It's pretty hard to "accidentally" press Ctrl-Alt-Del twice, but it would probably be trivial to tap the Bill Gates "magic key" a couple times and reboot your system--most likely when it's least convenient, and you're in the middle of a project with a deadline approaching in an hour and you end up losing all of your work.
So, thank you, Mr. Gates. Thank you for allowing the "mistake" of the three-key Ctrl-Alt-Del combination to become engrained as a Windows standard. That single key solution would have been a nightmare.