I need a way to get usb thumb-drive securely recognized as a apple keyboard

Question

I posted this question over at Developer Discussions also, just to get more eyes on it, not to be disruptive.
So, I would like to utilize a maximum-length Admin. password (255 characters?) without having to manually type it in each time I login, install/update software, or for any other reason. The perfect situation would be some type of script or software installation onto a USB pen drive (2 gig sony)which is inserted into the macbook (via usb) when the Leopard Login screen appears. It logs me in, then, afterwards, it creates a clickable icon on the desktop that achieves the same goal (entering a long admin password securely). And all of the above is achieved using the built-in security of Keychain access, without having to continuously mount and unmount the drive.
Searching google produces many expensive products that do not fit: Securikey, omnikey, smart cards, tokends, and on and on. They seem to have figured this out at microsoft - not that it matters much, except that it appears to be possible.
One problem is that a USB thumb drive is not mounted until after login, it seems, but, I plugged in a friend's usb apple keyboard from the year 2000 and was able to type in my password at login. And, an email reply elsewhere suggested writing a daemon (that constantly runs in the background of the operating system) that could recognize the drive and accept a script from it that inputs the password and executes the 'enter' command.
I don't know how to write daemons yet, but I can stumble around a bit with bash and applescripts, and I can copy any Xcode project out of a book and make it run properly. I'm a beginner.
This project might create security issues for my operating system, but I'm really not concerned about that because this is a computer I don't rely on and can safely perform experiments on. And I would like to use this as an opportunity to learn - so I'm going to give it a whirl anyway - unless someone has already accomplished something similar. In that case, why reinvent the wheel and plug it into the wall, eh?
Basically I am asking for help. Any suggestions would be greatly appreciated.

Answer 1

You don't need to get deep into programming to do much of this.
launchd, the background process that's responsible for launching most of the background processes on your machine, has the ability to launch a script based on disk mount events.
StartOnMount <boolean>
This optional key causes the job to be started every time a filesystem is
mounted.
So you could create a LaunchDaemon script that watches for a disk mount. When a disk is inserted your script is fired off. You'd need to perform some verification to ensure the disk is, indeed, your USB stick and not some other device, then it can trigger the rest of the login process. Off hand I'd look to osascript to run an AppleScript-based keystroke, but there may be other ways, too.
One big question relates to securing your password. Clearly you can't store it in the script, so you'd have to read it from somewhere. You also can't store it on the USB stick unless you somehow encrypt it (otherwise someone can just look at the files on the USB stick and get your password), but AppleScript can use the keychain, too, although I'm not sure what keys would be available prior to login, so it requires some experimentation.