Detect Computer Serial Number?

I’m trying to come up with a more secure method of password protection than simply comparing an input text field with a predetermined password.

The client want to be able to prevent the user from sharing the application with others on different computers.

Is there a way for Flash to detect a computer’s serial number, or other unique ID?

Something similar to:

myButton.onRelease=function(){
computer = System.capabilities.os;
trace(computer);
}

I’m intrigued with the above System.capabilities.os function, but that just spits out the user’s OS version, and this approach needs something more unique.

Any ideas?