A standard keylogger would do the trick, I guess: just store the timestamp along with the key pressed, register yourself to the OS as a keyboard device and then

A standard keylogger would do the trick, I guess: just store the timestamp along with the key pressed, register yourself to the OS as a keyboard device and then replay the keys back. How hard could that be? The only plausible response I can think of is to go the HDMI route and force keyboard manufacturers (and the OS) to only recognize cryptographically sound connections.