Sounds to me like they modified the driver so that it had some kind of emissions pattern they could track. Driver could be modified via a virus or something.
Let's say your computer emits a inaudible signal at 4.127Hz when the A key is pressed, 4.131Hz when the B key is pressed, etc. There is a unique signal emitted for each key.
It sounds like they just modified the driver to make those signals easier to detect. (i.e. A became 4Hz, B became 4.1Hz, etc.) If they had more sensitive detectors, maybe they wouldn't need to modify the driver.
It sounds like they just modified the driver to make those signals easier to detect. (i.e. A became 4Hz, B became 4.1Hz, etc.) If they had more sensitive detectors, maybe they wouldn't need to modify the driver.
My guess.