3 ms·

There was [earlier work](http://www.applied-math.org/optical_tempest.pdf http://www.applied-math.org/optical_tempest.pdf) on pulling Ethernet data from the LEDs

There was [earlier work](http://www.applied-math.org/optical_tempest.pdf http://www.applied-math.org/optical_tempest.pdf) on pulling Ethernet data from the LEDs of a 100MBps switch, as they were hard-wired to the cable. There was also a paper from around the same time about a keyboard hack that flashes the caps lock key imperceptibly fast but brightly enough so that a remote watcher can see the encoded keystrokes on your curtains or ceiling, but I can't seem to find that one.

zkms 9y ago
> a keyboard hack that flashes the caps lock key imperceptibly fast but brightly enough so that a remote watcher can see the encoded keystrokes on your curtains or ceiling, it's in that same paper you linked, page 20. Now the real beautiful result is the one where Kuhn deconvolves the diffuse light output (not an image, the total instantaneous light output, as would be collected by a fast photomultiplier tube or a photodiode) of a CRT with the impulse response of the phosphor -- to obtain the original image! https://www.cl.cam.ac.uk/~mgk25/ieee02-optical.pdf https://www.cl.cam.ac.uk/~mgk25/ieee02-optical.pdf