What do you do when you need to get data into an airgapped machine? On one, he soldered photoresistors to a couple of the keyboard matrix pins, such that they’d fire a keypress when lit up. He then placed the other keyboard PCB such that the Num Lock and Caps Lock LEDs are lined up with the photoresistors. This made it possible to have one PC flash the keyboard LEDs in order to “type” on the other machine. If you’ve been imagining creative ways to talk to airgapped computers, be sure to let us know on the tipsline!