In the counter-future where we, the dissidents and hackers, have control of technology, sending secret messages through blinkenlights can let us exchange information without being detected by dystopian leaders. By modulating light in a way that the human eye cannot see, this simple, yet clever, covert channel lets us hide in plain sight. To decode such transmissions, we must employ some sort of optical receiver.
Enter OpticSpy, an open source hardware module that captures, amplifies, and converts an optical signal from a visible or infrared light source into a digital form that can be analyzed or decoded with a computer. This presentation provides a brief history of covert channels and optical communications, explores the development process and operational details of OpticSpy, and gives a variety of demonstrations of the unit in action.