One of our favorite hardware hackers, Joe Grand, has shared slides and hardware designs from his recent B-Sides PDX talk:

Optical Covert Channels

Data exfiltration from a device is usually achieved over the network, via hardware implant, or by manipulating the characteristics of an internal electronic component. Optical covert channels transmit data using visible light in a method undetectable to the human eye.

Joe demonstrates using an optical receiver to capture data transmitted through a LED:

joegrand has shared the receiver boards on OSH Park:

OpticSpy Digital (Rev. A)

digital version using Everlight PLR135/T9 Fiber Optic Receiver

OpticSpy Analog (Rev. A)

analog version based on Maxim Integrated’s AN1117 application note: