Five researchers from the University of Michigan have published a research paper in which they provide the technical concept of a hidden backdoor introduced not in software, but at the hardware level, where it is difficult to detect.
The scientists describe their backdoor as a rogue component hidden in the chip's thousands of similar components. Most of these work as on/off switches, "on" being a binary 1, and "off" being a binary 0, the basic code for all digital devices.
Instead of turning on or off like a transistor, the rogue component would work as a capacitor, a wolf in sheep's clothing. The capacitor would store energy with every new command it receives.
