Hacking Typewriters

The State Department has opened a new exhibit that displays the technology that Cold War-era spies used to eavesdrop to listen in on top-secret conversations or steal sensitive information. Scientific American has a brief writeup on the exhibit and slide show.

One of the more interesting electronic eavesdropping devices sounds like a popular hacking techniques hackers use on PCs today to steal passwords, bank account numbers and other sensitive information. It's called keystroke logging. "Because the Selectric coupled a motor to a mechanical assembly, pressing different keys caused the motor to draw different amounts of current specific to each key," according to a State Department brochure promoting the exhibit. "By closely measuring the current used by the typewriter, it was possible to determine what was being typed on the machine."

State was on to the practice. In what could be described as a patch, the agency masked the electric pulses with "inertia" motors that absorbed the stress on the motor, masking the amount of electricity it was drawing. Not sure if there is an analogous solution for PCs.