Silence on the Wire

Preventing Blinkenlights Data Disclosure—and Why It Will Fail

The easiest solution to the problem, and one suggested by the original research, is pulse stretching—a practice intended to distort the blinks on an indicator by prolonging some of them, thus making any practical data recovery seemingly not feasible. Pulse stretching circuits are a group of fairly trivial devices that extend the duration of an encountered “high” input signal for an additional period of time. Most basic pulse stretcher design relies on a capacitor that charges in the presence of an input signal and then discharges slowly. This capacitor is connected to a binary discriminator, which is not a nickname for a vicious wrestling champion, but rather a device that converts ...