22I am reminded of an example from the world of “smart” mobile telephones, commonly equipped with accelerometer sensors for detecting physical orientation. Accelerometers detect the force of acceleration and of gravity, and are useful for a variety of convenient “apps” having nothing to do with telephony. Smart phone manufacturers include such sensors in their mobile devices and link those sensors to the phone’s operating system because doing so permits innovative applications, which in turn makes the product more desirable to application developers and ultimately consumers. It was discovered, though, that the signals generated by these accelerometers could be used to detect “keystrokes” made by the user, the sensors picking up vibrations made as the user taps their finger against the glass touch-screen of the smart phone. With the right signal processing, the accelerometers’ signals could be combined in such a way to identify which characters the user was tapping on the virtual keyboard, and thereby eavesdrop on their text-based communications!