From The Economist
The sounds of typing can be decoded
Clattering keyboards may seem the white noise of the modern age, but they betray more information than unwary typists realise. Simply by analysing audio recordings of keyboard clatter, computer scientists can now reconstruct an accurate transcript of what was typed—including passwords. And in contrast to many types of computer espionage, the process is simple, requiring only a cheap microphone and a desktop computer.
Such snooping is possible because each key produces a characteristic click, shaped by its position on the keyboard, the vigour and hand position of the typist, and the type of keyboard used. But past attempts to decipher keyboard sounds were only modestly successful, requiring a training session in which the computer matched a known transcript to an audio recording of each key being struck. Thus schooled, the software could still identify only 80% of the characters in a different transcript of the same typist on the same machine. Furthermore, each new typist or keyboard required a fresh transcript and training session, limiting the method’s appeal to would-be hackers.
Now, in a blow to acoustic security, Doug Tygar and his colleagues at the University of California, Berkeley, have published details of an approach that reaches 96% accuracy, even without a labelled training transcript....