TriNetre - Archive for December 20, 2004

(no longer updated)

Dmitri Asonov and Rakesh Agrawal from IBM Research have shown in the paper "Keyboard Acoustic Emanations" [pdf] that they are able to differentiate the sounds emanated by different keys of a PC keyboards, notebook keyboards, telephones and ATM pads and hence attacks based on this are possible.

They used a simple PC microphone for short distances of 1 meter and a parabolic microphone for distances upto 15 meters A neural network system was trained to classify the clicks. Experiments found that at short distance, only 0.5 incorrect recognitions were made per 20 clicks. Not too surprisingly, this rate did not vary when the distance was increased.

The authors think that the reason for the distinguishable sound is because different parts of the keyboard plate might produce different sounds when the nearby key is pushed. "By analogy with a drum, striking a key at different locations on the plastic plate provides different timbres."