Method and apparatus for masking acoustic keyboard emanations
One embodiment of the present invention provides a system that masks acoustic emanations from a keyboard. Upon receiving a signal indicating that a key on the keyboard has been pressed and/or released, the system generates a masking signal, and then outputs the masking signal to one or more audio transducers located in proximity to the keyboard, thereby masking acoustic emanations caused by the key being pressed and/or released.
1 . A method for masking acoustic emanations from a keyboard, comprising:
receiving a signal indicating that a key on the keyboard has been pressed and/or released; and
in response to the signal,
generating a masking signal, and
outputting the masking signal to one or more audio transducers located in proximity to the keyboard thereby masking acoustic emanations caused by the key being pressed and/or released.
2 . The method of claim 1 , wherein generating the masking signal involves generating an unpredictable audio signal.
3 . The method of claim 1 , wherein generating the unpredictable audio involves generating a randomized signal so that a different masking signal is generated each time a specific key is pressed and/or released.
4 . The method of claim 3 , wherein generating the randomized signal involves:
obtaining an acoustic signal caused by a given key being pressed and/or released; and
randomly modifying the acoustic signal to produce the masking signal.
5 . The method of claim 3 , wherein generating the randomized signal involves:
obtaining an acoustic signal which comprises a pulse of substantially constant amplitude; and
randomly modifying the acoustic signal to produce the masking signal.
6 . The method of claim 1 , wherein generating the masking signal involves generating an audio signal which will mislead an eavesdropper into thinking a different key was pressed and/or released.
7 . The method of claim 6 , wherein generating the audio signal which will mislead an eavesdropper involves generating a signal which is characteristic of a different key being pressed and/or released instead of the actual key that was pressed and/or released.
8 . The method of claim 1 ,
wherein the one or more audio transducers includes multiple speakers located in proximity to the keyboard; and
wherein generating the masking signal involves generating masking signals for the multiple speakers which spatially position the resulting sound so that the resulting sound appears to emanate from the vicinity of the key that was pressed and/or released.
9 . The method of claim 1 , further comprising enabling or disabling outputting of the masking signal based on a user-selectable preference.
10 . The method of claim 1 , wherein generating the masking signal involves:
generating the masking signal within a computing device which receives input from the keyboard; or
generating the masking signal within a computing engine which is integrated into the keyboard.
11 . The method of claim 1 , wherein the keyboard can include any type of data entry device or mechanism which has multiple keys or buttons.
12 . A method for masking acoustic emanations from a keyboard, comprising:
receiving a signal indicating that a key on the keyboard has been pressed and/or released; and
in response to the signal,
generating masking signals for multiple speakers located in proximity to the keyboard, and
outputting the masking signal to the multiple speakers thereby masking acoustic emanations caused by the key being pressed and/or released,
wherein the masking signals are generated to spatially position the resulting sound so that the resulting sound appears to emanate from the vicinity of the key that was pressed and/or released.
13 . The method of claim 12 , wherein generating the masking signal involves generating an unpredictable audio signal.
14 . The method of claim 13 , wherein generating the unpredictable audio signal involves generating a randomized signal so that a different masking signal is generated each time a specific key is pressed and/or released.
15 . The method of claim 12 , wherein generating the masking signal involves generating an audio signal which will mislead an eavesdropper into thinking a different key was pressed and/or released.
16 . The method of claim 15 , wherein generating the audio signal which will mislead an eavesdropper involves generating a signal which is characteristic of a different key being pressed and/or released instead of the actual key that was pressed and/or released.
17 . An apparatus which is configured to mask acoustic emanations from a keyboard associated with the computing device, comprising:
a computing engine;
an input to the computing engine configured receiving a signal indicating that a key on the keyboard has been pressed and/or released; and
wherein in response to the signal, the computing engine is configured to
generate a masking signal, and to
output the masking signal to one or more speakers located in proximity to the keyboard thereby masking acoustic emanations caused by the key being pressed and/or released.
18 . The apparatus of claim 17 , wherein while generating the masking signal the computing engine is configured to generate an unpredictable audio signal.
19 . The apparatus of claim 18 , wherein while generating the unpredictable audio signal the computing engine is configured to generate a randomized signal so that a different masking signal is generated each time a specific key is pressed and/or released.
20 . The apparatus of claim 19 , wherein while generating the masking signal the computing engine is configured to generate an audio signal which will mislead an eavesdropper into thinking a different key was pressed and/or released.
21 . The apparatus of claim 17 ,
wherein the one or more audio transducers includes multiple speakers located in proximity to the keyboard; and
wherein while generating the masking signal the computing engine is configured to generate masking signals for the multiple speakers which spatially position the resulting sound so that the resulting sound appears to emanate from the vicinity of the key that was pressed and/or released.
22 . The apparatus of claim 17 , wherein the computing engine is integrated into the keyboard.
23 . A computer-readable storage medium storing instructions that when executed by a computer cause the computer to perform a method for masking acoustic emanations from a keyboard, the method comprising:
receiving a signal indicating that a key on the keyboard has been pressed and/or released; and
in response to the signal,
generating a masking signal, and
outputting the masking signal to one or more audio transducers located in proximity to the keyboard thereby masking acoustic emanations caused by the key being pressed and/or released.
24 . The computer-readable storage medium of claim 23 , wherein generating the masking signal involves generating an unpredictable audio signal.
25 . The computer-readable storage medium of claim 24 , wherein generating the unpredictable signal involves generating a randomized signal so that a different masking signal is generated each time a specific key is pressed and/or released.
26 . The computer-readable storage medium of claim 23 , wherein generating the masking signal involves generating an audio signal which will mislead an eavesdropper into thinking a different key was pressed and/or released.