Editing Acoustic cryptanalysis (section)

== Countermeasures ==
This kind of cryptanalysis can be defeated by generating sounds that are in the same spectrum and same form as keypresses. If sounds of actual keypresses are randomly replayed, it may be possible to totally defeat such kinds of attacks. It is advisable to use at least 5 different recorded variations (36 x 5 = 180 variations) for each keypress to get around the issue of [[Fast Fourier transform|FFT]] fingerprinting.<ref name=Asonov>{{citation | title = Keyboard Acoustic Emanations | last1 = Asonov | first2 = Rakesh | last2 = Agrawal | work = IBM Almaden Research Center | year = 2004 | url = http://rakesh.agrawal-family.com/papers/ssp04kba.pdf | first1 = Dmitri | access-date = 2007-05-08 | archive-url = https://web.archive.org/web/20120227213345/http://rakesh.agrawal-family.com/papers/ssp04kba.pdf | archive-date = 2012-02-27 | url-status = dead }}</ref>  Alternatively, [[white noise]] of a sufficient volume (which may be simpler to generate for playback) will also mask the acoustic emanations of individual keypresses.