Emanations
It has been shown that it is possible to surveil computers from a distance, with only commercially available equipment, by detecting the radiation emitted by the CRT monitor. This form of computer surveillance, known as TEMPEST, involves reading electromagnetic emanations from computing devices in order to extract data from them at distances of hundreds of meters.
IBM researchers have also found that, for most computer keyboards, each key emits a slightly different noise when pressed. The differences are individually identifiable under some conditions, and so it's possible to log key strokes without actually requiring logging software to run on the associated computer.
And it has also been shown, by Adi Shamir et al., that even the high frequency noise emitted by a CPU includes information about the instructions being executed.
Read more about this topic: Computer Surveillance
Famous quotes containing the word emanations:
“And so I look on those sentiments which make the glory of the human being, love, humility, faith, as being also the intimacy of Divinity in the atoms; and, that, as soon as the man is right, assurances and previsions emanate from the interior of his body and his mind; as, when flowers reach their ripeness, incence exhales from them, and, as a beautiful atmosphere is generated from the planet by the averaged emanations from all its rocks and soils.”
—Ralph Waldo Emerson (1803–1882)
“No man can tell but he that loves his children, how many delicious accents make a man’s heart dance in the pretty conversation of those dear pledges; their childishness, their stammering, their little angers, their innocence, their imperfections, their necessities, are so many little emanations of joy and comfort to him that delights in their persons and society.”
—Jeremy Taylor (1613–1667)