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Does Van Eck phreaking perform as described, i.e. allow a person to observe what is being displayed on a given computer screen (notably a LCD) from a distance without having any physical connection to the machine being monitored, and without the knowledge of the person being observed?

  • You can also try asking this at Information Security, some pros there have analyzed and/or designed these things - whether the phreaking attacks, or countermeasures such as Faraday cages. – AviD Jun 19 '11 at 9:27
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    It seems to me the linked Wikipedia page provides enough details about how exactly this works, including a link to the originla Van Eck paper. I am not sure what better answer do you expect to get? – Suma Aug 3 '11 at 19:48
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    With CRT monitors the screen image can sometimes be reconstructed just by observing the light levels in the room. – matt_black Jul 21 '12 at 12:50
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Yes it does. VGA or keyboard cable has side effect of acting as antenna.

Both eavesdropping and countermeasure techniques are widely knows as TEMPEST (which was codename used by NSA). It's described with details and numerous references here. Example from above source:

TEMPEST in action

It is standard to use TEMPEST protected terminals in military (NATO standard requirement), banks, embassies, government installations etc. The buildings themselves are usually also TEMPEST protected. TEMPEST protection of hardware is basically shielding equipment and cables with metal, which acts as Faraday cage. Which also has another side effect — it gives some protection against EMP attack.

BTW. the question gives away the answer. Van Eck's paper was published and peer reviewed.

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    "The paper was published and peer reviewed" is a very useful shorthand for saying "Not only was this treated seriously enough by a serious scientist to write it up for a serious academic journal, but other serious scientists took it seriously enough to try and knock holes in it and didn't find any noteworthy ones; this is as close to 'this is true' that you're going to get from a scientist." – Shadur Nov 19 '13 at 9:33
  • One wonders how this would work in a typical office with 15+ computers, screens, keyboards... – Benjol Nov 20 '13 at 12:33
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This video (2:10 onwards) shows Van Eck phreaking working with a CRT monitor, although it claims that the process works through the cable, not the monitor itself; if that is true, then it would work regardless of the display technology.

It also claims that keyboard data can be captured too. I find that difficult to believe.

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    I love how the video opens by referring to Van Eck phreaking as a "new type of cyber terrorism" despite the fact that Neal Stephenson uses it as a plot point in Cryptonomicon, which he wrote in 1999. – John Rhoades Jun 12 '11 at 14:09
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    @John Yea, I agree - it's quite typical of media hysteria. – Thomas O Jun 12 '11 at 14:12
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    @John it's worse than that, TEMPEST attacks / van eck phreaking have been known in the intelligence community since the 1950s and 60s. – Wedge Jun 12 '11 at 17:22
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    i thought this only worked with crt monitors because of the EM Signature giving off by the tubes cabling would give off much lower em fields and there fore harder to detect – Chris McGrath Nov 15 '11 at 22:21
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    Nah, it's easier with a CRT monitor because the monitor itself uses a very powerful magnetic field to bend the electron beam, and that field puts out a signal that's likely much easier to read at a distance, but even without that the cable still functions as an antenna. – Shadur Nov 19 '13 at 9:34

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