*      What is van Eck Phreaking (the really short answer)?

*      van Eck phreaking is a form of electronic eavesdropping.  The eavesdropper (phreaker) uses a special setup to capture and display the images on someone’s monitor from a distance.


*      How about a slightly more involved answer?

*      When a cathode ray tube (CRT) monitor creates an image it does so by running the electron gun back and forth, as well as, up and down the screen.  This movement is done at a certain frequency. The intensity of the beam determines the color of pixel created.  This process result in the creation of a modular electro magnetic (EM) field.  Thus at any given moment the EM waveform will contain all the information represented on the screen.  Using an oscilloscope the EM waveform look irregular.  However, with the right decoding equipment one can turn the waveform back into a picture, thereby, duplicating someone else’s screen.


*      Why is it called van Eck phreaking?

*      In 1985 Dutch scientist Wim van Eck published a paper in Computer & Security called Electromagnetic Radiation from Video Display Units: An Eavesdropping Risk?  The paper (available here) details in rough terms how van Eck phreaking can be accomplished.  According to one account, van Eck displayed the effectiveness of his theories by taking a BBC crew around London and showing them what was on the screens of different companies.


*      What is phreaking?

*      According to one web page:


phreaking - /freek'ing/ "phone phreak"


1. The art and science of cracking the telephone network so as, for example, to make free long-distance calls.

2. By extension, security-cracking in any other context (especially, but not exclusively, on communications networks).

At one time phreaking was a semi-respectable activity among hackers; there was a gentleman's agreement that phreaking as an intellectual game and a form of exploration was OK, but serious theft of services was taboo. There was significant crossover between the hacker community and the hard-core phone phreaks who ran semi-underground networks of their own through such media as the legendary "TAP Newsletter".

This ethos began to break down in the mid-1980s as wider dissemination of the techniques put them in the hands of less responsible phreaks. Around the same time, changes in the phone network made old-style technical ingenuity less effective as a way of hacking it, so phreaking came to depend more on overtly criminal acts such as stealing phone-card numbers.

The crimes and punishments of gangs like the "414 group" turned that game very ugly. A few old-time hackers still phreak casually just to keep their hand in, but most these days have hardly even heard of "blue boxes" or any of the other paraphernalia of the great phreaks of yore.



*      So it is actually possible to do this?

*      Yes.  At Defcon IV, Jim Carter demonstrated a van Eck device.  Defcon is a conference targeted primarily at the hacking community.  Defcon IV occurred on July 26-28, 1996.  The link to the Defcon website is here.  The link to the Defcon IV announcement is here.


*      Can I do it?

*      Possibly, but probably not.  There are reports that a van Eck phreaking device can be made for under $5000, but good luck with that.


*      Well even a fool can realize that possessing van Eck technology can be dangerous to National Security.  Is there anything I should know about before I devote the rest of my life to espionage and creating neat spy devices with cool antennas?

*      One word: TEMPEST.


*      TEMPEST, an acronym for Transient Electromagnetic Pulse Emanation Standard is described as both “a specification for equipment and a term used to describe the process for preventing compromising emanations”



*      TEMPEST is classified as it is run by the National Security Agency (NSA).


*      A timeline of TEMPEST can be found here.  For more information on tempest click one of the following links:


*      Link 1

*      Link 2



*      How about a little information about protecting myself from van Eck phreakers?

*      One surefire way of protecting yourself from the prying van Eck eyes of others is by employing a Faraday cage.  A Faraday cage is an aperture-less enclosure constructed of a perfectly conducting material.


*      A Faraday cage will stop an electromagnetic waves created within from escaping (thereby protecting you and you monitor).  For a website on this concept go here.


*      How about something less… how do you say… big?

*      Well how about something so tiny it fits on a floppy?  Let me introduce you to Tinfoil Hat Linux.  Tinfoil Hat Linux is a bootable Linux distribution that fits on a floppy disk.  Despite it minimal functionality (due of course to the fact that it is so small it can fit on a floppy), it does provide a number of useful tools.  Among the tools provided are: protection against van Eck phreaking, protection against key logging, use of PGP keys, and the ability to read/write files. 


*      To the computer enthusiast: Tinfoil Hat Linux is really, really neat.  I would suggest simply trying it to experience it.  Besides which on today’s broadband internet access, downloading it takes all of… hmmm… 10 seconds?


*      For more information on Tinfoil Hat Linux, or to download the distribution itself, go to this website.


*      Tell me more! Tell me more! I’m a script kiddie wanting to be Elite and this could be my ticket.

*      Hacking for illegal purposes is bad.  Do not do it.  Do not play chicken with the law.  That is also bad. 


*      However, becoming less ignorant is good.  The best way to understand the concepts is to read van Eck’s papers and understand them.  A second van Eck paper is available here.


*      So this all sounds great in theory, but how can I be sure that all this van Eck stuff is really true?

*      So a skeptic needs proof?  Would using your monitor as a AM transmitter be convincing?

*      The software you require can be found here.  For more information on the specifics not contained in the file go to this website.


*      Note: This program does not work on Windows.



This site was constructed by Jonathan Grover for Upsilon Pi Epsilon at Johns Hopkins University.