Van Eck phreaking

Van Eck phreaking is the process of eavesdropping on the contents of a CRT display by detecting its electromagnetic emissions. It is named after Dutch computer researcher Wim van Eck, who in 1985 published the first paper on it, including proof of concept.cite journal | author=Van Eck, Wim | title=Electromagnetic Radiation from Video Display Units: An Eavesdropping Risk? | journal=Computers & Security | volume=4 | year=1985 | pages=269–286 | url=http://jya.com/emr.pdf | doi=10.1016/0167-4048(85)90046-X ]
Phreaking is the process of exploiting telephone networks, used here because of its connection to eavesdropping.

Van Eck phreaking might also be used to compromise the secrecy of the votes in an election using electronic voting. This caused the Dutch government to ban the use of NewVote computer voting machines manufactured by SDU in the 2006 national elections, under the belief that ballot information might not be kept secret. [ [http://www.iht.com/articles/ap/2006/10/30/europe/EU_GEN_Netherlands_Voting_Machines.php Dutch government scraps plans to use voting computers in 35 cities including Amsterdam (Herald tribune, 30. October 2006)] ] [ [http://www.heise.de/english/newsticker/news/80302 Use of SDU voting computers banned during Dutch general elections] (Heise, October 31. 2006)]

Basic principle

Information that drives the video display takes the form of high frequency electrical signals. These oscillating electric currents create electromagnetic radiation in the RF range. These radio emissions are correlated to the video image being displayed, so, in theory, they can be used to recover the displayed image.

CRTs

In a CRT the image is generated by an electron beam that sweeps back and forth along the screen. The electron beam excites the phosphor coating on the monitor glass and causes it to . The beam intensity determines the intensity of the pixel (see CRT for a detailed description). The electron beam is deflected by several electromagnetic coils. The voltage in the coils is modulated at a high frequency and contains information related to the video image. (Error: These coils carry signals controlling beam deflection only, not beam intensity modulation, and can not, in principle, radiate any video display information.) These high frequency, high voltage signals create electromagnetic radiation that has, according to Van Eck, "a remarkable resemblance to a broadcast TV signal". What these radiated signals lack is the synchronizing portion of the TV signal. (The deflection coils mentioned above would emit "only" synchronization signals. The vertical sync is so low-frequency that its probably would not be significantly detectable and would have to be externally recreated.) By supplying external synchronization, the radiated signal can be displayed on another television.

In the paper, Van Eck reports that in February 1985 a successful test of this concept was carried out with the cooperation of the BBC. Using a van filled with electronic equipment and equipped with a VHF antenna array, they were able to eavesdrop from a "large distance".

LCDs

In April 2004 new academic research has revealed that flat screens and laptop displays are also vulnerable to an FPGA-driven electromagnetic eavesdropping. The required equipment for espionage was constructed in a university lab for less than 2000 US dollars.cite journal | author = Kuhn, M.G. | year = 2004 | title = Electromagnetic Eavesdropping Risks of Flat-Panel Displays | journal = 4th Workshop on Privacy Enhancing Technologies | pages = 23–25 | url = http://www.cl.cam.ac.uk/~mgk25/pet2004-fpd.pdf ]

Countermeasures

Countermeasures are detailed in the article on TEMPEST, the NSA's standard on spy-proofing digital equipment. One countermeasure involves shielding the equipment to minimize electromagnetic emissions. Another method, specifically for video information, scrambles the signals such that the image is perceptually undisturbed, but the emissions are harder to reverse engineer into images. Examples of this include low pass filtering fonts and randomizing the least significant bit of the video data information.

Limited use

Van Eck phreaking potentially offers non-proximate eavesdropping options without the interested person having to compromise the affected system's hardware or software. Some may dismiss this possibility as the domain of "tin-foil hat" wearers, but Wim van Eck himself demonstrated a working model of this technology for a paltry $15 in 1985.

In popular culture

*In Neal Stephenson's 1999 novel "Cryptonomicon", Van Eck phreaking (of a laptop LCD) serves as a significant plot device.
*Van Eck phreaking was referenced directly in the "Numb3rs" season one episode "Sacrifice", on an LCD flat screen rather than a CRT monitor.
*Phillip Finch's 1995 novel "f2f" features the main character Ellis Hoile building a Van Eck scanner, and the device is used to finalize the plot of the book.
*In a fifth season episode of "Alias", a character suggests that they use Van Eck phreaking.
* Is often referred to in Charles Stross' novel "The Atrocity Archives" as a danger when viewing classified information.

ee also

* TEMPEST--(US government standards for limiting electric or electromagnetic radiation emanations from electronic equipment)
* RINT--(Radiation INTelligence, military application)
* Election fraud

References

External links

* [http://upe.acm.jhu.edu/websites/Jon_Grover/page2.htm Van Eck phreaking]
* [http://www.erikyyy.de/tempest/ Tempest for Eliza] is a program that uses your computer monitor to send out AM radio signals. You can then hear computer generated music in your radio.
* [http://www.lightbluetouchpaper.org/2006/03/09/video-eavesdropping-demo-at-cebit-2006/ Video eavesdropping demo at CeBIT 2006] by a Cambridge University security researcher
* [http://eckbox.sourceforge.net eckbox] – unsuccessful or abandoned attempt in spring 2004 to build an open-source Van Eck phreaking implementation