Information concerning semi-mythical electromagnetic computer monitoring technology developed by the US government has been uncovered by Cypherpunks, an American technology activism group.
The technology, Tempest, supposedly allows computer activity to be monitored remotely according to electromagnetic radiation emanations. Tempest has long been rumoured although no concrete proof of it has ever been discovered.
Cypherpunks claims to have obtained information concerning Tempest from the US National Security Agency (NSA) through the freedom of information act and have published the information online .
This page also contains correspondences between representatives of the Cypherpunks the NSA concerning revealing details about Tempest under the stipulations of the Freedom of Information Act.
Evidence of the once top-secret nature of the information can be found in the opening few paragraphs which contain the statement, "No person is entitled to possess or access information concerning compromising emanations solely because of his office, position, or type of clearance.
"No information related to the subject of compromising emanations shall be released to the public through the press, advertising, radio, TV, or other public media without specific written approval from the Director, National Security Agency."
Cypherpunk has long publicised information about Tempest and for those keen to stop the government watching them play Quake, an unofficial Web page containing details of how to protect a computer from electromagnetic detection can be found here .