In terms of zoo security, things are only just now reaching new highs. It was an antiquated system at best that contained even the most vicious animals. It’s interesting to look back in terms of how computer security evolved in order to ensure that nobody was able to reach into the minds of these computers and extract the data which governments were so carefully trying to protect.
Tempest is one response to what is slowly being recognized as a technological time bomb: loss of security in computer processing and information transmission systems.
The federal government, especially the military services, recognized more than two decades ago the danger of signal emanations from electronic equipment and the subsequent compromise of potentially sensitive data. Only in the last year or two, however, has private industry begun to look carefully at this explosive topic.
Consider that for less than $300 a reasonably clever technician can put together components bought from a popular electronics chain and be able to read computer screens within a mile or so, from almost any vantage point.
The intrusion device could be placed in a van, trailer or some other unobtrusive conveyance. It could monitor screen messages at random by successively scanning its targets. There would be no need for the device to decode anything, because it would be viewing, with no threat of detection, the same English-like messages the legitimate operator sees. This operator would not know screen images were being intercepted because the entire procedure relies on a simple fact: computers and their related peripherals indiscriminately disseminate information over radio frequencies.
There is no way to change the natural emission of radiation by computing components, but something can be done to stifle the emanations.
That something is Tempest technology. Tempest products constitute one of the hotter niche enterprises today. They include documentation, procedures, monitoring and systems that block potentially revealing emanations. Due to the sensitive nature of the Tempest program, many implementation details cannot be divulged. But there is enough general information and unclassified data to reveal its growing importance both in and outside the federal government.
Reducing and Shielding Signals
Control of compromising electromagnetic or acoustic emanations can be accomplished either by reducing signal levels or by shielding the radiation they produce.
In earlier years, the teletype was one of the prime emanators. Eventually a low-level signal teletype was developed. Today, power lines and signal lines carrying clear, unencrypted text are protected by means of shielding. Lines entering and exiting a “red” (unencrypted, but still classified) area are filtered or isolated to prevent clear text from being transmitted to the outside. Clear text is encrypted before external transmission. Fiber optics often are used to isolate signal lines between adjacent cabinets.
In data processing, Tempest devices traditionally have included peripherals, communications equipment and, more recently, personal computers. Large-scale computers are protected by shielded enclosures for economic reasons. It is simply too expensive to Tempest-certify large mainframes.
Equipment must be installed properly to ensure Tempest integrity. NACSIM 5203, Guidelines for Facility Design and Red/ Black installation, addresses this requirement for the Defense Department.
After installation, a facility is “swept.” Tempest teams visit a facility to measure emanation levels. Only after levels are sufficiently low is the facility approved for operation.
Ergonomics, or human engineering, also affects Tempest equipment. Source-suppression techniques are preferable to shielded enclosures so that switches, buttons, keys and other controls can remain unencumbered by boxes.”
Cashin, Jerry. “Focus on Tempest products.” Government Computer News 16 Jan. 1987: 21+.
In other words, shielding signals was one of the biggest ways that computer security advanced in the 1980’s. Included in that were zoos and other containment facilities. Imagine a Jurassic Park esque breakout because of a hacker such as Dennis Nedry.