TEMPEST stands for “Telecommunications Electronics Materials Protected from Emanating Spurious Transmissions”. It is a U.S. National Security Agency (NSA) specification for protecting against data theft through the interception of electromagnetic radiation. Computers and other electronic devices emit radio frequency (RF) signals and electromagnetic radiation that cybercriminals can use to reconstruct intelligible data.
TEMPEST was the codename of a U.S. government project in the late 1960s that studied this threat. Today, it describes various techniques for preventing compromising emanations (CE). It includes strict requirements for the electromagnetic shielding of equipment, rooms, or even entire buildings. It also specifies distances between equipment and walls and building pipes and the space between cables carrying classified vs. unclassified information.
Types of Compromising Emanations
The NSA uses the term “RED baseband signals” to describe CE that could expose national security information (NSI). RED systems include all electronic equipment that processes NSI. BLACK systems process non-NSI data or data that has been encrypted.
RED baseband signals are attenuated, meaning they lose strength or become distorted due to distance, shielding, or other factors. They also exist outside of the device. For example, computer monitors emit electromagnetic radiation that can be intercepted and displayed on another monitor.
Other types of CE include:
- Line conduction. Signals that are unintentionally conducted or noise-induced over power lines, signal lines, etc.
- Intended signal modulation. Intended signals that are angle modulated or amplified.
- Acoustic. Sounds produced by keyboards, relays, and other mechanical devices that can be intercepted and interpreted.
TEMPEST Standards and Requirements
The RED vs. BLACK designation forms the basis of a TEMPEST security strategy. The first step is to separate systems, components, cables, and circuits that handle NSI in plain text from those that do not. The TEMPEST specifications can then be applied to the RED equipment to shield it from electromagnetic and RF radiation threats.
The distinction also helps ensure that BLACK equipment does not become a source of CE threats. For example, signals from RED cables can be unintentionally transmitted by nearby BLACK cables. Therefore, the two must be shielded or separated by adequate distance.
TEMPEST calls for the use of specially shielded devices for processing NSI. There are three categories of TEMPEST-shielded devices, ranging from highly secure equipment available only to U.S. government agencies and approved contractors to devices for general commercial use. However, TEMPEST devices are expensive and tend to lag behind current technology. In many cases, there is not a TEMPEST option for innovative applications.
Another approach is to shield the room that houses RED equipment. U.S. government agencies and contractors often use shielded rooms called SCIFs (Sensitive Compartmented Information Facilities) to protect equipment from eavesdropping.
Building out a SCIF is expensive, and the facility will require ongoing maintenance. When the goal is to shield IT equipment, a more cost-effective approach is to block electromagnetic emanations at the server rack level using copper, aluminum, and other materials. (Check out our blog about what materials block RF signals for more info.) Shielded racks also make it possible to isolate specific equipment and scale the installation by simply adding more racks.
The Enconnex Shielding Solution
Enconnex partners with best-in-class, government-approved manufacturers to deliver high-performance RF/EMI-shielded enclosure solutions. Designed to achieve significant signal attenuation across wide frequency ranges, these enclosures are available in both standard cabinet and wall-mounted configurations. They combine a compact, lightweight footprint with UL-listed construction, integrated thermal management, and flexible customization to meet the unique demands of each deployment. Connect with our team to explore how we can support your RF/EMI shielding requirements with proven, scalable solutions.
Contact Enconnex today to learn more.