TEMPEST security: Protection against electromagnetic espionage

Invisible threats uncovered: TEMPEST security as a shield against digital leaks

Electronic equipment processes sensitive and classified information and sometimes unintentionally emits electromagnetic signals. Malicious actors can intercept and analyze these signals. This poses a serious security risk. Attackers can expose state secrets and sensitive information without physical access to the equipment.

From state secret to business-critical: Why TEMPEST security is indispensable in 2025

Without adequate TEMPEST protection, governments, military organizations, and companies handling classified information can fall victim to electromagnetic espionage. This leads to the leakage of state and corporate secrets, with severe consequences for national security and business continuity.

Working TEMPEST-proof: How to protect your organization against electromagnetic eavesdropping methods

National policy protects classified information against TEMPEST risks and records everything in document VBV 32000 (B). For NATO or EU-classified information, specific NATO or EU policy rules apply. Protective measures include shielding (such as Faraday cages), filtering of radio frequencies, and strategic placement of equipment.

How TEMPEST effectively blocks compromising emissions (signals)

Electronic devices emit unintentional electromagnetic signals that may contain sensitive information. These signals are called Compromising Emanations (CE). Intelligence agencies use techniques such as SIGINT (Signals Intelligence) to intercept and analyze these signals. SIGINT includes intercepting electronic communications, such as radio and mobile communications, to collect valuable intelligence.

TEMPEST uses three methods to reduce risky emissions and protect sensitive information from interception:

• Shielding: Devices are encased with materials that block electromagnetic radiation, similar to a Faraday cage, preventing signals from escaping and being intercepted by spies. This technique is essential in the design of TEMPEST-certified equipment and forms the basis of physical protection against electromagnetic leaks.
• Filtering: The use of electronic components that reduce or eliminate unwanted signals, such as special filters that only allow desired signals to pass and block noise or unwanted emissions, thereby reducing the risk of interception of sensitive information.
• Distance: Placing sensitive equipment farther away from potential eavesdropping equipment makes it more difficult to intercept signals. This can be achieved, for example, by arranging workspaces so that there are no direct lines to the outside where spies may have access. NATO defines different security zones (Zone 0, 1, and 2) that determine the level of TEMPEST protection needed, based on the minimum distance a potential attacker can reach.

TEMPEST A = Zone 0 within a protection distance of 1 meter

Areas where it is assumed that an attacker has almost direct access (about 1 meter distance). Equipment in this zone must meet Level A specifications. The delivery time for TEMPEST A products is approximately 12 to 16 weeks.

TEMPEST B = Zone 1 within a protection distance of 20 meters

Areas where an attacker is unlikely to come closer than 20 meters, or where building materials provide similar attenuation. Equipment in this zone must meet Level B specifications. The delivery time for TEMPEST B products is approximately 10 weeks.

TEMPEST C = Zone 2 within a protection distance of 100 meters

Areas where attackers face the equivalent of 100 meters of free-space attenuation, or similar attenuation by building materials. Equipment in this zone must meet Level C specifications. The delivery time for TEMPEST C products is approximately 6 to 8 weeks.