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Vol. 1 · Ed. 2026
CyberGlossary
Entry № 1139

TEMPEST Attack

What is TEMPEST Attack?

TEMPEST AttackRecovery of secret information by capturing unintended electromagnetic, acoustic, or optical emanations from electronic equipment.


TEMPEST is an NSA codename and a family of side-channel attacks that recover sensitive information from compromising emanations leaking from monitors, keyboards, cables, power lines, and cryptographic devices. The classic case is van Eck phreaking, demonstrated in 1985, in which the electromagnetic emanations of a CRT or LCD display can be reconstructed at a distance to reveal the screen image. Modern variants extract AES and RSA keys from smartphones via electromagnetic probes, smartwatches, or even acoustic noise from CPUs. Mitigations are codified in standards such as NSTISSAM TEMPEST/1-92: shielded equipment and rooms (zoning), filtered power, separation distances, signal randomization, and constant-time implementations.

Examples

  1. 01

    Reconstructing the contents of a remote LCD by capturing its HDMI cable emanations.

  2. 02

    Extracting an RSA private key by measuring CPU electromagnetic leakage during signing.

Frequently asked questions

What is TEMPEST Attack?

Recovery of secret information by capturing unintended electromagnetic, acoustic, or optical emanations from electronic equipment. It belongs to the Cryptography category of cybersecurity.

What does TEMPEST Attack mean?

Recovery of secret information by capturing unintended electromagnetic, acoustic, or optical emanations from electronic equipment.

How does TEMPEST Attack work?

TEMPEST is an NSA codename and a family of side-channel attacks that recover sensitive information from compromising emanations leaking from monitors, keyboards, cables, power lines, and cryptographic devices. The classic case is van Eck phreaking, demonstrated in 1985, in which the electromagnetic emanations of a CRT or LCD display can be reconstructed at a distance to reveal the screen image. Modern variants extract AES and RSA keys from smartphones via electromagnetic probes, smartwatches, or even acoustic noise from CPUs. Mitigations are codified in standards such as NSTISSAM TEMPEST/1-92: shielded equipment and rooms (zoning), filtered power, separation distances, signal randomization, and constant-time implementations.

How do you defend against TEMPEST Attack?

Defences for TEMPEST Attack typically combine technical controls and operational practices, as detailed in the full definition above.

What are other names for TEMPEST Attack?

Common alternative names include: Van Eck phreaking, Compromising emanations.

Related terms