transient electromagnetic pulse emanation standard (Tempest)
Transient Electromagnetic Pulse Emanation Standard (TEMPEST) are security vulnerabilities caused by electromagnetic radiation. These are compromising radiation from devices, cables, and especially screens that can be intercepted and thus pose a potential risk to the user.
In general, any current flow generates electromagnetic fields that are radiated by cables or devices. In the case of cathode ray tubes(CRTs), this radiation is particularly high because the acceleration voltages for the electron beam are in the double- digit kilovolt range and cathode ray tubes have only a low shielding potential. This radiation can be detected and evaluated from a distance using appropriate receiving equipment such as spectrum analyzers. One then simultaneously sees the information on the screen that the user sees. This interception technique is called Tempest and applies in the same way to cables, devices, networks and systems.
Tempest is referred to in the literature as "Temporary Emanation and Spurious Transmission", but also as "transient electromagnetic pulse", as "Transient Electromagnetic Pulse Emanation Standard".
Various protection techniques exist against Tempest to increase emission reliability and limit compromising emission(KEM) from cables, systems, equipment and displays. These primarily include shielding, with material and sheet thickness playing a significant role. This gives the device or system an appropriate RF tightness. Tightness in this context requires slot plates that are closed without gaps and screwed together or overlapping. The outer sides, front, sides and rear panel must also be closed without gaps and overlaps. Cables must be shielded and the shielding must be properly grounded. EMC adhesive tapes, EMC seals, EMC insulating mats and ferrite beads for the live cables are available to prevent tempest.