TEMPEST is a term used to describe a technology that deals with monitoring and protecting of equipment which emit electromagnetic radiation from unwanted reconstruction of intelligent data. Various measures are used to protect devises from this reconstruction of data. They include evaluation of sensitivity of information and the possibility of it being target for interception, control of persons to prevent unauthorized access to the devices or housing facilities, compartmentalization of information, and physical control of the devices (SANS Institute, 2010).
However, physical control of devises is emphasized. It is achieved in five ways as follows;
1. The area in which information is being processed is shielded so that electromagnetic emanations are prevented or specify distances beyond which the radiation cannot be sensed or detected. Quite often, the devices are put within metal casings (Faraday cage) which eliminate leakage of electromagnetic radiation. Vacuum seals are also common for prevention of sonic leakages. Sometimes, artificial high noise setting can be generated which can make sensing of the emanation extremely difficult. In addition, Radio Frequency Seals and honeycomb doors are applied to cabinets as well as chassis of devices (Kuhn & Anderson, 1998).
2. All the conductors are shielded to prevent leakage of emanations including network cables, telephone lines, power source, drains, cable trays, conduits, and pipes.
3. Transmission paths for both classified and unclassified devices must be separated to prevent any form of leakage across the cables. Power transmission lines for devices that are classified must be separated (McNamara, 2004).
4. Filtration of signals on electrical leads can help minimize electromagnetic signal/ emanation strength which can be achieved by applying ferrites and coupled filters. As such, power transmission lines have to be filtered.
5. All classified devices must be grounded properly and no earth ground station should be shared with another facility.
TEMPEST becomes an issue when the electromagnetic emanation is intercepted, interpreted and the information from data so obtained used maliciously. In this case, devices must be protected from stray emanation (Big Brother, 2000).
