To understand EMSEC further there are a few more definitions that needs to be sorted out. These are first and foremost TEMPEST and electromagnetic emanations (also named leaking emanations).

Tempest is a NATO-certification that includes both protection against electromagnetic emanations and methods to spy upon others.

Electromagnetic emanations (leaking emanations)
Electromagnetic emanations refer to the electromagnetic radiations that all electric devices emit. If such radiations furthermore are disclosed, there is a risk that information that the radiations carry may leak out to unauthorized persons.

Generally we can also distinguish between two types of sources within electromagnetic emanations. These are:

1. Information source: The information that the electronic radiations carry
2. Physical source: The electric component/s that has generated the radiations

Depending on the type of 1) information source and 2) physical source, different forms of electromagnetic emanations are furthermore defined. Below are four common forms of electromagnetic emanations to be mindful of.

Connection through metallic line wires
Connection through metallic line wires mainly occurs and takes form in:

• Telephone wires and power lines
• Conduit pipes
• Other pipes and materials of concrete steele etc.Connection through metallic line wires usually occur at frequencies < 30 MHz. Such short-wave frequencies (also called high-frequency wavelengths) gives, with good conditions, audibility over very long distances.

Aerial Connections
An aerial connection instead occurs if linkages take form between two transmitting aerials. Frequencies are here limited to higher frequencies > 30 MHz. Electromagnetic crosstalks (which may create electromagnetic emanations through radio) is an example of a fully aerial connection.

To improve emission security and minimize the risk for electromagnetic emanations, one can take several actions. The various mechanisms can briefly be categorized as below:

Special equipment against electromagnetic emanations
Through special equipment one can either eliminate (Class 1 – U1) or limit (Class 2 – U2 or class 3 – U3) the risk for electromagnetic emanations. On Fibersystem we offer protection against electromagnetic emanations, Class 1 (U1).

Special rooms or cabinets to improve emission security
If equipment that carry sensitive information not is provided with its own protection against electromagnetic emanations, one can instead place it in a special room or in a cabinet. Such rooms contain walls that prevent electromagnetic signals to reach the outside world. Just as with equipment against electromagnetic emanations there are different degrees of such protection, where Security Class 1 (SS1) implies elimination of electromagnetic emanations and Sercurity Class 2 (SS2) implies limitation of it. Fibersystem has cabinets with protection, Security Class 1 (SS1).

Use of distance
By taking advantage of that radio frequency signals decrease with increased distance, one can use distance as a form of protection. By using natural forms of protection one can also reduce the risk of electromagnetic emanations. Some basic guidelines to improve emission security is for example that:

• Sensitive equipment should be placed in the inner part of the building.
• Sensitive equipment should be placed as close to the ground as possible, preferably under. Sensitive equipment can also be placed close to walls.
• Do not place equipment that carry sensitive information directly in front of a window.Please note that the above not should be considered as a substitute for protection, but rather as an additional precaution.

Electromagnetic emanations has for a long time been a strong threat against IT security. Historically, whole nations were them who had the capacity to carry out electromagnetic emanations and nations and their surrounding authorities therefore naturally became the prime target. As technology has become both cheaper and more available, it is though reasonable to assume that civil organizations can engage in reconnaissance and that their targets thus may be civil. Today, there are many commercial businesses that have begun to take steps to protect themselves against electromagnetic emanations.