Emission security (EMSEC) is the protection of classified, sensitive, or proprietary information from being accessed by unauthorized parties through electronic emissions from systems or devices. It is a subfield of information security that deals specifically with the protection of electromagnetic emissions. These emissions can be intercepted and analyzed by third parties to gain sensitive information.
Electromagnetic emissions are the energy that is released by electronic systems and equipment in the form of electromagnetic radiation. They can be radio-frequency signals, visible light, infrared radiation, acoustic energy, or other form of electromagnetic energy.
Electromagnetic emissions are generated by all electronic systems, devices, and equipment as a by-product of their operation. For example, a mobile phone generates electromagnetic emissions in the form of RF signals when it communicates with a cell tower.
Emission security is implemented through a combination of physical, electrical, and software-based security measures: