Electromagnetic shielding is one of the most important IT system security methods. Every device, including a computer, is a source of electromagnetic radiation.

Data flow generates electromagnetic radiation of a specified frequency, mainly through the monitor, both through a “traditional” tv screen or a laptop monitor. Emission of radiation also takes place through cables, sockets, ports, printers, scanners etc. The signal is emitted to the power grid which powers the computer.

Each of these signals carries informations which can be decrypted.

Computer radiation is strong enough to let a special, compact device pick it from a few hundred meters (up to a thousand). For such purpose, people use specially designed antennas and eg. Water networks, electricity, heating, and air conditioning conduits. Signals brought to the highly sensitive receiver are processed by appropriate software, and information are separated from the filtered noise; then converted to the computer programs of choice – which allow the data to be read – eg. Word.