Definition - What does Emission Security (EMSEC) mean?
Emission security (EMSEC) is an analysis of a certain system's vulnerability to unauthorized access as a result of issues with electromagnetic emanations from hardware. Typically, emission security is applied to telecom systems, radio networks, cryptographic systems, or other similar communications installations. Emsec has developed over time as a critical part of protecting sensitive data in government or business operations.
Emission security may also be called emanation security.
Techopedia explains Emission Security (EMSEC)
The U.S. Department of Defense has responded to issues around emission security through the development of protocols to shield hardware and contain emanations. Virtually all hardware releases electromagnetic energy, and through this and other physical processes, there may be a risk of releasing data to unauthorized parties. Systems that meet DOD standards have been designed to be resistant to unauthorized access. The term TEMPEST is often used in a civilian context to describe emission security efforts, whereas military communications may be more likely to refer to EMSEC procedures.
More specific issues addressed by EMSEC include crosstalk from twisted pair cables, leakage from radio frequency signals, and anything else related to the interception of transmitted communications. Those studying emission or emanation security might study various kinds of "bugs" or eavesdropping equipment in order to understand how systems can be secured.