Phenomenology TEMPEST
Electromagnetic spying – TEMPEST Risks, analysis, validation and standards

Here are the definitions of the main terms in the TEMPEST domain:

• TEMPEST Security Zone (TSZ): a zone in which permanent measures are taken to detect and prevent any espionage activity; this is the "controlled zone" within which it is guaranteed that a hostile individual is not present. The worst case, therefore, is when the hostile individual is at the boundary of the ZST;

• Red signal (SR): intentional electrical signal carrying sensitive information (necessarily located in the ZST), e.g. the "clear" signal of an encoder;

• Black signal (SN) : intentional electrical signal not carrying sensitive information, for example the "ciphered" signal...