1. Context

1.1 The origins of electromagnetic anticompromission

The term TEMPEST refers to the fight against compromise of electromagnetic origin (hence its other name, "electromagnetic anticompromission"); it refers to electromagnetic disturbances (radiated and conducted emissions) from electronic equipment handling sensitive information, and to the precautions taken to limit these emissions.

• The origins of the TEMPEST phenomenon can be traced back to 1943, in a Bell Telephone Company laboratory, by an engineer working on a Bell 131-B2 cipher (i.e. a piece of equipment whose purpose is to "transform" sensitive information received at the input of the cipher into unintelligible information at the output of the cipher, unintelligible at least to...