Intrusion Detection and Shielding Measurements using Signals of Opportunity

Shielding effectiveness measurements of big structures such as information security centers, safe rooms, and nuclear power plants can be challenging because they can be time-consuming, costly, and difficult to apply. Since the shielding effectiveness is a critical parameter for such structures, the measurements are needed to be repeated periodically, especially for TEMPEST shielded rooms. This study proposes an improvement to shielding effectiveness measurements utilizing signals of opportunity. In this technique, different from the classical measurement methods, the strengths of already-existing-signals in the given environment are used instead of purposely generating them with dedicated hardware. By taking the differences between the measurements performed inside and outside a cabinet, or a room, a quick estimation can be made for the shielding effectiveness. The technique can be applied to evaluate the deterioration of shielding or as a watchdog for intrusion detection. The paper concluded with a discussion of the pros and cons of the method.