R.I. Shabanov – Head of Laboratory,
PJSC «Radiofizika» (Moscow)
E-mail: shabanov.r@radiofizika.com
N.I. Dubovik – Post-graduate Student, Engineer,
PJSC «Radiofizika» (Moscow)
E-mail: dubovik.n@radiofizika.com
V.V. Denisenko – Ph.D.(Phys.-Math.), Head of Department,
PJSC «Radiofizika» (Moscow)
E-mail: dubovik.n@radiofizika.com
The paper discusses theoretical and practical ways of minimizing side electromagnetic radiation and interference (TEMPEST) level of personal electronic computers (PC) and other technical means neither changing their internal structure, nor using expensive and unfavorable for personnel shielded rooms. Operation of any electronic device, including PC, associates with electromagnetic fields existence in the same environment. Based on information security theory TEMPEST generated by electromagnetic radiation housings and cables is one of the possible channels for information leakage.
In the information security theory of PC, compromising emanation (TEMPEST) is a possible channel of information leakage. It is created by electromagnetic radiation of enclosures and system cables. In many cases information system protection methods based on the electromagnetic nature of phenomena coincide with the methods of electromagnetic compatibility (EMC). Therefore, a reasonable solution to these information protection problems is to reduce the TEMPEST level of the system. This article discusses the theoretical and practical ways to minimize the compromising emanation (TEMPEST) of PC without changing their internal structure or applying costly, adverse anechoic chambers. Based on experimental results, principles described in the article confirmed the significant decrease of TEMPEST.
In many cases, the methods of information protection that are based on electromagnetic nature of phenomena, coincide with methods of electromagnetic compatibility (EMC) of technical means. Therefore, a reasonable approach to solve current information security problem, as well as to ensure the EMC of the vehicle, is to reduce the level of the TEMPEST system. Regarding the statement, theoretical prerequisites for protection of the overall system are considered as well as protection from radiation cables and enclosures, namely the following ways to minimize the TEMPEST system level, provided that its structure and transmission lines of useful signals: using equipotential grounding and rational placement of system elements on it; introduction of current and charge circuits to protect elements of the system from radiation and to ensure their resonance with low q-factor at clock frequencies and the system information signals harmonics; system quality factor reduction by increasing losses in the system, achieved by partial aperiodic filling of the system elements area with composite material with given conductive, dielectric and magnetic properties; connection of equipotential grounding plane of the system with protective grounding, given certain requirements of protective grounding.
The experiment was conducted with a usage of personal computer (PC) consisted of a computer system unit, a monitor, a computer mouse, a keyboard and connecting cables. The PC was firstly located on a dielectric table, and then on a table with equipotential surface. The data obtained were compared with control data (without any protection). The system radiation field measurement was carried out with horizontal polarization and in two ranges: from 30 MHz to 300 MHz and from 300 MHz to 1 GHz. Theoretical and practical data obtained as a result of the experiment provide practical recommendations for protection of specific PC information by significantly reducing the TEMPEST level without usage of expensive shielded rooms.
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