Research On Electromagnetic Information Leakage

Compromising emanations of information technology equipments (ITE's) may cause security risk of information being processed on them. Electromagnetic information leakage, which turned to be a domain of inforwar, has attracted worldwide attention. This topic is studied in this dissertation by means of time-domain electromagnetics.The research can be classified into three parts here. Firstly time-domain radiation mechanism of emanation sources is studied. In Chapter 2, two kinds of physical models, traveling wave monopole model and standing wave dipole model, are set up as well as information theory models. In Chapter 3, electromagnetic radiation of electron beam in cathode ray tube (CRT) of computer video display unit (VDU) is analyzed as a special example.Secondly some protection measures on electromagnetic information leakage are put forward. In Chapter 4, method of moment (MoM) solution of transient electromagnetic scattering by perfect conducting surfaces is discussed by dealing with time-domain integral equations (TDIE's). Rectangular patches model and triangular patches model are compared and their applications are exploited. In the mean time reference [42] and [61] are recruited. In Chapter 5, the author's work is focused on shielding enclosure design of computer VDU. Enough consideration is made on air-flow for heat dissipation.Thirdly interception technology of electromagnetic information leakage is described. In Chapter 6 a digital interception system is designed and its operating principle is introduced. Plenty of experimental results are provided here. In Chapter 7 a mathematic model of electron beams in CRT of computer VDU is given and entropy preservation performance of TEMPEST transceiving system is discussed, a soft-TEMPEST measure is suggested accordingly. Subsequently anti-noise performance of the digital interception system is analyzed. In other chapters, e.g. Chapter 1, research progress of electromagnetic information leakage technology is reviewed, and in Chapter 8 the whole dissertation is concluded and some prospective research topics are suggested.A number of innovative results in the dissertation are outlined as followings,1. Time-domain radiation models are brought forward for compromisingemanation by applying standing wave dipole model and traveling wave monopole model to problem of electromagnetic information leakage.2. The modified traveling wave monopole model is employed in simulating the electron beam in CRT of computer VDU. Meanwhile acceleration fields of the electron beam are studied in details and its expression given for the first time with measured results. A novel analyzing method is proposed to study the spectrum of electromagnetic information leakage based on the viewpoint of field point, which has been verified effective by experiments.3 . Shielding schemes of computer VDU are suggested through transient electromagnetic scattering analysis. Method of time-domain integral equations is used here. A new Soft-TEMPEST method is found to strengthen protection capability of electromagnetic information leakage.4. A novel digital interception system is assembled and employed in eavesdropping on computer VDU successfully.5 . Information theory models are established of emanation sources and interception system. Entropy preservation is considered of the TEMPEST transceiving system. Anti-noise performance of the digital interception is also taken into account by both theory and experimentElectromagnetic information leakage and its protection & interception technology are studied theoretically and experimentally in this dissertation. The author tried his best to solve the problem in detail and expects to lay a solid foundation for further research.