Abstract:

This security problem based on information leakage caused by electromagnetic coupling of metal cables nearby information technology equipment is mentioned.The fundamental electromagnetic compromising emanation models based on network terminal and coupling signal are set up. Three kinds of cable electromagnetic coupling emission model experiment based on QQ instant messaging, mobile and fixed telephone communication are proposed. Coupling leakage signal cann’t be eliminated by communication relay and can be transmitted to the range of communication systems under the condition of a communication system A/D sampling rate to satisfy the Nyquist sampling theorem and the coupling signal not lost by system coding. It is proved by experiments on RS-232 that available data can be reproduced from metal cables nearby information equipment. The highest leakage signal rate and the increasing signal rate methods of the experimental models are discussed. It is proved that the distortionless leakage signal transmission rate is related to A/D sampling and coding system and limited. In addition,the information leakage Approaches based on power line carrier communication, leakage communication and “Soft - TEMPEST virus” are discussed and a actual Coupling Emanation case is given. Finally, these methods of reducing electromagnetic information leakage are discussed. It is hoped that the results play an important role in electromagnetic coupling emanation and better prevent information leakage.

Key words: red signal recognition, electromagnetic compromising emanation, modulation technology, coupling, eavesdropping