Many electronic information processing equipment has strong electromagnetic leakage. When using these devices, various information processed will inevitably be scattered into a certain space. This poses a great threat to the confidentiality of information. Even if cryptographic communication is used, the information content has been radiated into the surrounding space along with electromagnetic waves in the processing before encryption or after decryption. In this way, not only can the information be leaked, but by detecting the plaintext information before encryption and the encrypted password information, it is possible to continuously compare and analyze the plaintext information and the password information. After multiple detections, the password information, even advanced password information can be deciphered, so that the password information loses the meaning of confidentiality.
Therefore, when using electronic computers and other electronic information processing equipment, it is very dangerous to start processing confidential information without taking reliable technical measures.
The correct use of different types of shielded rooms or shielded rooms is a reliable measure to prevent the leakage of information along with electromagnetic waves. The shielded room can not only prevent the confidential information processed by indoor electronic computers and other electronic information processing equipment from leaking out with electromagnetic waves, but also prevent relatively strong external electromagnetic interference from disturbing the normal operation of indoor electronic computers and other electronic information processing equipment.
1. Proposal of Information Leakage Prevention Technology
For a long time, the radiation safety of computers has not attracted enough attention. It is believed that it is very difficult to distinguish and separate the information radiated from the computer from the complex noise background near the computer-screen door.
At the Computer Annual Conference in 1967, American scientist Weir first clarified the four vulnerabilities of computer systems, namely the radiation problems of processors, communication lines, conversion equipment, and output equipment. When a computer is running, electromagnetic radiation signals are not only rich in spectral components but also carry information, which poses a threat to the security of information.
In 1983, Swedish scientists listed several radiation leakage problems of computers: the radiation of video signals, the radiation of radio components and the radiation of power lines-shielding windows.
In 1985, Dutch scholar Ike publicly published his research report on electromagnetic radiation of computer video display units at the third computer communication security protection conference. He successfully used an improved ordinary black and white TV to convert computer video The information displayed on the unit is reproduced and is clearly readable. From then on, people began to take this issue seriously-shielding cabinets.
According to related reports, foreign countries have developed equipment that can receive and restore computer electromagnetic radiation information beyond 1 km. This information leakage method enables adversaries to obtain information in a timely, accurate, extensive, continuous and covert manner. The issue of computer electromagnetic radiation leakage has attracted the attention of various countries. To prevent this information from spreading in the air, protection and restraint must be taken.