Knowledge points involved
What is electromagnetic leakage, channels for electromagnetic leakage, how to protect against electromagnetic leakage, and protection standards for electromagnetic leakage. In-depth understanding of electromagnetic leakage protection methods.
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foreword
This knowledge point may be a bit unpopular, but it is no stranger to network professionals, and it is more familiar to security professionals who have become popular in the past few years. Today, I also accidentally saw this word, and then I went to find some information to explain to you. For a moment, I hope you can have an understanding and form this concept in your mind.
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1. Leakage channels
In order to ensure the physical security of the information network system, in addition to the requirements for network planning, site, and environment, it is also necessary to prevent the spread of system information in space. There have been many cases where computer systems have intercepted and lost information through electromagnetic radiation, and the verification work supported by theory and technology has also confirmed that the restoration of this interception distance at hundreds or even kilometers shows the confidentiality of information in computer systems. The work has brought great harm. In order to prevent the information in the system from spreading in space, it is usually necessary to take certain protective measures physically to reduce or interfere with the space signals that spread out. This will become the first condition for important policies, military and financial institutions when building information centers.
The computer mainframe and its auxiliary electronic equipment, such as video display terminals, printers, etc., will inevitably produce electromagnetic wave radiation when they are working, and these radiations carry the data information that the computer is processing. Especially the display, because the displayed information is read by people without any security measures, so the radiation it produces is the most likely to cause leakage. Use special receiving equipment to receive these electromagnetic radiation, and after processing, the original information can be restored.
The application of computers in foreign countries is relatively early, and the radiation problem of computer equipment has already been studied. At the 1967 Computer Annual Conference, American scientist Dr. Weil published a paper explaining the vulnerability of computer systems, summarizing the vulnerability of computers in four aspects, That is: radiation from processors; radiation from communication lines; radiation from switching devices; radiation from output devices. This was the first published paper on computer radiation safety, but it was not noticed at the time. In 1983, a Swedish scientist published a pamphlet called The Leaky Computer, which again addressed the problem of radiation leakage from computers.
In 1985, Dutch scholar Ike publicly published his research report on electromagnetic radiation displayed by computer video at the 3rd Computer Communication Security Protection Conference. At the same time, he used a black and white TV to receive computer radiation leakage signals at the scene. His report sparked an international backlash, and the issue has since been taken seriously. According to relevant reports, foreign countries have developed equipment that can receive and restore computer electromagnetic radiation information within a distance of one kilometer. This method of information leakage enables hostile parties to obtain intelligence in a timely, accurate, extensive, continuous and covert manner. The problem of computer electromagnetic radiation leaks has attracted great attention from all countries in the world. To prevent these information from spreading in the air, special technical measures must be taken to protect and suppress electromagnetic radiation leaks. The technical measures in this area mainly include: interference technology, shielding technology and Tempest technology.
2. Anti-expansion means
1) Configure the video information protection machine (jammer)
Video protection (jamming) technology can be divided into white noise jamming technology and related jamming technology. The principle of white noise jamming technology is to use white noise jammers to emit white noise stronger than computer electromagnetic radiation signals, to cover up electromagnetic radiation signals, and to hinder and interfere with reception. This method has a certain effect, but because it depends on the cover method to interfere, the transmitted power must be strong enough, and too strong white noise power will cause electromagnetic wave pollution in the space; in addition, white noise interference is also easy to be detected by the receiver. Use simpler methods to filter or suppress demodulated reception; Therefore, there are certain limitations and weaknesses in the use of white noise interference technology.
Correlation jamming technique is a more effective and feasible jamming technique than white noise jamming technique. The principle of related jamming technology is to use related jammers to send out related jamming signals that can automatically track electromagnetic radiation signals of computers, so that electromagnetic radiation signals are disturbed and have the effect of data encryption, so that even if the receiver receives electromagnetic radiation signals to interfere, Therefore, its transmission power does not need to be very strong, so the electromagnetic pollution to the environment is also very small. The relevant jammer is simple to use, small in size, affordable in price and remarkable in effect, and is most suitable for use on a personal computer working alone. my country is now able to produce such related jammers.
2) Build an electromagnetic shielding room
The principle of shielding technology is to use a metal mesh or metal plate with good conductivity to form a shielding room or cage with 6 sides, which surrounds the computer equipment that generates electromagnetic radiation and is well grounded to suppress and block electromagnetic waves from propagating in the air. A well-designed and installed shielding room has a better shielding effect on electromagnetic radiation, which can reach more than 60~90dB. For example, the high-performance shielding room developed in the United States has a shielding effect of up to 140dB for the electric field, 120dB for the microwave field, and 100dB for the magnetic field.
The problem that hinders the widespread application of shielding technology is that the design, installation and construction requirements of the shielding room are quite high, and the cost is very expensive. Generally, the cost of a shielding room on a site of 20 to 30 square meters needs tens to millions of yuan. Therefore, the shielding technology is more suitable for some occasions where a high level of confidentiality is required and more important large-scale computer equipment or multiple small computers are placed together, such as national defense military computing centers, large military command posts, and computing centers of intelligence agencies.
3) Configure low-radiation equipment
Tempest technology is low radiation technology. This technology means that when designing and producing computer equipment, anti-radiation measures have been taken for components, integrated circuits, connecting wires, displays, etc. that may generate electromagnetic radiation, to minimize electromagnetic radiation. The production and use of low-radiation computer equipment is a relatively fundamental protective measure to prevent computer electromagnetic radiation from leaking. Tempest is a set of confidentiality standards formulated by the United States. Some advanced industrial countries abroad attach great importance to the application of Tempest technology. Computer equipment used in important occasions has extremely strict radiation requirements. If the U.S. Army replaces all computers with low-radiation computers before going to the front lines of the Gulf War. Abroad has been able to produce serialized Tempest products, such as Tempest personal computers, workstations, connectors, printers, plotters, communication terminals, video displays and so on. The cost of Tempest products is very high, and a Tempest device is 3~4 times more expensive than a device with the same performance.
3. Technical standards
At present, the national secrecy department has formulated "Telephone Electromagnetic Sink Leakage Emission Limits and Test Methods" (BMB-1), Information Equipment Electromagnetic Leakage Emission Limits (GBB-1), "Electromagnetic Leakage of Information Equipment on the Use Site Emission Inspection Test Methods and Safety Criteria" (BMB-2), "Technical Requirements and Test Methods for Electromagnetic Shielding Rooms Handling Confidential Information" (BMB-3) For technical testing of confidential information equipment, the security department can conduct testing through testing instruments. If problems are found, necessary measures are taken in time to plug the loopholes and prevent the leakage of state secrets.
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The above is what I want to talk about today. This article mainly introduces what is electromagnetic leaking and the practical application of electromagnetic leaking technology. I also look forward to sharing more with you. Handsome guys and beauties give a thumbs up. Let’s work together in 2023! ! !