2.8 Electromagnetic compatibility and electromagnetic information radiation
2.8.1 Electromagnetic compatible EMC
Device or system of electromagnetic compatibility (Electromagnetic Compatibility) according to national standard GB / T4365
Unfold that the device or system can work normally in its electromagnetic environment and does not constitute an electromagnetic that cannot be affected by anything in the environment.
Interference capabilities (so-called electromagnetic environments refer to all electromagnetic phenomena of the given place, including the sum of all times and full spectrum
). When the device or system can reach this, it can be referred to as electromagnetic compatibility. From the above description, you can see if
If the equipment or system is to achieve electromagnetic compatibility, it must be two points:
1. Work normally in the electromagnetic environment, which is to resist or prevent external electromagnetic interference;
2. Electromagnetic interference that cannot be affected by anything in the environment, which is to suppress the electricity of the equipment or system itself.
Magnetic interference does not affect other equipment or systems.
With the development of technology, especially the enhancement of people's environmental protection, the electromagnetic compatibility of products is increasingly attached
. my country has incorporated the electromagnetic compatibility requirements of the product in the scope of national mandatory product certification, and the state regulations from May 2003.
On the 1st, the products listed in the National Compulsory Product Certification Directory will not be able to find factory, imports and sales.
Electromagnetic compatibility is the same as those we are familiar with, is one of the most important indicators of product quality. Security involves
Personal and property, and electromagnetic compatibility involves personal and environmental protection. There is indeed another in the space of our daily life.
An external environmental pollution - electromagnetic pollution. It can be said that the equipment that is electricity, and switch can generate electromagnetic interference.
Since the establishment of the National Radio Interference Standardization Committee since 1986, my country has begun to organize and systematically correspond
CISPR / IEC launches domestic EMC standardization. At present, my country has developed more than 60 EMC national standards, of which the basic standard
Specification for the radio interference and immunity measurement equipment for GB4365-1995; GB / T6113-1995.
2.8.2 Transient electromagnetic pulse radiation standard Tempest
Electromagnetic compatibility standards in computer systems are mainly transient electromagnetic pulse radiation standards Tempest (Transient Elec)
Tromagnetic Pulse Emanation Standard. The development of this technology has been 40 years of history, it is electricity
A new research direction developed by the magnetic compatibility (EMC) field. The specific content of the Tempest program is for information
Electromagnetic radiation and information leakage problem, a series of research and research from the two aspects of information reception and protection
Make information reception, deciphering level, leakage ability and technology, relevant specifications standards and management methods.
Tempest is a secret professional term from the United States. Its research object is information about processing sensitive information equipment and systems.
Leakage problem is an important part of information security. Tempest mainly threatens the confidentiality of information, preventing very sleepy
Difficult, the consequences may be very serious. Electronic intelligence acquisition is divided into invading and non-intrusive, and intrusive systems often refer to sensitive.
Regionally intentionally install the stealing apparatus to obtain information; rather than invading systems utilize leakage signals receiving air in an inactive area
Get information, this way is dangerous, it is not easy to be discovered and perceived, where the reception of TempeSt leakage is non-invasive
An important means of intelligence acquisition. The United States has decided to decrypt some Tempest standards before the early 1990s.
This is not a signal that the United States believes that Tempest is not important. On the contrary, it is very likely that the United States has developed Tempest technology.
Enter a new stage sign.
Since the computer system is the most critical and important components in various information processing devices, it is also useful.
Electromagnetic emission of the device acquires information intelligence more timely, accurate, extensive, continuous, safe, reliable, and concealed. positive
For this reason, Tempest protective research is generally for computer systems and their peripheral configuration. Tempe
ST's research object also includes receiving systems, electrical passes, digital phones, etc.
The electromagnetic radiation of the information processing device has two aspects: 1) constitute pollution to the electromagnetic environment; 2) Confidentiality and information confidentiality will constitute a serious threat.
Any electronic device or line that generates electromagnetic waves if there is a time-change current signal, and the launch intensity is strong.
Degree and change rates are proportional. The transmitted signal is propagated along a free space or a conductor that is in contact or proximate the emitting source. Such as
If the current change current signal is related to the confidential information, it is called red signal, which causes the current signal signal.
The launch is called a COMUSING EMANATION, the transmitted signal is like broadcast, the TV signal is the same,
It can be received remotely and can be reconstructed, and the contents of the confidential information can be reconstructed. Has been analyzed: for the digital circuit group
Since the information processing equipment, the radiation spectrum and harmonics are very rich, it is easy to steal and interpret them.
The problem of interest leakage is more prominent and severe, as an example of computer video displays, all of which are printed circuit boards, each component
Power supply. Signal interfaces, data cable, drive circuit, cathode shot tube, etc.
Different electromagnetic radiation. In the radiation spectrum, the included information is also different, including clock / data frequency information, and the like.
In theory, this information can be received and interpreted, but it is just a difficult degree. Using the electromagnetic emission of information equipment
Get information intelligence is more timely, accurate, wide, continuous, safe, reliable, and concealed.
In 1960, in the joining the European community negotiation, in order to find the French attitude, the British agent Peter Wright notes the law.
The encrypted information on the Kingdom code machine will carry weak auxiliary signals, and radiate in electromagnetic wave, they use equipment
Receive it, using the signal successfully reproduces the express text information, so that the UK fully mastered the state of the French delegation in negotiations.
degree. According to the analysis, this signal is an electromagnetic leakage transmitted by the intermodulation of the red signal of the encryption device on the line.
The electromagnetic leakage launch of the encryption device is critical. This electromagnetic leakage transmits tends to make the construction password algorithm.
The power is banding, and the stealing person will easily get the data you want to get. American scholar Kelsey, Schneier, 1999
Gner and Hall jointly published a papers using indirect information to attack the password algorithm, discussed the use
Indirect information such as information, processor status flags and power, etc. Attack on Idea, RC5, and DES such as password algorithm. They recognize
There are many things in theory of password attacks. It is actually a poor operability. It is often called a vulnerability in theory of password algorithms.
"Certificational Weakness", often not practical in actual attacks. In recent years
Deciphering of the password algorithm, Timing Attacks and Differential Power Analysis (Differential P)
Ower analyysis, this type of method makes full use of indirect information leaked by encryption equipment (such as timing information and power consumption)
Information) Deciphering, they classify such methods in the side channel password analysis (Side-Channel Cryptanalysis
). Use side channel password analysis to decipher the password algorithm for intelligence department is a powerful tool, the British agent is
Deciphering French password based on side channel information.
2.8.3 Tempest's protection method
Protection of leakage is a very complex and meticulous project, with an increase in information leakage channels, protection technology
Continuously expand and in-depth, and involve information on information theory, electromagnetic field, microelectronics, electromechanical processing, and material sectors.
Application. Among them, the protection technology of electromagnetic leakage is simple to divide physically isolated, electromagnetic isolation, and the transmitting level is most
Multi-way methods such as smallization and interference protection.
Physical isolation: Guaranteed that unauthorized personnel are far from the red equipment area, which makes it getting red in the area where the unauthorized person is located.
The leakage transmitted signal is much smaller than the background noise intensity of the area.
Electromagnetic isolation: Unsecured emission of unrecognizable red equipment using shielding, filtering, and other electromagnetic field isolation methods.
Minimization of emission level: The power level of the circuit design and operation should drop to the lowest possible level, reduce unconscious
The intensity of the launch.
Interference protection: economic, effective and simple protection means. Because non-related noise interference is easy to pass the cycle
Both are suppressed, so the interference signal should have correlation with the protected leakage transmit signal, and the good interference can be produced.
The relevant output signal.
In practice, there are often many ways to use, complement each other, and integrated use can achieve the best cost performance. Such as beauty
The TempeSt equipment is divided into different levels of emission levels in the Tempest standard, and each level corresponds to different distances.
Application environment, each case has corresponding recommendations, making full use of physical isolation, electromagnetic isolation and leakage
Three methods of launching level.
2.8.4 Non-official research results of Tempest
Foreign non-official scholars have a strong academic atmosphere studying Tempest technology, and there is constant achievement, to a certain extent
Entered the in-depth and development of Tempest research.
In February 1985, in the 5-minute TV show in the BBC (BBC), 5 minutes of TV shows,
Computer electromagnetic leakage transmitted performance. A van stopped in front of a building in the show,
Gradually transferred to the TV screen on the TV screen in the caravan, the commentator shows that the document comes from the far building
Computer screen. This program shows the Dutch engineer Van Eck to the computer CRT display leakage launch research
Part of the result. A ultra-high frequency three-band antenna (10dB gain) is installed on a 10-meter-tall pole. Antenna
After the received signal is enlarged 18dB, the received signal is displayed on the TV screen in the car. March 1985, Van Eck in Cannes, France
In the 85-year security computer meeting, he introduced his research results and used the modified black and white TV demo to receive calculations.
Machine monitor image. At the meeting, VAN ECK explained that all of his devices had a total cost of $ 225. Van ECK said, use
More complex, expensive devices, can detect data display on the terminal screen at a distance of 1 km. VAN E
CK's thesis and demonstration have caused a huge response, and more than 700 related articles have been published in Europe within a week. According to reports
The Tempest experts in the United States were also very surprised to the research of Van ECK. Because Van ECK's research results are pioneering
Many foreign articles are called "VAN ECK Launch" in abroad.
In 1990, the Dutch Scholar Peter Smulders discussed the original of the electromagnetic leakage launch of the RS232 communication line in a paper.
Treatment and receiving techniques, and introduce experiments using modified FM radio receiving cables. The paper is given
With the experimental results in the environment, the frequency modulated radio can be used away from the RS232 cable (non-shielded lines and shield lines) 7
, 8 meters long local receiving the data transmitted on the line. SMULDERS confirmed the use of line conduction emission acquisition red signals
The possibility.
Tempest technology habits refers to the unintentional leakage and its protection technology of electromagnetic signals, compared with the University of Cambridge in 1998 K
UHN and ANDERSON two scholars introduced the use of electromagnetic leaks to pass hidden data for active attack acquisition calculations.
Technical and prevention methods of machine information, and refer to it is Soft Tempest. In their papers through simple demonstration
Describe the effectiveness and concealment of this hidden approach. From the attack angle, by implant the target computer,
Stealing the data in the hard disk and hide the video information of the target computer in a manner suitable for electromagnetic leakage.
Receive the restored device to receive hidden data. After the publication of the paper, there is a wide concern. There are many people pass experiment, verify
Not only can CRT hide leakage information, but other hardware such as CPU and PCI bus, by programming, the purpose of changing the leakage transmitted information can be achieved on the bus last cycle. This so-called "TempeSt virus" is suitable for
Attacking physically isolated computers, more concealed.
Kuhn, the University of Cambridge, also published a paper that discussed the principle of receiving long-distance CRT display light leakage signals and
Preventive technology, he believes that this light leakage and VAN ECK electromagnetic leaks are similar to the current complex electromagnetic environment.
easy to accomplish. KUHN provides reflection of the wall with a photovoltaic device to receive the display of the wall in the paper and recovery
Experimental results of the screen data. The radiation after the wall reflection will generate diffuse, but after a high pass filter
You can get a relatively clear picture. If you estimate the channel, you can use the matching filter to get quite
Clear results. In the paper, he pointed out that if it is received in a relatively dark environment, the reception distance can be reached.
Dozens of meters to a few hundred meters. Correspondingly, the switch to which the state light indicating the network data is received through a distance to obtain the transmitted data.
Rong, also proven by experiments.
NSUN 2004
