With the advancement of technology, the access control system has gradually developed from the original guards and keys to the current non-contact card-type access control management system. The contactless smart card access control management system is more advanced than other access control products, with stable technology, stable performance, good performance and price ratio, and can be widely used in various industries. In the increasingly widespread use of IC cards, IC card access control systems have gradually replaced other existing types of door locks with their access control management, which is safe, reliable, efficient, flexible and convenient, and has become the mainstream way of access control systems.
1 Introduction to the access control system
Access control, also known as access control system. It is a digital management system for managers to enter and exit. With the arrival of intelligent and digital information society, “cards†have gradually penetrated into all aspects of people's lives, people are adapting to cards step by step, and gradually can not be separated from the card. It is no exaggeration to say that mankind will move towards a "card" world. Card is an important means to achieve intelligent management and automated management.
In places where it is necessary to control the access of personnel, such as laboratories with staged mobility, guest rooms, special security departments, etc. If you use a card to open the door instead of the traditional pass and key, you can make management work. Automate and intelligent. Not only users are convenient, but managers are also convenient, and work efficiency and security can be greatly improved. The environmentally friendly IC card access control system described below is a safe and reliable electronic door lock system. With this system, it is convenient to manage and control the entry and exit of personnel in the application place, and to verify the identity and access rights of the entry and exit personnel.
2 Wireless communication (inductive) IC card access control system works
Inductive technology, or radio frequency identification (RFID) technology, is a method of reading information on a card without direct contact between the card and the card reader. With the inductive card reader, the card and card reading device will no longer wear out due to contact friction. There is no need to insert the card into the hole or swipe the card in the magnetic slot. The card only needs to be shaken within the card reader's card reading range. Just fine.
In inductive technology applications, the reader continuously emits a 125 kHz electromagnetic field through its internal coil, which is called the "excitation signal." When a proximity card is placed within the card reader's card reading range, the coil inside the card generates a weak current under the "excitation signal", acting as a power source for a small integrated circuit in the card, and the integrated circuit in the card The storage has a unique digital identification number (ID) entered during manufacture that is transmitted from the card to the card reader via a 62.5 kHz modulation signal, which is referred to as the "received signal." The card reader transmits the received wireless signal back to the controller, which is processed, error-detected and converted into a digital signal by the controller, and the controller then sends the digital identification number (ID) to the microprocessor on the controller. It makes a pass decision.
3 wireless communication IC card access control encryption
The RF IC card is not mechanically contacted with the card reader, so the RF IC card is especially suitable for access control systems with large flow rates. The radio frequency IC card communicates with the card reader by radio communication technology, and the radio wave is open in space and easily intercepted by the outside. Therefore, the logic-free radio frequency IC card without the CPU can not resist the simplest password attack. The communication content is easily stolen, falsified and faked, etc., and its security is not even as good as that of a conventional logic-encrypted contact IC card.
3.1 DES algorithm encryption technology
The DES algorithm encryption technology selects the symmetric cryptosystem. The encryption/decryption keys of most symmetric algorithms are the same, the program design is simple and reliable, the resource overhead is smaller than the convention password, and the operation speed is high. The downside is the heavy workload of key distribution, exchange, and management. The pseudo-random sequence generator in the management server generates a key of 56 bits long. The weak key and the semi-weak key are automatically culled. All the cards and card readers in the whole system are equipped with the product serial number, and the management server automatically assigns each product serial number with a corresponding key to make the key table ready for use and complete the key distribution. The block cipher algorithm in the symmetric cryptosystem is often used on the IC card. Although the DES algorithm is old, it is very convenient to implement in assembly language. Therefore, many systems with less security requirements are preferred.
The DES algorithm is used without any patent or license restrictions. DES algorithm encryption and decryption can be used in the same program, as long as a small change is added at the end of the iteration, so programming is simple and convenient. Strengthened the implementation of correctness. If both the authentication and the authenticated party do not correctly execute the agreement, the agreement will terminate. Each time the data is sent, random numbers are programmed. When the same data is sent, the ciphertext transmitted will not be repeated each time. Resistance to replay attacks has a good effect. Choosing a good pseudo-random number generation algorithm can further improve security.
The biggest weakness of the DES algorithm is that the key length is too short, and it is out of service. It is gradually unable to resist the exhaustive search attack. If the triple DES algorithm is used, this problem can be solved to some extent. The complete 16-round DES algorithm has strong resistance to differential analysis and is relatively weak against linear analysis. There may be some unpublished analysis methods that pose a threat to the DES algorithm, but it is costly to decipher the DES algorithm encrypted message.
3.2 National Password Office Password Algorithm
The non-contact chip card that supports the national cipher board cipher algorithm is popular around the world, and the popularity of various industries is unpredictable. Although chip manufacturers have introduced upgraded chips, they have not been accepted by most markets due to factors such as price and technology popularity. In order to ensure the healthy and orderly development of China's smart card market, under the support and organization of the National Cryptographic Administration, the cryptographic algorithm has also been highly praised and followed by many integrated circuit chip manufacturers in China, and successfully launched related products.
The process of issuing a national secret card can be roughly divided into three steps: card structure establishment; key writing; personalization processing. The card structure should be planned in a unified manner, including the main file, key file, public information basic information file, personal basic information file, application file, record file, directory file, and so on. The key writing includes the card issuing unit master key, the special application subkey, the administrative key, and the like. The initialization card after the key issuing center is centrally written is distributed to each card issuing unit. The card issuing unit carries out the personal basic information file and application file of the unit according to the master key of the card issuing unit, and prints photos, names, etc. on the surface, so that the card for personalization can be sent to the card holder. Finally, the non-contact IC card access control system using the national secret algorithm has successfully used the new and modified access control card system with the relevant ministries.
Conclusion
In short, the working mode, system size, security, reliability, system cost and other factors of the RF smart IC card access control system are often contradictory. It is unrealistic to use a so-called standard system model to meet all the requirements in practice. Only by weighing the pros and cons and selecting the solution according to the specific situation can we design a practical system.
With the development of proximity card technology and biometric technology, IC card intelligent access control and network management system is the integration of technologies such as intelligent micro-system, database, network communication, etc. It enables operators in different locations to implement personnel through the network. , item management, and achieve remote monitoring and alarm.
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