What is the encryption principle of IC card in access control system? Seek an answer

Brief introduction of access control system

Access control, also known as access control system. It is a digital management system for managers to go in and out. With the advent of intelligent and digital information society, "card" has gradually penetrated into all aspects of people's lives. People get used to cards step by step, and they can't live without them gradually. It is no exaggeration to say that mankind will move towards the world of "cards". All-in-one card is an important means to realize intelligent management and automatic management.

In places where people need to be controlled, such as laboratories, hotel rooms, secret departments with special needs, etc. If you use the card to open the door instead of the traditional pass and key, you can realize the automation and intelligence of management. It is not only convenient for users, but also convenient for managers, and the work efficiency and safety can be greatly improved. The environmental protection IC card access control system introduced below is a safe and reliable electronic door lock system. Using this system, it is convenient to manage and control the access of application site personnel, and verify the identity and access rights of personnel. Working principle of wireless communication (induction) IC card access control system

Induction technology or radio frequency identification (RFID) technology is a method to read the information on the card without direct contact between the card and the reader. With the inductive card reader, the card and card reading equipment will no longer be worn due to contact friction, and it is no longer necessary to insert the card into the hole or swipe the card in the magnetic slot. The card only needs to shake within the reading range of the card reader.

In the application of induction technology, the reader constantly sends out 125kHz electromagnetic field through its internal coil, which is called "excitation signal". When the induction card is placed in the reading range of the card reader, the coil in the card generates a weak current under the induction of the "excitation signal", which is used as the power supply for the small integrated circuit in the card. The integrated circuit in the card stores the unique digital identification number (ID) input during manufacturing, and transmits it back to the card reader from the card through a modulation signal of 62.5kHz, which is called "received signal". The card reader sends the received wireless signal back to the controller, which processes, detects and converts it into a digital signal, and then the controller sends this digital identification number (ID) to the microprocessor on the controller, and the microprocessor makes a flow decision.

3 wireless communication IC card access control encryption

There is no mechanical contact between RF IC card and card reader, which is especially suitable for large-flow access control system. Radio communication technology is used to communicate between RF IC card and card reader. Radio waves are open in space and easy to be intercepted by the outside world. Therefore, the ordinary logic encryption RF ic card without CPU cannot resist the simplest password attack, and the communication content is easy to be stolen, tampered with and forged, and its security is even worse than that of the ordinary logic encryption contact IC card.

DES algorithm encryption technology

DES algorithm encryption technology chooses symmetric cryptosystem. Most symmetric algorithms have the same encryption/decryption key, and the program design is simple and reliable, with low resource overhead and high operation speed. The disadvantage is the heavy workload of key distribution, exchange and management. The pseudo-random sequence generator in the management server generates a key with a length of 56 bits. Weak keys and semi-weak keys are automatically eliminated. All cards and card readers in the whole system are programmed with product serial numbers, and the management server automatically assigns different keys to each product serial number, making a key table for use and completing key distribution. The block cipher algorithm in symmetric cryptosystem is often used on ic cards. DES algorithm is relatively old, but it is easy to implement in assembly language, so many systems with low security requirements still give priority to it.

There are no patent and license restrictions for using DES algorithm. DES algorithm encryption and decryption can use the same program, as long as a small change is added at the end of iteration, so programming is convenient and simple. Strengthen the correct execution. If one of the authenticators and the authenticated party fail to execute the agreement correctly, the agreement will be terminated. Every time data is sent, it is encoded with random numbers. When sending the same data, the transmitted ciphertext will not be repeated every time. Resisting replay attacks has a good effect. The selected pseudo-random number generation algorithm can further improve the security.

The biggest weakness of DES algorithm is that the key length is too short, and it has become invalid, and it is gradually unable to resist exhaustive search attacks. If the triple DES algorithm is adopted, this problem can be solved to some extent. The complete 16 DES algorithm has strong anti-differential analysis ability and relatively weak anti-linear analysis ability. There may be some unpublished analysis methods that pose a threat to DES algorithm, but it takes a certain price to decipher the messages encrypted by DES algorithm.

Cryptography Algorithm of National Cryptography Bureau

Contactless chip cards supporting the encryption algorithm of the National Cryptography Bureau are popular all over the world, and the popularity of all walks of life is unexpected by chip manufacturers. Although chip manufacturers have introduced upgraded chips, they have not been accepted by most markets due to factors such as price and technology popularization. In order to ensure the healthy and orderly development of China's smart card market, with the support and organization of the State Cryptography Administration, this cryptographic algorithm has also been respected and imitated by many domestic IC chip manufacturers, and related products have been successfully launched.

The process of issuing country secret cards can be roughly divided into three steps: establishing card structure; Focus on writing; Personalized processing. The card structure should be planned in a unified way, including main files, key files, public basic information files, personal basic information files, application files, record files and directory files. Key writing includes the master key of the card issuing unit, special application sub-key, management key, etc. The initialization card compiled by the key card issuing center is distributed to all card issuing units. According to the master key of the card issuing unit, the card issuing unit loads its personal basic information file and application file, and prints photos, names, etc. On the surface, it can issue personalized cards to cardholders. Finally, the non-contact IC card access control system using national security algorithm has been successfully applied to the access control system newly built and reconstructed by relevant ministries.