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1 The hidden dangers of RFID technology
Tags: RFID tags are easily manipulated by hackers, pickpockets, or grieving employees.
Network: Including competitors or intruders installing illegal readers on the network, and then sending the scanned data to others.
Data: One of the main benefits of RFID is to increase the transparency of the supply chain, but this brings new hidden dangers to data security. Companies must ensure that all data is very secure, not only referring to the security of their own data, but also to the security of related data of their trading partners.
2 RFID security problem solution
(1) Stream password encryption
The encryption process can be used to prevent active and passive attacks, so the plaintext can be encrypted before transmission, so that hidden attackers cannot infer the true content of the information.
The encrypted data transmission is always carried out in the same mode: the transmission data (plain text) is processed by using the key K1 and the encryption algorithm to obtain the cipher text. Any attacker who does not know the encryption algorithm and encryption key K1 cannot crack the ciphertext to obtain the plaintext, that is, cannot reproduce the true content of the transmitted information from the ciphertext. At the receiving end, use the decryption key K2 and the decryption algorithm to restore the ciphertext into plaintext.
According to whether the encryption key K1 and the decryption key K2 used are the same. Encryption systems can be divided into symmetric key systems and public key key systems. For RFID systems, the most commonly used algorithm is to use a symmetric algorithm. If each symbol is individually encrypted before transmission, this method is called a stream cipher (also called a serial cipher). On the contrary, if multiple symbols are divided into a group for encryption, it is called a block cipher. Usually block ciphers are computationally strong, so block ciphers are less used in radio frequency identification systems.
(2) Stream cipher generation
In the data stream cipher, each step uses a different function to transform the character sequence of the plaintext into the encryption algorithm of the cipher sequence. In order to overcome the problem of key generation and distribution, the system should create a stream cipher in accordance with the “one-time insertion” principle. At the same time, the system uses a so-called pseudo-random number sequence to replace the real random sequence, which is generated by a pseudo-random number generator.
The pseudo-random number generator is generated by a state automaton, which is composed of a binary storage unit, a so-called flip-flop. The basic principle of using a pseudo-random generator to generate a stream cipher: Since the encryption function of a stream cipher can be changed randomly with each symbol, this function not only depends on the currently input symbol, but also on additional characteristics, namely its Internal state M. The internal state M changes with the state transition function g(K) after each encryption step. The pseudo-random number generator is composed of components M and g(K). The security of the ciphertext mainly depends on the number of internal states M and the complexity of the state transformation function g(K). The research on stream ciphers is mainly the research on pseudo-random number generators. On the other hand, the encryption function f(K) itself is usually very simple, and may only include addition or “XOR” logic gates.
The pseudo-random number generator is realized by a state automata. It consists of binary storage units (so-called flip-flops). If a state machine has n storage units, it can take 2n different internal states M. The state transition function g(K) can be expressed as combinatorial logic. If limited to the use of linear feedback shift registers (LFSR), the development and implementation of pseudo-random number generators can be greatly simplified. The shift register is composed of flip-flops in series (output n is connected to input n+1), and all clock inputs are connected in parallel. For each clock pulse, the flip-flop moves one bit forward with the clock pulse, and the content of the final flip-flop is the output.
(3) PLL synthesizer part
The PLL synthesizer part adopts AD Company’s ADF4106, which is mainly composed of low-noise digital phase detector, precision charge pump, programmable frequency divider, programmable A and B counters and dual-mode pinning frequency divider. The digital phase detector is used to compare the output phases of the R counter and the N counter, and then output an error voltage proportional to the phase error of the two. There is also a programmable delay unit inside the phase detector to control the width of the flip pulse. This pulse ensures that the phase detector’s transfer function has no dead zone, thus reducing the phase noise and the introduced spurs.
(4) RSA “soft blocker” security scheme
Although many companies have just begun to consider RFID security issues, privacy advocates and legislators have been concerned about label privacy issues for some time. RSA Security demonstrated the RSA “Blocker Tag,” a specially designed RFID tag built into a shopping bag that can launch a DoS attack. Prevent the RFID reader from reading the tags on the purchased goods in the bag. But the disadvantage is: Blocker Tag provides pickpockets with a way to interfere with store security. Therefore, the company changed its approach. The method is to use a “soft blocker”, which strengthens consumer privacy protection, but only executes after the item is actually purchased.
3 concluding remarks
At present, the RFID tag system has been widely used in military, logistics, merchandise retail, industrial manufacturing, animal identification and anti-counterfeiting identification. As the initial RFID application design and development process did not consider the security issues of the security system, security issues were caused. It is becoming more and more severe and has become an important factor restricting the wide application of RFID. Without a reliable information security mechanism, the data information in the radio frequency tag cannot be effectively protected. If the information in the tag is stolen or even maliciously tampered with, it may bring logistics security. At the same time, radio frequency tags that do not have a reliable information security mechanism also have security risks such as easy leakage of security sensitive information to neighboring readers, easy interference, and easy tracking.
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