Research On Key Techniques In Identification And Security For Low-Cost RFID Systems

Radio frequency identification(RFID) can realize the automatic recognition of objects using non-contact way, and has been widely used in identity recognition, payment systems, business supply chains and supermarkets, anti-counterfeiting, integrity test of goods and entrance guard system. The application of RFID technology will bring us a lot of conveniences, there are several urgent key issues need to be addressed in these applications. First, it is the problem to identify multi-tag. When a reader identifies multiple tags, these tags will respond simultaneously to the queries of reader. Since the response signal of tags share a wireless channel, so the response signals of multiple tags will cause a collision. After the collision, the reader needs to query and identification tag again, result to reduce the recognition efficiency, so a RFID system need anweffective way to to avoid the collision. Second, it is the security and privacy problems in RFID system. Because RFID technology uses wireless technology, a wireless transmission is a broadcast way, and it is easily to be exploited by attackers. This requires the use of certain encryption technology to protect RFID systems security and privacy, but on the other hand, low-cost tags have limited computing power, and it can not complete the sophisticated encryption operation. Therefore, when design a security protocols of RFID systems should be balance the relationship between safety and cost of the tags.In radio frequency identification system, the-efficiency that the reader identifies multiple tags is closely related to the methods to solve the collision of multiple tags. At present, a reasonable solution is the introduction of4-ary query tree (or n-ary query tree) to reduce the collision timeslots. The advantage of a4-ary tree anti-collision algorithm is that it is able to reduce collision timeslots, but it also increases the idle timeslots. To reduce these excessive idle timeslots the4-ary tree anti-collision algorithm brings, an anti-collision algorithm based on adaptive4-ary pruning query tree (A4PQT) is proposed in this paper. On the basis of the information of collision bits, some idle timeslots can be eliminated through pruning the4-ary tree. Both theoretical analysis and simulation results support that A4PQT algorithm can significantly reduce recognition time and improve throughput of the RFID system.To deal with the security and privacy problems of Radio-frequency Identification system, the author proposes a trajectory privacy model for RFID system. The model first formalizes Adversary Model and then defines adversary indistinguishability privacy game and interval security privacy game according to the ability of adversary. Based on the privacy game between adversary and challenger, the author gives the definition of weak trajectory privacy and strong trajectory privacy. Last, the thesis analyzes the privacy protection level of present RFID systems with the help of this trajectory privacy model. It can be seen that the trajectory privacy model can effectively analyze and find the privacy vulnerabilities of RFID security protocol.Because of the very wide range of applications of low-cost tags, but low-cost tags have limited computing power, and it can not complete the sophisticated encryption operation. To balance the relationship between safety and cost of the tags. A lightweight RFID authentication protocol with strong trajectory privacy protection (LAP-STP) is proposed. In this protocol, tags only use pseudo-random number generators operation and XOR operation, and it effectively reduces the computational burden of tags. In the process of authentication, the tag has been used pseudonyms to prevent the disclosure of sensitive information, the pseudonyms and the secret number of a tag have been synchronized with the backend server, these measures can effectively prevent the de-synchronization attack, man in the middle attack, forward security, replay attack and cloning attack, but also can meet the requirements of low cost tags. The LAP-STP protocol is also proved that it has a strong trajectory privacy and security by using the trajectory privacy model of RFID system. Compared with the existing relevant research, the LAP-STP protocol has better performance on the memory overhead of tags, computing costs, communication overhead, as well as the search efficiency of backend server. Group proof protocol widely used,during generation of a grouping proof for a large number of tags, the response signals of multiple tags will cause a collision that impacts the efficiency of the grouping proof generation, in order to solve this problem, a scalable lightweight grouping-proof protocol for RFID systems (SLGP) is proposed. In this protocol, tags only use pseudo-random number generators operation and XOR operation. An anti-collision algorithm based on adaptive4-ary pruning query tree is used to identify the response message of tags. The update of the secret number of a tag has been synchronized with the verifier. The SLGP protocol not only solves scalability problem of the low cost tag, but also improves the efficiency and the security of group proofs protocol. Compared with the existing relevant group proofs protocols, the SLGP protocol simply need smaller computational complexity for tags, and it achieves an effective balance between the security and the usability.