Researches On The Key Technologies Of UHF RFID Systems

Radio Frequency Identification (RFID) is a non-contact automatic identificationand data acquisition technology that uses radio waves. With the excellent features,such as no line-of-sight requirement, long operating range, working under harshenvironment and so on, RFID is widely used in various information systems.Ultra-high frequency (UHF) RFID has many advantages compared to low-frequencysystem, such as longer read range, faster data rate, programmability, which make ithave important application prospects and far-reaching significance.Widespread adoption of RFID technology is limited by two main issues, the firstof which is collision. In a dense tag environment, when multiple tags replysimultaneously to a reader, tag collision occurs and causes low tag readingperformance and a waste of valuable energy. Another issue needed to be addressed isthe security and privacy of users, which are critical because RFID systemscommunicate via radio waves, subjecting them to unauthorized scanning. In thisthesis, anti-collision algorithms and authentication protocols have been explored andstudied for UHF RFID systems. The main contributions are as follows:First, unlike most existing anti-collision algorithms with little regard ofparameters in RFID applications, a novel anti-collision concept is proposed, byanalyzing and improving Q-Algorithm which is introduced in a standard, EPCglobalClass1Generation2. We maximized the efficiency of tag identification by modifyingand optimizing the parameters used in Q-Algorithm. In addition, to avoid unnecessarytransmission, the reader sends QueryAjust only when Q has been changed.Quantitative analysis and simulation results prove that the proposed Fast Q algorithmcosts less identification time and unnecessary collided slots than that of othersolutions.Second, an enhanced RFID authentication protocol based on Rabin encryptionscheme is presented. In the improved protocol, random numbers are generated both byreaders and tags. In order to save the storage on the tag, the public key is representedby a composite Mersenne number. Moreover, the transmitted information is encryptedby Rabin scheme and Hash function. Analysis demonstrates that the improvedprotocol not only can resist various attacks and ensure privacy, but also needs less computation and storage on the tags and server compared to other related schemes.Third, to deal with the security issue of multi-server RFID systems in practicalapplications, a novel mutual authentication protocol is suggested. In the proposedprotocol, the system assigns an identifier for every server and a key for each of theservers and tags. Moreover, each tag stores all servers’ identifiers and the shared keysbetween itself and every server. When a reader queries a tag, it is firstly identified bythe tag, finding the shared key, and then it has the chance to enter the authenticationstage. Compared with other existing protocols of same class, our protocol can resistvarious attacks and achieve better performance in computational cost.Four, a temporary delegation protocol for RFID system is introduced. Throughexecuting the protocol, a back-end server can delegate the right to identify andauthenticate a tag to a specified entity, such as a reader, to reduce the server’scomputational load and improve scalability. The new protocol is also used to provideauthorization recovery as the previous owner can be viewed as a delegate. In this way,the current owner can allow the previous owner to gain back the access to the RFIDtag without going through instances of the ownership transfer protocol, which makesthe RFID system more efficient in terms of computation and communication.Finally, a RFID authentication scheme that supports secure and efficient tagownership transfer is proposed. The ownership transfer model is built at firstaccording to its security properties. On this basis, three parts of the new scheme arepresented, which are ownership transfer protocol, secret update protocol andauthorization recovery protocol, respectively. In order to preserve both the previousand new owners’ privacy, the proposed protocol allows the previous owner to changethe key first, then send the new key to the new owner via a secure channel, and finally,let the new owner to change the key again. Security analysis shows the new protocolsatisfies the security requirements of ownership transfer. Moreover, the authorizationrecovery is achieved by executing temporary delegation protocol. Compared with thetraditional ways, the proposed one reduces the computation and communicationgreatly and has broad application prospects.These contributions open up new research approaches for anti-collisionalgorithm and authentication protocol of RFID systems. They also provide valuableresearch work and meaningful references for solving related issues in practicalapplications.