As radio-frequency identification (RFID) can quickly identify an object without requiring physical contact, it provides efficient identification for the verification of individual objects. There are currently numerous practical applications for RFID systems in various domains. For example, RFID mechanisms can be used to check whether large quantities of goods are present within a supply-chain system. Similarly, information about a product can be acquired in a supermarket without asking the clerks for help. The aforementioned applications are limited with regard to authentication between a single tag and a server, but other applications focus on authenticating the relationships among the tags. For example: a passenger carries a package while boarding an airplane. An airline agent has to check whether or not the package and the boarding card are correct and if the package corresponds to the boarding card. In this paper, we use a yoking-proof mechanism conforming to EPCglobal Class 1 Generation 2 standards to solve this double problem. In addition, the proposed scheme can provide a convenient, low-cost, and improved security mechanism for identifying the simultaneous presence of tags. Copyright © 2011 John Wiley & Sons, Ltd.