During the radio‐frequency identification authentication process, it is of great significance to quickly find out the target tag from all tags stored in the database, because it affects the authentication performance to a great extent. Most of the existing schemes use the Hash or pseudorandom number generator operation to locate the target tag, but if the number of tags is extremely large, vast Hash or pseudorandom number generator operations may take much time and lower the authentication efficiency. To locate the target tag quickly, the RAP and LADP protocols adopt the simple value comparison method, and the back‐end server can easily find the target tag by directly comparing the received index‐pseudonym value with those stored in the database. This method does improve the authentication performance, but it results that these schemes suffer from the tag tracking attack. Motivated by these concerns, we propose a novel tag indexing method called the two‐layer tag indexing mechanism, and at the same time, we give a lightweight radio‐frequency identification authentication protocol based on it. Analyses show that our scheme can effectively resist the tag tracking attack and is almost as efficient as the RAP and LADP protocols in indexing tags. Copyright © 2013 John Wiley & Sons, Ltd.