The biggest challenge for current RFID technology is to provide the necessary benefits while avoiding any threats to the privacy of its users. Although many solutions to this problem have been proposed, almost as soon as they have been introduced, methods have been found to circumvent system security and make the user vulnerable. We are proposing an advanced mutual-authentication protocol between a tag and the back-end database server for a RFID system to ensure system security integrity. The three main areas of security violations in RFID systems are forgery of the tags, unwanted tracking of the tags, and unauthorized access to a tag’s memory. Our proposed system protects against these three areas of security violations. Our protocol provides reader authentication to a tag, exhibits forgery resistance against a simple copy, and prevents the counterfeiting of RFID tags. Our advanced mutual-authentication protocol uses an AES algorithm as its cryptograph primitive. Since our AES algorithm has a relatively low cost, is fast, and only requires simple hardware, our proposed approach is feasible for use in RFID systems. In addition, the relatively low computational cost of our proposed algorithm compared to those currently used to implement similar levels of system security makes our proposed system especially suitable for RFID systems that have a large number of tags.