Radio Frequency Identification (RFID) is a technology that incorporates the use of electromagnetic or electrostatic coupling in the radio frequency (RF) portion of the electromagnetic spectrum to uniquely identify an object, animal, or person. RFID Systems technically consist of RFID Tag, Readers, Communication Protocols, Information Systems, Networks Lookup and Location Services. There are several Security threats affect RFID systems; one of them is called de-synchronization attacks. These attacks are aimed to change the values stored in the RFID tags to be not equals to that stored in the database so that tags will not be able to identify valid readers and consider them as attacker. Based on that, researchers have proposed various security and protocols solutions as introduced by Chien. Chien [7] proposed a new ultra lightweight protocol, called SASI, which provides mutual authentication, tag anonymity, data integrity, and forward security. It was designed to resist de-synchronization attack, replay attack, and man-in- the middle attack. However, two de-synchronization attacks were found to break the protocol. In this paper, we propose a new methodology used to prevent vulnerabilities or attacks on SASI. The proposed methodology is considered as a multi level identification schema to prevent active attackers from de-synchronizing the data sent between tags and readers.