De-synchronization Attack on Quadratic Residues-Based RFID Ownership Transfer Radio Frequency Identification (RFID) ownership transfer protocol aims at securely updating RFIDtag’s internal state and key such that only the current owner of a tag is allowed to access the tag when it is transferred from one owner to the next. Doss et al. [32] proposed two very promising RFIDownership transfer protocols which represented state of the art and were claimed to own excellent security performance and computational performance. However, we will show our de-synchronization attack on these protocols.