Radio Frequency Identification (RFID) devices have been recently introduced in several applications and services such as National Identification Cards, Passports, Credit Cards, etc. In this paper, we investigate the security of such devices by showing the possibility of con- ducting RFID eavesdropping using simple and common devices such as a Software Defined Radio platform. Generally classical RF attacks can be made on long range transmission protocols, however we extend the standard RF attacks to cover RFID communication protocols. In this manuscript, an off-line step-by-step analysis is developed to prove the feasibility of reversing a complete RFID protocol. A real-time implemen- tation is also realized to highlight a real threat in the everyday life.