Broken keys to the kingdom: Security and privacy aspects of RFID-based   car keys
  This paper presents an overview of the current state-of-the-art of security and privacy concerns regarding RFID-based car key applications. We will first present a general overview of the technology and its evolution before moving on to an overview and discussion of the various known security weaknesses and attacks against such systems and the associated privacy risks they introduce. 
Jos Wetzels
cs.CR