Ari Juels Ravikanth Pappu Squealing Euros: Privacy Protection in RFID-Enabled Banknotes. 103-121 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=2742&spage=103 2003 conf/fc/2003 Financial Cryptography db/conf/fc/fc2003.html#JuelsP03