Matthias Enzmann Marc Fischlin Markus Schneider 0002 A Privacy-Friendly Loyalty System Based on Discrete Logarithms over Elliptic Curves. 24-38 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=3110&spage=24 2004 conf/fc/2004 Financial Cryptography db/conf/fc/fc2004.html#EnzmannFS04