Chiara Bodei Pierpaolo Degano Riccardo Focardi Corrado Priami Authentication Primitives for Protocol Specifications. 49-65 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=2763&spage=49 2003 conf/pact/2003 PaCT db/conf/pact/pact2003.html#BodeiDFP03