Andrei Serjantov Peter Sewell Passive Attack Analysis for Connection-Based Anonymity Systems. 116-131 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=2808&spage=116 2003 conf/esorics/2003 ESORICS db/conf/esorics/esorics2003.html#SerjantovS03