Steven J. Murdoch Piotr Zielinski Covert Channels for Collusion in Online Computer Games. 355-370 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=3200&spage=355 2004 conf/ih/2004 Information Hiding db/conf/ih/ih2004.html#MurdochZ04