Dieter Hutter Axel Schairer Possibilistic Information Flow Control in the Presence of Encrypted Communication. 209-224 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=3193&spage=209 2004 conf/esorics/2004 ESORICS db/conf/esorics/esorics2004.html#HutterS04