David Clark Sebastian Hunt Pasquale Malacaria A static analysis for quantifying information flow in a simple imperative language. 321-371 2007 15 Journal of Computer Security 3 http://iospress.metapress.com/openurl.asp?genre=article&issn=0926-227X&volume=15&issue=3&spage=321 db/journals/jcs/jcs15.html#ClarkHM07