Abhilasha Bhargav-Spantzel Anna Cinzia Squicciarini Elisa Bertino Establishing and protecting digital identity in federation systems. 269-300 2006 14 Journal of Computer Security 3 http://iospress.metapress.com/openurl.asp?genre=article&issn=0926-227X&volume=14&issue=3&spage=269 db/journals/jcs/jcs14.html#Bhargav-SpantzelSB06