Abhilasha Bhargav-Spantzel Anna Cinzia Squicciarini Elisa Bertino Establishing and protecting digital identity in federation systems. 11-19 2005 conf/dim/2005 Digital Identity Management http://doi.acm.org/10.1145/1102486.1102489 db/conf/dim/dim2005.html#Bhargav-SpantzelSB05