Ran Canetti Ling Cheung Dilsun Kirli Kaynar Nancy A. Lynch Olivier Pereira Compositional Security for Task-PIOAs. 125-139 2007 CSF http://dx.doi.org/10.1109/CSF.2007.15 conf/csfw/2007 db/conf/csfw/csf2007.html#CanettiCKLP07