Yasuharu Katsuno Yuji Watanabe Sachiko Yoshihama Takuya Mishina Michiharu Kudo Layering negotiations for flexible attestation. 17-20 2006 STC http://doi.acm.org/10.1145/1179474.1179480 conf/ccs/2006stc db/conf/ccs/stc2006.html#KatsunoWYMK06