Iftach Haitner Alon Rosen Ronen Shaltiel On the (Im)Possibility of Arthur-Merlin Witness Hiding Protocols. 220-237 2009 TCC http://dx.doi.org/10.1007/978-3-642-00457-5_14 conf/tcc/2009 db/conf/tcc/tcc2009.html#HaitnerRS09