Aggelos Kiayias Serdar Pehlivanoglu Tracing and Revoking Pirate Rebroadcasts. 253-271 2009 ACNS http://dx.doi.org/10.1007/978-3-642-01957-9_16 conf/acns/2009 db/conf/acns/acns2009.html#KiayiasP09