Li Weng Karel Wouters Bart Preneel Extending the Selective MPEG Encryption Algorithm PVEA. 117-120 2006 conf/iih-msp/2006 IIH-MSP http://doi.ieeecomputersociety.org/10.1109/IIH-MSP.2006.97 db/conf/iih-msp/iih-msp2006.html#WengWP06