US Patent 7376233 Video slice and active region based multiple partial encryption

A selective encryption encoder and method of dual selective encryption. The selective encryption encoder has a packet identifier that identifies packets of at least one specified packet type, the at least one specified packet type being any of a plurality of packet types including packets containing a video slice headers or packets carrying data appearing in an active area of the image. A packet duplicator duplicates the identified packets to produce first and second sets of the identified packets. The packets are sent to and from a primary encryption encoder to encrypt the first set of identified packets under a first encryption method. A secondary encrypter encrypts the second set of identified packets under a second encryption method.