1. A selective encryption method, comprising: examining unencrypted packets of data in the digital video signal to identify a specified packet type; duplicating the packets of the specified packet type to produce duplicate packets; identifying the duplicate packets by a first packet identifier (PID); identifying remaining unencrypted packets by a second packet identifier (PID); replacing the packets of the specified packet type with the first duplicate packets; generating identifying information that identifies the first duplicate packets, and the unencrypted packets; storing the identifying information as transport program specific information (PSI); creating a data stream comprising the PSI, the first duplicate packets, and the unencrypted packets into the data stream; and sending the data stream to a primary encryption encoder.