A selective encryption encoder has a packet identifier that identifies
packets of a specified packet type forming a part of a program. A packet
duplicator duplicates the identified packets to produce first and second
sets of the identified packets. A PMT (program map table) inserter
generates temporary identifying information that identifies the first and
second sets of identified packets inserts the temporary identifying
information as user private data in a program map table (PMT) forming a
part of the transport program specific information (PSI). The data are
then sent to and received 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. The PSI is then modified at a PSI modifier to
remove the temporary identifying information and to correctly associate
the first and second sets of identified packets and the unencrypted
packets with the program.