Content scrambling with minimal impact on legacy devices

摘要

A method of encrypting a digital television signal involves examining unencrypted packets of data in the digital television signal to identify a selected packet type; duplicating packets identified as being of a selected packet type to produce pairs of duplicated packets; encrypting one of each pair of the duplicated packets; inserting the encrypted packets along with the unencrypted packets of the selected packet type to the digital television signal along with the unencrypted packets of data that are not of the selected packet type into produce a selectively encrypted digital television signal that contains duplicate packets of the selected packet type with one of the duplicate packets being encrypted while the other of the duplicated packets remains unencrypted; and broadcasting the selectively encrypted television signal. This abstract is not to be considered limiting, since other embodiments may deviate from the features described in this abstract.