A cable distribution system that includes a head end connected to a plurality of customer devices through a transmission network that includes a remote fiber node that converts digital data to analog data suitable for the plurality of customer devices, where the head end includes a processor. A packetized elementary stream of a video is provided from the head end to customer devices through the transmission network, wherein the packetized elementary stream includes a plurality of groups comprising pairs of packetized elementary stream headers and packetized elementary stream payloads. A first one of the plurality of groups corresponding to a non-predicted coded picture of the video of the packetized elementary stream is determined. The first one of the plurality of groups is encrypted while not encrypting all of the plurality of groups of the video. A signal is provided from a conditional access system to a selected one of the plurality of customers that is suitable to be used to decrypt the first one of the plurality of groups.