Certain embodiments consistent with the present invention involve a method
of selectively encrypting and decoding digital video content. Certain of
the packets are selected for encryption according to a selection
criterion, wherein the selected packets exclude packets containing start
of frame (SOF) headers. The selected packets are encrypted while
retaining the packets containing the SOF headers unencrypted to form
selectively encrypted digital video content. In decoding selectively
encrypted digital video content, offsets are calculated for at least one
of I frames and P frames from the SOF headers and the calculated offsets
are stored as an offset table. The offset table can then be accessed to
enable trick play of the selectively encrypted digital video content.