A method for producing and for subsequently decrypting a protected stream
of compressed video content is described herein. The method includes
receiving an input stream of compressed video content containing a
sequence of frames. A set of encrypted frames are created by encrypting
selected frames of the sequence of frames in accordance with a frame
encryption function. The method further includes generating frame
decryption information necessary to decrypt the set of encrypted frames.
In a particular implementation the protected stream is assembled using
the set of encrypted frames, unencrypted frames from the input stream,
and the frame decryption information. The decryption process is initiated
by receiving the protected stream of compressed video content and the
corresponding frame decryption information. In this regard the frame
decryption information includes data distinguishing the encrypted frames
from the unencrypted frames of the compressed video content within the
protected stream. The encrypted frames are then decrypted in accordance
with the frame decryption information.