| 摘要 |
A method for providing keys for descrambling scrambled content, the scrambled content being divided into frames, the method including: identifying a plurality of frames to be descrambled; for each frame of the plurality of frames, identifying a key period associated with a key for descrambling the frame; and for at least one frame f of the plurality of frames, substituting a substitute frame g for the frame f, the substitute frame g being chosen in order to reduce a total number of key periods associated with keys for descrambling all of the plurality of frames. Related apparatus and methods are also provided.
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