System and method for partially encrypted multimedia stream
First Claim
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1. A method for multimedia transmission, comprising:
- generating at least two copies of a multimedia stream to render first and second clear stream copies;
sending the first clear stream copy to a first conditional access (CA) component to encrypt the entire first clear stream copy to render a first completely encrypted stream;
sending the second clear stream copy to a second conditional access (CA) component to encrypt the entire second clear stream copy to render a second completely encrypted stream;
identifying predetermined portions of the multimedia stream, the predetermined portions being a subset of portions of the multimedia stream and having respective encrypted versions in the first completely encrypted stream and in the second completely encrypted stream;
obtaining the encrypted versions of the predetermined portions from the first completely encrypted stream;
obtaining encrypted versions of the predetermined portions from the second completely encrypted stream;
substituting the encrypted predetermined portions obtained from both the first and second completely encrypted streams for the predetermined portions in the multimedia stream or in a duplicate clear copy thereof to render a transmission stream that is only partially encrypted for transmission thereof.
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Abstract
A multimedia stream head end includes a legacy conditional access (CA) device that fully encrypts the stream using legacy keys. A copy of the stream is sent to a secondary CA device that encrypts only critical packets in the stream using secondary keys to render a partially encrypted stream. The critical packets in the fully encrypted stream from the legacy CA device are obtained and inserted next to the corresponding critical packets in the partially encrypted stream. Thus, only critical packets are encrypted, with encrypted versions being generated by both the legacy CA and secondary CA without the legacy CA knowing which of the packets that it encrypts are “critical”.
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Citations
17 Claims
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1. A method for multimedia transmission, comprising:
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generating at least two copies of a multimedia stream to render first and second clear stream copies; sending the first clear stream copy to a first conditional access (CA) component to encrypt the entire first clear stream copy to render a first completely encrypted stream; sending the second clear stream copy to a second conditional access (CA) component to encrypt the entire second clear stream copy to render a second completely encrypted stream; identifying predetermined portions of the multimedia stream, the predetermined portions being a subset of portions of the multimedia stream and having respective encrypted versions in the first completely encrypted stream and in the second completely encrypted stream; obtaining the encrypted versions of the predetermined portions from the first completely encrypted stream; obtaining encrypted versions of the predetermined portions from the second completely encrypted stream; substituting the encrypted predetermined portions obtained from both the first and second completely encrypted streams for the predetermined portions in the multimedia stream or in a duplicate clear copy thereof to render a transmission stream that is only partially encrypted for transmission thereof. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A system for use in a digital stream transmitter head end having a legacy Conditional access (CA) device completely encrypting a multimedia Stream to render a legacy-encrypted stream, comprising:
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at least a system CA device completely encrypting a copy of the multimedia stream to render a system-encrypted stream; and a reconstitution component combining, into the multimedia stream, only predetermined portions from the system-encrypted stream and the same predetermined portions from the legacy-encrypted stream to render a partially encrypted stream having both a first encrypted version of the predetermined portions and a second encrypted version of the predetermined portions and having substantially no other encrypted data therein. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17)
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Specification