Broadcasting variants of digital signals in a conditional access system
First Claim
1. A headend system comprising:
- a duplicator configured to generate two or more copies of at least a part of a first digital signal;
one or more scramblers configured to scramble each copy to obtain scrambled copies, wherein each copy is scrambled differently; and
a combiner configured to combine the scrambled copies to obtain a second digital signal within which the scrambled copies are not identifiable as being related to one of the two or more copies of the at least a part of the first digital signal so that descrambling, at a receiver of the second digital signal, of the scrambled copies using a decryption key for one of the scrambled copies descrambles said one of the scrambled copies into a meaningful output and all other scrambled copies into a non-meaningful output that an error handler of the receiver discards.
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Accused Products
Abstract
The invention provides a headend system, a receiver, a smartcard and a conditional access system enabling distribution of multiple variants of a part of a digital signal, such as multiple variants of an audio part or a video part of a data stream, without requiring receivers to be updated. The digital signal generated by the headend system enables a receiver to receive and process the digital signal without requiring identification of the copies in the second digital signal. Error handling capabilities of the receiver ensure that only one copy is used in the output of the receiver. The error handling capabilities are triggered by having the receiver use one decryption key for descrambling all copies, resulting in one copy being descrambled correctly and the other copies being descrambled incorrectly.
15 Citations
18 Claims
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1. A headend system comprising:
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a duplicator configured to generate two or more copies of at least a part of a first digital signal; one or more scramblers configured to scramble each copy to obtain scrambled copies, wherein each copy is scrambled differently; and a combiner configured to combine the scrambled copies to obtain a second digital signal within which the scrambled copies are not identifiable as being related to one of the two or more copies of the at least a part of the first digital signal so that descrambling, at a receiver of the second digital signal, of the scrambled copies using a decryption key for one of the scrambled copies descrambles said one of the scrambled copies into a meaningful output and all other scrambled copies into a non-meaningful output that an error handler of the receiver discards. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 15, 18)
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12. A method for use in a headend system, the method comprising the steps of:
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generating two or more copies of at least a part of a first digital signal; scrambling each copy to obtain scrambled copies of the least a part of the first digital signal, wherein each copy is scrambled differently; and combining the scrambled copies to obtain a second digital signal within which the scrambled copies are not identifiable as being related to one of the two or more copies of the least a part of the first digital signal so that descrambling, at a receiver of the second digital signal, of the scrambled copies using a decryption key for one of the scrambled copies descrambles said one of the scrambled copies into a meaningful output and all other scrambled copies into a non-meaningful output that an error handler of the receiver discards. - View Dependent Claims (13, 16)
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14. A method for use in a hardware smartcard the method comprising the steps of:
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receiving an entitlement message from a receiver, the entitlement message comprising key data for two or more decryption keys, the entitlement message further comprising the selection data; decrypting the entitlement message to obtain the key data and the selection data; reading the fingerprint vector from a memory; matching the selection data with the fingerprint vector to obtain a matching result; and obtaining the one decryption key from the key data based on the matching result to enable the receiver to descramble a first scrambled copy of a digital signal into the meaningful output and to descramble a second scrambled copy of the digital signal into the non-meaningful output that an error handler of the receiver discards.
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17. A non-transitory computer readable storage medium storing one or more programs, the one or more programs comprising instructions which, when executed by a computer processor cause the computer processor to perform a method comprising:
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generating two or more copies of at least a part of the first digital signal; scrambling each copy to obtain scrambled copies of the at least a part of the first digital signal, wherein each copy is scrambled differently; and combining the scrambled copies to obtain a second digital signal within which the scrambled copies are not identifiable as being related to one of the two or more copies of the at least a part of the first digital signal so that descrambling, at a receiver of the second digital signal, of the scrambled copies using a decryption key for one of the scrambled copies descrambled said one of the scrambled copies into a meaningful output and all other scrambled copies into a non-meaningful output that an error handler of the receiver discards.
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Specification