System and method for transmitting entertainment information to authorized ones of plural receivers
First Claim
Patent Images
1. A subscription system decoding unit comprising:
- subscription show-key storing means for storing a plurality of subscription show-keys, selection of a proper one of said show-keys being required to decipher certain received enciphered commands;
show-key selecting means for selecting one of said subscription show-keys as an active show-key;
deciphering functions storage means for storing a plurality of deciphering functions;
function selecting means for selecting one of said deciphering functions as an active function;
command receiving means for receiving enciphered commands; and
deciphering means for deciphering said commands according to the active subscription show-key, extracting a deciphering function identification from a deciphered command, and supplying said deciphering function identification to said function selecting means to cause said function selecting means to select an active deciphering function.
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Reexamination
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Abstract
An audiovisual subscription system includes means for aperiodically inverting the lines of a transmitted video signal on a frame-by-frame basis and for decrypting encrypted PCM audio information which is transmitted along with the aperiodically inverted video information.
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Citations
11 Claims
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1. A subscription system decoding unit comprising:
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subscription show-key storing means for storing a plurality of subscription show-keys, selection of a proper one of said show-keys being required to decipher certain received enciphered commands; show-key selecting means for selecting one of said subscription show-keys as an active show-key; deciphering functions storage means for storing a plurality of deciphering functions; function selecting means for selecting one of said deciphering functions as an active function; command receiving means for receiving enciphered commands; and deciphering means for deciphering said commands according to the active subscription show-key, extracting a deciphering function identification from a deciphered command, and supplying said deciphering function identification to said function selecting means to cause said function selecting means to select an active deciphering function. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method performed by a subscription system for detecting a deciphering algorithm switch-over command comprising:
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receiving a plurality of switch-over commands, each containing a countdown value, over a period of time; detecting whether received countdown values a predetermined sequence; ignoring a switch-over command when said predetermined sequence is not followed; and switching over to a new deciphering algorithm at a predetermined point in said predetermined sequence. - View Dependent Claims (8, 9)
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10. A subscriber system including a digital data decrypting system comprising:
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a microprocessor; a memory means for storing program instructions for said microprocessor; a volatile programmable logic device, operatively coupled to said microprocessor, in which a digital data decrypting circuit is defined; a memory means for storing key values; wherein said microprocessor selects a specific one of said key values, based upon instructions transmitted to said subscriber system, as an active key to be used by said programmable logic device for directly decrypting encrypted data inputted into said programmable logic device. - View Dependent Claims (11)
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Specification