Method for partially encrypting program data
First Claim
1. A method for providing an instance in a conditional access system, the method comprising the steps of:
- selecting for encryption a digital bit stream from a plurality of digital bit streams using a packet identifier;
encrypting the selected digital bit stream according to a first level encryption method to provide an encrypted instance prior to combining the encrypted instance with the plurality of digital bit streams to provide a partially-encrypted bit stream; and
transmitting the partially-encrypted bit stream.
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Accused Products
Abstract
A cable television system provides conditional access to services. The cable television system includes a headend from which service “instances,” or programs, are broadcast and a plurality of set top units for receiving the instances and selectively decrypting the instances for display to system subscribers. The service instances are partially-encrypted using public and/or private keys provided by service providers or central authorization agents. Keys used by the set tops for selective decryption may also be public or private in nature, and such keys may be reassigned at different times to provide a cable television system in which piracy concerns are minimized.
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Citations
22 Claims
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1. A method for providing an instance in a conditional access system, the method comprising the steps of:
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selecting for encryption a digital bit stream from a plurality of digital bit streams using a packet identifier; encrypting the selected digital bit stream according to a first level encryption method to provide an encrypted instance prior to combining the encrypted instance with the plurality of digital bit streams to provide a partially-encrypted bit stream; and transmitting the partially-encrypted bit stream. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method for providing a program in a conditional access system, the method comprising the steps of:
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selecting for encryption a portion of the program from a multimedia transport stream using a packer identifier; encrypting a portion of the program prior to combining the encrypted portion and the remaining portion of the program with the multimedia transport stream; and
transmitting the combined stream. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22)
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Specification