Method for partially encrypting program data
OwnerAnthony J. Wasilewski, Howard G. Pinderinventors
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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.
Claims18
A method for providing a plurality of programs in a conditional access system, the method comprising the steps of:
- using a packet identifier to select for encryption a portion of each of a plurality of digital bit streams from a multimedia transport stream according to a plurality of at least a first and a second encryption methods;
- encrypting the selected portion of each of the plurality of digital bit streams prior to combining the encrypted portion and the unencrypted portion with the transport stream;
- and
- transmitting the combined stream.
A method for providing a plurality of programs in a conditional access system, the method comprising the steps of:
- using a packet identifier to select for encryption a portion of a plurality of elementary bit streams from a plurality of programs according to a plurality of at least a first and a second encryption methods;
- encrypting the selected portion of each of the plurality of elementary bit streams from said plurality of programs prior to combining the encryption portion and the remaining portion of the streams with said plurality of programs to provide a partially-encrypted stream;
- and
- transmitting the partially-encrypted stream.
Dependencies are inferred from the claim text.