Encryption devices for use in a conditional access system
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United States of America Patent
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Jul 23, 2002
Issued Date -
N/A
app pub date -
Dec 16, 1999
filing date -
Apr 3, 1995
priority date (Note) -
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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 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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