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专利名称：Method and apparatus for geographically
limiting service in a conditional accesssystem
发明人：Glendon L. Akins, III,Howard G.
Pinder,Anthony J. Wasilewski
申请号：US09493409申请日：20000128公开号：US06560340B1公开日：20030506
专利附图：
摘要：A cable television system provides conditional access to services. The cable
television system includes a headend from which service “instances”, or programs, arebroadcast and a plurality of set top units for receiving the instances and selectivelydecrypting the instances for display to system subscribers. The service instances areencrypted using public and/or private keys provided by service providers or centralauthorization agents. Keys used by the set tops for selective decryption may also bepublic or private in nature, and such keys may be reassigned at different times to providea cable television system in which piracy concerns are minimized.
申请人：SCIENTIFIC-ATLANTA, INC.
代理人：Kenneth M. Massaroni,Hubert J. Barnhardt III,Shelley L. Couturier
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