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1. (WO1999007150) ENCRYPTION DEVICES FOR USE IN A CONDITIONAL ACCESS SYSTEM

Pub. No.:    WO/1999/007150    International Application No.:    PCT/US1998/016145
Publication Date: Fri Feb 12 00:59:59 CET 1999 International Filing Date: Sat Aug 01 01:59:59 CEST 1998
IPC: H04L 9/10
G09C 1/00
H04L 29/06
H04L 9/08
H04N 7/10
H04N 7/16
H04N 7/167
Applicants: SCIENTIFIC-ATLANTA, INC.
Inventors: PALGON, Michael, S.
PINDER, Howard, G.
Title: ENCRYPTION DEVICES FOR USE IN A CONDITIONAL ACCESS SYSTEM
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.