04712239 is referenced by 168 patents and cites 3 patents.

A method and apparatus prevent unauthorized programming viewing via a downloadable cable television converter. A booter checksum is computed from data contained in a downloaded booter image. A valid checksum is extracted from tag data associated with a scrambled program signal transmitted on the cable system. The booter checksum is compared to the extracted valid checksum. If the booter checksum and valid checksums match, a descrambler is enabled to descramble the scrambled program signal. If the checksums do not match, the descrambler is not enabled. In this manner, a pirate is prevented from downloading a false booter image to defeat the integrity of the converter.

Title
Security arrangement for downloadable cable television converters
Application Number
6/874845
Publication Number
4712239
Application Date
June 16, 1986
Publication Date
December 8, 1987
Inventor
Richard Westerfer
Norristown
PA, US
Robert Simons
Lansdale
PA, US
William Frezza
Warminster
PA, US
Agent
Barry R Lipsitz Esq
Assignee
General Instrument Corporation
NY, US
IPC
H04L 9/00
H04N 7/167
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