Cryptography – Key management – Having particular key generator
Patent
1987-09-22
1990-03-06
Tarcza, Thomas H.
Cryptography
Key management
Having particular key generator
380 5, 380 7, 380 20, 235382, 358 84, 455 2, H04N 7167, G06K 500
Patent
active
049072730
ABSTRACT:
A high security pay television system is provided in which subscribers are provided with a decoder and with periodically changed removable memory modules. The decoder only functions to properly descramble the scrambled broadcast signal when a changeable system-wide code is available in the decoder. The code can either be carried in the memory module, or an internal code unique to the decoder and resident in the decoder can be combined with a external code in the removable memory module, and also unique to that decoder, to generate the common systemwide system code. Program viewership is written on the removable memory module. The removable memory module is provided with a pre-written limit of program viewing authorization so that when the limit is reached, further viewing is not possible.
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Tarcza Thomas H.
Wallace Linda J.
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