Cryptography – Particular algorithmic function encoding – Nbs/des algorithm
Patent
1987-03-12
1989-03-28
Cangialosi, Salvatore
Cryptography
Particular algorithmic function encoding
Nbs/des algorithm
380 17, 380 21, 380 43, H04K 102
Patent
active
048171441
ABSTRACT:
A television signal scrambling system scrambles by suppressing horizontal syncs and changing the phase of the video carrier during the horizontal intervals. Data is transmitted by using two different widths for the horizontal intervals. Framing code information is sent by means of long pulses of two different durations during the vertical blanking interval. Three filters are utilized for dynamic scrambling, with filters A and B defining one scrambling mode and A and C defining a second scrambling mode. Corresponding descrambling filters are included in subscriber terminals and the subscriber microprocessor controllers have information downloaded as to the filter pairs to be used for descrambling based upon the receipt of the first or second framing code and a mode definition. The mode definitions are in the form of encrypted data and are dynamically changed by downloading to the subscriber terminals.
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patent: 4484025 (1984-11-01), Ostermann et al.
patent: 4531020 (1985-07-01), Wechselberger et al.
patent: 4590519 (1986-05-01), Zelenz
patent: 4716588 (1987-12-01), Thompson et al.
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Citta Richard W.
Gosc Paul M.
Mutzabaugh Dennis
Sgrignoli Gary J.
Cangialosi Salvatore
Zenith Electronics Corporation
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