Cryptography – Particular algorithmic function encoding – Nbs/des algorithm
Patent
1984-05-11
1988-02-23
Buczinski, Stephen C.
Cryptography
Particular algorithmic function encoding
Nbs/des algorithm
380 37, 380 46, H04N 7167
Patent
active
047275790
ABSTRACT:
A television receiver for receiving scrambled television signals has an arrangement (3) which provides scrambled video components (V) and packet arranged sound/data components (D) some of which are also scrambled. The components (D) are applied to a packet demultiplexer (4) where the packets are assembled from the data in several lines in the signal to provide at a first output (P), the respective packets carrying sound/data information and, at a second output (E), encrypted control data which is applied to a sub-system (6) to produce a video scrambling control word (VS) for each line of the video components. The sub-system (6) during each line produces further bits which are applied to a descrambling control word generator (7) which assembles these further bits from three lines to form a packet scrambling control word. This control word and the packets associated with it are added in an adder (5) and applied to a main packet buffer store (8) from which each packet is read out by a packet selector (9), and the packet is applied to a packet descrambler (12) while the packet scrambling control word is selected by a register (11) and used to control the generation of a binary sequence by a pseudo random binary sequence generator (13), this sequence being added to the packet in the descrambler (12), modulo-two, to achieve descrambling. A packet identifier (10) examines the packet address to ensure the packet requires descrambling and inhibits the generator (13) should descrambling not be required. With such a receiver the control data (E) can be used for controlling descrambling of both the video and the sound/data components.
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Crowther Gerald O.
Wright Derek T.
Briody Thomas A.
Buczinski Stephen C.
Gadson Gregory P.
Streeter William J.
U.S. Philips Corporation
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