US5588058A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and device for scrambling and descrambling of a specific television broadcast
Assignee: US Philips Corp
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Filing: 1994-03-29
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Granted: 1996-12-24
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Expires: 2014-03-29
Abstract
Abstract A receiving device comprises a pseudo-random generator (18) initialized by a control word (CW) and a memory card reader (19). In accordance with the invention, it reads control word in a table of numbers contained in a read-only memory of a memory card (17) by utilizing a mode which is chosen from among several different modes, receives from the transmitter a signal which indicates the choice made in respect of said mode at a given instant.
Inventors
- 👤 Jacques Le Berre
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 12:59
CPC Classifications
H; H04; H04N; H04N7/00; H04N7/16; H04N7/167; H04N7/1675
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
260 words
A method of scrambling, at the level of a transmitter, and descrambling, at the level of receivers, a specific television transmission of limited duration, scrambling being performed by means of a pseudo-random generator which is initialized by a control word, descrambling involving the reconstruction upon reception, by means of a memory card device, of the control word which initializes a pseudo-random generator which is identical to that of the transmitter, said pseudo-random generator supplying the data necessary for descrambling, wherein in advance there are defined a table of numbers and different feasible modes of generating a control word by reading the table of numbers, and wherein the table is written into a read-only memory, the read-only memory being contained in descrambling cards issued to the users of receivers, after which at an instant of said specific television broadcast, the mode of reading a control word in the table is chosen in real time from among the various predefined feasible modes, which control word is read in conformity with said chosen mode in order to supply the control word to the transmitter in real tim, and immediately a signal is broadcast to the receivers so as to indicate a relavent mode of extracting the control word from the table, wherein the indicated mode corresponds to the chosen mode of the different feasible mode at the transmitter, as a result of which the receivers generate this control word according to the indicated mode from a descrambling card, the descrambling card comprising a simple memory in which the table of numbers is written.
Claim 2
Independent Claim
260 words
A method of scrambling, at the level of a transmitter, and descrambling, at the level of receivers, a specific television transmission of limited duration, scrambling being performed by means of a pseudo-random generator which is initialized by a control word, descrambling involving the reconstruction upon reception, by means of a memory card device, of the control word which initializes a pseudo-random generator which is identical to that of the transmitter, said pseudo-random generator supplying the data necessary for descrambling, wherein in advance there are defined a table of numbers and different feasible modes of generating a control word by reading the table of numbers, and wherein the table is written into a read-only memory, the read-only memory being contained in descrambling cards issued to the users of receivers, after which at an instant of said specific television broadcast, the mode of reading a control word in the table is chosen in real time from among the various predefined feasible modes, which control word is read in conformity with said chosen mode in order to supply the control word to the transmitter in real tim, and immediately a signal is broadcast to the receivers so as to indicate a relavent mode of extracting the control word from the table, wherein the indicated mode corresponds to the chosen mode of the different feasible mode at the transmitter, as a result of which the receivers generate this control word according to the indicated mode from a descrambling card, the descrambling card comprising a simple memory in which the table of numbers is written.
Claim 3
Dependent Claim
70 words
A method as claimed in claim 1, used in exceptional cases and wherein the control word is a first control word, whereas another scrambling method having a second control word transmitted in encrypted form so as to enable the receivers to reconstruct it by means of a key is normally used, whereby the first control word is identical to the second control word and is recurrently transmitted in encrypted form.
Claim 4
Dependent Claim
19 words
A method as claimed in claim 2, wherein a signal indicating that the transmission takes place is also transmitted.
Claim 5
Dependent Claim
36 words
A method as claimed in claim 1, wherein said mode of extracting the control word from the table consists in indicating an address in this table and of a mode for reading as from this address.
Claim 6
Dependent Claim
19 words
A method as claimed in claim 4, wherein the read mode consists in reading in descending order of addresses.
Claim 7
Dependent Claim
21 words
A method as claimed in claim 4, wherein the read mode consists in reading a data element every n data locations.
Claim 8
Dependent Claim
23 words
A method as claimed in claim 4, wherein the read mode consists in reading with an address value progression based on a calculation.
Claim 9
Dependent Claim
81 words
A transmitter device comprising a pseudo-random generator which is initialized by a control word, and a control word generator, said control word generator comprises means for reading the control word in a table of numbers by utilizing a chosen mode from among several different feasible modes, means for choosing a desired mode from the several feasible modes, and means for supplying receivers with a signal indicating which choice has been made in respect of the chosen mode at a given instant.
Claim 10
Dependent Claim
81 words
A transmitter device comprising a pseudo-random generator which is initialized by a control word, and a control word generator, said control word generator comprises means for reading the control word in a table of numbers by utilizing a chosen mode from among several different feasible modes, means for choosing a desired mode from the several feasible modes, and means for supplying receivers with a signal indicating which choice has been made in respect of the chosen mode at a given instant.
Claim 11
Dependent Claim
23 words
A transmitter device as claimed in claim 8, wherein said means for choosing a desired mode consist essentially of a random number generator.
Claim 12
Dependent Claim
110 words
A receiving device comprising a pseudo-random generator which is initialized by a control word and a memory card reader, wherein said receiving device comprises means for reading the control word in a table of numbers contained in a read-only memory of a descrambling memory card, utilizing a mode to be chosen from among several different modes, means for receiving from a transmitter a signal indicating the choice made at a given instant in respect of the chosen mode, and means for controlling a read mode of said means for reading the control word as a function of the signal received by said means for receiving the signal from the transmitter.
Claim 13
Dependent Claim
110 words
A receiving device comprising a pseudo-random generator which is initialized by a control word and a memory card reader, wherein said receiving device comprises means for reading the control word in a table of numbers contained in a read-only memory of a descrambling memory card, utilizing a mode to be chosen from among several different modes, means for receiving from a transmitter a signal indicating the choice made at a given instant in respect of the chosen mode, and means for controlling a read mode of said means for reading the control word as a function of the signal received by said means for receiving the signal from the transmitter.
Claim 14
Dependent Claim
35 words
A method as claimed in claim 2, wherein said mode of extracting the first control word from the table comprises indicating an address in this table and a mode for reading as from the address.
Claim 15
Dependent Claim
35 words
A method as claimed in claim 3, wherein said mode of extracting the first control word from the table comprises indicating an address in this table and a mode for reading as from the address.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1999-12-24 | 2000-06-24 | 2000-12-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-12-24 | 2004-06-24 | 2004-12-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-12-24 | 2008-06-24 | 2008-12-24 | $7700.00 | Window Closed / Lapsed |