US5406627A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Digital data cryptographic system
Assignee: NEC Corp of America
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Filing: 1992-12-28
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Granted: 1995-04-11
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Expires: 2012-12-28
Abstract
Abstract An audiovisual subscription system includes means for aperiodically inverting the lines of a transmitted video signal on a frame-by-frame basis and for decrypting encrypted PCM audio information which is transmitted along with the aperiodically inverted video information.
Inventors
- 👤 John R. Thompson
- 👤 C. J. Hunting
- 👤 William L. Phipps
- 👤 Steven J. Raynesford
- 👤 Philip H. Rittmueller
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 17:57
CPC Classifications
H; H04; H04K; H04K1/00; H04K1/02; H04N; H04N7/00; H04N7/16; H04N7/167; H04N7/1675; H04N7/171; H04N7/1716
Claims Analysis
Total Claims: 25
Claim 1
Independent Claim
108 words
A system comprising: a receiving means for receiving a transmitted signal, said transmitted signal including encrypted digital data and including commands for designating one of a plurality of decryption keys stored in said receiving means, said receiving means comprising: decryption key storage means for storing a plurality of decryption keys; decryption key selection means for selecting one of said plurality of decryption keys as an active key based upon said commands received by said receiving means; decryption function storage means for storing one or more decryption functions; and digital data decryption means for decrypting said encrypted digital data based upon one of said functions and said active key.
Claim 2
Independent Claim
108 words
A system comprising: a receiving means for receiving a transmitted signal, said transmitted signal including encrypted digital data and including commands for designating one of a plurality of decryption keys stored in said receiving means, said receiving means comprising: decryption key storage means for storing a plurality of decryption keys; decryption key selection means for selecting one of said plurality of decryption keys as an active key based upon said commands received by said receiving means; decryption function storage means for storing one or more decryption functions; and digital data decryption means for decrypting said encrypted digital data based upon one of said functions and said active key.
Claim 3
Dependent Claim
29 words
The system of claim 1 wherein said commands are transmitted to said receiving means in an encrypted format and decrypted by a command decryption means within said receiving means.
Claim 4
Dependent Claim
27 words
The system of claim 2 wherein said command decryption means uses a decryption key contained in a ROM for decrypting said commands to identify said active key.
Claim 5
Dependent Claim
37 words
The system of claim 1 wherein said decryption function storage means stores a plurality of functions, and wherein said commands identify one of said functions as well as an active key to decrypt said encrypted digital data.
Claim 6
Dependent Claim
35 words
The system of claim 1 wherein said digital data decryption means is a programmable logic device (PLD) which is programmed with said functions and said active key in order to decrypt said encrypted digital data.
Claim 7
Dependent Claim
22 words
The system of claim 5 wherein said encrypted digital data is inputted into said PLD and is directly decrypted by said PLD.
Claim 8
Dependent Claim
14 words
The system of claim 5 wherein said decryption key storage means is said PLD.
Claim 9
Dependent Claim
14 words
The system of claim 5 wherein said decryption function storage means is said PLD.
Claim 10
Dependent Claim
31 words
The system of claim 5 wherein said commands control a microprocessor to select an active key and program said PLD to use said active key to decrypt said encrypted digital data.
Claim 11
Dependent Claim
13 words
The system of claim 1 wherein said encrypted digital data is audio information.
Claim 12
Dependent Claim
12 words
The system of claim 1 wherein said system is a subscriber system.
Claim 13
Dependent Claim
53 words
The system of claim 1 further comprising a transmitting means for encrypting digital data using a selected one of a plurality of encryption keys and a selected enciphering function and for transmitting said encrypted digital data along with said commands designating said active key selected from one of said plurality of decryption keys.
Claim 14
Independent Claim
115 words
A system, including a digital data decrypting system, comprising: a microprocessor; a programmable logic device (PLD), operatively coupled to said microprocessor, in which a digital data decryption circuit is defined; and a memory means for storing a plurality of decryption key values, wherein said microprocessor selects a specific one of said key values, based upon instructions transmitted to said system, as an active key to be used by said PLD for directly decrypting encrypted data inputted into said PLD, and wherein said PLD stores a plurality of decryption functions, and said instructions designate one of said decryption functions as well as an active key to be used by said PLD to decrypt said encrypted data.
Claim 15
Independent Claim
115 words
A system, including a digital data decrypting system, comprising: a microprocessor; a programmable logic device (PLD), operatively coupled to said microprocessor, in which a digital data decryption circuit is defined; and a memory means for storing a plurality of decryption key values, wherein said microprocessor selects a specific one of said key values, based upon instructions transmitted to said system, as an active key to be used by said PLD for directly decrypting encrypted data inputted into said PLD, and wherein said PLD stores a plurality of decryption functions, and said instructions designate one of said decryption functions as well as an active key to be used by said PLD to decrypt said encrypted data.
Claim 16
Dependent Claim
12 words
The system of claim 13 wherein said encrypted data contains audio information.
Claim 17
Dependent Claim
24 words
The system of claim 13 wherein said instructions are transmitted in encrypted form and are decrypted by a decrypting means within said decrypting system.
Claim 18
Dependent Claim
51 words
The system of claim 13 further comprising a digital data encrypting system for encrypting data and transmitting said encrypted data and said instructions to said digital data decrypting system, said instructions identifying a decryption key within said memory means to be used as an active key to decrypt said encrypted data.
Claim 19
Dependent Claim
12 words
The system of claim 13 wherein said memory means is said PLD.
Claim 20
Independent Claim
92 words
A system, including a digital data decrypting system, comprising: a programmable logic device (PLD) in which a digital data decryption circuit is defined, said PLD storing a plurality of decryption functions; memory means for storing a plurality of decryption key values; and means for selecting a specific one of said key values as an active key, based upon instructions transmitted to said system, and for selecting a specific one of said decryption functions as an active function to be used by said PLD for directly decrypting encrypted data inputted into said PLD.
Claim 21
Independent Claim
92 words
A system, including a digital data decrypting system, comprising: a programmable logic device (PLD) in which a digital data decryption circuit is defined, said PLD storing a plurality of decryption functions; memory means for storing a plurality of decryption key values; and means for selecting a specific one of said key values as an active key, based upon instructions transmitted to said system, and for selecting a specific one of said decryption functions as an active function to be used by said PLD for directly decrypting encrypted data inputted into said PLD.
Claim 22
Dependent Claim
12 words
The system of claim 18 wherein said encrypted data contains audio information.
Claim 23
Dependent Claim
24 words
The system of claim 18 wherein said instructions are transmitted in encrypted form and are decrypted by a decrypting means within said decrypting system.
Claim 24
Dependent Claim
51 words
The system of claim 18 further comprising a digital data encrypting system for encrypting data and transmitting said encrypted data and said instructions to said digital data decrypting system, said instructions identifying a decryption key within said memory means to be used as an active key to decrypt said encrypted data.
Claim 25
Dependent Claim
12 words
The system of claim 18 wherein said memory means is said PLD.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1998-04-10 | 1998-10-10 | 1999-04-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-04-10 | 2002-10-10 | 2003-04-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-04-10 | 2006-10-10 | 2007-04-11 | $7700.00 | Window Closed / Lapsed |