Descrambler subscriber key production system utilizing key seeds stored in descrambler

• US 4,634,808 A
• Filed: 03/15/1984
• Issued: 01/06/1987
• Est. Priority Date: 03/15/1984
• Status: Expired due to Term

• Current Assignee: General Instrument Corporation (CommScope Holding Company, Inc.)
• Original Assignee: MACOM Technology Solutions Holdings, Inc.
• Inventors: Moerder, Karl E.
• Primary Examiner(s): Cangialosi, Salvatore
• Assistant Examiner(s): Lewis, Aaron J.
• Application Number:
  US06/589,741
• Time in Patent Office: 1,027 Days
• Field of Search: 178/22.09, 178/22.13, 178/22.15, 178/22.11, 178/22.16, 178/22.14, 358/114, 358/122, 358/124
• US Class Current: 380/29
• CPC Class Codes: H04N 7/1675 Providing digital key or authorisation information for generation or regeneration of the scrambling sequence pseudo-random number generators in general G06F7/58

Abstract

A system for reproducing in a descrambler of a subscriber communication network a subscriber key signal that is unique to the descrambler and was used in encrypting a key signal that must be decrypted for use in descrambling a signal received by the descrambler. The scrambled signal is received by the descrambler together with the encrypted key signal and a key generation number containing an address for accessing a predetermined area in a memory contained in the descrambler. The system includes a circuit for providing a subscriber key generation signal that is unique to the descrambler; a subscriber key generator for reproducing the unique subscriber key signal by processing the subscriber key generation signal in accordance with a predetermined encryption algorithm upon the algorithm being keyed by a prescribed subscriber key seed signal that is unique to the descrambler; a secure memory storing a plurality of different subscriber key seed signals, and for providing the prescribed seed signal to key the algorithm when the area of the memory containing the prescribed seed signal is accessed by the address contained in the received key generation number; and a circuit for accessing the first memory with the address contained in the received key generation number. The subscriber key generation signal is formed by combining the received key generation number with a unique subscriber address signal that is stored in a second memory of the descrambler.

Claims

1. A system for reproducing in a descrambler a subscriber key signal that is unique to the descrambler and was used in encrypting a key signal that must be decrypted for use in descrambling a signal received by the descrambler, wherein the scrambled signal is received by the descrambler together with the encrypted key signal and an address for accessing a predetermined area in a memory contained in the descrambler, the system comprising

means for providing a subscriber key generation signal;

a subscriber key generator for reproducing said unique subscriber key signal by processing the subscriber key generation signal in accordance with a predetermined encryption algorithm upon said algorithm being keyed by a prescribed subscriber key seed signal that is unique to the descrambler;

a first memory storing the prescribed subscriber key seed signal, and for providing the prescribed seed signal to key the algorithm when the area of the memory containing the prescribed seed signal is accessed by the address received with the received key generation number; and

means for accessing the first memory with the received address.

2. A system according to claim 1, wherein the first memory stores a plurality of different subscriber key seed signals, with the prescribed one of said seed signals being provided to key the algorithm in accordance with the received address.

3. A system according to claim 2, wherein the first memory is a secure memory.

4. A system according to claim 1, wherein the first memory is a secure memory.

5. A system according to claim 1, wherein a key generation number also is received by the descrambler and wherein the means for providing the subscriber key generation signal comprises

a second memory storing a subscriber address signal that is unique to the descrambler;

and

means for combining the stored subscriber address signal and the received key generation number to provide the subscriber key generation signal.

6. A system according to claim 5, wherein the first memory stores a plurality of different subscriber key seed signals, with the prescribed one of said seed signals being provided to key the algorithm in accordance with the address received with the received key generation number.

7. A system according to claim 6, wherein the first memory is a secure memory.

8. A system according to claim 1,

wherein the means for providing the subscriber key generation signal comprises a second key generator for producing the subscriber key generation signal by processing a signal derived from a signal containing a subscriber address that is unique to the descrambler in accordance with a second predetermined encryption algorithm upon said second algorithm being keyed by a second prescribed key seed signal that is unique to the descrambler;

and

wherein the first memory also stores the second prescribed seed signal and provides the second prescribed seed signal to key the second algorithm when the area of the first memory containing the second prescribed seed signal also is accessed by the received address.

9. A system according to claim 8, wherein a key generation number also is received by the descrambler and wherein the means for providing the subscriber key generation signal further comprises

a second memory storing a subscriber address signal that is unique to the descrambler;

and

means for combining the stored subscriber address signal and the received key generation number to provide said subscriber address containing signal.

10. A system according to claim 9,

wherein the means for providing the subscriber key generation signal further comprises a third key generator for producing said signal derived from said subscriber address containing signal by processing said subscriber address containing signal in accordance with a third predetermined encryption algorithm upon said third algorithm being keyed by a prescribed key seed signal that is stored in the first memory and is unique to the descrambler;

and

wherein the first memory provides the prescribed key seed signal for keying the third algorithm when the area of the first memory containing said seed signal for keying the third algorithm is accessed by the address received with the received key generation number.

11. A system according to claim 10, wherein the same prescribed key seed signal is provided by the first memory for keying two of the algorithms.

12. A system according to claim 10, wherein the first memory is a secure memory.

13. A system according to claim 8,

wherein the means for providing the subscriber key generation signal further comprises a third key generator for producing said signal derived from said subscriber address containing signal by processing said subscriber address containing signal in accordance with a third predetermined encryption algorithm upon said third algorithm being keyed by a prescribed key seed signal that is stored in the first memory and is unique to the descrambler;

and

wherein the first memory provides the prescribed key seed signal for keying the third algorithm when the area of the first memory containing said seed signal for keying the third algorithm is accessed by the address received with the received key generation number.

14. A system according to claim 13, wherein the same prescribed key seed signal is provided by the first memory for keying two of the algorithms.

15. A system according to claim 13, wherein the first memory is a secure memory.

16. A system according to claim 1,

wherein the means for providing the subscriber key generation signal comprises a second key generator for producing the subscriber key generation signal by processing a signal containing a subscriber address that is unique to the descrambler in accordance with a second predetermined encryption algorithm upon said second algorithm being keyed by a second prescribed key seed signal that is unique to the descrambler, and

wherein the first memory also stores the second prescribed key seed signal and provides the second prescribed seed signal to key the second algorithm when the area of the first memory containing the second prescribed seed signal also is accessed by the received address.

17. A system according to claim 16, wherein a key generation number also is received by the descrambler and wherein the means for providing the subscriber key generation signal further comprises

a second memory storing a subscriber address signal that is unique to the descrambler;

and

means for combining the stored subscriber address signal and the received key generation number to provide said subscriber address containing signal.

18. A system according to claim 16, wherein the first memory is a secure memory.

19. In a subscriber communication network, wherein a common key signal is uniquely encrypted for each of a plurality of subscribers and must be decrypted by the use of a subscriber key signal that is unique for each subscriber for use in descrambling a scrambled signal, and wherein each subscriber has a descrambler for descrambling the scrabled signal, a system for reproducing in each descrambler, the subscriber key signal that is unique to such descrambler, wherein the scrambled signal is received by the descrambler together with the uniquely encrypted common key signal, a key generation number that is common to a group of the descramblers in the network and an address for accessing a predetermined area in a memory contained in each descrambler, the system comprising:

means for providing a subscriber key generation signal;

a subscriber key generator for reproducing said unique subscriber key signal by processing the subscriber key generation signal in accordance with a predetermined encryption algorithm upon said algorithm being keyed by a prescribed subscriber key seed signal that is unique to the descrambler;

a first memory storing the prescribed subscriber key seed signal, and for providing the prescribed seed signal to key the algorithm when the area of the memory containing the prescribed seed signal is accessed by the address received with the received key generation number; and

means for accessing the first memory with the address received with the received key generation number.

20. A system according to claim 19, wherein the first memory stores a plurality of different subscriber key seed signals, with the prescribed one of said seed signals being provided to key the algorithm in accordance with the address received with the received key generation number.

21. A system according to claim 19, wherein the means for providing the subscriber key generation signal comprises

a second memory storing a subscriber address signal that is unique to the descrambler;

and

means for combining the stored subscriber address signal and the received key generation number to provide the subscriber key generation signal.

22. In a subscriber communication network wherein a common key signal is uniquely encrypted for a subscriber by a plurality of different scrambled signal broadcasters and must be decrypted by using a subscriber key signal that is unique to both the subscriber and the broadcaster for use in descrambling a scrambled signal, and wherein the subscriber has a descrambler for descrambling the scrambled signal from a given one of the broadcastes by using the subscriber key signal that is unique to the given broadcaster to decrypt the uniquely encrypted key signal, a system for reproducing in the descrambler the subscriber key signal that is unique to the given broadcaster, wherein the scrambled signal from the given broadcaster is received by the descrambler together with the uniquely encrypted key signal, a key generation number that is unique to the given broadcaster and, an address for accessing a predetermined area in a memory contained in the descrambler, the system comprising

means for providing a subscriber key generation signal;

a subscriber key generator for reproducing said unique subscriber key signal by processing the subscriber key generation signal in accordance with a predeterined encryption algorithm upon said algorithm being keyed by a prescribed subscriber key seed signal that is unique to the descrambler;

a first memory storing the prescribed subscriber key seed signal, and for providing the prescribed seed signal to key the algorithm when the area of the memory containing the prescribed seed signal is accessed by the address received with the received key generation number; and

means for accessing the first memory with the address received with the received key generation number.

23. A system according to claim 22, wherein the first memory stores a plurality of different subscriber key seed signals, with the prescribed one of said seed signals being provided to key the algorithm in accordance with the address received with the received key generation number.

24. A system according to claim 23, wherein the means for providing the subscriber key generation signal comprises:

a second memory storing a subscriber address signal that is unique to the descrambler; and

means for combining the stored subscriber address signal and the received key generation number to provide the subscriber key generation signal.