Data communication system

• US 6,766,024 B1
• Filed: 08/31/1999
• Issued: 07/20/2004
• Est. Priority Date: 09/01/1998
• Status: Expired due to Fees

• Current Assignee: Mindport BV
• Original Assignee: Mindport BV
• Inventors: Rix, Simon Paul Ashley
• Primary Examiner(s): Barŕ;on, Gilberto
• Assistant Examiner(s): NOBAHAR, ABDULHAKIM
• Application Number:
  US09/386,184
• Time in Patent Office: 1,785 Days
• Field of Search: 380/37, 380/273, 380/28, 380/29, 380/43
• US Class Current: 380/37
• CPC Class Codes: H04N 21/2347 involving video stream encryption
• CPC Class Codes: H04N 21/26606 for generating or managing entitlement messages, e.g. Entitlement Control Message [ECM] or Entitlement Management Message [EMM] arrangements for conditional access to broadcast information or to broadcast-related services H04H60/14
• CPC Class Codes: H04N 21/4405 involving video stream decryption
• CPC Class Codes: H04N 7/163 by receiver means only
• 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 decrypting an encrypted message comprises first and second decryption devices, the first decryption device having a higher security than the second decryption device. The system further comprises means for dividing the encrypted message into blocks, and means for providing at least the first block of the message to the first decryption device and for providing a plurality of further blocks of this message to the second decryption device. An output of the first decryption device is used as input of the second decryption device. The second decryption device operates according to a block chaining method for decrypting the plurality of further blocks.

Claims

1. A system for decrypting an encrypted message, comprising first and second decryption devices, the first decryption device having a higher security than the second decryption device, means for dividing an encrypted message into blocks, and means for providing at least the first block of a message to the first decryption device and for providing a plurality of the further blocks of this message to the second decryption device, where an output of the first decryption device is used as input of the second decryption device, said second decryption device operating according to a block chaining method for decrypting said plurality of further blocks.

2. The system according to claim 1, wherein said providing means provides each x^th block to the first decryption device.

3. The system according to claim 1, wherein said second decryption device operates according to an error-propagating block chaining method.

4. The system according to claim 1, wherein the first decryption device provides a clear text output.

5. The system according to claim 1, wherein the first decryption device provides a partially decrypted output, wherein the second decryption device first completes the decryption operation.

6. The system according to claim 1 wherein the computing speed of said second decryption device is higher than the computing speed of the first decryption device.

11. The system according to claim 2, wherein said second decryption device operates according to an error-propagating block chaining method.

12. The system according to claim 2, wherein the first decryption device provides a clear text output.

13. The system according to claim 3, wherein the first decryption device provides a clear text output.

14. The system according to claim 11, wherein the first decryption device provides a clear text output.

15. The system according to claim 2, wherein the first decryption device provides a partially decrypted output, wherein the second decryption device first completes the decryption operation.

16. The system according to claim 3, wherein the first decryption device provides a partially decrypted output, wherein the second decryption device first completes the decryption operation.

17. The system according to claim 2, wherein the computing speed of said second decryption device is higher than the computing speed of the first decryption device.

18. The system according to claim 3, wherein the computing speed of said second decryption device is higher than the computing speed of the first decryption device.

19. The system according to claim 4, wherein the computing speed of said second decryption device is higher than the computing speed of the first decryption device.

20. The system according to claim 5, wherein the computing speed of said second decryption device is higher than the computing speed of the first decryption device.

21. The system according to claim 11, wherein the computing speed of said second decryption device is higher than the computing speed of the first decryption device.

22. The system according to claim 12, wherein the computing speed of said second decryption device is higher than the computing speed of the first decryption device.

23. The system according to claim 13, wherein the computing speed of said second decryption device is higher than the computing speed of the first decryption device.

24. The system according to claim 14, wherein the computing speed of said second decryption device is higher than the computing speed of the first decryption device.

25. The system according to claim 15, wherein the computing speed of said second decryption device is higher than the computing speed of the first decryption device.

26. The system according to claim 16, wherein the computing speed of said second decryption device is higher than the computing speed of the first decryption device.

7. A method for distributing data in a system with a number of receivers, comprising the steps of dividing the data into blocks, encrypting at least the first block using a first key and encrypting a plurality of the further blocks according to a block chaining method using the first block as input vector, wherein a second key is used in the block chaining method to encrypt said plurality of further blocks, distributing the encrypted data to the receivers and distributing the first key in an encrypted message to the receivers.

8. The method according to claim 7, comprising the steps of receiving the encrypted data and the first key at a receiver, dividing the encrypted data into blocks, decrypting at least the first block in a first decryption device using the first key, decrypting a plurality of further blocks in a second decryption device, the first decryption device having a higher security than the second decryption device, using an output of the first decryption device as input to the second decryption device and operating the second decryption device according to said block chaining method.

9. The method according to claim 7, wherein the first and second keys are distributed to the receivers in an encrypted message, the encrypted message being decrypted by the first decryption device, wherein the first decryption device forwards the second key and the first block to the second device.

10. The method according to claim 7, wherein the first and each x^th block are encrypted using the first key or decrypted in the first decryption device using the first key, respectively.

27. The method according to claim 8, wherein the first and second keys are distributed to the receivers in an encrypted message, the encrypted message being decrypted by the first decryption device, wherein the first decryption device forwards the second key and the first block to the second device.

28. The method according to claim 8, wherein the first and each x^th block are encrypted using the first key or decrypted in the first decryption device using the first key, respectively.

29. The method according to claim 9, wherein the first and each x^th block are encrypted using the first key or decrypted in the first decryption device using the first key, respectively.