System for broadcasting data signals in a secure manner

• US 6,393,128 B1
• Filed: 08/31/1999
• Issued: 05/21/2002
• Est. Priority Date: 09/01/1998
• Status: Expired due to Term

• Current Assignee: Irdeto B.V. (MultiChoice Group Ltd.)
• Original Assignee: Mindport B. V.
• Inventors: Rix, Simon Paul Ashley, Wajs, Andrew Augustine
• Primary Examiner(s): Decady, Albert
• Assistant Examiner(s): JACK, TODD M
• Application Number:
  US09/387,685
• Time in Patent Office: 994 Days
• Field of Search: 713/185, 713/172, 380/285, 380/284, 380/283, 380/43, 380/259, 380/242, 380/239, 380/205
• US Class Current: 380/283
• CPC Class Codes: H04L 2209/601 Broadcast encryption
• CPC Class Codes: H04L 9/0822 using key encryption key
• CPC Class Codes: H04N 21/4367 Establishing a secure communication between the client and a peripheral device or smart card
• CPC Class Codes: H04N 21/44236 Monitoring of piracy processes or activities protecting computer platforms against harmful, malicious or unexpected behaviour or activities using intrusion detection and counter measures G06F21/566; computer virus detection and handling G06F21/56
• 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 broadcasting data signals in a secure manner comprises means for encrypting the data signals using a first key, means for broadcasting the encrypted data signals to subscribers, means for decrypting the encrypted data signals at each of the subscribers using the first key, and means for encrypting the first key using a second key. The second key is different for each group of subscribers having a common interest in a type of programs. The system further comprises means for broadcasting the encrypted first key to all subscribers and means for decrypting the encrypted first key at each of the subscribers using the second key. The second key is a combination of a key common to all subscribers and a difference key which is unique per type of programs. Means are provided for encrypting the common key and for broadcasting the encrypted common key to all subscribers, the subscribers having means for decrypting the encrypted common key at each of the subscribers.

Claims

1. A system for broadcasting data signals in a secure manner, comprising means for encrypting the data signals using a first key, means for broadcasting the encrypted data signals to subscribers, means for decrypting the encrypted data signals at each of the subscribers using the first key, means for encrypting the first key using a second key, said second key being different for each group of subscribers having a common interest in a type of programs, means for broadcasting the encrypted first key to all subscribers, means for decrypting the encrypted first key at each of the subscribers using the second key, characterized in that said second key is a combination of a key common to all subscribers and a difference key which is unique per type of programs, where means are provided for encrypting the common key and for broadcasting the encrypted common key to all subscribers and means for decrypting the encrypted common key at each of the subscribers.

2. The system according to claim 1, comprising means for changing the common key at a relatively high rate.

3. The system according to claim 1, comprising means for changing the difference key at a relatively low rate, means for encrypting the difference key, means for broadcasting the encrypted key and means for decrypting the encrypted difference key at each of the subscribers.

4. The system according to claim 1, wherein said means for encrypting and decrypting the common key, respectively, include a chain of encrypting and decrypting means, respectively, each next encrypting and decrypting means, operating in a manner common to a smaller number of subscribers.

5. The system according to claim 4, wherein a plurality of the encryption and decryption means of the chain uses a key common to a smaller number of subscribers, wherein the first encrypting and decrypting means of the chain, respectively, uses a card key to encrypt and decrypt, respectively, a basic group key.

6. The system according to claim 3, wherein said basic group key is used as a third key by said encrypting and decrypting means for the difference key, respectively.

9. The system according to claim 2, comprising means for changing the difference key at a relatively low rate, means for encrypting the difference key, means for broadcasting the encrypted key and means for decrypting the encrypted difference key at each of the subscribers.

10. The system according to claim 2, wherein said means for encrypting and decrypting the common key, respectively, include a chain of encrypting and decrypting means, respectively, each next encrypting and decrypting means, operating in a manner common to a smaller number of subscribers.

11. The system according to claim 3, wherein said means for encrypting and decrypting the common key, respectively, include a chain of encrypting and decrypting means, respectively, each next encrypting and decrypting means, operating in a manner common to a smaller number of subscribers.

12. The system according to claim 9, wherein said means for encrypting and decrypting the common key, respectively, include a chain of encrypting and decrypting means, respectively, each next encrypting and decrypting means, operating in a manner common to a smaller number of subscribers.

13. The system according to claim 5, wherein said basic group key is used as a third key by said encrypting and decrypting means for the difference key, respectively.

7. A system for decrypting encrypted data signals in a broadcasting system with a number of subscribers, comprising means for decrypting the encrypted data signals using a first key, means for decrypting the encrypted first key at each of the subscribers using a second key, said second key being different for each group of subscribers having a common interest in a type of programs, characterized in that said second key is a combination of a key common to all subscribers and a difference key which is unique per type of programs, wherein means are provided for decrypting the encrypted common key at each of the subscribers.

8. The system according to claim 7, wherein said means for decrypting the common key includes a chain of decrypting means, each next decrypting means using a key common to a smaller number of subscribers, wherein the first decrypting means of the chain uses a card key to decrypt a group key.

14. A system for broadcasting data signals in a secure manner, the system including:

means for encrypting the data signals using a first key;

means for broadcasting the encrypted data signals to subscribers; and

means for encrypting the first key using a second key, said second key being different for each group of subscribers having a common interest in a type of program, and being a combination of a common key common to all subscribers and a difference key that is unique per type of program, and for broadcasting the encrypted first key to all subscribers, so that the encrypted first key is capable of being decrypted at each of the subscribers using the second key; and

means for encrypting the common key and for broadcasting the encrypted common key to all subscribers for decryption at each of the subscribers.

15. The system according to claim 14, comprising means for changing the common key at a relatively high rate.

16. The system according to claim 14, comprising means for changing the difference key at a relatively low rate, and means for encrypting the difference key.

17. The system according to claim 16, wherein said means for encrypting the common key includes a chain of encrypting means, each next encrypting means of the chain operating in a manner common to a smaller number of subscribers.

18. The system according to claim 17, wherein a plurality of the encryption means of the chain use a key common to a smaller number of subscribers, wherein a first encrypting means of the chain uses a card key to encrypt a basic group key.

19. The system according to claim 18, wherein said basic group key is used as a third key by said encrypting means for the difference key.

20. A system to encrypt data signals, the system including:

a first encryptor to encrypt the data signals using a first key for broadcast to subscribers;

a second encryptor to encrypt the first key using a second key, said second key being different for each group of subscribers having a common interest in a type of program, and being a combination of a common key common to all subscribers and a difference key that is unique per type of program, the first key being encrypted for broadcast to all subscribers so that the encrypted first key is capable of being decrypted at each of the subscribers using the second key; and

a third encryptor to encrypt the common key for broadcast to all subscribers for decryption at each of the subscribers.

21. The system according to claim 20, including a changer to change the common key at a relatively high rate.

22. The system according to claim 20, including a changer to change the difference key at a relatively low rate, and a fourth encryptor to encrypt the difference key.

23. The system according to claim 20, comprising a chain of encryptors, including said third encryptor, each next encryptor of said chain operating in a manner common to a smaller number of subscribers.

24. The system according to claim 23, wherein a plurality of the encryptors of the chain use a key common to a smaller number of subscribers, wherein a primary encryptor of the chain uses a card key to encrypt a basic group key.

25. The system according to claim 24, including a fourth encryptor to encrypt the difference key using said basic group key.

26. A system to decrypt encrypted data signals in a broadcasting system with a number of subscribers, the system including:

a first decryptor to decrypt the encrypted data signals using a first key,

a second decryptor to decrypt an encrypted first key to reveal the first key at each of the subscribers using a second key, said second key being different for each group of subscribers having a common interest in a type of program, characterized in that said second key is a combination of a common key common to all subscribers and a difference key which is unique per type of program; and

a third decryptor to decrypt an encrypted common key to reveal the common key at each of the subscribers.

27. The system according to claim 26, comprising a chain of decryptors, including said third decryptor, each next decryptor of the chain using a key common to a smaller number of subscribers, wherein a primary decryptor of the chain uses a card key to decrypt a group key.

28. The system according to claim 26, wherein said third decryptor to decrypt the encrypted common key includes a chain of decryptors, each next decryptor of the chain operating in a manner common to a smaller number of subscribers.

29. A method to encrypt data signals, the method including:

encrypting the data signals using a first key for broadcast to subscribers;

encrypting the first key using a second key, said second key being different for each group of subscribers having a common interest in a type of program, and being a combination of a common key common to all subscribers and a difference key that is unique per type of program, the first key being encrypted for broadcast to all subscribers so that the encrypted first key is capable of being decrypted at each of the subscribers using the second key; and

encrypting the common key for broadcast to all subscribers and for decryption at each of the subscribers.

30. The method according to claim 29, including changing the common key at a relatively high rate.

31. The method according to claim 29, including changing the difference key at a relatively low rate, and encrypting the difference key.

32. The method according to claim 29, including operating a chain of encryptors to encrypt the common key, each next encryptor of said chain operating in a manner common to a smaller number of subscribers.

33. The method according to claim 32, wherein a plurality of the encryptors of the chain use a key common to a smaller number of subscribers, wherein a primary encryptor of the chain uses a card key to encrypt a basic group key.

34. The method according to claim 33, wherein said basic group key is used as a third key to encrypt the difference key.

35. A method to decrypt encrypted data signals in a broadcasting system with a number of subscribers, the method including:

decrypting the encrypted data signals using a first key,

decrypting an encrypted first key to reveal the first key at each of the subscribers using a second key, said second key being different for each group of subscribers having a common interest in a type of programs, characterized in that said second key is a combination of a common key common to all subscribers and a difference key which is unique per type of programs; and

decrypting an encrypted common key to reveal the common key at each of the subscribers.

36. The method according to claim 35, including operating a chain of decryptors to decrypt the encrypted common key, each next decryptor of the chain using a key common to a smaller number of subscribers, wherein a primary decryptor of the chain uses a card key to decrypt a group key.

37. The method according to claim 35, including operating a chain of decryptors to decrypt the common key, each next decryptor of the chain operating in a manner common to a smaller number of subscribers.