Content transmission apparatus, content reception apparatus, content transmission program, and content reception program

• US 20040052379A1
• Filed: 05/29/2003
• Published: 03/18/2004
• Est. Priority Date: 10/03/2001
• Status: Active Grant

• Current Assignee: Nippon Hoso Kyokai
• Original Assignee: Nippon Hoso Kyokai
• Inventors: Uehara, Toshihiro, Kurioka, Tatsuya, Nishimoto, Yusei, Namba, Seiichi
• Granted Patent: US 7,567,674 B2
• Time in Patent Office: Days
• US Class Current: 380/281
• CPC Class Codes: H04N 21/2347 involving video stream encryption
• CPC Class Codes: H04N 21/4405 involving video stream decryption
• CPC Class Codes: H04N 21/4408 involving video stream encryption, e.g. re-encrypting a decrypted video stream for redistribution in a home network
• CPC Class Codes: H04N 21/835 Generation of protective data, e.g. certificates protecting software against unauthorised usage in a vending or licensing environment G06F21/10
• 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 content transmission method, a content reception method, an apparatus and a computer program using same, that improve the efficiency of descrambling a scrambled content, make the management of cryptography keys for descrambling easy, and protect the copyright of contents, are provided. A content transmission apparatus 3 that encrypts and transmits contents and a content reception apparatus 5 that receives the encrypted contents are provided. The content transmission apparatus 3 includes a content scrambling unit 7 that encrypts contents using a scrambling key Ks, a content key Kc, a work key Kw, a master key Km, and a multiplexing unit 9 that transmits multiplexed contents. The content reception apparatus 5 includes a separating unit 13 that receives and separates the multiplexed encrypted content, and a content descrambling unit 15 that obtains the contents by descrambling encrypted information separated by the separating unit 13.

Claims

1. A content transmission apparatus that encrypts and transmits contents of digital broadcasting, comprising:

a storing means for storing a scrambling key that changes as time passes, a content key provided to each content, and a master key provided commonly to a receiver side;

a content encrypting means for generating encrypted contents by encrypting said contents using said scrambling key;

a related information encrypting means for generating encrypted related information by encrypting related information related to said contents including at least said scrambling key using said content key;

a content key related information encrypting means for generating encrypted content key related information by encrypting related information related to said content key including at least said content key using said master key;

a multiplexing means for generating multiplexed encrypted content by multiplexing said encrypted content, said encrypted related information, and said encrypted content key related information; and

a multiplexed encrypted content transmitting means for transmitting multiplexed encrypted content multiplexed by said multiplexing means.

6. The content transmission apparatus as claimed in any one of claims 1 through 5, further comprising a content key related information use designating means that, in a case in which a storage medium handling means is provided at a receiver side, and said encrypted content is stored therein and said encrypted content is reproduced, if an encrypted content key related information corresponding to said encrypted content is already transmitted, does not use said encrypted content key related information and designates stored content key related information.

2. A content transmission apparatus that encrypts and transmits contents of digital broadcasting, comprising:

a storing means for storing therein a scrambling key that changes as time passes, a content key provided to each content, a work key retained for a time period longer than a duration of said contents, and a master key provided commonly to a receiver side;

a content encrypting means for encrypting said contents using said scrambling key, thereby to obtain encrypted contents;

a related information encrypting means for encrypting related information related to said contents including at least said scrambling key using said content key, thereby to obtain encrypted related information;

a content key related information encrypting means for encrypting related information related to said content key including at least said content key using said work key, thereby to obtain encrypted content key related information;

a work key related information encrypting means for encrypting related information related to said work key including at least said work key using said master key thereby to obtain encrypted work key related information;

a multiplexing means for multiplexing said encrypted contents, said encrypted related information, said encrypted content key related information, and said encrypted work key related information, thereby to obtain multiplexed encrypted contents; and

a multiplexed encrypted content transmitting means for transmitting said multiplexed encrypted contents multiplexed by said multiplexing means.

4. The content transmission apparatus as claimed in claim 2 or 3, wherein, in a case in which said receiver side is provided with a security module for storing encrypted content key related information and is inaccessible from an exterior, a plurality of security modules are provided correspondingly to a reception apparatus of said receiver side, the plurality of security modules are grouped into a plurality of groups, and a plurality of work keys are provided each corresponding to one of the plurality of groups of the security modules.

5. The content transmission apparatus as claimed in claim 4, further comprising a content key related information storage designating means that, when said encrypted content key related information is decrypted into content key related information at the receiver side, and said content key related information is stored as is, or after being re-encrypted, in a case in which a reception apparatus of said receiver side is provided with at least one of a storing means or a storage medium handling means that handles a storage medium, designates one of said security module, said storing means, and said storage medium to retain said content key related information.

7. The content transmission apparatus as claimed in any one of claims 4 through 6, further comprising an intrinsic key setting related information encrypting means for encrypting a plurality of intrinsic keys into encrypted intrinsic key setting related information;

wherein the plurality of intrinsic keys for encrypting information outputted from said security module are set in said security module.

8. The content transmission apparatus as claimed in claim 7, wherein at least one of the plurality of intrinsic keys is set common to another security module.

3. A content transmission apparatus that encrypts and transmits contents of digital broadcasting, comprising:

a storing means for storing a scrambling key that changes as time passes, a content key provided to each content, a work key retained for a time period longer than a duration of said contents, and a master key provided commonly to a receiver side;

a content encrypting means for encrypting said contents using said scrambling key, thereby to obtain encrypted contents;

a related information encrypting means for encrypting related information related to said contents including at least said scrambling key, thereby to obtain encrypted related information;

a content key related information encrypting means for encrypting related information related to said content key including at least said content key using said work key, thereby to obtain encrypted content key related information;

a work key related information encrypting means for encrypting related information related to said work key including at least said work key using said master key, thereby to obtain encrypted work key related information;

a multiplexing means for multiplexing said encrypted content, said encrypted related information, and said encrypted work key related information, thereby to obtain multiplexed encrypted contents;

a multiplexed encrypted content transmitting means for transmitting said multiplexed encrypted contents multiplexed by said multiplexing means; and

an encrypted content key related information transmitting means for transmitting said encrypted content key related information in at least one of manners in which said encrypted content key related information is transmitted repeatedly in a predetermined interval for a predetermined time period after said multiplexed encrypted content starts to be transmitted, is transmitted repeatedly in a predetermined interval from a predetermined time period before said multiplexed encrypted content starts to be transmitted to a predetermined time period after said multiplexed encrypted content is finished being transmitted, or is transmitted, if said receiver side does not receive said encrypted content key related information, in response to a request from said receiver side or via a communication channel network.

9. A content reception apparatus that receives encrypted contents of digital broadcasting, encrypted at a transmitter side, comprising:

a multiplexed encrypted content receiving means for receiving a multiplexed encrypted content, wherein said transmitter side multiplexes a content encrypted using a scrambling key changing as time passes, a related information related to the content including at least the scrambling key encrypted using a content key provided to each content, a content key related information related to the content key including at least the content key encrypted using a master key provided commonly to the transmitter side, into the multiplexed encrypted content, and transmits the multiplexed encrypted content to the multiplexed encrypted content receiving means;

a multiplexed encrypted content separating means for separating the multiplexed encrypted content received by the multiplexed encrypted content receiving means, into the encrypted content, the encrypted related information, and the encrypted content key related information;

a multiplexed encrypted content decrypting means for obtaining the content by decrypting the encrypted content key related information using the master key, the scrambling key included in the encrypted related information using the decrypted content key, and the encrypted content using the decrypted scrambling key.

10. A content reception apparatus that receives encrypted contents of digital broadcasting, encrypted at a transmitter side, comprising:

a multiplexed encrypted content receiving means for receiving a multiplexed encrypted content, wherein said transmitter side multiplexes a content encrypted using the scrambling key changing as time passes, a related information related to the content including at least the scrambling key encrypted using a content key provided to each content, a content key related information including at least the content key encrypted using a work key retained for a time period longer than a duration of the content, the work key related information including at least the work key encrypted using a master key provided commonly to the transmitter side, into the multiplexed encrypted content;

a multiplexed encrypted content separating means for separating the multiplexed encrypted content received by the multiplexed encrypted content receiving means, into the encrypted content, the encrypted related information, the encrypted content key related information, and the encrypted work key related information;

a multiplexed encrypted content decrypting means for obtaining the content by decrypting the encrypted work key related information using the master key, the content key included in the encrypted content key related information using the decrypted work key, the scrambling key included in the encrypted related information using the decrypted content key, and the encrypted content using the decrypted scrambling key.

11. The content reception apparatus as claimed in claims 9 or 10, further comprising an encrypted content key related information requesting means that, if the encrypted content key related information is not received, requests the encrypted content key related information from the transmitter side.

12. The content reception apparatus as claimed in any one of claims 9 through 11, further comprising:

a security module inaccessible from an exterior in which the master key is set; and

a content key related information storing means for storing decrypted content key related information and a content identifier related to the content key related information for identifying the content.

13. The content reception apparatus as claimed in any one of claims 9 through 11, further comprising:

a security module inaccessible from an exterior in which the master key and intrinsic keys for encrypting information to be output are set; and

a content key related information storing means for storing decrypted content key related information and a content identifier related to the content key related information for identifying the content.

14. The content reception apparatus as claimed in claim 13, wherein at least one of the intrinsic keys is set commonly to another security module.

15. The content reception apparatus as claimed in claim 13 or 14, further comprising:

an encrypted intrinsic key setting related information receiving means for receiving encrypted intrinsic key setting related information, wherein the transmitter side encrypts a plurality of intrinsic keys into the encrypted intrinsic key setting related information; and

an encrypted intrinsic key setting related information decrypting means for decrypting, using the master key, the encrypted intrinsic key setting related information received by the encrypted intrinsic key setting related information receiving means.

16. The content reception apparatus as claimed in any one of claims 12 through 15, further comprising a content key related information deleting means that, in a case in which the decrypted content key related information requires more memory capacity than that which the security module can store, deletes the decrypted content key related information based on a time at which said decrypted content key related information is stored and information set by the transmitter side or the receiver side.

17. The content reception apparatus as claimed in any one of claims 12 through 16, further comprising a content key related information output storing means for outputting and storing the decrypted content key related information stored in the security module.

18. The content reception apparatus as claimed in claim 17, further comprising a content key related information deleting means that, in a case in which the decrypted content key related information requires more memory capacity than that which the storing means can store, deletes the decrypted content key related information based on a time at which said decrypted content key related information is stored and information set by the transmitter side or the receiver side.

19. The content reception apparatus as claimed in any one of claims 12 through 18, further comprising a content key related information re-encryption storing means for encrypting the decrypted content key related information stored in the security module using the master key, and outputting and storing the encrypted content key related information as re-encrypted content key related information.

20. The content reception apparatus as claimed in claim 19, further comprising a re-encrypted content key related information deleting means that, in a case in which the re-encrypted content key related information and a content identifier for identifying a content require more memory capacity than that which the storing means can store, deletes the re-encrypted content key related information based on a time at which the re-encrypted content key related information is stored or information set by the transmitter side or the receiver side.

21. The content reception apparatus as claimed in any one of claims 12 through 16, further comprising a content key related information intrinsic encryption storing means for encrypting, using said intrinsic keys, the decrypted content key related information stored in the security module into an intrinsic encrypted content key related information, and outputting and storing the intrinsic encrypted content key related information.

22. The content reception apparatus as claimed in claim 21, further comprising an intrinsic encrypted content key related information deleting means that, in a case in which the intrinsic encrypted content key related information and a content identifier for identifying a content require more memory capacity than that which the storing means can store, deletes the intrinsic encrypted content key related information based on a time at which the intrinsic encrypted content key related information is stored or information set by the transmitter side or the receiver side.

23. The content reception apparatus as claimed in any one of claims 9 through 15, further comprising a storage medium handling means for storing re-encrypted content key related information with a corresponding encrypted content;

wherein the decrypted content key related information is re-encrypted into the re-encrypted content key related information using the master key.

24. The content reception apparatus as claimed in any one of claims 13 through 15, further comprising a storage medium handling means for storing intrinsic encrypted content key related information with a corresponding encrypted content;

wherein the decrypted content key related information is re-encrypted into the re-encrypted content key related information using the intrinsic keys.

25. The content reception apparatus as claimed in any one of claims 12 through 16, claim 19, claim 20, and claim 23, further comprising:

an encrypted content storing means provided with a storing means and a storage medium handling means, that stores, in a storage medium handled by the storage medium handling means, encrypted content encrypted using the scrambling key and encryption related information related to the content including a content identifier for identifying the encrypted content;

a related information inputting means, wherein in a case in which, when the encrypted content stored in the storage medium is reproduced, the re-encrypted content key related information corresponding to the encrypted content is stored in at least one of the storing means and the storage medium, the related information inputting means reads and inputs, in the security module, the re-encrypted content related information from the storing means or the storage medium, and inputs the encrypted related information;

a scrambling key outputting means that obtains the content key by decrypting the re-encrypted content key related information using the master key, obtains the scrambling key by decrypting the encrypted related information using the content key, and outputs the scrambling key; and

an encrypted content decrypting means for decrypting the encrypted content stored in the storage medium using the scrambling key outputted by the scrambling key outputting means.

26. The content reception apparatus as claimed in any one of claims 13 through 16, claim 19, claim 21, claim 22, and claim 24, further comprising:

an encrypted content storing means provided with a storing means and a storage medium handling means, that stores, in a storage medium handled by the storage medium handling means, encrypted content encrypted using the scrambling key and encryption related information related to the content including a content identifier for identifying the encrypted content;

a related information inputting means, wherein in a case in which, when the encrypted content stored in the storage medium is reproduced, the intrinsic encrypted content key related information corresponding to the encrypted content is stored in at least one of the storing means and the storage medium, the related information inputting means reads and inputs, in the security module, the intrinsic encrypted content related information from the storing means or the storage medium, and inputs the encrypted related information;

a scrambling key outputting means that obtains the content key by decrypting the intrinsic encrypted content key related information using the intrinsic key, obtains the scrambling key by decrypting the encrypted related information using the content key, and outputs the scrambling key; and

an encrypted content decrypting means for decrypting the encrypted content stored in the storage medium using the scrambling key outputted by the scrambling key outputting means.

27. The content reception apparatus as claimed in any one of claims 9 through 26, further comprising a content key un-storing means that, in a case in which the encrypted content is not stored during transmission of the encrypted content, does not store content key corresponding to the encrypted content.

28. The content reception apparatus as claimed in any one of claims 9 through 27, further comprising a content key switching means for switching the content key based on a time at which a content corresponding to the encrypted related information starts to be transmitted and a time at which the content is finished being transmitted.

29. A content transmission program that causes a content transmission apparatus that encrypts and transmits a content of digital broadcasting to operate as:

a storing means for storing therein a scrambling key that changes as time passes, a content key provided to each content, a work key retained for a time period longer than a duration of said contents, and a master key provided commonly to a receiver side;

a content encrypting means for encrypting said contents using said scrambling key, thereby to obtain encrypted contents;

a related information encrypting means for encrypting related information related to said contents including at least said scrambling key using said content key, thereby to obtain encrypted related information;

a content key related information encrypting means for encrypting related information related to said content key including at least said content key using said work key, thereby to obtain encrypted content key related information;

a work key related information encrypting means for encrypting related information related to said work key including at least said work key using said master key thereby to obtain encrypted work key related information;

a multiplexing means for multiplexing said encrypted contents, said encrypted related information, said encrypted content key related information, and said encrypted work key related information, thereby to obtain multiplexed encrypted contents; and

a multiplexed encrypted content transmitting means for transmitting said multiplexed encrypted contents multiplexed by said multiplexing means.

30. A content reception program that causes a content reception apparatus that receives a content of digital broadcasting encrypted at a transmitter side to operate as:

a storing means that stores the master key commonly provided to the transmitter side;

a multiplexed encrypted content receiving means for receiving a multiplexed encrypted content, wherein said transmitter side multiplexes a content encrypted using the scrambling key changing as time passes, a related information related to the content including at least the scrambling key encrypted using a content key provided to each content, a content key related information including at least the content key encrypted using a work key retained for a time period longer than a duration of the content, a work key related information including at least the work key encrypted using a master key provided commonly to the transmitter side, into the multiplexed encrypted content;

a multiplexed encrypted content separating means for separating the multiplexed encrypted content received by the multiplexed encrypted content receiving means, into the encrypted content, the encrypted related information, the encrypted content key related information, and the encrypted work key related information;

a multiplexed encrypted content decrypting means for obtaining the content by decrypting the encrypted work key related information using the master key, the content key included in the encrypted content key related information using the decrypted work key, the scrambling key included in the encrypted related information using the decrypted content key, and the encrypted content using the decrypted scrambling key.