ENCRYPTED CONTENT REPRODUCTION DEVICE, ENCRYPTED CONTENT REPRODUCTION METHOD, PROGRAM, AND RECORDING MEDIUM FOR STORING THE PROGRAM

• US 20090232312A1
• Filed: 11/22/2005
• Published: 09/17/2009
• Est. Priority Date: 11/24/2004
• Status: Abandoned Application

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Ochi, Makoto, Inoue, Shinji, Maeda, Takuji, Fujimura, Kazuya, Suto, Masato, So, Hirokazu, Inoue, Yukiko
• Application Number:
  US11/719,792
• Publication Number:
  US 20090232312A1
• Time in Patent Office: Days
• US Class Current: 380/278
• CPC Class Codes: G11B 20/00086 Circuits for prevention of unauthorised reproduction or copying, e.g. piracy indicating unauthorised use of record carriers in general G11B23/28; scrambling for television signal recording H04N5/913; network architectures or network protocols for network security H04L63/00; cryptographic mechanisms or cryptographic arrangements for secret or secure communication H04L9/00
• CPC Class Codes: G11B 20/0021 involving encryption or decryption of contents recorded on or reproduced from a record carrier
• CPC Class Codes: G11B 20/00253 wherein the key is stored on the record carrier
• CPC Class Codes: G11B 20/00492 wherein content or user data is encrypted
• CPC Class Codes: G11B 20/00543 wherein external data is encrypted, e.g. for secure communication with an external device or for encrypting content on a separate record carrier
• CPC Class Codes: G11B 20/00797 wherein the usage restriction limits the number of times a content can be reproduced, e.g. using playback counters
• CPC Class Codes: G11B 20/0084 wherein the usage restriction can be expressed as a specific time or date
• CPC Class Codes: G11B 2220/61 wherein solid state memory is used for storing A/V content storing computer data in solid state memories G06F
• CPC Class Codes: G11B 2220/65 wherein solid state memory is used for storing indexing information or metadata
• CPC Class Codes: H04L 2209/60 Digital content management, e.g. content distribution
• CPC Class Codes: H04L 9/088 Usage controlling of secret information, e.g. techniques for restricting cryptographic keys to pre-authorized uses, different access levels, validity of crypto-period, different key- or password length, or different strong and weak cryptographic algorithms network architectures or network communication protocols for using time-dependent keys in a packet data network H04L63/068

Abstract

The invention presents an encrypted content playback equipment capable of decryption and playback of an encrypted content by using key information when a key medium storing the key information is not inserted, an encrypted content playback method, a program, and a recording medium for storing the program.

An encrypted content playback equipment 100 obtains key information 1 for a key medium 120, and stores the key information 1 in a provisional-key storage memory 102 as provisional key 1a, and obtains provisional-key usage limitation information 2 for limiting the use of provisional key 1a from the key medium 120. The encrypted content playback equipment 100 judges whether the provisional key 1a is usable or not based on the provisional-key usage limitation information 2, and if usable, plays back an encrypted content 3 by using the provisional key 1a.

Claims

1. An encrypted content playback equipment comprising:

an insertion section, in which a key medium that stores key information for decrypting an encrypted content is inserted, and which obtains the key information;

a storage section that stores provisionally the key information obtained from the key medium as a provisional key;

a provisional-key usage limitation processing section that controls permission of use of the provisional key; and

a decryption section that decrypts the encrypted content by using the provisional key.

2. The encrypted content playback equipment according to claim 1, wherein the provisional-key usage limitation processing section controls permission of use of the provisional key based on a condition specified by provisional-key usage limitation information.

3. The encrypted content playback equipment according to claim 2, wherein the provisional-key usage limitation processing section has a register that stores temporarily the provisional-key usage limitation information.

4. The encrypted content playback equipment according to claim 2, wherein the provisional-key usage limitation information is stored in the storage section.

5. The encrypted content playback equipment according to claim 2, wherein the provisional-key usage limitation information is stored in the key medium together with the key information, and the provisional-key usage limitation processing section obtains the provisional-key usage limitation information from the key medium.

6. The encrypted content playback equipment according to claim 2, wherein when the provisional-key usage limitation processing section judges based on the provisional-key usage limitation information that the provisional key cannot be used, the provisional-key usage limitation processing section deletes the provisional key from the storage section.

7. The encrypted content playback equipment according to claim 2, wherein the provisional-key usage limitation information contains a limit number for limiting the number of times of playback of the content.

8. The encrypted content playback equipment according to claim 2, wherein the provisional-key usage limitation information contains a time limit for limiting playback time of the content.

9. The encrypted content playback equipment according to claim 2, wherein the provisional-key usage limitation information contains a limit distance for limiting a distance capable of playing back the content.

10. The encrypted content playback equipment according to claim 1, wherein the encrypted content is stored in the key medium, and the encrypted content is obtained from the key medium.

11. The encrypted content playback equipment according to claim 1, wherein the encrypted content is stored in a server connected with the encrypted content playback equipment through a network, and the encrypted content playback equipment obtains the encrypted content from the server.

12. The encrypted content playback equipment according to claim 1, wherein the key medium stores the encrypted key information in a user'"'"'s area being read or written regardless of result of mutual authentication, and stores a decrypting key for decrypting the encrypted key information in a protected area being read or written only when mutual authentication is successful, when the key medium is inserted in the insertion section, the storage section stores the encrypted key information as a provisional key and also stores the decrypting key, and the decryption section first decrypts the encrypted provisional key by using the decrypting key, and then decrypts the encrypted content by using the decrypted provisional key.

13. The encrypted content playback equipment according to claim 2, wherein the provisional-key usage limitation information is contained in the encrypted content, the provisional-key usage limitation processing section obtains the provisional-key usage limitation information from the encrypted content being decrypted by the decryption section, and continues decrypting of the encrypted content when the provisional key is judged to be usable, or stops decrypting of the encrypted content when the provisional key is judged to be not usable, based on provisional-key usage limitation information.

14. An encrypted content playback method comprising the steps of:

obtaining key information from a key medium having the key information for decrypting an encrypted content and storing the key information as a provisional key;

controlling permission for use of the provisional key; and

decrypting the encrypted content by using the provisional key.

15. The encrypted content playback method according to claim 14, wherein at the controlling step, permission for use of the provisional key is controlled based on the condition specified by provisional-key usage limitation information.

16. The encrypted content playback method according to claim 15, wherein the provisional-key usage limitation information is stored in the key medium together with the key information.

17. The encrypted content playback according to claim 15, further comprising a step of deleting the provisional key when it is judged based on the provisional-key usage limitation information that the provisional key cannot be used.

18. The encrypted content playback method according to claim 15, wherein the provisional-key usage limitation information contains a limit number for limiting the number of times of playback of the encrypted content.

19. The encrypted content playback method according to claim 15, wherein the provisional-key usage limitation information contains a time limit for limiting playback time of the content.

20. The encrypted content playback method according to claim 15, wherein the provisional-key usage limitation information contains a limit distance for limiting a distance capable of playing back the content.

21. The encrypted content playback method according to claim 14, wherein the key information is encrypted and stored in a user'"'"'s area being read or written regardless of result of mutual authentication by the key medium, and a decrypting key for decrypting the encrypted key information is stored in a protected area being read or written only when mutual authentication by the key medium is successful,

at the step of storing the provisional key, the encrypted key information is stored as a provisional key and the decrypting key is stored, and

at the step of decrypting the encrypted content, the encrypted provisional key is first decrypted by using the decrypting key, and then the encrypted content is decrypted by using the decrypted provisional key.

22. The encrypted content playback method according to claim 15, wherein the provisional-key usage limitation information is contained in the encrypted content, and

at the step of controlling permission for use of the provisional key, the provisional-key usage limitation information is obtained from within the encrypted content being decrypted at the step of decrypting the encrypted content, and

decrypting of the encrypted content is continued when the provisional key is judged to be usable, or decrypting of the encrypted content is stopped when the provisional key is judged to be not usable, based on the provisional-key usage limitation information.

23. A program for causing a computer to execute the steps of:

obtaining key information from a key medium having the key information for decrypting an encrypted content and storing the key information as a provisional key;

controlling permission for use of the provisional key; and

decrypting the encrypted content by using the provisional key.

24. The program according to claim 23, wherein at the controlling step, permission for use of the provisional key is controlled based on the condition specified by provisional-key usage limitation information.

25. The program according to claim 24, wherein the provisional-key usage limitation information is stored in the key medium together with the key information.

26. The program according to claim 24, further comprising a step of deleting the provisional key when it is judged based on provisional-key usage limitation information that the provisional key cannot be used.

27. The program according to claim 24, wherein the provisional-key usage limitation information contains a limit number for limiting the number of times of playback of the content.

28. The program according to claim 24, wherein the provisional-key usage limitation information contains a time limit for limiting playback time of the encrypted content.

29. The program according to claim 24, wherein the provisional-key usage limitation information contains a limit distance for limiting a distance capable of playing back the content.

30. The program according to claim 23, wherein the key information is encrypted and stored in a user'"'"'s area being read or written regardless of result of mutual authentication by the key medium, and a decrypting key for decrypting the encrypted key information is stored in a protected area being read or written only when mutual authentication by the key medium is successful,

at the step of storing the provisional key, the encrypted key information is stored as a provisional key and the decrypting key is stored, and

at the step of decrypting the encrypted content, the encrypted provisional key is first decrypted by using the decrypting key, and then the encrypted content is decrypted by using the decrypted provisional key.

31. The program according to claim 24, wherein the provisional-key usage limitation information is contained in the encrypted content, and

at the step of controlling permission for use of the provisional key, the provisional-key usage limitation information is obtained from within the encrypted content being decrypted at the step of decrypting the encrypted content, and

decrypting of the encrypted content is continued when the provisional key is judged to be usable, or decrypting of the encrypted content is stopped when the provisional key is judged to be not usable, based on provisional-key usage limitation information.

32. A recording medium that stores a program of claim 23.