Method and apparatus for recording information including secret information and method and apparatus for reproduction thereof

• US 20030070082A1
• Filed: 09/09/2002
• Published: 04/10/2003
• Est. Priority Date: 10/10/2001
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Nimura, Hideki, Tanaka, Akio, Kato, Taku, Yamada, Hisashi, Kojima, Tadashi, Kamibayashi, Tooru, Tochikubo, Kouya
• Granted Patent: US 7,372,964 B2
• Time in Patent Office: Days
• US Class Current: 713/193
• 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 20/00246 wherein the key is obtained from a local device, e.g. device key initially stored by the player or by the recorder
• CPC Class Codes: G11B 20/00326 the key being embossed on the record carrier
• CPC Class Codes: G11B 20/00528 wherein each title is encrypted with a separate encryption key for each title, e.g. title key for movie, song or data file
• CPC Class Codes: G11B 20/00536 wherein encrypted content data is subjected to a further, iterated encryption, e.g. interwoven encryption
• CPC Class Codes: G11B 20/00579 said format change concerning the data encoding, e.g., modulation schemes violating run-length constraints, causing excessive DC content, or involving uncommon codewords or sync patterns
• CPC Class Codes: G11B 20/00666 involving a step of erasing or nullifying data, e.g. data being overwritten with a random string
• CPC Class Codes: G11B 20/00753 wherein the usage restriction limits the number of copies that can be made, e.g. CGMS, SCMS, or CCI flags
• CPC Class Codes: G11B 20/00768 wherein copy control information is used, e.g. for indicating whether a content may be copied freely, no more, once, or never, by setting CGMS, SCMS, or CCI flags
• CPC Class Codes: G11B 20/00775 wherein said copy control information is encoded in an encryption mode indicator [EMI]
• CPC Class Codes: G11B 20/14 using self-clocking codes
• CPC Class Codes: G11B 20/1426 conversion to or from block codes or representations thereof
• CPC Class Codes: G11B 2020/10888 the kind of data being the selection criterion
• CPC Class Codes: H04L 9/0822 using key encryption key
• CPC Class Codes: H04L 9/0894 Escrow, recovery or storing of secret information, e.g. secret key escrow or cryptographic key storage

Abstract

An information recording method for recording content information in a recording medium having at least re-readable area, comprising converting, based on a first conversion rule φ1, first information including a first component for obtaining content control information, converting, based on a second conversion rule φ2, second information including a second component for obtaining the first information, and writing the converted first information and the converted second information into the re-recordable area of the recording medium.

Claims

1. An information recording method for recording content information in a recording medium having at least re-readable area, comprising:

converting, based on a first conversion rule φ

1, first information including a first component for obtaining content control information;

converting, based on a second conversion rule φ

2, second information including a second component for obtaining the first information; and

writing the converted first information and the converted second information into the re-recordable area of the recording medium.

2. The method according to claim 1, wherein the first component comprises an encrypted content control information and the second component comprises an encrypted first information.

3. The method according to claim 1, wherein the first conversion rule φ

1 and the second conversion rule φ

2 satisfy φ

<sup>−

1</sup>1(φ

2(X))≠

X.

4. An information reproduction method for reproducing content information from the recording medium in which the information is recorded by the recording method according to claim 1, comprising:

reading the converted first information and the converted second information from the re-recordable area of the recording medium;

inverse-converting, based on a first inverse-conversion rule φ

1<sup>−

1</sup> of the first conversion rule φ

1, the converted first information to obtain original first information; and

inverse-converting, based on a second inverse-conversion rule φ

2<sup>−

1</sup> of the second conversion rule φ

2, the converted second information to obtain original second information.

5. The method according to claim 4, wherein the first conversion rule φ

1 and the second conversion rule φ

2 satisfy φ

<sup>−

1</sup>1(φ

2(X))≠

X.

6. The method according to claim 4, wherein the first component comprises an encrypted content control information and the second component comprises an encrypted first information.

7. An information recording apparatus for recording content information in a recording medium having at least re-readable area, comprising:

a first converter which converts, based on a first conversion rule φ

1, first information including a first component for obtaining content control information;

a second converter which converts, based on a second conversion rule φ

2, second information including a second component for obtaining the first information; and

a writing portion which writes the converted first information and the converted second information into the re-recordable area of the recording medium.

8. The apparatus according to claim 7, wherein

the first converter comprises:

a first encrypting section which encrypts a title key for encrypting the content information to obtain an encrypted title key; and

a second encrypting section which encrypts the encrypted title key based on a random number to obtain a double encrypted title key as the first information;

a converter which converts, based on the first conversion rule φ

1, first information, and

the second converter comprises;

an encrypting section which encrypts the random number based on a medium inherent key to obtain an encrypted random number as the second information; and

a converter which converts, based on the second conversion rule φ

2, second information.

9. An information reproduction apparatus for reproducing content information from the recording medium in which the information is recorded by the recording apparatus according to claim 7, comprising:

a reading portion which reads the converted first information and the converted second information from the re-recordable area of the recording medium;

a first inverse-converter which inverse-converts, based on a first inverse-conversion rule φ

1<sup>−

1</sup> of the first conversion rule φ

1, the converted first information to obtain original first information; and

a second inverse-converter which inverse-converts, based on a second inverse-conversion rule φ

2<sup>−

1</sup> of the second conversion rule φ

2, the converted second information to obtain original second information.

10. The apparatus according to claim 9, wherein

the second information comprises an encrypted random number;

the second inverse-converter decrypts the encrypted random number to obtain the random number;

the first information comprises a double encrypted title key; and

the first inverse-converter comprises a first decrypting portion which decrypts the double encrypted title key based on the random number obtained by the second inverse-converter to obtain an encrypted title key, and a second decrypting portion which decrypts the encrypted title key based on a medium inherent key to obtain an original title key.

11. An information recording method of a medium drive for recording content information in a recording medium having at least re-readable area, comprising:

encrypting in the medium drive, based on a first encryption rule φ

1, first information including the content information;

encrypting in the medium drive, based on a second encryption rule φ

2, second information including a component for obtaining the first information; and

writing the encrypted first information and the encrypted second information into the re-recordable area of the recording medium.

12. The method according to claim 11, wherein the first information comprises a key for encrypting the content information.

13. The method according to claim 11, wherein the first encryption rule φ

1 and the second encryption rule φ

2 satisfy φ

<sup>−

1</sup>1(φ

2(X))≠

X.

14. The method according to claim 11, wherein the second information is supplied from an external device connected to the medium drive and comprises an encrypted title key, the title key encrypting the content information.

15. An information reproduction method for reproducing content information from the recording medium in which the information is recorded by the recording method according to claim 11, comprising:

reading the encrypted first information and the encrypted second information from the re-recordable area of the recording medium;

decrypting in the medium drive, based on a first decryption rule φ

1<sup>−

1</sup> of the first encryption rule φ

1, the encrypted first information to obtain original first information; and

decrypting in the medium drive, based on a second decryption rule φ

2<sup>−

1</sup> of the second encryption rule φ

2, the encrypted second information to obtain original second information.

16. The method according to claim 15, wherein the first information comprises a key encrypting the content information.

17. The method according to claim 15, wherein the first encryption rule φ

1 and the second encryption rule φ

2 satisfy φ

<sup>−

1</sup>1(φ

2(X))≠

X.

18. The method according to claim 15, wherein the second information is supplied to an external device connected to the medium drive and comprises an encrypted title key, the title key encrypting the content information.

19. An information recording apparatus for recording content information in a recording medium having at least re-readable area, comprising:

a first encrypting portion which encrypts, based on a first encryption rule φ

1, first information including the content information;

a second encrypting portion which encrypts, based on a second encryption rule φ

2, second information including a component for obtaining the first information; and

a writing portion which writes the encrypted first information and the encrypted second information into the re-recordable area of the recording medium.

20. The apparatus according to claim 19, wherein the second information is supplied from an external device connected to the medium drive and comprises an encrypted title key, the title key encrypting the content information.

21. An information reproduction apparatus for reproducing information from the recording medium in which the information is recorded by the recording apparatus according to claim 19, comprising:

a reading portion which reads the encrypted first information and the encrypted second information from the re-recordable area of the recording medium;

a first decrypting portion which decrypts, based on a first decryption rule φ

1<sup>−

1</sup> of the first encryption rule φ

l, the encrypted first information to obtain original first information; and

a second decrypting portion which decrypts, based on a second decryption rule φ

2<sup>−

1</sup> of the second encryption rule φ

2, the encrypted second information to obtain original second information.

22. The apparatus according to claim 21, wherein

the second information comprises an encrypted random number;

the second decrypting portion decrypts the encrypted random number to obtain an original random number;

the first information comprises a double encrypted title key; and

the first decrypting portion comprises a first decryptor which decrypts the double encrypted title key based on the random number obtained by the second decrypting portion to obtain an encrypted title key, and a second decryptor which decrypts the encrypted title key based on a medium inherent key to obtain an original title key.