JP2004013763A - Information storage device and information storage method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a system capable of reproducing backup data even when a main storage medium is fatally destroyed and data cannot be read and written. <P>SOLUTION: Contents enciphered by a first title key and a second title key enciphered by the first title key by using a first device key are stored in a main storage medium 19. The contents and the second title key are stored in a storage medium 64 for backup. When moving/deleting the contents from the main storage medium 19, a second device key is formed. A third title key is formed by the second device key and the content of the storage medium 64 for backup is rewritten. In this constitution, the contents can be returned to the original main storage medium from the storage medium for backup and the contents can be reproduced. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an information storage device and an information storage method for encrypting, recording, and viewing content such as audio, images, and videos distributed by broadcasting or the Internet on a storage medium. In particular, the present invention relates to an information storage device and an information storage method for recording a backup of content whose duplication is prohibited.
[0002]
[Prior art]
In recent years, there has been a problem that contents such as audio, images, and videos are copied as digital data and flow over the Internet. To counter this, various copy protection techniques have been considered to prevent digital data from being easily copied.
[0003]
As an example of such a copy protection technique, for example, recording control information such as copy prohibition is added to the content, and only devices that can perform copy control according to the recording control information transmit authentication data for reproducing the content. There are methods such as giving.
[0004]
However, according to the conventional concept of copy protection, when copying of content is prohibited by recording control information, not only illegal copying but also copying for backup is not normally permitted. Can be said to have lost the rights of the user at the same time.
[0005]
In particular, recently, contents distributed via broadcasting or the Internet are stored in individual storage media for use. However, in situations where copying for backup is not allowed, the contents in the storage media may have some cause. If it is destroyed, the user will be severely damaged.
[0006]
Therefore, there is a need for a technology that enables a backup copy even when performing copy protection.
[0007]
As one means for solving this problem, a method of encrypting and recording data in a main storage medium in which contents are stored on a backup storage medium has been considered. In this method, since the data in the main storage medium is encrypted with identification information unique to the main storage medium, the backup data cannot be used unless it is returned to the main storage medium, and only the backup storage medium is illegally used. Can not be used.
[0008]
[Problems to be solved by the invention]
However, in the above-described method, when the main storage medium is catastrophically destroyed and the data cannot be read / written by the main storage medium itself, the backup data cannot be returned to the main storage medium. There is a problem that it becomes impossible to reproduce the data stored in the backup storage medium.
[0009]
Therefore, in the present invention, not only can the content be returned from the backup storage medium to the original main storage medium, but also the main storage medium can be replaced or the backup storage medium itself can be replaced with the main storage medium for use. It is an object to provide an information storage device and an information storage method.
[0010]
[Solution]
In order to solve the above-mentioned problem, in the information storage device of the present invention, means for encrypting content with a first title key and storing the encrypted content in a main storage medium, and encrypting the first title key with a first device key are provided. Means for generating and storing the second title key in the main storage medium, and storing the encrypted content and the encrypted second title key stored in the main storage medium in the backup storage medium. Means for generating a second device key when moving or erasing content stored in the main storage medium, and transferring the encrypted second title key stored in the main storage medium to the first device key. After decrypting with the second device key, the second title key is encrypted with the second device key to generate a third title key, and the encrypted second title key stored in the backup storage medium is replaced with the third title key. Write on key It is characterized in that and means for rewriting replaced.
[0011]
Further, in the information storage method according to the present invention, the content is encrypted with the first title key and stored in the main storage medium, and the first title key is encrypted with the first device key and the second title key is encrypted. Is generated and stored in the main storage medium, and the encrypted content and the encrypted second title key stored in the main storage medium are stored in the backup storage medium. Further, when moving or erasing the content stored in the main storage medium, a second device key is generated, and the encrypted second title key stored in the main storage medium is replaced with the first device key. After that, the third title key is generated by encrypting with the second device key, and the encrypted second title key stored in the backup storage medium is written in the third title key. It is characterized by changing.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0013]
First, the configuration of the information storage device of the present invention will be described with reference to FIG.
[0014]
This information storage device has an input IF 11, a CPU 12, a memory 13, an output IF 14, an EEPROM 15, an encryption / decryption circuit 16, and a storage medium IF 17, and these components are connected via a bus 18. Further, a storage medium 19 such as a magnetic disk is connected to the storage medium IF 17.
[0015]
The CPU 12 manages overall control such as storage processing of contents of the information storage device. The EEPROM 15 holds a device key used when the encryption / decryption circuit 16 encrypts / decrypts data. Is a non-volatile memory.
[0016]
In such a configuration, content such as audio, images, and video distributed via broadcasting or the Internet is externally input via the input IF 11 and sent to the memory 13. The data stored in the memory 13 is encrypted by the encryption / decryption circuit 16 and then stored in the storage medium 19 connected to the storage medium IF 17.
[0017]
When reproducing the content stored in the storage medium 19, the data read from the storage medium 19 is decoded by the encryption / decryption circuit 16, and then output from the output IF 18 for reproduction.
[0018]
Next, a processing procedure when encrypting and decrypting the content by the encryption / decryption circuit 16 will be described with reference to FIG.
[0019]
The plain content C21 is encrypted by the encryption circuit 24 using a block encryption algorithm such as DES, and is recorded on the storage medium 19 as encrypted content Ce210.
[0020]
At this time, the title key Kt23 used for encrypting the content is randomly generated by the title key generating unit 22, and a different title key is used for each content. The title key Kt23 is encrypted by the encryption circuit 27 based on the device key Kd26 randomly generated by the device key generation unit 25, and is recorded on the storage medium as the encrypted title key Kte29.
[0021]
Next, in order to reproduce the encrypted content, first, the encrypted title key Kte29 is read from the storage medium 19 and decrypted with the device key Kd26 to obtain the title key Kt23. Next, the encrypted content Ce210 is read from the storage medium 19, decrypted with the title key Kt23, and the original content C21 is reproduced.
[0022]
As described above, since the device key Kd26 is required for reproducing the content stored in the storage medium 19, the device key Kd26 is stored in the EEPROM 15 so that the value of the device key Kd26 can be retained even when the power is off. It is something to keep.
[0023]
In the content reproduction process associated with the encryption / decryption process, the device key Kd26 is generated and held in the information storage device. For example, even if the storage medium 19 is connected to another device, In this device, the content recorded in the storage medium 19 cannot be reproduced.
[0024]
When a plurality of contents are recorded by the above recording method, the contents of data stored in the storage medium 19 are as shown in FIG.
[0025]
That is, the contents C1e32, C2e33, and C3e34 encrypted with different title keys Kt1, Kt2, and Kt3, and the encrypted title keys Kt1e35, Kt2e36, and Kt3e37 obtained by encrypting the title keys with the same device key Kd are stored in the storage medium 19. It is recorded in.
[0026]
When a new content C4 is additionally recorded in the storage medium 19 as shown in FIG. 3, a new title key Kt4 is generated by the title key generator 22 shown in FIG. The converted content C4e is recorded on the storage medium 19. Furthermore, the title key Kt4 is encrypted with the device key Kd used for encrypting the title keys Kt1, Kt2, and Kt3, and recorded on the storage medium 19 as an encrypted title key Kt4e.
[0027]
Next, a processing method for moving or erasing the content in the storage medium 19 shown in FIG. 3 to another recording / reproducing apparatus (hereinafter, this processing is referred to as moving / erasing) will be described with reference to FIG. .
[0028]
For example, when moving / erasing the content C2e49 stored in the storage medium 19, the content C2e49 and the encrypted title key Kt2e48 are moved / erased from the storage medium 19.
[0029]
At this time, a device key Kd'42 is newly generated by the device key generator 25 shown in FIG. Furthermore, after reading the encrypted title keys Kt1e410 and Kt3e411 remaining in the storage medium 19, the encrypted title keys Kt1e410 and Kt3e411 are decrypted with the old device key Kd41, and then encrypted with the newly generated device key Kd'42. I do.
[0030]
Next, the encrypted title keys Kt1e 'and Kt3e' are overwritten and stored in the storage medium 19. Further, the old device key Kd41 is discarded, and the new device key Kd'42 is stored in the EEPROM 15.
[0031]
By such an operation, data as shown in FIG. 5 is stored in the storage medium 19 after the content is moved / erased.
[0032]
Here, the process of re-encrypting the title key of the content stored in the storage medium 19 with a new device key after moving / erasing the content is referred to as re-encryption of the title key.
[0033]
The reason why the title key is re-encrypted in moving / erasing the content is to prevent illegal copying of the content due to replacement of the storage medium.
[0034]
The replacement of the storage medium means, for example, that the content of the content stored in the storage medium 19 shown in FIG. 3 is copied to another storage medium, and after the content is moved / erased, the content of the content is copied. This is the act of connecting media and restoring the contents that had been moved / erased. At this time, the old encrypted title key can no longer be used by re-encrypting the title key. Therefore, even if the storage medium is replaced, only the old encrypted title key can be moved / erased. You cannot play the content because you do not have it.
[0035]
A method of backing up a storage medium in an information storage device having a function of re-encrypting a title key will be described with reference to FIG.
[0036]
The information storage device includes a main storage medium 19 storing contents and a backup storage medium 64 storing backup data. In order to back up the contents, all the contents stored in the main storage medium 19 or the contents to be backed up and the encrypted title key of the contents are copied to the backup storage medium 64. At this time, because the copied backup storage medium 64 cannot be reproduced even if it is connected to another device, it is not necessary to encrypt the content again.
[0037]
However, when the title key in the main storage medium 19 is re-encrypted, the contents in the backup storage medium 64 cannot be reproduced unless they are returned to the main storage medium 19. Therefore, in this case, the backup itself becomes meaningless when the main storage medium 19 is fatally destroyed as in the related art.
[0038]
In order to solve the problem, in one embodiment of the present invention shown in FIG. 6, when the title key of the main storage medium 19 is re-encrypted, the title key encrypted with the new device key Kd'61 is used. It has a function of automatically overwriting and saving Kte'62 on the backup storage medium 64.
[0039]
Next, a method for backing up content stored in the main storage medium 19 according to an embodiment of the present invention will be described with reference to FIG.
[0040]
First, when a content recording command is issued from the user, a title key used for encrypting the content is generated (S71). Next, the content to be recorded is encrypted (S72) and recorded on the main storage medium 19 (S73). Subsequently, the title key corresponding to the content is encrypted with the device key (S74), and is recorded on the main storage medium 19 (S75).
[0041]
At this time, the user is asked whether or not backup of the content stored in the main storage medium 19 is necessary (S76), and if no backup is necessary, the recording operation ends.
[0042]
If the user instructs that backup is necessary, the encrypted content is copied from the main storage medium 19 to the backup storage medium 64 (S77), and the encrypted title key is subsequently stored in the backup storage medium 64. Copy is performed (S78). Thus, the content stored in the main storage medium 19 is stored as a backup in the backup storage medium 64 together with the encrypted title key.
[0043]
Next, a method of moving / erasing the content stored in the main storage medium 19 will be described with reference to the flowchart shown in FIG.
[0044]
When the user issues a command to move / delete the content stored in the main storage medium 19, the content stored and encrypted from the main storage medium 19 is moved / erased (S81), and then the encrypted content is stored. The moved title key is also moved / erased (s82). At this time, it is confirmed whether or not the content moved / erased from the main storage medium 19 is stored as a backup in the backup storage medium 64 (S83). The encrypted content is deleted from the storage medium 64 (S84), and the encrypted title key stored with the content is also deleted (S85).
[0045]
Next, a new device key is generated to re-encrypt the title key (S86). The encrypted title key is read from the main storage medium 19 (S87) and decrypted with the old device key (S88). The decrypted title key is encrypted with the new device key (S89) and overwritten and stored in the main storage medium 19 (S810). Next, it is determined whether or not this title key is stored in the backup storage medium 64 (S811). If the title key is stored in the backup storage medium 64, the title key is similarly encrypted in the backup storage medium 64. The title key is overwritten and saved (S812). Next, it is determined whether all the encrypted title keys in the main storage medium 19 have been re-encrypted (S813). If the old encrypted title key remains, the encrypted title key is read out again (S87). ), And perform the same processing. Then, when the re-encryption processing of all the encrypted title keys is completed, the new device key is overwritten and saved in the EEPROM 15 and the processing is terminated (S814).
[0046]
In the content moving / erasing method described above, each time one encrypted title key stored in the main storage medium 19 is re-encrypted, the encrypted title key stored in the backup storage medium 64 is re-encrypted. However, in the embodiment of the present invention, all the encrypted title keys stored in the main storage medium 19 are re-encrypted, and then these encrypted title keys are stored in the backup storage. It may be configured to copy to the medium 64.
[0047]
Next, a method for copying all the encrypted title keys to the backup storage medium 64 after re-encrypting all the encrypted title keys stored in the main storage medium 19 will be described with reference to FIG. I do.
[0048]
First, when a user issues a command to move / delete the content stored in the main storage medium 19, the encrypted content stored in the main storage medium 19 is moved / erased (S91), and further encrypted. The stored title key is also moved / erased (S92).
[0049]
At this time, it is checked whether or not the content moved / erased from the main storage medium 19 is stored in the backup storage medium 64 (S93). If the content is stored in the backup storage medium 19, the backup is performed. The encrypted content is deleted from the backup storage medium 64 (S95), and the encrypted title key is also deleted from the backup storage medium 64 (S95).
[0050]
Next, a new device key is generated to re-encrypt the title key (S96). The encrypted title key is read from the main storage medium 19 (S97) and decrypted with the old device key (S98). The decrypted title key is encrypted with the new device key (S99) and overwritten and stored in the main storage medium 19 (S910).
[0051]
Here, it is determined whether all the encrypted title keys stored in the main storage medium 19 have been re-encrypted (S911), and if an old encrypted title key still remains in the main storage medium 19, The reading process of the encrypted title key is continuously executed (S97). Finally, when the re-encryption processing of all the encrypted title keys stored in the main storage medium 19 is completed, the encrypted title keys of the contents stored in the backup storage medium 19 are replaced with the main storage medium. 19 to the backup storage medium 64 (S912). Then, the new device key is overwritten and saved in the EEPROM 15, and the process is completed (S913).
[0052]
As described above, in the information storage device of the present invention, the encrypted content and the encrypted content are stored in the backup storage medium 64 for backing up the content stored in the main storage medium 19. Store the encrypted title key for decryption. Further, the encrypted title key stored in the backup storage medium 64 can be updated.
[0053]
Therefore, in the present invention, not only can the content be returned from the backup storage medium to the original main storage medium, but also the main storage medium can be replaced, or the backup storage medium itself can be replaced with the main storage medium for use. .
[0054]
That is, in the present invention, the content is encrypted with the title key and recorded on the main storage medium, and the title key is encrypted with the device key and recorded on the main storage medium. Further, the encrypted content recorded on the main storage medium and the encrypted title key corresponding to the content are copied to the backup storage medium. Then, a new device key to be used for encryption / decryption when moving or erasing the content from the main storage medium is generated, the encrypted title key recorded on the main storage medium is decrypted with the old device key, and a new device key is generated. The old encrypted title key which has been encrypted in the backup storage medium is rewritten with a new encrypted title key.
[0055]
With this configuration, in the information storage device and the information storage method of the present invention, even when the content stored in the main storage medium is backed up on the backup storage medium, the title is not changed when the content in the main storage medium is moved / erased. Re-encrypting the key with the new device key will render the old title key unusable and its content unplayable. Further, at this time, if another title key stored in the main storage medium is re-encrypted with a new device key, and the re-encrypted title key is stored in the backup storage medium, The title key re-encrypted with the new device key is overwritten on the backup storage medium.
[0056]
Therefore, while preventing illegal copying of the content, when the content of the main storage medium is destroyed, the content for backup can be reproduced by copying the content from the storage medium for backup to the main storage medium.
[0057]
Furthermore, if the main storage medium itself is damaged, the content cannot be played back on the main storage medium, and even if the main storage medium is replaced, the contents can be copied from the backup storage medium to a new main storage medium. It is. Furthermore, when the content cannot be reproduced on the main storage medium, the backup storage medium itself can be connected as the main storage medium, and the backup stored in the backup storage medium can be used. Content restoration is possible.
[0058]
The present invention is not limited to the above-described embodiment, and can be variously modified without departing from the scope of the invention.
[0059]
【The invention's effect】
As described above, according to the present invention, even when the content stored in the main storage medium is backed up to the backup storage medium, the re-encrypted title key is transferred when the content in the main storage medium is moved / erased. Prevents content from being illegally copied by overwriting the backup storage medium, and when the content in the main storage medium is destroyed using the content stored in the backup storage medium, this content is used for backup. Reproduction from a storage medium becomes possible.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration example of an information storage device according to an embodiment of the present invention.
FIG. 2 is a diagram for explaining a processing procedure for encrypting and decrypting content in the information storage device shown in FIG. 1;
3 is a diagram showing contents of data stored in a storage medium in the information storage device shown in FIG.
FIG. 4 is a view for explaining a processing method for moving or erasing the contents of the storage medium shown in FIG. 3;
5 is a diagram showing the contents of data stored in a main storage medium after moving / erasing the contents shown in FIG. 4;
6 is a conceptual diagram showing a method of backing up content stored in a main storage medium shown in FIG.
FIG. 7 is a flowchart showing a method for backing up content stored in a main storage medium shown in FIG. 3;
8 is a flowchart showing an example of a method of moving / erasing content stored in a main storage medium shown in FIG. 3 and a method of storing an encrypted title key in a backup storage medium.
FIG. 9 is a flowchart showing an example of a method of copying an encrypted title key stored in a main storage medium shown in FIG. 3 to a backup storage medium after re-encrypting the encrypted title key.
[Explanation of symbols]
12 ... CPU
15… EEPROM
16: encryption / decryption circuit 19: main storage medium 64: backup storage medium

Claims (9)

Means for encrypting the content with the first title key and storing it in the main storage medium;
Means for encrypting the first title key with a first device key to generate a second title key and storing it in the main storage medium;
Means for storing the encrypted content and the encrypted second title key stored in the main storage medium in a backup storage medium;
Means for generating a second device key when moving or erasing content stored in the main storage medium;
After decrypting the encrypted second title key stored in the main storage medium with the first device key, encrypting the second title key with the second device key to generate a third title key, Rewriting means for rewriting the encrypted second title key stored in the backup storage medium with the third title key;
An information storage device comprising: The rewriting means stores the third title key in the main storage medium, and copies the third title key stored in the storage medium to the backup storage medium by this means. 2. The recording and storage device according to claim 1, further comprising: means for rewriting a first title key stored in the backup storage medium with the third title key. The rewriting means, when storing the third title key in the main storage medium, simultaneously rewrites a first key stored in the backup storage medium with the third title key. The information storage device according to claim 1, further comprising: Encrypting the content with the first title key and storing it in the main storage medium,
Encrypting the first title key with a first device key to generate a second title key, storing the second title key in the main storage medium,
Storing the encrypted content and the encrypted second title key stored in the main storage medium in a backup storage medium;
When moving or erasing the content stored in the main storage medium, a second device key is generated, and the encrypted second title key stored in the main storage medium is transferred to the first device. After decrypting with the key, encrypting with the second device key to generate a third title key,
An information storage method, wherein an encrypted second title key stored in the backup storage medium is rewritten with the third title key. When moving or deleting the content stored in the main storage medium, if the content to be moved or deleted is stored in the backup storage medium, the content stored in the backup storage medium and 5. The information storage method according to claim 4, wherein the second title key corresponding to the content is deleted. When the third title key is generated, the third title key is stored in the main storage medium, and the third title key stored in the main storage medium is copied to the backup storage medium. 5. The method according to claim 4, wherein the stored second title key is rewritten with the third title key. When the third title key is generated, it is stored in the main storage medium, and at the same time, the second title key stored in the backup storage medium is rewritten with the third title key. The information storage method according to claim 4. Copying the encrypted content and the third title key stored in the backup storage medium to the main storage medium when the reproduction of the content stored in the main storage medium becomes impossible. 5. The information storage method according to claim 4, wherein: When the main storage medium itself cannot reproduce data and is replaced with a new main storage medium, the content and the third title key stored in the backup storage medium are copied to the replaced main storage medium. The information storage method according to claim 4, wherein:

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