JP2012109743A - Content storage device and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a content storage device and a program which can perform proper backup of a content even if the content is copy-controlled.SOLUTION: A content management database 191 stored in a built-in HDD 19 is copied in a flash memory 12 as a content management database 121. Even if the built-in HDD 19 malfunctions and the content management database 191 cannot be read out, by referring to the copied content management database 121, each content can be reproduced.

Description

  The present invention relates to a content storage device and a program, and more particularly to a technique related to a copyrighted content storage process.

  In recent years, the distribution of digital contents has become widespread, and it has become possible to store the distributed contents on a storage medium such as an HDD. However, since digital contents can be easily copied, a device for storing the digital contents is obliged to be equipped with a copyright protection function (see Patent Document 1). As for the copyright protection function, it is general that only the first storage is possible and the content cannot be copied (copy once), or can be copied up to nine times (dubbing 10).

  Content is often stored in a large capacity HDD. However, there is a possibility that the HDD may fail because mechanical parts are used. If the HDD fails, the stored content is lost, so it is desired to perform backup.

  However, copy-once content cannot be backed up to another device, and even dubbing 10 content cannot be backed up after 9 copies.

  Therefore, the apparatus of Patent Document 1 stores encrypted content and usage control information (information indicating the presence of content and a key for decrypting the content) and backing up the content. In addition, by adopting a configuration in which the usage control information is not changed, it is possible to restore the backed up content when the content is lost, but not to reproduce it on other devices.

JP 2006-195973 A

  However, even if the apparatus of Patent Document 1 can back up the content, if the above usage control information is lost, the content cannot be reproduced after all.

  An object of the present invention is to provide a content storage device and a program capable of appropriately backing up even content whose copy is restricted.

  The content storage device according to the present invention includes a first storage unit and a second storage unit that store encrypted content, and a copy of the content stored in the first storage unit to the second storage unit. Content copy means. And the content management means which manages a content based on content management information, The content management information copy means which copies the said content management information is provided.

  Here, the content management means manages content using the content management information copied by the content management information copying means when the content management information cannot be used.

  In this way, by duplicating the content management information, the medium in which the content management information (main) is stored fails, or the content management information (main) cannot be used due to some error or alteration. However, each content can be appropriately read by referring to the copied content management information (sub).

  For example, in the case where the content management information (main) is stored in the first storage means (for example, the built-in HDD), even if the built-in HDD fails and the content management information (main) is lost together with the content, Since the copied content management information (sub) is left, the content backed up in the second storage means (for example, external HDD) is reproduced using this content management information (sub). It becomes possible.

  The content storage device of the present invention further includes an erasure processing unit that outputs and erases the content, and the content management unit outputs information indicating that the content has been output after the content is output and erased. And the erasure processing means stores the information indicating that the output has been recorded in the content management information and the content corresponding to the information indicating the output has been stored in the own device. The content is erased.

  In this way, when a certain content is output and erased, that is, moved out, information indicating that it has been moved out is recorded, and then it is determined that the corresponding content is still stored in the own device. In this case, by deleting the corresponding content, it is possible to prevent the backed up content from being left in the external HDD. For example, even when there are multiple external HDDs and there are many backed up contents, they are automatically deleted when the external HDD is connected to the device, so many backed up contents remain. It is useful from the viewpoint of copyright protection without increasing unnecessary data.

  In addition, an aspect including a third storage unit that stores content management information as a hash by one-way function processing is also possible. The one-way function processing is easy to convert from content management information to hash, but conversely cannot convert from hash to content management information. In this way, if the hash of the content management information is stored, the hash generated from the content management information and the stored hash are collated to check whether the content management information is valid (unauthorized rewriting). Or whether it has been broken due to an error or the like).

  The copied content management information (sub) is preferably stored separately as a hash (sub). When writing the hash of the main content management information into the third storage means, if some error occurs and the hash is not appropriate, the hash that is stored with the hash generated from the content management information (main) later Even if (main) cannot be collated, the hash generated from the content management information (sub) and the stored hash (sub) can be collated, thereby improving fault tolerance. Become.

  The third storage means is preferably a secure memory that can be read and written only by an authenticated device, for example, so that the hash is not rewritten. The secure memory has a limited capacity as compared with the HDD and the flash memory. However, in the present invention, since the hash is stored, the required capacity is very small.

  The content management information (sub) is preferably stored in a fourth storage unit (for example, a built-in flash memory). By storing the information in a storage medium different from the HDD such as a flash memory, it is possible to further reduce the risk of losing the content management information. Although the flash memory has a relatively smaller capacity than the HDD, the content management information is similar to text data and is much smaller than the data amount of the content itself. Therefore, since the amount of content management information does not increase so much even if the amount of content increases, wear leveling (a process of distributing rewrites to elements in the flash memory without reducing the capacity of the flash memory) ) Is low, and the possibility that the copied content management information (sub) will be lost is extremely low.

  According to the present invention, it is possible to appropriately back up even content whose copy is restricted.

It is a block diagram which shows the main structures of information processing apparatus. It is a functional block diagram of an information processor. It is a flowchart which shows the operation | movement at the time of a move-in. It is a conceptual diagram which shows the content management state before moving in content D. It is a conceptual diagram which shows the content management state after moving in the content D. FIG. It is a flowchart which shows the operation | movement at the time of reproduction | regeneration. It is a conceptual diagram which shows the flowchart which shows the operation | movement at the time of backup, and the content management state after backup. It is a flowchart which shows the operation | movement at the time of a move out. It is a conceptual diagram which shows the content management state after moving out content D. FIG. It is a flowchart which shows the operation | movement at the time of deleting the content already moved out.

  FIG. 1A is a schematic diagram showing a configuration of a content processing system, and FIG. 1B is a block diagram showing a main configuration of an information processing apparatus (NAS: Network Attached Storage) of the present invention. The NAS 1 is connected to the HDD recorder 2 via a network 3 such as a LAN.

  The HDD recorder 2 receives content via broadcast waves (terrestrial digital broadcast, CS broadcast, BS broadcast, etc.) and the Internet, and stores it in a built-in HDD (not shown). The HDD recorder 2 outputs (move out) the content via the network 3, and the NAS 1 inputs the content from the HDD recorder 2 and stores (move in) it. Or, conversely, the NAS 1 outputs (move out) the content via the network 3, and the HDD recorder 2 inputs the content from the NAS 1 and stores (move in) it. Further, the NAS 1 outputs the content requested from the playback device connected via the network 3. The playback device includes the HDD recorder 2 shown in FIG. 1A and other devices such as a personal computer.

  As described above, the NAS 1 has a function of a content server that inputs and accumulates content from other devices and outputs the content in response to requests from other playback devices.

  In the figure, the HDD recorder is shown as a device for moving out or moving in the content. However, other devices (television, tuner, personal computer, other NAS, etc.) may of course be used.

  In this embodiment, an example in which content is input / output via a network is shown, but an aspect in which content is input / output via another communication line (USB, IEEE 1394, etc.) is also possible.

  As shown in FIG. 1B, the NAS 1 includes various components connected via a bus 11, and includes a flash memory (NAND) 12, a RAM 13, a control unit 14, a secure memory 15, an encryption processing unit 16, and a network. An interface 17, an HDD interface 18, and a built-in HDD 19 are provided. Further, an external HDD (cartridge HDD in the example in the figure) 20 is connected to the NAS 1 via the HDD interface 18.

  The control unit 14 develops basic software and application software stored in the built-in HDD 19 in the RAM 13 and performs various operations. In the present embodiment, as shown in the functional block diagram of FIG. 2, content management processing, DTCP-IP encryption / decryption processing, local encryption processing, UI processing, and one-way function processing are performed. Various processes will be described in detail later.

  In addition to the software described above, the built-in HDD 19 stores and stores the moved-in content as well as the content management database (content management information) 191 that is information for managing the content, as shown in FIG. The content management database (main) 191 is copied to the flash memory 12 and stored as the content management database (sub) 121. The content management database 191 is referred to by the control unit 14 at the time of content reproduction, move-out, or at an arbitrary timing. The contents of the content management database will be described later in detail.

  The cartridge HDD 20 is a portable HDD that can be easily inserted and removed, and, like the built-in HDD 19, stores and stores the moved-in content. In the present embodiment, an example of the cartridge HDD 20 dedicated to the NAS 1 is shown. However, the cartridge HDD 20 may conform to a standard such as iVDR, or may be a rewritable medium such as a DVD, a Blu-ray disc, or an SD memory card. . In the NAS 1 of the present embodiment, the content stored in the internal HDD 19 can be copied and stored in the cartridge HDD 20 as a backup. Conversely, the content stored in the cartridge HDD 20 can be copied to the built-in HDD 19. However, as will be described later, the content stored in the cartridge HDD 20 cannot be reproduced by other devices.

  FIG. 3 is a flowchart showing the operation during move-in. This operation is executed when the user operates another device (HDD recorder 2 or personal computer) to give an instruction to move out content to the NAS 1.

  First, the NAS 1 inputs content from the network interface 17 (s11). In the example of FIG. 1A, content is input from the HDD recorder 2 via the network 3. Content input is performed in predetermined data units (packets). At this time, content is transmitted and received in accordance with the DTCP-IP standard. In DTCP-IP, mutual authentication is performed between devices using a certificate issued by DTLA, and encryption / decryption processing (common key encryption method) is performed using a DTLA device key held for each device.

  The control unit 14 decrypts the input content using the DTCP-IP encryption / decryption processing function (s12). In practice, hardware decryption processing is performed by the encryption processing unit 16. The DTLA device key is stored in the secure memory 15 as shown in FIG. The secure memory 15 is a memory that can be read and written only by an authenticated device (for example, the control unit 14 of the own device) that has undergone mutual authentication. Even if the secure memory 15 is taken out by disassembling the NAS 1, Can not read and write. It is not essential to secure the memory itself as a single piece of hardware. Secure memory can be created by making it impossible to read the stored contents, limiting access to specific areas, or encrypting each data. It may be realized. In addition, a mode is also possible in which the secure memory 15 is built in the control unit 14 so as to be inseparable hardware and cannot be physically accessed from the outside. Secure memory has a limited capacity compared to HDD and flash memory. However, as will be described later, since secure memory is a mode for storing a hash, the required capacity is very small. . The control unit 14 reads the DTLA device key from the secure memory 15 and inputs the read DTLA device key and the input content to the encryption processing unit 16 to decrypt the content.

  Thereafter, the control unit 14 re-encrypts the decrypted content using the local encryption processing function and stores it in the internal HDD 19 or the cartridge HDD 20 (s13). The content storage destination (folder) is designated by the user using the UI of another device. When the storage destination is not specified in the UI of another device, the storage destination is stored in a storage destination (folder) set in the NAS 1 in advance. This local cryptographic processing is also actually performed by the cryptographic processing unit 16 as hardware cryptographic processing. The local encryption key is also stored in the secure memory 15, and the control unit 14 reads the local encryption key from the secure memory 15 and inputs the read local encryption key and the decrypted content to the encryption processing unit 16 to encrypt the content. Then save. The local encryption key uses a random value that is unique to each device, and by performing local encryption processing, the content cannot be reproduced on other devices.

  The content input, decryption, and re-encryption processing as described above is repeated until data for one content is received (s14).

  And the control part 14 will update the content of the content management database 191, if all the data of the designated content are received. FIG. 4 is a conceptual diagram showing a content management state in the NAS 1 before moving in a certain content (content D in the example of FIG. 4). FIG. 5 is a conceptual diagram showing a content management state after the content D is moved in.

  As shown in FIG. 4, the content management database 191 describes information on all contents moved into the own apparatus (the built-in HDD 19 and the cartridge HDD 20). As content information, a header for identifying each content, a part of data, and the like are described. The count value is information indicating whether or not the content has been moved out. The content stored in the apparatus without being moved out is counted 1, and the content moved out is counted 0.

  In the example of FIG. 4, content A and content B are stored in the built-in HDD 19 and content C is stored in the cartridge HDD 20. Here, when the content D is moved in, the information of the content D is added to the content management database 191 as shown in FIG.

  Returning to FIG. 3, the control unit 14 generates a hash (main) from the updated content management database 191 using the one-way function processing, and stores it in the secure memory 15 (s16). The one-way function processing is easy to convert from the content management database 191 to the hash (main), but conversely cannot be converted from the hash (main) to the content management database 191. As described above, by storing the hash (main) corresponding to the content management database 191, the hash generated from the content management database 191 each time the content is reproduced and the hash ( The validity of the content management database 191 can be determined.

  Next, the control unit 14 copies the content management database 191 and stores it in the flash memory 12 as the content management database 121 (s17). When the content management database 121 is already stored in the flash memory 12, a process of replacing the content management database 121 with a new copy is performed. Then, the control unit 14 generates a hash (sub) from the content management database 121 using the one-way function process (s18).

  FIG. 6 is a flowchart showing the operation during content reproduction. First, the control unit 14 receives content to be reproduced by the UI processing from the user (s31). In the UI processing, content stored in the NAS 1 (the built-in HDD 19 and the cartridge HDD 20) is displayed on the screen of a display connected to a device that reproduces the content (DTCP-IP compatible device such as the HDD recorder 2 or a personal computer). This is a process of displaying a list and accepting content specification. When the user designates the content displayed on the screen and gives a reproduction instruction, the reproduction of the content is accepted.

  Using the content management function, the control unit 14 newly generates a hash from the content management database 191 and performs a process of collating with the hash (main) stored in the secure memory 15 (s32). If collation is possible (s33), the designated content is decrypted using the local encryption key stored in the secure memory 15 (s34). Then, re-encryption is performed by DTCP-IP encryption / decryption processing using the DTLA device key stored in the secure memory 15 (s35). These decryption processing and re-encryption processing are also actually performed as hardware processing in the encryption processing section 16. Then, the control unit 14 outputs the encrypted content (s36).

  On the other hand, if the control unit 14 determines in s33 that collation is not possible, the control unit 14 newly generates a hash from the content management database 121 and performs a process of collating with the hash (sub) stored in the secure memory 15 (s37). ). When collation is completed (s38), the control unit 14 performs content decryption (s34), re-encryption (s35), and output processing (s36). At this time, the hash (main) may be restored by copying the hash (sub) to the hash (main) on the assumption that some error has occurred during storage of the hash (main). If the hash (sub) is copied to the hash (main) and repaired, the hash generated from the content management database 191 and the hash (main) can be verified thereafter. If the content management database 191 is illegally rewritten and does not match the hash (main), even if the hash (sub) is copied to the hash (main), the hash generated from the content management database 191 and the hash (Main) does not match, and the rewritten content management database 191 is not used.

  If the control unit 14 determines that the collation cannot be performed in s38, the control unit 14 performs error processing (s39). For example, an error message such as “Content cannot be reproduced” is displayed using UI processing.

  In the example shown in the figure, the content management function is executed at the time of content reproduction and the hash is compared with the content management database. However, other timings (for example, power-on timing, move-in timing, or move-in timing) are shown. The content management function may be executed at the timing of out) to perform hash (main) restoration and error processing.

  As described above, by duplicating the content management database, even if the built-in HDD 19 fails and the content management database 191 cannot be read, the copied content management database 121 is referred to. Each content can be reproduced. In particular, since the content management database 121 is stored in the flash memory 12 different from the built-in HDD 19, the possibility of disappearing to the content management database 121 is extremely low. The flash memory has a relatively smaller capacity than the HDD, but the content management database is similar to text data and is much smaller than the data amount of the content itself. Therefore, even if the amount of content increases, the amount of data in the content management database does not increase so much, so that the capacity of the flash memory is not reduced, and wear leveling (processing in which rewriting is distributed to the elements in the flash memory) ) Is low, and the possibility that the copied content management database 121 will be lost is extremely low. In the present embodiment, an example in which the content management database 191 is stored in the built-in HDD 19 is shown, but of course, it may be stored in another storage medium (for example, a flash memory prepared separately from the flash memory 12). However, even for flash memories such as NAND, the number of rewrites is limited or errors may occur, and it cannot be said that the failure rate is lower than that of HDDs. Even if it is left, the disadvantages are not increased. In particular, as long as the content is stored in the built-in HDD 19, it is not necessary to prepare another storage medium in order to duplicate the content management database.

  In addition, since the hash of the content management database is stored in the secure memory and checked as necessary, it is extremely difficult to illegally rewrite the content management database. For example, even if the count value of a certain content in the content management database is altered to 1, it does not match the hash stored in the secure memory 15, and the altered content management database is not used.

  Furthermore, since the copied content management database 121 is also stored as a separate hash (sub), if an error occurs when writing the hash (main) and the hash is not appropriate, In addition, the hash generated from the content management database 121 can be collated with the stored hash (sub), and the fault tolerance is further improved.

  Next, content backup will be described. FIG. 7A is a flowchart showing the operation of the NAS 1 during backup, and FIG. 7B is a conceptual diagram showing the content management state after backup.

  First, the control unit 14 receives content to be backed up by UI processing from the user (s51). In the UI processing, as described above, a list of contents stored in the NAS 1 (internal HDD 19 and cartridge HDD 20) is displayed on the screen of a device that reproduces content, and a screen for user operation is displayed for backup. This is a process of accepting content specification. When the user designates each content displayed on the screen and issues a backup instruction, the content backup is accepted.

  When receiving the backup, the control unit 14 copies the designated content (s52). In the backup, there are a case where the content stored in the internal HDD 19 is designated and copying is performed to the cartridge HDD 20, and a case where the content stored in the cartridge HDD 20 is designated and copying is performed to the internal HDD 19. Since this copy is a process of simply copying the encrypted content without performing decryption or re-encryption processing, it can be performed at high speed.

  Here, as shown in FIG. 7B, the content management database 191 and the content management database 121 are not updated and remain as they are. That is, even if there are a plurality of contents stored in the own apparatus, it is assumed that the contents are only one in terms of management. Even when the content is erased by the user's instruction, the content management database 191 and the content management database 121 are not updated.

  However, the content data is stored in both the built-in HDD 19 and the cartridge HDD 20, and may be displayed as another content stored in another folder on the UI screen, or only one content may be displayed. You may make it display. When only one content is displayed, the display is continued until all data of the corresponding content in the NAS 1 are deleted.

  For this reason, even if one content of the built-in HDD 19 or the cartridge HDD 20 is accidentally erased, it can be reproduced using the other content, and the other content can be copied and backed up again. Is possible. Even if the internal HDD 19 or the cartridge HDD 20 breaks down and the content cannot be read out, it can be played back using the backed up content, and can be copied and backed up again after repair. Is also possible.

  It is also possible to prepare a plurality of cartridge HDDs 20 and back up a large number of contents.

  Here, the cartridge HDD 20 is a storage medium that can be easily carried, but the content copied even when connected to other devices is encrypted using a local encryption key in the same way as the content of the copy source. Therefore, it cannot be played back on other devices.

  Therefore, no matter how many times the content is copied, it cannot be played back by another device, so that the copyright protection requirement can be satisfied.

  Next, the operation at the time of move-out will be described. FIG. 8 is a flowchart showing an operation at the time of move-out, and is a conceptual diagram showing a content management state after moving out content D in FIG.

  First, the control unit 14 receives content to be moved out by UI processing from the user (s71). Similarly to the above, the UI process displays a list of contents stored in the NAS 1 on the screen of a device that reproduces content (in this case, a device to be moved in) and displays a screen for user operation. This is a process of accepting designation of content to be out. In addition, a mode is also possible in which a list of contents is displayed on another device (a device other than the device to be moved in) having a WEB browser such as a personal computer, and designation of the content to be moved out is accepted. When the user designates each content displayed on the screen and gives a move-out instruction, the content move-out instruction is accepted.

  The control unit 14 decrypts the designated content using the local encryption key stored in the secure memory 15 (s72). Then, re-encryption is performed by DTCP-IP encryption / decryption processing using the DTLA device key stored in the secure memory 15 (s73). These decryption processing and re-encryption processing are also actually performed as hardware processing in the encryption processing section 16. Then, the control unit 14 outputs the encrypted content (s74). These decryption, re-encryption, and output processes are repeated until all data of the designated content is output (s75).

  After outputting all the data, the control unit 14 changes the count value of the moved-out content in the content management database 191 to 0 (s76). In other words, in the content management database, information indicating the content that has been moved out is written instead of erasing the information on the content that has been moved out.

  Then, the control unit 14 generates a hash (main) from the updated content management database 191 using the one-way function process, and stores it in the secure memory 15 (s77). Further, the control unit 14 copies the content management database 191 and stores it in the flash memory 12 as the content management database 121 (s78). Further, the control unit 14 generates a hash (sub) from the content management database 121 by using the one-way function process, and stores it in the secure memory (s79).

  Finally, the control unit 14 erases the moved-out content (s80). At this time, of the contents stored in the built-in HDD 19 and the cartridge HDD 20, all the moved-out contents are deleted. Even if a plurality of the same contents exist after backup, all the copied contents are deleted. For example, as shown in FIG. 9, when the content D of the internal HDD 19 is moved out, the content D of the internal HDD 19 and the content D of the backed up cartridge HDD 20 are also deleted.

  Further, as shown in FIG. 10, the control unit 14 of the NAS 1 executes a content management function at an arbitrary timing (for example, timing when the cartridge HDD 20 is connected), and content with a count value of 0 is stored in its own device (in particular, the cartridge). It is determined whether or not the data is still stored in the HDD 20) (s91). That is, it detects the content that is left unconnected when the cartridge HDD 20 is moved out. If there is content that remains, the content is deleted (s92).

  As described above, when the content is moved out, the information of the corresponding content is not deleted from the content management database, but the information (count value 0) indicating that the content has been moved out is stored. In addition, it is possible to determine whether or not the backed-up content is still stored, and by deleting the content, it is possible to prevent the content copied to the cartridge HDD 20 from being left unnecessarily. It is also useful from the viewpoint of copyright protection without leaving data. In particular, even when the backup is performed on a plurality of cartridge HDDs 20, since it will always be automatically deleted when connected, a lot of useless data is left without any special operation by the user. It can be prevented from remaining.

  As described above, the NAS 1 according to the present embodiment can easily back up content that is difficult to back up, such as copy-once, and satisfy the requirements for the copyright protection function. it can. In particular, after the move-out, all the backed-up content is automatically deleted, so that appropriate content management can be performed without requiring the user to perform a special operation.

  Even when the content management information cannot be read due to a failure (or error, etc.) of the HDD or flash memory, the NAS 1 of this embodiment reproduces the content because the content management database is duplicated. The risk of becoming impossible is very low.

1 ... NAS
2 ... HDD recorder 3 ... network 11 ... bus 12 ... flash memory 13 ... RAM
DESCRIPTION OF SYMBOLS 14 ... Control part 15 ... Secure memory 16 ... Encryption processing part 17 ... Network interface 18 ... HDD interface 19 ... Built-in HDD
20 ... cartridge HDD
121 ... Content management database (sub)
191 ... Content management database (main)

Claims (7)

First storage means and second storage means for storing encrypted content;
Content copy means for copying content stored in the first storage means to the second storage means;
Content management means for managing content based on content management information for managing the content;
Content management information copying means for copying the content management information;
A content storage device comprising:
The content storage device, wherein the content management means manages content using content management information copied by the content management information copying means when the content management information cannot be used. An erasure processing means for outputting and erasing the content;
The content management means, after outputting and erasing the content, records information indicating output in the content management information,
The erasure processing unit erases the stored content when information indicating output is recorded in the content management information and content corresponding to the information indicating output is stored in the own device. The content storage device according to claim 1, wherein: The content management information is stored in the first storage means,
A third storage means for storing the content management information as a hash;
The content management means determines whether or not the content management information is usable by collating a hash generated from the content management information with a hash stored in the third storage means. The content storage device according to claim 1, wherein: The third storage means further stores the copied content management information as a second hash,
The content management means collates a hash generated from the copied content management information with the second hash stored in the third storage means when the content management information cannot be used. 4. The content storage device according to claim 3, wherein it is determined whether or not the copied content management information is usable.   The content storage device according to claim 3, wherein the third storage unit is readable and writable only by an authenticated device.   6. The content storage device according to claim 1, wherein the content management information copied by the content management information copy unit is stored in a fourth storage unit. A program that is executed by a content storage device that includes first storage means and second storage means for storing content,
A content copy process for copying the content stored in the first storage means to the second storage means;
Content management processing for managing content based on content management information for managing the content;
A content management information copy process for copying the content management information,
The content management processing manages content using content management information copied in the content management information copy processing when the content management information cannot be used.

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