WO2011102080A1 - Content processing device, content sharing system, and content processing method - Google Patents

Abstract

Disclosed is a content processing device provided with: a storage unit (138) for storing a licence encryption key; a licence decryption unit (137) for acquiring a content key by decrypting an encrypted content key included in licence information acquired from an external storage medium (300), said decryption being performed using the licence encryption key stored in the storage unit (138); a licence encryption unit (136) for encrypting the content key decrypted by the licence decryption unit (137), said encryption being performed using a public key included in device public information selected from among a plurality of device public information items; and an export licence creation unit (134) for creating an export licence including the content key encrypted by the licence encryption unit (136) and a device identifier included in the device public information selected, and for storing the export licence in the external storage medium (300).

Description

Content processing apparatus, content sharing system, and content processing method

The present invention relates to a content processing device and a content sharing system for sharing content among a plurality of devices.

A conventional method for sharing contents among a plurality of mobile phones is disclosed in Patent Document 1. In the method disclosed in Patent Document 1, content downloaded from a communication network is encrypted with an encryption key generated from information unique to a SIM card and recorded on an external storage medium. If you want to view the content on another device, insert the SIM card with the external storage medium into the other device, generate the decryption key from the SIM card-specific information, and decrypt the content with the decryption key. It becomes.

JP 2006-013641 A

In the above method, an external storage medium storing the content and a SIM card must be attached to a device for viewing the content as a set, and the operation becomes complicated. In addition, this method cannot be applied to a device (such as a TV) that does not have a removable device identification device such as a SIM card.

Therefore, the present invention has been made in view of the above circumstances, and an object thereof is to provide a content processing apparatus and a content sharing system that can more easily share contents by a plurality of apparatuses.

The content processing apparatus according to an aspect of the present invention assigns a license for the content to another content processing apparatus in order to share the content stored in the external storage medium. Specifically, the external storage medium includes the content encrypted with a content key, license information including the content key encrypted with a license encryption key unique to the content processing apparatus, and the external storage The device public information of each of the plurality of content processing apparatuses permitted to access the medium is stored. The device public information includes a device identifier for identifying a content processing device and a public key corresponding to a secret key assigned to the content processing device identified by the device identifier. The content processing apparatus stores a storage unit that stores the license encryption key and the encrypted content key included in the license information acquired from the external storage medium in the storage unit. The device public information selected from among the plurality of device public information includes the decryption unit that obtains the content key by decrypting with the license encryption key and the content key decrypted by the decryption unit. Generating an export license including an encryption unit for encrypting with the public key, a content key encrypted by the encryption unit, and the device identifier included in the selected device public information; and An export license generation unit stored in the medium.

According to the above configuration, the license for the content can be transferred via the external storage medium in which the content is stored. As a result, it becomes possible to more easily share content among a plurality of content processing apparatuses. Note that “access to the external storage medium is permitted” means that the device public information is registered in the external storage medium.

The device public information may further include a public key certificate that proves the validity of the public key. The storage unit may further store a root certificate for proving the validity of the public key certificate included in each of the plurality of device public information. Then, when the validity of the public key certificate included in the selected device public information is proved by the root certificate, the encryption unit receives the content key decrypted by the decryption unit You may encrypt with a public key. This makes it possible to detect falsification of the device public information of the export destination device before assigning the license.

In addition, the export license generation unit may further include a hash value generated using the identifier and the content key included in the export license in the export license. As a result, it is possible to detect falsification of the export license by the content processing apparatus that acquires the export license.

Furthermore, the license information may include a copy control count indicating the number of times that the encrypted content key can be transferred. The export license generation unit may further include a predetermined value subtracted from the number of times of copy control included in the license information in the export license. Thereby, it is possible to prevent the license of the content from spreading without limitation.

Further, the storage unit may store export control information that holds the device identifier in association with an export counter that is an integrated value of the number of licenses assigned to the content processing apparatus identified by the device identifier. . The export license generation unit may add the predetermined value to the export counter associated with the device identifier included in the export license when the export license is generated. Thereby, it is possible to prevent an illegal license from being shared.

A content processing apparatus according to another aspect of the present invention acquires a license for the content from another content processing apparatus in order to share the content stored in the external storage medium. Specifically, the external storage medium is encrypted with the content encrypted with a content key, a device identifier for identifying the content processing device, and a public key corresponding to a secret key assigned to the content processing device. And an export license including the content key. The content processing apparatus includes: a storage unit that stores a license encryption key unique to the content processing apparatus; and the encryption included in the export license including the device identifier of the content processing apparatus acquired from the external storage medium The decrypted content key is decrypted with the secret key assigned to the content processing device to obtain the content key, and the content key decrypted by the decryption unit is stored in the storage unit. An encryption unit that encrypts with the license encryption key, and a license import processing unit that generates license information including the content key encrypted by the encryption unit and stores the license information in the external storage medium .

According to the above configuration, a license for the content can be acquired via the external storage medium in which the content is stored. As a result, it becomes possible to more easily share content among a plurality of content processing apparatuses.

The export license further includes an export counter that is an integrated value of the number of licenses assigned to the content processing device from the other content processing device. The storage unit further imports an apparatus identifier that identifies the other content processing apparatus and an import counter that is an integrated value of the number of licenses received from the content processing apparatus identified by the apparatus identifier in association with each other. Store control information. The license import processing unit is encrypted by the encryption unit only when the export counter included in the export license is larger than the import counter associated with the device identifier of the other content processing apparatus. License information including a content key may be generated and stored in the external storage medium. This can prevent unauthorized license exchange.

In addition, when the plurality of export licenses generated by the same content processing device are stored in the external storage medium, the content processing device acquires the export licenses in order from the smallest export counter value. The license information may be generated. Thereby, the export licenses can be read and processed in an appropriate order (generation order).

Further, the content processing apparatus may include an interface that can connect the external storage medium. Then, the export license input / output may be executed while the external storage medium is connected to the interface. The above external storage medium is premised on performing processing by directly connecting a highly portable storage medium such as a USB memory to a content processing apparatus. However, in the present invention, the content processing apparatus and the external storage medium may be connected via a communication network.

The content sharing system according to an aspect of the present invention shares content stored in an external storage medium between the first and second content processing apparatuses. Specifically, in the external storage medium, the content encrypted with a content key, and license information including the content key encrypted with a license encryption key unique to the first content processing device, Device public information of each of the first and second content processing apparatuses is stored. The device public information includes a device identifier for identifying a content processing device and a public key corresponding to a secret key assigned to the content processing device identified by the device identifier. Then, the first content processing device uses the first storage unit that stores the license encryption key and the encrypted content key included in the license information acquired from the external storage medium, as the first content processing device. A first decryption unit that obtains the content key by decrypting with the license encryption key stored in the storage unit; and the second content processing device that decrypts the content key decrypted by the first decryption unit. A first encryption unit that encrypts with the public key included in the device public information, a content key encrypted by the first encryption unit, and the device identifier of the second content processing device. An export license generation unit that generates an export license including the export license and stores the generated export license in the external storage medium. The second content processing device includes a second storage unit that stores a license encryption key unique to the second content processing device, and the device identifier of the second content processing device acquired from the external storage medium. The encrypted content key included in the included export license is decrypted with the secret key assigned to the content processing apparatus, and the second decryption unit that obtains the content key is decrypted with the second decryption unit A second encryption unit that encrypts the content key that has been encrypted with the license encryption key stored in the second storage unit, and a license that includes the content key encrypted by the second encryption unit A license import processing unit that generates information and stores the information in the external storage medium.

According to the above configuration, the license for the content can be exchanged via the external storage medium in which the content is stored. As a result, it becomes possible to more easily share content among a plurality of content processing apparatuses.

In the content processing method according to an aspect of the present invention, in order to share content stored in an external storage medium, the content license is transferred to another content processing apparatus. Specifically, the external storage medium is permitted to access the content encrypted with a content key, license information including the content key encrypted with a license encryption key, and the external storage medium. The device public information of each of the plurality of content processing apparatuses is stored. The device public information includes a device identifier for identifying a content processing device and a public key corresponding to a secret key assigned to the content processing device identified by the device identifier. The content processing method includes a decryption step of decrypting the encrypted content key included in the license information acquired from the external storage medium with the license encryption key, and acquiring the content key; The content key decrypted in the decryption step is encrypted with the public key included in the device public information selected from the plurality of device public information, and encrypted in the encryption step. Generating an export license including the content key and the device identifier included in the selected device public information, and storing the export license in the external storage medium.

The content processing method according to another aspect of the present invention acquires a license for the content from another content processing device in order to share the content stored in the external storage medium. Specifically, in the external storage medium, the content key encrypted with a content key and the content key encrypted with a public key corresponding to a device identifier for identifying itself and a secret key assigned to the content key. And an export license including Then, the content processing method decrypts the encrypted content key included in the export license including the device identifier obtained from the external storage medium with the assigned secret key, and determines the content key. A decryption step to obtain, an encryption step for encrypting the content key decrypted in the decryption step with a unique license encryption key, and license information including the content key encrypted in the encryption step And a license import processing step of generating and storing the license in the external storage medium.

According to the above configuration, a license for the content can be exchanged via the external storage medium in which the content is stored. As a result, it becomes possible to more easily share content among a plurality of content processing apparatuses.

FIG. 1 is a schematic diagram of a content sharing system according to the first embodiment. FIG. 2 is a functional block diagram of the content processing apparatus. FIG. 3 is a functional block diagram of the content protection processing unit. FIG. 4 is a diagram showing a data structure of import control information according to the first embodiment. FIG. 5 is a diagram showing a data structure of export control information according to the first embodiment. FIG. 6 is a diagram illustrating a data structure of the device specific information. FIG. 7 shows the data structure of the data recording unit. FIG. 8 is a diagram illustrating a data structure of the device public information. FIG. 9 shows the data structure of the license. FIG. 10 shows the data structure of the export license. FIG. 11 is a diagram illustrating a data structure of the recorded content management information. FIG. 12 is a flowchart showing processing when an external storage medium is connected. FIG. 13 is a screen display example for performing content use settings in an external storage medium. FIG. 14 is a flowchart showing the sharing initialization process. FIG. 15 is an example of a content viewing setting screen on another device. FIG. 16 is another example of a content viewing setting screen on another device. FIG. 17 is a flowchart showing content sharing processing. FIG. 18 is a flowchart showing the viewing availability status display process. FIG. 19 is a flowchart showing the export destination selection process. FIG. 20 is a flowchart showing the export process. FIG. 21 is a flowchart showing the export license generation process. FIG. 22 is a flowchart showing the import process. FIG. 23 is a flowchart showing license information generation processing. FIG. 24 is a flowchart showing the recording process. FIG. 25 is a schematic diagram of a content sharing system according to the second embodiment. FIG. 26 is a diagram showing a data structure of import control information according to the second embodiment. FIG. 27 is a diagram showing a data structure of export control information according to the second embodiment. FIG. 28 is a diagram showing a data structure of license falsification detection information according to the second embodiment.

(Embodiment 1)
A content sharing system 10 and a DTV (Digital TeleVision) 100, which is an example of a content processing apparatus, according to Embodiment 1 of the present invention will be described with reference to FIGS. FIG. 1 is a schematic diagram of a content sharing system 10. FIG. 2 is a functional block diagram of the DTV 100. FIG. 3 is a functional block diagram of the content protection processing unit 130 that is a component of the DTV 100. 4 to 6 are diagrams illustrating examples of data structures of various types of information stored in the storage unit 138 that is a component of the content protection processing unit 130. FIG. 7 to 11 are diagrams showing examples of data structures of various information stored in the external storage medium 300. FIG.

As shown in FIG. 1, the content sharing system 10 includes a plurality of DTVs 100 and 200 as content processing apparatuses, and an external storage medium 300. In this example, an external storage medium 300 is directly connected to the DTV 100. Furthermore, the DTV 100 is in a state where it can receive broadcast waves output from the broadcast station 1 via the broadcast network.

In the content sharing system 10 configured as described above, for example, the DTV 100 receives content from the broadcasting station 1, encrypts it, and stores it in the external storage medium 300. Further, the DTV 100 hands over the license of the content to the DTV 200. Thus, when the external storage medium 300 is connected to the DTV 200, the content can be viewed and the like on the DTV 200 as well.

However, the means for the DTV 100 to receive the content is not limited to the broadcast wave. For example, the content may be acquired via the Internet or may be acquired from another storage medium. Specific examples of the content processing apparatus are not limited to the DTVs 100 and 200. For example, a BD (Blu-ray Disc) player, a BD recorder, a DVD (Digital Versatile Disc) player, a DVD recorder, a video camera including an imaging unit, and the like. Needless to say, it may be. Further, the specific example of the external storage medium 300 is not particularly limited. For example, an external HDD (Hard Disc Drive), a USB (Universal Serial Bus) memory, an SD (Secure Digital) card, or an SD (Secure Digital) card is directly connected to the content processing apparatus. Any possible non-volatile storage medium can be employed.

As shown in FIG. 2, the DTV 100 includes a broadcast receiving unit 110, a content recording unit 120, a content protection processing unit 130, an external storage medium interface (I / F) 140, a screen display unit 150, and content playback. Unit 160 and user request receiving unit 170.

The broadcast receiving unit 110 receives content from a broadcasting station and outputs the content to one or both of the content recording unit 120 and the screen display unit 150. The content recording unit 120 temporarily records (records) the content received by the broadcast receiving unit 110 and outputs the content to the content protection processing unit 130. The screen display unit 150 displays the content acquired from the broadcast receiving unit 110 or the content reproduction unit 160. The content reproduction unit 160 reproduces the content stored in the external storage medium 300 (displays it on the screen display unit 150). The user request receiving unit 170 receives an instruction from the user and outputs it to the content protection processing unit 130.

The content protection processing unit 130 acquires content from the content recording unit 120, encrypts it, and stores it in the external storage medium 300. In addition, the content can be viewed by other content processing devices such as the DTV 200. Furthermore, the content stored in the external storage medium 300 is acquired, and the content is displayed on the screen display unit 150 via the content reproduction unit 160. Details of the content protection processing unit 130 will be described later with reference to FIG.

The external storage medium I / F 140 is an interface for connecting the external storage medium 300. Specific examples of the interface are not particularly limited. For example, any interface that can be directly connected to the external storage medium 300 such as a USB, a PCI (Peripheral Component Interconnect) bus, and an SD card slot can be employed.

The external storage medium 300 includes an external storage medium I / F 310 and a data recording unit 320. The external storage medium I / F 310 is an interface corresponding to the external storage medium I / F 140 of the DTV 100. The data recording unit 320 records content, license information of the content, and the like. Details of the information recorded in the data recording unit 320 will be described later.

As shown in FIG. 3, the content protection processing unit 130 includes a content encryption / decryption processing unit 131, a license management unit 132, a license import processing unit 133, an export license generation unit 134, a certificate verification unit 135, A license encryption unit 136, a license decryption unit 137, and a storage unit 138 are provided.

The content encryption / decryption processing unit 131 encrypts the content acquired from the content recording unit 120 with the content key and stores it in the external storage medium 300. Also, the encrypted content acquired from the external storage medium 300 is decrypted with the content key and output to the content reproduction unit 160. The content key is acquired from the license management unit 132.

The license management unit 132 controls other functional blocks of the content protection processing unit 130 and manages licenses necessary for using the content stored in the external storage medium 300. The license import processing unit 133 executes a process of acquiring (importing) a license assigned from another content processing apparatus (for example, the DTV 200). The export license generation unit 134 executes processing for assigning a license to another content processing apparatus (for example, the DTV 200). The certificate verification unit 135 verifies the validity of a public key certificate (described later) stored in the external storage medium 300. The license encryption unit 136 encrypts information related to the license. The license decryption unit 137 decrypts information related to the license. The storage unit 138 stores various information necessary for license exchange and the like. The specific processing content of each component described above will be described later with reference to a flowchart.

The storage unit 138 stores import control information 138a, export control information 138b, root CA certificate 138c, license falsification detection information 138d, and device specific information 138e. The storage unit 138 may employ any nonvolatile memory such as an HDD, an EEPROM (Electrically Erasable Programmable Read Only Memory), or a flash memory.

As shown in FIG. 4, the import control information 138a holds a device identifier and an import counter in association with each other. The device identifier is used to identify the content processing apparatus. For example, “DTV-ID-1” is assigned to the DTV 100, and “DTV-ID-2” is assigned to the DTV 200, for example. The import counter is an integrated value of the number of licenses received from the content processing apparatus identified by the corresponding device identifier. That is, the import control information 138a holds the number of licenses received by the DTV 100 so far for each content processing apparatus.

As shown in FIG. 5, the export control information 138b holds a device identifier and an export counter in association with each other. The export counter is an integrated value of the number of licenses assigned to the content processing apparatus identified by the corresponding device identifier. That is, the export control information 138b holds the number of licenses that the DTV 100 has transferred so far, integrated for each content processing apparatus.

The root CA certificate 138c is a root certificate of a public key certificate that each content processing apparatus has. The public key certificate of each content processing apparatus is stored in the external storage medium 300. Then, the certificate verification unit 135 verifies the validity of the public key certificate acquired from the external storage medium 300 using the root CA certificate.

In the following description, an example in which the public key certificate of each content processing apparatus is stored in advance in the external storage medium 300 and shared is shown, but the public key certificate sharing method is not limited to this. For example, the content processing devices may exchange public key certificates in advance, and each content processing device may store the public key certificates of other content processing devices in the storage unit 138 of its own device. Alternatively, in a situation where each content processing apparatus is connected via a network, it may be acquired through the network when necessary.

The license falsification detection information 138d is information for detecting whether or not the license management information (described later) of the DTV 100 stored in the external storage medium 300 has been falsified. Although a specific example is not specifically limited, For example, the hash value obtained by inputting all the items of license management information into the predetermined 1st hash function may be sufficient.

The device unique information 138e is information unique to the DTV 100. As shown in FIG. 6, the device identifier “DTV-ID-1”, the device name “TV1”, the public key certificate “device-cert-1”, A secret key “seckey-1” and a license encryption key “licensekey-1” are included. The public key certificate “device-cert-1” is for certifying the validity of the public key held by the DTV 100. Note that the public key held by the DTV 100 is embedded in the public key certificate. The secret key “seckey-1” corresponds to the public key held by the DTV 100. That is, the secret key “seckey-1” can decrypt the data encrypted with the public key embedded in the public key certificate “device-cert-1”. The license encryption key “licensekey-1” is a unique key (not overlapping) of the DTV 100, and is used for encryption and decryption of the content key included in the license.

As shown in FIG. 7, the data recording unit 320 of the external storage medium 300 stores license management information 321, export license 322, recorded content management information 323, and recorded content 324.

The license management information 321 includes license management information 321a including device disclosure information and licenses # 1, # 2,..., #N corresponding to viewable contents # 1, # 2,. , 321b are held for each content processing apparatus. For example, as shown in FIG. 8, the device public information of the DTV 100 includes a device identifier “DTV-ID-1”, a device name “TV1”, and a public key certificate “device-cert-1”. This device public information is written by the license management unit 132 when the external storage medium 300 is first connected to the DTV 100. Licenses # 1, # 2,..., #N are licenses corresponding to the contents # 1, # 2,.

For example, as shown in FIG. 9, the license # 1 includes a content identifier “CID-1”, a copy control count “10”, and a content key “ckey-1”. The content key is encrypted with the license encryption key of the DTV 100. Note that the number of times of copy control indicates the number of times that the license can be assigned. That is, the DTV 100 can assign the license # 1 to another content processing apparatus up to 10 times. The number of times of copy control is also the maximum number of content # 1 that can be dubbed to other media. This copy control count is decremented by 1 each time license # 1 is assigned to another content processing apparatus or content # 1 is dubbed to another medium. When the copy control count becomes 0, the license # 1 of the DTV 100 is deleted from the external storage medium 300.

In the export license 322, a license assigned from one content processing apparatus to another content processing apparatus is temporarily stored. For example, the export license 322 assigned from the DTV 100 to the DTV 200 includes an export side device identifier “DTV-ID-1”, an import side device identifier “DTV-ID-2”, and a content identifier, as shown in FIG. It includes “CID-1”, copy control count “1”, export counter “100”, content key “ckey-1”, and falsification detection information (hash value). The content key “ckey-1” is encrypted with the public key of the DTV 200. Further, the falsification detection information includes a second hash function in which an export side device identifier, an import side device identifier, a content identifier, a copy control count, an export counter before encryption and a content key are determined in advance. This is the hash value obtained by inputting to. Note that the second hash function may be the same as or different from the first hash function described above.

In the recorded content management information 323, information of contents # 1, # 2,..., #N included in the recorded content 324 is held. Specifically, as shown in FIG. 11, for each content # 1, # 2,..., #N, a file name including a content entity, a content identifier, and a content name are associated and stored. Has been.

The recorded content 324 holds entity files of content # 1, # 2,. Each content # 1, # 2,..., #N is encrypted with content keys # 1, # 2,. In addition, the content keys # 1, # 2,..., #N are unique (non-overlapping) keys to the contents # 1, # 2,.

Next, the operation of the DTV 100 as the content processing apparatus will be described with reference to FIGS. 12, 14, and 17 to 24 are flowcharts showing the operation of the DTV 100. 13, 15, and 16 are display examples displayed on the screen display unit 150 of the DTV 100.

First, the processing when the external storage medium 300 is connected to the DTV 100 will be described with reference to FIG. First, the license management unit 132 repeatedly reads the license management information 321 (S101) until all the license management information 321 stored in the data recording unit 320 is read (S102). Next, the license management unit 132 determines whether or not the license management information 321a having the device identifier of the own device (DTV 100) exists in the read license management information 321 (S103).

When the license management information 321a of the own device does not exist (No in S103), the license management unit 132 executes a sharing initialization process (S104). On the other hand, when the license management information 321a of the own device exists (Yes in S103), the license management unit 132 inputs all items of the license management information 321a to the first hash function and calculates a hash value ( S105). Then, the license management unit 132 compares the calculated hash value with the license falsification detection information 138d stored in the storage unit 138 (S106).

When the calculated hash value and the license falsification detection information 138d do not match (No in S106), the license management unit 132 executes error processing assuming that the license management information 321a has been falsified (S107). The content of the error processing is not particularly limited. For example, a screen may be displayed on the screen display unit 150 that warns the possibility of falsification and allows the user to select whether to execute the shared initialization processing S104 again. Good.

On the other hand, if the two match (Yes in S106), the license management unit 132 monitors the input of a request from the user to the user request receiving unit 170 (S108). For example, options such as “content sharing process”, “import process”, and “recording process” may be displayed on the screen display unit 150 and the user may select any of these options. Then, the license management unit 132 executes any of content sharing processing (S109), import processing (S110), and recording processing (S111) in response to a request from the user.

Next, the shared initialization process will be described with reference to FIGS. First, the license management unit 132 causes the screen display unit 150 to display an “external storage medium initialization screen” as shown in FIG. 13 (S201). Next, the license management unit 132 monitors a user request input to the user request receiving unit 170 (S202). When the user request reception unit 170 detects that the “cancel” button shown in FIG. 13 is pressed (No in S202), the license management unit 132 ends the sharing initialization process.

On the other hand, when the user request receiving unit 170 detects that the “initialization” button shown in FIG. 13 has been pressed (Yes in S202), the license management unit 132 obtains the device identifier, the device from the device specific information 138e. The name and public key certificate are acquired, and license management information (more specifically, device public information) 321a is generated (S203).

Next, the license management unit 132 inputs hash values obtained by inputting all items (that is, device identifier, device name, and public key certificate) of the generated license management information 321a into the first hash function. The license alteration detection information 138d is stored in the storage unit 138 (S204). Then, the license management unit 132 stores the generated license management information 321a in the data recording unit 320 of the external storage medium 300 (S205).

The above-described sharing initialization process enables the content processing apparatus to acquire a license from another content processing apparatus (that is, access to the external storage medium is permitted). This sharing initialization process is typically executed only when the external storage medium 300 is first connected to the content processing apparatus.

Next, content sharing processing will be described with reference to FIGS. First, the license management unit 132 reads the recorded content management information 323 from the external storage medium 300 and displays a content list (upper right in FIG. 15) on the screen display unit 150 (S301). Further, the license management unit 132 acquires the content identifier of the content selected from the content list from the recorded content management information 323 (S302).

Further, the license management unit 132 displays the details of the content identified by the acquired content identifier on the screen display unit 150 (S303, S304). The license management unit 132 performs the above process (No in S302 to S304 and S305) each time another content is selected until the user presses either the “OK” button or the “Cancel” button. ).

For example, as shown in FIG. 15, when “program name BBB” corresponding to the content # 2 is selected, the license management unit 132 displays a preview of the content (upper left in FIG. 15), the number of times that can be copied, and other devices. The display / non-viewability status (lower left in FIG. 15) and the like are displayed on the screen display unit 150. Note that the value of the number of times of copy control of license # 2 included in the license management information 321 of the content processing apparatus (DTV 100 in the example of FIG. 15) to which the external storage medium 300 is connected is displayed as the number of possible copies. . In addition, in the viewability status of other devices, whether or not the license # 2 is included in the license management information 321 of each device is displayed. Details will be described later.

Next, when the user request reception unit 170 detects that the “decision” button shown in FIG. 15 is pressed (Yes in S306), the license management unit 132 performs the export destination selection process (S307) and export. The process (S308) is executed. On the other hand, when the user request reception unit 170 detects that the “cancel” button shown in FIG. 15 has been pressed (No in S306 and Yes in S307), the license management unit 132 ends the content sharing process. To do.

Next, with reference to FIG. 18, display processing for viewing availability is described. First, the license management unit 132 reads unread license management information 321 from the external storage medium 300 (S401). Since all the license management information 321 has already been read when the external storage medium 300 is connected, the following processing may be executed using this, or may be read again in the viewing availability display processing. Also good.

Next, the license management unit 132 adds the license (that is, license # 2) corresponding to the content identifier of the content (content # 2 in the example of FIG. 15) selected in the content sharing process to the read license management information 321. Is included (S402).

If the license corresponding to the selected content is included (Yes in S402), the license management unit 132 displays the device name corresponding to the license management information 321 and the characters “OK” on the screen display unit 150. Let On the other hand, if the corresponding license is not included (No in S402), the license management unit 132 causes the screen display unit 150 to display the device name corresponding to the license management information 321 and the characters “impossible”. Then, the license management unit 132 executes the above processing (S401 to S404) for all license management information (S405). When the above processing is completed, the presence / absence of a license for the selected content (content # 2 in the example of FIG. 15) is displayed for each content processing device, as shown in “Status of viewing on other devices” in FIG. The

Next, the export destination selection process will be described with reference to FIG. First, as shown in FIG. 16, the license management unit 132 selects an export destination of a license for viewing the content selected in the content sharing process (FIG. 17) (content # 2 in the example of FIG. 15). A check box for this is displayed on the screen display unit 150 (S501).

In the example of FIG. 16, since the TV 2 already holds the license for the content # 2, “Done” is displayed. On the other hand, a check box for inquiring the user whether or not to execute the export process is displayed on the TV 3 and the DVR 1 that do not yet hold the license for the content # 2. In addition, the license management unit 132 displays the number of times the selected content # 2 can be copied on the screen display unit 150 (S502). This number of possible copies corresponds to the value of “copy control count” of license # 2 included in the license management information 321 of the content processing apparatus (DTV 100 in the example of FIG. 16) to which the external storage medium 300 is connected.

Next, the license management unit 132 monitors the input of a request from the user to the user request receiving unit 170 (S503). When the user request receiving unit 170 detects a user input operation (Yes in S503), the license management unit 132 adds the check (S504), deletes the check (S505), presses the enter button (S506), and cancels the input operation. It is determined whether the button is pressed (S507).

In the case of “check addition”, that is, when the user performs an operation of adding a check to any of the displayed check boxes (Yes in S504), the license management unit 132 subtracts 1 from the displayed number of possible copies. (S508). On the other hand, when “check deletion”, that is, when the user performs an operation of deleting a check from one of the displayed check boxes (Yes in S505), the license management unit 132 sets 1 to the number of permitted copies displayed. Are added (S509). In addition, the license management unit 132 causes the screen display unit 150 to change the display contents every time “check addition” and “check deletion” are performed.

Further, when the determination button is pressed (Yes in S506), the license management unit 132 acquires a list of device identifiers of the selected content processing apparatus (to which the check box is added) (referred to as “export destination device”). Then, the export destination selection process ends (S510). In the example of FIG. 16, the device identifier of the TV 3 is acquired. On the other hand, when the cancel button is pressed (Yes in S507), the license management unit 132 ends the export destination selection process without performing any special process.

Next, the export process will be described with reference to FIG. First, the license management unit 132 acquires a public key certificate from the license management information of the export destination device (TV3 in the example of FIG. 16) (S601). Next, the license management unit 132 causes the certificate verification unit 135 to verify the validity of the acquired public key certificate using the root CA certificate 138c stored in the storage unit 138 (S602).

If it is determined that the acquired public key certificate is authentic (Yes in S603), the license management unit 132 uses the content key encrypted from the license # 2 included in the license management information 321a of the own device. The license encryption key is acquired from the device specific information 138e stored in the storage unit 138. Then, the license management unit 132 causes the license decryption unit 137 to decrypt the encrypted content key using the license encryption key (S604).

Next, the license management unit 132 subtracts 1 from the copy control count included in the license management information 321a of the own device (S605). When the copy control count becomes 0, the license management unit 132 deletes the license from the license management information 321a of the own device.

Also, the license management unit 132 inputs all items of the updated license management information 321a (subtracts the number of times of copy control) to the first hash function to obtain a hash value, and stores it as license falsification detection information 138d It is stored in 138 (S606). Then, the license management unit 132 stores the updated license management information 321a in the data recording unit 320 of the external storage medium 300 (S607).

Next, the license management unit 132 causes the export license generation unit 134 to execute an export license generation process (S608), and stores the generated export license 322 in the data recording unit 320 of the external storage medium 300 (S609). The license management unit 132 executes the above process for all the export destination devices selected in the export destination selection process (S610).

Next, the export license generation process will be described with reference to FIG. First, the export license generation unit 134 stores the device identifier of its own device in the export license 322 as the export device identifier and the device identifier of the export destination device as the import device identifier (S701). Next, the export license generation unit 134 stores the content identifier to be exported and the copy control information (specifically, a predetermined value subtracted from the number of copy controls in the export process) in the export license 322 (S702). . Further, the export license generation unit 134 stores the content key decrypted in the export process in the export license 322 (S703).

Next, the export license generation unit 134 confirms whether or not an export counter associated with the device identifier of the export destination device exists in the export control information 138b (S704). When the export counter does not exist (No in S705), the export license generation unit 134 associates the device identifier of the export destination device with the export counter (0 is set as an initial value), and export control information 138b. Add to.

Next, the export license generation unit 134 adds 1 to the export counter associated with the device identifier of the export destination device (S706).

Next, the export license generation unit 134 inputs items from “export device identifier” to “content key” of the export license 322 to the second hash function, and uses the acquired hash value as the falsification detection information in the export license 322. Store (S707). Finally, the export license generation unit 134 acquires the public key from the public key certificate included in the license management information of the export destination device. Then, the license encryption unit 136 encrypts the export counter and content key of the export license 322 using the acquired public key (S708).

Through the above processing, the license of content # 2 held by the content processing device (DTV 100) can be transferred to another content processing device (TV 3). The assigned license is imported when the external storage medium 300 is connected to the other content processing apparatus.

Next, with reference to FIG. 22, an import process for importing the assigned license will be described. First, the license import processing unit 133 checks whether or not the export license 322 addressed to its own device exists in the data recording unit 320 of the external storage medium 300 (S801). If the export license 322 addressed to the own device exists (Yes in S801), the license import processing unit 133 reads the export license 322 from the data recording unit 320 (S802).

When a plurality of export licenses 322 generated by the same content processing device (that is, the same device identifier on the export side) are recorded in the data recording unit 320, the license import processing unit 133 The export counter values of the export licenses 322 are compared. Then, the export license 322 having the smallest export counter value is read in order.

Next, the license import processing unit 133 causes the license decryption unit 137 to decrypt the encrypted export counter and content key included in the acquired export license 322 using the private key held in the device specific information 138e. (S803). Further, the license import processing unit 133 inputs items from “export device identifier” to “content key” of the export license 322 to the second hash function, and calculates a hash value (S804).

Next, the license import processing unit 133 compares the calculated hash value with the falsification detection information stored in the export license 322 (S805). If the two do not match (No in S805), the license import processing unit 133 determines that the export license 322 is invalid (possibly altered), discards it, and executes processing to read the next export license 322 To do.

On the other hand, if the two match (Yes in S805), the license import processing unit 133 acquires the import counter corresponding to the export device identifier of the export license 322 from the import control information 138a (S806). Then, the license import processing unit 133 determines the size relationship between the export counter of the export license 322 and the import counter acquired from the import control information 138a (S807).

When the value of the export counter is equal to or less than the import counter (No in S807), the license import processing unit 133 determines that the export license 322 is invalid (possibly falsified) and discards the next export license 322. The process of reading out is executed. On the other hand, when the value of the export counter is larger than the import counter (Yes in S807), the license import processing unit 133 executes a license information generation process (S808). Then, the license import processing unit 133 executes the above processing on all the export licenses 322 addressed to the own device (S809).

Next, the license information generation process will be described with reference to FIG. First, the license import processing unit 133 acquires the license management information 321 of its own device from the data recording unit 320 of the external storage medium 300. Then, all items of the acquired license management information 321 are input to the first hash function, and a hash value is calculated (S901).

Next, the license import processing unit 133 compares the calculated hash value with the license falsification detection information 138d stored in the storage unit 138 (S902). If the two do not match (No in S902), the license import processing unit 133 determines that the license management information 321 is invalid (possibly altered), and ends the license information generation process.

On the other hand, if the two match (Yes in S902), the license import processing unit 133 uses the license key included in the device specific information 138e for the content key decrypted in the import processing to the license encryption unit 136. Is encrypted (S903). Then, the license import processing unit 133 generates a license with the content identifier and copy control count included in the export license 322, and the encrypted content key, and adds the license to the read license management information 321 (S904).

Next, the license import processing unit 133 inputs all items of the updated license management information 321 to the first hash function to calculate a hash value, and obtains the license falsification detection information 138d. The data is stored in the storage unit 138 (S905). Next, the license import processing unit 133 overwrites the import counter corresponding to the export side device identifier with the value of the export license included in the export license 322 (S906). Then, the license import processing unit 133 stores the updated license management information 321 in the data recording unit 320 of the external storage medium 300 (S907).

Through the above processing, licenses transferred from other content processing devices can be imported. The export license 322 is deleted from the external storage medium 300 after the import process is executed.

Next, the recording process will be described with reference to FIG. First, the license management unit 132 reads the recorded content management information 323 from the data recording unit 320 of the external storage medium 300, and generates a new content identifier that does not overlap with the existing content identifier (S1001). In addition, the license management unit 132 generates a new content key (not overlapping with other content keys). Then, the license management unit 132 causes the content encryption / decryption processing unit 131 to encrypt the content acquired from the content recording unit 120 using the newly generated content key (S1002). Further, the license management unit 132 determines the copy control count of the content based on the copyright information included in the broadcast wave (S1003).

Next, the license management unit 132 causes the license encryption unit 136 to encrypt the generated content key using the license encryption key included in the device specific information 138e. Then, the license management unit 132 generates a new license including the newly generated content identifier, the determined copy control count, and the encrypted content key (S1004).

Next, the license management unit 132 reads the license management information 321 of the own device from the data recording unit 320 of the external storage medium 300, inputs all items of the license management information 321 to the first hash function, and performs hashing. A value is calculated (S1005). Then, the license management unit 132 compares the calculated hash value with the license falsification detection information 138d stored in the storage unit 138 (S1006).

If the two do not match (No in S1006), the license management unit 132 ends the recording process, assuming that the license management information 321 is not valid (possibly altered). On the other hand, if the two match (Yes in S1006), the license management unit 132 adds the newly generated license to the license management information 321 of the own device, and the license management information 321 updated (license added). A hash value obtained by inputting all of the items into the first hash function is stored in the storage unit 138 as license falsification detection information 138d (S1007).

Next, the license management unit 132 stores the updated license management information 321 in the data recording unit 320 of the external storage medium 300 (S1008). In addition, the license management unit 132 adds the newly generated content identifier, the content name and the file name corresponding to the content identifier to the recorded content management information 323, and is updated (added new content information). The content management information 323 is stored in the data recording unit 320 of the external storage medium 300 (S1009). Furthermore, the license management unit 132 stores the content in the data recording unit 320 of the external storage medium 300 with the file name indicated in the recorded content management information 323 (registers it in the recorded content 324).

According to each of the above processes, the license can be shared among a plurality of content processing apparatuses by assigning the content key that is a license without duplicating the content itself. In addition, since the license for each content processing apparatus permitted to view the content is stored in the external storage medium 300 together with the content, sharing of the content by the plurality of content processing apparatuses becomes easier.

In the first embodiment, an example is shown in which processing is performed by directly connecting the external storage medium 300 to the external storage medium I / F 140 of the DTV 100. However, the present invention is not limited to this example. The medium 300 may be connected via a communication network. In this case, the external storage medium 300 can logically handle a plurality of storage media distributed on the network as one storage medium.

(Embodiment 2)
Next, the content sharing system 20 according to the second embodiment of the present invention will be described with reference to FIGS. FIG. 25 is a schematic diagram of the content sharing system 20. 26 to 28 are diagrams showing a data structure in the storage unit 138. FIG. In addition, description of a common point with Embodiment 1 is abbreviate | omitted, and it demonstrates centering around difference.

A plurality of external storage media 300, 400, 500 are detachable from the DTVs 100, 200 according to the second embodiment. Note that the data structure of the external storage media 400 and 500 is the same as that of the external storage medium 300 shown in FIGS. However, an external storage medium identifier is assigned to each of the external storage media 300, 400, and 500 according to the second embodiment. For example, the external storage medium identifier of the external storage medium 300 is “MEDIA-ID-1”, the external storage medium identifier of the external storage medium 400 is “MEDIA-ID-2”, and the external storage medium identifier of the external storage medium 500 is “MEDIA”. -ID-3 ”.

FIG. 26 is a diagram showing a data structure of the import control information 138a according to the second embodiment. The import control information 138a shown in FIG. 26 holds the data structure shown in FIG. 4 for each external storage medium identifier. FIG. 27 is a diagram showing a data structure of the export control information 138b according to the second embodiment. The export control information 138b shown in FIG. 27 holds the data structure shown in FIG. 5 for each external storage medium identifier. Furthermore, FIG. 28 is a diagram showing a data structure of the license falsification detection information 138d. The license falsification detection information 138d shown in FIG. 28 associates the hash value of the license management information 321 of the own device with the external storage medium identifiers of the external storage media 300, 400, 500 in which the license management information 321 is stored. Hold.

Next, differences from the first embodiment when the content processing apparatus according to the second embodiment performs each process shown in FIGS. 12 to 24 will be described.

First, in the processing at the time of connecting the external storage medium shown in FIG. 12, the content processing apparatus according to the second embodiment acquires the external storage medium identifier of the connected external storage medium. Further, the content processing apparatus compares the calculated hash value with the license falsification detection information 138d corresponding to the acquired external storage medium identifier (S106).

Next, in the sharing initialization process shown in FIG. 14, the content processing apparatus according to the second embodiment associates the calculated hash value with the external storage medium identifier of the connected external storage medium, and It stores in the storage unit 138 as falsification detection information 138d (S204).

Next, in the export process shown in FIG. 20, the content processing apparatus according to the second embodiment associates the calculated hash value with the external storage medium identifier of the external storage medium that is currently connected, and changes the license. The detection information 138d is stored in the storage unit 138 (S606).

Next, in the export license generation process shown in FIG. 21, the content processing apparatus according to the second embodiment is associated with the external storage medium identifier of the currently connected external storage medium and the export destination device identifier. The existence of the export counter is confirmed (S704). If the export counter does not exist (No in S704), the content processing apparatus creates export control information with the export counter set to 0 in association with the external storage medium identifier and the device identifier (S705). Further, the content processing apparatus increments the export counter (S706).

Next, in the import process shown in FIG. 22, the content processing apparatus according to the second embodiment uses the import counter associated with the external storage medium identifier of the currently connected external storage medium and the export side apparatus identifier. Is acquired (S806).

Next, in the license information generation process shown in FIG. 23, the content processing apparatus according to Embodiment 2 associates the calculated hash value with the external storage medium identifier of the currently connected external storage medium, The license alteration detection information 138d is stored in the storage unit 138 (S905). In addition, the content processing apparatus overwrites and saves the import counter associated with the external storage medium identifier of the currently connected external storage medium and the export side device identifier with the export counter of the export license 322 (S906).

Next, in the recording process shown in FIG. 24, the content processing apparatus according to the second embodiment compares the calculated hash value with the license falsification detection information 138d corresponding to the currently connected external storage medium identifier. (S1006). Further, the content processing apparatus associates the newly calculated hash value with the external storage medium identifier of the currently connected external storage medium, and saves it in the storage unit 138 as the license falsification detection information 138d (S1007).

According to each of the above processes, the contents stored in each of the plurality of external storage media 300, 400, 500 can be shared by the plurality of content processing apparatuses.

(Other embodiments)
Although the present invention has been described based on the above embodiment, it is needless to say that the present invention is not limited to the above embodiment. The following cases are also included in the present invention.

Each of the above devices is specifically a computer system including a microprocessor, ROM, RAM, a hard disk unit, a display unit, a keyboard, a mouse, and the like. A computer program is stored in the RAM or the hard disk unit. Each device achieves its functions by the microprocessor operating according to the computer program. Here, the computer program is configured by combining a plurality of instruction codes indicating instructions for the computer in order to achieve a predetermined function.

Some or all of the constituent elements constituting each of the above-described devices may be configured by a single system LSI (Large Scale Integration). The system LSI is an ultra-multifunctional LSI manufactured by integrating a plurality of component parts on one chip, and specifically, a computer system including a microprocessor, a ROM, a RAM, and the like. is there. A computer program is stored in the RAM. The system LSI achieves its functions by the microprocessor operating according to the computer program.

Some or all of the constituent elements constituting each of the above devices may be constituted by an IC card or a single module that can be attached to and detached from each device. The IC card or module is a computer system that includes a microprocessor, ROM, RAM, and the like. The IC card or the module may include the super multifunctional LSI described above. The IC card or the module achieves its functions by the microprocessor operating according to the computer program. This IC card or this module may have tamper resistance.

The present invention may be the method described above. Further, the present invention may be a computer program that realizes these methods by a computer, or may be a digital signal composed of a computer program.

The present invention also relates to a computer-readable recording medium capable of reading a computer program or a digital signal, such as a flexible disk, hard disk, CD-ROM, MO, DVD, DVD-ROM, DVD-RAM, BD (Blu-ray Disc), It may be recorded in a semiconductor memory or the like. Further, it may be a digital signal recorded on these recording media.

Further, the present invention may transmit a computer program or a digital signal via an electric communication line, a wireless or wired communication line, a network represented by the Internet, a data broadcast, or the like.

Further, the present invention may be a computer system including a microprocessor and a memory. The memory may store the computer program, and the microprocessor may operate according to the computer program.

Also, the program or digital signal may be recorded on a recording medium and transferred, or the program or digital signal may be transferred via a network or the like, and may be implemented by another independent computer system.

The above embodiment and the above modifications may be combined.

As mentioned above, although embodiment of this invention was described with reference to drawings, this invention is not limited to the thing of embodiment shown in figure. Various modifications and variations can be made to the illustrated embodiment within the same range or equivalent range as the present invention.

The present invention is advantageously used for a content processing apparatus and a content sharing system.

1 Broadcasting station 10,20 Content sharing system 100,200 DTV
110 broadcast receiving unit 120 content recording unit 130 content protection processing unit 131 content encryption / decryption processing unit 132 license management unit 133 license import processing unit 134 export license generation unit 135 certificate verification unit 136 license encryption unit 137 license decryption unit 138 storage unit 138a Import control information 138b Export control information 138c Root CA certificate 138d License falsification detection information 138e Device specific information 140, 310 External storage medium I / F
DESCRIPTION OF SYMBOLS 150 Screen display part 160 Content reproducing part 170 User request | requirement receiving part 300,400,500 External storage medium 320 Data recording part 321,321a, 321b License management information 322 Export license 323 Recording content management information 324 Recording content

Claims (12)

A content processing apparatus that assigns a license for the content to another content processing apparatus in order to share the content stored in the external storage medium,
The external storage medium includes the content encrypted with a content key, license information including the content key encrypted with a license encryption key unique to the content processing apparatus, and access to the external storage medium. The device public information of each of a plurality of permitted content processing devices is stored,
The device public information includes a device identifier for identifying a content processing device, and a public key corresponding to a secret key assigned to the content processing device identified by the device identifier,
The content processing apparatus
A storage unit for storing the license encryption key;
A decryption unit that decrypts the encrypted content key included in the license information acquired from the external storage medium with the license encryption key stored in the storage unit, and acquires the content key;
An encryption unit that encrypts the content key decrypted by the decryption unit with the public key included in the device public information selected from among the plurality of device public information;
An export license generating unit that generates an export license including the content key encrypted by the encryption unit and the device identifier included in the selected device public information, and stores the export license in the external storage medium. Processing equipment. The device public information further includes a public key certificate that proves the validity of the public key,
The storage unit further stores a root certificate for proving the validity of the public key certificate included in each of the plurality of device public information,
When the validity of the public key certificate included in the selected device public information is proved by the root certificate, the encryption unit uses the content key decrypted by the decryption unit as the public key. The content processing device according to claim 1, wherein the content processing device is encrypted with The content processing apparatus according to claim 1, wherein the export license generation unit further includes a hash value generated using the identifier and the content key included in the export license in the export license. The license information further includes a copy control count indicating the number of times that the encrypted content key can be transferred,
The content processing apparatus according to any one of claims 1 to 3, wherein the export license generation unit further includes a predetermined value subtracted from the copy control count included in the license information in the export license. The storage unit further stores export control information that holds the device identifier in association with an export counter that is an integrated value of the number of licenses assigned to the content processing device identified by the device identifier,
The content processing apparatus according to claim 4, wherein the export license generation unit adds the predetermined value to the export counter associated with the device identifier included in the export license when the export license is generated. A content processing apparatus for acquiring a license for the content from another content processing apparatus in order to share the content stored in the external storage medium,
In the external storage medium, the content encrypted with a content key, a device identifier for identifying the content processing device, and the content encrypted with a public key corresponding to a secret key assigned to the content processing device And the export license including the key
The content processing apparatus
A storage unit for storing a license encryption key unique to the content processing apparatus;
Decrypting the encrypted content key included in the export license including the device identifier of the content processing device acquired from the external storage medium with the secret key assigned to the content processing device, and the content key A decryption unit for obtaining
An encryption unit that encrypts the content key decrypted by the decryption unit with the license encryption key stored in the storage unit;
A content processing apparatus comprising: a license import processing unit that generates license information including the content key encrypted by the encryption unit and stores the license information in the external storage medium. The export license further includes an export counter that is an integrated value of the number of licenses assigned to the content processing device from the other content processing device.
The storage unit further imports an apparatus identifier that identifies the other content processing apparatus and an import counter that is an integrated value of the number of licenses received from the content processing apparatus identified by the apparatus identifier in association with each other. Memorize control information,
The content import key encrypted by the encryption unit only when the export counter included in the export license is larger than the import counter associated with the device identifier of the other content processing device. The content processing apparatus according to claim 6, wherein license information including the license information is generated and stored in the external storage medium. When the plurality of export licenses generated by the same content processing device are stored in the external storage medium, the content processing device acquires the export licenses in order from the smallest export counter value, and The content processing apparatus according to claim 7, wherein license information is generated. 9. The content processing apparatus further includes an interface to which the external storage medium can be connected, and executes the input / output of the export license in a state where the external storage medium is connected to the interface. The content processing apparatus according to item 1. A content sharing system for sharing content stored in an external storage medium between the first and second content processing devices,
The external storage medium includes the content encrypted with a content key, license information including the content key encrypted with a license encryption key unique to the first content processing apparatus, the first and first Device public information of each of the two content processing devices is stored,
The device public information includes a device identifier for identifying a content processing device, and a public key corresponding to a secret key assigned to the content processing device identified by the device identifier,
The first content processing apparatus
A first storage unit for storing the license encryption key;
A first content key is obtained by decrypting the encrypted content key included in the license information acquired from the external storage medium with the license encryption key stored in the first storage unit. A decryption unit;
A first encryption unit that encrypts the content key decrypted by the first decryption unit with the public key included in the device public information of the second content processing device;
An export license generation unit that generates an export license including the content key encrypted by the first encryption unit and the device identifier of the second content processing apparatus, and stores the export license in the external storage medium;
The second content processing apparatus
A second storage unit for storing a license encryption key unique to the second content processing apparatus;
The encrypted content key included in the export license including the device identifier of the second content processing apparatus acquired from the external storage medium is decrypted with the secret key assigned to the second content processing apparatus. A second decryption unit for obtaining the content key;
A second encryption unit that encrypts the content key decrypted by the second decryption unit with the license encryption key stored in the second storage unit;
A content sharing system comprising: a license import processing unit that generates license information including the content key encrypted by the second encryption unit and stores the license information in the external storage medium. In order to share content stored in an external storage medium, a content processing method for allocating a license for the content to another content processing device,
The external storage medium includes the content encrypted with a content key, license information including the content key encrypted with a license encryption key, and a plurality of contents permitted to access the external storage medium The device public information of each processing device is stored,
The device public information includes a device identifier for identifying a content processing device, and a public key corresponding to a secret key assigned to the content processing device identified by the device identifier,
The content processing method includes:
Decrypting the encrypted content key included in the license information obtained from the external storage medium with the license encryption key to obtain the content key;
An encryption step for encrypting the content key decrypted in the decryption step with the public key included in the device public information selected from the plurality of device public information;
Content including an export license generation step of generating an export license including the content key encrypted in the encryption step and the device identifier included in the selected device public information, and storing the export license in the external storage medium Processing method. A content processing method for acquiring a license for the content from another content processing device in order to share the content stored in the external storage medium,
The external storage medium includes the content encrypted with a content key, an export license including the device key for identifying itself and the content key encrypted with a public key corresponding to a secret key assigned to the device. Is remembered,
The content processing method includes:
Decrypting the encrypted content key included in the export license including the device identifier of the device acquired from the external storage medium with the assigned secret key, and obtaining the content key;
An encryption step of encrypting the content key decrypted in the decryption step with a unique license encryption key;
A license import processing step of generating license information including the content key encrypted in the encryption step and storing the license information in the external storage medium.

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