Terminal device, video recording management system, management server device, control method, and program

Abstract

A child unit (30), as a terminal device, comprises a circuit and a memory that is connected to the circuit. The circuit performs apparatus authentication with a parent unit (10), as a video recording device, using the memory, acquires an encrypted content key (Kc) from the parent unit (10), decrypts the content key (Kc) using a common key (Kp) that is shared by the parent unit (10) and the child unit (30), accesses a cloud server (20) without going through the parent unit (10), reads out content that is recorded and encrypted in the cloud server (20) by the parent unit (10), and decrypts, using the content key (Kc), and reproduces the read-out content.

Description

Terminal device, recording management system, management server device, control method, and program

[0001] The present disclosure relates to a technology used in a system that records and plays back distributed content such as a program.

[0002] A content transmission system including a content transmitting device and a content receiving device for securely transmitting and receiving content has been proposed (see, for example, Patent Document 1). In this content transmission system, the content transmitting device performs mutual authentication with the content receiving device and transfers a shared key, encrypts the content using an encryption key generated from the shared key, and transmits the encrypted content to the content receiving device. At this time, the content transmitting device switches the shared key to be transferred depending on whether the content receiving device has a predetermined security strength.

[0003] Also, a content transmission system has been proposed in which content stored in a home server is transmitted to a terminal via an external network within the scope of appropriate use (see, for example, Patent Document 2). In this content transmission system, the server permits a terminal requesting the content via remote access to transmit content that is shorter than the available playback time, and reduces the available playback time by the playback time of the content transmitted via remote access.

[0004] Patent No. 6390618 Patent No. 6187139

[0005] However, when content is recorded on a general-purpose cloud server, the content transmission systems of Patent Documents 1 and 2 have the problem that it is difficult to appropriately prevent unauthorized activities related to the content.

[0006] Therefore, the present disclosure provides a terminal device and the like that can appropriately suppress unauthorized acts related to content.

[0007] A terminal device according to one aspect of the present disclosure is a terminal device used in a recording and playback system, the recording and playback system including a cloud server device, a recording device that receives and encrypts distributed content and records the encrypted content on the cloud server device via the Internet, and the terminal device that plays back the content, the terminal device having a circuit and a memory connected to the circuit, the circuit using the memory to perform device authentication with the recording device, obtain an encrypted content key from the recording device, decrypt the content key using a shared key shared between the recording device and the terminal device, access the cloud server device without going through the recording device, read the content that has been recorded and encrypted on the cloud server device, and decrypt and play the read content using the content key.

[0008] These comprehensive or specific aspects may be realized by an apparatus, a method, an integrated circuit, a computer program, or a computer-readable recording medium such as a CD-ROM, or may be realized by any combination of an apparatus, a method, an integrated circuit, a computer program, and a recording medium. The recording medium may also be a non-transitory recording medium.

[0009] The terminal device of the present disclosure can appropriately suppress unauthorized activities related to content.

[0010] Further advantages and effects of one aspect of the present disclosure will become apparent from the specification and drawings. Such advantages and / or effects are provided by some of the embodiments and configurations described in the specification and drawings, but not all of the configurations are necessarily required.

[0011] FIG. 1 is a diagram illustrating an example of the configuration of a recording and playback system according to an embodiment. FIG. 2 is a diagram illustrating a simplified configuration of the recording and playback system according to an embodiment. FIG. 3 is a diagram illustrating an example of information held by a parent device and a management server of the recording and playback system according to an embodiment. FIG. 4 is a diagram illustrating an example of the configuration of a management server and an example of the information held by the management server according to an embodiment. FIG. 5 is a diagram illustrating an example of the configuration of a parent device and an example of the information held by the parent device according to an embodiment. FIG. 6 is a diagram illustrating another example of information held by a parent device according to an embodiment. FIG. 7 is a diagram for explaining the transfer of parent device rights according to an embodiment. FIG. 8 is a diagram illustrating an example of a data structure including content and management information according to an embodiment. FIG. 9 is a sequence diagram illustrating an example of the processing operations in the recording and playback system when an account is created for the management server and the parent device is registered according to an embodiment. FIG. 10 is a sequence diagram illustrating an example of the processing operations in the recording and playback system when a cloud account is created for the cloud server according to an embodiment. FIG. 11 is a sequence diagram illustrating an example of the processing operations in the recording and playback system when a parent device is linked to a cloud service according to an embodiment. Fig. 12 is a sequence diagram showing another example of processing operations in the recording and playback system when a parent unit is linked to a cloud service according to an embodiment. Fig. 13 is a sequence diagram showing an example of processing operations in the recording and playback system when a child unit is registered and linked to the parent unit according to an embodiment. Fig. 14 is a sequence diagram showing an example of processing operations in the recording and playback system when a parent unit records content to a cloud service according to an embodiment. Fig. 15 is a sequence diagram showing an example of processing operations in the recording and playback system when a parent unit plays content stored in a cloud service according to an embodiment. Fig. 16 is a sequence diagram showing an example of a first processing operation among the processing operations in the recording and playback system when a child unit plays content stored in a cloud service according to an embodiment. Fig. 17 is a sequence diagram showing an example of a second processing operation among the processing operations in the recording and playback system when a child unit plays content stored in a cloud service according to an embodiment.FIG. 18 is a sequence diagram showing an example of processing operations in a recording and playback system when a parent device copies content stored in a cloud service according to an embodiment. FIG. 19 is a sequence diagram showing an example of processing operations in a recording and playback system when a child device deletes its registration according to an embodiment. FIG. 20 is a sequence diagram showing an example of processing operations in a recording and playback system when a child device deletes the registration of another child device according to an embodiment. FIG. 21 is a sequence diagram showing an example of a first processing operation included in processing operations in a recording and playback system when a child device changes cloud services according to an embodiment. FIG. 22 is a sequence diagram showing an example of a second processing operation included in processing operations in a recording and playback system when a child device changes cloud services according to an embodiment. FIG. 23 is a sequence diagram showing an example of a first processing operation included in processing operations in a recording and playback system when parent device rights are transferred according to an embodiment. FIG. 24 is a sequence diagram showing an example of a second processing operation included in processing operations in a recording and playback system when parent device rights are transferred according to an embodiment. FIG. 25 is a sequence diagram showing an example of processing operations in a recording and playback system when a parent device is transferred according to an embodiment.

[0012] According to one aspect of the present disclosure, there is provided a terminal device for use in a recording and playback system, the recording and playback system including a cloud server device, a recording device that receives and encrypts distributed content and records the encrypted content on the cloud server device via the Internet, and the terminal device that plays back the content, the terminal device including a circuit and a memory connected to the circuit, the circuit using the memory to perform device authentication with the recording device, obtain an encrypted content key from the recording device, decrypt the content key using a shared key shared between the recording device and the terminal device, access the cloud server device without going through the recording device, read the content that has been recorded and encrypted on the cloud server device, and decrypt and play the read content using the content key. Note that the terminal device, the recording device, and the cloud server device are also referred to as a slave device, a master device, and a cloud server, respectively.

[0013] As a result, even when cloud recording is performed, in which a recording device records content on a cloud server, when a terminal device directly plays back content from the cloud server, the content can be fully protected, the scope of private use can be guaranteed, and users can be provided with free playback functionality. For example, playback of content from the cloud server by any terminal can be restricted. Therefore, unauthorized content-related activities can be appropriately restricted, and appropriate child device access control can be achieved.

[0014] The circuit may also obtain the shared key transmitted from the management server device to the terminal device and the recording device by performing device authentication with the recording device via the management server device.

[0015] This allows the shared key to be shared between the terminal device and the recording device through device authentication, thereby improving security.

[0016]

[0010] Also, according to one aspect of the present disclosure, there is provided a recording management system for use in a recording and playback system, the recording and playback system including a cloud server device, the recording management system receiving and encrypting distributed content, and recording the encrypted content on the cloud server device via the Internet, and a terminal device playing back the content, the recording management system including a circuit and at least one memory, the at least one memory storing validity determination information and a content key in association with the cloud server device, the circuit reading the content key from the at least one memory and using it to encrypt the content, reading the validity determination information from the at least one memory, and determining validity of the content recorded on the cloud server device using the validity determination information. For example, the recording management system may include a recording device that records the content on the cloud server device, and a management server device connected to the recording device via the Internet, the circuit and the at least one memory being provided in the recording device or the management server device, respectively. The validity determination information may be information indicating at least one of a checksum, a hash value, and the number of times the content has been copied for the management information of the content. Note that the terminal device, the recording device, the cloud server device, and the management server device are also referred to as a slave device, a master device, a cloud server, and a management server, respectively.

[0017] As a result, information related to content protection, such as validity determination information or content keys, is managed not in the cloud server device but in at least one memory of the video recording management system, which is an area inaccessible to unspecified users, while being linked to the cloud server device. Therefore, the video recording management system, i.e., the parent device or management server, manages the validity determination information (such as the checksum and hash value of the management information and the number of times each program has been dubbed) and content keys linked to the cloud server device. Therefore, even if unauthorized copies of content are created, they are treated as invalid and cannot be played, which realizes a framework. In other words, it is possible to realize appropriate measures against unauthorized copies on cloud services. Therefore, unauthorized activities related to content can be appropriately suppressed.

[0018] In addition, when the management information is stored and updated in each of the recording management system and the cloud server device, the circuit may determine the validity of the content recorded on the cloud server device by comparing the validity determination information obtained from the management information of the recording management system with the validity determination information obtained from the management information of the cloud server device.

[0019] This allows the validity determination information of the video recording management system and the validity determination information of the cloud server device to be compared, and if they are different, the content is determined to be invalid, thereby making it possible to appropriately determine the validity of the content.

[0020] According to another aspect of the present disclosure, a management server device is provided for use in a recording and playback system. The recording and playback system includes a cloud server device, a first recording device that receives and encrypts distributed content and records the encrypted content on the cloud server device via the Internet, a terminal device that plays the content, and the management server device connected to the first recording device via the Internet. The management server device includes a circuit and a memory connected to the circuit. The memory stores first identification information for identifying the first recording device in association with the cloud server device. When the first recording device is replaced with a second recording device, the circuit replaces the first identification information stored in the memory associated with the cloud server device with second identification information for identifying the second recording device, and transfers protection information stored in the first recording device, which is used to protect the content, to the second recording device. The terminal device, the recording device, and the cloud server device are also referred to as a slave device, a master device, and a cloud server, respectively. The protection information may indicate, for example, a content key, a checksum or hash value of management information, the number of dubbings, etc.

[0021] As a result, when a first recording device is replaced with a second recording device, the first identification information of the first recording device associated with the cloud server device is replaced with the second identification information of the second recording device. That is, the access right to the content of the cloud server device (also called parent device right) is transferred to the second recording device. Furthermore, the protection information stored in the first recording device is transferred to the second recording device. As a result, the transfer of the parent device, i.e., the transfer of the parent device right from the first recording device to the second recording device, can be easily performed with minimal effort while adequately protecting the content. Therefore, unauthorized content-related activities can be appropriately suppressed. Furthermore, such a transfer is considered to be within the scope of personal use and does not exceed the scope of private use. In other words, an appropriate parent device transfer can be achieved.

[0022] In addition, when the first recording device is removed from the recording / playback system, the circuit may perform at least one of the following: (a) deleting the content recorded on the cloud server device by the first recording device; (b) deleting cloud account information for accessing the cloud server device that is stored on the first recording device or in the memory; and (c) deleting the first identification information that is stored in the memory in association with the cloud account information.

[0023] This allows the deletion of content recorded on the cloud server device, the deletion (or reset) of cloud account information, etc. If the cloud account information recorded on the first recording device or the management server device is deleted (or reset), the first recording device will no longer be able to access the cloud server device. This sufficiently prevents the transferred first recording device from illegally accessing the cloud server device, and makes it easy to properly transfer the first recording device, i.e., the parent device.

[0024] The protection information is information indicating at least one of a content key for decrypting the content, a checksum for management information of the content, a hash value, and the number of times the content has been dubbed.

[0025] This allows the protection information used to effectively protect the content to be transferred from the first recording device to the second recording device, thereby increasing the strength of security and realizing an appropriate transfer of the parent unit.

[0026] Hereinafter, the embodiments will be specifically described with reference to the drawings.

[0027] The embodiments described below are all comprehensive or specific examples. The numerical values, shapes, materials, components, component placement and connection configurations, steps, and step order shown in the following embodiments are merely examples and are not intended to limit the present disclosure. Furthermore, among the components in the following embodiments, components that are not described in the independent claims that represent the highest concepts are described as optional components.

[0028] In addition, each drawing is a schematic diagram and is not necessarily an exact illustration. In addition, the same components are denoted by the same reference numerals in each drawing.

[0029] (Embodiment) FIG. 1 is a diagram showing an example of the configuration of a recording / playback system according to this embodiment.

[0030] The recording and playback system 100 in this embodiment includes a parent device 10, a cloud server 20, child devices 31, 32, and 33, and a management server 40. Although the recording and playback system 100 includes child devices 31 to 33 in FIG. 1, only one child device may be included. Furthermore, the recording and playback system 100 may include multiple parent devices 10.

[0031] The master unit 10 is configured as a receiver or a recording device that receives content, such as a program, distributed by digital broadcasting. The master unit 10 encrypts the received content using a content key Kc and records it on the cloud server 20 via the Internet.

[0032] Cloud server 20 provides cloud services to devices that access cloud server 20 via the Internet. The cloud services store encrypted content recorded by parent device 10 and transmit the content to the devices. Cloud server 20 may also be called a cloud recording server or a cloud server device.

[0033] Each of the slave devices 31 to 33 is a terminal device that accesses the cloud server 20 via the Internet and receives and plays content stored in the cloud server 20. Note that each of the slave devices 31 to 33 may be collectively referred to as a slave device 30.

[0034] The management server 40 manages the slave devices 31 to 33 and a shared key Kp shared between the master device 10 and each of the slave devices 31 to 33. The shared key Kp is also called a common key or a shared key.

[0035] The base unit 10 is installed, for example, in a home, and the base unit 10 and the slave units 31 to 33 are connected by a home network.

[0036] Specifically, the recording and reproducing system 100 performs the following processes.

[0037] For example, the management server 40 accepts new user registrations and cloud server 20 registrations from the slave device 33 via the Internet. Furthermore, the management server 40 manages the slave devices 31 to 33 by linking them with the master device 10. Furthermore, the management server 40 manages the transfer of master device rights. Transfer of master device rights is a process of transferring the master device rights, which are the function or role of the master device 10 that accesses the cloud server 20, from the original recording device to the destination recording device. Only the recording device that has this master device right functions as the master device 10 that accesses the cloud server 20. Note that, hereinafter, both a recording device that has master device rights and a recording device that does not have master device rights may be referred to as the master device 10.

[0038] Furthermore, management server 40 issues a shared key Kp to parent device 10 and each of child devices 31 to 33. For example, management server 40 transmits to parent device 10 and child device 32 the shared key Kp shared by parent device 10 and child device 32, and cloud server login information required to access cloud server 20. The cloud server login information is, for example, information such as a cloud account name and a cloud password, which will be described later.

[0039] When recording content to the cloud server 20 (i.e., a cloud service), the parent device 10 encrypts the content using the content key Kc and records the encrypted content to the cloud service. While FIG. 1 illustrates the parent device 10 recording content directly to the cloud server 20 via the network, content can also be recorded to the cloud service via the smartphone, using the smartphone as a network router (i.e., bridge) to allow the smartphone to absorb specification differences (i.e., inconsistencies) between cloud services. This eliminates the need to change the parent device 10's embedded software each time a supported cloud service is added; it can be supported simply by updating the smartphone's software. Because the parent device 10 only constantly accesses the smartphone, the parent device 10 does not need to know information about the cloud service.

[0040] Furthermore, the master device 10 encrypts the content key Kc using the shared key Kp, and transmits the encrypted content key Kc to the slave device 32 via the Internet.

[0041] The slave device 32 is registered in the management server 40 as a device linked to the parent device 10. The slave device 32 then requests the parent device 10 to play content. In response to this playback request, the slave device 32 obtains from the parent device 10 a content key Kc encrypted using a shared key Kp. The slave device 32 then decrypts the content key Kc using the shared key Kp. The slave device 32 then accesses and logs in to the cloud server 20 registered in the management server 40, and obtains the content stored in the cloud server 20. The slave device 32 then decrypts and plays back the content using the content key Kc. That is, the slave device 32 decodes the stream.

[0042] Furthermore, when the master unit 10 used in the recording and playback system 100 is replaced with another recording device, i.e., when the master unit right is transferred, for example, the slave unit 33 registers the new master unit with the management server 40. The master unit 10 transfers the content key Kc and the cloud server login information to the new master unit. The master unit 10 then deletes the content key Kc and the like.

[0043] The slave device 31 is located, for example, in a home and satisfies the cloud usage requirements. The cloud usage requirements are requirements stipulated for playing content recorded on a cloud service, and define what is required of the slave device and the master device (including the management server). That is, the slave device 31 can access the cloud server 20 via the Internet and obtain and play content stored on the cloud server 20. The slave device 32 is located, for example, outside the home and satisfies the remote viewing requirements. The remote viewing requirements are, for example, the ARIB standard, Terrestrial Digital Television Broadcasting Operational Standards ARIB TR-B14, Volume 5, Appendix C, Remote Viewing Requirements for Digital Broadcast Receivers. Furthermore, the slave device 32 satisfies the above-mentioned cloud usage requirements. That is, the slave device 32 can access the master device 10 and, if content is stored on the master device 10, can obtain and play the content. Furthermore, the slave device 32 can access the cloud server 20 via the Internet and play content stored on the cloud server 20.

[0044] Note that FIG. 1 illustrates an example of a system including a management server 40. However, as shown in FIG. 5 (described later), it is also possible to provide the functions of the management server 40 in the master device 10, or to provide some or all of the functions of the management server 40 in a slave device 30 such as a smartphone. When the functions of the management server 40 are provided in a slave device 30 such as a smartphone, the master device 10 acquires cloud service information from the slave device 30 and accesses the cloud server 20, just as in the above example. However, when the slave device 30 accesses the cloud server 20, the information is contained within the slave device 30, so no external information is acquired. This makes it suitable for playing content on the cloud server 20 from the slave device 30. However, when there are multiple slave devices 30, information cannot be shared, and each slave device 30 must store information about the cloud service, which presents a challenge. On the other hand, not providing a management server 40 offers significant benefits in terms of system load and may be considered an aspect of the present disclosure.

[0045] FIG. 2 is a diagram showing a simplified configuration of the recording / playback system 100 according to this embodiment.

[0046] As shown in FIG. 2, the parent device 10 is, for example, a recording device installed in a home, and receives content such as a program, which is digital data distributed by broadcast. The parent device 10 may output the received content as video and audio to a television receiver, or may store the content on a recording medium. Furthermore, the parent device 10 in this embodiment is connected to a cloud server 20, a child device 30, and a management server 40 via the Internet. The cloud server 20 may also be referred to as a general-purpose cloud service. Furthermore, the child device 30 may be any one of the child devices 31 to 33 shown in FIG. 1, or may be a group of multiple child devices.

[0047] In this embodiment, the content is distributed by broadcasting, but it may also be distributed via the Internet.

[0048] FIG. 3 is a diagram showing an example of information stored in the parent device 10 and the management server 40 of the recording and playback system 100. As shown in FIG.

[0049] The master unit 10 holds the number of times the content has been dubbed, the checksum of the content management information, and the content key Kc as information. For example, this information is stored in a memory provided in the master unit 10.

[0050] The number of times dubbing is the number of times that content recorded on the cloud server 20 can be dubbed.

[0051] The management information checksum is a checksum for the management information, which is information for managing content recorded on the cloud server 20. For example, when one or more pieces of content are recorded in accordance with the BDAV (Blu-ray (registered trademark) Disc Audio / Visual) standard, the management information checksum is used to determine the validity of the BDAV on the cloud server 20. In other words, the checksum is used to determine the validity of a group of content (i.e., the entire disc) recorded in accordance with the BDAV standard. The checksum is also called a management information checksum. A specific example of management information is shown in FIG. 8. Furthermore, the number of times each piece of content has been dubbed is also used to determine the validity of that content.

[0052] The content key Kc is a key used to encrypt and decrypt content recorded on the cloud server 20 .

[0053] Management server 40 holds a management list as information. For example, the management list is stored in a memory provided in management server 40. The management list is a list for managing parent device 10, child device 30, and cloud server 20, and includes, for example, account list L1, child device list L3, cloud service list L4, parent device list L5, etc., as shown in FIG.

[0054] FIG. 4 is a diagram showing an example of the configuration of the management server 40 and information stored in the management server 40. As shown in FIG.

[0055] The management server 40 includes an account management unit 41 , a shared key management unit 42 , a child device management unit 43 , a cloud service account management unit 44 , and a parent device management unit 45 .

[0056] The account management unit 41 manages an account list L1 that indicates account information L2 for each of one or more users. The account list L1 contains, for example, account information L2 for one user. The account information L2 includes a pair of the user's account name and password, and a parent / child device linking list. The parent / child device linking list indicates one or more parent / child device set information, and the parent / child device set information indicates a pair consisting of a parent device ID, a child device ID, a shared key ID, and an expiration date. In other words, each pair indicated in the parent / child device linking list is linked to the parent device ID, the child device ID, the shared key ID, and the expiration date.

[0057] The parent device ID is identification information of the parent device 10, and the child device ID is identification information of the child device 30. The shared key ID is information linked to the shared key, and is identification information of the shared key shared between the parent device 10 of the parent device ID and the child device 30 of the child device ID. The expiration date is the authentication expiration date of the child device 30 corresponding to the child device ID linked to the expiration date.

[0058] Each pair shown in the parent-child device linking list indicates the identification information of each authenticated parent device 10 and child device 30. Therefore, it can be said that the account management unit 41 manages the device authentication relationship between the parent device 10 and the child device 30 using the account information L2 shown in the account list L1.

[0059] The parent device IDs shown in each group may be different from each other or may be the same, and the number of child device IDs included in each group is not limited to one and may be multiple.

[0060] The shared key management unit 42 manages one or more shared keys Kp. Specifically, for each piece of account information L2 included in the account list L1, the shared key management unit 42 manages a shared key Kp corresponding to each of one or more shared key IDs indicated in the account information L2.

[0061] 4, the expiration date is shown in association with the slave device ID and the shared key ID in the master device-slave device linking list of the account information L2, but it does not have to be shown in the master device-slave device linking list. In this case, the shared key management unit 42 may manage the expiration date of the slave device 30 that has the shared key Kp indicated by the shared key ID for each shared key ID. In other words, the expiration date is managed as the expiration date of the shared key Kp.

[0062] The master unit management unit 45 manages a master unit list L5 that indicates information about one or more master units 10. The master unit list L5 indicates, for each of one or more master units 10 registered in the home network, the master unit ID, the IP (Internet Protocol) address, and the master unit password of that master unit 10.

[0063] The handset management unit 43 manages a handset list L3 that indicates information about one or more handset devices 30. The handset list L3 indicates, for each of one or more handset devices 30 registered in the home network, the handset ID and the IP (Internet Protocol) address of that handset device 30.

[0064] The cloud service account management unit 44 manages a cloud service list L4 that indicates the relationship between the host device 10 and cloud services. The cloud service list L4 associates information about each cloud service with information about the host device 10. The information about the cloud service includes a cloud service ID, which is identification information for the cloud service, a uniform resource locator (URL) indicating the location of the cloud service, and a cloud account name and cloud password required to use the cloud service. The information about the host device 10 includes the host device ID and the host device password.

[0065] When the parent device right is transferred as described above, the cloud service account management unit 44 updates the parent device ID in the cloud service list L4. When a cloud service is deleted or switched, the cloud service account management unit 44 also updates this cloud service list L4.

[0066] In the example of FIG. 4, management server 40 holds a management list including account list L1 and slave device list L3, but master device 10 may hold the management list.

[0067] FIG. 5 is a diagram showing an example of the configuration of base unit 10 and information stored in base unit 10. As shown in FIG.

[0068] If master unit 10 has the management list, master unit 10 includes account management unit 41, shared key management unit 42, slave unit management unit 43, and cloud service account management unit 44 instead of management server 40. In this case, the management list does not include information about master unit 10. Also, as in the example shown in FIG. 5 , if master unit 10 has the management list, it can be said that master unit 10 has the functions of management server 40. Therefore, in such a case, recording and playback system 100 does not need to include management server 40.

[0069] 5, the master device 10 is a multi-user device, and the account management unit 41 manages an account list L1 that indicates the account information L2 of each of the multiple users. Alternatively, the master device 10 may be a single-user device. In this case, the management server 40 does not have the account management unit 41 and the account list L1, but directly manages one piece of account information L2.

[0070] In the example shown in FIG. 5, the base unit 10 manages the shared key Kp, and the shared key Kp is provided to the handset 30 when the handset 30 is authenticated and can be used until the expiration date.

[0071] FIG. 6 is a diagram showing another example of information stored in the base unit 10. In FIG.

[0072] 6, the host device 10 has cloud service information L11 or L12, which is information about cloud services registered in the host device 10. Such cloud service information L11 or L12 is stored in a memory provided in the host device 10. The cloud service information L11 indicates the cloud service ID, URL, cloud account name, and cloud password of the cloud service registered in the host device 10.

[0073] On the other hand, cloud service information L12 indicates the cloud service ID of the cloud service registered by parent device 10, but does not indicate the URL, cloud account name, or cloud password. In the examples shown in Figures 9 to 25 according to this embodiment, parent device 10 has cloud service information L12 instead of cloud service information L11, and performs processing using this cloud service information L12. In this case, parent device 10 and child device 30 need to obtain the URL, cloud account name, and cloud password of the cloud service from management server 40 each time they access a cloud service.

[0074] The parent unit 10 also holds content-related information L13 indicating the number of dubbings, a checksum of management information, and a content key Kc. Specifically, the content-related information L13 indicates a cloud service ID, a checksum of management information related to the cloud service indicated by the cloud service ID, and a program management list for the cloud service.

[0075] The program management list indicates, for each program that is content recorded in the cloud service, a program ID that is identification information for that program, the number of times that program has been dubbed, and the content key Kc for that program. Note that the program ID may be, for example, the five-digit file name of the rpls file shown in Figure 8 described below.

[0076] 6, the parent device 10 has the content-related information L13, but it is also possible that all or part of this information is held by the management server 40. By holding the content-related information L13 on the management server 40 side, the content-related information L13 can be acquired from the management server 40 regardless of the power state (on / off) of the parent device 10, and direct playback from the cloud service 20 can be made possible even when the parent device 10 is powered off.

[0077] FIG. 7 is a diagram for explaining the transfer of master device rights.

[0078] When transferring parent unit rights, management server 40 rewrites the parent unit ID and parent unit password shown in cloud service list L4. At this time, the number of dubbings, content key Kc, management information checksum, and other information managed by the original parent unit 10 are transferred between the recording device that was the original parent unit 10 and the recording device at the transfer destination that is now the new parent unit 10. The transfer of parent unit rights is completed by performing two operations: the rewriting in management server 40 and the transfer between the recording devices.

[0079] Note that if the parent unit 10 has the functionality of the management server 40, i.e., if the recording / playback system 100 does not have the management server 40, the parent unit 10 has a cloud service list L4, as shown in FIG. 5 . Therefore, in addition to the number of dubbings, the content key Kc, and the checksum of the management information, the cloud service list L4 is also transferred between recording devices. However, in this example, there is a security hole because there is a possibility that the parent unit right may be illegally duplicated if the user turns off the power during a move. Therefore, a configuration in which the recording / playback system 100 has the management server 40 separate from the parent unit 10 can provide higher security than a configuration in which the parent unit 10 has the functionality of the management server 40.

[0080] Furthermore, when the master unit right is transferred, the shared key Kp and the device authentication status of the slave unit 30 may also be transferred between recording devices. However, with regard to device authentication, because the slave unit 30 also holds information about the master unit 10, the transfer cannot be completed through processing by the master unit 10 and management server 40 alone. Therefore, the shared key Kp and the device authentication status of the slave unit 30 may not be transferred, and the new master unit 10 may start the process over again from device authentication of the slave unit 30. In this case, security can be increased compared to when a transfer is performed.

[0081] FIG. 8 is a diagram showing an example of a data structure including content and management information.

[0082] For example, the cloud server 20 stores one or more contents in accordance with the data structure of the BDAV standard, as shown in Fig. 8. In this data structure, a BDAV directory is located in a root directory. The BDAV directory is the original directory of the BDAV standard. This BDAV directory contains a file "Info.bdav", a PLAYLIST directory, a CLIPINF directory, and a STREAM directory.

[0083] The file "Info.bdav" is the overall management information under the BDAV directory and includes a program list (i.e., a program list). For example, the checksum or hash value of this file "Info.bdav" is used to determine the validity of the entire BDAV directory (i.e., the entire disc described above). In other words, an example of the management information checksum described above is the checksum of the file "Info.bdav".

[0084] The PLAYLIST directory contains rpls files such as "00001.rpls." The rpls files indicate detailed information such as the program name, and also indicate the playback order (scenario) of the clpi files contained in the CLIPINF directory.

[0085] The CLIPINF directory contains clpi files such as "00100.clpi". The clpi file is content management information and indicates audio / video attribute information and a playback map table. Note that when the content key Kc is managed within the BDAV standard, it is managed in this clpi file. Content is also called a stream, stream data, or stream file.

[0086] Usually, immediately after recording of content, there is a 1:1 relationship between the files in the PLAYLIST directory and the files in the CLIPINF directory related to that content. When program combination is performed, one program (i.e., the files in the PLAYLIST directory) may refer to multiple files in the CLIPINF directory. Conversely, when program division is performed, multiple files in the PLAYLIST directory may refer to (or share) one file in the CLIPINF directory. Note that when program combination and program division are performed, the files in the CLIPINF directory and the STREAM directory are not changed, and only the files in the PLAYLIST directory are modified. Note that program combination and program division are performed in accordance with the BDAV standard.

[0087] The STREAM directory contains m2ts files such as "00100.m2ts." These m2ts files are stream data equivalent to the content. To play back the content, at least this m2ts file is required. Furthermore, of the data structure shown in FIG. 8, at least the STREAM directory containing the m2ts file must be placed in the cloud service. Furthermore, there is a 1:1 relationship between the files in the CLIPINF directory and the files in the STREAM directory. Note that, since an MPEG2 Transport stream has been used as an example, the file is referred to as M2TS; however, when a 4K broadcast is recorded, an MMT / TLV stream is recorded, and therefore the file is recorded as an MMTS file. The file name differs for each container that stores the stream, but this indicates that the stream is recorded here.

[0088] Here, the validity of the content is determined by the parent device 10, which cannot be operated by the user. The validity of the content on the cloud server 20 is determined by at least one of a first determination method and a second determination method.

[0089] The first determination method utilizes a checksum or hash value of the management information. For example, when content is recorded on the cloud server 20 in accordance with the management information structure of the BDAV standard, the above-mentioned "info.bdav" file is present, which manages the entire disc. By constantly updating the checksum of this file and continuously synchronizing it between the cloud server 20 and the parent device 10, the validity of the entire disc can be determined. In other words, the parent device 10 and the cloud server 20 each repeatedly and synchronously update the checksum of the "info.bdav" file. If the checksum updated by the parent device 10 differs from the checksum updated by the cloud server 20, the parent device 10 determines that all content managed in the "info.bdav" file on the cloud server 20 includes invalid content. In this case, the number of dubbings may be stored in the cloud server 20.

[0090] In the second determination method, the parent unit 10 manages the number of times each program has been dubbed. Each time the parent unit 10 dubs a piece of content, it reduces the number of times that content has been dubbed by one. When the number of times that content has been dubbed reaches zero, the parent unit 10 deletes the entry for that program from the program management list stored in the parent unit 10. This prevents dubbing from exceeding a specified number, even if a copy of a legitimate program is fraudulently created, the legitimate program is repeatedly dubbed, and the legitimate program on the cloud server 20 is replaced with the copy.

[0091] With only the second determination method, the number of dubbings is checked when processing of the content is actually performed, and the content is determined to be invalid based on the number of dubbings. Therefore, after the user has taken the trouble to select a program, the user is notified that the program is invalid. On the other hand, with the first determination method, it is possible to determine whether the disc is valid or invalid the moment the disc (i.e., the BDAV directory) is accessed, so that a warning panel can be quickly displayed to the user.

[0092] Furthermore, in this embodiment, the cloud server 20 stores content in a format that complies with the BDAV standard so that the slave device 30 can also directly access the cloud server 20 and play the content. In other words, the cloud server 20 stores not only the content but also management information for the content. Therefore, as long as the slave device 30 obtains the content key Kc from the master device 10 using application software (also called a viewing application) that can interpret the BDAV standard, it can execute playback processing within the slave device 30, including interpretation of the BDAV standard management information stored on the cloud server 20. However, in this embodiment, the interpretation of the management information is basically performed by the master device 10. However, if the slave device 30 implements a viewing application that interprets the management information as described above, the playback processing, including the interpretation, may be contained within the slave device 30.

[0093] On the other hand, in order to minimize the amount of information stored on the cloud server 20, only the content, which is stream data, may be stored on the cloud server 20, and the parent device 10 may hold other management information. Also, other management information may be stored in the management server 40, not in the parent device 10. In this case, if the management server 40 stores up to the content key Kc, it becomes possible to realize playback from the child device 30 completely independent of the device state of the parent device 10.

[0094] In this case, the slave device 30 queries the master device 10 to display a content list (i.e., a list of programs), select a program to be played, determine a playback position, and so on. The slave device 30 obtains the URL of the stream data (i.e., the URL of the cloud service that provides the stream data) from the master device 10, and finally, obtains the content, which is the stream data to be played, by accessing the cloud server 20. In the case of remote viewing, the master device 10 decrypts the stream data, protects it (i.e., encrypts it) using DTCP (Digital Transmission Content Protection), and delivers it to the slave device 30.

[0095] Furthermore, the method of determining the validity of content may differ between Case 1, in which the management information is stored on the cloud server 20, and Case 2, in which the management information is stored on the parent device 10. In Case 1, validity is determined using the number of times the content has been dubbed, a checksum, etc. On the other hand, in Case 2, all of the management information for the BDAV other than the stream data is stored on the parent device 10, so determining validity using such a checksum may not be necessary.

[0096] In this embodiment, the data structure of the BDAV standard is used as an example of a data structure. However, in this embodiment, any data structure may be used, not limited to the data structure of the BDAV standard, as long as the data structure has a content list, management information for each piece of content, and a stream file.

[0097] FIG. 9 is a sequence diagram showing an example of the processing operations in the recording and playback system 100 when an account is created on the management server 40 and the parent device 10 is registered.

[0098] First, the slave device 30, which may be a personal computer (also called a PC) or a smartphone (also called a smart phone), accesses the management server 40 (step S1). Then, the slave device 30 logs in to the management server 40 by specifying an account name and password to create an account (step S2).

[0099] The management server 40 adds new account information L2 to the account list L1, and records the above-mentioned specified account name and password in the account information L2 (step S3).

[0100] Meanwhile, each of the one or more base units 10 configures the home network and further configures a base unit password in response to, for example, user input operations (step S15). That is, each of the one or more base units 10 is connected to the home network and holds a device name, an IP address, and a base unit password. Note that the device name is configured by the user, but a uniquely determined base unit ID may be used instead.

[0101] The handset 30 searches for one or more base units 10 connected to the home network as candidates for the base unit 10 to be registered (step S4). Specifically, the handset 30 acquires the device name and IP address of each of the one or more base units 10 connected to the home network (step S5). The handset 30 then displays a list of the one or more base units 10 connected to the home network as a base unit candidate list (step S6). The base unit candidate list includes, for example, the device name and IP address of each of the one or more base units 10. The handset 30 then determines a base unit 10 to be registered from the base unit candidate list in response to a registration operation by the user (step S7). The handset 30 then attempts to log in to the determined base unit 10 by entering the base unit password (step S8).

[0102] The slave device 30 determines whether the login was successful through the processing of step S8 (step S9). If the slave device 30 determines that the login was unsuccessful (No in step S9), it terminates the process for registering the master device 10. On the other hand, if the slave device 30 determines that the login was successful (Yes in step S9), it logs out of the master device 10 that it logged in to in step S8 (step S10). Furthermore, the slave device 30 requests the management server 40 to register the master device 10 in the master device list L5 held by the management server 40, i.e., to register the master device ID, IP address, and master device password of the master device 10 determined in step S7 (step S11). In response to the request from the slave device 30, the management server 40 registers the master device ID, IP address, and master device password in the master device list L5 (step S12).

[0103] Next, the slave device 30 requests the management server 40 to register the master device 10 determined in step S7 in the account information L2 by specifying the master device ID and master device password of the master device 10 determined in step S7 (step S13). In response to the request from the slave device 30, the management server 40 registers the master device 10 determined in step S7 in the account information L2 as a master device 10 that can access the cloud server 20. That is, the management server 40 registers the master device ID specified by the slave device 30 in the account information L2 (step S14).

[0104] FIG. 10 is a sequence diagram showing an example of the processing operation in the recording and playback system 100 when a cloud account is created for the cloud server 20. As shown in FIG.

[0105] First, the slave device 30, which is, for example, a PC or a smartphone, requests cloud service registration processing from the management server 40 (step S21). In response to the request from the slave device 30, the management server 40 requests the slave device 30 to input information necessary for the cloud service registration processing (step S22).

[0106] The slave device 30 receives inputs such as a cloud account name, a cloud password, an email address, and payment information as information required for the cloud service registration process in response to user input operations (step S23), and then transmits the information to the management server 40 (step S24).

[0107] When management server 40 receives the above information from slave device 30, it transmits the information to cloud server 20 and requests cloud server 20 to create a cloud account (step S25). Cloud server 20 checks the information (i.e., input information) and creates a cloud account according to the content of the information (step S26). Cloud server 20 then notifies management server 40 that the cloud account has been created and the access URL (step S27).

[0108] The management server 40 adds a new cloud service ID corresponding to the cloud account created on the cloud server 20 to the cloud service list L4. Furthermore, the management server 40 registers the access URL (i.e., URL) notified by the cloud server 20 in the cloud service list L4 in association with the cloud service ID. Furthermore, the management server 40 registers the cloud account name and cloud password indicated by the information transmitted from the slave device 30 in the cloud service list L4 in association with the cloud service ID (step S28).

[0109] Then, the management server 40 notifies the slave device 30 of the completion of the cloud account creation and the cloud service ID (step S29).

[0110] Fig. 11 is a sequence diagram showing an example of the processing operation in the recording and playback system 100 when the parent device 10 and a cloud service are linked. In the example of Fig. 11, the processing operation records a cloud service ID in the parent device 10. In other words, the parent device 10 holds the cloud service information L12 shown in Fig. 6.

[0111] First, the slave device 30 determines the master device 10 that will access the cloud service in response to an input operation by the user (step S31). Then, the slave device 30 inputs a combination of the cloud service ID corresponding to the cloud service and the master device ID of the determined master device 10 to the management server 40, thereby setting the master device that will access the cloud service (step S32).

[0112] The management server 40 searches the parent unit list L5 for the parent unit ID and obtains the parent unit password associated with the parent unit ID in the parent unit list L5. The management server 40 then associates the parent unit ID and parent unit password with the cloud service ID entered in step S32 and registers them in the cloud service list L4 (step S33). This associates the parent unit 10 with the cloud service.

[0113] Meanwhile, the parent device 10 accepts an input operation by the user (step S34), activates cloud recording setting (step S35), and inputs the parent device ID to the management server 40 to inquire about available cloud services from the management server 40 (step S36).

[0114] In response to the inquiry from the parent device 10, the management server 40 searches the cloud service list L4 for an entry with the parent device ID (step S37). That is, the management server 40 searches the cloud service list L4 for a cloud service ID associated with the parent device ID. The management server 40 then transmits the searched cloud service ID to the parent device 10 (step S38). Upon receiving the cloud service ID from the management server 40, the parent device 10 adds the cloud service as a recording destination (step S39). That is, the parent device 10 records the received cloud service ID in the cloud service information L12. In the example shown in FIG. 11 , the parent device 10 queries the management server 40 for detailed information about the cloud service (e.g., URL, cloud account name, cloud password, etc.) each time it logs in to the cloud service.

[0115] After the process of step S32, the slave device 30 logs out from the management server 40 (step S40).

[0116] 12 is a sequence diagram showing another example of the processing operation in the recording and playback system 100 when the parent device 10 and a cloud service are linked. In the example of Fig. 12, the processing operation records not only the cloud service ID but also the cloud account name and cloud password in the parent device 10. In other words, the parent device 10 holds the cloud service information L11 shown in Fig. 6.

[0117] First, the recording / playback system 100 executes steps S41 to S46 similar to the steps S31 to S36 shown in FIG.

[0118] Next, in response to the inquiry from the parent device 10, the management server 40 searches the cloud service list L4 for an entry having the parent device ID entered by the parent device 10 (step S47). At this time, the management server 40 searches the cloud service list L4 for the cloud service ID, URL (i.e., cloud URL), cloud account name, and cloud password associated with the parent device ID. The management server 40 then transmits the searched cloud service ID, URL, cloud account name, and cloud password to the parent device 10 (step S48). Upon receiving the cloud service ID and other information from the management server 40, the parent device 10 adds the cloud service as a recording destination (step S49). That is, the parent device 10 records the received cloud service ID, URL, cloud account name, and cloud password in the cloud service information L11. Note that in the example shown in FIG. 12, the parent device 10 does not need to inquire of the management server 40 about detailed information about the cloud service when logging in to the cloud service.

[0119] After the process of step S42, the slave device 30 logs out from the management server 40 (step S50).

[0120] FIG. 13 is a sequence diagram showing an example of the processing operation in the recording and playback system 100 when the slave unit 30 is registered and linked to the master unit 10. In FIG.

[0121] First, the slave device 30, which is, for example, a smartphone, logs in to the management server 40 by entering an account name and password (step S51). Then, the slave device 30 transmits the slave device ID and IP address of the logged-in slave device 30 to the management server 40 so that the slave device 30 is registered (step S52).

[0122] When the management server 40 receives the slave device ID and the IP address from the slave device 30, the management server 40 registers the slave device ID and the IP address in the slave device list L3 in association with each other (step S53). Then, the management server 40 notifies the slave device 30 that the registration of the slave device 30 has been completed (step S54).

[0123] Upon receiving the notification from the management server 40, the slave device 30 acquires the master device list L5 from the management server 40 (step S55). The master device password is omitted from the master device list L5. The slave device 30 then determines a master device 10 from the master device list L5 in response to a user input operation (step S56). That is, the slave device 30 selects a master device 10 to be accessed from the slave device 30 from one or more master devices 10 listed in the master device list L5. The slave device 30 then inputs the slave device ID of the slave device 30 and the master device ID and master device password of the master device 10 determined from the master device list L5 to the management server 40, and requests the management server 40 to set up access to the master device 10 (step S57).

[0124] In response to a request from the slave device 30, the management server 40 determines whether the input master device ID and master device password are correct (step S58). Specifically, the management server 40 determines whether the master device ID and master device password are correct by performing an access check to the master device 10 using the master device ID and master device password. If the master device ID and master device password are correct, the management server 40 creates master device / slave device set information in the account information L2, thereby linking and registering the slave device 30 and the master device 10 (step S60). The master device / slave device set information associates the master device ID determined to be correct with the slave device ID of the slave device 30 that made the request to the management server 40, the shared key ID, and the expiration date of the shared key Kp. Specifically, the management server 40 sets the expiration date, generates the shared key Kp, and assigns the shared key ID to the shared key Kp. Device authentication between the master device 10 and the slave device 30 is performed through steps S57 to S60. Then, the management server 40 notifies the slave device 30 of the shared key Kp (step S61), and also notifies the master device 10 associated with the slave device 30 of the shared key Kp (step S62).

[0125] 13, the shared key Kp is notified to the slave device 30 and the master device 10 at the timing of steps S61 and S62, but may be notified at other timings. For example, when content of the cloud service is played, the master device 10 and the slave device 30 may specify the master device ID, the slave device ID, and the cloud service ID to the management server 40, respectively, and request the management server 40 to notify them of the shared key Kp.

[0126] In this embodiment, an access check to the base unit 10 is performed in step S58, but this access check does not have to be performed. However, if there is a possibility that the password for the base unit 10 will be changed, it is better to perform such an access check.

[0127] FIG. 14 is a sequence diagram showing an example of the processing operation in the recording and playback system 100 when the parent device 10 records content to a cloud service.

[0128] First, the parent device 10 accepts a user's input to start recording with the cloud service as the recording destination (step S65). Next, the parent device 10 logs in to the management server 40 using the parent device ID and parent device password of the parent device 10, and requests the URL, cloud account name, and cloud password of the cloud server 20 (i.e., the cloud service) from the management server 40 (step S66). In response to the request from the parent device 10, the management server 40 notifies the parent device 10 of the URL, cloud account name, and cloud password of the cloud server 20 (step S67).

[0129] Upon receiving the notification from management server 40, parent device 10 logs out of management server 40 (step S68) and logs in to the cloud service using the URL, cloud account name, and cloud password (step S69). Furthermore, parent device 10 requests cloud server 20 to create management information (step S70). Note that the management information may be various types of information other than the stream file (i.e., m2ts file) among the data structures shown in FIG. 8 .

[0130] Next, the parent unit 10 repeatedly executes steps S71 to S75 until recording stops. For example, steps S71 to S75 are executed for each block of broadcast content. Specifically, the parent unit 10 analyzes the broadcast content to acquire the content's attribute information, trick play map information, and other information (step S71). For example, in MPEG-2 Video, trick play map information is a management table for each GOP (Group of Pictures) that manages the address, time code, and IPIC size within the stream file. Similarly, in H.264 and H.265, trick play map information is created each time an IPIC is detected within a stream. This trick play map information is used for jump playback, trick play, and the like, and is also used to derive the start address during normal playback. Next, the parent unit 10 encrypts the stream data, which is the content, using the content key Kc (step S72). The parent unit 10 then requests the cloud server 20 to write the encrypted stream data (step S73). Furthermore, the parent device 10 updates the management information (step S74) and requests the cloud server 20 to update the management information (step S75).

[0131] When the parent device 10 receives an instruction to stop recording, for example, in response to a user input operation (step S76), it requests the cloud server 20 to close the management information (step S77). Furthermore, the parent device 10 requests the cloud server 20 to close the stream data (step S78). The parent device 10 then records the content key Kc and the number of dubbings (step S79) and logs out from the cloud server 20 (step S80).

[0132] FIG. 15 is a sequence diagram showing an example of the processing operation in the recording and playback system 100 when the parent device 10 plays back content stored in a cloud service.

[0133] First, the parent unit 10 logs in to the management server 40 by entering its parent unit ID and parent unit password (step S81). Next, the parent unit 10 enters its cloud service ID into the management server 40 and obtains from the management server 40 the cloud account name, cloud password, and URL associated with the cloud service ID (step S82). The parent unit 10 then logs in to the cloud service indicated by the URL by entering the cloud account name and cloud password (step S83). The parent unit 10 then obtains a program list, which is a list of recorded content, from the cloud service (i.e., cloud server 20) by reading it from the management information (step S84).

[0134] The parent device 10 displays the acquired program list, selects a program to be played from the program list in response to, for example, a user input operation, and starts processing to play the content of that program (step S85). That is, the parent device 10 acquires management information for the program from the cloud server 20 (step S86) and acquires a stream file name from the management information (step S87). Next, the parent device 10 searches the cloud service using the stream path, accesses the stream file with the stream file name, and opens it (step S88).

[0135] The parent unit 10 then repeatedly executes steps S89 and S90 until playback is stopped. That is, the parent unit 10 reads data from the stream file (i.e., stream data) whose size is an integer multiple of the encryption block (step S89). Next, the parent unit 10 decrypts the data in the stream file using the content key Kc and decodes the data in GOP units (step S90). Note that the encryption unit (i.e., encryption block) and the decoding unit (i.e., GOP) are different. The encryption unit is fixed length, while the decoding unit is variable length. Playback is achieved by outputting the decoded result to a monitor screen, such as a TV.

[0136] Next, the parent device 10 requests the cloud server 20 to close the stream file (step S91), and logs out from the cloud server 20 (step S92). Furthermore, the parent device 10 logs out from the management server 40 (step S93). Step S93 may be executed at this timing, or may be executed immediately after step S82.

[0137] FIG. 16 is a sequence diagram showing an example of a first processing operation among the processing operations in the recording and playback system 100 when the slave device 30 plays back content stored in a cloud service.

[0138] First, the slave device 30, which may be, for example, a smartphone, logs in to the management server 40 by entering its account name and password (step S95). The slave device 30 then enters its master device ID into the management server 40 and obtains from the management server 40 the IP address associated with the master device ID (step S96). Next, the slave device 30 logs in to the master device 10 corresponding to the master device ID and IP address by entering the master device password (step S97). Furthermore, the slave device 30 selects a cloud service to be used as the playback destination and specifies the cloud service for the master device 10 (step S98). At this time, if the master device 10 has multiple cloud services as recording destinations, the cloud services are displayed in a list alongside the internal HDD, optical disc, etc., and the user selects the cloud service to be used for playback.

[0139] The parent device 10 logs in by inputting its parent device ID and parent device password into the management server 40 (step S99). The parent device 10 then inputs its own cloud service ID into the management server 40, acquires from the management server 40 the cloud account name, cloud password, and URL associated with the cloud service ID, and logs out (step S100). The parent device 10 then logs in to the cloud server 20 corresponding to the acquired URL by inputting the acquired cloud account name and cloud password (step S101). The parent device 10 then acquires a program list from the cloud server 20 by reading the management information (step S102), and provides the cloud service ID and program list to the child device 30 (step S103).

[0140] The slave unit 30 determines a program to be played from the provided program list (step S104), specifies the determined program to the master unit 10, and requests the content key Kc of the program and the URL of the stream file from the master unit 10 (step S105).

[0141] Upon receiving the request, the parent device 10 obtains the management information for the program from the cloud server 20 (step S106). Furthermore, the parent device 10 obtains the stream file name from the management information and generates a stream path (step S107). The parent device 10 then uses the stream path to search the cloud server 20 for the stream file with the stream file name and obtains the URL for the stream file (step S108). Alternatively, the parent device 10 may generate a URL for accessing the stream file from the URL for accessing the cloud server 20. Since the procedure for this is likely to differ for each cloud service, it is sufficient to obtain information that allows access to the stream file in a manner appropriate for the server.

[0142] 17 is a sequence diagram showing an example of a second processing operation among the processing operations in the recording and playback system 100 when the slave device 30 plays back content stored in a cloud service. The second processing operation is an operation that is performed subsequent to the first processing operation.

[0143] 16, the master device 10 encrypts the content key Kc of the stream file using the shared key Kp (step S110).The master device 10 then provides the encrypted content key Kc and the URL of the stream file to the slave device 30 (step S111).

[0144] Upon acquiring the encrypted content key Kc, the slave device 30 decrypts the content key Kc using the shared key Kp (step S112). The slave device 30 then inputs the cloud service ID provided in step S103 to the management server 40 and requests the cloud account name, cloud password, and URL associated with the cloud service ID from the management server 40 (step S113). In response to the request from the slave device 30, the management server 40 provides the cloud account name, cloud password, and URL to the slave device 30 (step S114).

[0145] The slave device 30 logs in to the cloud server 20 corresponding to the provided URL by entering the provided cloud account name and cloud password (step S115). Furthermore, the slave device 30 specifies the URL of the stream file to the cloud server 20 and opens the stream file (step S116). Furthermore, the slave device 30 repeatedly executes the processes of steps S117 and S118 until playback stops. That is, the slave device 30 reads data of the stream file (i.e., stream data) whose size is an integer multiple of the encrypted block (step S117). Next, the slave device 30 decrypts the data of the stream file using the content key Kc and decodes the data in units of GOPs (step S118). The decoded results are displayed on an output device equipped to the slave device 30 to realize playback.

[0146] Furthermore, the slave device 30 closes the stream file on the cloud server 20 (step S119). Subsequently, the slave device 30 logs out from the cloud server 20 (step S120) and logs out from the parent device 10 (step S121). As a result, the parent device 10 logs out from the cloud server 20 (step S122). Then, the slave device 30 also logs out from the management server 40 (step S123).

[0147] 17, login is performed in step S115, but this login may be omitted. If the cloud server 20 is set to be accessible by anyone, login is not particularly required, and there may be cases where accessing a file via a URL allows immediate READ-ONLY access to the file. In such cases, it is possible to omit the login step.

[0148] FIG. 18 is a sequence diagram showing an example of the processing operation in the recording and playback system 100 when the parent device 10 copies content stored in a cloud service.

[0149] First, the parent unit 10 selects a disc stored in the cloud server 20 as a copy target, for example, in response to a user's input operation (step S125). Next, the parent unit 10 enters its parent unit ID and parent unit password into the management server 40 to log in (step S126). Furthermore, the parent unit 10 enters its cloud service ID into the management server 40, obtains the cloud account name, cloud password, and URL associated with the cloud service ID from the management server 40 (step S127), and logs out of the management server 40 (step S128).

[0150] Next, the parent unit 10 logs in to the cloud server 20 corresponding to the URL by entering the cloud account name and cloud password (step S129), and obtains a program list from the cloud server 20 by reading it from the management information (step S130). This program list may also be called a cloud-recorded program list or a program list. The parent unit 10 determines the content to be dubbed from the program list in response to, for example, a user's input operation, and accepts the start of dubbing to an optical disc (step S131).

[0151] The parent unit 10 then reads the management information for the program to be dubbed from the cloud server 20 (step S132) and writes the management information to an optical disc located in the parent unit 10 (step S133). The parent unit 10 then reads the stream data for the program to be dubbed from the cloud server 20 (step S134). The parent unit 10 decrypts the read stream data using a content key, encrypts it for the optical disc, and records the encrypted stream data on the optical disc (step S135). The parent unit 10 updates the number of times the program has been dubbed (also called the number of dubs) by, for example, decrementing it (step S136). If the number of dubs becomes 0 as a result of the update, the parent unit 10 deletes the content key for the program and deletes the program from the cloud service (i.e., the cloud server 20) (step S137). The parent unit 10 then logs out of the cloud server 20 (step S138).

[0152] FIG. 19 is a sequence diagram showing an example of the processing operation in the recording and playback system 100 when the slave device 30 deletes its own registration.

[0153] First, the slave device 30, which is, for example, a smartphone, logs in to the management server 40 by inputting an account name and password (step S141). Next, the slave device 30 inputs the slave device ID of the slave device 30 to the management server 40 to request slave device deletion (step S142).

[0154] In response to the request from the slave device 30, the management server 40 searches the slave device list L3 for the slave device ID of the slave device 30 to be deleted and deletes the entry containing that slave device ID (step S143). That is, the management server 40 deletes the slave device ID and the IP address associated with that slave device ID from the slave device list L3. Next, the management server 40 searches the account information L2 for master device / slave device set information containing that slave device ID and deletes the entry that is the master device / slave device set information (step S144). Then, the slave device 30 logs out of the management server 40 (step S145).

[0155] 20 is a sequence diagram showing an example of the processing operation in the recording and playback system 100 when a slave device 30 deletes the registration of another slave device 30. For example, the slave device 30 is a PC, and the other slave device 30 is a smartphone.

[0156] First, the PC logs in to the management server 40 by inputting the account name and password (step S146), and then requests the management server 40 for the slave device list L3 (step S147).

[0157] In response to the request from the PC, the management server 40 transmits the slave device list L3 to the PC (step S148). Upon receiving the slave device list L3, the PC determines the slave device 30 (i.e., smartphone) to be deleted from the slave device list L3, for example, in response to an input operation by the user (step S149). The PC then inputs the slave device ID of the determined smartphone to the management server 40 and requests the slave device to be deleted (step S150).

[0158] In response to a request from the PC, the management server 40 searches the slave device list L3 for the slave device ID of the smartphone to be deleted and deletes the entry containing that slave device ID (step S151). That is, the management server 40 deletes the slave device ID and the IP address associated with that slave device ID from the slave device list L3. Next, the management server 40 searches the account information L2 for the master device / slave device set information containing that slave device ID and deletes the entry that is the master device / slave device set information (step S152). The PC then logs out of the management server 40 (step S153).

[0159] FIG. 21 is a sequence diagram showing an example of a first processing operation included in the processing operation in the recording and playback system 100 when the slave device 30 changes cloud services.

[0160] First, the slave device 30, which is, for example, a PC, logs in to the management server 40 by inputting an account name and password (step S161), and requests the management server 40 to perform cloud service registration processing (step S162). In response to the request from the slave device 30, the management server 40 requests the slave device 30 to input information necessary for the cloud service registration processing (step S163).

[0161] The slave device 30 receives inputs of information necessary for the cloud service registration process, such as a cloud account name, a cloud password, an email address, and payment information, in response to input operations by the user (step S164), and then transmits the information to the management server 40 (step S165).

[0162] When the management server 40 receives the above information from the slave device 30, it transmits the information to the cloud server 20 and requests the cloud server 20 to create a cloud account (step S166). The cloud server 20 checks the information (i.e., the input information) and creates a cloud account according to the content of the information (step S167). The cloud server 20 then notifies the management server 40 that the cloud account has been created and provides an access URL (step S168). Upon receiving the notification from the cloud server 20, the management server 40 notifies the slave device 30 that the cloud account has been created (step S169).

[0163] When the slave device 30 receives the notification that the cloud account creation is complete, it obtains the cloud service list L4 from the management server 40 (step S170) and identifies the cloud services currently available to the slave device 30 from the cloud service list L4 (step S171). Note that the cloud password and the parent device password may be omitted from the cloud service list L4 provided to the slave device 30 (if they are managed in the management list of the parent device 10). Next, the slave device 30 obtains the IP address (i.e., the parent device IP address) associated with the parent device ID of the identified cloud service from the management server 40 (step S172).

[0164] 22 is a sequence diagram showing an example of a second processing operation among the processing operations in the recording and playback system 100 when the slave device 30 changes cloud services. The second processing operation is an operation that is performed subsequent to the first processing operation.

[0165] The slave device 30 attempts to log in to the master device 10 using the master device IP address acquired in step S172 of FIG. 21 and the master device password of the master device 10 corresponding to the master device IP address (step S175). The slave device 30 then determines whether the login was successful through the processing of step S175 (step S179). If the slave device 30 determines that the login failed (No in step S179), it terminates the processing for changing the cloud service of the slave device 30. On the other hand, if the slave device 30 determines that the login was successful (Yes in step S179), it requests the management server 40 to delete the master device ID and master device password of the master device 10 from the entry for the original cloud service (step S180). Note that the original cloud service is the cloud service identified in step S171 of FIG. 21. In other words, the slave device 30 requests the management server 40 to delete the master device ID and master device password associated with the cloud service ID of the original cloud service from the cloud service list L4.

[0166] In response to the request from the slave device 30, the management server 40 deletes the master device ID and master device password from the entry of the original cloud service (step S181).

[0167] Next, the slave device 30 requests the management server 40 to set a master device ID and a master device password in the entry for the new cloud service (step S182). In response to the request from the slave device 30, the management server 40 sets the master device ID and the master device password in the entry for the new cloud service (step S183). Note that the new cloud service is the cloud service corresponding to the cloud account created in step S167 of Fig. 21. In other words, the master device ID and the master device password are associated with the cloud service ID indicating the new cloud service in the cloud service list L4.

[0168] The slave device 30 then requests the master device 10 to delete the management information checksum, the number of dubbings, and the content key Kc associated with the original cloud service (step S184). Furthermore, the slave device 30 notifies the master device 10 of the cloud service ID of the new cloud service (step S185), and logs out from the master device 10 (step S186).

[0169] In steps S184 and S185, the slave unit 30 requests the master unit 10 to perform processing, but the management server 40 may also request the master unit 10. Also, the example of Fig. 22 does not describe processing for deleting content from the cloud server 20. This is because the content becomes unplayable data. However, since the content remains as useless data, the slave unit 30 or the management server 40 may request the cloud server 20 to delete or format the recorded program when it executes step S184.

[0170] FIG. 23 is a sequence diagram showing an example of a first processing operation among the processing operations in the recording and playback system 100 when the parent machine right is transferred.

[0171] First, the slave device 30, which is, for example, a smartphone, logs in to the management server 40 by entering an account name and password (step S191), and requests a cloud service list L4 from the management server 40 (step S192). In response to the request from the slave device 30, the management server 40 transmits the cloud service list L4 to the slave device 30 (step S193). Note that the cloud password and the master device password may be omitted from the cloud service list L4 provided to the slave device 30.

[0172] When the slave device 30 receives the cloud service list L4, it determines the cloud service (hereinafter referred to as the target cloud service) to be the target of the transfer of the master device right from the cloud service list L4, for example, in response to an input operation by the user (step S194). When the master device right is transferred, the master device 10 associated with the target cloud service is changed. Next, the slave device 30 requests the management server 40 to re-search for the master device from the home network (step S195). In response to the request from the slave device 30, the management server 40 transmits the master device list L5 to the slave device 30 (step S196). Note that the master device password is omitted from the master device list L5.

[0173] When the slave device 30 receives the master device list L5, it selects from the master device list L5 the master device 10 associated with the target cloud service (hereinafter also referred to as the source master device 10) and the master device to be newly associated with the target cloud service (hereinafter also referred to as the destination master device 10) and designates them to the management server 40. That is, the slave device 30 inputs the cloud service ID of the target cloud service, the master device ID and master device password of the source master device 10, and the master device ID and master device password of the destination master device 10 to the management server 40, and requests a change of the master device 10 (step S197).

[0174] In response to a request from the slave device 30, the management server 40 determines whether the master device ID and master device password of the master device 10 from which the transfer is to be made match the master device ID and master device password, respectively, in the entry for the cloud service to be processed (step S198). The master device ID and master device password in the entry for the cloud service to be processed are the master device ID and master device password associated with the cloud service ID of the cloud service to be processed in the cloud service list L4. If the management server 40 determines that they do not match (No in step S199), it terminates the process for transferring master device rights. If the management server 40 determines that they match (Yes in step S199), it logs in to the first master device (step S200). The first master device is the master device 10 from which the transfer is to be made.

[0175] The second master unit, which is the master unit 10 at the new location, configures the home network and sets the master unit password in response to, for example, user input (step S201). That is, the second master unit is connected to the home network and holds the master unit ID, IP address, and master unit password.

[0176] 24 is a sequence diagram showing an example of a second processing operation among the processing operations when the parent device right is transferred in the recording and playback system 100. The second processing operation is an operation that is performed subsequent to the first processing operation.

[0177] The management server 40 attempts to log in to the second master unit 10, which is the destination master unit 10, using the master unit ID and master unit password of the second master unit (step S211). The management server 40 determines whether the login was successful through the processing of step S211 (step S213). If the management server 40 determines that the login was unsuccessful (No in step S213), it terminates the processing for transferring master unit rights. On the other hand, if the management server 40 determines that the login was successful (Yes in step S213), it requests information such as a management information checksum, a content key set, and the number of dubbing attempts from the first master unit, and acquires this information from the first master unit (step S214). The content key set consists of one or more content keys Kc. Furthermore, the management server 40 requests the second master unit to write the acquired information, such as the management information checksum, the content key set, and the number of dubbing attempts, and writes this information to the second master unit (step S215).

[0178] Next, the management server 40 updates the parent device ID in the entry for the cloud service in the cloud service list L4 (step S216). That is, the management server 40 changes the parent device ID associated with the cloud service ID of the target cloud service in the cloud service list L4 from the parent device ID of the first parent device to the parent device ID of the second parent device. Furthermore, the management server 40 requests the first parent device to delete information held by the first parent device, such as the management information checksum, content key set, and number of dubbings (step S217). The management server 40 then logs out from the first parent device (step S218), logs out from the second parent device (step S219), and notifies the child device 30 that the transfer process is complete (step S220). Upon receiving the notification of the transfer process, the child device 30 logs out from the management server 40 (step S221).

[0179] FIG. 25 is a sequence diagram showing an example of the processing operation in the recording and playback system 100 when the parent device 10 is transferred.

[0180] First, the slave device 30, which is, for example, a smartphone, logs in to the management server 40 by inputting an account name and password (step S231). Next, the slave device 30 inputs the master device ID and master device password of the master device 10 to be transferred to the management server 40, and requests the management server 40 to delete the master device 10 (step S232).

[0181] In response to a request from the slave device 30, the management server 40 searches for the master device ID in the master device list L5 and identifies the master device password associated with the master device ID (step S233). The management server 40 then determines whether the identified master device password matches the master device password entered in step S232 (step S234). If the management server 40 determines that the master device passwords do not match (No in step S234), it terminates the process for transferring the master device 10. On the other hand, if the management server 40 determines that the master device passwords match (Yes in step S234), it deletes the entry for the master device ID entered in step S232 from the master device list L5. Furthermore, the management server 40 clears the master device ID from the cloud service list L4 and deletes the entry for the master device ID (i.e., master device / slave device set information) from the master device / slave device linking list in the account information L2 (step S235).

[0182] Furthermore, the parent unit 10 to be transferred resets the personal information held by that parent unit 10 in response to, for example, an input operation by the user (step S236).

[0183] (Summary of the embodiment) As described above, the slave device 30 in the present embodiment is a terminal device used in the recording and playback system 100. That is, the recording and playback system 100 includes a cloud server device that is the cloud server 20, a recording device that is the master device 10, and a terminal device that is the slave device 30. The recording device receives and encrypts distributed content, and records the encrypted content on the cloud server device via the Internet. The terminal device plays back the content. Such a terminal device includes a circuit and a memory connected to the circuit. The circuit uses the memory to perform device authentication with the recording device, acquires an encrypted content key from the recording device, decrypts the content key using a shared key shared between the recording device and the terminal device, accesses the cloud server device without going through the recording device, reads content that has been recorded and encrypted on the cloud server device, and decrypts and plays back the read content using the content key.

[0184] For example, in conventional remote viewing, both the parent device and the child device support content protection technologies such as DTCP. Furthermore, device authentication is performed between the parent device and the child device, ensuring viewing within the scope of private use. This is based on constraints imposed by a system configuration in which the parent device stores content and the content can only be played via the parent device. However, when recording content to a cloud server device (i.e., cloud recording), the content may be recorded to a general-purpose cloud server device. Such general-purpose cloud server devices may not support DTCP or other protocols, and content stored on the cloud server device can be accessed from any PC as long as the URL of the content or the cloud server device is known. Furthermore, the PC does not need to access the content via the parent device. In such a situation, the technologies described in Patent Documents 1 and 2 described above are unable to adequately protect content, guarantee the scope of private use, and provide users with free playback functionality.

[0185] However, in this embodiment, the terminal device, which is the slave device 30, performs device authentication with the recording device, which is the master device, obtains the encrypted content key Kc from the recording device, and uses the content key Kc to decrypt and play the content read from the cloud server device. Therefore, when the terminal device directly plays back content from the cloud server device, the terminal device can fully protect the content, guarantee the scope of private use, and provide the user with free playback functionality. In other words, appropriate slave device access control can be achieved.

[0186] Furthermore, in the terminal device (i.e., slave 30) in this embodiment, the circuit performs device authentication with master 10 via management server 40, thereby obtaining shared key Kp transmitted from management server 40 to slave 30 and master 10. This allows shared key Kp to be shared between slave 30 and master 10 through device authentication, thereby improving security.

[0187] The recording management system according to this embodiment is a system used in the recording and playback system 100. Specifically, the recording and playback system 100 includes a cloud server device (cloud server 20), a recording management system, and a terminal device (slave device 30). The recording management system receives and encrypts distributed content, and records the encrypted content on the cloud server device via the Internet. The terminal device plays back the content. Specifically, the recording management system includes a circuit and at least one memory, and the at least one memory stores validity determination information and a content key in association with the cloud server device. The circuit reads the content key from the at least one memory and uses it to encrypt the content, reads validity determination information from the at least one memory, and determines the validity of the content recorded on the cloud server device using the validity determination information. The recording management system may also include a recording device (master device 10) and a management server device (management server 40). Specifically, the recording management system includes a recording device that records content on the cloud server device and a management server device connected to the recording device via the Internet. In this case, the above-mentioned circuit and at least one memory are provided in the recording device or the management server device, respectively. Also, the validity determination information is information indicating at least one of a checksum for the management information of the content, a hash value, and the number of times the content has been copied.

[0188] As described in Patent Documents 1 and 2, digital data is much easier to copy and tamper with than analog data. Furthermore, when a cloud server device is used to record digital content, the cloud server device can be accessed from any device, such as a PC, making the content more susceptible to unauthorized use, such as copying. When recording content using a conventional recorder, the content and information related to content protection (such as a content key and number of dubbings) are recorded together on a hard disk drive (HDD). In such a system, a proprietary file system is used, or device-binding information is stored in an area inaccessible to users. For example, SQV (SeeQVault®) and Blu-ray® Discs (BD Discs) store information in an area requiring secure access to prevent unauthorized copying. However, when content is recorded on a cloud server device, the content can be accessed from any PC or other device, and file operations are also possible. Therefore, if the content is a file, copies of the content may be easily created. Furthermore, if the cloud server device is a general-purpose cloud server device, it is difficult to make the cloud server device compatible with secure access and the like.

[0189] Therefore, in the recording management system of this embodiment, information related to content protection is managed not in the cloud server device but in at least one of the above-mentioned memories, which are areas inaccessible to unspecified users, while being linked to the cloud server device. The information related to content protection is validity determination information or a content key. As a result, the recording management system, i.e., the parent device 10 or the management server 40, manages the validity determination information (such as the checksum and hash value of the management information and the number of dubbings per program) and content key linked to the cloud server device. This enables a framework to be realized in which even if unauthorized copies of content are created, they are treated as invalid and cannot be played. In other words, appropriate measures against unauthorized copies can be implemented on cloud services.

[0190] The validity determination information may be a flag for determining the validity of the content.

[0191] In addition, in the recording management system of this embodiment, when management information is stored and updated in both the recording management system and the cloud server device, the circuit of the recording management system determines the validity of the content recorded on the cloud server device by comparing the validity determination information obtained from the management information of the recording management system with the validity determination information obtained from the management information of the cloud server device. As a result, the validity determination information of the recording management system is compared with the validity determination information of the cloud server device, and if, for example, they differ, the content is determined to be invalid. As a result, the validity of the content can be appropriately determined.

[0192] Furthermore, the management server 40 in this embodiment is a management server device used in the recording and playback system 100. That is, the recording and playback system 100 includes a cloud server device (cloud server 20), a first recording device (master device 10), a terminal device (slave device 30), and a management server device (management server 40). The first recording device receives and encrypts distributed content, and records the encrypted content on the cloud server device via the Internet. The terminal device plays back the content. The management server device is connected to the first recording device via the Internet. Such a management server device includes a circuit and a memory connected to the circuit. The memory stores first identification information for identifying the first recording device in association with the cloud server device. When the first recording device is replaced with a second recording device, the circuit replaces the first identification information stored in the memory in association with the cloud server device with second identification information for identifying the second recording device, and transfers protection information stored in the first recording device, which is used to protect the content, to the second recording device. The protection information indicates, for example, a content key, a checksum or hash value of management information, the number of times of dubbing, and the like.

[0193] Even in the past, there were functions for transferring and dubbing recorded programs between recorders. However, such transfer of recorded programs required the transfer of the recorded programs themselves, since the recorded programs were stored on the recorder's built-in HDD or on a device-bound USB (Universal Serial Bus) HDD. Applying this conventional method to cloud recording, which records content on a cloud server 20, would require the recorded program data to be first read from the cloud server 20, decrypted, and encrypted for transmission and reception via DTCP, then decrypted again at the transfer destination, encrypted with local encryption, and recorded on the built-in HDD, etc., resulting in a lot of work. In other words, since the target of transfer is the recorded program itself, and the recorded program is stored on the recorder, the recorded program itself must be transferred. This is extremely time-consuming.

[0194] However, in cloud recording, if we consider that the data (i.e., the recorded programs) are stored on the cloud server 20, it is not necessarily necessary to move the recorded programs; it is sufficient if the access rights to the recorded programs on the cloud server 20 and the information indicating the validity of the data (i.e., the protection information) can be moved.

[0195] Therefore, as described above, when the first recording device is replaced with the second recording device, the management server device in this embodiment replaces the first identification information of the first recording device associated with the cloud server device with the second identification information of the second recording device. That is, the access rights to the content of the cloud server device are transferred to the second recording device. Furthermore, the management server device transfers the protection information held in the first recording device to the second recording device.

[0196] This allows the transfer of the parent unit 10, i.e., the transfer of parent unit rights from the first recording device to the second recording device, to be easily performed while fully protecting the content and saving time. Furthermore, such a transfer is considered to be within the scope of personal use and does not go beyond the scope of private use. In other words, it is possible to realize an appropriate transfer of the parent unit 10.

[0197] Furthermore, when the first recording device is removed from the recording and playback system 100, the circuitry of the management server device in this embodiment executes at least one of the following: (a) deleting content recorded on the cloud server device by the first recording device; (b) deleting cloud account information for accessing the cloud server device, which is stored in the first recording device or memory; and (c) deleting first identification information associated with the cloud account information and stored in memory. For example, in (b), cloud service information L11 or L12 shown in FIG. 6 is deleted as cloud account information. Alternatively, in (b), the cloud service ID, URL, cloud account name, and cloud password in the cloud service list L4 shown in FIG. 4 or 5 are deleted as cloud account information. In (c), the parent device ID in the cloud service list L4 shown in FIG. 4 is deleted as first identification information.

[0198] Even with conventional recorders, when transferring a recorder to another person, it is recommended to reset personal information and format the HDD. However, for recorders that support cloud recording, this alone is not sufficient; it is also necessary to prohibit access to recorded programs on the cloud service or delete recorded programs from the cloud service. If the user forgets to perform these procedures, the processing of the transferred recorder may go beyond the scope of personal use.

[0199] Therefore, in this embodiment, as described above, content recorded on the cloud server device is deleted, and cloud account information is deleted (or reset). If the cloud account information recorded on the first recording device or the management server device is deleted (or reset), the first recording device will no longer be able to access the cloud server device. Furthermore, if the management server device manages the cloud service list L4, access from the first recording device can also be prevented by logging in to the management server device from a smartphone, PC, or the like and deleting the entry in the cloud service list L4. Therefore, it is possible to sufficiently prevent the transferred first recording device from accessing the cloud server device illegally, and it is possible to easily achieve appropriate transfer of the first recording device, i.e., the parent device.

[0200] In this disclosure, managing information means storing the information, and may also mean changing or deleting the information.

[0201] In addition, the protection information in this embodiment is information indicating at least one of the content key Kc for decrypting the content, the checksum for the content management information, the hash value, and the number of times the content has been copied. This allows the protection information used to effectively protect the content to be transferred from the first recording device to the second recording device, thereby increasing security and enabling the parent unit 10 to be moved appropriately.

[0202] (Other Aspects, etc.) While systems, devices, etc. according to one or more aspects of the present disclosure have been described above based on the embodiments, the present disclosure is not limited to those embodiments. As long as the modifications do not deviate from the spirit of the present disclosure, various modifications conceivable by those skilled in the art to the above embodiments may also be included in the present disclosure.

[0203] The following cases are also included in this disclosure:

[0204] (1) The at least one device is specifically a computer system comprising a microprocessor, ROM (Read Only Memory), RAM (Random Access Memory), a hard disk unit, a display unit, a keyboard, a mouse, etc. A computer program is stored in the RAM or hard disk unit. The at least one device achieves its function when the microprocessor operates in accordance with the computer program. Here, the computer program is composed of a combination of multiple instruction codes that indicate commands to the computer to achieve a predetermined function.

[0205] (2) Some or all of the components constituting at least one of the above devices may be configured as a single system LSI (Large Scale Integration). A system LSI is an ultra-multifunctional LSI manufactured by integrating multiple components on a single chip, and specifically, is a computer system configured to include a microprocessor, ROM, RAM, etc. A computer program is stored in the RAM. The system LSI achieves its functions by the microprocessor operating in accordance with the computer program.

[0206] (3) Some or all of the components constituting at least one of the above devices may be configured as an IC card or a standalone module that can be attached to or detached from the device. The IC card or module is a computer system configured with a microprocessor, ROM, RAM, etc. The IC card or module may include the above-mentioned ultra-multifunctional LSI. The IC card or module achieves its functions when the microprocessor operates in accordance with a computer program. This IC card or module may be tamper-resistant.

[0207] (4) The present disclosure may be embodied as the methods described above, a computer program for implementing these methods on a computer, or a digital signal comprising the computer program.

[0208] The present disclosure may also be a computer program or a digital signal recorded on a computer-readable recording medium, such as a flexible disk, a hard disk, a CD (Compact Disc)-ROM, a DVD, a DVD-ROM, a DVD-RAM, a BD (Blu-ray (registered trademark) Disc), a semiconductor memory, etc. Alternatively, the present disclosure may be a digital signal recorded on such a recording medium.

[0209] The present disclosure may also be applied to transmitting a computer program or digital signal via a telecommunications line, a wireless or wired communication line, a network such as the Internet, data broadcasting, or the like.

[0210] Furthermore, 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, so that the program or digital signal may be implemented by another independent computer system.

[0211] The present disclosure can be applied to, for example, a recording and playback system that records and plays back content such as a program.

[0212] REFERENCE SIGNS LIST 10 Parent device (recording device) 20 Cloud server (cloud server device) 30, 31, 32, 33 Child device (terminal device) 40 Management server 41 Account management unit 42 Shared key management unit 43 Child device management unit 44 Cloud service account management unit 45 Parent device management unit 100 Recording and playback system Kp Shared key Kc Content key L1 Account list L2 Account information L3 Child device list L4 Cloud service list L5 Parent device list L11, L12 Cloud service information L13 Content-related information

Claims

1. A terminal device for use in a recording and playback system, The recording and reproducing system includes: A cloud server device; a recording device that receives and encrypts distributed content, and records the encrypted content on the cloud server device via the Internet; the terminal device that reproduces the content, The terminal device a circuit and a memory coupled to the circuit, The circuit uses the memory to: Performing device authentication with the recording device; obtaining an encrypted content key from the recording device via the Internet; decrypting the content key using a shared key shared between the recording device and the terminal device; accessing the cloud server device without going through the recording device, and reading the content recorded and encrypted in the cloud server device; decrypting the read content using the content key and playing it; Terminal device.

2. The circuit comprises: performing device authentication between the recording device and the management server device and thereby obtaining the shared key transmitted from the management server device to the terminal device and the recording device; The terminal device according to claim 1 .

3. A recording management system for use in a recording and playback system, comprising: The recording and reproducing system includes: A cloud server device; the recording management system receiving and encrypting distributed content, and recording the encrypted content in the cloud server device via the Internet; a terminal device that acquires an encrypted content key via the Internet, decrypts the content key, and plays back the content; The video recording management system includes: a circuit and at least one memory; The at least one memory includes: storing validity determination information and the content key in association with the cloud server device; The circuit comprises: reading the content key from the at least one memory and using it to encrypt the content; reading the validity determination information from the at least one memory, and determining validity of the content recorded in the cloud server device using the validity determination information; Recording management system.

4. The video recording management system includes: a recording device that records the content on the cloud server device; a management server device connected to the recording device via the Internet, Each of the circuit and the at least one memory is provided in the recording device or the management server device. The video recording management system according to claim 3.

5. The validity determination information is The information indicates at least one of a checksum, a hash value, and the number of times the content has been copied for the management information of the content.

5. The video recording management system according to claim 3 or 4.

6. When the management information is stored and updated in each of the recording management system and the cloud server device, The circuit comprises: By comparing the validity determination information obtained from the management information of the video recording management system with the validity determination information obtained from the management information of the cloud server device, determining the validity of the content recorded in the cloud server device; The video recording management system according to claim 5.

7. A management server device for use in a recording and playback system, The recording and reproducing system includes: A cloud server device; a first recording device that receives and encrypts distributed content, and records the encrypted content on the cloud server device via the Internet; a terminal device for reproducing the content; the management server device is connected to the first recording device via the Internet; The management server device a circuit and a memory coupled to the circuit, The memory includes: storing first identification information for identifying the first recording device in association with the cloud server device; The circuit comprises: When the first recording device is replaced with a second recording device, replacing the first identification information associated with the cloud server device and stored in the memory with second identification information for identifying the second recording device; transferring protection information, which is used to protect the content and is held in the first recording device, to the second recording device; Management server device.

8. The circuit comprises: When the first recording device is removed from the recording and reproducing system, (a) deleting the content recorded in the cloud server device by the first recording device; (b) deleting cloud account information for accessing the cloud server device, the cloud account information being stored in the first recording device or the memory; and (c) deleting the first identification information stored in the memory in association with the cloud account information; Executing at least one of the following: The management server device according to claim 7.

9. The protection information is the content key for decrypting the content, a checksum for management information of the content, a hash value, and information indicating at least one of the number of times the content has been copied; The management server device according to claim 8.

10. A control method performed by a terminal device used in a video recording and playback system, comprising: The recording and reproducing system includes: A cloud server device; a recording device that receives and encrypts distributed content, and records the encrypted content on the cloud server device via the Internet; the terminal device that reproduces the content, In the control method, Performing device authentication with the recording device; obtaining an encrypted content key from the recording device via the Internet; decrypting the content key using a shared key shared between the recording device and the terminal device; accessing the cloud server device without going through the recording device, and reading the content recorded and encrypted in the cloud server device; decrypting the read content using the content key and playing it; Control methods.

11. A control method performed by a recording management system used in a recording and playback system, comprising: The recording and reproducing system includes: A cloud server device; the recording management system receiving and encrypting distributed content, and recording the encrypted content in the cloud server device via the Internet; a terminal device that acquires an encrypted content key via the Internet, decrypts the content key, and plays back the content; In the control method, storing validity determination information and the content key in association with the cloud server device; reading the content key from memory and using it to encrypt the content; reading the validity determination information from the memory, and determining the validity of the content recorded in the cloud server device using the validity determination information; Control methods.

12. A control method performed by a management server device used in a recording and playback system, comprising: The recording and reproducing system includes: A cloud server device; a first recording device that receives and encrypts distributed content, and records the encrypted content on the cloud server device via the Internet; a terminal device for reproducing the content; the management server device is connected to the first recording device via the Internet; In the control method, storing first identification information for identifying the first recording device in association with the cloud server device; When the first recording device is replaced with a second recording device, replacing the first identification information associated with the cloud server device and stored in a memory with second identification information for identifying the second recording device; transferring protection information, which is used to protect the content and is held in the first recording device, to the second recording device; Control methods.

13. A program for a terminal device used in a recording and playback system, The recording and reproducing system includes: A cloud server device; a recording device that receives and encrypts distributed content, and records the encrypted content on the cloud server device via the Internet; the terminal device that reproduces the content, The program is Performing device authentication with the recording device; obtaining an encrypted content key from the recording device via the Internet; decrypting the content key using a shared key shared between the recording device and the terminal device; accessing the cloud server device without going through the recording device, and reading the content recorded and encrypted in the cloud server device; decrypting the read content using the content key and playing it; A program for causing a computer of the terminal device to execute the above steps.

14. A program for a recording management system used in a recording and playback system, The recording and reproducing system includes: A cloud server device; the recording management system receiving and encrypting distributed content, and recording the encrypted content in the cloud server device via the Internet; a terminal device that acquires an encrypted content key via the Internet, decrypts the content key, and plays back the content; The program is storing validity determination information and the content key in association with the cloud server device; reading the content key from memory and using it to encrypt the content; reading the validity determination information from the memory, and determining the validity of the content recorded in the cloud server device using the validity determination information; A program for causing a computer of the recording management system to execute the above steps.

15. A program for a management server device used in a recording and playback system, The recording and reproducing system includes: A cloud server device; a first recording device that receives and encrypts distributed content, and records the encrypted content on the cloud server device via the Internet; a terminal device for reproducing the content; the management server device is connected to the first recording device via the Internet; The program is storing first identification information for identifying the first recording device in association with the cloud server device; When the first recording device is replaced with a second recording device, replacing the first identification information associated with the cloud server device and stored in a memory with second identification information for identifying the second recording device; transferring protection information, which is used to protect the content and is held in the first recording device, to the second recording device; A program for causing a computer of the management server device to execute the above-mentioned steps.

16. A terminal device for use in a recording and playback system, comprising: The recording and reproducing system includes: A cloud server device; a recording device that receives and encrypts distributed content, and records the encrypted content on the cloud server device via the Internet; the terminal device that reproduces the content, The terminal device a circuit and a memory coupled to the circuit, The circuit uses the memory to: Performing device authentication with the recording device; The encrypted content key is obtained from a management server device via the Internet; decrypting the content key using a shared key shared between the recording device and the terminal device; accessing the cloud server device without going through the recording device, and reading the content recorded and encrypted in the cloud server device; decrypting the read content using the content key and playing it; Terminal device.