JP6332280B2 - Content transmission apparatus, content transmission method, and computer program - Google Patents

Description

  The technology disclosed in the present specification relates to a content transmission apparatus, a content transmission method, and a computer program that encrypt and transmit content using a key shared according to a predetermined mutual authentication and key exchange (AKE) algorithm such as DTCP.

  The digitized content is relatively easy to perform illegal operations such as copying and falsification. In particular, in remote access, there is a need for a mechanism for preventing unauthorized use involved in content transmission, that is, copyright protection, while allowing the use of personal or home content. As an industry standard technique regarding transmission protection of digital contents, there is DTCP (Digital Transmission Content Protection) developed by DTLA (Digital Transmission Licensing Administrator).

  In DTCP, an authentication protocol between devices at the time of content transmission and a transmission protocol for encrypted content are decided. To summarize, the DTCP compliant device does not send out compressed content that is easy to handle in an unencrypted state outside the device, and the key exchange required to decrypt the encrypted content is a predetermined mutual authentication. And the key exchange (Authentication and Key Exchange: AKE) algorithm, and limiting the range of devices that perform key exchange using the AKE command.

  DTCP was originally defined for content transmission on a home network using IEEE 1394 or the like as a transmission path. For example, in Digital Living Network Alliance (DLNA) that regulates the interconnection of different types of information devices in the home, DTCP is used for encrypted transmission of compressed content. Recently, in DLNA, a movement to distribute digital contents stored in a home via an IP (Internet Protocol) network has become serious. Accordingly, development of DTCP + (hereinafter referred to as DTCP +) incorporating a remote access function based on DTCP-IP (DTCP mapping to IP), in which the DTCP technology is ported to an IP network, is in progress.

  For example, when viewing broadcast content, movies, and other commercial content stored on a home server from a remote location using a mobile sink device such as a mobile phone or a multi-function terminal, it is not used beyond the scope of private use. It is desired to control so that

  The current DTCP-IP (DTCP-IP Volume 1 Specification Revision 1.4) registers remote access to a server in the home with the intention of restricting the use of content by a third party. It is limited to the terminal that has been. In addition, when registering a terminal with a server in the home, a round trip time (RTT) of a command is limited to a maximum of 7 milliseconds and an upper limit of the number of hops of the IP router is imposed.

  For example, in the AKE procedure at the time of remote access, the above-mentioned restrictions on RTT and TTL are released to enable key sharing for remote access, while pre-registration to the server of the remote access terminal, remote content A proposal has been made on a content transmission system that restricts remote access from an unspecified number of users by imposing restrictions on the number of access usage and the number of key supply (for example, see Patent Document 1). ).

  However, according to the current DTCP-IP standard, if the terminal is registered only once in the home server, the content in the home server is permanently used by remote access without performing registration again thereafter. can do. For this reason, once a third party's terminal is registered in the server, the third party can use the content in the home server permanently thereafter.

JP 2011-82952 A

  The purpose of the technology disclosed in this specification is to transmit content stored in a home via an external network within a range of appropriate use while following a predetermined mutual authentication and key exchange algorithm such as DTCP. It is an object to provide an excellent content transmission apparatus, content transmission method, and computer program.

The present application has been made in consideration of the above problems, and the technology according to claim 1
A content acquisition unit that acquires content to be provided to the terminal, or a content recording unit that records content to be provided to the terminal;
A terminal providing a content and a terminal management unit for managing the playable time of the content in the terminal;
A content provider that controls transmission of content to the terminal based on the playable time;
It is the content transmission apparatus which comprises.

  According to the technique described in claim 2 of the present application, the content transmission device according to claim 1 further includes an authentication and key sharing unit that authenticates the terminal according to a predetermined mutual authentication and key exchange procedure and shares an exchange key. I have. The content providing unit is configured to provide the terminal with the content encrypted using the exchange key.

  According to the technology described in claim 3 of the present application, the authentication and key sharing unit of the content transmission device according to claim 2 is mutually connected with the terminal according to an authentication and key exchange (AKE) algorithm defined by DTCP-IP. Authentication and exchange key sharing are performed, and the terminal registration unit is configured to register a terminal according to a procedure defined by DTCP-IP.

  According to the technology described in claim 4 of the present application, the terminal management unit of the content transmission device according to claim 1 registers a terminal in a home network, and the content providing unit is a registered terminal Only in response to the access from the external network, the content is provided.

  According to the technology described in claim 5 of the present application, the terminal management unit of the content transmission device according to claim 4 is configured to give an initial value of the reproducible time to the terminal at the time of registration.

  According to the technology described in claim 6 of the present application, the terminal management unit of the content transmission device according to claim 4 is configured to reset the reproducible time of the terminal to be re-registered to the initial value. .

  According to the technique described in claim 7 of the present application, the content providing unit of the content transmitting device according to claim 4 is configured to permit transmission of the content until the reproducible time of the terminal becomes zero. ing.

  According to the technique described in claim 8 of the present application, when the content providing unit of the content transmitting apparatus according to claim 7 terminates or stops the transmission of the content, the reproduction time of the transmitted content is reproduced by the terminal. It is configured to be subtracted from the possible time.

  According to the technology described in claim 9 of the present application, the content providing unit of the content transmission device according to claim 4 determines the content shorter than the reproducible time from the reproducible time of the transmission destination terminal. After being subtracted, it is configured to transmit to the terminal.

  According to the technique described in claim 10 of the present application, the content providing unit of the content transmitting apparatus according to claim 9 reproduces the content transmitted from the length of the content when transmission of the content is terminated or stopped. The value obtained by subtracting the time is added to the reproducible time of the transmission destination terminal.

  According to the technology described in claim 11 of the present application, the content providing unit of the content transmission device according to claim 4 is configured to permit movement of the content having a shorter playback time to the terminal.

  According to the technology of claim 12 of the present application, the content providing unit of the content transmission device of claim 11 is configured to subtract the length of the moved content from the playable time of the destination terminal. ing.

  According to the technology described in claim 13 of the present application, the terminal management unit of the content transmission device according to claim 4 is configured to delete registration of a terminal whose playable time has become zero.

  According to the technique described in claim 14 of the present application, the content providing unit of the content transmitting apparatus according to claim 1 notifies the terminal of the providing destination of the current playable time when providing the content. It is configured.

  According to the technique described in claim 15 of the present application, the content transmission device described in claim 1 further includes a content information providing unit that provides the terminal with information related to the content that can be provided to the terminal. The content providing unit is configured to provide the content selected through the content information viewed on the terminal side.

  According to the technique described in claim 16 of the present application, the content information providing unit of the content transmitting apparatus according to claim 15 controls the provision of the content information based on the current reproducible time of the provision destination terminal. It is configured as follows.

  According to the technology described in claim 17 of the present application, the content information providing unit of the content transmitting device according to claim 15 provides content information of content longer than the current reproducible time of the terminal of the providing destination. Configured to restrict.

  According to the technique described in claim 18 of the present application, the content information providing unit of the content transmitting apparatus according to claim 15 is configured to limit provision of content information to a terminal having a current playable time of zero. Has been.

Moreover, the technology described in claim 19 of the present application is:
A content acquisition step of acquiring content to be provided to the terminal, or a content recording step of recording content to be provided to the terminal;
A terminal management step for managing a terminal that provides the content and a playable time of the content in the terminal;
A content providing step of controlling transmission of content to the terminal based on the playable time;
Is a content transmission method.

In addition, the technique described in claim 20 of the present application is:
A content acquisition unit for acquiring content to be provided to the terminal, or a content recording unit for recording content to be provided to the terminal,
A terminal that provides content, and a terminal management unit that manages the content reproducible time in the terminal;
A content providing unit that controls transmission of content to the terminal based on the playable time;
As a computer program written in a computer-readable format to make the computer function.

  The computer program according to claim 20 of the present application defines a computer program written in a computer-readable format so as to realize predetermined processing on a computer. In other words, by installing the computer program according to claim 20 of the present application on a computer, a cooperative operation is exhibited on the computer, and the same effect as the content transmission device according to claim 1 of the present application is obtained. be able to.

  According to the technology disclosed in the present specification, it is possible to transmit content stored in a home via an external network within an appropriate range of use while following a predetermined mutual authentication and key exchange algorithm such as DTCP. An excellent content transmission apparatus, content transmission method, and computer program can be provided.

  According to the technology disclosed in this specification, a content transmission device functioning as a source gives a predetermined reproducible time to a remotely accessed sink, and limits the content provided at the time of remote access within the reproducible time. As a result, it is possible to solve the disadvantage of the content provider that the content is viewed permanently even in a remote place.

  In addition, the effect described in this specification is an illustration to the last, and the effect of this invention is not limited to this. In addition to the above effects, the present invention may have additional effects.

  Other objects, features, and advantages of the technology disclosed in the present specification will become apparent from a more detailed description based on the embodiments to be described later and the accompanying drawings.

FIG. 1 is a diagram schematically illustrating a configuration example of a content transmission system 100 to which the technology disclosed in this specification is applied. FIG. 2 is a diagram schematically illustrating another configuration example of the content transmission system 200 to which the technology disclosed in this specification is applied. FIG. 3 is a diagram schematically illustrating a functional configuration of the content transmission apparatus 300 that operates as the servers 101 and 201 in FIGS. 1 and 2. FIG. 4 is a diagram schematically showing a functional configuration of the content receiving apparatus 400 that operates as the terminals 102 and 202 in FIGS. 1 and 2. FIG. 5 is a diagram showing a procedure for registering a sink device that performs remote access in a source device together with a reproducible time. FIG. 6 is a flowchart showing a processing procedure for the source device to register the sink device in which the sink-ID and the playable time are paired. FIG. 7 is a diagram exemplifying registered contents of a remote sink registry in which a sink-ID and a playable time are stored as a pair. FIG. 8 is a diagram schematically showing a procedure for performing content transmission by remote access between a source device and a sink device. FIG. 9 is a diagram schematically showing the contents of the content list browsing phase (SEQ 801). FIG. 10 is a diagram showing details of the contents of the RA-AKE procedure phase (SEQ802). FIG. 11 is a diagram showing a state where the remote access exchange key K _R generated for the sink device and the exchange key label K _R — label thereof are stored as RAC records in association with the sink-ID. FIG. 12 is a flowchart showing the procedure of the maintenance process of the remote sink registry. Figure 13 is a diagram schematically showing the contents of a content transmission phase for transmitting encrypted (SEQ803) using the exchange key K _R for remote access. FIG. 14 is a flowchart showing a procedure of content output management processing executed in SEQ1302 during streaming. FIG. 15 is a flowchart showing a procedure of content output control and playable time management processing performed in SEQ1304 during streaming. FIG. 16 is a flowchart showing a modification of the procedure of the content output management process performed in SEQ 1302 during streaming. FIG. 17 is a flowchart showing a procedure of content output control and playable time management processing corresponding to FIG. FIG. 18 is a flowchart showing the procedure of content output management processing executed in SEQ1302 in content movement (MOVE). FIG. 19 is a flowchart showing a procedure of content output control and playable time management processing executed in SEQ1304 in content movement (MOVE). FIG. 20 is a flowchart showing a processing procedure for restricting provision of CDS information based on the limit date and time of a sink device that is remotely accessed by the source device. FIG. 21 is a diagram illustrating a mechanism in which the source device notifies the sink device of the reproducible time in the content transmission phase. FIG. 22 is a flowchart showing a processing procedure for the sink device to display the reproducible time notified from the source device. FIG. 23 is a diagram illustrating a configuration example of a personal computer 2400 that can operate as the server 201 or a DTCP Source device. FIG. 24 is a diagram illustrating a configuration example of a recorder 2500 that can operate as the server 201 or the DTCP Source device. FIG. 25 is a diagram illustrating a configuration example of a NAS (Network Attached Storage) 2600 that can operate as the server 201 or a DTCP Source device. FIG. 26 is a diagram showing a configuration of a computer program distribution system 2700.

  Hereinafter, embodiments of the technology disclosed in this specification will be described in detail with reference to the drawings.

A. System Configuration FIG. 1 schematically shows a configuration example of a content transmission system 100 to which the technology disclosed in this specification is applied. The illustrated content transmission system 100 includes a server 101 and a terminal 102 installed in a home network 110 installed in a home. In the figure, for simplification, only one server and one terminal are depicted, but it is assumed that two or more servers and terminals are installed on the home network. For example, the server and the terminal can transmit contents by operating according to a protocol defined in DLNA.

  The server 101 is a device that provides content to the terminal 102. The server 101 is, for example, a NAS (Network Attached Storage) such as a set top box, a recorder, a television receiver, a personal computer, or a network hard disk. The server 101 obtains broadcast content received or recorded by terrestrial digital broadcasting, commercial content such as a movie read from a recording medium (not shown) such as a Blu-ray disc, and a content server (not shown) on the Internet. The content is provided to the terminal 102. Examples of forms for providing content include streaming and content movement (MOVE).

  The terminal 102 is a device that requests content from the server 101 via the home network 110, and corresponds to a multifunctional mobile terminal such as a mobile phone, a smartphone, or a tablet.

  In this embodiment, DTCP technology is applied to content transmission between the server 101 and the terminal 102 via the home network 110. Accordingly, the terminal 102 can request content stored in the server 101 after mutual authentication with the server 101 and sharing a key in accordance with a predetermined mutual authentication and key exchange (AKE) algorithm. The server 101 encrypts and transmits the requested content using the shared key. The server 101 that provides content corresponds to a DTCP source device, and the terminal 102 that uses the content corresponds to a DTCP sink device.

  When the terminal 102 wants to access the server 101 from outside the home network 110 such as a place where the user is away from home, the terminal 102 needs to be registered in the server 101 in advance in the home network 110. In the present embodiment, the server 101 gives the terminal 102 to be registered the content reproducible time allowed at the time of remote access. Details of this point will be given later. .

  FIG. 2 schematically shows another configuration example of the content transmission system 200 to which the technology disclosed in this specification is applied. The illustrated content transmission system 200 includes a server 201 installed in a home network 210 installed in a home and a terminal 202 connected on an external network 220 such as the Internet. The home network 210 and the external network 220 are interconnected via the router 230 according to the IP protocol. In the figure, for simplicity, only one server and one terminal are depicted, but two or more servers are installed in the home network 210, and there are terminals in the home network 210. It is also assumed that two or more terminals are connected on the external network 220.

  The server 201 is a NAS (Network Attached Storage) such as a set top box, a recorder, a television receiver, a personal computer, or a network hard disk. The server 201 provides broadcast content, commercial content, and the like to the terminal 202 that is remotely accessed from the external network 220. Examples of forms for providing content include streaming and content movement (MOVE).

  The terminal 202 is a multi-function mobile terminal such as a mobile phone, a smartphone, or a tablet, and requests content from the server 201 via the IP network including the home network 210 and the external network 220.

  In the present embodiment, DTCP-IP technology is applied to content transmission between the server 201 and the terminal 202 via the home network 210 and the external network 220. Therefore, the terminal 202 needs to be registered in advance in the server 201 in the home network 210 (described above). The terminal 202 can request content stored in the server 201 after mutual authentication with the server 201 and sharing of the exchange key via the IP network including the home network 210 and the external network 220. The server 201 encrypts and transmits the content requested from the registered terminal 202 using the shared exchange key. The server 201 that provides content corresponds to a DTCP source device, and the terminal 202 that uses the content corresponds to a DTCP sink device.

  In the present embodiment, the server 202 gives a content reproducible time allowed at the time of remote access to the terminal 202 registered in advance. In addition, when the pre-registered terminal 202 accesses remotely, the server 201 restricts the provision of content according to the remaining playable time. The details of this point will be described later.

  FIG. 3 schematically illustrates a functional configuration of the content transmission apparatus 300 that operates as the servers 101 and 201 (that is, the source device) in FIGS. 1 and 2. Specific examples of the servers 101 and 201 include NAS (Network Attached Storage) such as a set top box, a recorder, a television receiver, a personal computer, and a network hard disk.

  The communication / control unit 301 controls the communication operation via the home network and the external network, and controls the overall operation of the content transmission apparatus 300. In addition, the communication / control unit 301 is used for connecting external devices such as HDMI (registered trademark) (High Definition Multimedia Interface), MHL (registered trademark) (Mobile High-Definition Link), USB (Universal Serial Bus), or the like. For digital output), and can be connected to a recording / playback device such as a hard disk device or a Blu-ray disk device.

  The content recording unit 302 records content to be provided to the terminals 101 and 201 via the home network and the external network. Each content recorded in the content recording unit 302 holds a recording date and time, an access date and time, and a duration under the management of a general file system. The content recording unit 302 also records metadata of each content or content group.

  The content acquisition unit 303 acquires content to be provided to the terminals 101 and 201 from the outside via the communication / control unit 301 and records the content in the content recording unit 302 as necessary. The content acquisition unit 303 may acquire content to be provided to the terminals 101 and 201 from the content recording unit 302.

  The content acquisition unit 303 includes a terrestrial digital broadcast tuner, for example, and acquires broadcast content. In this case, the content acquisition unit 303 is based on specifications defined by, for example, ARIB (Association of Radio Industries and Businesses). The content acquisition unit 303 includes, for example, a reception function for all or part of a broadcast channel segment, an EPG (Electronic Program Guide) function (program search, program information display, program reservation), HDCP (High-bandwidth Digital Content), and the like. A copy control function based on the (Protection) specification and the like, a content protection function for encrypting a broadcast content when it is limitedly received or when the received broadcast content is externally output, and the like.

  When the servers 101 and 201 are network access servers, the content acquisition unit 303 acquires the content recorded by the recorder and the content played back by the media playback device via the network without receiving the broadcast wave. Then, it is recorded in the content recording unit 302 as necessary.

  The content acquisition unit 303 includes a media playback device such as a Blu-ray disc, and reads commercial content such as movies from the media. The content acquisition unit 303 includes a browser and downloads paid or free content from a content server (not shown) on the Internet.

  In response to a request from the terminal, the content providing unit 304 provides the content acquired by the content acquisition unit 303 to the terminal. When a terminal requests content by remote access from an external network, the terminal must be registered in advance in the terminal management unit 307. The content providing unit 304 transmits the content to the terminal using, for example, an HTTP (Hype Text Transfer Protocol) protocol. As a method of providing content, content streaming and content movement (MOVE) can be cited. The content providing unit 304 encrypts the content to be transmitted using the exchange key shared with the terminal by the authentication / key sharing unit 306.

  For example, in response to a request from the terminal, the content list providing unit 305 provides the terminal with a list of contents that can be provided to the terminal and detailed information. As can be seen from the above, the content that the servers 101 and 201 can provide to the terminal includes broadcast content received by the content acquisition unit 303, commercial content read from the media, and content already recorded in the content recording unit 302. . For providing the content list, for example, a content directory service (CDS) function that distributes the content list and the detailed information of the content in a hierarchy, which is formulated in UPnP (Universal Plug and Play) which is the base of DLNA, is applied. Is done.

The authentication / key sharing unit 306 shares the exchange key for mutual authentication and content encryption according to the authentication and key exchange (AKE) algorithm defined by the DTCP-IP with the terminal that requests the content. Do. Authentication and key sharing unit 306 for the terminal coming requesting content by remote access from the external network, and share the exchange key K _R for remote access (see below).

  The terminal management unit 307 manages information on a terminal that requests content. The terminal management unit 307 performs registration processing in advance on a terminal that uses content by remote access from an external network, and information on the terminal is “remote sink registry” or “RAC (Remote Access Connection) registry”. Manage as.

  In this embodiment, when registering a terminal, the terminal management unit 307 gives the terminal a reproducible time for content allowed at the time of remote access, and manages the paired information with the terminal identification information. There is one feature. Then, when the registered terminal remotely accesses, the content providing unit 304 updates the reproducible time of the terminal (subtraction of the reproducible time according to the content reproducible time) and the remaining Restrict the provision of content according to the playable time. However, details of this point will be given later.

  Note that the functional blocks 303 to 307 can also be realized as application programs executed on the upper level of the operating system or TCP / IP protocol in the communication / control unit 301. In addition, this type of application program can be distributed at a predetermined download site over a wide area network such as the Internet, and is a multi-function such as a digital broadcasting tuner, a TV receiver (CE) device such as a TV receiver, a smartphone, etc. It is downloaded to the terminal for use.

  Such a download site includes, for example, a server 2710 having a storage device 2711 for storing a computer program and a communication device 2712 that accepts the download in response to receiving a download request for the computer program ( The computer program distribution system 2700 is configured together with a client device (DTCP_Source or DTCP_Sink) that installs the downloaded computer program. This type of server further includes an information notification device 2713 for notifying information indicating the name of the computer program in response to a download request for the computer program from the client. The information notification device 2713 notifies information indicating that it is an application that provides commercial content recorded in the home to a remote terminal, together with the name of the computer program.

  FIG. 4 schematically illustrates a functional configuration of the content receiving apparatus 400 that operates as the terminals 102 and 202 (that is, sinks) in FIGS. 1 and 2. Specific examples of the terminals 102 and 202 are multi-function mobile terminals such as mobile phones, smartphones, and tablets.

  The communication / control unit 401 controls the communication operation via the home network and the external network, and controls the overall operation of the content receiving apparatus 400.

  The content list browsing unit 402 makes a content list acquisition request to the servers 101 and 201 serving as the sources, and displays the acquired content list browsing screen. For example, when a list of contents that can be provided by the servers 101 and 201 is acquired as CDS information (described above), a contents list screen is displayed. The user of the terminal can select content to be reproduced and output through this list screen.

  The content acquisition unit 403 transmits a content acquisition request to the servers 101 and 201 to acquire content in the server. For example, the content acquisition unit 403 requests acquisition of content selected by the user in the content list screen displayed by the content / list browsing unit 402. For example, an HTTP protocol is used for content acquisition requests to the servers 101 and 201 and content acquisition (described later). Examples of a method for acquiring content include content streaming and content movement (MOVE). In the present embodiment, when accessing the server 201 remotely, there is one feature in that the acquisition of content is limited according to the remaining playable time given at the time of registration, but details thereof will be given later. .

  The content acquired from the servers 101 and 201 is encrypted using the exchange key shared with the servers 101 and 201 by the authentication / key sharing unit 406. The content decrypting unit 404 decrypts the encrypted content acquired from the servers 101 and 201 using this encryption key. Then, the content reproduction output unit 405 reproduces and outputs the decrypted content. The content reproduction output unit 405 includes a display unit that displays content such as a moving image.

An authentication / key sharing unit 406 performs mutual authentication and encryption for content encryption with the servers 101 and 201 as content request destinations according to an authentication and key exchange (AKE) algorithm defined by DTCP-IP. Share keys. Authentication and key sharing unit 406, between the server 201 to request the content by remote access from the external network, and share the exchange key K _R for remote access. The authentication / key sharing unit 406 performs registration for remote access to the server 201 in advance while connected to the home network 210. The present embodiment is characterized in that when the terminal 202 registers with the server 201, a content reproducible time allowed at the time of remote access is given. Details of this point will be described later.

  The functional blocks 402 to 406 can also be realized as application programs executed on the upper level of the operating system or TCP / IP protocol in the communication / control unit 401. This type of application program can be distributed on a predetermined download site over a wide area network such as the Internet, and downloaded to a multifunction terminal that plays back content in a home server such as a smartphone. The

  Such a download site includes, for example, a server 2710 having a storage device 2711 for storing a computer program and a communication device 2712 that accepts the download in response to receiving a download request for the computer program ( The computer program distribution system 2700 is configured together with a client device (DTCP_Source or DTCP_Sink) that installs the downloaded computer program. This type of server further includes an information notification device 2713 for notifying information indicating the name of the computer program in response to a download request for the computer program from the client. The information notification device 2713 notifies information indicating that, for example, the commercial content recorded in the home is an application that is permitted to be viewed at a remote place, together with the name of the computer program.

  As a usage form of the content transmission system 200 shown in FIG. 2, a terminal 202 such as a mobile phone or a multi-function mobile terminal is connected to a server 201 in a home from a remote location via an external network 220 and a router 230. It is conceivable to view content recorded in the content recording unit 302 of 201 (for example, recorded broadcast content). This type of usage has the advantage that the user can view the content anywhere, while the content provider has the disadvantage that the content can be viewed permanently even at a remote location.

  For example, for broadcasters, broadcast content is viewed permanently by residents outside the broadcast area. As a result, there are concerns that the broadcasting business of local stations may be adversely affected and content may be viewed in places that are not covered by the content procurement contract.

  Therefore, in the technology disclosed in this specification, the content reproducible time allowed at the time of remote access is given to the terminal 202, and the server 201 provides the content to the terminal 202 only within the reproducible time range. , Making it impossible to permanently use content from remote locations.

  For example, the server 201 also adds a reproducible time when registering the terminal 202 for remote access. Of course, the server 201 may give the reproducible time to the terminal 202 by another method or at another time.

  When the server 201 performs content stream transmission to the terminal 202, the server 201 reduces the reproducible time by the replay time of the transmitted content, and prevents further transmission when the remaining reproducible time becomes zero. Further, when the server 201 moves the content to the terminal 202 (MOVE), the server 201 subtracts the length of the content from the reproducible time so that when the remaining reproducible time becomes zero, it cannot be transmitted any more. To do. As a method for preventing transmission, in addition to a method for confirming that the remaining playable time is zero, there is a method for deleting registration of the terminal 202.

  In this way, by restricting the provision of content to the terminal 202 by the server 201 according to the reproducible time, it is possible to prevent the content from being viewed permanently on the remotely accessed terminal 202. A user living in the broadcast target area can view the content only during the given reproducible time during a trip or business trip. At the same time, it is possible to prevent a user who lives in an area not covered by broadcasting from viewing the content permanently.

  The registration of the terminal 202 with the server 201 is possible only within the home network 210 and cannot be performed from a remote location. For example, DTCP standard Remote Sink Registration processing is performed.

  Further, the terminal 202 can return the reproducible time to the initial value by re-registering with the server 201 before the reproducible time becomes zero.

  The server 201 may notify the terminal 202 of the remaining playable time. For example, information on the reproducible time may be stored in a header field of an HTTP (Hyper Text Transfer Protocol) message when performing content transmission (described later).

B. Registration Procedure FIG. 5 illustrates a procedure for registering a sink device that performs remote access to a source device together with a reproducible time (remote sink registration processing). In the figure, it is understood that the sink device corresponds to the terminal 202 and the source device corresponds to the server 201. The registration procedure is performed only within the home network 210 and cannot be performed from a remote location.

  First, an AKE procedure is performed between a source device and a sink device under the restriction of RTT (Round Trip Time) (SEQ501). For example, if the source device and the sink device are in the home network 210, the RTT restriction is cleared and the AKE procedure ends successfully. Since the RTT-AKE procedure itself is not directly related to the gist of the technique disclosed in this specification, a detailed description thereof is omitted here.

  When the RTT-AKE procedure is successfully completed, the sink device transmits the command RA_REGISTER. Using CMD, the user's own Sink-ID is transmitted to the Source device (SEQ502).

  Here, the Sink device transmits its own Device ID or IDu as the Sink-ID (the Sink device implements the Common Device Key and the Common Device Certificate, and the Device ID becomes the specific information of the Sink. If not, IDu is used as the Sink-ID).

  On the other hand, the Source device has RA_REGISTER. Whether the sink-ID received by the CMD matches the device ID or IDu received by the RTT-AKE procedure completed immediately before, is not yet stored in the remote sink registry, and whether the remote sink registry is not full. To check. Then, when these conditions are cleared and the sink-ID is additionally stored in the remote sink registry, the source device is connected to the RA_REGISTER. The RSP is returned to the sink device (SEQ503).

  The above-described procedures SEQ501 to 503 are basically based on the DTCP specifications, for example, DTCP Volume 1 Supplement E Mapping DTCP to IP, Revision 1.4ed1 (Informational Version) V1SE. It is carried out as described in section 10.7.1.

  Then, the source device performs registration of the sink device paired with the playable time (SEQ504).

  FIG. 6 shows, in the form of a flowchart, a procedure for registering a sink device in which the source device pairs the sink-ID and the reproducible time in the procedure SEQ504.

  The Source device is RA_REGISTER. It is checked whether or not the sink-ID of the sink device that has requested registration by CMD has already been stored in the remote sink registry (managed by the terminal management unit 307) (step S601).

  If the sink-ID received from the sink device is stored (Yes in step S601), the source device sets the playable time of the sink device to the initial value (step S602), and ends this processing routine. To do. If the sink-ID has been registered before the current registration process, the reproducible time is reset to the initial value in this process.

  On the other hand, when the sink-ID of the sink device that requests registration is not stored in the remote sink registry (No in step S601), the source device ends this processing without doing anything.

  FIG. 7 exemplifies the registered contents of a remote sink registry that stores a sink-ID and a reproducible time as a pair. In the illustrated example, as indicated by reference numeral 701, the reusable time of a sink device having a sink-ID of 0x800000e924 is 43200 minutes. The minutes are registered.

  However, the management of the reproducible time information for each terminal as shown in FIG. 7 is not performed individually by the server 201 in the home network 210, but is centralized by a management server placed on the cloud or the like. You may make it carry out.

C. Limiting remote access based on reproducible time As described above, when registering the terminal 202, the server 201 gives a reproducible time of content allowed at the time of remote access and makes a pair with the Sink-ID. to manage. When the server 201 performs content stream transmission to the terminal 202, the server 201 reduces the reproducible time by the replay time of the transmitted content, and prevents further transmission when the remaining reproducible time becomes zero. Further, when the server 201 moves the content to the terminal 202 (MOVE), the server 201 subtracts the length of the content from the reproducible time so that when the remaining reproducible time becomes zero, it cannot be transmitted any more. To do. Further, as a method for preventing transmission, it is also possible to delete the registration of the terminal 202 (delete from the remote sink registry).

  As described above, the server 201 restricts the provision of the content to the terminal 202 based on the reproducible time, so that it is possible to prevent the terminal 202 that is remotely accessed from viewing the content permanently. A user living in the broadcast target area can view the content only during the given reproducible time during a trip or business trip. At the same time, it is possible to prevent a user residing in a non-broadcasting area from permanently viewing the broadcast content.

  FIG. 8 schematically shows a procedure for performing content transmission by remote access between the source device and the sink device after the above registration. In the figure, it is understood that the sink device corresponds to the terminal 202 and the source device corresponds to the server 201.

In the illustrated content transmission, the remote access exchange key is implemented by performing a mutual authentication and key exchange procedure between the source device and the sink device, and a content list browsing phase (SEQ801) for designating the content that the sink device requests to transmit. and K share _R RA-AKE procedure phase (SEQ802), has been the content specified in the content list view phase, consisting of the content transmission phase for transmitting encrypted (SEQ803) using the exchange key K _R for remote access .

  FIG. 9 schematically shows the contents of the content list browsing phase (SEQ801). In the figure, it is understood that the sink device corresponds to the terminal 202 and the source device corresponds to the server 201.

  From the sink device, a content list browsing request is issued from the content list browsing unit 402 (SEQ901).

  For browsing the content list, a CDS function formulated by UPnP, which is a DLNA base, can be applied. In this case, in SEQ901, a CDS: Browse action is issued from the sink device. Then, the source device distributes the content list and the detailed information of the content in a hierarchy.

  The browse request for the content list includes a Sink-ID that identifies the sink device. As a means for sending a Sink-ID by a CDS: Browse request, it is conceivable to newly provide a header field (for example, SinkID.dtcp.com) and send it as an HTTP header part as a parameter. On the source device side, the reproducible time of the sink device can be checked based on the sink-ID included in the request.

  On the source device side, in response to the CDS: Browse action being issued, the content list providing unit 305 acquires all content information that can be acquired by the content providing unit 304 (SEQ 902). ), A sufficient amount of CDS information is generated (SEQ903). The content that can be provided by the content providing unit 304 is, for example, broadcast content or commercial content that can be acquired by the content acquisition unit 303, or content that is already recorded in the content recording unit 302 that is its own storage. Then, the Source device returns a CDS Result to the Sink device (SEQ904).

  Note that the source device may remove content whose duration is not enough for the current playable time of the requesting sink device from the content list. Further, when the source device provides the content list, the source device may notify information on the current playable time of the requesting sink device or information on the playable time after the content is acquired.

  On the sink device side, the content list browsing unit 402 analyzes the received CDS Result and displays the content information including the title of the content and more detailed information (SEQ905).

  The user of the sink device can select content to be reproduced from the displayed content list. When the content is selected, transmission of the content from the source device to the sink device is started. Before the content transmission, mutual authentication and key exchange for remote access between the sink device and the source device, that is, RA-AKE processing is performed.

  FIG. 10 shows details of the contents of the RA-AKE procedure phase (SEQ802). In the figure, it is understood that the sink device corresponds to the terminal 202 and the source device corresponds to the server 201. The illustrated procedure is basically the same as the V1SE. The information described in Section 10.7.2 shall be followed.

The sink device transmits a CHALLENGE command including the exchange key field in which the bit for the remote access exchange key K _R (Remote Exchange Key) is set, and requests the AKE process from the source device (SEQ1001). . Then, the challenge / response portion of the authentication procedure is executed between the source device and the sink device (SEQ1002 to 1004).

However, when the CHALLENGE bits for a remote access command exchange key K _R is not set, Source device aborts the RA-AKE procedure, it is possible to continue the AKE procedure other than RA-AKE.

  The source device can receive a device ID or IDu as a sink-ID from the sink device in a challenge / response procedure (SEQ1005).

  Here, the source device performs the maintenance of the remote sink registry, that is, the process of deleting the sink-ID from which the playable time has become zero from the remote sink registry (SEQ1006). By deleting the sink-ID from which the reproducible time has become zero from the remote sink registry, it is possible to prevent the broadcast content from being permanently viewed by residents outside the broadcast target area. It is assumed that after the remote sink registration maintenance process is performed, only entries for which the remaining reproducible time remains are left. Details of the maintenance process of the remote sink registry performed in SEQ1006 will be described later.

  Note that the maintenance process of the remote sink registry has an effect of creating an area in which a new sink can be registered in the remote sink registry. However, as shown in the processing described later, content transmission to a sink device with a reproducible time of zero can be prevented without performing this processing. Therefore, this processing may not be performed when it is desired to maintain registration. If the maintenance process is not performed, although not shown, the reusable time of the sink device that is performing the RA-AKE procedure is checked. If it is zero, the AKE_CANCEL command is transmitted, and the RA-AKE procedure is performed. Discontinue. On the other hand, if it is not zero, the following processing is performed.

  Next, the source device checks whether or not the received sink-ID is registered in the remote sink registry managed in its own terminal management unit 307 (SEQ1007).

  If the Sink-ID is not listed in the remote sink registry (No in SEQ1007), the Source device transmits an AKE_CANCEL command to the Sink device (SEQ1015), and cancels the RA-AKE procedure (SEQ1016).

  On the other hand, when the sink-ID is already registered in the remote sink registry (YES in SEQ1007), the source device determines whether or not a RAC record (described later) corresponding to the sink-ID already exists. Next, the inside of the RAC registry is checked (SEQ1008).

If there is a RAC record corresponding to the sink-ID (YES in SEQ1008), the source device uses the remote access exchange key K _R and the exchange key label K _R _label stored in the RAC record. Decide on. Alternatively, if the source device does not transmit content using the remote access exchange key K _R , the source device refers to the inside of the RAC record and updates the stored values of K _R and K _R _label. You may make it (SEQ1014).

If the sink-ID has already been registered in the remote sink registry, but the corresponding RAC record does not exist (NO in SEQ1008), the source device determines whether the count value RACC for counting the RAC record is less than RACC _max . Is checked (SEQ1009). Here, RACC _max is a counter that counts remote access connections, and is initialized to zero when there is no remote access connection.

When the RACC is not less than the RACC _max (NO in SEQ1009), the source device transmits an AKE_CANCEL command to the sink device (SEQ1015), and cancels the RA-AKE procedure (SEQ1016).

If RACC is less than RACC _max (SEQ1009 of Yes), Source device, after incrementing by 1 the value of the RACC (SEQ1010), according to a predetermined calculation rule, exchange key K _R and exchange key label for remote access K and generates an _R _label (SEQ1011), these in association with Sink-ID of the Sink device, and stores the RAC record in RAC registry (SEQ1012). The server 201 manages the RAC record in the terminal management unit 307, for example.

FIG. 11 shows a state in which the remote access exchange key K _R generated for the sink device and the exchange key label K _R — label thereof are stored as RAC records in association with the sink-ID. In the illustrated example, a remote access exchange key 0x7f4130de0a6100e257cf68db and its exchange key label 0xe9 are assigned to a sink device having a Sink-ID of 0x800000e924.

The source device includes the remote access exchange key K _R extracted from the existing RAC record and its exchange key label K _R _label (including the updated case), or the newly generated remote access exchange key K _R and The exchange key label K _{R —} label is transmitted to the sink device (SEQ1017).

Source device if it supports RA_MANAGEMENT function, to initiate K _R for survival timer for maintaining the replacement K _R for remote access, for holding at least one minute K _R (SEQ1013).

  FIG. 12 shows a maintenance process procedure of the remote sink registry in the form of a flowchart. In the following, for the sake of convenience, the description will be made assuming that the maintenance process of the remote sink registry is performed in the server 201 as the source device. This maintenance process is performed, for example, by the authentication / key sharing unit 306 in the server 201 during the RA-AKE procedure phase.

  In the remote sink registry managed in the terminal management unit 307, the source device can be played back as a pair stored with the sink-ID for a sink device whose playable time has not been confirmed (No in step S1201). The time is referenced (step S1202), and it is checked whether or not the reproducible time is zero (step S1203). Then, the source device deletes the sink-ID entry whose playable time is zero (Yes in step S1203) from the remote sink registry (step S1204).

  Next, the source device repeatedly executes the processes of steps S1202 to S1204 for all the sink entries registered in the remote sink registry (Yes in step S1201).

  The maintenance process of the remote sink registry shown in FIG. 12 is not performed individually by each server 201 (in other words, performed in units of the home network 210 in which the server 201 is installed), but a management server on the cloud, etc. Thus, the remote sink registry of the server 201 in each home may be centrally managed.

  Further, the maintenance process of the remote sink registry as shown in FIG. 12 is not sequentially performed during the RA-AKE procedure, but the server 201 or a management server on the cloud (whether or not to execute the RA-AKE procedure). (Despite this) it may be done periodically.

  Also, in FIG. 12, the replayable time confirmation process is executed for all entries in the remote sink registry in one maintenance process, but the Sink-ID that is the target of the RA-AKE procedure. It is also possible to perform confirmation processing of the playable time only for the entry corresponding to.

Figure 13 is the content of the content transmission phase for transmitting encrypted using the exchange key K _R for remote access (SEQ803) schematically shown. In the figure, it is understood that the sink device corresponds to the terminal 202 and the source device corresponds to the server 201. The illustrated sequence includes a content output management process based on the reproducible time, a content output control process and a reproducible time management process.

The sink device acquires the remote access exchange key K _R acquired by the RA-AKE procedure and its exchange key label K _{R —} label, and then, for example, by an HTTP request (HTTP GET request) using an HTTP GET method. The device is requested to transmit content (SEQ1301). At the time of the request, along with the URL (Uniform Resource Locator) of the content, and sends the label K _R _label the ID of the exchange key K _R for remote access. We define a header field for sending ID (K _R _label) of the exchange key to the Source device from Sink device.

  Upon receiving the content transmission request from the sink device, the source device executes content output management processing based on the playable time (SEQ1302).

Source device in RA-AKE procedure, when sending the exchange key K _R and exchange key label K _R _label for remote access to the Sink device stores a RAC record in association with these Sink-ID (See above and FIG. 11). Therefore, the source device can check the sink-ID of the requesting sink device from the RAC record corresponding to the exchange key label K _R _label included in the content request.

  Also, the source device stores the playable time (initial value) as a pair with the sink-ID when the sink device is registered, that is, when the sink-ID is registered in the remote sink registry (see the above and FIG. 7). The source device updates the reproducible time in the remote sink registry every time the sink device uses content (described later). Therefore, the current playable time of the sink device can be checked based on the sink-ID obtained from the RAC record.

  The source device permits the content request from the sink device if the requestable sink device has a reproducible time remaining, but permits the content request from the sink device if the reproducible time is zero. do not do.

When the source device permits the content request from the sink device, the remote device extracts the remote access exchange key K _R specified by the exchange key label K _R _label from the RAC record and encrypts the content using this. Then, it is transmitted to the sink device as an HTTP response (HTTP GET response) (SEQ1303).

  When the source device starts encrypted transmission of content to the sink device, the source device subsequently executes content output control based on the playable time and management processing of the playable time of the sink device (SEQ1304).

  As a form in which the source device provides content to the sink device, streaming transmission and content movement (MOVE) can be cited. Depending on whether streaming transmission or content movement (MOVE) is performed, the content output management executed in SEQ1302 and the content output control and playable time management processing executed in SEQ1304 are different.

  FIG. 14 shows, in the form of a flowchart, the procedure of content output management processing performed in SEQ1302 during streaming. Hereinafter, for the sake of convenience, description will be made assuming that the server 201 as the source device performs, for example, the content output management process by the content providing unit 304.

The source device refers to the exchange key label K _R — label included in the content request (HTTP GET request) (step S1401), and determines whether the RAC record of the same exchange key label K _R — label exists in the terminal management unit 307. Check (step S1402).

Here, if there is no RAC record of the same exchange key label K _R — label (No in step S1402), the request source sink device may not be performing the RA-AKE procedure, and the content may be invalid. is there. Therefore, the Source device skips all subsequent processes and ends this processing routine.

On the other hand, when the RAC record of the same exchange key label K _R _label exists (Yes in Step S1402), the Source device acquires the Sink-ID corresponding to the exchange key label K _R _label from the RA record ( Step S1403).

  Next, the source device acquires the reproducible time stored as a pair with the sink-ID from the remote sink registry in the terminal management unit 307 (step S1404). However, when the reproducible time of each Sink-ID is entrusted to, for example, a management server on the cloud, the source device accesses the management server via the communication / control unit 301 and sets the corresponding reproducible time. Get information.

  Also, the source device sets the timer to zero (step S1405).

  Then, the source device checks whether or not the reproducible time of the content request source sink device is greater than zero (step S1406).

  When the playable time is not zero (Yes in step S1406), the source device permits a content request from the sink device. In other words, the source device starts measuring the timer (step S1407), and transmits the requested content by, for example, HTTP GET response (step S1408).

  On the other hand, when the reproducible time is zero (No in step S1406), the source device does not permit the content request from the sink device, skips the subsequent processing, and ends this processing routine.

  FIG. 15 is a flowchart showing the procedure of content output control and playable time management processing executed in SEQ 1304 during streaming. In the following, for the sake of convenience, description will be made assuming that, for example, the content providing unit 304 performs content output control and playable time management processing in the server 201 as the source device.

  The source device checks whether or not the timed timer value is less than the playable time of the content transmission destination sink device (step S1501).

  If the timer value is less than the reproducible time (Yes in step S1501), the process returns to step S1501 until the content transmission is terminated or stopped (No in step S1502), and the source device Continue checking the value.

  When the content transmission is completed or stopped (Yes in step S1502), the source device stops counting the timer (step S1503), and subtracts the timer value from the reproducible time of the content transmission destination sink device ( Step S1504), this processing routine ends.

  When the timer value is equal to or longer than the reproducible time (No in step S1501), the source device stops transmitting the content to the content transmission destination sink device (step S1505). Then, the server 201 sets the playable time of the sink device managed by the remote sink registry to zero (step S1506), and ends this processing routine.

  FIG. 16 shows a modification of the content output management process performed in SEQ1302 during streaming. FIG. 17 shows the procedure of content output control and playable time management processing executed in SEQ 1304 during streaming, corresponding to FIG. 16 and 17 are processing procedures intended to reduce the processing load on the source device side.

  First, the content output management process performed in SEQ1302 during streaming will be described with reference to FIG.

The source device refers to the exchange key label K _R — label included in the content request (HTTP GET request) (step S1601), and determines whether or not the RAC record of the same exchange key label K _R — label exists in the terminal management unit 307. Check (step S1602).

Here, when there is no RAC record of the same exchange key label K _R — label (No in step S1602), the request source Sink device is not performing the RA-AKE procedure, and it is an illegal content request. is there. Therefore, the Source device skips all subsequent processes and ends this processing routine.

On the other hand, when the RAC record of the same exchange key label K _R _label exists (Yes in step S1602), the Source device acquires the Sink-ID corresponding to the exchange key label K _R _label from the RA record ( Step S1603).

  Next, the source device acquires the reproducible time stored as a pair with the sink-ID from the remote sink registry in the terminal management unit 307 (step S1604). However, when the reproducible time of each Sink-ID is entrusted to, for example, a management server on the cloud, the source device accesses the management server via the communication / control unit 301 and sets the corresponding reproducible time. Get information.

  Further, the source device sets the timer to zero (step S1605).

  Then, the source device checks whether or not the reproducible time of the content transfer destination sink device is equal to or longer than the length (duration) of the content requesting the transfer (step S1606).

  When the reproducible time of the content transfer destination sink device is equal to or longer than the content length (duration) (Yes in step S1606), the source device permits the content request from the sink device. In this case, after subtracting the content length (duration) from the reproducible time of the content transfer destination sink device (step S1607), the source device starts counting the timer (step S1608), and Transmission is performed by, for example, HTTP GET response (step S1609). As will be described later (see FIG. 22), when the reproducible time is notified to the sink device, the reproducible time before subtracting the length of the content is passed.

  On the other hand, if the playable time is smaller than the content duration (No in step S1606), the source device does not permit the content request from the sink device, skips the subsequent processing, and performs this processing. End the routine.

  Next, content output control and playable time management processing performed in SEQ1304 during streaming, which reduces the processing load on the source device, will be described with reference to FIG.

  When the source device ends or stops the transmission of the content (Yes in step S1701), the source device stops timing the timer (step S1702).

  Then, the source device checks whether or not the timer value is smaller than the content length (step S1703).

  If the timer value is smaller than the content length (Yes in step S1703), the source device adds (duration-timer value) to the playable time of the content destination sink device ( Step S1704), this processing routine is terminated.

  If the timer value is equal to or longer than the content length (No in step S1703), the source device ends the processing routine without updating the playable time of the content destination sink device. To do.

  If the processing procedures shown in FIGS. 16 and 17 are followed, it is not necessary to check the remaining playback time during content transmission. Accordingly, in the source device, the number of points where the current processing needs to be changed is reduced, and periodic processing or interruption processing during transmission becomes unnecessary, so that the processing load is reduced.

  FIG. 18 shows, in the form of a flowchart, the procedure of content output management processing executed in SEQ1302 during content movement (MOVE). Hereinafter, for the sake of convenience, description will be made assuming that, for example, the content providing unit 304 performs content output management processing in the server 201 as the source device.

The source device refers to the exchange key label K _R — label included in the content request (HTTP GET request) (step S1801), and determines whether or not the RAC record of the same exchange key label K _R — label exists in the terminal management unit 307. A check is made (step S1802).

Here, if there is no RAC record of the same exchange key label K _R _label (No in step S1802), an illegal content request may be caused by a cause such as the requesting sink device not performing the RA-AKE procedure. is there. Therefore, the Source device skips all subsequent processes and ends this processing routine. At this time, the source device may return an error response such as HTTP Status Code 406 to the sink device that is the content request source (step S1808).

On the other hand, when the RAC record of the same exchange key label K _R _label exists (Yes in step S1802), the Source device acquires the Sink-ID corresponding to the exchange key label K _R _label from the RA record ( Step S1803).

  Next, the source device acquires the reproducible time stored as a pair with the sink-ID from the remote sink registry in the terminal management unit 307 (step S1804). However, when the reproducible time of each Sink-ID is entrusted to, for example, a management server on the cloud, the source device accesses the management server via the communication / control unit 301 and sets the corresponding reproducible time. Get information.

  Further, the source device acquires the length (duration) of the content requested from the sink device (step S1805). For example, the length (duration) of the content can be acquired with reference to res @ duration in the CDS.

  Then, the source device checks whether or not the reproducible time of the sink device requesting the content is longer than the requested content length (duration) (step S1806).

  When the playable time is equal to or longer than the content duration (Yes in step S1806), the source device permits the content request from the sink device and starts transmitting the content (step S1807). The requested content is transmitted by, for example, HTTP GET response.

  When the playable time is less than the content duration (No in step S1806), the source device does not allow the content request from the sink device, skips subsequent processing, and executes this processing routine. finish. At this time, the source device may return an error response such as HTTP Status Code 406 to the sink device that is the content request source (step S1808).

  FIG. 19 is a flowchart showing the procedure of content output control and playable time management processing executed in SEQ1304 during content movement (MOVE). In the following, for the sake of convenience, description will be made assuming that, for example, the content providing unit 304 performs content output control and playable time management processing in the server 201 as the source device.

  When the movement of the content is not stopped (No in step S1901) and the movement of the content is completed successfully (step S1902), the source device determines the content of the moved content from the playable time of the content transmission destination sink device. The length (duration) is subtracted (step S1903), and this processing routine ends.

  If the content transfer is not successful (No in step 1902), the process returns to step S1901, and the source device checks again whether to stop the content transfer.

  When the movement of the content is to be stopped (Yes in step S1901), the source device ends this processing routine without subtracting the content length (duration) from the reproducible time of the content transmission destination sink device.

  The processing procedure shown in FIGS. 14 to 19 restricts the content device from providing content based on the remaining playable time of the sink device in the content transmission phase so that the use of content from a remote location cannot be made permanent. ing.

  On the other hand, in the content list browsing phase (see FIG. 8) preceding the content transmission phase, the source device restricts the content information permitted to be browsed based on the remaining playable time of the sink device. A modified example is also conceivable.

  For example, when a Sink device requests a CDS, it includes its Sink-ID in a header field (for example, DTCPID.ARIB.OR.JP) in an HTTP request. When the source device obtains the playable time of the requesting sink device based on the sink-ID, the CDS is not passed to the sink device whose playable time is zero, or content with a duration longer than the playable time is received. Restrict not to notify as available. On the sink device side, the request for the content is suppressed by restricting the browsing to the information of the content that is not provided to itself (although the source device can be provided).

  In FIG. 20, in the content list browsing phase (SEQ801), the source device restricts the provision of the CDS information to the sink device to be remotely accessed based on the playable time of the sink device. It is shown in the form of a flowchart.

  First, the source device clears content information that can be provided (step S2001). Next, the source device acquires the reproducible time corresponding to the sink-ID of the requesting sink device from the remote sink registry (step S2002).

  Here, the source device checks whether or not the reproducible time of the requesting sink device is greater than zero (step S2003). When the reproducible time is zero (No in step S2003), the source device does not permit the content information request from the sink device, skips the subsequent processing steps S2004 to S2008, and ends this processing routine.

  On the other hand, when the reproducible time of the requesting sink device is greater than zero (Yes in step S2003), content information is created until all content information is processed (No in step S2004). That is, when the source device refers to the content information of the unprocessed content (step S2005), the source device acquires the length of the content from res @ duration in the CDS (step S2006).

  Then, the source device compares the length (duration) of the content with the reproducible time of the requesting sink device (step S2007).

  When the length of the content is less than the reproducible time of the sink device (Yes in step S2007), the source device adds this content information to the content information that can be provided (step S2008). Then, the process returns to step S2004 to check whether all content information has been processed.

  On the other hand, when the length of the content exceeds the reproducible time of the sink device (No in step S2007), the process returns to step S2004, and the source device checks whether all content information has been processed. However, when the content output control and reproducible time management processing of FIG. 13 is performed by the processing of FIG. 15 during streaming, the content is moved when the content length exceeds the reproducible time of the sink device. It is also conceivable that the content information is added to the content information that can be provided. For example, in DLNA Guidelines Part4, DTCP.com in res @ protocolInfo. The set / reset of bit 31 of COM_FLAGS param indicates whether the content can be moved.

  When the processing of all the content information is completed (Yes in step S2004), the source device transmits the completed content information to the requesting sink device (step S2009).

  As described above, it is possible to prevent content from being used from a remote location permanently by providing content information to a sink device by limiting the content to a content whose duration is less than or equal to the reproducible time. it can.

D. Notification of reproducible time In this embodiment, the server 201 resets the reproducible time of the re-registered terminal 202 to an initial value so that it is convenient for the user who wants to view content during a trip or business trip. Yes.

  Further, the server 201 may notify the terminal 202 of the remaining playable time during content transmission. On the terminal 202 side, by displaying the reproducible time during the reproduction of the received content, it is possible to prevent the content from being reproduced without the user's knowledge and to prompt re-registration to the server 201. .

  For example, as shown in FIG. 21, the server 201 can store information on the reproducible time in a header field of an HTTP (Hyper Text Transfer Protocol) message when performing content transmission. In the figure, it is understood that the sink device corresponds to the terminal 202 and the source device corresponds to the server 201.

The sink device requests content transmission to the source device by an HTTP request (HTTP GET request) using the HTTP GET method (SEQ2201). At the time of the request, along with the URL (Uniform Resource Locator) of the content, and sends the label K _R _label the ID of the exchange key K _R for remote access. We define a header field for sending ID (K _R _label) of the exchange key to the Source device from Sink device.

On the other hand, the Source device specifies the Sink-ID of the requesting Sink device from the RAC Record corresponding to the exchange key label K _R _label included in the content request. When the current value of the reproducible time registered in the remote sink registry is acquired as a pair with the Sink-ID, the header value RSRREmainTime. Of the HTTP response (HTTP GET response) is obtained. ARIB. OR. It is included in the JP and transmitted to the sink device (SEQ2202). In the illustrated example, the reproducible time 1234 minutes is described.

  FIG. 22 shows a processing procedure for the sink device to display the reproducible time notified from the source device in the form of a flowchart.

  First, the sink device stores the length (duration) of the content to be reproduced in the variable D (step S2301). The length of the content can be obtained by referring to res @ duration in the CDS, for example.

  Next, the sink device stores the playable time described in the header field of the HTTP GET response in the variable R (step S2302).

  Then, the sink device compares the value of D with the value of R (step S2303). Here, when D is larger than R (Yes in step S2303), the content duration is longer than the remaining playable time of the sink device, and the content cannot be played to the end. . Therefore, the sink device displays a warning that the content to be played cannot be played to the end, for example, on the display unit (described above) of the content playback output unit 405 (step S2304).

  Next, when the sink device starts measuring the timer 2 from zero (step S2305), while the content is being received (No in step S2307), the value obtained by subtracting the value of the timer 2 from R is the current reproducible time. For example, it continues to be displayed on the display unit (described above) of the content reproduction output unit 405 (step S2306). Note that when the content output control and the reproducible time management of FIG. 13 are performed in the processes of FIGS. 16 and 17, the value of the timer 2 may be greater than R. In this case, the reproducible time is zero. Shall be displayed.

  As described above, according to the content transmission system according to the present embodiment, the content transmission device, that is, the source device, limits the playable time when the content reception device, that is, the sink device receives content by remote access, It is possible to make it impossible to use content from a remote location. Further, by notifying the remaining playable time in the content receiving device, it is possible to prevent the content from being unable to be played back without the user's knowledge.

E. Specific examples of content transmission devices Specific examples of content transmission devices that operate as server 201 or DTCP source devices include NAS (Network Attached) such as set-top boxes, recorders, television receivers, personal computers, and network hard disks. Storage).

  FIG. 23 illustrates a configuration example of a personal computer 2400 that can operate as the server 201 or a DTCP Source device. The personal computer 2400 remote access function (described above) is also supported. The illustrated personal computer 2400 includes a CPU (Central Processing Unit) 2401, a RAM (Random Access Memory) 2402, an EEPROM (Electrically Erasable and Programmable ROM) 2403, a display 2404, a speaker 2405, for example, an HDD (hard DRD). The circuit component includes a large-capacity information storage device 2406 such as a Super Density Disc) and an I / O interface 2407, and these circuit components are interconnected via a bus 2408.

  The CPU 2401 reads and executes a program loaded on the RAM 2402 as the main memory.

  The RAM 2402 is loaded with functions related to content encryption and decryption. For example, a program for executing the DTCP + function and a program for executing the RA-AKE process are loaded into the RAM 2402. A program for executing an authentication sequence (see FIG. 6) when registering a sink device's Sink-ID as a pair with a reproducible time is one of programs for executing RA-AKE processing. As a unit, it is loaded into the RAM 2402 and executed by the CPU 2401.

  The EEPROM 2403 is a rewritable nonvolatile storage device that stores setting information and the like. When the personal computer 2400 operates as a source device, that is, a content transmission apparatus, the sink-ID of the sink device is stored in the EEPROM 2403 as a pair with the reproducible time.

  On the personal computer 2400, when receiving a request from the sink device to register as a terminal capable of remote access, the CPU 2401 reads out a program describing the DTCP-IP AKE process from the RAM 2402, and communicates with the sink device. AKE procedure is executed between.

  If this procedure is successful, the CPU 2401 assigns a reproducible time (initial value) to the sink device according to the program stored in the RAM 2402, and stores it in the EEPROM 2403 as a pair with the sink-ID.

  Thereafter, on the personal computer 2400, when the CPU 2401 receives a request for RA-AKE processing, it compares the sink-ID of the sink device making the request with the sink-ID stored in the EEPROM 83, A process for determining whether or not to complete the RA-AKE process is executed.

  When the RA-AKE process is completed, a common content key is generated between the personal computer 2400 and the sink device that has requested the RA-AKE process. On the personal computer 2400 side, the generated content key is temporarily stored, and when the content is read from the large-capacity information storage device 2406, the content is encrypted with the temporarily stored content key. The encrypted content is output to the outside via the I / O interface 2408. When the I / O interface 2408 has a wireless LAN function, the encrypted content is transmitted to the sink device that has requested the RA-AKE process via the wireless LAN.

  FIG. 24 shows a configuration example of a recorder 2500 that can operate as the server 201 or a DTCP Source device. It is assumed that the recorder 2500 also supports a remote access function (described above). The recorder 2500 shown includes a system chip 2501, a mass storage device 2502, a RAM 2503, an EEPROM 2504, a wireless LAN chip 2505, or a LAN port 2509, a tuner 2506, a display 2507, and a speaker 2508.

  The system chip 2501 includes circuit modules such as a CPU 2501a, a coprocessor 2501b, and an interface function unit 2501c, and these circuit modules are interconnected by a bus 2501d in the chip.

  The CPU 2501a can execute a program stored in a storage device connected via the interface function unit 2501c.

  The coprocessor 2501b is an auxiliary arithmetic device, and mainly executes moving image compression or decoding processing. For example, an algorithm such as H264, VC1, MPEG2, or JPEG is executed. The coprocessor 2501b converts the image size according to the communication environment such as the communication speed when transmitting the moving image content (stored in the mass storage device 2502) to a content receiving device such as a sink device. Then, processing for enabling transmission at a size optimum for the communication environment, that is, transcoding of the codec is performed. Due to transcoding of the codec, it is possible to reduce a delay in reproduction at a content transmission destination such as a sink device. However, transcoding of the codec can be performed by the CPU 2501a instead of dedicated hardware such as the coprocessor 2501b. Also, the compression rate for transcoding content can be specified by the user for each content.

  The mass storage device 2502 is, for example, an HDD or an SDD, and stores content to be provided to a sink device or a content receiving device.

  The tuner 2506 selects and receives a broadcast signal such as terrestrial digital broadcast. In the present embodiment, for example, according to a function such as EPG (Electronic Program Guide), a program is recorded or reserved for recording, and broadcast content is stored in the mass storage device 2502.

  Broadcast programs received by the tuner 2506 and contents stored in the large-capacity storage device 2502 can be viewed using the displays 2507 and 2508.

  The wireless LAN chip 2505 performs processing of a physical layer and a MAC (Media Access Control) layer in a wireless LAN standard such as Wi-Fi (Wireless Fidelity) or IEEE 802.11, for example, via a predetermined access point or as a sink device. Direct wireless connection with other content receivers. The LAN port 2509 is connected to a wired LAN (not shown) such as Ethernet (registered trademark) via a plugged-in LAN cable 2509A, and for example, a physical layer and a MAC layer in a wired LAN standard such as IEEE802.3. To communicate with a content receiving apparatus as a sink device.

  A program executed by the CPU 2501a is loaded into the RAM 2503 as the main memory. The main program loaded into the RAM 2503 is a program that realizes functions related to content encryption and decryption. For example, a program for executing the DTCP + function and a program for executing the RA-AKE processing are stored in the RAM 2503. Loaded.

  The EEPROM 2504 is a rewritable nonvolatile storage device and stores setting information and the like. When the recorder 2500 operates as a source device, that is, a content transmission apparatus, the sink device's sink-ID is stored in the EEPROM 2504 as a pair with the playable time.

  On the recorder 2500, when receiving a request from the sink device to register as a terminal capable of remote access, the CPU 2501a reads a program in which DTCP-IP AKE processing is described from the RAM 2503, and receives a request from the sink device. Execute the AKE procedure.

  If this procedure is successful, the CPU 2501a gives a reproducible time (initial value) to the sink device according to the program stored in the RAM 2503, and stores it in the EEPROM 2504 as a pair with the sink-ID.

  Thereafter, on the recorder 2500, when the CPU 2501a receives a request for RA-AKE processing, the sink device's sink-ID making the request is compared with the sink device's sink ID stored in the EEPROM 2504. -A process for determining whether or not to complete the AKE process is executed.

  When the RA-AKE process is completed, a common content key is generated between the recorder 2500 and the sink device that has requested the RA-AKE process. On the recorder 2500 side, the generated content key is temporarily stored, and when the content is read from the large-capacity information storage device 2502, the content is encrypted with the temporarily stored content key. The encrypted content is transmitted through the interface function unit 2501c and the wireless LAN chip 2505 to the terminal that has requested the RA-AKE process.

  FIG. 25 shows a configuration example of a NAS (Network Attached Storage) 2600 that can operate as the server 201 or a DTCP Source device.

  A NAS (Network Attached Storage) 2600 includes a mass storage device and is installed in the home networks 110 and 210 to transmit information in the mass storage device in accordance with the IP protocol. For example, the broadcast content recorded by the recorder 2500 is dubbed to the network access server 2600, or the content stored in the NAS (Network Attached Storage) 2600 is transmitted to a sink device such as a personal computer 2400 or a smartphone for viewing. Can be. Further, it is assumed that NAS (Network Attached Storage) 2600 also supports a remote access function (described above).

  The illustrated NAS (Network Attached Storage) 2600 includes at least one of a system chip 2601, a mass storage device 2602, a RAM 2603, an EEPROM 2604, a wireless LAN chip 2605, or a LAN port 2606.

  The system chip 2601 includes circuit modules such as a CPU 2601a, a coprocessor 2601b, and an interface function unit 2601c, and these circuit modules are interconnected by a bus 2601d in the chip.

  The CPU 2601a can execute a program stored in a storage device connected via the interface function unit 2601c.

  The coprocessor 2601b is an auxiliary arithmetic device, and mainly executes moving image compression or decoding processing. For example, an algorithm such as H264, VC1, MPEG2, or JPEG is executed. The coprocessor 2601b converts the image size according to the communication environment such as the communication speed when transmitting the moving image content (stored in the mass storage device 2602) to the content receiving device such as a sink device. Then, processing for enabling transmission at a size optimum for the communication environment, that is, transcoding of the codec is performed. Due to transcoding of the codec, it is possible to reduce a delay in reproduction at a content transmission destination such as a sink device. However, transcoding of the codec can be performed by the CPU 2601a instead of the dedicated hardware such as the coprocessor 2601b. Also, the compression rate for transcoding content can be specified by the user for each content.

  The mass storage device 2602 is, for example, an HDD or an SDD, and stores content to be provided to a sink device or a content receiving device. For example, broadcast content recorded by the recorder 2500 can be dubbed to the mass storage device 2602 (received via the wireless LAN chip 2605).

  The wireless LAN chip 2605 performs processing of a physical layer and a MAC (Media Access Control) layer in a wireless LAN standard such as Wi-Fi (Wireless Fidelity) or IEEE 802.11, for example, via a predetermined access point or as a sink device. Direct wireless connection with other content receivers. The LAN port 2606 is connected to a wired LAN (not shown) such as Ethernet (registered trademark) via a plugged LAN cable 2606A, and also includes a physical layer and a MAC layer in a wired LAN standard such as IEEE 802.3, for example. To communicate with a content receiving apparatus as a sink device.

  A program executed by the CPU 2601a is loaded into the RAM 2603 as the main memory. The main program loaded into the RAM 2603 is a program that realizes functions related to content encryption and decryption. For example, a program for executing the DTCP + function and a program for executing the RA-AKE process are stored in the RAM 2603. Loaded.

  The EEPROM 2604 is a rewritable nonvolatile storage device that stores setting information and the like. When the network access server 2600 operates as a source device, that is, a content transmission apparatus, the sink-ID of the sink device is stored in the EEPROM 2604 as a pair with the playable time.

  On the network access server 2600, when receiving a request from the sink device to register as a terminal capable of remote access, the CPU 2601a reads a program describing the DTCP-IP AKE process from the RAM 2603, and the sink device AKE procedure is executed between

  If this procedure is successful, the CPU 2601a gives a reproducible time (initial value) to the sink device according to the program stored in the RAM 2603, and stores it in the EEPROM 2604 as a pair with the sink-ID.

  Thereafter, on the NAS (Network Attached Storage) 2600, when the CPU 2501a receives a RA-AKE processing request, the sink device's sink ID and the sink device's sink ID stored in the EEPROM 2604 are received. And a process for determining whether or not to complete the RA-AKE process.

  When the RA-AKE process is completed, a common content key is generated between the NAS (Network Attached Storage) 2600 and the sink device that has requested the RA-AKE process. On the NAS (Network Attached Storage) 2600 side, the generated content key is temporarily stored, and when the content is read from the large-capacity information storage device 2602, this content is encrypted with the temporarily stored content key. To do. The encrypted content is transmitted through the interface function unit 2601c and the wireless LAN chip 2605 to the terminal that has requested the RA-AKE process.

  As described above, the technology disclosed in this specification has been described in detail with reference to specific embodiments. However, it is obvious that those skilled in the art can make modifications and substitutions of the embodiments without departing from the scope of the technology disclosed in this specification.

  In the present specification, the technology disclosed in the present specification has been described mainly with respect to an embodiment in which the technology disclosed in this specification is applied to a network of DTCP and DTCP-IP specifications. However, the gist of the technology disclosed in this specification is limited to this. is not. The technology disclosed in the technology disclosed in the present specification can also be applied to various communication systems other than DTCP-IP that have restrictions on remote access to content in a home network.

  Further, the scope of application of the technology disclosed in this specification is not limited to remote access to a home network. Similarly, the technology disclosed in this specification can be applied to restrict the use of content based on the reproducible time for each terminal even during local access within the home network.

  In short, the technology disclosed in the present specification has been described in the form of exemplification, and the description content of the present specification should not be interpreted in a limited manner. In order to determine the gist of the technology disclosed in this specification, the claims should be taken into consideration.

Note that the technology disclosed in the present specification can also be configured as follows.
(1) a content acquisition unit that acquires content to be provided to the terminal, or a content recording unit that records content to be provided to the terminal;
A terminal providing a content and a terminal management unit for managing the playable time of the content in the terminal;
A content provider that controls transmission of content to the terminal based on the playable time;
A content transmission apparatus comprising:
(2) further comprising an authentication and key sharing unit for authenticating the terminal according to a predetermined mutual authentication and key exchange procedure and sharing the exchange key;
The content providing unit provides the terminal with content encrypted using the exchange key;
The content transmission device according to (1) above.
(3) The authentication and key sharing unit performs mutual authentication and exchange key sharing with a terminal according to an authentication and key exchange (AKE) algorithm defined by DTCP-IP.
The terminal registration unit registers a terminal according to a procedure specified by DTCP-IP.
The content transmission device according to (2) above.
(4) The terminal management unit registers the terminal in the home network,
The content providing unit provides content only to a terminal that has been registered in response to access from an external network.
The content transmission device according to (1) above.
(5) The terminal management unit gives an initial value of the playable time to the terminal at the time of registration.
The content transmission device according to (4) above.
(6) The terminal management unit resets the reproducible time of the terminal to be re-registered to the initial value.
The content transmission device according to (4) above.
(7) The content providing unit permits transmission of content until the reproducible time of the terminal becomes zero.
The content transmission device according to (4) above.
(8) The content providing unit subtracts the reproduction time of the transmitted content from the reproducible time of the terminal when the transmission of the content is terminated or stopped.
The content transmission device according to (7) above.
(9) The content providing unit transmits content shorter than the reproducible time to the terminal after subtracting the content length from the reproducible time of the transmission destination terminal.
The content transmission device according to (4) above.
(10) The content providing unit adds a value obtained by subtracting the playback time of the transmitted content from the length of the content to the playable time of the transmission destination terminal when the transmission of the content is terminated or stopped.
The content transmission device according to (9) above.
(11) The content providing unit permits movement of content shorter than the reproducible time to the terminal.
The content transmission device according to (4) above.
(12) The content providing unit subtracts the length of the moved content from the playable time of the destination terminal.
The content transmission device according to (11) above.
(13) The terminal management unit deletes registration of a terminal whose playable time has become zero,
The content transmission device according to (4) above.
(14) When the content providing unit provides the content, the content providing unit notifies the providing destination terminal of the current playable time.
The content transmission device according to (1) above.
(15) It further includes a content information providing unit that provides information related to content that can be provided to the terminal to the terminal,
The content providing unit provides content selected via content information viewed on the terminal side;
The content transmission device according to (1) above.
(16) The content information providing unit controls the provision of content information based on the current reproducible time of the provision destination terminal.
The content transmission device according to (15) above.
(17) The content information providing unit restricts the provision of content information of content longer than the current playable time of the terminal of the providing destination.
The content transmission device according to (15) above.
(18) The content information providing unit restricts the provision of content information to a terminal whose current playable time is zero.
The content transmission device according to (15) above.
(19) a content acquisition step of acquiring content to be provided to the terminal, or a content recording step of recording content to be provided to the terminal;
A terminal management step for managing a terminal that provides the content and a playable time of the content in the terminal;
A content providing step of controlling transmission of content to the terminal based on the playable time;
A content transmission method comprising:
(20) A content acquisition unit that acquires content to be provided to the terminal, or a content recording unit that records content to be provided to the terminal,
A terminal that provides content, and a terminal management unit that manages the content reproducible time in the terminal;
A content providing unit that controls transmission of content to the terminal based on the playable time;
A computer program written in a computer-readable format to make a computer function as

DESCRIPTION OF SYMBOLS 100 ... Content transmission system 101 ... Server, 102 ... Terminal, 110 ... Home network 201 ... Server, 202 ... Terminal 200 ... Content transmission system 201 ... Server, 202 ... Terminal 210 ... Home network, 220 ... External network 230 ... Router 300 ... Content transmission device (Source device)
DESCRIPTION OF SYMBOLS 301 ... Communication / control part 302 ... Content recording part 303 ... Content acquisition part 304 ... Content provision part 305 ... Content list provision part, 306 ... Authentication and key sharing part 307 ... Terminal management part 400 ... Content receiving apparatus 401 ... Communication / control unit 402 ... Content list browsing unit, 403 ... Content acquisition unit 404 ... Content decryption unit, 405 ... Content reproduction output unit 406 ... Authentication / key sharing unit, 407 ... Input unit 2400 ... Personal computer, 2401 ... CPU
2402 ... RAM, 2403 ... EEPROM, 2404 ... display 2405 ... speaker, 2406 ... mass storage device 2407 ... I / O interface, 2408 ... bus 2500 ... recorder, 2501 ... system chip, 2501a ... CPU,
2501b ... Coprocessor, 2501c ... Interface function unit 2501d ... Bus, 2502 ... Mass storage device, 2503 ... RAM
2504 ... EEPROM, 2505 ... Wireless LAN chip 2506 ... Tuner, 2507 ... Display, 2508 ... Speaker 2509 ... LAN port, 2509A ... LAN cable 2600 ... NAS (Network Attached Storage)
2601: System chip, 2601a: CPU,
2601b ... Coprocessor, 2601c ... Interface function unit 2601d ... Bus, 2602 ... Mass storage device, 2603 ... RAM
2604 ... EEPROM, 2605 ... Wireless LAN chip 2606 ... LAN port, 2606A ... LAN cable 2700 ... Computer program distribution system, 2710 ... Server 2711 ... Storage device, 2712 ... Communication device, 2713 ... Information notification device

Claims (19)

A content acquisition unit that acquires content to be provided to the terminal, or a content recording unit that records content to be provided to the terminal;
A terminal management unit for registering a terminal that provides content under the restriction of RTT (Round Trip Time), and managing a reproducible time of the content in the terminal to be registered;
A content providing unit that controls transmission of content to the terminal based on the reproducible time managed by the terminal management unit without imposing restrictions on the RTT for the registered terminal;
A content transmission apparatus comprising: An authentication and key sharing unit for authenticating the terminal according to a predetermined mutual authentication and key exchange procedure and sharing the exchange key;
The content providing unit provides the terminal with content encrypted using the exchange key;
The content transmission apparatus according to claim 1. The authentication and key sharing unit performs mutual authentication and exchange key sharing with a terminal according to an authentication and key exchange (AKE) algorithm defined by DTCP-IP.
The terminal management unit registers a terminal according to a procedure defined by DTCP-IP.
The content transmission apparatus according to claim 2. The terminal management unit gives an initial value of playable time to the terminal at the time of registration,
The content transmission device according to claim 3. The terminal management unit resets the reproducible time of the terminal to be re-registered to an initial value ;
The content transmission device according to claim 3. The content providing unit permits transmission of content until the reproducible time of the terminal becomes zero.
The content transmission device according to claim 3. The content providing unit subtracts the reproduction time of the transmitted content from the reproducible time of the terminal when transmission of the content is terminated or stopped,
The content transmission apparatus according to claim 6. The content providing unit transmits content shorter than the reproducible time to the terminal after subtracting the length of the content from the reproducible time of the transmission destination terminal.
The content transmission device according to claim 3. When the content providing unit ends or stops the transmission of the content, the value obtained by subtracting the playback time of the transmitted content from the length of the content is added to the playable time of the transmission destination terminal.
The content transmission apparatus according to claim 8. The content providing unit permits movement of the content shorter than the reproducible time to the terminal;
The content transmission device according to claim 3. The content providing unit subtracts the length of the moved content from the playable time of the destination terminal.
The content transmission device according to claim 3. The terminal management unit deletes registration of a terminal whose playable time has become zero,
The content transmission device according to claim 3. When the content providing unit provides the content, the content providing unit notifies the providing destination terminal of the current playable time.
The content transmission apparatus according to claim 1. A content information providing unit that provides the terminal with information related to content that can be provided to the terminal;
The content providing unit provides content selected via content information viewed on the terminal side;
The content transmission apparatus according to claim 1. The content information providing unit controls the provision of content information based on the current reproducible time of the provision destination terminal.
The content transmission apparatus according to claim 14. The content information providing unit restricts the provision of content information of content longer than the current playable time of the terminal of the providing destination;
The content transmission apparatus according to claim 14. The content information providing unit restricts the provision of content information to a terminal whose current playable time is zero;
The content transmission apparatus according to claim 14. A content acquisition step of acquiring content to be provided to the terminal, or a content recording step of recording content to be provided to the terminal;
A terminal management step of registering a terminal that provides content under the restriction of RTT (Round Trip Time), and managing a reproducible time of the content in the terminal to be registered;
A content providing step for controlling transmission of content to the terminal based on the reproducible time managed in the terminal management step without imposing an RTT restriction on the registered terminal;
A content transmission method comprising: A content acquisition unit for acquiring content to be provided to the terminal, or a content recording unit for recording content to be provided to the terminal,
A terminal management unit for registering a terminal that provides content under the restriction of RTT (Round Trip Time) and managing the playable time of the content in the terminal to be registered;
A content providing unit that controls transmission of content to the terminal based on the reproducible time managed by the terminal management unit without imposing an RTT restriction on the registered terminal;
A computer program written in a computer-readable format to make a computer function as