JP2004303108A - Terminal equipment with license moving function - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide terminal equipment which moves encrypted contents and license to the terminals or media of a different copyright protection system. <P>SOLUTION: This terminal equipment connected through a communication network to a license server is provided with a license managing means for acquiring a license for using encrypted contents from the license server, a means for acquiring a license from a license sever, a means for returning the license whose use is ended to the license server, a means for converting the license for a different copyright protecting system, and for inserting information to be returned into contents by using electronic watermarks, and a means for making the means for returning the license to the license server detect the electronic watermarks inserted into the contents to detect the information to be returned, and return the license. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a technology for protecting the copyright of content by using encryption and a digital watermark, and more particularly to an apparatus and a system for suppressing unauthorized copying of a content using terminal.
[0002]
[Prior art]
Services for distributing content such as movies and music by communication means such as the Internet and satellite broadcasting have been proposed. Since data handled by such a system is digitized and can be easily copied, it is important to protect the copyright of the content. As one of means for that, a method of encrypting and distributing content has been proposed. In this method, the content is encrypted by, for example, a public key cryptosystem, and at the same time, a decryption key for decrypting the encrypted content is created. Since encrypted content cannot be reproduced without the corresponding decryption key, managing the license in which the decryption key and its use condition are paired prevents illegal use of the content and protects the rights of the content creators. In such a system, licenses are generally charged.
[0003]
For example, in the delivery of content using a communication network such as the Internet, the content is encrypted with a content key, and the usage conditions are encapsulated and delivered as a ticket (corresponding to the license). There is a license management method that allows a ticket to be moved to another terminal when the use of the ticket is permitted as a usage condition, and the ticket is returned to the server when the use of the content at the terminal is completed (Move -In / Move-out) (see Patent Document 1).
[0004]
In the content distribution service based on the copyright protection technology as described above, the license of the distributed content must be securely managed by the terminal.
[0005]
[Patent Document 1]
JP-A-2002-342518 (page 16, FIG. 15)
[0006]
[Problems to be solved by the invention]
In the above conventional technique, the copyright is protected by using encrypted content data, a decryption key (content key) for decrypting the data, and a use condition (hereinafter, referred to as a license) thereof. In the content distribution service, the content use terminal decrypts (decrypts) the encrypted content using the content key included in the license. Thereafter, the decrypted content is decoded (decompressed) as necessary and output to a TV or a content display means provided in the terminal. Return the license to the server when the use of the content ends. By doing so, it is designed so that another terminal can obtain a license and use the content.
[0007]
However, when transferring encrypted content and a license to a terminal or media of a different copyright protection system, it may not be possible to specify the return destination server when the content is used and returned to the server. .
[0008]
SUMMARY OF THE INVENTION An object of the present invention is to, in license management for transferring a license to a different copyright protection system, when moving a license to another terminal, insert information for specifying a server that returns the license into a content as a digital watermark. Accordingly, an object of the present invention is to provide a terminal device with a license transfer function capable of acquiring information on a return destination server even in a copyright protection system having no means for storing information for returning a license.
[0009]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the present invention provides a terminal device, comprising: a terminal device that transmits data to a license server that issues a license purchased by a user via a public network such as an optical line, a CATV network, and a telephone line or a dedicated communication network; Communication means for transmitting and receiving the license, and securely storing the license obtained from the license server against physical and electrical attacks, and communicating with other than a legitimate device authorized to use the license. A license management unit having a function of authenticating a communication partner and a function of encrypting communication with the partner so as not to perform the operation, a unit for obtaining a license from the license server, and The means for returning to the server and the information for converting the license to a different copyright protection system and returning it are digitally watermarked. Means for inserting the content had was configured to have a means for performing a return by detecting the information when returning to detect in advance the content inserted watermark in the means for returning the license to the license server. As a result, it is possible to transfer licenses to a copyright protection system that has no means for storing information on the server at the return destination, and it is expected that the content will be available on more terminals and user usability will be improved. it can.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described with reference to the drawings.
[0011]
FIG. 1 is a diagram illustrating an example of a system configuration of a content distribution system (copyright management system) to which the terminal device with a license transfer function according to the embodiment can be applied.
[0012]
In FIG. 1, reference numeral 10 denotes a terminal device, reference numeral 20 denotes a license server, reference numeral 30 denotes a wired or wireless public communication network or dedicated communication network, and reference numeral 9 denotes a terminal device of a different copyright protection system.
[0013]
The terminal device 10 has a function of decrypting and playing back the encrypted content transmitted from the content distribution server 32 using the content key included in the license transmitted from the license server 31, and a license for a terminal of a different copyright protection system. And the function of inserting and moving the information of the return destination server as a digital watermark.
[0014]
The communication network 20 is a network including an optical network, a CATV network, a telephone network, and the like, and enables data to be exchanged between devices connected to the communication network 20 according to a predetermined procedure. .
[0015]
The license server 31 has a function of managing a license for content that is encrypted and distributed to the terminal device 10 and transmitting the license in response to a request from the terminal device 10.
[0016]
The content distribution server 32 has a function of distributing the encrypted content to the terminal device 10, and the license server 31 manages the content key of the content distributed from the content distribution server 32.
[0017]
The portal server 33 is configured as a so-called Web server, and has a function for the user to purchase (a license for) the content, and for the terminal device 10 to display a list of the user purchased content.
[0018]
A service center system 30 is composed of at least the license server 31, the content distribution server 32, and the portal server 33. The license server 31, the content distribution server 32, and the portal server 33 are connected to the communication network 20 via a router or the like (not shown). Normally, the service center system 30 is installed for each business entity that provides a content distribution service, and a plurality of service center systems 30 may be connected to the communication network 20 (not shown).
[0019]
In the content distribution system of the present embodiment, the content is encrypted and distributed from the content distribution server 32. The user accesses the portal server 33 from the terminal device 10 in advance and purchases a license for the content to be used (viewed). The purchased license is held in the license server 31 for each purchased user. When the terminal device 10 uses the content corresponding to the license purchased by the user, if the terminal device 10 does not store the license, the terminal device 10 obtains the license from the license server 31 and decrypts the decryption key (content The key is used to decrypt and reproduce the content. As a result, the user can use the content.
[0020]
FIG. 2 is a hardware configuration diagram of the terminal device 10 to which the present embodiment can be applied.
[0021]
As shown in FIG. 2, the terminal device 10 includes a CPU 11, a main memory 12, a communication control device 13, a storage device 14, a license management device 15, a content reproduction device 16, a license transfer device 8, It comprises a device 17 and an input device 18. The components of the terminal device 10 are connected by a bus 19 so that necessary information can be transmitted between the components.
[0022]
The CPU 11 performs a predetermined operation according to a program stored in the main memory 12 or the storage device 14 in advance.
[0023]
The main memory 12 functions as a work area and stores necessary programs. For example, the main memory 12 can be realized by a RAM for the former and a ROM for the latter.
[0024]
The communication control device 13 is means for transmitting and receiving information (data) to and from a device also connected to the communication network 20 via the communication network 20, and is realized by, for example, a modem, a network adapter, a wireless transmission / reception device, and the like. You.
[0025]
The storage device 14 is a means for storing a program for controlling the operation of the terminal device 10 and for storing content distributed via the communication network 20, and is, for example, a hard disk (HDD), an optical disk, or the like. realizable.
[0026]
The license management device 15 securely stores the license against physical and electrical attacks, and authenticates the communication partner so as not to communicate with any other than a legitimate device that is authorized to use the license. Means for encrypting and transmitting data such as licenses. To strengthen security, provide resistance to external attacks.
[0027]
The content reproduction device 16 obtains a license including a content key for decrypting the encrypted content from the license management device 15, and uses the content key to encrypt the content stored in the content distribution server 32 or the storage device 14. The decrypted content is decoded, and if the decrypted content is compressed, decoded (decompressed) and transmitted to the display device 17.
[0028]
The display device 17 is a means for displaying content decoded by the content reproduction device 16 and information for responding to user operations, and is realized by a cathode ray tube, a CRT, a liquid crystal display, a PDP, a projector, speakers, headphones, and the like. it can. The display device 17 may be realized by a device different from the terminal device 10 such as a TV. In this case, the terminal device 10 includes a separate TV signal generation device such as a D / A converter, and is connected to the display device. The device 17 is connected by an AV cable, a coaxial cable, or the like.
[0029]
The license transfer device 8 acquires the license permitted to be transferred from the license management device 15 and converts the license into a license of the copyright protection system adopted by the transfer destination terminal, or receives the license from the transfer destination terminal. And converts it into a license for the copyright protection system. Also, a URL (Uniform Resource Locator) indicating the location of the license server that issued the license is inserted into the content as a digital watermark, or the digital watermark inserted from the content is detected to obtain the URL of the license server at the return destination. I do.
[0030]
The input device 18 is a means for a user to input necessary commands and information to the terminal device 10, and is realized by, for example, a remote controller used in a TV receiver, a keyboard, a mouse, and the like used in a PC. it can.
[0031]
If there is a device that is not directly related to the input and output of data and programs among the components of the terminal device 10, the device can be removed from the configuration of FIG.
[0032]
The license management device 15 can be realized by software or hardware. When the license management device 15 is realized by software, a software program that performs a function realized by the license management device 15 is stored in the main storage 12 or the storage device 14 and executed by the CPU 11. The license is encrypted using, for example, a unique ID (device ID) assigned to the license management device 15 in advance and stored in the storage device 14.
[0033]
When the license management device 15 is realized by hardware, it can be realized, for example, as one LSI or an aggregate of a plurality of LSIs. FIG. 3 shows a configuration example of the LSI.
[0034]
In FIG. 3, a CPU 71 controls each unit in the license management device 15 as a whole. Further, the CPU 71 has an authentication function and an encryption / decryption function by a program stored in the memory 72. The memory 72 includes a ROM and a RAM. The ROM stores a program for the CPU 71 to control each unit of the license management device 15 as a whole, and a program for realizing an authentication function and an encryption / decryption function. The RAM functions as a work area for the CPU 71. The nonvolatile memory 73 stores a license. The I / O circuit 74 is an interface through which each unit in the license management device 15 performs data communication with an external device via the bus 19.
[0035]
The license management device 15 can also be realized by an IC card or a memory card on which the LSI shown in FIG.
[0036]
Further, the content reproduction device 16 can be realized by software or hardware. When the content reproduction device 16 is realized by software, a software program that performs a function realized by the content reproduction device 16 is stored in the main storage 12 or the storage device 14 and executed by the CPU 11.
[0037]
The license transfer device 8 is realized by software or hardware. When realized by the license transfer device 8 or software, a software program that performs a function realized by the license transfer device is stored in the main storage 12 or the storage device 14 and executed by the CPU 11.
[0038]
When the license transfer device 8 is realized by hardware, for example, it can be realized as one LSI or an aggregate of a plurality of LSIs. FIG. 4 shows a configuration example of the LSI.
[0039]
In FIG. 4, a CPU 81 controls each unit in the license transfer device 8 as a whole. The CPU 81 has an authentication function and an encryption / decryption function by a program stored in the memory 82. The memory 82 includes a ROM and a RAM. The ROM stores a program for the CPU 81 to control each unit of the content reproduction device 16 in a centralized manner, and a program for realizing an authentication function and an encryption / decryption function. The RAM functions as a work area for the CPU 81. The nonvolatile memory 83 stores a content key. The I / O circuit 84 is an interface through which each unit in the license transfer device 8 performs data communication with an external device via the bus 19. The encryption / decryption unit 85 decrypts or encrypts the encrypted content received via the I / O circuit 84 using the content key included in the license stored in the nonvolatile memory 83. It is. The compression / expansion unit 86 is means for decoding the content decoded by the decoding unit 85 if the content is compressed, or compressing the content with the content. The watermark insertion unit 87 inserts information such as a URL indicating the position of the license server to which the license is returned (issued) stored in the non-volatile memory 83 into the content decoded by the compression / decompression unit 86 as an electronic watermark. It is a means for doing. The watermark detection unit 88 detects the digital watermark data from the content received from the destination terminal and decoded by the compression / decompression unit 86, and includes a URL indicating the position of the license server to which the license is to be returned (issued). Get information. The license conversion unit 89 converts the format of the copyright protection license adopted by the terminal of the moving destination, or converts the copyright protection license adopted by the terminal into the present copyright protection system. Means.
[0040]
The license server 31 shown in FIG. 1 can be constructed by a general PC. FIG. 5 shows a functional block diagram of the license server 31.
[0041]
As shown in FIG. 5, the license server 31 includes a communication control unit 201, an authentication unit 202, and a license issuing unit 203 as software modules executed by a CPU included in the license server 31. Further, the license server 31 holds the authentication information 205 and the license information 206 in a storage device such as a hard disk.
[0042]
The communication control unit 201 has a function of generating and interpreting a communication protocol and a message so that the authentication unit 202 and the license issuing unit 203 can communicate with another device (such as the terminal device 10 or the portal server 33).
[0043]
The authentication unit 202 has a function of performing user authentication or device authentication using the authentication information 205 in communication with the playback device 10. By associating the user ID with the device ID, the user ID can be derived from the device ID by device authentication.
[0044]
The license issuing unit 203 matches the request from the playback device 10 in the license information 206 in the communication with the playback device 10 and is included in the license purchased by the user authenticated by the authentication unit 202 or the license. It has a function of transmitting usage conditions to the playback device 10.
[0045]
The authentication information 205 stores, for each user, a user ID, user information such as a name and an address, a device ID associated with the user ID, and the like.
[0046]
The license information 206 stores the license purchased by each user.
[0047]
Next, the operation in the present embodiment will be described with reference to the drawings.
[0048]
First, the license will be described. FIG. 6 is a diagram illustrating an example of a license structure.
[0049]
The license 100 shown in FIG. 6 includes a content ID 101 holding information (content ID of the content) indicating which content the license corresponds to, and an encrypted content designated by the content ID held by the content ID 101. A content key 102 holding a decryption key, a user ID 103 for specifying a user who has purchased the license, a playback terminal ID 104 for specifying a playback terminal that can use the license, and a content ID held by the content ID 101 And a use condition 105 that holds the use condition of the encrypted content specified by the above. Further, the use condition 105 includes an area 106 for holding a viewing expiration time indicating the time limit for viewing the content, an area 107 for holding the number of viewing times indicating the number of times the content can be viewed, and an area 107 for holding the license. It is composed of an area holding a movement permission flag indicating whether movement to the terminal is permitted.
[0050]
The license 100 may be configured to include one of the user ID 103 and the playback terminal ID 104, or may be configured to include both.
[0051]
Note that, as the license usage conditions shown in FIG. 6, the viewing expiration date and the number of times of viewing have been exemplified, but the present invention is not limited thereto. For example, the viewing expiration date may be divided into the viewing start date and time and the viewing end date and time, or the total viewing time. Further, there may be no use condition for the number of times of viewing, or there may be no use condition for the viewing period and the maximum number of simultaneous issuances.
[0052]
The license 100 existing on the license management device 15 is stored in the non-volatile memory 73 or is encrypted and stored in the storage device 14, and is managed so that it cannot be accessed from outside.
[0053]
Next, a description will be given of a process performed when the user moves the purchased content (license).
[0054]
FIG. 7 is a flowchart illustrating a procedure in the terminal device 10 when the user moves the purchased content.
[0055]
First, the user selects a license desired to be moved (step S701). At this time, in order for the user to select a license to be moved, the terminal device 10 displays a list of licenses held in the portal server 33 on the display device 17. Each license held by the portal server 33 is attached with a content ID for identifying the content and information (metadata) indicating the title and content of the content, and the terminal device 10 displays the metadata of each content on the display device. By displaying the content on the display 17, the user can use the input device 18 to select and instruct the content to be moved. The metadata also includes a URL (Uniform Resource Locator) of a license server that manages a license for the content. FIG. 8 shows a screen display example displayed on the display device 17 at this time.
[0056]
In FIG. 8, for each content, a content title 301, a content (a bite digest or the like) 302, a use condition 303 included in a license for the content, information 304 as to whether or not the user has purchased the content (a license for), a license Are displayed, the permission flag 307 for moving to a terminal of a different copyright protection system is displayed. As the title 301 and the content 302, information included in the metadata of the content is displayed. At this time, if the transfer permission flag 307 for moving to a terminal of a different copyright protection system is “impossible”, the license does not move even if it is selected, so that it is not necessary to display it. The usage conditions 303 and the purchase information 304 are displayed based on the result of the communication between the terminal device 10 and the license server 31. The user selects the content to be moved using the input device 18 on the displayed result (for example, the information of the selected content is displayed in reverse video), and instructs the move button 305 to move the content. To start. When the cancel button 306 is instructed, the content (license) is not moved and returns to the initial state.
[0057]
Next, the selected license is acquired by the terminal device (S702). At this time, the license management device 15 first checks whether or not the license selected as a target to be moved exists, and if not, connects to the license server 31 and performs authentication using the authentication data from the terminal device 10. Next, the content ID included in the license to be moved is transmitted, and among all the licenses held in the license information 206, the license purchased by the user ID obtained from the authentication is searched, and the corresponding license is searched. Find a license. If they match, the license is transmitted from the license issue 203 to the terminal device 10 and stored in the license management device 15.
[0058]
Next, the license to be transferred is transmitted to the license transfer device 8 to check whether the transfer is permitted (S703). At this time, the license in the license management device 15 is made unusable, so that it cannot be used by another module, for example, the content reproduction device 16. Then, the transfer permission flag 108 for the terminal of a different copyright protection system included in the usage conditions of the license 100 is checked. At this time, if the transfer permission flag indicates "impossible", the process is stopped because the transfer is not possible, and the license in the license management device 15 is returned to a usable state and the process is terminated. If it indicates "permitted", the process proceeds to the next process.
[0059]
Next, a digital watermark is inserted into the moving content (S704). The process of inserting a digital watermark will be described with reference to FIG. First, the encrypted content and metadata are read from the storage device 14. If it is not in the storage device 14, it is acquired in advance from the content server 32. The read encrypted content is decrypted by the encryption / decryption unit 87 using the content key 102 included in the license 100. If the decrypted content is compressed, the content compressed by the compression / decompression unit 86 is further added. To be able to insert a digital watermark. Here, since the processing is also performed when reproducing the content, the processing may be performed by the content reproducing apparatus 16. However, since the data of the decrypted content flows through the bus 19, when the data of the content is transmitted to the bus 19, It is desirable to encrypt the content. Next, an electronic watermark is inserted into the content by the watermark insertion unit 87. As the data to be inserted, the URL of the license server included in the metadata is inserted. Also, data of the user who owns the license, such as the user ID 103 and the terminal ID 104 included in the license 100, may be inserted. When the digital watermark has been inserted, the compression / decompression unit 86 performs recompression processing again, and the encryption / decryption unit 87 performs reencryption processing. Here, the algorithm of recompression and re-encryption may be changed to an algorithm supported by the terminal of the moving destination. However, it is necessary for the re-encryption algorithm not to reduce the encryption strength.
[0060]
Next, license conversion is performed (S705). In this process, the license conversion unit 89 converts the license format (format). When the algorithm is changed or the key is changed in the above-described re-encryption of the content, the changed key is used. Further, it is necessary to convert the use condition within a range not exceeding the use condition of the original license.
[0061]
When these processes are completed, the converted license and the content into which the digital watermark is inserted are transmitted to terminals of different copyright protection systems (S706). At this time, since the content is encrypted, the content may be transmitted as it is. However, the license must be authenticated for use in a different copyright protection system, and the license must be encrypted and transmitted. Although transmission to the terminal has been described here, a medium such as a memory card or a magneto-optical disk having an area for storing a license (an area inaccessible to a user) may be used.
[0062]
Next, the license is deleted (S707). At this time, the license server 206 notifies the license server that the license has been transferred and stores the information for specifying the license of the transfer destination in the license information 206. Remove. By performing such processing, the movement of the content in which the license and the digital watermark are inserted is completed.
[0063]
Also, here, an example in which the digital watermark is inserted by the terminal device has been described, but the URL of the license server may be embedded in the content distributed by the content distribution server in advance. By playing, it is not necessary to insert a digital watermark in the terminal device, so that the time required for moving can be reduced.
[0064]
Next, processing for returning content (license) transferred to a terminal with different copyright protection to the server will be described.
[0065]
FIG. 9 is a flowchart showing a procedure in the terminal device 10 of returning the content (license) moved to the terminal having a different copyright protection to the server.
[0066]
First, a return license is selected (S901). Here, it connects to a terminal of a different copyright protection system and selects a license from a list of licenses (contents).
[0067]
Next, the selected license and content are received (S902). Since the content is encrypted, it may be received as it is. The received content is stored in the storage device 14, and the license at the time of transfer is deleted or made unusable. The license needs to be authenticated for use in different copyright protection systems, and the license encrypted and transmitted. In addition, data for specifying a license required when returning the license is also acquired. The license is temporarily stored in the license management device 15.
[0068]
Next, data inserted by a digital watermark is detected from the received content (S903). The procedure for detecting a watermark will be described with reference to FIG. The received content is read into the license transfer device 8, and the license is read from the license management device 15 in the same manner. At this time, since the license is read via the bus 19, it is safer to encrypt and read the license. And it is included in the license. Then, the content encrypted by the encryption / decryption unit 87 is decrypted by using the content key included in the license, and if the content is further compressed, the content compressed by the compression / decompression unit 86 is expanded to obtain a digital watermark. To be detected. Then, the watermark detection unit 88 detects the data inserted by the digital watermark.
[0069]
Next, the detected data is checked to determine whether the content has been moved (S904). If the data detected from the digital watermark is a URL indicating the location of the license server, the process proceeds to the next process because the content is a moved content. If no digital watermark data is detected or the detected data does not include the URL of the license server, the process is terminated because the content is not a moved content. At this time, the license stored in the license management device 15 is deleted so that the license of the source terminal can be used.
[0070]
Next, license conversion is performed (S905). In this process, the license conversion unit 89 converts the license format (format).
[0071]
Next, the license is returned (S906). In this process, a connection is made to the URL indicating the location of the license server detected in S903, and the license server is returned. At this time, data identifying the license acquired when the license is moved from a terminal of a different copyright system is also transmitted together to check that the license has been moved to a terminal of a different copyright system. If a user ID or a terminal ID is inserted in the electronic watermark other than the URL of the license server 31, the data may be transmitted to the license server 31 for checking.
[0072]
Next, the content is deleted (S907). When the license is returned, the content is deleted and the process is terminated.
[0073]
As described above, since the URL of the return destination is embedded as an electronic watermark in the content itself, even if there is no area for storing the URL of the license server of the return destination in a terminal of a different copyright protection system, the return can be performed. it can. In addition, since information for specifying a license in a terminal of a different copyright protection system is stored in the license server, it can be conveniently returned from a terminal device other than the terminal device that has moved.
[0074]
【The invention's effect】
As described above, according to the present invention, when a terminal device moves a license (content) to a terminal of a different copyright protection system, the URL of the license server that returns the license is inserted as a digital watermark. Even if a terminal of a different copyright protection system does not have an area for storing the URL of a license server of a return destination, the license can be returned, and a terminal device that can be returned from a terminal device other than the moved terminal is provided. be able to. As a result, improvement in the usability of the user can be expected.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a configuration example of a content distribution system according to an embodiment;
FIG. 2 is a hardware configuration diagram of the terminal device of the embodiment.
FIG. 3 is a hardware configuration diagram of the license management device of the embodiment.
FIG. 4 is a hardware configuration diagram of the license transfer device according to the embodiment;
FIG. 5 is a functional block diagram of a license server according to the embodiment.
FIG. 6 is a diagram illustrating an example of a license structure according to the embodiment;
FIG. 7 is a flowchart illustrating a procedure for moving a copyright protection system to a terminal according to a different embodiment of the present invention.
FIG. 8 is a diagram illustrating an example of a transfer license selection screen according to the present embodiment.
FIG. 9 is a flowchart showing a procedure of returning a copyright protection system from a terminal according to a different embodiment.
[Explanation of symbols]
8 License moving device, 9 Other copyright protection system terminal device, 10 Terminal device, 11 CPU, 12 Main memory, 13 Communication control device, 14 Storage device, 15 License management device, 16 Content Playback device, 17 display device, 18 input device, 19 bus, 20 communication network, 30 service center system, 31 license server, 32 content distribution server, 33 portal server, 71 CPU, 72 Memory 73, nonvolatile memory 74, I / O circuit, 81 CPU, 82 memory, 83 nonvolatile memory, 84 I / O circuit 85 encryption / decryption unit 86 compression / expansion unit 87 Watermark insertion unit, 88: watermark detection unit, 100: license, 101: content ID, 102: content key, 103: user ID, 104: re- Terminal ID, 105 use condition, 106 viewing limit, 107 viewing count, 107 permission to move to another system, 201 communication control unit, 202 authentication unit, 203 license issuing unit, 204 API unit, 205: authentication information, 206: license information.

Claims (6)

A terminal device connected to the license server via a communication network,
A license management unit that obtains a license for using encrypted content from a license server, a unit that obtains a license from the license server, and a unit that returns a used license to the license server are different from each other. A means for inserting information into the content using a digital watermark when converting and returning a license to the copyright protection system, and a means for returning the license to the license server, detecting and returning the digital watermark inserted with the content. A terminal device with a license transfer function, comprising: means for detecting and returning information when the license is transferred. A terminal device connected to the license server via a communication network,
A license management unit that obtains a license for using encrypted content from a license server, a unit that obtains a license from the license server, and a unit that returns a used license to the license server are different from each other. Means for converting a license to a copyright protection system, and means for detecting and returning information upon detecting and returning a digital watermark inserted with content in advance in the means for returning the license to the license server. A terminal device with a content protection function. The terminal device with a content protection function according to claim 1,
A terminal device with a license transfer function, wherein the information included in the license is a user ID for specifying a user who purchased the content. The terminal device with a license transfer function according to claim 1 or 2,
A terminal device with a content protection function, wherein data inserted into the content by a digital watermark is information for specifying a position of the license server. The terminal device with a license transfer function according to claim 1,
A terminal device with a content protection function, wherein data inserted as an electronic watermark into the content has added information for specifying a position of the license server and an ID for specifying a user. The terminal device with a license transfer function according to claim 1,
A terminal device with a content protection function, wherein data inserted into the content by a digital watermark has added information for specifying a position of the license server and an ID for specifying a terminal.

Images