JP2010251836A - Node device and computer program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a node which is unauthrizedly utilizing content from acquiring content by detecting the node in a P2P network for distributingly managing the content. <P>SOLUTION: Upon receiving content search request information for searching the localization of content, a node device 1 configuring the P2P network updates relay history information in which the node ID of the node device 1 as a transmission source of the content search request information is associated with a reception time. The node device 1 obtains the number of relay processings for the node device of the transmission source on the basis of the relay history information, and if the obtained number of relay processings exceeds a threshold value suspected to be unauthorization, the node ID of the node device of transmission source is output. When receiving a notice that it is not unauthorized from the node management device 8 in response to the output, the node device 1 relays the content search request information, and upon receiving a notice that it is unauthorized, the node device 1 stops the relay of the content search request information. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a node apparatus and a computer program that distribute and manage content in each node constituting a peer-to-peer (P2P) network.

<Distributed Content Management Using P2P and DHT (Distributed Hash Table)>
In recent years, the spread of the Internet is rapidly progressing in Japan, and the Internet population penetration rate reached 69.0% at the end of 2007. Among them, the number of users of broadband lines such as FTTH (Fiber to the home) and xDSL (Digital Subscriber Line) accounted for 66.1% of the Internet users, and communication using broadband Internet is natural. It is becoming. In such a broadband environment, large-capacity content such as HD (High Definition) video can be distributed. Until now, content distribution services such as video were mainly services for personal computers. In November 2007, the launch of paid video distribution services for compatible receivers by Actvila, June 2008 As represented by the establishment of the IPTV Forum, content distribution services (IPTV (Internet Protocol TeleVision) service) using communication for digital broadcast receivers are also becoming popular.

  In such content distribution services, client-server type system construction is common, but when a large-scale service and the number of users are assumed, such as content distribution companies, Problems such as increased network load occur. However, in order to solve such a problem, enormous costs are required for large-scale system construction and network infrastructure maintenance. For example, as of November 2008, the cumulative shipment number of receivers compatible with terrestrial digital broadcasting is about 44 million units, and it is necessary to solve the cost problem when the spread scale of receivers is assumed.

  As a solution to these problems, a content distribution technique using a P2P network has attracted attention. This P2P technology reduces the amount of information traffic from the server as much as possible and exchanges content between terminals, so it not only reduces the scale of system and network infrastructure construction, but also reduces server load and network load caused by congestion. It has the feature that it can be greatly reduced.

  In order to construct such a content delivery service system using the P2P technology, a function for searching and finding the location of the content in the P2P network is indispensable. There is generally known a technique that enables search and discovery of content by performing distributed management with a plurality of nodes. As one of elemental technologies for realizing such a technique, DHT (Distributed Hash Table) is known, and various algorithms such as Chord and Kademlia have been developed.

  In the distributed management of content using DHT, the content and the node exist on the same hash space. Each node uses content information (hereinafter referred to as a “content management list”) that exists in the vicinity of the hash space among the information on the location of the content that exists in the entire system (the node that holds the content). Maintain and manage. In addition, each node holds and manages transfer destination information (hereinafter referred to as a “node list”) such as an IP address and a port of a node existing in the vicinity in the hash space. In a network in which content distribution management is performed, when a node searches for the location of desired content, a search message is transmitted to other nodes using a node list. To the management node that manages the desired content. Then, the content management node notifies the search source node of which node the content to be searched is stored, that is, the location of the content. Each node holds and manages information (hereinafter referred to as a “download list”) for managing content stored in the node.

  Chord which is a typical DHT algorithm arranges nodes and contents in an annular shape in the order of hash values, and defines a length measured clockwise as a distance in the hash space. Kademlia arranges nodes and contents on a structure such as a binary tree based on a hash value, and defines a Hamming distance of the hash value as a distance in the hash space. By using this distance information, contents and nodes can be searched by each node.

<Unauthorized distribution of content and countermeasures>
With the spread of the Internet, digital content has been widely distributed, but technology that protects copyrighted content such as movies, TV programs, music, and software is essential. In a copyrighted content distribution service, DRM (Digital Rights Management) is generally used to protect content by setting content usage restrictions such as the number of usages and usage period.

  P2P type systems are roughly classified into two types, one is a management type P2P in which users and distribution contents are managed by an administrator such as a content distribution company, and the other is that there is no administrator. In other words, it is an unmanaged P2P that allows an unspecified number of users to distribute an unspecified number of contents. And when a distribution company distributes a copyrighted content normally using a management type P2P system, it is common to protect and distribute the content with DRM. On the other hand, in the unmanaged P2P, copyright infringement due to illegal distribution of copyrighted content is a problem.

  Patent Document 1 discloses a technique for realizing content distribution control by an operator by setting content permitted to be distributed by the operator in a relay server in advance and verifying the content passing through the relay server. . Further, in Non-Patent Document 1, in order to protect copyrighted content in a managed P2P system, a terminal that is authorized by an operator by performing autonomous authentication between terminals at the time of content acquisition We are investigating a method to allow distribution of content only for those. In this way, there is a restriction that even content protected by DRM can be used only by a terminal managed by the operator.

JP 2006-323644 A

Kiyohiko Ishikawa, Arisa Fujii, Toshiyuki Ohtsuki, “Distribution Control Method for Digital Content in P2P Network Using DHT”, IEICE, 2008 Symposium on Cryptography and Information Security (SCIS2008), Heisei January 22, 20

  In a content distribution service that distributes copyrighted content, it is common to distribute content protected by DRM, and a user cannot use the content without obtaining a license from the operator. However, if the encryption method used in DRM is illegally decrypted, the content can be used without a license, and it becomes difficult for the operator to control the distribution of the content. In other words, the content flows out of the range in which the business operator can control the distribution according to the procedure of granting the license, and it is difficult for the business operator to ensure copyright protection. For this reason, in addition to a mechanism capable of controlling the distribution of the content provided by the business operator, a mechanism for preventing the content from illegally flowing out of the distribution control range is required.

  On the other hand, Patent Document 1 and Non-Patent Document 1 show a method in which an operator can control the distribution of content on a P2P network. However, an unauthorized node appears that obtains the content provided by the operator by illegally attacking the P2P software and OS (Operation System) installed in the node and flows out of the distribution control range of the operator. In this case, it is difficult to detect the illegal node. Further, in Patent Document 1, even if an illegal node is found, it is difficult to stop the acquisition of content only by the illegal node.

  The present invention has been made in consideration of such circumstances, and an object of the present invention is to detect a node that illegally uses content in a P2P network that distributes and manages content, and the detected node is a content. It is possible to provide a node device and a computer program that can prevent content from being illegally leaked out of a distribution control range that can be controlled by a business operator by making it impossible to acquire.

[1] According to one aspect of the present invention, a content distribution management system including a plurality of node devices and a network connecting the plurality of node devices is configured, and a node device that manages the location of content is determined according to a predetermined rule. A node list storage unit that stores a node list in which communication addresses of other node devices connected via the network are set, identification information of the other node devices, and content search The relay history storage unit that stores the relay history information that associates the reception time of the request information, the other node device connected via the network, the identification information of the content to be searched and the other node device A communication input unit that receives content search request information including the identification information of the content, and the content received by the communication input unit. The relay history information in which the time at which the search request information is received and the identification information of the other node device read from the content search request information are associated is written in the relay history storage unit, and the relay history storage unit The relay history management unit that acquires the number of relay processes corresponding to the identification information of the other node device from the stored relay history information, and the number of relay processes acquired by the relay history management unit exceeds a predetermined threshold And when the abnormality detection unit determines that the number of relay processes exceeds a predetermined threshold, the identification information of the other node device read from the content search request information Based on the information sending unit to output, the predetermined rule, and the identification information of the content to be searched set in the content search request information, A management node determination unit that determines whether the node device is a node device that manages the location of the search target content, and the abnormality detection unit determines that the number of relay processes does not exceed a predetermined threshold. When the management node determination unit determines that the node device is not a node device that manages the location of the search target content, the node is read from the node list stored in the node list storage unit And a communication output unit that transmits the content search request information with the communication address as a destination.
According to the present invention, when the node device configuring the P2P network receives the content search request information for searching for the location of the content, the identification information of the node device that is the content search request information transmission source, the reception time, Update the relay history information associated with. Then, based on the relay history information, the number of relay processing of the content search request information transmitted in the past from the node device that is the source of the content search request information is obtained, and the threshold value at which the obtained relay processing number is suspected of fraud is set. If it exceeds, the identification information of the node device that is the source of the content search request information is output and the relay is interrupted. If not, the content search request information is relayed.
As a result, in the P2P network, when searching for the location of content, a relay node existing on the path from the node device that has transmitted the content search request information to the node device that manages the location of the content to be searched is suspected of fraud. The node device with a fault is detected, and the identification information of the detected node device is output, so it is possible to notify the administrator of the existence of a node device that is suspected of an illegal node or to check the illegality. At the same time, since the relay of the content search request information is interrupted, the number of illegally acquired contents can be suppressed. It is also possible to limit the number of contents that each node device can acquire on a node device basis.

[2] One aspect of the present invention is the node device described above, in which the abnormality detection unit is illegal in response to the identification information of the other node device output by the information output unit. The content search request information is discarded when the information indicating that the communication output unit is received, and the communication output unit has no fraud corresponding to the identification information of the other node device output by the information output unit. Is received, the content search request information is transmitted with the communication address read from the node list stored in the node list storage unit as a destination.
According to the present invention, when a notification that a node device detected as suspected of fraud is not fraudulent is received, content search request information is relayed, and when a foul notification is received, Discard search request information without relaying it.
As a result, it is possible to control the relay of the content search request information according to the verification result of whether or not the node device detected as suspected of fraud is actually fraudulent.

[3] One aspect of the present invention is the node device described above, wherein the blacklist storage unit that stores the identification information of the unauthorized node device and the identification information of the unauthorized node device are received and received. A black list management unit for writing identification information of the node device to the black list storage unit, wherein the abnormality detection unit is configured such that the identification information of the other node device set in the content search request information is the black list. The content search request information is discarded when stored in the storage unit.
According to the present invention, when the identification information of an unauthorized node device is received, the relay of the content search request information transmitted by the node device specified by the identification information is restricted.
Accordingly, relaying of content search request information transmitted from a specific node device can be restricted at the relay node by a command from a device or the like that manages a plurality of node devices. Therefore, the content acquisition by the node device designated by the service provider can be stopped immediately.

[4] One aspect of the present invention is the node device described above, wherein the communication output unit performs relay history inquiry using the communication address read from the node list stored in the node list storage unit as a destination. The relay history management unit receives the relay history information in response to the relay history inquiry transmitted by the communication output unit, and is stored in the received relay history information and the relay history storage unit The number of relay processes corresponding to the identification information of the other node device set in the content search request information is acquired from the relay history information.
According to the present invention, the relay history is obtained from another relay node, the number of relay processing of the content search request information so far for the node device of the content search request information transmission source is obtained, and whether there is a suspicion of fraud Judgment can be made.
Thereby, even if the relay node of each node device is not fixed, an unauthorized node can be detected.

[5] According to one aspect of the present invention, a content distribution management system including a plurality of node devices and a network connecting the plurality of node devices is configured, and a node device that manages the location of content is determined according to a predetermined rule. A node list storage unit for storing a node list in which a communication address of another node device connected via the network is set, a computer used as the node device, identification information of the other node device, and content A relay history storage unit that stores relay history information in association with the reception time of search request information; from other node devices connected via the network, identification information of content to be searched and the other node devices A communication input unit that receives content search request information including the identification information of the communication, and the communication input unit receives The relay history information in which the time when the content search request information is received and the identification information of the other node device read from the content search request information is associated is written in the relay history storage unit, and the relay history storage A relay history management unit that acquires the number of relay processes corresponding to the identification information of the other node device from the relay history information stored in the unit, and the number of relay processes acquired by the relay history management unit exceeds a predetermined threshold An abnormality detection unit for determining whether the number of relay processes exceeds a predetermined threshold by the abnormality detection unit, the identification information of the other node device read from the content search request information Based on the information transmission unit to be output, the predetermined rule, and the identification information of the search target content set in the content search request information A management node determination unit that determines whether or not the node device is a node device that manages the location of the content to be searched, and the abnormality detection unit determines that the number of relay processes does not exceed a predetermined threshold value. When the management node determination unit determines that the node device is not a node device that manages the location of the search target content, the node is read from the node list stored in the node list storage unit. And a communication output unit that transmits the content search request information with the communication address as a destination.
According to the present invention, when the node device configuring the P2P network receives the content search request information for searching for the location of the content, the identification information of the node device that is the content search request information transmission source, the reception time, Update the relay history information associated with. Then, based on the relay history information, the number of relay processing of the content search request information transmitted in the past from the node device that is the source of the content search request information is obtained, and the threshold value at which the obtained relay processing number is suspected of fraud is set. If it exceeds, the identification information of the node device that is the source of the content search request information is output and the relay is interrupted. If not, the content search request information is relayed.
As a result, in the P2P network, when searching for the location of content, a relay node existing on the path from the node device that has transmitted the content search request information to the node device that manages the location of the content to be searched is suspected of fraud. The node device with a fault is detected, and the identification information of the detected node device is output, so it is possible to notify the administrator of the existence of a node device that is suspected of an illegal node or to check the illegality. At the same time, since the relay of the content search request information is interrupted, the number of illegally acquired contents can be suppressed. It is also possible to limit the number of contents that each node device can acquire on a node device basis.

  According to the present invention, in a P2P network that manages content in a distributed manner, abnormal processing is performed in a relay node that exists on a route from a node device that has transmitted content search request information to a node device that manages the location of the content to be searched. Can detect the node device that is executing, and notify the administrator of the existence of the node device, or can start the processing of validity confirmation. In response to this output, the node device determines whether or not to relay the search request based on the result of checking whether or not the content is actually illegally used. Prevents the content from being acquired, and the number of illegally used content can be reduced.

1 is an overall configuration diagram of a content distribution management system using a P2P network to which the present invention is applicable. It is a figure which shows the example of a setting of a content management list. It is a figure which shows the example of a setting of a node list. It is a figure which shows the content search procedure using a prior art. It is a block diagram which shows the function structure of the node apparatus by 1st Embodiment. It is a block diagram which shows the function structure of the relay control part of the node apparatus by 1st Embodiment. 3 shows an example of relay history information data according to the first embodiment. 4 shows an example of blacklist data according to the first embodiment. The example of a description of the content search request information by 1st Embodiment is shown. The example of a description of the content search reply information by 1st Embodiment is shown. 4 shows a description example of node inquiry information according to the first embodiment. The example of a description of the content storage update information by 1st Embodiment is shown. It is a content download sequence at the time of normal by 1st Embodiment. It is a content download sequence at the time of fraud detection by 1st Embodiment. It is a figure which shows the processing flow in the relay control part of each node apparatus by 1st Embodiment. It is a figure which shows the processing flow in the relay control part of each node apparatus by 1st Embodiment. It is a figure which shows the processing flow in the relay control part of each node apparatus by 1st Embodiment. It is a content download sequence at the time of normal by 2nd Embodiment. It is a content download sequence at the time of fraud detection by 2nd Embodiment. It is a figure which shows the processing flow in the relay control part of each node apparatus by 2nd Embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[1. overall structure]
FIG. 1 shows an overall configuration diagram of a content distribution management system using a P2P network to which the present invention can be applied. The content distribution management system includes a content distribution device 7, a node management device 8, and a license distribution device 9 of a content distribution provider that provides a content distribution service, and a plurality of node devices 1 of each user who enjoys the content distribution service. Consists of Each node device 1 receives content from the content distribution device 7 by broadcast or communication. Further, the node device 1, the node management device 8, and the license distribution device 9 are connected to a communication network N such as the Internet, and can transmit / receive information to / from each other.

  In order to enjoy the content distribution service, the user who owns the node device 1 concludes a contract for service subscription with the content distribution company in advance. Specifically, the node management device 8 (or a contract server not shown) of the content distributor provides a service subscription contract from the user's node device 1 such as personal information of the user and the address of the node device 1. Receive the information you need for. When the contract is concluded between the two parties, the node management device 8 (or the contract server) issues an ID (identifier) for providing the content distribution service and notifies the node device 1 of it. The notified ID is stored in the node device 1 and used as a node ID that uniquely identifies the node device 1. The node management device 8 of the content distribution provider stores the user's personal information received from the node device 1, the address of the node device 1, and the node ID assigned to the node device 1 in association with each other, and uses these information. The user and the node device 1 are managed.

  In the content distribution service, the content distribution company sends a content main body that is digital data of content protected by DRM (Digital Rights Management) from the content distribution device 7 to the node device 1. The content guide, which is data indicating a list of contents, is transmitted. These transmissions may be performed by communication or may be performed by broadcasting. A content ID that is an identifier for specifying the content is assigned to the content body, and the node device 1 identifies the provided content by the content ID. Note that the address of the license distribution device 9 that distributes a license necessary for viewing the content body protected by copyright is notified to the node device 1 together with the node ID when the service subscription contract is concluded.

[2. Data for content distribution management]
2 and 3 are diagrams illustrating examples of lists stored in the node device 1 for managing the content in a distributed manner using a conventional DHT (Distributed Hash Table). Hereinafter, distributed management using Chord, which is a typical DHT algorithm, will be described as an example. In Chord, nodes and contents are arranged in a circular shape in the order of hash values, and the length measured clockwise is defined as the distance in the hash space.

  FIG. 2 shows a content management list, which is a list indicating location information indicating which node device 1 stores content existing in the “neighborhood” of the own node device 1 in the hash space. FIG. 3 shows a node list which is a list indicating information necessary for communication such as the IP address and port of the other node device 1 existing “near” the own node device 1 in the hash space.

  In FIG. 2, the content management list includes a content ID that identifies content whose location information is managed in the node device 1, a hash value of the content ID, a node ID of the node device 1 in which the content is stored, and Information necessary for communication such as the IP address and port number of the node device 1 is described.

  On the other hand, the node list shown in FIG. 3 is necessary for communication such as the node ID of the node device 1 existing in the vicinity of the hash space, the hash value of the node ID, the IP address and the port number of the node device 1. Information is described. The node list may be considered similar to the routing table in DHT. In addition, in order to smoothly perform distributed management by DHT, it is necessary to define the contents to be managed by each node device 1 and the “neighboring” range in the hash space of the transfer destination node device 1 to be grasped. is there. Since the hash value can be calculated from the content ID and the node ID in all the node devices 1, it is not always necessary to describe the hash value in the list.

  2 and 3 show examples in which the hash value of the node ID assigned to the node device 1 is “500” and the range of “neighboring” is “20”. That is, in the content management list, the location of content whose hash value of content ID is in the range of 500 to 520 is managed, and in the node list, the node device 1 whose hash value of node ID is in the range of 500 to 520 is managed. Holds transfer destination information. Note that the neighborhood range based on the hash value of the content ID and the neighborhood range based on the hash value of the node ID may not be the same.

  Hereinafter, the node device 1 whose node ID hash value is X is described as “node device (X)”, and the content whose hash value of content ID is Y is described as “content (Y)”. The node device 1 that transmits the content search request is the transmission node, the node device 1 that relays information is the relay node, the node device 1 that manages the location of the content is the management node, and the node device 1 that stores the content is the node device 1 It is described as an accumulation node.

[3. Content distribution using conventional technology]
Here, the content is broadcast from the content distribution device 7, and the location of the broadcast content is notified to the node device 1, which is the management node of the content, and held in the content management list by the same procedure as before. It shall be.

  FIG. 4 shows a conventional procedure for searching which node device 1 stores desired content in a system that performs distributed management of content using a general DHT. In the figure, the node device 1 whose node ID is “NNNNNN” and the hash value of the node ID is “450”, the content whose content ID is “AAAAAAA” and whose hash value of the content ID is “501”. An example in which the accumulated node apparatus 1 is searched is shown. Here, the neighborhood range is “20”.

(Procedure 1) The node device (450) calculates the hash value “501” from the content ID “AAAAAAA” of the desired content.

(Procedure 2) The node device (450) stores a node list in which information about the node device 1 with the node ID hash values “451”, “455”, and “465” is described. The node device (450) detects the node device (465) identified by the node ID that is the hash value closest to the hash value “501” calculated from the content ID “AAAAAAA” from the node list stored in itself. Then, the address information of the node device (465), that is, the IP address and the port number are read out.

(Procedure 3) The node device (450) sets the content ID “AAAAAAA”, the node ID “NNNNNN”, the IP address “10.2.3.4”, and the port number “5000” of the content to be searched. The search request information is transmitted with the IP address and port number read out in (procedure 2) set as the destination, and notified to the node device (465).

(Procedure 4) Upon receiving the content search request information, the node device (465) calculates a hash value “501” from the content ID “AAAAAAA” set in the content storage update information.

(Procedure 5) Hereinafter, similarly, the operations of (Procedure 2) to (Procedure 4) are repeated to relay the content search request information. That is, the node device 1 detects another node device 1 whose node ID hash value is closest to the hash value calculated from the content ID from the node list stored in itself, and receives the received content search request information. The node device 1 that notifies the detected other node device 1 and receives the content search request information calculates a hash value from the content ID set in the content search request information. By repeating the operations of (Procedure 2) to (Procedure 4), the content search request information is notified to the node device 1 in which the hash value of the node ID falls within the management range 481-501 of the content (501). 4 shows an example in which the node device (500) is notified, but if it is within the management range, the node device (485) and the other node device 1 such as the node device (495) are notified. It doesn't matter.

(Procedure 6) The node device (500) collates the content ID in the content management list stored in itself with the content ID set in the content search request information, and accumulates the requested content. When all the node ID, IP address, and port number pairs of the node device 1 are read, the content search response information in which all the read sets are set is created. In the figure, the content ID “AAAAAAA” of the search target content set in the content search request information, the node ID “000001” read from the content management list, and the IP address “123.123.123.123”. ”And port number“ 5000 ”, node ID“ 000015 ”, IP address“ 111.111.001.002 ”and port number“ 5000 ”, etc. are set. .

(Procedure 7) The node device (500) uses the IP address and port number of the node device (450) described in the content search request information as destinations and sends the content search response information created in (procedure 6) to the node device ( 450).
The node device (450) accesses using the IP address and port number of any node device 1 set in the received content search response information, and acquires the content (501).

As described above, in the content distribution management system in which content is distributed and managed by DHT on the P2P network, each node device 1 grasps only the node device 1 in the vicinity of itself in the hash space. Therefore, in order to search and acquire the location of the content managed in the node device 1 that is not grasped by itself other than the vicinity, it is necessary to relay the search request by one or a plurality of node devices 1. .
Therefore, in the embodiment of the present invention, at the time of content location search, there is a suspicion of fraud at the search request relay node that exists on the route from the originating node to the management node that manages the content location. A certain origination node is detected, and content search is interrupted. Thereby, it is possible to prevent content acquisition itself by an unauthorized node device 1.

[4. First Embodiment]
Next, a first embodiment of the present invention will be described. 1st Embodiment is a case where the relay node used as the destination at the time of transmitting the signal addressed to the node apparatus 1 outside the management range for each node apparatus 1 is fixed. That is, the node device 1 that transmits the content search request information is a node device 1 determined based on a predetermined rule, for example, a number obtained by adding a predetermined number to the hash value of its own node ID becomes the hash value. The node device 1 specified by the node ID is used as a relay node, and content search request information is transmitted. In the present embodiment, it is assumed that content is received by broadcasting.

[4.1 Configuration of node device]
FIG. 5 is a block diagram showing a functional configuration of the node device 1 according to the first embodiment, and only functional blocks related to the present invention are extracted. The node device 1 shown in the figure is realized by a computer device such as a personal computer, a mobile phone, or a television receiver, for example, and includes a broadcast receiving unit 11, a content management unit 12, a content storage unit 13, a download list management unit 14, Download list storage unit 15, content guide management unit 16, content guide storage unit 17, function calculation unit 18, management node condition storage unit 19, transmission destination determination unit 20, transmission destination selection condition storage unit 21, node list management unit 22, A node list storage unit 23, a communication output unit 24, a communication input unit 25, a relay control unit 26, a content management list management unit 27, a content management list storage unit 28, an input unit 29, a display unit 30, and a search unit 31 are included. .

  Specifically, the broadcast receiving unit 11 is a tuner that can receive a broadcast wave, and decodes the content body and the content guide from the received broadcast wave. The communication input unit 25 receives various information transmitted via the communication network N by communication such as the Internet. The communication output unit 24 outputs various types of information via the communication network N to the transfer destination determined by the transmission destination determination unit 20 through communication such as the Internet.

  The content management unit 12 manages content stored in the content storage unit 13. The content storage unit 13 stores the content main body acquired by the broadcast receiving unit 11 or the communication input unit 25. The download list management unit 14 manages the download list stored in the download list storage unit 15. Further, when the storage or deletion of the content in the content storage unit 13 is executed, the content storage update information is generated and transmitted to the communication output unit 24. The download list storage unit 15 stores a download list that is a list of contents stored in the content management unit 12. The content guide management unit 16 manages the content guide stored in the content guide storage unit 17 and provides navigation for allowing the user to view and download the content. In addition, the content guide management unit 16 cooperates with the download list management unit 14 to output information on the content stored in the content management unit 12. The content guide storage unit 17 stores the content guide acquired by the broadcast receiving unit 11 or the communication input unit 25.

  The function calculation unit 18 calculates a hash value of the content ID or node ID using a hash function such as SHA-1 (Secure Hash Algorithm 1) or MD5 (Message Digest 5). Note that the node devices 1 existing in the content distribution management system have a common hash function. The management node condition storage unit 19 stores management node conditions for determining a management node for each content. This management node condition is common to all node devices 1 existing in the content distribution management system. The transmission destination selection condition storage unit 21 stores a transmission destination selection condition for selecting an information transmission destination node device 1, that is, a relay node. This transmission destination selection condition is common to all the node devices 1 belonging to the content distribution management system. The transmission destination determination unit 20 determines a transmission destination of information to be transmitted by the communication output unit 24 according to the conditions stored in the management node condition storage unit 19 or the transmission destination selection condition storage unit 21. The node list management unit 22 manages the node list stored in the node list storage unit 23. The node list storage unit 23 stores the same node list as in FIG.

  The relay control unit 26 performs control for further relaying the content storage update information and content search request information received from the other node device 1 to the other node device 1. At this time, when receiving the content search request information, the relay control unit 26 determines whether or not to execute the relay process based on the black list and the relay history of the content search request information. When the node device 1 functions as a management node, the relay control unit 26 generates content search answer information based on the content search request information and the content management list in the content management list storage unit 28.

  When the own node device 1 functions as a content management node, the content management list management unit 27 stores content management stored in the content management list storage unit 28 based on the content storage update information received from the other node device 1. Update the list and manage the content management list. In addition, the content management list management unit 27 periodically exchanges the content management list with the nearby node device 1 to perform collation, and keeps the content list up-to-date. The content management list storage unit 28 stores a content management list having a data configuration similar to that shown in FIG.

  The input unit 29 is an interface between the node device 1 and the user, and inputs a user operation in the content guide. The input unit 29 is a device such as a remote controller or a button, for example. The display unit 30 is specifically a display, and displays a content body and a content guide that can be viewed according to the license information acquired from the license distribution device 9. The search unit 31 generates content search request information when receiving a download request for content stored in the other node device 1 from the content guide management unit 16.

  FIG. 6 is a block diagram illustrating a functional configuration of the relay control unit 26 of the node device 1. In the figure, the relay control unit 26 includes an information reception unit 41, an abnormality detection unit 42, a relay history management unit 43, a relay history storage unit 44, a black list management unit 45, a black list storage unit 46, a management node determination unit 47, A content search response information generation unit 48, a content management list collation unit 49, a node inquiry information generation unit 50, and an information transmission unit 51 are provided.

  The information receiving unit 41 receives content search request information, content accumulation update information, and the like from the communication input unit 25. Corresponding to the node ID of the calling node read from the content search request information, the abnormality detecting unit 42 acquires the number of search processes of the calling node, that is, the number of searched contents, from the relay history management unit 43 and sets it in advance. An abnormality is detected based on the threshold value.

  The relay history management unit 43 manages the relay history information stored in the relay history storage unit 44. The relay history storage unit 44 is a database that stores relay history information indicating the node ID of the transmission node of the content search request information processed by the abnormality detection unit 42 and the reception time of the content search request information. The black list management unit 45 manages the black list stored in the black list storage unit 46. The black list storage unit 46 stores a black list that is a list of node IDs of the node devices 1 that are recognized as illegal by the content distribution company.

  The management node determination unit 47 determines whether or not the own node device 1 is a management node based on the management node condition stored in the management node condition storage unit 19, and based on the determination result, the received content search request information It is determined whether or not relay of content storage update information or the like is necessary. The content search response information generation unit 48 generates content search response information when the node device 1 is a management node of the content to be searched by the content search request information. The content management list collation unit 49 collates the content management list stored in the content management list storage unit 28 with the content ID of the content to be searched based on the content search request information. When an abnormality is detected by the abnormality detection unit 42, the node inquiry information generation unit 50 generates node inquiry information for inquiring the node management device 8 about the validity of the node. The information transmission unit 51 transfers various information to be transmitted via the communication network N to the communication output unit 24.

[4.2 Data description example]
FIG. 7 shows an example of relay history information data stored in the relay history storage unit 44 of the node device 1. In the figure, the relay history information is composed of a plurality of records including the node ID of the node device 1 that is the transmission node of the content search request information and the reception time of the content search request information.

  FIG. 8 shows an example of blacklist data stored in the blacklist storage unit 46 of the node device 1. In the figure, the black list indicates a list of node IDs of the unauthorized node device 1.

  Next, description examples of content search request information, content search response information, node query information, and content storage update information transmitted or received by the node device 1 are shown. In order to unify the interpretation of data in the plurality of node devices 1, a common format is used for these pieces of information and is described in an extensible markup language (XML) format that is a general-purpose language.

  FIG. 9 shows a description example of content search request information. In the same figure, in order to distinguish the type of data, the type indicating content search request information is described at the top of the data of the content search request information. Further, in the content search request information body, the content ID of the content whose location is to be searched, the node ID, IP address and port number of the node device 1 that has transmitted the content search request information, and the content search The source node information including the time stamp of the time at which the request information is transmitted is described.

  FIG. 10 shows a description example of content search response information. The content search response information is generated as a response to the content search request information shown in FIG. In the figure, in order to distinguish the types of data, a type indicating content search response information is described at the top of the data of content search response information. Further, the content search response information body includes a content ID of the content to be notified of the location, and a list of the node ID, IP address, and port number of the node device 1 that stores the content of the content ID. Storage node information is described.

  FIG. 11 shows a description example of node inquiry information. In the figure, in order to distinguish the type of data, the type of node inquiry information is described at the head of the data of the node inquiry information. Furthermore, the main body of the node inquiry information includes a node ID, an IP address, and a port number of the node device 1 to be inquired, and the number of relay processes of the content search request information that uses the node device 1 as a transmission node. Node information is described.

  FIG. 12 shows a description example of content storage update information. In the figure, in order to distinguish the type of data, a type indicating content storage update information is described at the head of the data of content storage update information. Further, the content storage update information body includes a content ID of the content to be updated, a node ID, an IP address and a port number of the node device 1 that transmits the content storage update information, and the content storage update information. Node information including the time stamp of the time when the message is transmitted is described.

[4.3 Processing procedure for the entire system when downloading contents]
First, when the content is broadcast from the content distribution device 7, the node device 1 that has accumulated the content notifies the management node of the content that the content has been accumulated by the same procedure as before.
Specifically, when the broadcast receiving unit 11 of the node device 1 receives a content body and a content guide by broadcasting from the content distribution device 7, the content management unit 12 writes the content body into the content storage unit 13 and download list management. The unit 14 writes the content ID of the content written in the content storage unit 13 in the download list storage unit 15, and the content guide management unit 16 writes the content guide in the content guide storage unit 17. When the content body is stored, the function calculation unit 18 of the node device 1 acquires the content ID assigned to the received content body and calculates a hash value of the content ID. Based on the management node condition stored in the management node condition storage unit 19, the download list management unit 14 determines whether the own node device 1 is a content management node from the calculated hash value of the content ID. For example, when the management node condition indicates the neighborhood range, the hash value of the content ID is X, and the neighborhood range is Y, the management node in which the node devices (X−Y + 1) to (X) manage the content (X). It is.

When the hash value of the own node ID is not included in the range of (X−Y + 1) to (X), the download list management unit 14 sets the type indicating content storage update information and the content management unit 12. Content storage update information describing the content ID of the stored content, the node ID of the own node device, the IP address and port number, and the source node information consisting of the time stamp in which the current time is set is generated. Then, the communication output unit 24 transmits the content accumulation update information with the IP address and port number of the relay node acquired by the transmission destination determination unit 20 as the destination by the same processing as the transfer of the content search information described later.
Further, processing when the node device 1 that is the destination of the content storage update information receives the content storage update information will also be described later.

  FIG. 13 shows a normal content download sequence according to this embodiment. Here, there is one relay node for the content search request information from the content search request information transmission node to the management node for managing the search target content. In addition, it is assumed that the relay node does not detect fraud or abnormality and the content main body has been downloaded normally.

  Hereinafter, the node device 1a is a source node that requests content download, the node device 1 is a relay node that relays content search request information transmitted from the node device 1a, and the location of the content requested by the node device 1a A management node that manages the content is a node device 1c, and a storage node that stores a content body of content requested by the node device 1a is a node device 1d.

  Content download instruction (step S105): The user of the node device 1a inputs an instruction to display the content guide distributed from the content distribution device 7 through the input unit 29. The display unit 30 of the node device 1 a causes the display unit 30 to display content information read from the content guide storage unit 17 by the content guide management unit 16. When the user browses the displayed content guide and decides to download the content, the user inputs a download request to the input unit 29. The content guide management unit 16 of the node device 1a outputs the content ID of the content to be downloaded to the search unit 31.

  The search unit 31 of the node device 1a generates content search request information in which the content ID received from the content guide management unit 16 and its own node ID and address information are set, and transmits the content search request information to the communication output unit 24. Outputs the content ID to the transmission destination determination unit 20. The transmission destination determination unit 20 refers to the transmission destination selection condition stored in the transmission destination selection condition storage unit 21 and determines the relay destination of the content search request information. For example, it is assumed that the transmission destination selection condition indicates that the value obtained by adding B to the hash value of the own node ID is the hash value of the node ID of the node device 1 to be selected. In this case, the transmission destination determination unit 20 transfers the node device (A + B) specified by the node ID in which the value obtained by adding the addition value “B” to the hash value “A” of the node ID of the node device 1a is the hash value. Decide as a destination. The transmission destination determination unit 20 reads the node device (A + B), that is, the IP address and port number of the node device 1b from the node list from the node list stored in the node list storage unit 23. The communication output unit 24 of the node device 1a transmits the content search request information with the IP address and port number read by the transmission destination determination unit 20 as destinations.

  Relay control (step S110): The communication input unit 25 of the node device 1b receives the content search request information from the node device 1a and transfers it to the relay control unit 26. The relay control unit 26 of the node device 1b acquires the node ID of the node device 1a from the received content search request information, and determines whether the acquired node ID is not included in the black list. When the node ID of the node device 1a is included in the black list, the content search request information is discarded. On the other hand, when the node ID of the node device 1a is not included in the black list, the relay control unit 26 of the node device 1b updates the relay history information and refers to the updated relay history information for a certain time until the present time. When the node device 1a, which has been processed by the node device 1b, obtains the number of relay processes for the content search request of the transmission source, it determines whether the obtained number of relay processes exceeds a predetermined threshold. When the number of relay processes is equal to or less than a predetermined threshold, the relay control unit 26 of the node device 1b determines whether it is a management node. When determining that the node is not a management node, the relay control unit 26 determines to transfer the received content search request information. When the transmission destination determination unit 20 of the node device 1b obtains the hash value of the content ID of the management node from the management node condition stored in the management node condition storage unit 19 and the hash value of the content ID, the node list storage unit 23 reads out the IP address and port number of the node device 1c specified by the hash value of this management node from the node list stored in the node 23, and transfers the content search request information with the read IP address and port number as the destination. .

  Content location notification (step S115): The communication input unit 25 of the node device 1c receives the content search request information from the node device 1b. When the relay control unit 26 of the node device 1c determines that it is a management node, it is set in the content ID in the content management list stored in the content management list storage unit 28 and the received content search request information. When all the combinations of the node ID, IP address, and port number of the node device 1 that stores the requested content are read out, all the sets that have been read are set as storage node information. Create search response information. The communication output unit 24 of the node device 1c transmits the content search response information created by the relay control unit 26 with the IP address and port number of the node device 1a described in the content search request information as destinations.

  Content download (step S120): The communication input unit 25 of the node device 1a receives content search response information from the node device 1c. The search unit 31 of the node device 1a generates a content download request in which the content ID of the content requesting download, its own node ID, and address information are set, and the communication output unit 24 receives the generated content download request. The IP address and port number of the node device 1d selected from the storage node information described in the content search request information are transmitted as the destination.

  Content upload (step S125): The communication input unit 25 of the node device 1d receives a download request from the node device 1a. The content management unit 12 of the node device 1d acquires the content ID from the received download request, and reads the content body specified by the acquired content ID from the content storage unit 13. The communication output unit 24 of the node device 1d transmits the content body read by the content management unit 12 with the address information of the node device 1a that is the transmission source of the download request as the destination.

  Download completion (step S130): The communication input unit 25 of the node device 1a receives the content body from the node device 1d. The content management unit 12 of the node device 1 a writes the content body into the content storage unit 13, and the download list management unit 14 writes the content ID of the content written into the content storage unit 13 into the download list storage unit 15. The download list management unit 14 of the node device 1a generates content accumulation update information in which the content ID of the downloaded content main body and its own node ID, IP address, and port number are set, and the communication output unit 24 is generated. The content storage update information is transmitted to the node device 1c that is the transmission source of the content search response information.

  Content management list update (step S135): The communication input unit 25 of the node device 1c receives the content storage update information from the node device 1a. When the relay control unit 26 of the node device 1c determines that it is a management node based on the content ID acquired from the content storage update information, the content management list management unit 27 transmits the transmission read from the content storage update information A record in which the node ID, IP address, and port number in the node information and the hash value of the content ID calculated by the function calculation unit 18 are set is written in the content management list stored in the content management list storage unit 28. .

  The download list management unit 14 of the node device 1a notifies the license distribution device 9 of the content ID of the downloaded content body and the node ID of the own node device 1a, and obtains license information for decoding the content body. To do. The license distribution device 9 stores the node ID of the node device 1a in association with the content ID of the content that transmitted the license information. The content management unit 12 of the node device 1a writes the received license information in the content storage unit 13, and the download list management unit 14 writes the content ID of the content in which the license information is written in the content storage unit 13 in the download list storage unit 15. .

  FIG. 14 shows a content download sequence when fraud is detected.

  Download request (step S205): The node device 1a transmits content search request information to the node device 1b by the same processing as step S105 in FIG.

  Relay control (step S210): The node device 1b determines whether the node ID of the node device 1a is not included in the black list by the same processing as step S110 in FIG. The number of relay processes within a certain time until the present time of the content search request information to be obtained is obtained, and it is determined whether or not a predetermined threshold is exceeded. When the number of relay processes exceeds a predetermined threshold, the relay control unit 26 of the node device 1b determines that the node device 1a is suspected of fraud. The relay control unit 26 of the node device 1b obtains the total number of relays processed from the relay history information to the current content search request information originating from the node device 1a, and reads the content ID read from the content search request information, Generate node query information that sets the total number of relay processes. The communication output unit 24 of the node device 1 a transmits the node inquiry information generated by the relay control unit 26 to the node management device 8.

  Fraud investigation (step S215): The node management apparatus 8 transmits a license acquisition number inquiry with the address information of the node apparatus 1a set in the node inquiry information received from the node apparatus 1b as a destination. The download list management unit 14 of the node device 1a acquires the number of license information stored in the download list storage unit 15, and the communication output unit 24 determines the number of license information obtained by the download list management unit 14, that is, The node management device 8 is notified of the number of licenses acquired. Further, the node management apparatus 8 transmits a license provision number inquiry in which the node ID of the node apparatus 1a is set to the license distribution apparatus 9. The license distribution device 9 notifies the node management device 8 of the number of provided licenses corresponding to the node ID set in the license provision number inquiry.

  Fraud confirmation (step S220): The node management device 8 compares the number of licenses received from the node device 1a with the number of relay processes set in the node inquiry information received from the node device 1b, and a divergence greater than a predetermined value. Determine if there is. If there is a divergence more than a predetermined value, it is determined that the node device 1a is an unauthorized node. Also, the node management device 8 compares the number of license distributions to the node device 1a received from the license distribution device 9 with the number of relay processes set in the node inquiry information received from the node device 1b, and exceeds a predetermined value. If there is a divergence, it is determined that the node device 1a is an unauthorized node. If it is determined that the node is an unauthorized node, the node management device 8 returns a black list in which the node ID of the node device 1a read from the node inquiry information is set to the node device 1b that is the transmission source of the node inquiry information.

  Unauthorized node grasp (step S225): The communication input unit 25 of the node device 1b receives the black list from the node management device 8. The relay control unit 26 of the node device 1b relays the received content search request information when recognizing that the node device 1a is an unauthorized node because the node ID of the node device 1a is set in the black list. Discard without. Further, the relay control unit 26 of the node device 1b adds the node ID of the node device 1a described in the received black list to the currently held black list.

  If it is confirmed in step S220 that the information is not illegal, the node management device 8 transmits the notification information indicating that there is no fraud to the node device 1b of the relay node. In this case, the node device 1b performs the processing subsequent to the determination processing as to whether or not the node device 1b is a management node in step S110 of FIG. Relay content search request information.

  In step S220, the node management device 8 compares the number of licenses acquired and the number of relay processes. Alternatively, user information corresponding to the node ID described in the node inquiry information may be output to a screen or the like. Good. In this case, the content distributor confirms whether fraud has been performed by making an inquiry to the user based on the output user information. Then, the result is input to the node management device 8. With this input, the node management device 8 returns a black list or no-notification notification information to the node device 1b. In step S220, the black list may be distributed not only to the node device 1b of the relay node but also to all the node devices 1.

  As described above, when each node device 1 receives the content search request information from the other node device 1, first, the node device 1 checks whether or not the node device 1 is an unauthorized node based on the black list. If the node is an unauthorized node, the content search request information relay process is not executed, thereby making it impossible to acquire the content by the unauthorized node. On the other hand, even if the node is not confirmed as an unauthorized node, the relay history information is recorded for each node device 1 each time content search request information is transmitted, and the possibility of an unauthorized node is determined based on the number of relay processes within a certain time. A certain abnormal node device is detected. When an abnormality is detected in the relay node, the node inquiry information is transmitted to the node management apparatus 8 of the content distributor and the inquiry is requested. The content distribution company communicates with the node device 1 in which an abnormality is detected or its user, and confirms the fact of fraud. When fraud is confirmed, information indicating that the fraudulent node is added to the black list is transmitted to the relay node in order to make it impossible for the fraudulent node to acquire the content.

  In the case of a content distribution service protected by DRM, the user generally obtains a license from the license distribution device 9 managed by the content distribution company when viewing the content. The license distribution device 9 manages the license acquisition status for each node device 1. Since a normal user searches for the location of the content in consideration of viewing the content and acquires the content body, the number of licenses acquired per node device 1 is the same as the number of content searches and the number of content bodies acquired. It is possible. Therefore, if the number of content searches exceeds the number of licenses acquired, the user may be taking an unusual usage method. Therefore, the content distribution company can use the difference between the number of content searches and the number of licenses acquired as an index for detecting unauthorized use when a query is requested from the relay node.

  If the distance in the hash space is large from the node device 1 that has transmitted the content search request information to the management node of the content to be searched, the content search request information reaches the management node via one or more node devices 1 It will be. At this time, the relay control unit 26 of the node device 1 serving as the first relay node performs processing for detecting an unauthorized node. For example, the node ID of the source node set in the received content search request information is read, and the node ID of the relay destination of the node ID determined from the destination selection condition stored in the destination selection condition storage unit 21 Can be determined to be the first relay node when the node ID is its own node ID.

15 to 17 are diagrams illustrating a processing flow in the relay control unit 26 of the node device 1.
15, the information receiving unit 41 of the node device 1 determines the type of information received by the communication input unit 25 via the communication network N (step S305).
When the received information is content search request information (step S305: content search request information), the abnormality detection unit 42 reads the node ID described in the content search request information (step S310). The abnormality detection unit 42 searches the black list stored in the black list storage unit 46 based on the node ID of the read source node, and checks whether it is registered (step S315).

  If the node ID of the calling node is registered in the black list (step S320: Yes), the node device 1 ends the process. Therefore, the content search request information is not transferred but discarded. When the node ID of the transmission node is not registered in the black list (step S320: No), the abnormality detection unit 42 transfers the node ID of the transmission node to the relay history management unit 43 (step S325). The relay history management unit 43 associates the node ID of the transmission node with the content search request information reception time indicating the current time and adds it to the relay history information stored in the relay history storage unit 44 (step S330). The relay history management unit 43 determines from the relay history information stored in the relay history storage unit 44 that the received node ID of the originating node and the content search request information reception time indicating a time within a predetermined time from the current time. When the set record is specified and the number of the specified records is obtained as the number of relay processes within a predetermined period up to the present, the number of relay processes is transferred to the abnormality detection unit 42 (step S335).

  In FIG. 16, the abnormality detection unit 42 determines whether the number of relay processes within a predetermined period received from the relay history management unit 43 exceeds a threshold value (step S340). If the threshold value is not exceeded (step S340: NO), then the management node determination unit 47 determines whether or not the own node device 1 is the management node of the search target content (step S345). Specifically, the management node determination unit 47 outputs the content ID read from the content search request information to the function calculation unit 18, and the function calculation unit 18 calculates the hash value of the received content ID to determine the management node. To the unit 47. The management node determination unit 47 determines whether the own node device 1 is the management node of the content from the calculated hash value and the management node condition read from the management node condition storage unit 19. For example, when the hash value of the content ID is X and the range of the management node read from the management node condition storage unit 19 is Y, the hash value of the own node ID is included in the range of (X−Y + 1) to (X). If so, it is determined that the own node device 1 is a management node.

  When it is determined that the own node device 1 is a management node (step S345: Yes), the abnormality detection unit 42 transfers the content search request information to the content search answer information generation unit 48 (step S350). The content search answer information generating unit 48 outputs the content ID read from the content search request information to the content management list matching unit 49, and the content management list matching unit 49 stores the content management stored in the content management list storage unit 28. In the list, all the records in which the received content IDs are set are specified, and the combination of the node ID, IP address and port number of the storage node is read from the specified records and returned to the content search response information generating unit 48 (step) S355).

  The content search response information generation unit 48 includes the message type in which the content search response information is set, the content ID read from the content search request information, the node ID and IP address of the storage node received from the content management list matching unit 49 When the content search response information in which the set of the port number and the port number are set is generated, the IP address and the port number read from the transmission node information of the content search request information are set as the destination and output to the information sending unit 51 (step S360). . The information sending unit 51 transfers the received content search response information to the communication output unit 24 (step S365), and the communication output unit 24 sends the content search response information to the content search request information transmission source via the communication network N. Transmit to the node device 1.

  On the other hand, when the node itself is not a management node (step S345: No), the abnormality detection unit 42 transfers the received content search request information to the information transmission unit 51 (step S370), and the information transmission unit 51 performs the content search. The request information is transferred to the communication output unit 24 (step S365). The communication output unit 24 outputs the content ID acquired from the content search request information to the transmission destination determination unit 20. When determining the management node from the management node condition stored in the management node condition storage unit 19 and the hash value of the content ID, the transmission destination determination unit 20 determines from the node list stored in the node list storage unit 23, The IP address and port number of the node device 1 of the selected management node are read from the node list. The communication output unit 24 transfers the content search request information with the IP address and port number read by the transmission destination determination unit 20 as destinations.

  In step S340, when it is determined that the number of relay processes within the predetermined period exceeds the threshold (step S340: Yes), the relay history management unit 43 displays the number of records in which the node ID of the caller node is currently set. Is acquired as the number of relay processes up to and output to the anomaly detection unit 42. The anomaly detection unit 42 determines the node ID, IP address, and port number of the originating node and the number of relay processes received from the relay history management unit 43 as a node. It transfers to the inquiry information generation part 50 (step S375). The node inquiry information generation unit 50 includes the inquiry node information in which the node ID, IP address and port number of the transmission node and the number of relay processes are set, and generates node inquiry information in which the address of the node management device 8 is set as the destination Then, the information is output to the information sending unit 51 (step S380). The information sending unit 51 transfers the received node inquiry information to the communication output unit 24 (step S365), and the communication output unit 24 sends the node inquiry information to the node management apparatus 8 via the communication network N.

  Upon receiving the node inquiry information, the node management device 8 conducts an unauthorized investigation of the node device 1 specified by the node inquiry information, and returns no-notification notification information or a black list as an unauthorized confirmation indicating the result.

In step S395 in FIG. 15, if the received information is notification information without fraud (step S305: notification information without fraud), the processing from step S345 in FIG. 16 is performed.
When the received information is a black list (step S305: black list), the information reception unit 41 transfers the received node inquiry response information to the black list management unit 45 (step S390). The black list management unit 45 adds the node ID read from the black list set in the node inquiry response information to the black list stored in the black list storage unit 46 (step S395), and ends the process. Therefore, the content search request information is not transferred but discarded.

FIG. 17 is a flow when it is determined in step S305 of FIG. 15 that the type of received information is content storage update information.
When the information receiving unit 41 determines that the type of received information is content storage update information (step S305: content storage update information), the management node determination unit 47 performs the same process as in step S345 described above. It is determined whether the node device is the content management node (step S400).

  If it is determined that the own node device 1 is a management node (step S400: Yes), the information receiving unit 41 transfers the content storage update information to the content management list management unit 27 (step S405). The content management list management unit 27 updates the content management list stored in the content management list storage unit 28 based on the content accumulation update information. That is, if the content ID set in the content storage update information is not yet registered in the content management list, the content management list management unit 27 sets the content ID and the content ID calculated by the function calculation unit 18. Register the hash value. Further, the content management list management unit 27 registers a set of the node ID, IP address, and port number of the source node information read from the content storage update information in the content management list in association with the content ID.

  When it is determined that the own node device 1 is not a management node (step S400: No), the information reception unit 41 outputs the content accumulation update information to the information transmission unit 51 (step S410). Then, returning to FIG. 16, the information sending unit 51 transfers the received content storage update information to the communication output unit 24 (step S365). When the transmission destination determination unit 20 determines a management node from the management node condition stored in the management node condition storage unit 19 and the hash value of the content ID in the content storage update information calculated by the function calculation unit 18, From the node list stored in the list storage unit 23, the IP address and port number of the node device 1 determined as the management node are read from the node list, and the communication output unit 24 is read by the transmission destination determination unit 20 The content storage update information is transferred with the IP address and port number as the destination.

  As described above, an example of distributed management of content on a P2P network in a broadcast download service has been described. However, the node device 1 and the system are the same not only for broadcast but also for content distribution by wired or wireless communication. By taking the configuration, the same function can be realized.

[5. Second Embodiment]
Next, a second embodiment of the present invention will be described. The second embodiment is a case where the node device 1 has a plurality of relay nodes that are destinations when transmitting a signal addressed to the node device 1 outside the management range of the node device 1. When the relay node is fixed as in the first embodiment, if the node device 1 serving as the relay node leaves the network, a node device 1 that cannot search and download content is generated. Therefore, by performing relaying in any of a plurality of nearby node devices 1 that each node device 1 grasps, reliability in information transmission can be improved.

In the first embodiment, since relay nodes are fixed for each node, management of all relay history information of one node device 1 can be realized by one relay node. On the other hand, in the second embodiment, since the relay history information is distributed to a plurality of node devices 1, a process for integrally processing the distributed relay history information is required.
Below, the difference with 1st Embodiment is demonstrated.

[5.1 Configuration of node device]
The configuration of the node device 1 according to the present embodiment is the same as that of the first embodiment shown in FIGS. However, the transmission destination selection condition storage unit 21 stores transmission destination selection conditions from which a plurality of relay destinations can be selected. The relay history management unit 43 further has a function of inquiring relay history information to the nearby node device 1.

[5.2 Processing Procedure of Entire System at Content Download]
FIG. 18 shows a normal content download sequence according to this embodiment. Here, the node device 1a includes a plurality of neighboring node devices 1 in the hash space that can serve as relay nodes. Among the neighboring node devices 1, the node device 1 that serves as a relay node for content search request information is designated as a node. A node device 1 other than the device 1b and the relay node is referred to as a node device 1b ′. In the figure, only one node device 1b ′ is shown, but a plurality of node devices 1b ′ may exist.
Since the node device 1b and the node device 1b ′ are included in the vicinity of the hash space of the node device 1a, the node device 1b and the node device 1b ′ are also the node devices 1 in the vicinity of the hash space. That is, the information of the node device 1b ′ is registered in the node list of the node device 1b, and the information of the node device 1b is registered in the node list of the node device 1b ′.

  In this embodiment, for the node device (X), the range in the vicinity of the hash space indicated by the destination selection condition is N, that is, the node devices 1 that can be relay nodes are the node devices (X + 1) to (X + N), The neighboring node devices 1 on the hash space held in the node list are assumed to be node devices (X−N + 1) to (X + N). Thereby, even when the content search request information is transmitted to the relay node having the longest distance in the hash space, the relay node sends the relay history information to the node device 1 that can be selected as the relay node by the node device (X). You can inquire.

For example, when the hash value of the node ID of the node device 1a is A, any of the node device (A + 1) to the node device (A + N) is used as a transfer destination when transmitting information to the node device 1 that is not in the vicinity range. Is selected as a relay node. When the node device 1a selects the node device (A + N) as the relay node, the selected node device (A + N), that is, the node device 1b is another node device (A + 1) that the node device 1a can select as the relay node. ) To the node device (A + N−1), the relay history information can be inquired. Further, the node device 1b relays any one of the node device ((A + N) +1) to the node device ((A + N) + N) as a transfer destination when transmitting information to the node device 1 that is not in the vicinity range. Choose as. That is, the node device 1b grasps the node device (A + 1) to the node device (A + 2N) as neighborhoods. Here, if (A + N) = X, as described above, the node device (X) grasps the node device (X−N + 1) to the node device (X + N) as neighbors.
However, the node device (X) normally has a high probability of selecting the neighboring node device 1 that is the most distant from itself in the hash space as a relay node. Therefore, the node device (X) may set the node device node device (X−N + i) to the node device (X + N) (1 <i <(N−1)) in the vicinity range. For example, i can be determined from statistical results so that a range selected as a relay node with a probability equal to or higher than a predetermined value is included.

  Download instruction (step S605): By the same procedure as step S105 in FIG. 13, when the search unit 31 of the node device 1a receives the content ID of the content requested to be downloaded from the content guide management unit 16, the received content ID, Content search request information in which its own node ID and address information are set is generated and transmitted to the communication output unit 24, and the content ID is output to the function calculation unit 18. When the transmission destination determination unit 20 of the node device 1a reads the transmission destination selection condition from the transmission destination selection condition storage unit 21, it is registered in the node list stored in the node list storage unit 23, and the transmission destination Among the node devices 1 that match the selection condition, the node device 1 having the node ID that is the closest to the hash value of the content ID calculated by the function calculation unit 18 is selected as a relay node, and the selected relay node Read IP address and port number. Alternatively, the node device 1 having the node ID that has the hash value closest to the hash value of the content ID calculated by the function calculation unit 18 may be selected as a relay node from among those registered in the node list. The communication output unit 24 of the node device 1a transmits the content search request information with the IP address and port number read by the transmission destination determination unit 20 as destinations.

  Relay history provision (step S610): The communication input unit 25 of the node device 1b receives the content search request information from the node device 1a. The relay control unit 26 of the node device 1b acquires the node ID of the node device 1a from the received content search request information, and determines whether the acquired node ID is not included in the black list. When the node ID of the node device 1a is included in the black list, the content search request information is discarded. On the other hand, when the node ID of the node device 1a is not included in the black list, the relay control unit 26 of the node device 1b further sets the relay history information stored in itself and the relay history in which the node ID is set. Inquiry information is generated and output to the communication output unit 24. The transmission destination determination unit 20 reads the IP address and port number of the node device 1b ′ in the vicinity thereof from the node list stored in the node list storage unit 23. At this time, the node device 1b ′ that can be selected as the relay node is specified based on the node ID of the node device 1a and the transmission destination selection condition in the transmission destination selection condition storage unit 21, and the IP address and the port number are read out. Good. The communication output unit 24 of the node device 1b transmits the relay history inquiry information with the IP address and port number of the node device 1b 'read by the transmission destination determination unit 20 as a destination.

  Relay history information update / inquiry (step S615): The communication input unit 25 of the node device 1b 'receives the relay history inquiry information from the node device 1b. The relay control unit 26 stores the relay history information read from the relay history inquiry information in association with the node ID of the node device 1b. Further, when the relay control unit 26 of the node device 1b 'reads the relay history information stored in itself, the relay control unit 26 generates relay history update information in which the read relay history information and its node ID are set. The communication output unit 24 of the node device 1b 'transmits the relay history update information generated by the relay control unit 26 to the node device 1b that is the transmission source of the relay history inquiry information.

  Relay history update (step S620): The communication input unit 25 of the node device 1b receives the relay history update information from the node device 1b '. The relay control unit 26 of the node device 1b stores the relay history information read from the relay history update information in association with the node ID of the node device 1b '.

  Relay control (step S625): The relay control unit 26 of the node device 1b determines the node ID of the node device 1a and the time within a predetermined time from the relay history information of the node device 1b and the relay history information of the node device 1b ′. When the record for which the content search request information reception time indicating the number is set and the number of the specified records is obtained as the total number of relay processes within a predetermined time, the number of relay processes is output to the abnormality detection unit 42 To do. When the abnormality detection unit 42 determines that the number of relay processes within a predetermined time is equal to or less than a predetermined threshold, the relay control unit 26 of the node device 1b transfers the received content search request information to the communication output unit 24. Instruct. Selection of the transfer destination is the same as the processing when the node device 1a determines the relay node of the content search request information in step S605. In other words, the transmission destination determination unit 20 of the node device 1b has the node ID of the node device 1 registered in the node list and having the hash value closest to the hash value of the content ID among the node devices 1 that match the transmission destination selection condition. The device 1 is selected as a relay node, or the node device 1 with the node ID that is the hash value closest to the hash value of the content ID is selected as a relay node from among those registered in the node list, and the IP address and port number Is read. The communication output unit 24 of the node device 1b transmits the content search request information to the node device 1c with the IP address and the port number read by the transmission destination determination unit 20 as destinations.

  The processing after step S630 is the same as the processing after step S115 in FIG.

FIG. 19 shows a content download sequence sequence when fraud is detected according to the present embodiment.
In the figure, the processing from step S705 to step S720 is the same as the processing from step S605 to step S620 in FIG.

  Relay control (step S725): The node device 1b outputs the total number of relay processes within a predetermined time of the node device 1a obtained in the same manner as in step S625 of FIG. When the number of relay processes within a predetermined time exceeds a predetermined threshold, the abnormality detection unit 42 determines that the node device 1a is suspected of fraud. The relay control unit 26 of the node device 1b sets the content ID read from the content search request information and the number of relay processes to date obtained from the relay history information of the node device 1b and the relay history information of the node device 1b ′. The node inquiry information is generated, and the communication output unit 24 transmits the node inquiry information generated by the relay control unit 26 to the node management device 8.

  The processes in steps S730 to S745 are the same as the processes in steps S215 to 225 in FIG. However, in step S735, the node management device 8 also transmits the black list in which the node ID of the node device 1a is set to the node device 1b and the node device 1b '.

Unauthorized Node Understanding (Step S750): The communication input unit 25 of the node device 1b ′ receives the black list from the node management device 8. The relay control unit 26 of the node device 1b ′ adds the node ID of the node device 1a described in the black list received from the node management device 8 to the currently held black list.
In this way, the blacklist is updated in a plurality of neighboring node devices 1 that can be relay nodes of the node device 1a, thereby making it impossible to acquire content by an unauthorized node.

  Each node device 1 manages the latest relay history information by periodically transmitting and receiving and updating the relay history information. That is, the relay history management unit 43 of each node device 1 periodically uses the relay history information read from the relay history storage unit 44 with the neighboring node devices 1 using the address information stored in the node list as the destination. Send and receive. The relay history management unit 43 of each node device 1 writes and updates the relay history information received from the other node devices 1 in the relay history storage unit 44.

  FIG. 20 is a diagram illustrating a processing flow in the relay control unit 26 of the node device 1 according to the present embodiment. Below, the difference with the processing flow of 1st Embodiment shown in FIGS. 15-17 is demonstrated.

In the figure, the information receiving unit 41 of the node device 1 determines whether the type of received information is content search request information, content storage update information, or relay history query information (step S805). .
If the received information type is content search request information in step S805, the same processing as in steps S310 to S330 in FIG. 15 is performed (steps S810 to S830).

  Subsequently, the relay history management unit 43 of the node device 1 generates relay history information stored in the relay history storage unit 44 and relay history inquiry information in which its own node ID is set, and outputs it to the communication output unit 24. (Step S835). The transmission destination determination unit 20 reads out the IP address and port number of the node device 1 in the vicinity thereof or the node device 1 that the transmission node can select as a relay node from the node list stored in the node list storage unit 23. . The communication output unit 24 of the node device 1b transmits the relay history inquiry information with the IP address and port number of the node device 1 read by the transmission destination determination unit 20 as destinations.

  The communication input unit 25 receives the relay history update information from the other node device 1 via the communication network N, and outputs it to the information receiving unit 41 (step S840). The information receiving unit 41 outputs the relay history update information to the relay history management unit 43, and the relay history management unit 43 associates the relay history information read from the relay history update information with the node ID in the relay history storage unit 44. Writing is performed (step S845). The relay history management unit 43 determines from the relay history information stored in the relay history storage unit 44 and the relay history information received from another node device 1 within a predetermined time from the node ID of the calling node and the current time. When the record in which the content search request information reception time indicating the time of the current record is specified and the number of the specified records is obtained as the number of relay processes, the number of relay processes is transferred to the abnormality detection unit 42 (step S850). ). Thereafter, processing similar to that of the first embodiment shown in FIG. 16 is performed. However, when the content search request information is transferred in step S365 after step S370, the transmission destination determination unit 20 determines the transmission destination selection condition stored in the transmission destination selection condition storage unit 21, the hash value of the content ID, and the like. Determines the range of the hash value of the node ID of the forwarding relay node, and is the largest hash included in the determined hash value range from among the node lists stored in the node storage unit 23 A value record is specified, and an IP address and a port number are read from the specified record.

  If it is determined in step S805 that the received information is notification information without fraud (step S805: notification information without fraud), the processing from step S345 in FIG. 16 is performed.

  If it is determined in step S805 that the received information is a black list (step S805: black list), processing similar to steps S390 to S395 in FIG. 15 is performed (steps S860 to S865).

  If it is determined in step S805 that the type of received information is content storage update information (step S805: content storage update information), the processing from step S400 in FIG. 17 is performed. However, when the content storage update information is transferred in step S365 after the process of step S410, the transmission destination determination unit 20 determines the transmission destination in the same manner as the transfer of the content search request information described above.

  If it is determined in step S805 that the type of the received information is relay history inquiry information (step S805: relay history inquiry information), the communication input unit 25 outputs the relay history inquiry information to the information reception unit 41. To do. The information receiving unit 41 outputs the relay history inquiry information to the relay history management unit 43, and the relay history management unit 43 associates the relay history information read from the relay history inquiry information with the node ID and relay history storage unit 44. (Step S870). The relay history management unit 43 of the node device 1 generates relay history inquiry information in which the relay history information read from the relay history storage unit 44 and its own node ID are set, and outputs them to the information sending unit 51 (step S875). ). The information sending unit 51 transfers the received relay history inquiry information to the communication output unit 24 (step S880), and the communication output unit 24 uses the relay history inquiry information as the IP address of the node device 1 that is the transmission source of the relay history inquiry information. And the port number as a destination.

[6. effect]
According to the embodiment described above, in a network in which content is distributedly managed using a P2P network, when searching for the location of the content, there is a relay node that exists on the path from the search request source node to the search target content management node. The search request relay history is managed for each source node. The relay node can detect a node device that is executing an abnormal process based on the relay history and output information of the detected node device. Then, in response to this output, whether or not the content is illegally used is confirmed. If the illegal use becomes clear, it is registered in the black list, and thereafter, the search request is not relayed. Thereby, since the acquisition of content by an unauthorized node device can be stopped, the number of content that is illegally used can be suppressed.

  In a P2P network composed of many node devices, a structural type in which content is distributed and managed using DHT is often applied without concentrating the load on the administrator. In the case of such a structure type P2P, each node device knows only the node devices in the vicinity of itself, and therefore, in order to download the content, the location of the content is always searched. Further, node devices that relay search requests are limited to nearby node devices. Therefore, by limiting the number of search relays in the node device in the vicinity of the originating node, that is, in the relay node, an unauthorized node device is detected before the content is actually downloaded, and this unauthorized node is detected. Prevent the device from acquiring content. Therefore, even if an unauthorized node device can illegally release DRM, the content itself cannot be acquired, and thus the content cannot be distributed illegally.

  The node device 1, the content distribution device 7, the node management device 8, and the license distribution device 9 described above have a computer system therein. The operation processes of the node device 1, the content distribution device 7, the node management device 8, and the license distribution device 9 are stored in a computer-readable recording medium in the form of a program, which is read by the computer system. By executing this, the above processing is performed. The computer system here includes a CPU, various memories, an OS, and hardware such as peripheral devices.

Further, the “computer system” includes a homepage providing environment (or display environment) if a WWW system is used.
The “computer-readable recording medium” refers to a portable medium such as a flexible disk, a magneto-optical disk, a ROM, and a CD-ROM, and a storage device such as a hard disk built in the computer system. Furthermore, the “computer-readable recording medium” dynamically holds a program for a short time like a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line. In this case, a volatile memory in a computer system serving as a server or a client in that case, and a program that holds a program for a certain period of time are also included. The program may be a program for realizing a part of the functions described above, and may be a program capable of realizing the functions described above in combination with a program already recorded in a computer system.

DESCRIPTION OF SYMBOLS 1 ... Node apparatus 11 ... Broadcast receiving part 12 ... Content management part 13 ... Content storage part 14 ... Download list management part 15 ... Download list storage part 16 ... Content guide management part 17 ... Content guide storage part 18 ... Function calculation part 19 ... Management node condition storage unit 20 ... transmission destination determination unit 21 ... transmission destination selection condition storage unit 22 ... node list management unit 23 ... node list storage unit 24 ... communication output unit 25 ... communication input unit 26 ... relay control unit 27 ... content management List management unit 28 ... content management list storage unit 29 ... input unit 30 ... display unit 31 ... search unit 41 ... information receiving unit 42 ... abnormality detection unit 43 ... relay history management unit 44 ... relay history storage unit 45 ... black list management unit 46 ... Blacklist storage unit 47 ... Management node determination unit 48 ... Content search answer information generation unit 49 ... Content Management list verification section 50 ... node inquiry information generating unit 51 ... information sending unit 7 ... content distribution device 8 ... node management apparatus 9 ... license distribution device

Claims (5)

The node device that constitutes a content distribution management system including a plurality of node devices and a network that connects the plurality of node devices, and that determines a node device that manages the location of content according to a predetermined rule,
A node list storage unit for storing a node list in which communication addresses of other node devices connected via the network are set;
A relay history storage unit that stores relay history information in which the identification information of the other node device is associated with the reception time of the content search request information;
A communication input unit that receives content search request information including identification information of content to be searched and identification information of the other node device from the other node device connected via the network;
The relay history information in which the time when the content search request information received by the communication input unit is received and the identification information of the other node device read from the content search request information is associated is written in the relay history storage unit. A relay history management unit that acquires the number of relay processes corresponding to the identification information of the other node device from the relay history information stored in the relay history storage unit,
An abnormality detection unit that determines whether the number of relay processes acquired by the relay history management unit exceeds a predetermined threshold;
An information sending unit that outputs the identification information of the other node device read from the content search request information when the abnormality detection unit determines that the number of relay processes exceeds a predetermined threshold;
Whether the node device is a node device that manages the location of the search target content based on the predetermined rule and the identification information of the search target content set in the content search request information A management node determination unit for determining
The abnormality detection unit determines that the number of relay processes does not exceed a predetermined threshold, and the management node determination unit determines that the node device is not a node device that manages the location of the content to be searched. A communication output unit that transmits the content search request information with the communication address read from the node list stored in the node list storage unit as a destination;
A node device comprising: When the abnormality detection unit receives information indicating that the other node device is invalid in response to the identification information of the other node device output by the information output unit, the abnormality detection unit displays the content search request information. Destroy,
When the communication output unit receives information indicating that there is no fraud corresponding to the identification information of the other node device output by the information output unit, the node stored in the node list storage unit The node device according to claim 1, wherein the content search request information is transmitted with the communication address read from the list as a destination. A blacklist storage unit for storing identification information of the unauthorized node device;
A black list management unit that receives the identification information of the unauthorized node device and writes the received identification information of the node device to the black list storage unit;
The abnormality detection unit discards the content search request information when the identification information of the other node device set in the content search request information is stored in the blacklist storage unit.
The node device according to claim 1 or 2, characterized in that The communication output unit transmits a relay history query with the communication address read from the node list stored in the node list storage unit as a destination,
The relay history management unit receives relay history information corresponding to the relay history inquiry transmitted by the communication output unit, and the received relay history information and the relay history information stored in the relay history storage unit To obtain the number of relay processes corresponding to the identification information of the other node device set in the content search request information,
The node device according to claim 1, wherein the node device is a node device. A computer used as the node device that constitutes a content distribution management system including a plurality of node devices and a network that connects the plurality of node devices, and that determines a node device that manages the location of content according to a predetermined rule,
A node list storage unit for storing a node list in which communication addresses of other node devices connected via the network are set;
A relay history storage unit that stores relay history information in which the identification information of the other node device is associated with the reception time of the content search request information;
A communication input unit for receiving content search request information including identification information of content to be searched and identification information of the other node device from the other node device connected via the network;
The relay history information in which the time when the content search request information received by the communication input unit is received and the identification information of the other node device read from the content search request information is associated is written in the relay history storage unit. A relay history management unit that acquires the number of relay processes corresponding to the identification information of the other node device from the relay history information stored in the relay history storage unit,
An abnormality detection unit for determining whether the number of relay processes acquired by the relay history management unit exceeds a predetermined threshold;
An information sending unit that outputs the identification information of the other node device read out from the content search request information when the abnormality detection unit determines that the number of relay processes exceeds a predetermined threshold;
Whether the node device is a node device that manages the location of the search target content based on the predetermined rule and the identification information of the search target content set in the content search request information A management node determination unit for determining
The abnormality detection unit determines that the number of relay processes does not exceed a predetermined threshold, and the management node determination unit determines that the node device is not a node device that manages the location of the content to be searched. A communication output unit that transmits the content search request information with the communication address read from the node list stored in the node list storage unit as a destination,
A computer program that functions as a computer program.

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