JP2012118710A - Node device, communication system, communication method and program for information processing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a communication system which is capable of effectively preventing pay content from being leaked over a P-2-P network where pay content and free content are distributed.SOLUTION: In a plurality of routers Rm included in a distribution system S in which content is distributed and stored in the routers Rm by an overlay network comprised of the routers Rm, the content includes pay content and free content and, from a user terminal Tm-n, a content request message is received which contains authentication information indicating that utilization of pay content is permitted, and content IDs identifying pay content in the overlay network. When authentication information is contained in the received content request message, pay content identified by a content ID contained in the content request message together with the authentication information is acquired and when authentication information is not contained in the received content request message, acquisition of pay content is restricted.

Description

  The present application belongs to a technical field of a node device, a communication system, a communication method, and an information processing device program. In the following description, the “node device” is appropriately referred to as a “node”.

  2. Description of the Related Art In recent years, techniques for distributing content such as movies and moving images via a peer-to-peer (P2P) type network have been developed. In the following description, a P2P type network is simply referred to as a “P2P network”. In a P2P network, content is distributed and stored in each node existing in the P2P network. Each node transmits and receives each other while sharing content between the nodes. The P2P network is disclosed in detail, for example, in Patent Document 1 below. On the other hand, paid content is also distributed in the P2P network. Paid content is content that is charged to the user for use. Paid content distribution may differ from free content distribution. For example, it is authentication of a user of pay content or prevention of leakage of the pay content itself. As a paid content distribution method corresponding to such a request, for example, there is a method disclosed in Patent Document 2 below. Patent Document 2 discloses that paid content is handled in a unified manner as content whose distribution targets are to be restricted.

JP 2006-197400 A JP 2005-339179 A

  In the P2P network, not only paid content but also free content is distributed. Distribution of free content is necessary in order to popularize content distribution using a P2P network. On the other hand, when these two contents are distributed through one P2P network, there is a problem that a general user may illegally access paid contents and use them without permission. Here, the general user is a user who is not allowed to use paid content. Therefore, when pay content and free content are distributed by one P2P network, there is a problem that it is necessary to prevent leakage of pay content to general users. On the other hand, in the invention described in Patent Document 2, only distribution of paid content is considered. In the invention described in Patent Document 2, problems such as unauthorized access that occurs in paid content when paying content and free content are distributed by one P2P network are not considered at all. Therefore, the invention described in Patent Document 2 cannot solve the above problem.

  Therefore, the present invention has been made in view of the above problems and problems, and an example of the purpose is to effectively leak paid contents to general users in a P2P network in which paid contents and free contents are distributed. It is an object of the present invention to provide a communication system that can be prevented, a node device included in the communication system, a communication method, and an information processing apparatus program.

  In order to solve the above-described problem, the invention according to claim 1 is configured such that content is distributed and stored in the plurality of node devices by an overlay network including a plurality of node devices capable of communicating via the network. In the node device included in the communication system, the content includes conditional content that imposes a predetermined condition on a user when using the content, and general content other than the conditional content. Receiving means such as a communication unit for receiving request information including authentication information indicating that use of the conditional content is permitted, and identification information for identifying the conditional content in the overlay network; Performs acquisition processing for acquiring the content from the overlay network When the authentication information is included in the request information received by the processing means such as a control unit and the reception means, the conditional information identified by the identification information included in the request information together with the authentication information. Executing the acquisition process for content, and controlling the processing means to limit the acquisition process for the conditional content when the authentication information is not included in the request information received by the receiving means Control means such as a control unit.

  According to the first aspect of the present invention, when authentication information and identification information are included in the received request information, an acquisition process for the conditional content identified by the identification information is executed. When authentication information is not included in the received request information, acquisition processing for conditional content is restricted. In a communication system in which conditional content and general content are distributed and stored, leakage of conditional content can be effectively prevented.

  3. The invention according to claim 2, wherein an encryption unit such as a processing unit that encrypts the conditional content acquired by the acquisition process, and a storage that stores the conditional content encrypted by the encryption unit. Storage means such as a storage unit, wherein the receiving means further receives importance information indicating the importance of security of the conditional content, and the encryption means receives the importance received by the receiving means. Based on the information, the conditional content having a higher importance level is encrypted with higher encryption strength.

  According to the second aspect of the present invention, conditional content with higher security importance is encrypted and stored with higher encryption strength. It is possible to effectively prevent leakage of conditional content according to the importance of security.

  The invention according to claim 3, wherein the storage unit includes a plurality of first storage areas corresponding to the importance level indicated by the importance level information, and the importance level information received by the reception unit is used as the condition information. Importance changing means such as a control unit that changes based on period information indicating a period from the date when the attached content becomes available to the present, and the conditional information in which the importance information is changed by the importance changing means The content storage area is changed from the first storage area corresponding to the importance information before the change by the importance changing means to the first storage area corresponding to the importance information after the change by the importance changing means. And a region changing means such as a control unit for changing to the above.

  According to the invention described in claim 3, the importance level information is changed based on a period from the date when the conditional content becomes available to the present, and the conditional content is stored based on the changed importance level information. The first storage area to be changed is changed. Since the first storage area corresponds to the importance level of security of conditional content, leakage of conditional content can be effectively prevented.

  5. The communication system according to claim 4, wherein the storage unit includes a plurality of first storage areas corresponding to the importance level indicated by the importance level information, and the communication system includes the content acquired by the acquisition process. The content transmission means such as a communication unit that transmits to the information processing apparatus to be transmitted and the importance information received by the reception means are changed based on transmission number information indicating the number of transmissions of the conditional content to the information processing apparatus The importance level changing means such as a control unit, and the storage area of the conditional content whose importance level information has been changed by the importance level changing means correspond to the importance level information before the change by the importance level changing means. Area changing means such as a control unit for changing from the first storage area to the first storage area corresponding to the importance information after being changed by the importance changing means. , Comprising a.

  According to the fourth aspect of the present invention, the first storage area that changes the importance level information based on the number of transmissions of conditional content to the information processing apparatus and stores the conditional content based on the changed importance level information. To change. Since the first storage area corresponds to the importance level of security of conditional content, leakage of conditional content can be effectively prevented.

  6. The invention according to claim 5, wherein the receiving means further receives user number information indicating the number of users who can use the conditional content, and stores the content acquired by the acquisition process. A storage means comprising: a first storage area for storing the conditional content; a second storage area for storing the general content; a storage means such as a storage unit; and the reception means received by the reception means Based on the number of users information, the capacity of the processing unit or the like that increases the capacity of the first storage area when the number of users increases and decreases the capacity of the first storage area when the number of users decreases. Changing means.

  According to the invention described in claim 5, when the number of users of conditional content increases, the capacity of the first storage area is increased, and when the number of users decreases, the capacity of the first storage area is decreased. Even when the number of users of conditional content increases, conditional content can be stored stably. Further, when the number of users of conditional content decreases, the capacity of the second storage area can be relatively increased.

  7. The invention according to claim 6, wherein the receiving means is catalog information for searching for the content stored in a distributed manner, and is attribute identification information for identifying the conditional content and the general content. Is further received from the overlay network, and the control unit identifies the conditional content and the general content based on the attribute identification information included in the catalog information received by the receiving unit. And configured to control the processing means.

  According to the sixth aspect of the invention, the processing unit is controlled by identifying the conditional content and the general content based on the attribute identification information for identifying the conditional content and the general content. It is possible to acquire catalog information, identify conditional content, and promptly execute an acquisition process.

  8. The invention according to claim 7, wherein the receiving unit identifies the conditional content and the general content from any of the node devices that manage index information indicating the location of the node device that stores the content. And receiving the attribute identification information to control the processing means by identifying the conditional content and the general content based on the attribute identification information received by the receiving means. Composed.

  According to the seventh aspect of the invention, the attribute identification information for identifying the conditional content and the general content is received from any of the node devices that manage the index information. Based on the received attribute identification information, the conditional content and the general content are identified to control the processing means. Since attribute identification information can always be acquired, conditional content can be quickly identified and acquisition processing can be executed.

  The invention according to claim 8, wherein the conditional content is any of first content that is charged for use or second content that is used by using value information indicating a predetermined value for use. It is configured to be either.

  According to the eighth aspect of the present invention, in the communication system in which either the first content or the second content as the conditional content and the general content are distributed and stored, the first content or the second content Can be effectively prevented.

  In order to solve the above-described problem, the invention according to claim 9 is configured such that content is distributed and stored in the plurality of node devices by an overlay network including a plurality of node devices capable of communicating via the network. In the communication system, the content includes conditional content for which a predetermined condition is imposed on a user when using the content, and general content other than the conditional content, and the conditional content When acquiring the conditional content from any of the node devices, the conditional content is identified in the overlay network, such as a control unit that acquires authentication information indicating that the use of the content is permitted A request including identification information and the authentication information acquired by the acquisition means An information processing device including a communication unit or the like that transmits information to any one of the node devices, and the node device receives the request information from the information processing device. When the authentication information is included in the request information received by the receiving unit such as a communication unit, the processing unit such as a control unit that performs an acquisition process for acquiring the content from the overlay network, and the receiving unit The acquisition process for the conditional content identified by the identification information included in the request information together with the authentication information is executed, and the authentication information is included in the request information received by the receiving unit. When there is no control, the control unit or the like that controls the processing means to limit the acquisition processing for the conditional content It includes a stage, a.

  In order to solve the above-described problem, the invention according to claim 10 is configured such that content is distributed and stored in the plurality of node devices by an overlay network including a plurality of node devices capable of communicating via the network. In the communication method executed in the communication system, the content includes conditional content that imposes a predetermined condition on the user when using the content, and general content other than the conditional content. And acquiring the authentication information indicating that the use of the conditional content is permitted, and when acquiring the conditional content from any of the node devices, the conditional content is stored in the overlay network. A request including identification information for identifying and the acquired authentication information A transmission step for transmitting information to any of the node devices, a reception step for receiving the request information, and when the authentication information is included in the received request information, it is included in the request information together with the authentication information. The acquisition process for acquiring the conditional content identified by the identification information that has been received from the overlay network is executed, and the acquisition process is performed when the authentication information is not included in the received request information. A controlling step of controlling.

  According to the invention described in claim 9 or claim 10, when the conditional content is acquired, the request information including the corresponding identification information and authentication information is transmitted. When authentication information is included in the transmitted request information, an acquisition process for conditional content identified by the identification information is executed. When authentication information is not included in the transmitted request information, acquisition processing for conditional content is restricted. In a communication system in which conditional content and general content are distributed and stored, leakage of conditional content can be effectively prevented.

  In order to solve the above-described problem, the invention according to claim 11 is such that content is distributed and stored in the plurality of node devices by an overlay network including a plurality of node devices capable of communicating via the network. In the communication system, the content includes conditional content for which a predetermined condition is imposed on a user when using the content, and general content other than the conditional content. An acquisition step of acquiring authentication information indicating that the use of the conditional content is permitted to a computer of the included information processing device, when acquiring the conditional content from any of the node devices, Identification information for identifying conditional content in the overlay network; and And transmitting the request information including the authentication information to any one of the node devices, and acquiring the conditional content identified by the identification information included in the transmitted request information from the overlay network The acquisition step is performed.

  According to the invention described in claim 11, when the conditional content is acquired, the computer is caused to function so as to acquire the corresponding authentication information. Request information including the identification information and the acquired authentication information is transmitted to the node device, and the computer is caused to function so as to acquire conditional content identified by the identification information included in the transmitted request information from the overlay network. In a communication system in which conditional content and general content are distributed and stored, leakage of conditional content can be effectively prevented.

  According to the present invention, when the received request information does not include authentication information, the acquisition process for conditional content is limited. In a communication system in which conditional content and general content are distributed and stored, leakage of conditional content can be effectively prevented.

It is a figure showing the outline composition of the distribution system of an embodiment. It is a block diagram which shows schematic structure, such as a router of embodiment. FIG. 2A is a block diagram illustrating a schematic configuration of a router and each server according to the embodiment. (B) is a block diagram showing a schematic configuration of a user terminal of the embodiment. It is a flowchart which shows the content input process in the center server of embodiment. It is a flowchart which shows the login process in the user terminal etc. of embodiment. (A) is a flowchart which shows the login process in a user terminal. (B) is a flowchart which shows the login process in a web server. It is a flowchart which shows the content acquisition process in the user terminal of embodiment. It is a flowchart which shows the content delivery process etc. in the router of embodiment.

  Next, modes for carrying out the present invention will be described based on the drawings. The embodiment described below is an embodiment in a case where the present invention is applied to a distribution system that distributes content such as a moving image from a node in a P2P network to a user terminal. In the following description, when pay content and free content are collectively referred to, they are simply referred to as “content”. In the following embodiments, paid content is subject to a predetermined condition of payment of a fee for a user who uses the content. This pay content corresponds to an example of “conditional content” and an example of “first content” in the present invention. Also, free content is not subject to these conditions for its use. This free content corresponds to an example of “general content” in the present invention.

(I) Embodiment First, an embodiment of the present invention will be described with reference to FIGS.

(A) Schematic Configuration of Distribution System With reference to FIG. 1, the schematic configuration of the distribution system of the embodiment will be described. FIG. 1 is a diagram illustrating a schematic configuration of the distribution system according to the embodiment. The delivery system S is a CDN (Contents Delivery Network system) to which DNS (Domain Name System) is applied. As shown in FIG. 1, in the distribution system S, a distribution center network NS and a plurality of base networks NLm (m is a natural number; the same applies hereinafter) are connected to the network NW. These network NW, distribution center network NS, and each base network NLm are real-world communication networks.

  The network NW is a network for interconnecting the distribution center network NS and each base network NLm. This network NW is, for example, a WAN (Wide Area Network). The network NW is constructed by, for example, IX (Internet eXchange), ISP (Internet Service Provider), DSL (Digital Subscriber Line) line provider equipment, FTTH (Fiber To The Home) line provider equipment, communication lines, and the like. . The network NW may be a network dedicated to the distribution system S.

  The distribution center network NS is a network constructed in the site of the distribution center C, for example. The distribution center network NS is constructed by, for example, a LAN (Local Area Network) or the like. A center server SD is connected to the distribution center network NS. The center server SD is a server that inputs content distributed to user terminals into the distribution system S. A plurality of distribution centers C may exist. A center server SD may be connected to each distribution center C network.

  Each base network NLm is a network constructed in the site of the base Pm. The base Pm is a base where an organization such as a company, a school, a hospital, a public organization, or a management body of a karaoke box operates. The base network NLm is constructed by, for example, a LAN. A plurality of user terminals Tm-n (n is a natural number; hereinafter the same) are connected to each base network NLm. The user terminal Tm-n is, for example, a personal computer. In FIG. 1, illustration of some base networks NLm and illustration of user terminals Tm-n connected to the base networks NLm are omitted. The user terminal Tm-n corresponds to an example of an “information processing apparatus” in the present invention.

  A web server SW and a DNS server SO are also connected to the network NW. The web server SW is a server for distributing, for example, various contents of a website operated by the organization having the base Pm described above to the user terminal Tm-n. In FIG. 1, only one web server SW is shown, but the web server SW is installed for each organization, for example. Each web server SW is individually assigned a domain name.

  The DNS server SO is a DNS server that resolves domain names. The DNS server SO receives an inquiry about an IP (Internet Protocol) address from the user terminal Tm-n. A unique domain name is assigned to the DNS server SO.

  A router Rm is regularly connected to the distribution center network NS and each base network NLm. The router Rm interconnects the distribution center network NS or the base network NLm and the network NW. The router Rm is, for example, a firewall having a router function, a broadband router, or the like. The router Rm corresponds to an example of a “node device” in the present invention.

(B) Outline Configuration of P2P Network In the distribution system S, a P2P network PW for distributing contents is constructed. As shown in FIG. 1, the P2P network PW is a logical overlay network constructed on the network NW. The P2P network PW is a network formed by participation of a plurality of routers Rm constituting the distribution system S. The router Rm participating in the P2P network PW is hereinafter referred to as a “node”. Further, as a node participating in the P2P network PW, a network device having a function of relaying information such as a proxy server, a load balancer, a web accelerator, etc. can be used in addition to the router Rm. Furthermore, for example, a server such as a cache server or an edge server or a personal computer may be used as the node. Here, “participation” in the P2P network PW means a state in which various messages can be transmitted / received to / from other nodes based on a routing table using DHT (Distributed Hash Table) disclosed in Patent Document 1, for example. To become. This routing table is hereinafter referred to as “DHT routing table”. In the distribution system S of the embodiment, only the router Rm participates in the P2P network PW at one site Pm. Each user terminal Tm-n at the site Pm does not participate in the P2P network PW.

  The P2P network PW is realized by a specific algorithm, for example, an algorithm using DHT. Each node connected to the P2P network PW is assigned a node ID, which is unique identification information consisting of a predetermined number of digits. In the P2P network PW shown in FIG. 1, the ID space of the node ID is shown as a ring shape. The position of each node shown in the ring-shaped ID space in FIG. 1 corresponds to each node ID.

  Each node holds a DHT routing table. The DHT routing table defines various message transfer destinations on the P2P network PW. Specifically, in the DHT routing table, a plurality of pieces of node information including node IDs, IP addresses, and port numbers of nodes that are moderately separated in the ID space are registered. Note that DHT routing using a DHT routing table is well known in Patent Document 1 and the like, and thus detailed description thereof is omitted.

  A node that distributes and stores content in the P2P network PW is hereinafter referred to as a “holding node”. Each content is assigned a content ID, which is identification information unique to each content. The content stored and stored in the holding node is content distributed to the user terminal Tm-n. The user terminal Tm-n of the embodiment acquires authentication information to be described later from the web server SW. The user terminal Tm-n acquires content from the holding node using the acquired authentication information.

  The location of the content distributed and stored in the plurality of holding nodes is stored as index information by the node managing the location of the content. A node that manages the location of content is hereinafter referred to as a “root node”. The index information includes a set of the node information of the holding node and the content ID of the content stored therein. Since the root node is known from Patent Document 1 and the like, detailed description thereof is omitted.

  When a certain node tries to acquire content, the node transmits a search message. A node from which content is to be acquired is hereinafter referred to as a “user node”. The search message includes the content ID of the content to be acquired, the IP address of the user node, and the like. The search message is a message for searching for holding nodes. The user node transmits a search message to other nodes according to the DHT routing table stored in the user node. As a result, the search message finally reaches the root node by DHT routing using the content ID as a key.

  The root node that has received the search message transmits index information corresponding to the content ID included therein to the user node. The user node transmits a content request message including the content ID to one of the holding nodes based on the IP address and port number included in the received index information. The holding node uploads content corresponding to the content ID included in the received content request message to the user node. Thus, the user node can acquire the content. As a result, this user node becomes a new holding node for holding the content.

(C) Content Distribution to User Terminal Next, the outline of content distribution to the user terminal Tm-n in the distribution system S will be described with reference to FIG.

  The content distributed to the user terminal Tm-n is first input from the center server SD to the distribution system S (FIG. 1 (1)). Here, “input” of content means that content is stored in at least one router Rm among a plurality of routers Rm and the content can be acquired from the P2P network PW. The importance information of the embodiment is added to the content input from the center server SD. Specifically, the importance level information is, for example, information having one of four values from “0” to “3”. Importance information has two uses. One application is an application indicating the degree of protection in the case where the content to which the importance information is added is protected from leakage. Another use is a use indicating whether the content to which the importance level information is added is paid content or free content. More specifically, when the importance level information value is “0”, the content to which the importance level information is added is free content. When the importance level information value is any one of “1” to “3”, the content to which the importance level information is added is paid content. Further, when the value of the importance information added is any one of “1” to “3”, the greater the value, the higher the degree of protection of the pay content to which the importance information having the value is added. high. In other words, the pay content to which the importance information having any value from “1” to “3” is added is the pay content with higher secrecy as the value increases. This “confidentiality” corresponds to the degree of importance of pay content security.

  Next, an outline of operation when content is downloaded in the user terminal Tm-n will be described. Specifically, in the following description, a case where content is downloaded at the user terminal T1-1 will be described as an example. When downloading content, the user terminal T1-1 first accesses the web server SW and acquires data for displaying a login page. The user terminal T1-1 displays a login page using the acquired data, and causes the user to perform a login process using the acquired data (FIG. 1 (2)). The web server SW stores a plurality of combinations of user IDs and passwords for performing login processing. When the login process using the user ID or the like is normally completed, the web server SW transmits authentication information corresponding to the user who operates the user terminal T1-1 to the user terminal T1-1 (FIG. 1 (3)). . This authentication information is information indicating that the user who performed the login process is a user who is permitted to view paid content. Reproduction and viewing of paid content corresponds to an example of “use of paid content” in the present invention. Specifically, for example, a cookie having a content corresponding to the user who performed the login process is used as the authentication information. In the following description, a user who is permitted to view paid content is referred to as a “paid user”. On the other hand, a user who is not permitted to view paid content and is only permitted to view free content is referred to as a “free user”. Further, when paying users and free users are collectively referred to, they are simply referred to as “users”.

  When the login process ends normally, the user terminal T1-1 displays a web page for allowing the user to select content. This web page for selection is hereinafter referred to as “user page”. User page data is also acquired from the web server SW. When the user of the user terminal T1-1 selects a link to the paid content on the user page, the user terminal T1-1 acquires a URL (Uniform Resource Locator) of the selected link. The user terminal T1-1 that has acquired the URL makes an inquiry about the IP address. Specifically, the user terminal T1-1 extracts the domain name indicating the server that requested the content from the acquired URL. Next, the user terminal T1-1 transmits a name resolution request including the extracted domain name to the DNS server SO (see FIG. 1 (4)). The DNS server SO holds in advance a database in which domain names and IP addresses of routers Rm are registered in association with each other. Then, based on the domain name included in the name resolution request from the user terminal T1-1, the DNS server SO acquires the IP address of any router Rm corresponding to the domain name from the database. At this time, the DNS server SO randomly selects and acquires an IP address from the database. Also, the DNS server SO may select and acquire an IP address having a value closest to the IP address of the user terminal T1-1 that has transmitted the name resolution request from the database. The DNS server SO returns the acquired IP address to the user terminal T1-1 (see FIG. 1 (5)). In the case illustrated in FIG. 1, it is assumed that the IP address returned to the user terminal T1-1 is the IP address of the router R2. Then, the user terminal T1-1 transmits a content request message to the router R2 based on the received IP address (see FIG. 1 (6)). When viewing paid content, the user terminal T1-1 transmits the authentication information acquired from the web server SW and the content ID of the paid content to be viewed included in the content request message. When viewing free content, the user terminal T1-1 transmits a content request message not including authentication information to the router R2 (see FIG. 1 (6)).

  On the other hand, catalog information is stored in each router Rm as a node participating in the P2P network PW. In the catalog information, attribute information such as a content ID and importance information about the content is described for each content. The catalog information is created by the center server SD or any router Rm node and distributed to all routers Rm. The router R2 that has received the content request message from the user terminal T1-1 first checks the catalog information stored in the router R2. Based on the contents of the confirmed catalog information, the router R2 determines whether the content requested by the content request message is paid content or free content. Specifically, the router R2 refers to the catalog information using the content ID of the content as a key. If the value of importance information described in the referenced catalog information is “0”, the router R2 determines that the requested content is free content. If the value of the importance level information is other than “0”, the router R2 determines that the requested content is paid content. When the requested content is paid content, the router R2 confirms whether or not the authentication information is included in the content request message received from the user terminal T1-1. If the authentication information is included, the router R2 searches and downloads the requested paid content in the P2P network PW. This search and download of paid content corresponds to an example of “acquisition processing” in the present invention. Thereafter, the router R2 uploads the downloaded paid content to the user terminal T1-1 (see FIG. 1 (7)). If the content request message does not include authentication information even though paid content is requested, the router R2 notifies the user terminal T1-1 that download is not possible. Next, the router R2 that has downloaded the paid content performs an encryption process on the paid content according to the importance information corresponding to the paid content. More specifically, paid content with a higher value of importance information is encrypted with higher encryption strength. The encrypted paid content is stored in the router R2. At this time, the router R2 becomes a holding node for the paid content. Through the series of processes described above, the user terminal T1-1 that has transmitted the name resolution request can acquire paid content corresponding to the name resolution request from the P2P network PW.

  When the content requested by the content request message is free content, the router R2 searches and downloads the free content in the P2P network PW. Search and download of this free content are performed by the same method as before. The downloaded free content is uploaded to the user terminal T1-1. The router R2 that downloaded the free content stores the free content without encryption.

(D) Configuration and Function of Router, etc. Next , the configuration and function of the router Rm and the like of the embodiment will be described with reference to FIG. The router Rm, the center server SD, and the web server SW of the embodiment basically have the same configuration. Therefore, in FIG. 2A below, the configuration of the router Rm will be described on behalf of these. FIG. 2A is a block diagram showing a schematic configuration of the router Rm. FIG. 2B is a block diagram showing a schematic configuration of the user terminal Tm-n.

(D-1) Configuration of Router As shown in FIG. 2A, the router Rm of the embodiment includes a storage unit 11, a control unit 12, and a communication unit 13. The storage unit 11, the control unit 12, and the communication unit 13 are interconnected via a bus 14 so that data can be exchanged. The control unit 12 is an example of “control means”, an example of “processing means”, an example of “capacity change means”, an example of “importance change means”, and an example of “area change means” in the present invention. Equivalent to. The storage unit 11 corresponds to an example of “save means” in the present invention. Further, the communication unit 13 corresponds to an example of “reception unit” and an example of “content transmission unit” in the present invention.

  In this configuration, the control unit 12 includes a CPU (Central Processing Unit) having an arithmetic function, a working RAM (Random Access Memory), a ROM (Read Only Memory) storing various data and a P2P program, and the like. The storage unit 11 includes an HD (hard disk) or the like for storing and storing various data and various programs. Further, the communication unit 13 controls communication of information with other routers Rm, user terminals Tm-n, and the like through the network NW, the base network NLm, and the like.

  Specifically, the storage unit 11 stores a DHT routing table, catalog information, index information, and the like. The storage unit 11 stores the downloaded content in association with the content ID. Further, the storage unit 11 stores a P2P program for transmitting / receiving various messages to / from other nodes based on the DHT routing table. The P2P program may be downloaded from a predetermined server, for example. The P2P program may be recorded on a recording medium such as a DVD (Digital Versatile Disc), for example, and read from the recording medium via a drive (not shown). The control unit 12 performs overall control of each unit of the router Rm of the embodiment by reading and executing a program including the P2P program stored in the storage unit 11 or the like by the CPU.

(D-2) Configuration of User Terminal Tm-n As shown in FIG. 2B, the user terminal Tm-n of the embodiment includes a control unit 21, a storage unit 22, a buffer memory 23, a communication unit 24, and a decoder unit. 25, an input unit 26, a video processing unit 27, a display unit 28, an audio processing unit 29, and a speaker 30. The control unit 21, the storage unit 22, the buffer memory 23, the communication unit 24, the decoder unit 25, and the input unit 26 are interconnected via a bus 31 so that data can be exchanged. The control unit 21 corresponds to an example of “acquiring means” in the present invention. The communication unit 24 corresponds to an example of a “transmission unit” in the present invention.

  In this configuration, the control unit 21 includes a CPU having an arithmetic function, a RAM that stores various data, and a ROM that stores programs including various data and P2P programs. The storage unit 22 includes an HD or the like for storing and storing various data and various programs. The buffer memory 23 temporarily stores content acquired via the communication unit 24. The decoder unit 25 decodes encoded video data, audio data, and the like included in the content. The video processing unit 27 performs a predetermined drawing process on the decoded video data or the like and outputs it as a video signal. The display unit 28 including a liquid crystal display displays an image corresponding to the video signal output from the image processing unit 27. The audio processing unit 29 D / A converts the decoded audio data into an analog audio signal, amplifies it, and outputs it to the speaker 30. The speaker 30 outputs the audio signal output from the sound processing unit 29 as a sound wave. The input unit 26 receives an instruction from the user and outputs an instruction signal corresponding to the instruction to the control unit 21. The input unit 26 is realized by, for example, a keyboard, a mouse, an operation panel, or the like. The communication unit 24 included in the user terminal Tm-n performs communication control of information between the router Rm and other user terminals Tm-n via the base network NLm.

  The storage unit 22 stores programs including the P2P program of the embodiment, files as contents, and the like. In the above configuration, the control unit 21 performs overall control of the entire user terminal Tm-n when the CPU reads and executes the P2P program stored in the storage unit 22 or the ROM.

(E) Processing of Distribution System Next, processing of the distribution system S in the embodiment will be described using FIG. 3 to FIG.

(E-1) Content Input Processing First, content input processing into the P2P network PW (see FIG. 1 (1)) will be specifically described with reference to FIG. FIG. 3 is a flowchart showing content input processing by the center server SD of the embodiment. The process shown in FIG. 3 is started when the P2P program of the center server SD is started, for example. First, the control unit 12 of the center server SD determines whether or not a new content input has been instructed by an operation or the like in an input unit (not shown in FIG. 2A) after completion of the predetermined initialization process (step S1). ). If the new content input is not instructed in the determination of step S1 (step S1; NO), the control unit 12 proceeds to the process of step S9 described later. When the input of new content is instructed in the determination of step S1 (step S1; YES), the control unit 12 generates a content ID corresponding to the new content (step S2). In step S <b> 2, the control unit 12 generates a new content ID using a method similar to the method described in Patent Document 1, for example. And the control part 12 adds the attribute information of the new content containing new content ID with respect to the catalog information used for the search of content in the P2P network PW (step S3). Next, the control unit 12 determines whether or not importance information corresponding to the new content has been input by an operation in the input unit or the like (step S4). If importance information is not input in the determination in step S4 (step S4; NO), the control unit 12 adds importance information having a value of “0” to the attribute information of the new content in the catalog information. (Step S5). On the other hand, when the importance information of any one of the values “1” to “3” is input in the determination of step S4 (step S4; YES), the control unit 12 sets the importance information having the input value to the step In the same manner as the process of S5, the content is added to the attribute information of the content (step S6). In the process of step S5 or S6, in the content attribute information, for example, each importance level information is added after the content ID added by the process of step S3. Next, the control unit 12 inputs the new content instructed to input by the process of step S1 into the P2P network PW (step S7). The process in step S7 is executed using the same charging method as in the prior art. Next, the control unit 12 distributes the catalog information to which the importance level information is added by the process of step S5 or S6 to the router Rm in the P2P network PW (step S8). The processing in step S8 is executed using a distribution method similar to the catalog information distribution method described in Patent Document 1, for example. Thereafter, the control unit 12 determines whether or not a request for ending the processing as the center server SD has been made by an operation or the like in the input unit or the like (step S9). When the termination request is not made in the determination of step S9 (step S9; NO), the control unit 12 proceeds to the process of step S1. When a termination request is made in the determination in step S9 (step S9; YES), the control unit 12 terminates the processing as the center server SD.

(E-2) Login Process Next, a login process (see FIGS. 1 (2) and (3)) executed in the user terminal Tm-n and the web server SW will be specifically described with reference to FIG. . FIG. 4A is a flowchart showing login processing in the user terminal Tm-n. FIG. 4B is a flowchart showing login processing in the web server SW. The process illustrated in FIG. 4A is started when the login page display operation is performed at the input unit 26 of the user terminal Tm-n, for example. The process shown in FIG. 4B is a process that is repeatedly executed in the web server SW, for example, at intervals set in advance.

  As shown in FIG. 4A, when a login page display operation is performed by the user in the login process, the control unit 21 of the user terminal Tm-n displays the login page using data from the web server SW. The information is displayed on the unit 28 (step S10). Next, the control unit 21 causes the user to input a user ID and password preset for the login page using the input unit 26 (step S11). And the control part 21 transmits the user ID and password input by the process of step S11 to web server SW (step S12). Here, when the user ID and password transmitted from the user terminal Tm-n are correct by the process of step S12, the web server SW transmits a cookie as the authentication information together with that fact. On the other hand, when the user ID and password transmitted from the user terminal Tm-n are not correct, an error message to that effect is transmitted from the web server SW as will be described later. Therefore, the control unit 21 of the user terminal Tm-n that has transmitted the user ID or the like determines whether or not a cookie is included in the reply from the web server SW corresponding to the transmitted user ID or the like (step S13). . When the determination in step S13 includes a cookie (step S13; YES), the control unit 21 receives the cookie (step S14). Thereafter, the control unit 21 causes the display unit 28 to display the user page used for content selection or the like using data transmitted from the web server SW following the cookie (step S15). Thereafter, the control unit 21 proceeds to a content acquisition process which will be described later with reference to FIG. On the other hand, when an error message instead of a cookie is returned in the determination in step S13 (step S13; NO), the control unit 21 executes error processing using the error message (step S16). Specifically, as the process of step S16, the control unit 21 causes the display unit 28 to display an error message indicating that login has failed, for example. Thereafter, the control unit 21 determines whether or not a request for ending the login process as the user terminal Tm-n has been made by an operation or the like in the input unit (step S17). When the termination request is not made in the determination of step S17 (step S17; NO), the control unit 21 proceeds to the process of step S11 and causes the user to input the user ID and password again. When the termination request is made in the determination in step S17 (step S17; YES), the control unit 21 terminates the login process as the user terminal Tm-n. The log-in process as the user terminal Tm-n is executed by the processes in steps S10 to S17 described above. The contents of the cookie transmitted from the web server SW include, for example, data indicating the name of the cookie, value data indicating that the user is a paid user, site path data for displaying the user page, arbitrary Flag data, time data indicating the expiration date of the cookie, data indicating the creation time of the cookie, and the like are included.

  On the other hand, as shown in FIG. 4B, in the login process, the control unit 12 of the web server SW monitors the presence / absence of access from any of the user terminals Tm-n (step S20). Specifically in this step S20, the control part 12 monitors the presence or absence of transmission, such as user ID from the user terminal Tm-n (refer Fig.4 (a) step S12). When there is no access in the monitoring in step S20 (step S20; NO), the control unit 12 proceeds to an operation in step S28 described later. When there is an access in the monitoring in step S20 (step S20; YES), the control unit 12 receives the transmitted user ID and the like (step S21). Next, the control unit 12 determines whether or not the combination of the received user ID and password is correct (step S22). Specifically, as a determination in step S22, the control unit 12 determines whether or not the combination of the received user ID and password matches any one of the combinations of user IDs and passwords stored in the storage unit 11. judge. Specifically, the control unit 12 determines that the received user ID or the like is correct when the combination of the received user ID and password matches any of the stored combinations of the user ID and password. That is, the control unit 12 determines that the user of the user terminal Tm-n that has transmitted the user ID or the like is a regular paying user. On the other hand, when the combination of the received user ID and password does not match any of the stored combinations of the user ID and password, the control unit 12 determines that the received user ID or the like is not correct. That is, the control unit 12 determines that the user of the user terminal Tm-n that has transmitted the user ID or the like is not a regular paying user. If the combination of the received user ID and the like is not correct in the determination of step S22 (step S22; NO), the control unit 12 transmits the error message to the user terminal Tm-n that has transmitted the user ID and the like. (Step S23; see FIG. 4 (a) Steps S13 and S16). Thereafter, the control unit 12 proceeds to an operation of step S28 described later. On the other hand, if it is determined in step S22 that the combination of the received user ID and the like is correct (step S22; YES), the control unit 12 generates a cookie corresponding to the user ID and the like (step S25). Next, the control unit 12 transmits the generated cookie to the user terminal Tm-n that has transmitted the user ID and the like (step S26; see steps S13 and S14 in FIG. 4A). Next, the control unit 12 transmits the user page display data to the user terminal Tm-n that has transmitted the user ID and the like (step S27; see step S15 in FIG. 4A). The login process as the web server SW is executed by the processes in steps S20 to S27. Thereafter, the control unit 12 determines whether or not a request for ending the login process as the web server SW has been made by an operation in the input unit or the like (step S28). When the termination request is not made in the determination of step S28 (step S28; NO), the control unit 12 proceeds to the process of step S20. If a termination request is made in the determination in step S28 (step S28; YES), the control unit 12 terminates the login process as the web server SW.

(E-3) Content Acquisition Processing Next, content acquisition processing and the like (see FIGS. 1 (4) to (7)) executed in the user terminal Tm-n and the router Rm, respectively, will be described in detail with reference to FIGS. Will be described. FIG. 5 is a flowchart showing content acquisition processing in the user terminal Tm-n. FIG. 6 is a flowchart showing content distribution processing and the like in the router Rm. The process shown in FIG. 5 is continuously executed, for example, in the user terminal Tm-n after the login process shown in FIG. Further, the process illustrated in FIG. 6 is a process that is repeatedly executed in the router Rm, for example, at predetermined intervals.

  When the login process shown in FIG. 4A ends normally, a user page for content selection is displayed on the display unit 28 of the user terminal Tm-n (see step S15 in FIG. 4A). In the user page in this case, for example, thumbnail images representing the contents of selectable contents are displayed for each selectable content. For example, a pair of an IP address of the DNS server SO and a content ID of content having contents represented by the thumbnail image is associated with the thumbnail image. In this state, the control unit 21 of the user terminal Tm-n monitors whether any of the displayed thumbnail images is selected by operating the input unit 26 (step S30). ). When no thumbnail image is selected in the monitoring in step S30 (step S30; NO), the control unit 21 proceeds to the process in step S39 described later. On the other hand, when any thumbnail image is selected in the monitoring in step S30 (step S30; YES), the control unit 21 inquires about the acquisition destination of the content corresponding to the selected thumbnail image (step S31). In the process of step S31, the control unit 21 assigns the IP address of the content holding node to the DNS server SO associated with the selected thumbnail image, for example, by the method illustrated in FIGS. 1 (4) and (5). Inquire. The control unit 21 that has inquired about the content acquisition destination determines whether or not there is a reply of the IP address from the DNS server SO (step S32; see FIG. 1 (5)). When there is no reply of the IP address in the determination of step S32 (step S32; NO), the control unit 21 continues to wait for the reply. On the other hand, when there is a reply of the IP address in the determination of step S32 (step S32; YES), the control unit 21 generates a content request message using the returned IP address (step S33). This content request message includes, for example, a character string indicating that it is a content request at the top thereof. Further, following this character string, the cookie acquired in the login process and the content ID of the content to be requested are included. This content ID is the content ID associated with the thumbnail image selected in the process of step S30. Note that when the user of the user terminal Tm-n is a free user, the login process described with reference to FIG. 4 is not executed, and thus the content request message does not include a cookie. Thereafter, the control unit 21 transmits the generated content request message to the router Rm having the IP address returned by the processing of steps S31 and S32 (step S34, see FIG. 1 (6)). The control unit 21 that has transmitted the content request message determines whether or not there is a reply from the destination router Rm (step S35). This reply includes content to be downloaded at the user terminal Tm-n. For example, when an unauthorized free user executes the content acquisition process shown in FIG. 5, the content request message does not include a cookie. When such a content request message is transmitted from the user terminal Tm-n, the router Rm replies with download impossible information as will be described later. If there is no reply from the router Rm in the determination in step S35 (step S35; NO), the control unit 21 continues to wait for the reply. On the other hand, when the reply including the content is received from the router Rm in the determination in step S35 (step S35; YES), the control unit 21 downloads the content (see FIG. 1 (7)). Thereafter, the control unit 21 determines whether or not all of the content download has been completed (step S36). In the determination in step S36, the control unit 21 determines whether or not the download disable information is included in the reply from the router Rm. If the reply from the router Rm includes the download impossible information in the determination in step S36 (step S36; NO), the control unit 21 performs a download failure process for displaying the fact on the display unit 26, for example (step S38). ). Thereafter, the control unit 21 proceeds to the process of step S39 described later. On the other hand, when the download of the necessary content is completed in the determination of step S36 (step S36; YES), the control unit 21 reproduces the downloaded content (step S37). Thereby, the user of the user terminal Tm-n views the content. Thereafter, the control unit 21 determines whether or not a request for ending the content acquisition process as the user terminal Tm-n has been made by an operation or the like at the input unit 26 (step S39). When the termination request is not made in the determination of step S39 (step S39; NO), the control unit 21 proceeds to the process of step S30. When a termination request is made in the determination in step S39 (step S39; YES), the control unit 21 terminates the content acquisition process as the user terminal Tm-n.

  Next, content acquisition processing executed in the router Rm will be described with reference to FIG. In this case, the router Rm is a user node. As shown in FIG. 6, as content acquisition processing, the control unit 12 of the router Rm monitors whether or not a content request message has been received from any user terminal Tm-n (step S40). When the content request message is not received in the monitoring in step S40 (step S40; NO), the control unit 12 proceeds to an operation in step S55 described later. On the other hand, when the content request message is received in the monitoring in step S40 (step S40; YES), the control unit 12 searches the catalog information using the content ID included in the received content request message (step S41). . Next, the control unit 12 determines whether or not the value of the importance level information of the content identified by the content ID in the retrieved catalog information is “0” (step S42). That is, the control unit 12 determines whether the requested content is paid content or free content. When the value of the importance information of the content is “0” in the determination in step S42 (step S42; YES), the control unit 12 proceeds to the process in step S44 described later. On the other hand, when the value of the importance level information of the content is not “0” in the determination in step S42 (step S42; NO), the control unit 12 next determines whether or not a cookie is included in the received content request message. Determination is made (step S43). If the cookie is not included in the determination in step S43 (step S43; NO), the free user is requested to download the paid content. Therefore, the control unit 12 transmits download disable information to the user terminal Tm-n that has transmitted the content request message (step S56). Thereafter, the control unit 12 proceeds to a process of step S55 described later. On the other hand, when a cookie is included in the determination in step S43 (step S43; YES), the control unit 12 next searches for content in the P2P network PW using the content ID included in the content request message ( Step S44). The processing in step S44 is executed using a search method similar to the content search method described in Patent Document 1, for example. Next, the control unit 12 downloads the searched content from the other router Rm that is the holding node (step S45). Thereafter, the control unit 21 determines whether or not all of the content download has been completed (step S46). If the content download is not completed in the determination in step S46 (step S46; NO), the control unit 12 continues the download until the download is completed. On the other hand, when all the downloads are completed in the determination of step S46 (step S46; YES), the control unit 12 next refers to the catalog information to determine whether the value of the importance information of the downloaded content is “0”. (Step S47). That is, the control unit 12 identifies paid content and free content based on importance information in the catalog information. When the value of the importance level information is “0” in the determination in step S47 (step S47; YES), the content is free content. Therefore, the control unit 12 stores the downloaded content as it is in the storage unit 11 (step S53). Then, the control unit 12 uploads the downloaded content to the user terminal Tm-n that has transmitted the content request message (step S54; see FIG. 1 (7)). Thereafter, the control unit 12 determines whether or not a request for ending the content acquisition process as the router Rm has been made by an operation or the like at the input unit of the router Rm (not shown) (step S55). When the termination request is not made in the determination of step S55 (step S55; NO), the control unit 12 proceeds to the process of step S40. When a termination request is made in the determination in step S55 (step S55; YES), the control unit 12 terminates the content acquisition process as the router Rm. On the other hand, if the value of the importance level information is not “0” in the determination in step S47 (step S47; NO), the content is a pay content corresponding to the importance level information having any value. Therefore, the control unit 12 first determines whether or not the value of the importance information is “1” (step S48). When the value of the importance level information is “1” in the determination in step S48 (step S48; YES), the control unit 12 performs an encryption process with a key length of, for example, 128 bits on the downloaded content (step S49). ). Thereafter, the control unit 12 stores the content encrypted with the 128-bit key in the storage unit 11 together with the key (step S53). Thereafter, the control unit 12 proceeds to the processing after step S54. On the other hand, when the importance level information value is not “1” in the determination in step S48 (step S48; NO), the control unit 12 next determines whether the importance level information value is “2” (step S48). Step S50). When the value of the importance level information is “2” in the determination in step S50 (step S50; YES), the control unit 12 performs an encryption process with a key length of, for example, 196 bits on the downloaded content (step S51). ). Thereafter, the control unit 12 stores the content encrypted with the 196-bit key in the storage unit 11 together with the key (step S53). Thereafter, the control unit 12 proceeds to the processing after step S54. On the other hand, if the importance information value is not “2” in the determination in step S50 (step S50; NO), the importance information value of the content is “3”. Therefore, the control unit 12 performs an encryption process with a key length of, for example, 256 bits on the downloaded content (step S52). Thereafter, the control unit 12 stores the content encrypted with the 256-bit key in the storage unit 11 together with the key (step S53). That is, based on the value of the importance level information, the control unit 12 encrypts the paid content with higher security importance level with higher encryption strength. Thereafter, the control unit 12 proceeds to the processing after step S54. Note that the paid content uploaded by the process of step S54 executed through the encryption process of step S49, S51 or S52 is not encrypted.

  As described above, according to the processing of the distribution system S of the embodiment, as exemplified in steps S42 to S45 in FIG. 6, the content request message received by the router Rm includes the cookie and the content ID as authentication information. If it is, the paid content acquisition process is executed. Also, as exemplified in steps S42, S43, and S56 in FIG. 6, when the received content request message does not include a cookie, the acquisition processing for the paid content is restricted. In the distribution system S in which paid content and free content are distributed and stored, leakage of paid content can be effectively prevented.

  Furthermore, as illustrated in steps S48 to S53 in FIG. 6, the paid content having a higher security importance level and a higher importance level information value is encrypted with higher encryption strength and stored. Leakage of paid content can be effectively prevented according to the importance of security.

  Further, as illustrated in steps S47, S53, and S54 in FIG. 6, the paid content and the free content are identified based on the importance information for identifying the paid content and the free content, and the acquisition is controlled. It is possible to acquire catalog information, identify paid content, and quickly execute the acquisition process.

(II) Modified Embodiment Next, a modified embodiment of the present invention will be described. In the description of the following modified embodiments, the member numbers and the like used for the description of the distribution system S of the embodiment will be described.

(A) First Modification First, a first modification will be described. In the router Rm of the embodiment, the key length is changed according to the value of the importance level information of the downloaded paid content, and the encrypted content is stored. On the other hand, the storage unit 11 of the router Rm can be divided in advance into a plurality of storage areas, and each storage area can be selectively used according to the value of importance information. This storage area corresponds to an example of the “first storage area” in the present invention. More specifically, four storage areas are provided in the storage unit 11 in correspondence with the values of the importance information. Then, the control unit 12 of the router Rm stores the free content in the storage area corresponding to the importance level information of the value “0” without taking any leakage prevention measures. On the other hand, the control unit 12 sets a password for accessing the storage area itself in each storage area corresponding to the importance information of the value “1” to the value “3”. Then, similarly to the embodiment, the control unit 12 stores the pay content encrypted with the key length corresponding to the value of the importance information in the storage area corresponding to the importance information of the value. At this time, the control unit 12 is configured to dynamically change the value of the importance information according to a predetermined rule, and to change the storage area of the paid content based on the importance information of the value after the change. May be. As an example of the predetermined rule, the control unit 12 changes the value of the importance level information based on period information indicating a period from the date when paid content becomes available to the present, for example. Specifically, the control unit 12 decreases the value of the importance level information by “1” every time one month elapses from the date when the paid content becomes available. This example is a change in the value of importance level information based on the fact that the importance level of security decreases as the period during which paid content is generally available is longer. As another example of the predetermined rule, the control unit 12 changes the value of the importance level information based on the upload number information indicating the frequency of uploading the paid content to the user terminal Tm-n. This upload number information corresponds to an example of “transmission number information” in the present invention. Specifically, the control unit 12 decreases the value of the importance level information by “1” if five days or more have elapsed since the previous upload of the paid content as viewed from the current time. On the other hand, if the interval between the current time and the previous upload is within two days, the control unit 12 conversely increases the value of the importance level information by “1”. In other cases, the control unit 12 does not change the value of the importance level information. This example is a change in the value of importance information based on the fact that paid content with a low upload frequency can generally be regarded as not popular, so that the importance of security needs to be lowered to promote viewing. Based on the importance information of the value after the change in accordance with such a rule, the control unit 12 changes the storage area for the pay content. According to the first modification, the value of the importance information corresponding to the importance of the security of the paid content and the storage area thereof are changed, so that leakage of the paid content can be effectively prevented.

(B) Second Modification Next, a second modification will be described. The router Rm of the embodiment includes a storage unit 11 that stores content. Therefore, the storage unit 11 is divided into a pay content storage area and a free content storage area. This pay content storage area corresponds to another example of the “first storage area” in the present invention. The free content storage area corresponds to an example of the “second storage area” in the present invention. The capacity of the pay content storage area can be increased or decreased relative to the capacity of the free content storage area in accordance with the increase or decrease in the number of pay users. Specifically, for example, the number of users indicating the number of paying users is stored in the center server SD while being updated as needed. And the control part 12 of the center server SD delivers the number-of-users information to each router Rm regularly, for example. At this time, the number-of-users information may be periodically requested from each router Rm to the center server SD. Then, the control unit 12 of each router Rm increases the capacity of the pay content storage area in the storage unit 11 in the storage area of the free content when the number of pay users has increased by 1.2 times, for example, compared to the previous confirmation. For example, increase by 5% relative to the capacity. When the number of paying users is reduced by, for example, 0.8 times compared to the previous confirmation, the control unit 12 sets the capacity of the pay content storage area in the storage unit 11 to the capacity of the free content storage area. For example, decrease by 5%. That is, based on the number of users information, the control unit 12 increases the capacity of the pay content storage area when the number of pay users increases, and decreases the capacity of the pay content storage area when the number of pay users decreases. According to the second modification, paid content can be stably stored even when the number of paying users increases. When the number of paying users decreases, the capacity of the free content storage area can be relatively increased.

(C) Third Modification Next, a third modification will be described. In the distribution system S of the embodiment, the importance level information of each content is distributed to each router Rm as part of the catalog information. On the other hand, it is also possible to store the importance information of the content in the root node that manages the content so that it can be confirmed from another router Rm. In this case, the importance level information can always be confirmed in each router Rm, and the content can be downloaded quickly. In addition, there is an effect that the capacity of the catalog information stored in each router Rm can be reduced and the storage unit 11 can be used effectively.

(D) Fourth Modification Next, a fourth modification will be described. In the distribution system S of the embodiment, the user terminal Tm-n where the content is viewed has not participated in the P2P network PW. On the other hand, the user terminal Tm-n itself can be configured to participate in the P2P network PW as one node. In this case, the control unit 21 of the user terminal Tm-n acquires a cookie from the web server SW by the same login process as in the embodiment. Then, the control unit 21 of the user terminal Tm-n refers to the catalog information stored in the storage unit 22 and confirms the value of the importance level information of the content to be acquired. When pay content is to be acquired and the cookie has been acquired normally, the control unit 21 of the user terminal Tm-n searches for and acquires the pay content in the P2P network PW. The search and acquisition at this time are performed by a method similar to the conventional method described in Patent Document 1, for example. On the other hand, in the case where paid content is to be acquired but the cookie has not been acquired normally, the control unit 21 does not search and acquire the paid content by the user terminal Tm-n. When the free content is to be acquired, the control unit 21 searches for and acquires the free content in the P2P network PW by a method similar to the conventional method described in Patent Document 1, for example. According to the fourth modification, even when the user terminal Tm-n participates in the P2P network PW as a node, the same effect as the distribution system S of the embodiment can be obtained.

(E) Other Variations In the above embodiment and each variation, the content is an example of “conditional content” in the present invention, paid content as an example of “first content”, and “general content” in the present invention. As an example, the case of being classified into free content has been described. In addition to this, when viewing the content, the present invention is used when the content is classified into content that requires the use of points given to those who use the content and content that can be viewed without using points. Can also be applied. Here, a part of the points that have been given to the person is consumed by the above use. In addition, this point may be given when the person uses another service. At this time, the content that requires the use of points for viewing corresponds to another example of “conditional content” or one example of “second content” in the present invention. Further, content that can be viewed without using points corresponds to another example of “general content” in the present invention. Furthermore, the points correspond to an example of “value information” in the present invention. In addition to the above points, the value information in this case includes actual articles other than the points, clothes worn by so-called avatars used in the so-called Internet community, parts thereof, or predetermined items. It's okay.

  In addition, the present invention can be applied to a case where the content is divided into special content that can be viewed only by users whose usage period of the distribution system S is longer than a predetermined period and general content other than that. In this case, the special content corresponds to yet another example of “conditional content” in the present invention. Even when the present invention is applied when content is divided in this way, the same effects as the distribution system S of the embodiment can be obtained.

  Further, in the above embodiment and each modified embodiment, the P2P network using DHT is applied to the overlay network, but the present invention is not limited to this. For example, a system using another P2P network or an overlay network may be applied. An example of a P2P network that does not use DHT is a hybrid P2P network.

11, 22 Storage unit 12, 21 Control unit 13, 24 Communication unit 26 Input unit 28 Display unit Rm Router SO DNS server SW Web server SD center server NLm Base network NW network PW P2P network S Distribution system Tm-n User terminal

Claims (11)

In the node device included in the communication system in which content is distributed and stored in the plurality of node devices by an overlay network configured by a plurality of node devices capable of communicating via the network,
The content includes conditional content for which a predetermined condition is imposed on the user when using the content, and general content other than the conditional content,
Receiving means for receiving request information including authentication information indicating that use of the conditional content is permitted, and identification information for identifying the conditional content in the overlay network;
Processing means for performing an acquisition process for acquiring the content from the overlay network;
When the authentication information is included in the request information received by the receiving unit, the acquisition process for the conditional content identified by the identification information included in the request information together with the authentication information is executed. And control means for controlling the processing means so as to limit the acquisition processing for the conditional content when the authentication information is not included in the request information received by the receiving means;
A node device comprising: Encryption means for encrypting the conditional content acquired by the acquisition process;
Storage means for storing the conditional content encrypted by the encryption means;
Further comprising
The receiving means further receives importance information indicating the importance of security of the conditional content;
2. The node according to claim 1, wherein the encryption unit encrypts the conditional content having a higher importance level with a higher encryption strength based on the importance level information received by the reception unit. apparatus. The storage means includes a plurality of first storage areas corresponding to the importance degree indicated by the importance information,
Importance changing means for changing the importance information received by the receiving means based on period information indicating a period from a date when the conditional content becomes available to the present;
The storage area of the conditional content whose importance information has been changed by the importance changing means is changed from the first storage area corresponding to the importance information before the change by the importance changing means to the importance change. Area changing means for changing to the first storage area corresponding to the importance information after the change by means;
The node device according to claim 2, further comprising: The storage means includes a plurality of first storage areas corresponding to the importance degree indicated by the importance information,
Content transmitting means for transmitting the content acquired by the acquisition process to an information processing device included in the communication system;
Importance changing means for changing the importance information received by the receiving means based on transmission number information indicating the number of transmissions of the conditional content to the information processing device;
The storage area of the conditional content whose importance information has been changed by the importance changing means is changed from the first storage area corresponding to the importance information before the change by the importance changing means to the importance change. Area changing means for changing to the first storage area corresponding to the importance information after the change by means;
The node device according to claim 2, further comprising: The receiving means further receives user number information indicating the number of users who can use the conditional content,
Storage means for storing the content acquired by the acquisition process, comprising: a first storage area for storing the conditional content; and a second storage area for storing the general content;
Based on the number-of-users information received by the receiving means, the capacity of the first storage area is increased when the number of users is increased, and the capacity of the first storage area is decreased when the number of users is decreased. Capacity changing means for reducing capacity,
The node device according to any one of claims 1 to 4, further comprising: The receiving means is catalog information for searching for the content stored in a distributed manner, and includes catalog information including attribute identification information for identifying the conditional content and the general content from the overlay network. Receive further,
The control means controls the processing means by identifying the conditional content and the general content based on the attribute identification information included in the catalog information received by the receiving means. The node device according to any one of claims 1 to 5. The receiving means further receives attribute identification information for identifying the conditional content and the general content from any of the node devices that manage index information indicating the location of the node device that stores the content,
The control unit controls the processing unit by identifying the conditional content and the general content based on the attribute identification information received by the receiving unit. The node device according to any one of 5.   The conditional content is any one of first content charged for use or second content used by using value information indicating a predetermined value for use. The node device according to any one of claims 1 to 7. In a communication system in which content is distributed and stored in the plurality of node devices by an overlay network configured by a plurality of node devices capable of communicating via the network,
The content includes conditional content for which a predetermined condition is imposed on the user when using the content, and general content other than the conditional content,
Obtaining means for obtaining authentication information indicating that use of the conditional content is permitted;
When acquiring the conditional content from any of the node devices, any of request information including identification information for identifying the conditional content in the overlay network and the authentication information acquired by the acquisition unit Transmitting means for transmitting to the node device;
An information processing apparatus comprising the communication system is included in the communication system,
The node device is
Receiving means for receiving the request information from the information processing apparatus;
Processing means for performing an acquisition process for acquiring the content from the overlay network;
When the authentication information is included in the request information received by the receiving unit, the acquisition process for the conditional content identified by the identification information included in the request information together with the authentication information is executed. And control means for controlling the processing means so as to limit the acquisition processing for the conditional content when the authentication information is not included in the request information received by the receiving means;
A communication system comprising: In a communication method executed in a communication system in which content is distributed and stored in the plurality of node devices by an overlay network configured by a plurality of node devices capable of communicating via the network,
The content includes conditional content for which a predetermined condition is imposed on the user when using the content, and general content other than the conditional content,
An acquisition step of acquiring authentication information indicating that use of the conditional content is permitted;
When acquiring the conditional content from any of the node devices, request information including identification information for identifying the conditional content in the overlay network and the acquired authentication information is provided to any of the node devices. Sending process to send to,
Receiving the request information; and
An acquisition process for acquiring the conditional content identified by the identification information included in the request information together with the authentication information from the overlay network when the received request information includes the authentication information And when the received request information does not include the authentication information, a control step for controlling the acquisition process,
A communication method comprising: A communication system in which content is distributed and stored in the plurality of node devices by an overlay network composed of a plurality of node devices that can communicate via a network, and the content is used when the content is used A computer of an information processing device included in a communication system that includes conditional content on which a predetermined condition is imposed on a person and general content other than the conditional content,
An acquisition step of acquiring authentication information indicating that use of the conditional content is permitted;
When acquiring the conditional content from any of the node devices, request information including identification information for identifying the conditional content in the overlay network and the acquired authentication information is provided to any of the node devices. Sending step to send to, and
Obtaining the conditional content identified by the identification information included in the transmitted request information from the overlay network;
A program for an information processing device that causes a program to be executed.

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