JP4360883B2 - Information search method, information search device, and information search program - Google Patents

Description

  The present invention relates to an information search method, an information search device, and an information search program for searching for information shared on a peer-to-peer (P2P) network. In particular, information disclosed in a large number of devices is collectively displayed. The present invention relates to an information search method, an information search device, and an information search program for searching.

  With the development of information communication technology in recent years, various services are provided via networks. At this time, there are various forms of services provided, and in order to provide a new form of service, it may be necessary to add or change components on the network according to the service.

  Also, in a wide area network such as the Internet, there is a risk that a transmitted packet may reach a malicious third party. Even in such a case, it is necessary to maintain the confidentiality of the packet contents and the anonymity of the communication partner.

  Thus, with the spread of service provision via the network, it is desired that the network configuration can be easily changed and that anonymity regarding communication via the network is maintained.

-Ease of change of network configuration There is a P2P network as a network whose configuration can be easily changed. A P2P network is a network in which nodes (Peer) having equal functions communicate directly with each other without a broker (no centralized management unit).

  The P2P network has a feature that the configuration can be dynamically changed. That is, in the P2P network, the participation of the node in the network and the exit from the network are arbitrary. Therefore, when performing communication on the P2P network, the packet is transferred to the transmission destination node while performing P2P communication between the nodes participating at that time. If a P2P network is used, information can be shared between computers without going through a specific server.

・ Information leakage prevention Various technologies are being considered to protect the anonymity of data senders and receivers on the Internet. In order to protect the anonymity of data transmission / reception, it is necessary to encrypt all data communication and not to leak the packet transmission path.

  In order to prevent the leakage of the packet transmission path, it is necessary to shut out the leakage of information such as the reception source and transfer destination of the packet during communication by utilizing a plurality of relay points (routers). As such a transmission path leakage prevention technique, a technique named “onion routing” is known (see, for example, Patent Document 1).

  In the method of onion routing, routing is performed by a robust and fixed router called an onion router. In the transmission terminal, a transmission path to the transmission partner is determined in advance, and information on the transmission path of the packet is encrypted using the public key of each onion router that relays the packet.

  The onion router that receives the packet decrypts the information on the transmission path with its own secret key. This decryption determines the next transfer destination of the packet, and the onion router transfers the packet to the next node (onion router or receiving terminal). In this manner, each onion router can maintain a concealed state except for the next transfer destination, and therefore cannot identify the final receiving terminal information. Further, when sending a packet in the onion router, it is possible to prevent the transmission source from leaking by not adding to the packet information related to the transmission path up to that point.

As described above, in onion routing, the route information to the destination in the data packet is multiplexed and stored, so that part of the route information is provided to each node that performs routing and those who perform skimming on the network. I can only refer to it.
US Pat. No. 6,266,704

  However, in the information sharing technique in the P2P network described above, the efficiency of search on the P2P network has not been considered. As a result, information on the network cannot be efficiently searched in real time.

  For example, when searching for information satisfying an arbitrary search condition from all information disclosed on the P2P network, it is necessary to transmit a search request to all nodes by broadcasting. If such a search is simultaneously performed by a large number of nodes in the P2P network, the communication efficiency of the network decreases.

  Further, when anonymity enhancement such as onion routing is performed on a P2P network, there is a problem that information cannot be effectively cached on the network. That is, in a network other than P2P, information to be communicated is cached in a node that relays the information, so that subsequent accesses to the same information can be made more efficient. However, when the anonymity of the information sender is enhanced in the communication on the P2P network, even if the transmitted information is cached in an unspecified number of nodes on the P2P network, the cached information is the information sender. Lost relationship with. Therefore, two-way communication cannot be performed between the information sender and the receiver through the cached information.

  In addition, the amount of information on the network tends to increase, and if publicly available information is cached as it is at each node, the load on each node becomes excessive. For this reason, it is conceivable to cache public information metadata (data indicating characteristics of public information). When the metadata of public information is cached, it is necessary to be able to acquire the substance of the public information by accessing the information transmission side node from the information reception side node referring to the metadata.

  However, when anonymity is strengthened as described above, the relationship between cached information and the sender of the information is lost. For this reason, it is impossible to access the information sender side node from the information receiving side node and acquire the substance of the public information. That is, in the P2P network with enhanced anonymity, it has been difficult to improve the efficiency of information retrieval by caching information.

  The present invention has been made in view of these points, and an object thereof is to provide an information search method, an information search apparatus, and an information search program that can improve information search efficiency in a P2P network.

  In order to solve the above-described problem, the first aspect of the present invention provides an information search method for searching information published on a peer-to-peer network as shown in FIG. In this information search method, when the public information storage unit 1a of the information search device 1 receives the information disclosure request 7 including the public information from another device, the public information is stored in the public information storage unit 1b. At this time, the relationship between the devices in the network is defined in a tree structure, and the information disclosure request transfer means 1c of the information search device 1 transfers the information disclosure request 7 to the parent device 6 in the tree structure. When the search condition storage unit 1d of the information search apparatus 1 receives the information search request 8 including the search condition from another apparatus, the search condition storage unit 1d stores the search condition in the search condition storage unit 1e. At this time, the information search request transfer means 1f of the information search device 1 transfers the information search request 8 to the parent device 6 in the tree structure. Thereafter, the search means 1g of the information search apparatus 1 searches the public information stored in the public information storage means 1b based on the search conditions stored in the search condition storage means 1e. When the public information matches the search, the search result notification unit 1 h of the information search device 1 transmits the public information to the search source device 3 that is the transmission source of the information search request 8.

  According to such an information search method, when the information disclosure request 7 is received from another device, the disclosure information is stored in the disclosure information storage unit 1 b and the information disclosure request 7 is transferred to the parent device 6. When the information search request 8 is received from another device, the search condition is stored in the search condition storage unit 1 e and the information search request 8 is transferred to the parent device 6. Thereafter, the public information stored in the public information storage unit 1b is searched based on the search conditions stored in the search condition storage unit 1e. When the public information matches the search, the public information is transmitted to the search source device 3 that is the transmission source of the information search request 8.

  Further, in the second aspect of the present invention, in order to solve the above-mentioned problem, in the information search method for searching information published on a peer-to-peer network, a publication source device that is a transmission source of the information disclosure request is In response to an information disclosure instruction, at least one information retrieval device is selected from a plurality of information retrieval devices in the network, and the information disclosure request is transmitted to the selected information retrieval device by anonymous communication. The search source device that is the transmission source of the information search request selects at least one information search device from among the plurality of information search devices in the network in response to an information search instruction, and selects the information search device. The information search device including the search condition is transmitted to the information search device by anonymous communication, and each of the information search devices constituting the network is transmitted. The public information storage means stores the public information in the public information storage means when the public information storage means receives the public information request including the public information from another apparatus, and the public information storage request transfer means sends the public information request to the public information storage means. When the search condition storage means receives an information search request including a search request from another apparatus, the search condition storage means stores the search condition in the search condition storage means, The search request transfer means transfers the information search request to another adjacent information search device, and the search means stores the information in the public information storage means based on the search conditions stored in the search condition storage means. The search result notification means transmits the search result to the search source device by anonymous communication when the public information matches the search condition. Information search method according to is provided.

  According to such an information search method, at least one information search device is selected from a plurality of information search devices in response to an information disclosure instruction by the publishing source device, and the selected information search device is selected. An information disclosure request is transmitted by anonymous communication. The search source device selects at least one information search device from a plurality of information search devices in response to an information search instruction, and an information search request including a search condition is sent to the selected information search device. Sent by anonymous communication. In each information retrieval device, when an information disclosure request including disclosure information is received from another device, the disclosure information is stored in the disclosure information storage unit, and the information disclosure request is transmitted to another adjacent information retrieval device. Forwarded. When an information search request including a search request is received from another device, the search condition is stored in the search condition storage means, and the information search request is transferred to another adjacent information search device. Further, based on the search condition stored in the search condition storage means, the public information stored in the public information storage means is searched, and when the public information matches, the search result is transmitted to the search source device by anonymous communication. Is done.

  In the third aspect of the present invention, in order to solve the above-mentioned problem, an information search apparatus for searching information published on a peer-to-peer network receives an information disclosure request including public information from another apparatus. A relationship between the public information storage means for storing the public information in the public information storage means and the devices in the network is defined in a tree structure, and the information disclosure request is sent to the parent device in the tree structure. An information disclosure request transfer means for transferring the information, a search condition storage means for storing the search condition in a search condition storage means when receiving an information search request including a search request from another device, and the information search Based on a search condition stored in the search condition storage means and an information search request transfer means for transferring a request to the parent device in the tree structure, the public search A search unit that searches the public information stored in the information storage unit, and a search that transmits a search result to a search source device that is a transmission source of the information search request when the public information matches the search condition. And a result notifying means.

According to such an information search apparatus, the process related to the information search method shown in the first aspect is realized on the information search apparatus.
According to a fourth aspect of the present invention, there is provided an information search program for searching information published on a peer-to-peer network in order to solve the above problem. When an information disclosure request including public information is received from a device, the public information is stored in a public information storage unit, and a relationship between the devices in the network is defined in a tree structure, and an information disclosure request transfer unit When the information disclosure request is transferred to the parent device in the tree structure and the search condition storage means receives an information search request including a search request from another apparatus, the search condition storage means performs the search. A condition is stored, the information search request transfer means transfers the information search request to the parent device in the tree structure, and the search means stores the search condition storage unit. The public information stored in the public information storage means is searched based on the search conditions stored in the search information, and the search result notification means transmits the information search request when the public information matches the search conditions. There is provided an information search program characterized in that a search result is transmitted to a search source apparatus that is an original, and a process is executed.

  If the computer is operated according to such an information search program, the processing related to the information search method shown in the first aspect is realized on the computer.

  As described above, in the first, third, and fourth aspects of the present invention, the relationship between devices in the network is defined by a tree structure, received public information is stored, transmitted to the parent device, and received. The search conditions are stored and transmitted to the parent device. Furthermore, when public information that matches the stored search conditions is stored, the public information is transmitted to the transmission source of the information search request. As a result, in the peer-to-peer network, it is possible to search for all information published in the network only by searching for public information stored in a device positioned higher in the tree structure of the search source device. As a result, search efficiency is improved.

  Further, in the second aspect of the present invention, the publishing source device transmits an information disclosure request to one of the plurality of information search devices by anonymous communication, and the search source device transmits the plurality of information by anonymous communication. An information search request is transmitted to one of the search devices. Each information search device stores the received information disclosure request and information search request, and transfers them to other adjacent devices. When the public information matches the search condition, the search result is transmitted to the search source device. Thereby, it is possible to perform efficient information retrieval on a peer-to-peer network while maintaining anonymity.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, the outline of the invention applied to the embodiment will be described, and then the specific contents of the embodiment will be described.

  FIG. 1 is a conceptual diagram of the invention applied to the embodiment. FIG. 1 shows an information search apparatus 1 that searches information published on a peer-to-peer network. The information search apparatus 1 includes a public information storage unit 1a, a public information storage unit 1b, an information disclosure request transfer unit 1c, a search condition storage unit 1d, a search condition storage unit 1e, an information search request transfer unit 1f, a search unit 1g, and It has a search result notification means 1h.

  In addition, the relationship between devices on the network is defined in a tree structure. For example, child devices 4 and 5 and a parent device 6 for the information search device 1 are defined. Then, an information disclosure request 7 and an information search request 8 are passed to each device constituting the tree structure. In the example of FIG. 1, the information disclosure request 7 is transmitted from the disclosure source device 2, and the information search request 8 is transmitted from the search source device 3.

  When the public information storage unit 1a receives the information disclosure request 7 including the public information from another device, the public information storage unit 1a stores the public information in the public information storage unit 1b. For example, an information disclosure request 7 is passed from the child device 4 in the tree structure.

  The public information storage unit 1b is a storage area in a recording medium capable of storing information readable by a computer. The public information stored in the public information storage unit 1b can be deleted when a predetermined condition such as not being used for a certain period is satisfied, as in the information cache processing.

  The information disclosure request transfer means 1c transfers the received information disclosure request 7 to the parent device 6 in the tree structure. In this way, each device constituting the tree structure transfers the information disclosure request 7 to the parent device, whereby the information disclosure request 7 is transferred to the highest (root) device in the tree structure.

  When receiving the information search request 8 including the search condition from another device, the search condition storage unit 1d stores the search condition in the search condition storage unit 1e. For example, an information search request 8 is passed from the child device 5 in the tree structure.

  The search condition storage unit 1e is a storage area in a recording medium capable of storing information readable by a computer. The search condition stored in the search condition storage unit 1e can be deleted when a predetermined condition such as not being used for a certain period is satisfied, as in the information cache processing.

  The information search request transfer means 1f transfers the information search request 8 to the parent device 6 in the tree structure. In this way, each device constituting the tree structure transfers the information search request 8 to its parent device, whereby the information search request 8 is transferred to the highest device (root) in the tree structure.

  The search means 1g searches the public information stored in the public information storage means 1b based on the search conditions stored in the search condition storage means 1e. For example, when a new search condition is stored in the search condition storage unit 1e, the search unit 1g searches the public information storage unit 1b for public information that matches the search condition. In addition, when new public information is stored in the public information storage unit 1b, the search unit 1g determines whether the public information matches each search condition stored in the search condition storage unit 1e.

  When the public information matches the search condition, the search result notifying unit 1h transmits the search result to the search source device 3 that is the transmission source of the information search request 8 of the corresponding search condition. The search result includes, for example, all or part of the public information that matches the search condition. Further, when the identification information of the disclosure source apparatus 2 that is the transmission source of the public information is stored together with the public information, the identification information may be transmitted to the search source apparatus 3 as a search result. The search source device 3 can access the publication source device 2 based on the identification information of the publication source device 2 and acquire the publication information.

  According to the information search device 1 having such a configuration, when the information disclosure request 7 is received from the child device 4, the public information is stored in the public information storage unit 1b by the public information storage unit 1a. Further, the information disclosure request 7 is transferred to the parent device 6 by the information disclosure request transfer means 1 c.

  When the information search request 8 is received from the slave device 5, the search condition storage unit 1d stores the search condition in the search condition storage unit 1e. Further, the information search request 8 is transferred to the parent device 6 by the information search request transfer means 1f.

  Thereafter, the public information stored in the public information storage means 1b is searched by the search means 1g based on the search conditions stored in the search condition storage means 1e. When the public information matches with the search, the search result notifying unit 1h transmits the search result to the search source device 3 that is the transmission source of the information search request 8.

  In this way, the information disclosure request 7 and the information search request 8 are sequentially transferred to a higher-level device in the tree structure, and the public information and the search conditions are stored in the device that relayed those requests. Therefore, if the publishing source device 2 transmits the information disclosure request 7 to any of the devices constituting the tree structure, the information disclosure request 7 is transferred to the highest-level device. Similarly, if the search source device 3 transmits the information search request 8 of any device constituting the tree structure, the information search request 8 is transferred to the highest device. Therefore, the public information included in the information disclosure request 7 is always a search target based on the search condition included in the information search request 8 in any device on the tree structure. In other words, there is no omission of retrieval of public information.

  In addition, since it is not necessary to send an information search request to all the devices constituting the tree structure, the search efficiency is improved. Further, the search condition is stored in each device, and even if there is information disclosed later, the user of the search source device 3 can perform a search based on the previously stored search condition. It becomes possible to receive the target information as appropriate.

  By the way, when the information disclosure request 7 is transmitted from the disclosure source device 2 to a device (for example, the child device 4) in the tree structure, it can be transmitted via the anonymous communication path. Similarly, when the information search request 8 is transmitted from the search source device 3 to a device in the tree structure (for example, the child device 5), it can be transmitted via an anonymous communication path. Anonymous communication through the anonymous communication path can be performed by, for example, onion routing technology. In onion routing, each device that relays a packet can know the next transfer destination of the packet by decrypting predetermined information with its own encryption key. That is, the encryption key can be distributed to an unspecified number. Therefore, the vulnerability of anonymization due to the concentration of the encryption key can be eliminated.

  When the information disclosure request 7 or the information search request 8 is transferred via the anonymous communication path, information on the anonymous communication path is stored together with the public information and the search condition. When the public information is hit by the search, the search result notifying unit 1h transmits to the search source device 3 including the anonymous communication path and the identification information of the child device 4 when the public information is transferred. At this time, it is transmitted via the anonymous communication path stored together with the search condition. Thereby, the search source device 3 can know the anonymous communication path for accessing the disclosure source device 2. As a result, two-way communication can be performed anonymously between the publishing source device 2 and the searching source device 3 after the search.

  Next, embodiments of the present invention will be specifically described. In the following embodiment, the metadata of information to be disclosed is called an onion reference, and this onion reference is cached at each node on the P2P network. The node that searches for information transmits a search agent that searches for information in each node, and caches this search agent at each node on the P2P network.

  FIG. 2 is a diagram illustrating a network configuration example according to the present embodiment. The P2P network 10 includes a plurality of nodes 100, 200, 310, 320, 330, 340, and 350. Each node 100, 200, 310, 320, 330, 340, 350 is connected to an adjacent node. The nodes 100, 200, 310, 320, 330, 340, and 350 are devices having a function as a computer.

  FIG. 3 is a diagram illustrating a hardware configuration example of a node used in the embodiment of the present invention. The node 100 is entirely controlled by a CPU (Central Processing Unit) 101. A random access memory (RAM) 102, a hard disk drive (HDD) 103, a graphic processing device 104, an input interface 105, and a communication interface 106 are connected to the CPU 101 via a bus 107.

  The RAM 102 temporarily stores at least part of an OS (Operating System) program and application programs to be executed by the CPU 101. The RAM 102 stores various data necessary for processing by the CPU 101. The HDD 103 stores an OS and application programs. Onion references and search agents are stored in the RAM 102 and the HDD 103.

  A monitor 11 is connected to the graphic processing device 104. The graphic processing device 104 displays an image on the screen of the monitor 11 in accordance with a command from the CPU 101. A keyboard 12 and a mouse 13 are connected to the input interface 105. The input interface 105 transmits a signal transmitted from the keyboard 12 or the mouse 13 to the CPU 101 via the bus 107.

  The communication interface 106 is connected to the P2P network 10. The communication interface 106 transmits / receives data to / from other nodes via the P2P network 10.

  With the hardware configuration as described above, the processing functions of the present embodiment can be realized. Although FIG. 3 shows the hardware configuration of the node 100, the other nodes 200, 310, 320, 330, 340, and 350 can be realized with the same hardware configuration.

First, the concept of a search system by caching an onion reference and a search agent will be described.
FIG. 4 is a conceptual diagram showing information retrieval in the embodiment of the present invention. The anonymous P2P information sharing system according to the present invention is a mechanism that efficiently and anonymously searches for transmission information held by each node of a P2P network. The search function between nodes is performed using an anonymous function such as onion routing.

In the example of FIG. 4, it is assumed that the node 100 publishes information and the node 200 searches for the published information.
Information disclosure is performed based on an information publisher's instruction to the information disclosure processing unit 110 in the node 100. Information to be disclosed is stored in the node 100. Onion references 311, 321, 331 are transmitted from the node 100 via the network, and are registered in the nodes 310, 320, 330. The onion references 311, 321, 331 are information (metadata) indicating the characteristics of the disclosed information. The onion references 311, 321, 331 include management information such as the creation date of public information, keywords in the information, and the like. The onion references 311, 321, 331 include information related to the communication route to the node 100 that is the information disclosure source. The onion references 311, 321, and 331 can include the entire information to be disclosed.

  The registered onion references 311, 321 and 331 are to be searched. Further, the registered onion references 311, 321, 331 are deleted when a predetermined condition is satisfied (for example, when an elapsed time since the last use exceeds a predetermined time). That is, the onion references 311, 321, 331 are information cached in the nodes 310, 320, 330.

  The information search is performed based on an information searcher instruction to the information search processing unit 210 in the node 200. When a search condition is input to the node 200, search agents 341, 351, 332 are transmitted from the node 200 via the network, and the search agents 341, 351, 332 are registered in the other nodes 340, 350, 330. The The search agents 341, 351, and 332 are functions for searching onion references in registered nodes based on specified search conditions. Note that the search agents 341, 351, and 332 include information related to the communication route to the node 200 that is the information search source.

  The search agents 341, 351, and 332 search the onion references in the nodes 340, 350, and 330 at the time of registration. Also, the search agents 341, 351, 332 search for onion references registered later. When an onion reference that matches the search condition is detected, the search agents 341, 351, and 332 notify the search source node 200 of the information of the onion reference. The registered search agents 341, 351, 332 are deleted when a predetermined condition is satisfied (for example, when an elapsed time since the last use has exceeded a predetermined time). That is, the search agents 341, 351, 332 are information cached in the nodes 340, 350, 330.

  Onion references and search agents are cached simultaneously on any node on the network. In the example of FIG. 4, the onion reference 331 and the search agent 332 are cached at the node 330. Then, the onion reference 331 is targeted by the search processing by the search agent 332. At this time, if the onion reference 331 matches the search condition in the search agent 332, the onion reference 331 is detected (search hit).

  The search agent 332 that has detected the onion reference 331 notifies the information search processing unit 210 of the node 200 of the onion reference 331 and information on the communication route from the node 200 to the node 330. Thereby, the searcher who uses the node 200 can know that information satisfying the search condition is disclosed in the node 100.

  The onion reference 331 includes information on the communication route from the node 330 to the node 100, and the communication route from the search agent 332 to the node 330 to the node 200 is notified. To the node 100 can be known.

  By the way, in the embodiment of the present invention, a parent-child relationship on a tree structure is defined for a connection relationship between nodes in order to efficiently perform an onion reference search by a search agent. For example, a node that newly joins the P2P network transmits a connection request to any node that has already joined the P2P network. By permitting the transmitted connection request, the node that has output the connection request becomes a new node on the P2P network. Therefore, in this embodiment, a node that has transmitted a connection request is defined as a child node, and a node that has permitted connection is defined as a parent node.

  FIG. 5 is a diagram illustrating a tree structure of a network. The P2P network shown in FIG. 5 includes a plurality of nodes 21 to 33. The nodes that can communicate are connected with a solid line. When there is a parent-child relationship in the tree structure, the parent-child relationship is indicated by a solid line arrow connecting the nodes. The arrow points from the parent node to the child node.

  In the example of FIG. 5, the node 21 is the highest node (root node) on the tree structure. The root node is installed, for example, by an organization that manages service provision when starting operation of the P2P network. A node participating in the P2P network needs to connect directly to the root node or to a node already participating in the P2P network.

  Nodes 22 and 23 are connected to the node 21 as child nodes. Nodes 24 and 25 are connected to the node 22 as child nodes. Nodes 26 and 27 are connected to the node 23 as child nodes. A node 28 is connected to the node 24 as a child node. A node 29 is connected to the node 25 as a child node. A node 30 is connected to the node 26 as a child node. A node 31 is connected to the node 27 as a child node. A node 32 is connected to the node 29 as a child node. A node 33 is connected to the node 31 as a child node.

In the present embodiment, a server for managing the tree structure is not prepared at the center, and the tree structure is autonomously configured by exchanging information between nodes as follows.
Basically, when a node is newly connected to the P2P network, the node that outputs the connection request is related as the child node, and the node that received the connection request is related as the parent node.

  Further, when configuring a tree structure, the basic configuration is n branches (n is a natural number). The n-branch means that the number of connected nodes adjacent to one node is n. Although there are cases where the n-branch does not instantaneously occur during the transition of the configuration, the n-branch can be stabilized over time by updating the routing table or the like. As a method of stabilizing by n-branch, it is conceivable to reduce the number of sibling nodes as much as possible and not to deepen the tree structure hierarchy.

  That is, each node manages at least a parent-child relationship with a node adjacent to itself. In addition, for each node, information such as which hierarchy it is in and the child nodes have some information, and that information is also shared when exchanging routing tables. Each node manages the hierarchy, so that a newly connected partner is notified to connect to a node with as few upper nodes as possible. When the number of child nodes of the recognized node is full of the limit value, information on both the upper node and the lower node is notified. In that case, the connecting node first tries to connect to a lower node.

  In addition, limit the hierarchy and do not connect further down. As the limit value, for example, an initial value is set to 6, and the administrator of the node can be changed within a predetermined range. When a new node is connected, there may be a case where there is no node that can have a child node in the recognized node. In that case, the node newly participating in the tree structure tries to connect to the upper node of the recognized node while changing the connection target. Similarly, when the process is performed up to the highest level, a node newly participating in the tree structure tries to connect while changing the connection target from the highest level node to a lower level node.

  When a node having a child node disappears from the network (for example, when the operation of the node stops), each child node tries to connect to the parent node of the lost node. The previously accepted node is placed at the position of the lost node in the tree structure. Nodes accepted late are treated the same as the connection logic of the new node.

The tree structure is optimized by performing the following processing.
If the private IP node is higher than the global IP node in the tree structure, the private IP node is moved downward. Further, the private IP node is caused to function as a server node by polling or the like.

In addition, the communication time between adjacent nodes (from the start to the end of session connection) is measured, and the higher the speed and the higher the performance of the node, the lower the speed of the node.
In this way, the tree structure can be optimized. If the relationship between nodes is defined in a tree structure, transmission of onion references and transmission of search agents can be performed toward higher nodes in the tree structure. Thus, the onion reference and the search agent can be reliably merged on any node without transmitting the onion reference or broadcasting the search agent.

  Moreover, in the present embodiment, a temporary public source and a temporary search source can be set in order to maintain anonymity between the public source and the search source. Anonymity of data communication between the publisher and the temporary publisher is enhanced by onion routing. Similarly, anonymity of data communication between the search source and the temporary search source is enhanced by onion routing.

  FIG. 6 is a conceptual diagram of information retrieval using a tree structure. In the example of FIG. 6, a P2P network including a plurality of nodes 41 to 63 is shown. In this P2P network, a tree structure having the node 41 as a root node is defined. Here, the node 42 is a public source, and the node 51 is a search source.

  When transmitting information to be disclosed, the node 42 first selects a provisional publication source. Any node in the P2P network can be a temporary publisher. For example, the node 42 acquires information on a node recognized by the node from other nodes recognized by the node 42 itself. Then, the node 42 selects an arbitrary node from the acquired node information (for example, node ID and IP address), and sets it as a temporary publication source. In this example, it is assumed that the node 52 is selected as a temporary publication source.

  Next, the node 42 searches for an anonymous communication path to the temporary publisher. In the example of FIG. 6, packets can be delivered in the order of the node 56, the node 57, the node 58, the node 59, and the node 52. The node 42 acquires the public keys of the nodes 52 and 56 to 59 at the time of route search. Then, the node 42 generates a packet to be transferred along the detected route. At this time, using the public key of each of the nodes 52 and 56 to 59, a packet to which onion routing technology is applied is generated. The generated packet includes an onion reference of public information.

  The node 42 passes the generated packet to the adjacent node 56 on the anonymous communication path. Then, the packet is transferred by onion routing, and passed to the node 52 selected as a temporary public source.

  In onion routing, each relaying node decrypts the packet route information (onion route) with its own secret key, thereby knowing the next transfer destination node. At this time, the relay node can know only the adjacent node that has transferred the packet and the adjacent node to which the packet is to be passed. In other words, the relay node cannot know the source node or destination node of the packet. Thereby, the anonymity of the transmission source and the destination of the packet is ensured.

  Further, each relaying node transfers the packet while generating return route information when transferring in the reverse direction of the packet. That is, each node encrypts its own identification information (IP address or the like) with the public key of the adjacent node to which the packet is transferred and adds it to the packet to be transferred. Thus, return route information is constructed by including each node's own identification information in a packet in a format that only the adjacent nodes can decode. The return route information is used as an onion route during packet transfer in the reverse direction.

  The destination node 52 can know that the destination is itself by decrypting the received packet with its own private key, and can obtain an onion reference. When the node 52 receives the onion reference addressed to itself, the node 52 caches the onion reference. As a result, the onion reference 71 is held in the node 52. The onion reference 71 includes return route information to the node 42 that is the publication source.

  Further, the node 52 passes the onion reference including the return route information to the node 46 corresponding to the parent in the tree structure. The node 46 caches the received onion reference. As a result, the onion reference 72 is held in the node 46.

  Similarly, the node 46 passes the onion reference including the return route information to the node 43 corresponding to the parent. The node 43 caches the received onion reference. As a result, the onion reference 73 is held in the node 43.

  Similarly, the node 43 passes the onion reference including the return route information to the node 41 corresponding to the parent. The node 41 caches the received onion reference. As a result, the onion reference 74 is held in the node 41.

In this way, the onion reference is cached in each node on the path from the temporary public source node 52 to the root node 41.
Next, an information search procedure will be described.

  When searching for information, the node 51 first selects a temporary search source. Any node in the P2P network can be a temporary search source. For example, the node 51 acquires information on a node recognized by the other node from another node recognized by the node 51 itself. Then, the node 51 selects an arbitrary node from the acquired node information (for example, IP address) and sets it as a temporary search source. In this example, it is assumed that the node 55 is selected as a temporary search source.

  Next, the node 51 searches for an anonymous communication path to a temporary search source. In the example of FIG. 6, packets can be delivered in the order of the node 60, the node 61, the node 62, the node 63, and the node 55. The node 51 acquires the public key of each of the nodes 55 and 60 to 63 during route search. Then, the node 51 generates a packet to be transferred along the detected route. At this time, the node 51 uses the public key of each of the nodes 55 and 60 to 63 to generate a packet to which the onion routing technique is applied. The generated packet includes a search agent.

  The node 51 passes the generated packet to the adjacent node 60. Then, the packet is transferred by onion routing, and passed to the node 55 selected as a temporary search source. The method of onion routing is the same as in the case of transmitting an onion reference. When a packet is relayed, return route information for transferring the same route in the reverse direction is generated and added to the packet.

  The destination node 55 can know that the destination is itself by decrypting the received packet with its own private key, and can acquire a search agent. When the node 55 receives the search agent addressed to itself, the node 55 caches the search agent. As a result, the search agent 81 is held in the node 55. This search agent 81 includes return route information to the search source node 51.

  Further, the node 55 passes the search agent including the return route information to the node 47 corresponding to the parent in the tree structure. The node 47 caches the received search agent. As a result, the search agent 82 is held in the node 47.

  Similarly, the node 47 passes the search agent including the return route information to the node 43 corresponding to the parent. The node 43 caches the received search agent. As a result, the search agent 83 is held in the node 43.

  Similarly, the node 43 passes the search agent including the return route information to the node 41 corresponding to the parent. The node 41 caches the received search agent. As a result, the search agent 84 is held in the node 41.

In this way, the search agent is cached in each node on the route from the temporary public source node 52 to the route node 41.
The search agent cached in each node executes a search process with the onion reference cached in the corresponding node as a search target. When the information published by the node 42 matches the search condition instructed by the information searcher to the node 51, the search agent 83 of the node 43 detects the onion reference 73.

  When the onion reference 73 is detected, a packet for transferring the search result to the search source node 51 is generated using the return route information included in the search agent 83. The contents of the onion reference 73 are included in the packet. The generated packet is transferred in the order of the node 63, the node 62, the node 61, the node 60, and the node 51. As a result, the onion reference can be acquired at the node 51.

  The onion reference is associated with return route information from the node 42 to the node 52, and this return route information is also included in the search result. Thereby, the node 51 can acquire the anonymous communication path to the node 42 and can access the information published by the node 42 via the anonymous communication path.

  As described above, in this embodiment, a hierarchical tree structure is constructed as a partial structure of the node configuration of the P2P network in order to efficiently search all cases regardless of transmission of all P2P multicast messages. Onion references are sequentially cached from a node selected at random to an upper node. On the search side, the search agent is sequentially cached from the node selected at random to the upper node. The cached search agent searches for onion references in the cached nodes.

  Both the onion reference and the search agent are sequentially transferred to the upper level of the tree structure and cached at the relayed node, so that the onion reference and the search agent meet on any node in the tree structure. be able to. That is, the information published by the node 42 can be detected from the node 51 without transmitting an onion reference or a search agent by broadcasting. As a result, efficient information retrieval on the P2P network becomes possible.

  In addition, since the temporary publisher and temporary search source are set, the anonymity of the information provider and the information searcher is protected. That is, since anonymous communication is performed between the publishing source node 42 and the temporary publishing source node 52, the relaying nodes 56 to 59 cannot know the publishing source and the tentative publishing source.

  Further, by generating return onion information when performing anonymous communication from the publishing source node 42 to the temporary publishing source node 52, an anonymous communication path from the searching source to the publishing source is generated after a search hit. Can do.

  Note that a double notification to the search source node can be prevented by propagating a search stop message to the search agent that has been hit from the node hit by the search to the upper side. In addition, the node hit by the search can obtain the entity information from the node of the publishing source using the found onion reference. Then, the obtained public information entity may be transmitted to the search source node using an onion route (indicating an anonymous communication path in onion routing) to the search source node.

Next, processing functions that each node should have in order to realize information retrieval using a tree structure relationship will be specifically described.
FIG. 7 is a block diagram showing processing functions in the node. The node 100 includes an information disclosure processing unit 110, an information search processing unit 120, a search engine 130, a public information cache unit 140, a temporary disclosure source node selection unit 150, a search agent cache unit 160, a temporary search source node selection unit 170, a routing unit. 180 and a node management table 190.

  Among these elements, the information disclosure processing unit 110, the search engine 130, the public information cache unit 140, and the temporary disclosure source node selection unit 150 constitute an information disclosure function. The information search processing unit 120, the search engine 130, the search agent cache unit 160, and the temporary search source node selection unit 170 constitute an information search function.

  The information disclosure processing unit 110 performs information disclosure processing based on an operation input from the information publisher. Specifically, the information disclosure processing unit 110 holds information to be disclosed and transmits the information in response to a request from another node. Note that the information to be disclosed is stored in, for example, an HDD.

  Furthermore, the information disclosure processing unit 110 requests the temporary publication source node selection unit 150 to select a node that operates as a temporary publication source. Further, when receiving the information disclosure instruction, the information disclosure processing unit 110 requests the public information cache unit 140 to transmit an onion reference.

  The information search processing unit 120 performs information search via the P2P network based on operation input from the information searcher. Specifically, the information search processing unit 120 accepts input of search conditions. When receiving the information search execution instruction, the information search processing unit 120 requests the temporary search source node selection unit 170 to select a node that operates as the temporary search source. In addition, the information search processing unit 120 requests the search agent cache unit 160 to perform search agent transmission processing.

  The search engine 130 searches for information according to the search agent using the onion reference as a search target. Specifically, when receiving the onion reference from the public information cache unit 140, the search engine 130 stores the onion reference (for example, stores it in a storage device such as the RAM 102 or the HDD 103). When the search engine 130 receives a search agent from the search agent cache unit 160, the search engine 130 stores the search agent (for example, stores it in a storage device such as the RAM 102 or the HDD 103).

  Then, the search engine 130 starts the stored search agent at a predetermined timing, and executes a search for the stored onion reference. Specifically, when a search agent is newly stored, the search engine 130 activates the search agent. The search target at that time is all onion references already stored.

  Further, when the search engine 130 stores a new onion reference, it starts all the search agents already stored at that time. The search target at that time is a newly stored onion reference.

  When an onion reference that matches the search condition is detected in the search by the search agent, the search engine 130 notifies the search source node of the search result. The search result includes information such as an onion reference and an anonymous communication path to the node of the publishing source.

  Upon receiving the onion reference transmission request from the information disclosure processing unit 110, the public information cache unit 140 generates an onion reference including metadata (creation date, keyword, etc.) regarding information to be disclosed.

  Further, the public information cache unit 140 acquires the node ID or IP address of the node selected as the temporary public source node from the temporary public source node selection unit 150. Then, the public information cache unit 140 requests the routing unit 180 to search for an anonymous communication path to the temporary public source node. When the public information cache unit 140 receives the anonymous communication path from the routing unit 180, the public information cache unit 140 transmits an onion reference to the temporary public source node via the anonymous communication path.

Also, when the public information cache unit 140 receives an onion reference from another node, the public information cache unit 140 passes the onion reference to the search engine 130 and caches it. Thereafter, the public information cache unit 140 transmits the received onion reference to the parent node. A cached onion reference has the following information:
Onion route from the cached node to the publishing source node Temporary identifier for indicating that multiple references represent the same entity Information to be transmitted or metadata indicating the content of the information. In the latter case, the information entity is placed in the node of the publishing source.

The onion reference is cached in a plurality of nodes on the P2P network by being sequentially transferred to the parent node in the tree structure. Here, two types of lifetimes can be set in the onion reference cache.
-Disappears after a set time has elapsed from the time the poster first posted (it will disappear someday).
-When the set time elapses from the newly cached time, it disappears (search target remains).

The public information cache unit 140 deletes the onion reference that has reached the end of its life from the search engine 130.
Upon receiving a request for selecting a node as a temporary publication source from the information disclosure processing unit 110, the temporary publication source node selection unit 150 performs a process of selecting a node as a temporary publication source. For example, the temporary disclosure source node selection unit 150 refers to the node management table 190 and acquires the IP address of a node located 7 hops away from itself. Then, based on the acquired IP address, the temporary publication source node selection unit 150, for a node that is 7 hops away, a list of IP addresses of nodes that are further 7 hops away from the node (temporary publication source node selection candidate) List). When the temporary release source node selection candidate list is returned, the temporary release source node selection unit 150 selects one IP address from the temporary release source node selection candidate list. The node corresponding to the selected IP address becomes the temporary disclosure source node. When the temporary publication source node is selected, the temporary publication source node selection unit 150 notifies the public information cache unit 140 of the IP address of the temporary publication source node.

  In addition, when the provisional publication source node selection candidate 150 receives a provisional publication source node selection candidate list acquisition request from another node, the provisional publication source node selection candidate list is generated and responds to the request source. Specifically, the temporary disclosure source node selection unit 150 refers to the node management table 190 in response to the request for acquisition of the temporary disclosure source node selection candidate list, and extracts the IP addresses of the nodes separated by 7 hops. Then, the temporary disclosure source node selection unit 150 transmits the IP address list as a temporary disclosure source selection candidate list as a response to the transmission source of the acquisition request.

  When the search agent cache unit 160 receives a search agent transmission request from the information disclosure processing unit 110, the search agent cache unit 160 generates a search agent that searches for an onion reference corresponding to the specified search condition. In addition, the search agent cache unit 160 acquires the IP address of the node selected as the temporary search source node from the temporary search source node selection unit 170. Then, the search agent cache unit 160 requests the routing unit 180 to search for an anonymous communication path to the temporary search source node. When the search agent cache unit 160 receives the anonymous communication path from the routing unit 180, the search agent cache unit 160 transmits the search agent to the temporary search source node via the anonymous communication path.

  When the search agent cache unit 160 receives a search agent from another node, the search agent cache unit 160 passes the search agent to the search engine 130 and caches it. Thereafter, the search agent cache unit 160 transmits the received search agent to the parent node.

  The search agent is cached in each node while being transferred to the upper node of the tree structure. When the search agent cache unit 160 caches the search agent, it also stores an onion route indicating an anonymous communication path to the search source node. The cached search agent searches the onion reference in the search engine 130 at the time of caching. If an onion reference is stored after the search agent cache, it is determined whether the onion reference meets the search condition. If the search condition is hit, the search engine 130 notifies the search source node of the search result.

  The lifetime of the search agent cache can be set. For example, when the set time elapses from the time when the searcher first searches, the searcher disappears (someday disappears). Specifically, the search agent cache unit 160 deletes a search agent that has reached the end of its life from the search engine 130.

  When the temporary search source node selection unit 170 receives a selection request for a node as a temporary search source from the information disclosure processing unit 110, the temporary search source node selection unit 170 performs a process of selecting a node as a temporary search source. Specifically, the temporary search source node selection unit 170 refers to the node management table 190 and acquires the IP address of a node located at a position 7 hops away from itself. Then, based on the acquired IP address, the temporary search source node selection unit 170, for a node that is 7 hops away, a list of IP addresses of nodes that are further 7 hops away from the node (temporary search source node selection candidates) List). When the temporary search source node selection candidate list is returned, the temporary search source node selection unit 170 selects one IP address from the temporary search source node selection candidate list. The node corresponding to the selected IP address becomes the temporary search source node. After selecting the temporary search source node, the temporary search source node selection unit 170 notifies the search agent cache unit 160 of the IP address of the temporary search source node.

  In addition, when receiving a request for acquiring a temporary search source node selection candidate list from another node, the temporary search source node selection unit 170 generates a temporary search source node selection candidate list and responds to the request source. Specifically, the temporary search source node selection unit 170 refers to the node management table 190 in response to the request for acquiring the temporary search source node selection candidate list, and extracts the IP addresses of the nodes separated by 7 hops. Then, the temporary search source node selection unit 170 transmits the IP address list as a temporary search source selection candidate list as a response to the transmission source of the acquisition request.

  The routing unit 180 performs packet routing. For example, it is possible to perform routing that ensures the anonymity of the caller and the destination by using onion routing. The routing unit 180 exchanges node information on the P2P network with other connected nodes. Then, the routing unit 180 registers information on the node whose existence has been confirmed in the node management table 190.

  The routing unit 180 can search for an anonymous communication path to a designated node. For example, when the routing unit 180 receives a request for searching for an anonymous communication path up to the temporary disclosure source node from the public information cache unit 140, the routing unit 180 searches for the anonymous communication path and sets an onion route indicating the anonymous communication path to the public information cache unit 140. To pass. Similarly, when the routing unit 180 receives a search request for an anonymous communication path up to the temporary search source node from the search agent cache unit 160, the routing unit 180 searches for an anonymous communication path and obtains an onion route indicating the anonymous communication path as a search agent cache unit. To 160.

  The node management table 190 is a management table in which information regarding nodes that have been confirmed to exist on the P2P network is registered. Note that the node management table 190 in this embodiment also serves as a routing table for packet routing. In the P2P network, since the IP address is often not fixed, each node can obtain the latest IP address of each node by exchanging information in the node management table.

  FIG. 8 is a diagram illustrating an example of the data structure of the node management table. The node management table 190 includes a node ID, an IP address, a port number, the number of hops, an adjacent node obtained by merging the tables, a communication speed with the own node, a node setting speed or a communication speed with a fixed server, and a data encryption processing speed. Information on the number of message relays per unit time, whether private or global, parent / child relationship with oneself, hierarchical level, and number of child nodes is registered for each node that has been confirmed to exist. In FIG. 8, pieces of information arranged in the horizontal direction are associated with each other to form a record of one node. Hereinafter, in the description of information in each item, a node corresponding to the information is referred to as a corresponding node. Further, the node 100 in which the node management table 190 is provided is referred to as a local node.

The node ID is a name for uniquely identifying each node on the P2P network.
The IP address is an address on the network of each node.
The port number is an identification number indicating an application used for communication when communication is performed from the corresponding node.

  The number of hops is the number of hops (hop count) from the own node to the corresponding node. The number of hops is a numerical value indicating how many nodes the packet passes through before reaching the corresponding node. The number of hops of the own node is 0, and the number of hops of the adjacent node is 1.

  The adjacent node into which the tables are merged is an adjacent node to which a packet for communicating with the corresponding node should be passed. In this item, the node ID of the corresponding adjacent node is set.

The communication speed with the own node is a communication speed between the corresponding node and the own node.
In the item of the node setting speed or the communication speed with the fixed server, when the communication speed is preset in the corresponding node, the communication speed is registered. For example, even a network capable of communication at a speed of 100 Mbps may be limited so that only 20 Mbps at maximum can be used for communication between a node and another node. In that case, a limited communication speed is set. In addition, when accessing a corresponding node via a fixed server, a communication speed with the fixed server may be set in advance. In this case, the communication speed with the fixed server set in advance is set in this item.

The data encryption processing speed indicates how fast the encryption process (data encryption or decryption) is performed when the data encryption process is performed in the corresponding node.
The number of message relays per unit time indicates how many messages can be relayed per unit time.

In the item of private or global, whether the IP address of the corresponding node is a private IP or a global IP address is set.
The parent-child relationship on the tree structure from the self node to the corresponding node is set in the item of the parent-child relationship with the self. The parent-child relationship indicates how many generations ago the ancestor is the ancestor of the own node, and indicates what generation the ancestor is after the generation of the descendant of the own node.

In the hierarchical level, the number of generations after the root (topmost tree structure) node of the corresponding node is indicated.
The number of nodes connected as children of the corresponding node is set as the number of child nodes.

  7 and 8, the functional configuration of the node 100 has been described, but the other nodes also have the same configuration. In the following description, it is assumed that the components of each node other than the node 100 have the same function as the components of the same name in FIG.

By constructing a tree structure with nodes having such functions, information retrieval by an onion reference and a retrieval agent is efficiently performed.
Next, how each element shown in FIG. 7 operates during information disclosure and information search will be described in detail. First, processing performed at each node when information is disclosed will be described.

  FIG. 9 is a diagram showing processing at the time of information disclosure. In the example of FIG. 9, the node 100 is a disclosure source node of public information, and the node 410 is a temporary disclosure source node. In the node 100, the information disclosure processing unit 110 issues a provisional disclosure source node selection request and an information disclosure request. The temporary publication source selection request is passed to the temporary publication source node selection unit 150. The temporary publication source node selection unit 150 selects a node as a temporary publication source from the P2P network. In this example, it is assumed that the node 410 is selected. The temporary disclosure source node selection unit 150 passes the IP address of the selected node 410 to the disclosure information cache unit 140.

  Upon receiving the information disclosure request, the public information cache unit 140 searches for an anonymous communication path to the node 410 corresponding to the IP address passed from the temporary disclosure source node selection unit 150. Then, the public information cache unit 140 transmits an onion reference to the node 410 along the anonymous communication path.

  When the onion reference is passed to the node 410, the public information cache unit 414 in the node 410 passes the onion reference to the search engine 413. The search engine 413 holds the received onion reference 413a. Also, the public information cache unit 414 transfers the onion reference to the parent node in the tree structure.

  FIG. 10 is a diagram showing processing at the time of information retrieval. In the example of FIG. 10, the node 200 is a search source node for information search, and the node 420 is a temporary search source node. In the node 200, the information search processing unit 220 issues a temporary search source node selection request and an information search request. The temporary search source selection request is passed to the temporary search source node selection unit 270. The temporary search source node selection unit 270 selects a node as a temporary search source from the P2P network. In this example, it is assumed that the node 420 is selected. The temporary search source node selection unit 270 passes the IP address of the selected node 420 to the search agent cache unit 260.

  The search agent cache unit 260 that has received the information search request searches for an anonymous communication path to the node 420 corresponding to the IP address passed from the temporary search source node selection unit 270. Then, the search agent cache unit 260 transmits the search agent to the node 420 along the anonymous communication path.

  When the search agent is passed to the node 420, the search agent cache unit 426 in the node 420 passes the search agent to the search engine 423. The search engine 423 holds the received search agent 423a. In addition, the search agent cache unit 426 transfers the search agent to the parent node in the tree structure.

  FIG. 11 is a diagram illustrating processing at the time of a search hit. In the example of FIG. 11, the node 430 shows a case where information published by the node 100 is hit in the search by the node 200. The search engine 433 in the node 430 searches for onion references that match the search conditions indicated by the search agent 433a. When the onion reference 433b hits this search, the search engine 433 transmits the content of the onion reference 433b to the search source node 200 via the anonymous communication path. In the node 200, an anonymous communication path is formed between the public source node and the search source node.

FIG. 12 is a diagram illustrating state transition in the anonymous communication path forming process. In the example of FIG. 12, a tree structure with the node 90 as a root node is formed.
The first state (ST1) is an initial state. Here, the disclosure source is a node 91 and the search source is a node 92. The temporary publication source is the node 93, and the temporary search source is the node 94.

  The next state (ST2) shows a situation where the onion reference is distributed in response to the information disclosure request. The onion reference is cached in each node on the route from the temporary public source node 93 to the root node 90.

  The next state (ST3) shows a situation where a search agent is deployed in response to an information search request. The search agent is cached in each node on the path from the temporary search source node 94 to the root node 90.

  The next state (ST4) shows the formed anonymous communication path. In this example, the search hits each node on the path from the node 95 to the root node 90. In this case, an anonymous communication path is formed via the node 95 which is the lowest element on the tree structure among the nodes hit by the search.

  By the way, the anonymity of communication is enhanced by onion routing being performed between the publishing source node and the temporary publishing source node, and by onion routing being performed between the search source node and the temporary search source node. . However, since the configuration of the P2P network changes dynamically, it is difficult to previously determine a communication route between arbitrary nodes on the server. Therefore, in order to perform onion routing in the P2P network, it is necessary to perform route search processing to the destination node. The route search process will be specifically described below.

  FIG. 13 is a flowchart illustrating a procedure of route search start processing. The route search start process is executed in the routing unit of the publishing source node when the publishing source node searches for an anonymous communication path to the temporary publishing source node. Also, when the search source node searches for an anonymous communication path to the temporary search source node, a route search start process is executed in the routing unit of the search source node. Hereinafter, assuming that the node 100 illustrated in FIG. 7 is a disclosure source node, the processing illustrated in FIG. 13 will be described along with step numbers.

  [Step S <b> 11] The routing unit 180 selects one of the nodes with the longest hop number among the nodes registered in the node management table 190 as a temporary disclosure source node. Furthermore, the routing unit 180 generates a route search packet for searching for an anonymous communication path to the temporary disclosure source node.

  [Step S12] The routing unit 180 generates its own anonymous ID. The generated anonymous ID is recorded in a recording medium such as RAM or HDD. Thereafter, when a packet is received from another node, it is possible to determine whether or not the packet is addressed to itself by comparing the anonymous ID of the destination of the packet with the recorded anonymous ID. . Then, the routing unit 180 sets the generated anonymous ID as a packet transfer history, and sets the anonymous ID as a transmission source of the route search packet. Further, the routing unit 180 generates a return onion and sets it in the route search packet. The anonymous ID is identification information set individually for each series of anonymous communication. Further, as the return onion, for example, information of encrypting its own node ID with its own public key and further adding its own node ID is set.

[Step S13] The routing unit 180 transmits a route search packet to all (global address) adjacent nodes other than the private IP.
FIG. 14 is a diagram illustrating a data structure example of a route search packet. The route search packet 510 includes a message flag 511, a destination (To) 512, a transmission source (From) 513, a destination onion 514, a return onion 515, reply encryption temporary key information 516, and a transfer history 517.

  A message flag 511 indicates the type of packet. In the case of the route search packet 510, information indicating that it is a packet for route search broadcast transmission is set.

In the destination 512, the destination of the route search packet 510 is set. The destination is indicated by identification information (public ID) of the temporary public source node.
In the transmission source 513, the anonymous ID of the transmission source node is set.

The destination onion 514 is information indicating the route to the destination, but is blank in the route search packet 510.
In the return onion 515, a communication path for returning a route notification packet to the route search packet 510 is set by being encrypted in multiple.

  The reply encryption temporary key information 516 is a temporary public key of the public source node and an encrypted temporary secret key that are used when a route notification packet is returned. The temporary public key and the temporary secret key are keys generated for each route search.

  In the transfer history 517, an anonymous ID generated by a packet transmission source node or a node that relays the packet is set. Each node that receives the packet compares the anonymous ID in the transfer history 517 with the anonymous ID generated in the past, and if there is a matching anonymous ID, recognizes that the packet has been transferred in the past it can.

The node that has received the route search packet relays the route search packet or returns a route notification packet.
FIG. 15 is a flowchart illustrating a procedure of route search packet reception processing. In the following, assuming that the node 100 shown in FIG. 7 has received a route search packet, the processing shown in FIG. 15 will be described along with step numbers.

[Step S21] The routing unit 180 receives a route search packet.
[Step S22] The routing unit 180 confirms whether the route search packet is addressed to its own node. By referring to the destination field of the route search packet, it can be determined whether or not it is addressed to the own node.

  [Step S23] If the routing unit 180 is addressed to the own node, the processing proceeds to step S24. If the routing unit 180 is not addressed to the own node, the process proceeds to step S27.

[Step S24] The routing unit 180 generates a route notification packet using the return onion of the route search packet as a destination onion.
[Step S25] The routing unit 180 encrypts the record information of its own node in the node management table 190 with the encryption key of the searcher (public source node) and sets it in the route notification packet.

[Step S26] The routing unit 180 returns a route notification packet to the publishing source node. Thereafter, the process ends.
[Step S27] The routing unit 180 confirms whether or not the anonymous ID of the own node is registered in the transfer history field of the route search packet.

  [Step S28] The routing unit 180 determines whether the route search packet has already passed through its own node. In other words, if the own node's anonymous ID is set in the transfer history field, the node has already passed. If it has passed through its own node, the process proceeds to step S29. If it has not passed through its own node, the process proceeds to step S30.

[Step S29] The routing unit 180 discards the received route search packet and ends the process.
[Step S30] The routing unit 180 sets its own anonymous ID in the transfer history. Further, the routing unit 180 encrypts the original return onion with the private key of its own node, and sets information obtained by adding its own node ID to the encrypted data as a new return onion.

  [Step S31] The routing unit 180 transmits the route search packet to all the adjacent nodes except the node that has transmitted the route search packet and the private IP node. Thereafter, the process ends.

  FIG. 16 is a diagram illustrating a data structure example of a route notification packet. The route notification packet 520 includes a message flag 521, a destination (To) 522, a transmission source (From) 523, a destination onion 524, a return onion 525, route information 526, and reply encryption temporary key information 527.

The message flag 521 indicates the type of packet. In the case of the route notification packet 520, information indicating that it is a route search reply packet is set.
In the destination 522, the destination of the route notification packet 520 is set. The destination is the anonymous ID of the transmission source node set in the transmission source 513 of the route search packet 510.

In the transmission source 523, a public ID (public ID) of the temporary transmission source node is set.
The destination onion 524 is information indicating a route to the destination. This is a copy of the return onion 515 of the route search packet 510 at the receiving Peer. However, in the destination onion 524, information indicating the past transmission path is deleted every time the packet is relayed.

The return onion 525 is blank in the route notification packet 520.
The route information 526 is information indicating a transmission route for anonymous communication. In the route information, the node ID and the fixed public key of each P2P onion node on the transmission route are set by being encrypted with the fixed public key of the transmission source node. The route information 526 also includes temporary key information 516 for reply encryption of the route search packet 510.

In the reply encryption temporary key information 527, the contents of the reply encryption temporary key information 516 of the route search packet 510 are set as they are.
The node that has received the route notification packet performs the relay processing of the route notification packet if it is addressed to another node, and performs the generation processing of the optimum route if it is addressed to itself.

  FIG. 17 is a flowchart showing route notification packet reception processing. In the following, assuming that the node 100 shown in FIG. 7 has received a route notification packet, the processing shown in FIG. 17 will be described along with step numbers.

[Step S41] The routing unit 180 receives a route notification packet.
[Step S42] The routing unit 180 confirms whether or not the route notification packet is addressed to the own node. Whether or not it is addressed to its own node can be determined by whether or not its own anonymous ID is set in the destination field.

  [Step S43] If the routing unit 180 is a route notification packet addressed to its own node, the process proceeds to Step S44. If the routing unit 180 is not a route notification packet addressed to its own node, the processing proceeds to step S45.

  [Step S44] The routing unit 180 decodes the information in the route information field of the route notification packet to generate an optimum route. That is, the route information includes the node ID and the public key of each node on the anonymous communication path in a state encrypted with the public key of the own node (the search source node that has performed the route search to the temporary public source node). include. Further, the array of information of each node in the route information is the array of nodes on the anonymous communication path as it is. Therefore, the array of node IDs obtained by decoding is the optimum route.

[Step S45] The routing unit 180 determines the next node indicated by the destination onion as the packet transmission destination.
[Step S46] The routing unit 180 encrypts the record information of its own node in the node management table 190 with the encryption key of the searcher (public source node), and sets it in the route notification packet.

[Step S47] The routing unit 180 returns a route notification packet to the next node indicated by the destination onion. Thereafter, the process ends.
As described above, the anonymous communication path from the publishing source node to the temporary publishing source node can be searched. The transmission source node generates an onion routing packet (data packet) communicated along the anonymous communication path, and sets the onion reference of the public information as the content (payload). Anonymity of the transmission source node can be maintained by sending the data packet to the temporary disclosure source node via the anonymous communication path.

  Although the above example is an anonymous communication between the transmission source node and the temporary transmission source node, the anonymous communication between the search source node and the temporary search source node can be performed in the same procedure. An onion reference is transferred from the temporary source node to an upper node in the tree structure, and a search agent is transferred from the virtual search source node to an upper node, so that a search by a search agent is performed at any node in the tree structure. Onion reference hits. As a result, an anonymous communication path between the transmission source node and the search source node is generated.

  FIG. 18 is a diagram illustrating an example of a data structure of a data packet. The data packet 530 includes a message flag 531, a destination (To) 532, a transmission source (From) 533, a destination onion 534, a return & backtrack onion 535, and a payload 536.

  A message flag 531 indicates the type of packet. In the case of the data packet 530, information indicating a data communication packet (normal packet) is set.

In the destination 532, the destination of the data packet 530 is set. The destination is the public ID of the communication partner node.
In the transmission source 533, an anonymous ID of a node serving as a packet transmission source is set. This anonymous ID is different from that used when searching for an anonymous communication path.

  The destination onion 534 is information indicating a route to the destination. This is generated based on the acquired anonymous communication path information. The destination onion 534 is obtained by encrypting route information with the public key of each node so that only the next node can be recognized at each node on the anonymous communication path.

  The return & backtrack onion 535 is route information indicating a return route and a route when backtrack processing is performed. The backtrack process is a process for transmitting a packet via another route when communication on a planned route is not possible.

  The payload 536 is actual data including data obtained by encrypting the message to be transferred with the public key of the receiving node. For example, the payload 536 includes an onion reference and a search agent.

Such a data packet is transmitted and received between the transmission source node and the search source node via the anonymous communication path. Thereby, the anonymity of communication is maintained.
If such a function is used, an electronic bulletin board system with high anonymity can be provided.

  FIG. 19 is a diagram illustrating a configuration example of a highly anonymous electronic bulletin board. In this example, it is assumed that a contributor to the bulletin board uses the node 601 and a searcher of the bulletin board uses the node 602. The nodes 611 to 617 form a tree structure, and these nodes 611 to 617 provide a function as an electronic bulletin board for performing information disclosure. In addition, the node 601 has selected the node 616 as the temporary disclosure source node. Further, the node 602 selects the node 617 as the temporary search source node.

  Note that the node ID of the node 601 is “A”, the node ID of the node 602 is “B”, the node ID of the node 611 is “P”, the node ID of the node 612 is “S”, and the node ID of the node 613 is “H”. ”, Node ID of node 614 is“ T ”, node ID of node 615 is“ R ”, node ID of node 616 is“ X ”, node ID of node 617 is“ Y ”, and node ID of node 621 is“ K ” ”, The node ID of the node 622 is“ L ”, the node ID of the node 623 is“ G ”, the node ID of the node 624 is“ E ”, the node ID of the node 625 is“ W ”, and the node ID of the node 626 is“ V ” "

  A contributor to the bulletin board transmits an onion reference from the node 601 to the node 616 by anonymous communication using onion routing technology. The onion reference is sequentially transferred from the node 616 to the parent node on the tree structure. Each node 616, 614, 613, 612, 611 that has transferred the onion reference caches the onion reference.

  The onion reference includes return route information to the node 601 as well as metadata (keywords, creation date, etc.) of information published by the poster. As the onion reference is released in this manner, the information posted by the poster is released.

  A searcher for information in the bulletin board transmits a search agent from the node 602 to the node 617 by anonymous communication using onion routing technology. The search agent is sequentially transferred from the node 617 to the parent node on the tree structure. Each node 617, 615, 613, 612, 611 that has transferred the search agent caches the search agent.

  The search agent includes a search condition based on a search keyword specified by the searcher. Onion references that match the search conditions in the search agent are searched in the node where the search agent is cached. If the information posted by the user of the node 601 matches the search condition, the search hits at the node 613. At this time, by connecting the return onion of the onion reference cached in the node 613 and the return onion of the search agent cached in the node 613, an anonymous communication path between the node 601 and the node 602 can be generated.

FIG. 20 is a diagram illustrating information cached by each node. In the following description, the return onion route is indicated by an array of node IDs of the nodes on the return route.
One of the information cached by the node 611 is the anonymous ID of the node itself, the public information posted by the node ID “A” (onion reference), and the return onion between PSHHTXA. The node 611 also caches the node's own anonymous ID, the search agent with the node ID “B”, and the return onion between PSH-R-Y-B.

  One of the information cached by the node 612 is the anonymous ID of the node itself, the public information (onion reference) posted by the node ID “A”, and the return onion between SH-X-A. The node 612 also caches the node's own anonymous ID, the search agent with the node ID “B”, and the return onion between S—H—R—Y—B.

  One of the information cached by the node 613 is the node's own anonymous ID, public information posted by the node ID “A” (onion reference), and return onion between H-T-X-A. The node 613 also caches the node's own anonymous ID, the search agent of the node ID “B”, and the return onion between HR-Y-B.

  The information cached by the node 614 is the anonymous ID of the node itself, the public information (onion reference) posted by the node ID “A”, and the return onion between TXA. The information cached by the node 615 is the anonymous ID of the node itself, the search agent of the node ID “B”, and the return onion between RYB.

  The information cached by the node 616 is the anonymous ID of the node itself, the public information (onion reference) posted by the node ID “A”, and the return onion between X-A. The information cached by the node 617 is the node's own anonymous ID, the search agent of the node ID “B”, and the return onion between YB.

  FIG. 21 is a diagram illustrating the generated anonymous communication path. The anonymous communication path is created at node 613 by connecting the return onion on the onion reference side and the return onion on the search agent side.

  Here, the route between the node 601 and the node 616 is via the node 622. This is the route actually passed when the onion reference is transmitted to the node 616. In other words, the return onion is created by adding information on the node that transmitted the packet while transmitting the packet, so the route actually taken at the time of transmission becomes the return route.

  Similarly, the route between the node 602 and the node 617 is via the node 626. This is the route actually taken when the search agent is transmitted to the node 617.

  Communication can be performed between the node 601 and the node 602 via such an anonymous communication path. That is, the contents of information published by the node 601 (stored in the node 601) can be referenced from the node 602.

By the way, an anonymous communication path that directly connects the node 622 and the node 626 can be generated.
FIG. 22 is a diagram illustrating an example of generating an anonymous communication path with a shortened path length. In this example, when the onion reference is transferred from the temporary transmission source node to the parent node, relay node information including the node ID, IP address, port number, and the like of the adjacent node that has transmitted the onion reference is simultaneously transmitted. Each node that receives the onion reference also caches the relay node information together with the onion reference.

  In the example shown in the state ST11, the onion reference is transmitted via the node 622 having the node ID “L”. Therefore, the relay node information such as the node ID “L” of the node 622 and the IP address is set as a cache target. When a search hit occurs, the search agent transmits relay node information to the search source node together with the onion reference and various return onions.

  When the search source node 602 acquires the information of the node 622 and performs anonymous communication with the node 601, the anonymous communication such as transferring a packet from any of the nodes 624 to 626 to the node 622. A path can be generated. That is, even if the node relayed when transmitting the search agent is the node 626, an anonymous communication path via the node 624 or the node 625 can be generated.

At this time, it is necessary to notify the nodes 624 to 625 of the node ID, IP address, and port number of the node 622.
As shown in state ST12, if an anonymous communication path via the node 625 is generated and a packet is transmitted to the node 601 via the anonymous communication path, one communication path through which the packet actually passes Is determined as an anonymous communication path between the node 601 and the node 602. In this example, an anonymous communication path is generated such that the node 625 and the node 622 directly deliver a packet.

  In this way, it is possible to generate an anonymous communication path in which the space between the temporary transmission source node and the temporary search source node is omitted. As a result, anonymous communication does not have to go through the upper node of the tree structure, and the load on the upper node can be reduced.

  As a technique for performing anonymous communication, there is a technique in which route information (route information for each node) notified to each node on the anonymous route is encrypted with the public key of the corresponding node and included in the packet. The node-specific route information is stored in a block corresponding to each node. The node-specific route information includes identification information of a node adjacent to the corresponding node (a node adjacent in the transmission direction and a node adjacent in the return direction) and a block position to be decoded by the adjacent node.

  Furthermore, when a transmission source transmits a packet, it is included in an information (block specification) packet that specifies the position of a block to be decoded by an adjacent node. The relay node receiving this packet recognizes the adjacent node and the position of the block to be decoded by the adjacent node by decoding the block indicated by the block designation. Therefore, the relay node changes the block designation content to the position of the block corresponding to the adjacent node, and then forwards the packet to the adjacent node. Thereafter, the packet is similarly relayed.

  If such packet transfer is performed, each relay node can recognize only a node adjacent to itself among anonymous routes. Therefore, packet transfer with the transmission source and destination hidden is possible. Hereinafter, such an anonymous communication method is referred to as grape routing.

If such a grape routing technique is used, an anonymous communication path in which the space between the temporary transmission source node and the temporary search source node is omitted can be generated.
FIG. 23 is a diagram illustrating a structure example of a data packet when performing grape routing. The data packet 540 for grape routing includes a message flag 541, a destination (To) 542, a transmission source (From) 543, a block designation 544, a grape route 545, and a payload 546.

A message flag 541 indicates the type of packet. In the case of the data packet 540, information indicating that it is a data packet for grape routing is set.
In the destination 542, the destination of the data packet 540 is set. The destination is the anonymous ID of the transmission source node set in the transmission source 513 of the route search packet 510.

In the transmission source 543, the public ID (public ID) of the temporary transmission source node is set.
In the block designation 544, the position of the block in the grape root to be decoded by the node that has received the packet is set.

  The grape route 545 stores information to be notified to each node on the anonymous communication path in blocks. For example, each block is encrypted with the public key of the corresponding node. The node that has received the data packet 540 can recognize the block to be decoded by the block designation 544.

  The decoded block includes, for example, the node ID of the next adjacent node on the anonymous communication path, the block position decoded by the next adjacent node, and the like. Therefore, the node that has received the data packet 540 transfers the data packet 540 to the adjacent node corresponding to the node ID included in the decoded block. At this time, the content of the block designation 544 is replaced with the block position decoded by the next adjacent node.

The payload 546 is actual data including data obtained by encrypting a message to be transferred with the public key of the receiving node.
FIG. 24 is a diagram showing the contents of the cache when performing grape routing. When performing grape routing, each node that caches an onion reference and a search agent also caches information about the grape route and adjacent nodes at the same time.

  In the example of FIG. 24, each node above the temporary transmission source node 616 includes the node's own temporary identifier, the onion reference posted by the node 601 with the node ID “A”, the node 616 with the node ID “X”, and the node Table information such as an anonymous grape route with the node 601 with ID “A”, node IDs and IP addresses of the nodes 616, 621 to 623 is cached. The anonymous grape root to be cached also includes information indicating the position of the block to be decoded by the nodes 616, 621 to 623 in the grape root.

  Further, each node higher than the temporary search source node 617 includes a temporary identifier of the node itself, a search agent having a node ID “B”, a node 617 having a node ID “Y”, and a node 602 having a node ID “B”. Table information such as the anonymous grape route, node IDs and IP addresses of the nodes 617 and 624 to 626 is cached. Note that the anonymous grape root to be cached also includes information indicating the position of the block to be decoded by the nodes 617 and 624 to 626 in the grape root.

  If the search hits the node 613 with the node ID “H”, the node 613 transmits the search result to the temporary search source node 617. At this time, it can be directly transmitted without going through the node 615.

  FIG. 25 is a diagram illustrating a state of the search result notification. The node 613 generates a data packet for transmitting a search result from the node 613 to the node 602 based on the grape route between the node 602 and the node 617. The generated data packet is transmitted to the node 617. The data packet is transferred by grape routing via the anonymous communication path from the node 617 to the node 602.

  In addition to the onion reference, the search result includes information cached with the onion reference and the search agent. That is, table information such as a grape route between the node 601 and the node 616, a grape route between the node 602 and the node 617, and node IDs and IP addresses of the nodes 616, 617, and 621 to 626 are included in the search results. .

  Since the node 613 recognizes the node IDs and IP addresses of the nodes 624 to 626 and the position of the block to be decoded in the grape route, a search result is obtained for any of the nodes 624 to 626. It is also possible to transmit a data packet indicating That is, the search result can be transmitted through a route that does not pass through the node 617 (indicated by a dashed arrow in the figure).

  When the node 602 receives the search result, the node 602 returns a response indicating that the search result has been received. At this time, grape routing is always performed in the anonymous communication path via the node 617. That is, the nodes 624 to 626 can recognize only the information of the node 617 that is an adjacent node in the grape routing. Therefore, a packet addressed to the node 613 from the node 602 is passed to the node 617 via any of the nodes 624 to 626. Then, the packet is passed to the node 613 via the node 617.

  Note that there are a plurality of routes between the node 602 and the node 617 because of grape routing. Similarly, a plurality of routes exist between the node 601 and the node 616 because of the grape routing.

  The node 602 that has received the search result generates a grape route up to the node 601 based on the information included in the search result. Note that the node 602 receives a grape route for transmitting a packet from the node 616 to the node 601 as a search result, and also receives an IP address, a node ID, and the like of the route 616. Therefore, when a packet is transmitted from the node 602 to the node 601, the packet is transmitted through an anonymous communication path via the node 616.

  FIG. 26 is a diagram illustrating an anonymous communication path between a search source node and a disclosure source node. The search source node 602 creates an anonymous grape route based on table information such as node IDs and IP addresses of the nodes 616, 621 to 623. For example, the node 602 has an anonymous grape route between the node 616 and the node 601, a route from the node 616 to the nodes 624 to 626 (indicated by a one-dot chain line in the figure), and a direction to return to the nodes 621 to 623. A route (indicated by a broken line in the figure) of the nodes 624 to 626 is created. If an anonymous grape route between the nodes 624 to 626 and the node 602 is added to the created route, an anonymous grape route from the node 601 to the node 602 is created.

  The anonymous grape route creation from the nodes 624 to 626 to the node 602 by the node 602 can be performed when the search result is received. Further, an anonymous grape route for the node 602 from the nodes 624 to 626 can be sent in advance to the search agent and received together with the search result.

  At this time, packet information can be transferred from the nodes 624 to 626 to the nodes 621 to 623 by notifying the nodes 624 to 626 of the table information such as the node IDs and IP addresses of the nodes 621 to 623.

  As a result, bidirectional communication is possible between the nodes 624 to 626 and the node 616. Although packets can be transferred from the nodes 624 to 626 to the nodes 621 to 623, packet transfer in the reverse direction is not possible. This is because the anonymous grape route between the node 601 and the node 621 only shows transmission to the adjacent node 616 with respect to the nodes 624 to 626. Therefore, when performing anonymous communication from the node 601 to the node 602, it is necessary to go through the node 616.

  By the way, in the grape routing, as a countermeasure against fraud due to collusion of nodes, it is possible to perform a process of “discarding things other than a set of nodes that should receive data”. For example, the nodes 621 to 623 discard packets from the adjacent nodes on the communication path from the node 601 and nodes other than the node 616. Similarly, the nodes 624 to 626 discard packets from nodes other than the adjacent node on the communication path from the node 602 and the node 616.

  FIG. 27 is a diagram illustrating an example of an anonymous communication path when node collusion is prevented. As shown in FIG. 27, the communication path between the node 601 and the node 602 is always performed via the node 616. Thereby, the administrator of the nodes 621 to 623 and the administrator of the nodes 624 to 626 collide, and the act of analyzing the anonymous communication path between the node 601 and the node 602 can be prevented.

  In addition, the anonymity and security level of grape routing can be reduced, and availability can be prioritized. In this case, the grape immediately before the cache start node (temporary disclosure source node or temporary search source node) (a block in which information related to routing addressed to the immediately preceding node is registered) can be rewritten without encryption. Note that availability is the ability to continue operation without bringing down communication.

  FIG. 28 is a diagram illustrating an example of an anonymous communication path when importance is placed on availability. In this way, by making the blocks corresponding to the nodes 621 to 626 in the grape route plaintext, the contents can be rewritten as appropriate. As a result, mutual packet exchange between the nodes 621 to 623 and the nodes 624 to 626 becomes possible. That is, the route between the node 601 and the node 602 can have diversity. If the route is available, communication is possible via another route even if one node on the communication path stops.

According to the embodiment as described above, the following effects can be obtained.
By defining the relationship between the whole or partial nodes of the P2P network in a tree structure, it is possible to efficiently search all cases of information on the P2P network. At this time, the transmitted information (onion reference and search agent) is cached on the P2P network. Moreover, the onion reference and the search agent are associated with the transmission source via the anonymous communication path. Therefore, anonymity is not impaired by having a tree structure.

  Also, a temporary publishing source node and a temporary search source node are set, anonymous communication is performed between the publishing source node and the temporary publishing source node, and anonymous communication is performed between the search source node and the temporary search source node. . Thereby, even if anonymity is not sufficient in the above tree structure of the temporary public source node and the temporary search source node, the anonymity between the public source node and the search source node can be maintained.

  In addition, since onion routing is used for anonymous communication, keys for decrypting encrypted route information are distributed over an unspecified number. Therefore, the vulnerability of anonymization due to the intensive concentration of keys can be eliminated.

  In addition, when a search is hit, information related to the anonymous communication path to the node from which the public information is transmitted is transmitted to the node from which the search is made. It becomes possible to communicate.

  The above processing functions can be realized by a computer. In that case, an information search program describing the processing content of the function that each node should have is provided. The processing function is realized on the computer by executing the information retrieval program on the computer. The information retrieval program describing the processing contents can be recorded on a computer-readable recording medium. Examples of the computer-readable recording medium include a magnetic recording device, an optical disk, a magneto-optical recording medium, and a semiconductor memory. Examples of the magnetic recording device include a hard disk device (HDD), a flexible disk (FD), and a magnetic tape. Examples of the optical disc include a DVD (Digital Versatile Disc), a DVD-RAM (Random Access Memory), a CD-ROM (Compact Disc Read Only Memory), and a CD-R (Recordable) / RW (ReWritable). Magneto-optical recording media include MO (Magneto-Optical disk).

  When distributing an information search program, for example, a portable recording medium such as a DVD or a CD-ROM in which the information search program is recorded is sold. It is also possible to store the information retrieval program in a storage device of the server computer and transfer the information retrieval program from the server computer to another computer via a network.

  A computer that executes an information search program stores, for example, an information search program recorded on a portable recording medium or an information search program transferred from a server computer in its own storage device. Then, the computer reads the information search program from its own storage device and executes processing according to the information search program. The computer can also read the information search program directly from the portable recording medium and execute processing according to the information search program. Further, each time the information search program is transferred from the server computer, the computer can sequentially execute processing according to the received information search program.

(Supplementary Note 1) In an information search method for searching information published on a peer-to-peer network,
When the public information storage unit of the information search device connected to the network receives an information disclosure request including public information from another device, the public information storage unit stores the public information,
The relationship between devices in the network is defined in a tree structure, and the information disclosure request transfer means of the information search device transfers the information disclosure request to the parent device in the tree structure,
When the search condition storage means of the information search apparatus receives an information search request including a search request from another apparatus, the search condition storage means stores the search condition in the search condition storage means,
The information search request transfer means of the information search device transfers the information search request to the parent device in the tree structure,
The search means of the information search device searches the public information stored in the public information storage means based on the search conditions stored in the search condition storage means,
The search result notifying unit of the information search device transmits a search result to a search source device that is a transmission source of the information search request when the public information matches the search condition.
An information search method characterized by that.

(Supplementary Note 2) The information disclosure request includes communication path information to a disclosure source device that is a transmission source of the information disclosure request, and when the disclosure information storage unit receives the information disclosure request, Storing the communication path information in the public information storage means;
The search result notifying means, when the public information matches the search condition, transmits the public information and the communication path information to the public source device to the search source device;
The information search method according to supplementary note 1, wherein:

(Additional remark 3) The publication source apparatus which is the transmission source of the information disclosure request selects at least one information retrieval apparatus from among the plurality of information retrieval apparatuses constituting the tree structure in response to an information disclosure instruction. And transmitting the information disclosure request to the selected information retrieval device by anonymous communication.
The information search method according to supplementary note 1, wherein:

(Supplementary Note 4) A search source device that is a transmission source of the information search request selects at least one information search device from among the plurality of information search devices constituting the tree structure in response to an information search instruction. And transmitting the information search request including a search condition to the selected information search device by anonymous communication.
The information search method according to supplementary note 1, wherein:

  (Supplementary Note 5) When the new search condition is stored in the search condition storage unit, the search unit searches the public information storage unit for the public information that matches the newly stored search condition. The information search method according to supplementary note 1, wherein:

  (Additional remark 6) The search by the said search means, when the said new public information is memorize | stored in the said public information storage means, the said newly memorized public information has already been memorize | stored in the said search condition memory | storage means The information search method according to appendix 1, wherein it is determined whether or not the search condition is met.

  (Supplementary note 7) The information search method according to supplementary note 1, wherein the public information storage means deletes the public information when the public information stored in the public information storage means satisfies a predetermined condition. .

  (Supplementary note 8) The information search method according to supplementary note 1, wherein the search condition storage unit deletes the search condition when the search condition stored in the search condition storage unit satisfies a predetermined condition. .

(Supplementary Note 9) In an information search method for searching information published on a peer-to-peer network,
The disclosure source device that is the transmission source of the information disclosure request selects at least one information retrieval device from among a plurality of information retrieval devices in the network in response to an information disclosure instruction, and the selected information retrieval Send the information disclosure request to the device by anonymous communication,
The search source device that is the transmission source of the information search request selects at least one information search device from among the plurality of information search devices in the network in response to an information search instruction, and the selected information Sending the information search request including the search condition to the search device by anonymous communication,
In each of the information search devices constituting the network,
When the public information storage means receives an information disclosure request including public information from another device, the public information storage means stores the public information in the public information storage means,
An information disclosure request transfer means transfers the information disclosure request to another adjacent information retrieval device,
When the search condition storage means receives an information search request including a search request from another device, the search condition storage means stores the search condition in the search condition storage means,
The information search request transfer means transfers the information search request to another adjacent information search device,
The search means searches the public information stored in the public information storage means based on the search conditions stored in the search condition storage means,
When the search result notifying means matches the search condition with the public information, the public information is transmitted to the search source device by anonymous communication.
An information search method characterized by that.

(Supplementary Note 10) In an information search apparatus for searching information published on a peer-to-peer network,
When receiving an information disclosure request including public information from another device, public information storage means for storing the public information in a public information storage means;
A relationship between devices in the network is defined in a tree structure, and information disclosure request transfer means for transferring the information disclosure request to a parent device in the tree structure;
When an information search request including a search request is received from another device, search condition storage means for storing the search condition in the search condition storage means;
Information search request transfer means for transferring the information search request to the parent device in the tree structure;
Search means for searching the public information stored in the public information storage means based on the search conditions stored in the search condition storage means;
Search result notifying means for transmitting a search result to a search source device that is a transmission source of the information search request when the public information matches the search condition;
An information retrieval apparatus comprising:

(Supplementary Note 11) In an information retrieval program for retrieving information published on a peer-to-peer network,
On the computer,
When the public information storage means receives an information disclosure request including public information from another device, the public information storage means stores the public information in the public information storage means,
A relationship between devices in the network is defined in a tree structure, and an information disclosure request transfer unit transfers the information disclosure request to a parent device in the tree structure,
When the search condition storage means receives an information search request including a search request from another device, the search condition storage means stores the search condition in the search condition storage means,
An information search request transfer means transfers the information search request to the parent device in the tree structure;
The search means searches the public information stored in the public information storage means based on the search conditions stored in the search condition storage means,
The search result notifying means transmits a search result to a search source device that is a transmission source of the information search request when the public information matches the search condition.
An information search program characterized by causing processing to be executed.

(Supplementary Note 12) In a computer-readable recording medium in which an information search program for searching information published on a peer-to-peer network is recorded,
On the computer,
When the public information storage means receives an information disclosure request including public information from another device, the public information storage means stores the public information in the public information storage means,
A relationship between devices in the network is defined in a tree structure, and an information disclosure request transfer unit transfers the information disclosure request to a parent device in the tree structure,
When the search condition storage means receives an information search request including a search request from another device, the search condition storage means stores the search condition in the search condition storage means,
An information search request transfer means transfers the information search request to the parent device in the tree structure;
The search means searches the public information stored in the public information storage means based on the search conditions stored in the search condition storage means,
The search result notifying means transmits a search result to a search source device that is a transmission source of the information search request when the public information matches the search condition.
A computer-readable recording medium having recorded thereon an information search program characterized in that processing is executed.

It is a conceptual diagram of the invention applied to embodiment. It is a figure which shows the network structural example of this Embodiment. It is a figure which shows the hardware structural example of the node used for embodiment of this invention. It is a conceptual diagram which shows the information search in embodiment of this invention. It is a figure which shows the tree structure of a network. It is a conceptual diagram of the information search using a tree structure. It is a block diagram which shows the processing function in a node. It is a figure which shows the example of a data structure of a node management table. It is a figure which shows the process at the time of information disclosure. It is a figure which shows the process at the time of an information search. It is a figure which shows the process at the time of a search hit. It is a figure which shows the state transition of an anonymous communication path formation process. It is a flowchart which shows the procedure of a route search start process. It is a figure which shows the data structure example of a route search packet. It is a flowchart which shows the procedure of the reception process of a route search packet. It is a figure which shows the example of a data structure of a route notification packet. It is a flowchart which shows a route notification packet reception process. It is a figure which shows the data structure example of a data packet. It is a figure which shows the structural example of an electronic bulletin board with high anonymity. It is a figure which shows the information which each node caches. It is a figure which shows the produced | generated anonymous communication path. It is a figure which shows the example of anonymous communication path | route production | generation which shortened path length. It is a figure which shows the structural example of the data packet at the time of performing grape routing. It is a figure which shows the cache content when performing grape routing. It is a figure which shows the mode of a search result notification. It is a figure which shows the anonymous communication path between a search origin node and a transmission origin node. It is a figure which shows the example of the anonymous communication path at the time of preventing collusion of a node. It is a figure which shows the example of the anonymous communication path when placing importance on availability.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Information retrieval apparatus 1a Public information storage means 1b Public information storage means 1c Information disclosure request transfer means 1d Search condition storage means 1e Search condition storage means 1f Information search request transfer means 1g Search means 1h Search result notification means 2 Publication source apparatus 3 Search Original device 4,5 Child device 6 Parent device 7 Information disclosure request 8 Information search request

Claims (9)

In an information search method for searching information published on a peer-to-peer network,
Anonymous communication in which the public information storage means of the information search device connected to the network conceals at least part of the communication path between the public information from another device and the public source device that is the transmission source of the public information When receiving an information disclosure request including the first anonymous channel information for performing , the public information storage means stores the public information and the first anonymous channel information ,
The relationship between devices in the network is defined in a tree structure, and the information disclosure request transfer means of the information search device transfers the information disclosure request to the parent device in the tree structure,
The search condition storage means of the information search device includes a search condition from another device and second anonymous channel information for performing the anonymous communication between the search source device that is a transmission source of the search condition. When receiving an information search request including, the search condition storage means stores the search condition and the second anonymous channel information ,
The information search request transfer means of the information search device transfers the information search request to the parent device in the tree structure,
The search means of the information search device searches the public information stored in the public information storage means based on the search conditions stored in the search condition storage means,
When the search result notification means of the information search device matches the search condition, the anonymous information channel is connected to the first anonymous channel information by connecting the first anonymous channel information to the second anonymous channel information. enabling the anonymous communication between the search source device and said public source device and then transmits the search result to the pre-dangerous search source apparatus,
An information search method characterized by that. The publication source device selects at least one information retrieval device from among the plurality of information retrieval devices constituting the tree structure in response to an information disclosure instruction, and the selected information retrieval device Send information disclosure request by anonymous communication,
The information search method according to claim 1, wherein: The information retrieval is the sender of the request the search source device, in response to a search instruction information, selecting at least one of said information retrieval device from a plurality of said information retrieval device constituting the tree structure, selection The information search request including the search condition is transmitted to the information search device by anonymous communication.
The information search method according to claim 1, wherein: When the new search condition is stored in the search condition storage unit, the search unit searches the public information storage unit for the public information that matches the newly stored search condition. The information search method according to claim 1. When the new public information is stored in the public information storage unit, the newly stored public information matches the search condition already stored in the search condition storage unit. The information retrieval method according to claim 1, wherein it is determined whether or not to perform . 2. The information search method according to claim 1 , wherein the public information storage means deletes the public information when the public information stored in the public information storage means satisfies a predetermined condition .   In an information search method for searching information published on a peer-to-peer network,
  The publishing source device that is the transmission source of the information publishing request including the publishing information selects at least one information retrieval device from the plurality of information retrieval devices in the network according to the information disclosure instruction, and selects Sending the information disclosure request to the information search device by anonymous communication that conceals at least a part of the communication path,
  The information retrieval device selected by the publishing source device includes first anonymous channel information for performing the anonymous communication to the publishing source device that is the transmission source of the information disclosure request, and the first anonymous channel. Including the relay node information indicating the device capable of anonymous communication with the publishing device using information included in the information disclosure request,
  The search source device that is the transmission source of the information search request selects at least one information search device from among the plurality of information search devices in the network in response to an information search instruction, and the selected information search Sending the information search request including a search condition to the device by the anonymous communication,
  The relationship between the information search devices in the network is defined in a tree structure, and in each of the information search devices constituting the network,
  When the public information storage means receives the information disclosure request from another device, the public information storage means stores the public information, the first anonymous channel information, and the relay node information;
  An information disclosure request transfer means transfers the information disclosure request to a parent information search device in the tree structure,
  The search condition storage means sends an information search request including a search condition from another device and second anonymous channel information for performing the anonymous communication between the search source device that is the transmission source of the search condition. If received, the search condition storage means stores the search condition and the second anonymous channel information,
  An information search request transfer means transfers the information search request to a parent information search device in the tree structure,
  The search means searches the public information stored in the public information storage means based on the search conditions stored in the search condition storage means,
  When the public information matches the search condition, the search result notifying means sends a search result including the public information, the first anonymous communication path information, and relay node information to the search source device. Transmitted by the anonymous communication based on the anonymous communication path information,
  The search source device that has received the search result establishes an anonymous communication path with the relay node using the device indicated by the relay node information as a relay node, and the publication source device via the relay node The anonymous communication with
  An information search method characterized by that.   In an information retrieval apparatus for retrieving information published on a peer-to-peer network,
  Information disclosure including public information from another device and first anonymous communication channel information for performing anonymous communication in which at least a part of the communication path is hidden between the public device that is the transmission source of the public information When receiving the request, the public information storage means for storing the public information and the first anonymous communication path information in the public information storage means;
  A relationship between devices in the network is defined in a tree structure, and information disclosure request transfer means for transferring the information disclosure request to a parent device in the tree structure;
  When an information search request including a search condition and second anonymous communication path information for performing the anonymous communication between a search source device that is a transmission source of the search condition is received from another device, the search condition Search condition storage means for storing the search condition and the second anonymous communication path information in a storage means;
  Information search request transfer means for transferring the information search request to the parent device in the tree structure;
  Search means for searching the public information stored in the public information storage means based on the search conditions stored in the search condition storage means;
  When the public information matches the search condition, an anonymous communication path between the first anonymous communication path information and the second anonymous communication path information is connected between the search source apparatus and the publication source apparatus. Search result notifying means for enabling the anonymous communication and transmitting a search result to the search source device;
  An information retrieval apparatus comprising:   In an information retrieval program for retrieving information published on a peer-to-peer network,
  On the computer,
  A first anonymous communication path for performing anonymous communication in which the public information storage means conceals at least a part of the communication path between the public information from another apparatus and the public source apparatus that is the transmission source of the public information. If an information disclosure request including information is received, the disclosure information is stored with respect to the disclosure information storage means and the first anonymous channel information,
  A relationship between devices in the network is defined in a tree structure, and an information disclosure request transfer unit transfers the information disclosure request to a parent device in the tree structure,
  The search condition storage means sends an information search request including a search condition from another device and second anonymous channel information for performing the anonymous communication between the search source device that is the transmission source of the search condition. If received, the search condition storage means stores the search condition and the second anonymous channel information,
  An information search request transfer means transfers the information search request to the parent device in the tree structure;
  The search means searches the public information stored in the public information storage means based on the search conditions stored in the search condition storage means,
  When the search information notifying means matches the search information with the public information, the search source device and the second anonymous channel information are connected by connecting the first anonymous channel information and the second anonymous channel information. Enabling the anonymous communication with the publishing source device and transmitting the search result to the searching source device;
  An information search program characterized by causing processing to be executed.

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