JP2008028576A - Vpn server hosting system, vpn build up method, and computer program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To flexibly and simply build up a VPN (Virtual Private Network) for a member arbitrarily selected from a plurality of clients. <P>SOLUTION: By using: a member list for members arbitrarily selected from clients receiving a digital certificate; and a public key corresponding to private keys used for the issuance of the digital certificate, as an argument of a hash function, a hash value is calculated. The hash value is associated with an identification (ID) of a VPN server process. When a client requests connection to a generated VPN server process, his/her digital certificate is verified. The connection is permitted for the client, only if the client is contained in the members. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a VPN server hosting system that operates a VPN server process for connecting a plurality of information terminals through a virtual dedicated line, a VPN construction method for constructing a VPN using the VPN server hosting system, and a computer for constructing a VPN Regarding the program.

  In recent years, with the background of the ever-expanding Internet connection environment and the increase in network-compatible products in home appliances such as AV equipment, the general households are also away from home for communication devices. The demand for remote access from is increasing. In addition, files are shared among a plurality of users via the Internet, and Internet-connected games are also enjoyed. As one of the methods for realizing these services, a VPN (Virtual Private Network), which is a virtual dedicated line, is constructed for each user, thereby providing a safe network environment. .

  Here, the VPN is a virtual closed network configured by connecting two points on the Internet using encryption technology, and computers in remote locations are as if they are one LAN (Local Area). As in the case of being connected to (Network), it is possible to prevent eavesdropping by a third party and to communicate with each other (for example, see Non-Patent Document 1). Specifically, a VPN server that relays VPN traffic is installed, and the network that is isolated from a third party is realized by the server mediating communication between two authorized computers Is done.

Regarding VPN, the applicant has already applied for a patent application of Japanese Patent Application No. 2005-249137. The VPN technology proposed in this application is as follows. That is, a network is configured by a VPN server hosting system that includes a plurality of host servers and operates a VPN server process, an in-home relay device and an in-home communication device installed in the house, and a mobile terminal that is away from home. Then, the hash value H (pk) calculated from the public key pk of the home relay device is made to correspond to the ID of the VPN server process, and this VPN server process is assigned to a specific host server by using a distributed hash table to be operated. . Clients (home relay device and mobile terminal) request a connection to the VPN server process by presenting a client certificate issued by the home relay device. When the certificate is authenticated by the public key pk and it is proved that the client possesses the client private key corresponding to the certificate, the VPN server process is connected to the client and the VPN is constructed. . This enables communication between the mobile terminal and the home communication device via the VPN.
“SoftEther Virtual Ethernet System”, [online], SoftEther Corporation, [searched July 3, 2006], Internet, <URL: http://www.softether.com/jp/>

In the above-described VPN server hosting system, when the home relay device generates a public key and private key pair and issues a client certificate to the client using the private key, the client having the client certificate A VPN server process that can only be connected to can be created. However, for example, when only a part of a plurality of clients are members and an attempt is made to construct a VPN dedicated to these members independently of the original VPN, generation of a public / private key pair and a client certificate are again performed. There is a problem that the process becomes complicated because the procedure of issuing and distributing is required. Further, for example, client a1 from device A is issued a client certificate _{C A,} a2, a3, client b1, b2, b3 issued a client certificate _{C B} from the apparatus B, and the client certificate _{C CA} from device CA When issued clients u1, u2, and u3 exist, a group is formed with clients a1, b1, b2, and u1, and a VPN that can be connected only to members of this group is newly created. The client certificate must be reissued. For this reason, it is difficult to easily use the VPN when sharing files with a plurality of users.

  The present invention has been made in view of these points, and an object of the present invention is to provide a VPN server hosting system that can flexibly and easily construct a VPN for members arbitrarily selected from a plurality of clients. Is to provide. In addition, a VPN construction method for constructing a VPN using the VPN server hosting system and a computer program for constructing the VPN are provided.

  The present invention has been made to solve the above-mentioned problems, and the invention according to claim 1 executes a VPN server process for connecting a plurality of information terminals with a virtual dedicated line. A VPN server hosting system comprising a plurality of host servers, which generates a public key and a private key pair and obtains a digital certificate from a certificate issuing device that issues a digital certificate signed with the private key Among the information terminals, a plurality of arbitrarily designated information terminals are members, and a hash value of VPN server process specifying information including a public key of the certificate issuing device and a member list for specifying the members is used as an ID. VPN server generation means for generating a VPN server process in the predetermined host server, and the information terminal specifies the VPN server process When the information terminal and the issued digital certificate are presented to request connection to the VPN server process, the information terminal that is the owner of the digital certificate specified by the presented digital certificate is The information terminal is included only when it is included in the member list of the presented VPN server process identification information and the presented digital certificate is verified by the public key of the presented VPN server process identification information VPN server hosting means for permitting connection to a VPN server process whose ID is the hash value of the presented VPN server process identification information.

  In this invention, a member list of members arbitrarily selected from an information terminal that has issued a digital certificate and a public key corresponding to the private key used for issuing the digital certificate are used as arguments of the hash function. A hash value is calculated, and this hash value is made to correspond to the ID of the VPN server process. Then, when the information terminal requests connection to the VPN server process, the digital certificate is verified, and connection is permitted only when the information terminal is included in the member. Therefore, it is not necessary to issue a new digital certificate to the members who created the group, and the VPN can be constructed and operated flexibly and easily.

  The invention described in claim 2 is the VPN server hosting system according to claim 1, wherein at least one information terminal included in the member has a digital certificate issued to another information terminal. And the VPN server process specifying information is used for all the certificates when the digital certificate issued from a certificate issuing device different from the certificate issuing device that issued the digital certificate is owned. It is characterized by comprising each public key of the issuing device and a member list for specifying the member.

  According to the present invention, even when a plurality of certificate issuing devices exist and issue different digital certificates to information terminals, it is possible to construct a VPN including information terminals having different digital certificates as members. it can.

  The invention according to claim 3 is the VPN server hosting system according to claim 1 or 2, wherein each of the host servers has a distributed hash table defining a range of the hash values managed by the host server. The VPN server generating means selects a host server corresponding to the hash value of the VPN server process specifying information according to the distributed hash table, and generates a VPN server process in the selected host server It is characterized by.

  According to a fourth aspect of the present invention, in the VPN server hosting system according to any one of the first to third aspects of the present invention, an information terminal that is permitted to connect to a VPN server process by the VPN server connection means. In communication between the VPN server process and a session key generating means for generating a first session key shared by the plurality of information terminals, and a first shared only between the first session key and the information terminals. A packet authentication code is added using the second session key, the header is encrypted using the first session key, and the payload is encrypted using the second session key. Packet analysis means for performing message authentication and decryption of the header using the first session key, Characterized in that it comprises the al.

  The invention described in claim 5 causes a VPN server process to connect a plurality of information terminals via a virtual dedicated line to any one of the host servers in a server system composed of one or a plurality of host servers. A VPN construction method for constructing a VPN by generating a digital certificate from a certificate issuing device that generates a public key and a private key pair and issues a digital certificate signed with the private key. A VPN server whose ID is a hash value of VPN server process specifying information including a public key of the certificate issuing device and a member list for specifying the member, with a plurality of arbitrarily specified information terminals among the terminals as members. Generating a process in the predetermined host server; and When the issued digital certificate is presented and a connection to the VPN server process is requested, the information terminal that is the owner of the digital certificate specified by the presented digital certificate is presented. Only if it is included in the member list of the VPN server process identification information and the presented digital certificate is verified by the public key of the presented VPN server process identification information, the information terminal And permitting connection to a VPN server process whose ID is the hash value of the presented VPN server process identification information.

  According to a sixth aspect of the present invention, there is provided a VPN server hosting system comprising one or a plurality of host servers for executing a VPN server process for connecting a plurality of information terminals with a virtual dedicated line. Any of the above information terminals that have obtained a digital certificate from a certificate issuing device that generates a public key and private key pair and issues a digital certificate signed with the private key on the server computer A plurality of information terminals as members, and a VPN server process using a hash value of VPN server process specifying information consisting of a public key of the certificate issuing device and a member list for specifying the member as an ID, the predetermined host server The information terminal is configured to generate the VPN server process specific information and the issued When presenting a digital certificate and requesting a connection to the VPN server process, an information terminal that is the owner of the digital certificate specified by the presented digital certificate is provided by the presented VPN server process Only when it is included in the member list of specific information and the presented digital certificate is verified by the public key of the presented VPN server process specific information, it is presented to the information terminal. And a step of permitting connection to the VPN server process having the ID of the hash value of the VPN server process specifying information as an ID.

  According to the present invention, it is possible to flexibly and easily construct a VPN for members arbitrarily selected from a plurality of clients.

  According to the third aspect of the present invention, the hash value used as the ID of the VPN server process is managed by the distributed hash table, and the host server that generates the VPN server process is determined according to the distributed hash table. Therefore, the hosting system can autonomously distribute a large number of VPN server processes to the host servers. Thereby, it is possible to make the hosting system expandable with respect to an increase in the number of VPN server processes.

  According to the invention described in claim 4, since the two-stage message authentication using the first and second session keys is performed, message tampering (including one caused by the VPN server process) or illegal packet Can be effectively prevented. Further, the VPN server process can decrypt the header portion encrypted by the first session key (which can relay the packet), but the payload portion encrypted by the second session key can be decrypted. Therefore, it is possible to ensure the confidentiality of the communication contents for the operator operating the hosting system.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a diagram for explaining a situation in which a VPN is established between clients by using a VPN server hosting system 10 according to an embodiment of the present invention. In FIG. 1, the VPN server hosting system 10 is connected to the Internet 40. Further, clients (information terminals) 21-1 to 21-9 used by each user are connected to the Internet 40. In this embodiment, these clients generate a VPN server process in the VPN server hosting system 10 according to the procedure described later, construct a VPN, and perform mutual communication by VPN via this VPN server process. Examples of the client include a file server, a video server, a general personal computer, and the like, as well as all types of home appliances and information devices having a network function.

  The VPN server hosting system 10 is a server system composed of a plurality of (four here) host servers 11a to 11d, and is operated by, for example, an Internet service provider. These host servers 11a to 11d are computers that generate and execute a VPN server process that is responsible for connecting specified clients by VPN, and each of the host servers 11a to 11d is a VPN corresponding to an ID that it manages. Create and execute a server process.

The certificate issuing devices 31 a to 31 c are computers that generate a public key and private key pair and issue a client certificate (digital certificate) to the client 21. The client certificate contains the name and public key of the client that is the owner of the client certificate and the name and public key of the issuer (certificate issuing device), and the private key of the issuer. A signature by (a secret key paired with the public key) is attached. Also, here, the client 21-1~21-3 (a1, a2, a3) is issued a client certificate _{C A} from the certificate issuing unit 31a, the client 21-4~21-6 (b1, b2, b3) is issued a client certificate _{C B} from the certificate issuing unit 31b, the client 21-7~21-9 (u1, u2, u3) is issued a client certificate _{C CA} from the certificate issuing device 31c It shall be. The certificate issuing devices 31a and 31b are general personal computers owned and managed by the user, and the certificate issuing device 31c is an authentication computer operated by a third-party certification authority. However, the certificate issuing entity is an example and is not limited to this.

Next, referring to FIG. 2 to FIG. 4, a case where the four clients a1, b1, b2, and u1 in the configuration of FIG. 1 are members and a VPN that can be connected only to these members is constructed. The operation of the VPN server hosting system 10 will be described in detail as an example.
Hereinafter, description will be made in order along the flow of the flowchart shown in FIG.

(1) Generation of VPN Server Process First, each certificate issuing device 31a to 31c generates one pair of public key pk _X and private key sk _X (where X = A, B, CA) (step S11). Here, not be decrypted unless the secret key sk _X is encrypted data corresponding with the public key pk _X, unless the public key pk _X corresponding encrypted data using the private key sk _X Cannot decrypt. The secret key sk _X is managed so as not to be disclosed to any third party other than itself (each certificate issuing device 31a to 31c).

Each client a1, b1, b2, and u1 has its own client public key pk _Y and client secret key sk _Y used for authentication when connecting to the VPN server process (where Y = a1, b1, b2, u1). Create a pair. Each of the certificate issuing devices 31a to 31c has client certificates C _A (pk _a1 ) and C _B (pk) that prove that these client public keys belong to clients having authority to connect to the VPN server process. _b1 ), C _B (pk _b2 ), and C _CA (pk _u1 ) are issued by signing with the secret key sk _X , respectively (step S12). These client certificates are stored in the clients a1, b1, b2, and u1, respectively. The client secret key sk _Y is also managed so as not to be disclosed to any third party.

Next, one of the above members (here, client a1) knows the IP address and the public key of all certificate issuing devices that issued client certificates to each member and the list of members. It is requested to generate a VPN server process by sending it to one of the host servers (referred to as host server 11a) (step S13). Here, the arrangement order of the data to be sent (VPN server process specifying information) is such that the public key of the certificate issuing device and the client that has issued the client certificate from the certificate issuing device are arranged as a group. Specifically, in this example, the VPN server process identification information is
pk _A , {a1}, pk _B , {b1, b2}, pk _CA , {u1}
It becomes.

Here, the hash value H (pk _A , {a1}, pk _B , {b1, b2}, pk _CA , {u1}) of the VPN server process specific information is the VPN server process ID (VPN-ID). Is set. For example, when SHA-1 (Secure Hash Algorithm 1) is used as a hash function, a VPN server process having a hash value H () as a VPN-ID can be represented by one point in a 160-bit hash space. . That is, by associating the VPN-ID with the hash value by the hash function SHA-1, it is possible to manage ²¹⁶⁰ kinds of VPN server processes. Note that, from the characteristics of the hash function, a plurality of arbitrary VPN-IDs are statistically uniformly distributed in the hash space.

When the host server 11a receives the request at step S13, the host servers cooperate with each other, so that the VPN-ID has the hash value H (pk _A) among the host servers 11a to 11d constituting the VPN server hosting system 10. , {A1}, pk _B , {b1, b2}, pk _CA , {u1}) are searched for the host server responsible for the VPN server process (step S14). For this search, a distributed hash table (DHT) is used. Then, the VPN server process specifying information is transferred to the corresponding host server (referred to as host server 11c) as a result of the search.

Here, a VPN server process management method using DHT (which host server is responsible for a specific VPN server process) and a host server search method will be described with reference to FIG.
The figure shows a state in which a 4-bit hash space (considered with 4 bits for convenience to simplify the description) is managed by the four host servers 11a to 11d. That is, in this example, 2 ⁴ = 16 VPN server processes can be managed. The VPN-IDs of these VPN server processes are 0, 1, 2,. On the other hand, each host server has a unique identification number, the identification number of the host server 11a is 3, the identification number of the host server 11b is 7, the identification number of the host server 11c is 11, and the identification number of the host server 11d is 15 is assumed. Under such conditions, the host server 11a manages VPN server processes with VPN-ID = 0-3, and the host server 11b manages VPN server processes with VPN-ID = 4-7, As described above, the correspondence between each host server and the VPN server process assigned to it is determined. Each host server holds a DHT, which is a table that defines the range of VPN-IDs (ie, hash values) assigned to the host server, and uses it for searching (below).

  The search for the host server is performed according to the following method. In the 4-bit hash space shown in FIG. 3, the VPN-ID of the VPN server process requested in step S13 is “9”. The host server 11a (host server that received the request) refers to the DHT held by itself, and the hash value (VPN-ID) “9” to be searched is a hash value within the range managed by the host server 11a. It is determined whether or not. Since the hash value “9” is not under the management of the host server 11a, the host server 11a transfers the data (public key pk and VPN setting information) to the adjacent host server 11b. Similarly, the host server 11b performs a determination process with reference to its own DHT, and since the hash value “9” is not under management, the data is transferred to the adjacent host server 11c. Since the host server 11c includes the hash value “9” to be searched for in its own DHT, the host server 11c determines that it is the person responsible for the requested VPN server process. By performing routing in such a procedure, the target host server is searched.

Returning to the flowchart of FIG.
Next, the host server 11c corresponding to the search result in step S14 uses the hash value H (pk _A , {a1}, pk _B , {b1, b2}, pk _CA , {u1}) as a VPN-ID VPN. A server process is generated (step S15).

(2) VPN construction (connection to VPN server process)
Next, the client (here, referred to as client b1) connects to the generated VPN server process by VPN according to the following procedure.
First, the client b1 is, VPN-ID of the VPN server process to the desired connection, the hash value _{H (pk A, {a1}} , pk B, {b1, b2}, pk CA, {u1}) to the host server The necessary connection information is inquired by transmitting to one device (step S21). The transmission destination is the host server 11a that knows the IP address.

  When the host server 11a receives the VPN-ID, a search for the host server is executed by routing using DHT as in step S14 described above, and the VPN-ID is stored in the host server 11c (the VPN server process of the VPN-ID is Generated and transferred to a host server that is running. Upon receiving the VPN-ID, the host server 11c returns connection information such as its own IP address and the port number of the VPN server process related to the inquiry to the client b1 (step S22). At this time, the response is returned via the host server that received the inquiry first (host server 11c → 11a → client b1). By receiving the connection information, the client b1 knows that the VPN server process to be connected is operating on the host server 11c.

Next, the client b1 requests connection to the target VPN server process using the acquired connection information. Specifically, VPN server process specific information (pk _A , {a1}, pk _B , {b1, b2}, pk _CA , {u1}) and is issued and stored in step S12 directly to the host server 11c. The received client certificate C _B (pk _b1 ) is transmitted (step S23). The host server 11c calculates the hash value of the sent VPN server process identification information and verifies whether or not it matches the VPN-ID of the running VPN server process (step S24). When the hash value and the VPN-ID match, the owner (here, client b1) described in the client certificate C _B (pk _b1 ) is further included in the member list of the VPN server process specifying information. It is verified whether or not (step S25). If it is included in the member list, the client certificate C _B (pk _b1 ) is further verified using the public key (here, pk _B ) of the certificate issuing device corresponding to the owner (step S26). . If the client certificate C _B (pk _b1 ) can be correctly verified with the public key pk _B , then the host server 11c sends a one-time challenge message to the client b1, and the client private key sk _b1 for that message. Add the signature by and send it back. Then, this signature is verified by the client public key pk _b1 described in the client certificate C _B (pk _b1 ), and it is confirmed that the client b1 surely possesses the client private key sk _b1 . As described above, since it is proved that the client b1 has a proper connection authority, the connection to the target VPN server process is permitted (step S27). On the other hand, if the verification in steps S24 to S26 fails, the connection is rejected (step S17).

Thus, the VPN is connected between the client b1 and the VPN server process. The other client (for example, client a1) included in the member of the VPN server process specifying information is connected to the VPN server process by performing the same procedure using the client certificate C _A (pk _a1 ). . In this way, a VPN is established between the members via the VPN server process.

(3) Preparation for VPN Communication A procedure for performing VPN communication between the client a1 and the client b1 among the members using the VPN constructed as described above will be described. Note that VPN communication can be performed by the same procedure for the client b2 and the client u1, which are other members.
The VPN server process creates shared session keys K ^s _mac and K ^s _nc for message authentication and packet encryption, and transmits these shared session keys to the clients a1 and b1 (step S31). Transmission is performed by encrypted communication using the client public keys pk _a1 and pk _b1 of the transmission partner. This shared session key is shared by the VPN server process, the client a1, and the client b1, and is used in VPN communication described below.

Similarly, the client a1 (or client b1) creates client session keys K ^u _mac and K ^u _enc for message authentication and packet encryption, and uses these as client public keys of the client b1 (or client a1). pk _b1 (or _{pk a1)} using the shared session key on encrypted with sending to the client b1 (or client a1) (step S32). The client b1 (client a1) decrypts the received client session key with the shared session key and its own client secret key sk _b1 (or sk _a1 ), and acquires a plaintext client session key. The client session key is used in the VPN communication together with the shared session key, but is shared only between the client a1 and the client b1 by exchanging in the above procedure. .

  When the shared session key and the client session key are shared by the above steps, preparation for VPN communication is completed. The client a1 and the client b1 use the shared session key and the client session key to perform communication by VPN via the VPN server process (step S33). Hereinafter, a specific VPN communication method will be described with reference to FIG.

(4) Execution of communication by VPN FIG. 4 is a diagram showing the structure of a packet transmitted and received when communication is performed from the client a1 to the client b1 by VPN. Message authentication is performed using a total of four session keys described above. It shows how a packet is encrypted / decrypted. The client a1, which is a sender, encrypts the header part of the packet with K ^s _enc and the payload part with K ^u _enc , and further creates the message authentication code MAC _u and the message generated from the message (header + payload) and K ^u _mac And MAC _s created from K ^s _mac are added to the end of the packet. The message authentication code (MAC) is an output value of fixed length bits obtained by inputting a message and a key to a predetermined MAC function. Then, the key used for the input is shared between the sender and the receiver, and if the MAC calculated from the received message and the shared key matches the MAC added to the received message, the receiver Confirm that the message has not been tampered with (message authentication).

The VPN server process verifies the message authentication code MAC _s using the shared session key K ^s _mac with _respect to the packet with the MAC added and encrypted, and if the verification is successful, the MAC _s is determined from the packet. At the same time, the header is decrypted using the shared session key K ^s _nc and the packet is delivered to the destination client b 1 according to the header. At this time, since the VPN server process does not own the client session key, the payload cannot be decrypted.

The client b1 analyzes the header with the shared session key K ^s _nc and selects a packet addressed to itself, and verifies the message authentication code MAC _u added to the end of the packet with the client session key K ^u _mac . Once verified, the payload is decrypted with the client session key K ^u _enc to obtain plain text transmission data. In this way, VPN communication is performed between the client a1 and the client b1 while keeping the communication contents secret from the VPN server process.

As described above, the embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to the above, and various design changes and the like can be made without departing from the scope of the present invention. It is possible to
For example, DHT itself is an existing technology used for P2P (Peer to Peer) file exchange, and any of various methods such as Chord, CAN, and Tapestry can be applied.

  It is also possible to cause a computer of the server device to execute a computer program for realizing the function of the VPN server hosting system according to the above embodiment.

It is a figure explaining the condition where VPN is constructed between clients using the VPN server hosting system concerning one Embodiment of this invention. It is the flowchart which showed operation | movement of the VPN server hosting system of FIG. It is the figure explaining the mechanism which manages a VPN server process by DHT. It is the figure which showed the structure of the packet transmitted / received in VPN communication.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... VPN server hosting system 11a-11d ... Host server 21 ... Client (information terminal) 31 ... Certificate issuing apparatus 40 ... Internet

Claims (6)

A VPN server hosting system comprising one or a plurality of host servers for executing a VPN server process for connecting a plurality of information terminals with a virtual dedicated line,
A plurality of information arbitrarily specified from among the information terminals that generate a digital certificate from a certificate issuing device that generates a public key and a private key pair and issues a digital certificate signed with the private key A VPN having a terminal as a member and generating a VPN server process in the predetermined host server with a hash value of VPN server process specifying information consisting of a public key of the certificate issuing device and a member list for specifying the member as an ID Server generation means;
The digital certificate specified by the presented digital certificate when the information terminal requests the connection to the VPN server process by presenting the VPN server process identification information and the issued digital certificate An information terminal which is the owner of the VPN server process is included in the member list of the presented VPN server process identification information, and the presented digital certificate is verified by the public key of the presented VPN server process identification information VPN server connection means for permitting connection to a VPN server process with the hash value of the presented VPN server process identification information as an ID only to the information terminal,
A VPN server hosting system comprising: At least one information terminal included in the member does not have a digital certificate issued to another information terminal, and is different from the certificate issuing apparatus that issued the digital certificate If you have a digital certificate issued by
2. The VPN server hosting system according to claim 1, wherein the VPN server process specifying information includes each public key of all the certificate issuing devices and a member list that specifies the members. Each of the host servers holds a distributed hash table that defines the range of the hash values that it manages,
The VPN server generating means selects a host server corresponding to the hash value of the VPN server process specifying information according to the distributed hash table, and generates a VPN server process in the selected host server. The VPN server hosting system according to claim 1 or 2. Session key generation means for generating a first session key shared by the VPN server process and the plurality of information terminals in communication between information terminals permitted to connect to the VPN server process by the VPN server connection means; ,
A message authentication code is added using the first session key and a second session key shared only between the information terminals, and a header is encrypted using the first session key, and the A packet analysis means for performing message authentication and decryption of the header using the first session key for a packet whose payload is encrypted using a second session key;
The VPN server hosting system according to any one of claims 1 to 3, further comprising: A VPN construction method for constructing a VPN by executing a VPN server process for connecting a plurality of information terminals with a virtual dedicated line to any one of the host servers in a server system composed of one or a plurality of host servers. ,
A plurality of information arbitrarily specified from among the information terminals that generate a digital certificate from a certificate issuing device that generates a public key and a private key pair and issues a digital certificate signed with the private key Creating a VPN server process in a predetermined host server with a terminal as a member and using as a ID a hash value of VPN server process specifying information comprising a public key of the certificate issuing device and a member list for specifying the member When,
The digital certificate specified by the presented digital certificate when the information terminal requests the connection to the VPN server process by presenting the VPN server process identification information and the issued digital certificate An information terminal which is the owner of the VPN server process is included in the member list of the presented VPN server process identification information, and the presented digital certificate is verified by the public key of the presented VPN server process identification information Only when the information terminal is allowed to connect to the VPN server process whose ID is the hash value of the presented VPN server process identification information;
A VPN construction method comprising: In a VPN server hosting system comprising one or a plurality of host servers for executing a VPN server process for connecting a plurality of information terminals with a virtual dedicated line, the computers of the host servers are respectively
A plurality of information arbitrarily specified from among the information terminals that generate a digital certificate from a certificate issuing device that generates a public key and a private key pair and issues a digital certificate signed with the private key Creating a VPN server process in a predetermined host server with a terminal as a member and using as a ID a hash value of VPN server process specifying information comprising a public key of the certificate issuing device and a member list for specifying the member When,
The digital certificate specified by the presented digital certificate when the information terminal requests the connection to the VPN server process by presenting the VPN server process identification information and the issued digital certificate An information terminal which is the owner of the VPN server process is included in the member list of the presented VPN server process identification information, and the presented digital certificate is verified by the public key of the presented VPN server process identification information Only when the information terminal is allowed to connect to the VPN server process whose ID is the hash value of the presented VPN server process identification information;
A computer program for running.

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