JP2006019824A - Secure communication system, management apparatus, and communication terminal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a secure communication system smoothly coping with change of a security policy in secure communication and relieving the load imposed on a communication terminal. <P>SOLUTION: The secure communication system includes a plurality of communication terminals 1 belonging to groups for carrying out the secure communication, a database 10 for storing security policies to be set to the communication terminals 1, and a management server 2. The database 10 stores the security policies and multicast addresses by each group of the communication terminals 1, when the security policy in the database 10 is changed, the management server 2 uses the multicast address of the group to transmit the change information, and each communication terminal 1 updates the security policy stored in its own terminal 1 on the basis of the change information of the security policy received in the multicast form. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a secure communication system, a management device, and a communication terminal.

  Conventionally, as a protocol for performing secure communication on an IP (Internet Protocol) network, a method called IPsec defined by RFC2401 (Security Architecture for the Internet Protocol) of IETF (Internet Engineering Task Force) is known. Yes. IETF is known as a substantial standardization organization for technologies used on the Internet such as TCP (Transmission Control Protocol) / IP. In addition, as an automatic secret key generation and management protocol required when using IPsec, a method called IKE is defined in RFC 2409 (The Internet Key Exchange) of IETF.

  The settings required when using the above-described IPsec and IKE are generally complicated. For example, when secure communication is performed between communication terminals using IPsec, it is necessary to negotiate setting items with a communication partner in advance to communicate with IPsec. For this reason, it is difficult for general users to use IPsec. Further, even if a user has specialized knowledge, it is difficult to immediately communicate with IPsec when performing secure communication because prior negotiation with a communication partner is necessary.

As a conventional technique for dealing with the above-described problems, a communication management server that stores a security policy such as IPsec and IKE setting information to be set by a communication terminal, and a communication terminal that performs secure communication can perform communication at any time or periodically. It is known to access a management server, acquire a security policy related to a plurality of communication partners to be set in the secure communication, perform settings related to IPsec and IKE using the acquired security policy, and perform secure communication. (For example, refer to Patent Document 1).
JP 2004-48458 A

  However, in the conventional technology described above, the communication terminal cannot smoothly respond to the change of the security policy unless it acquires the latest security policy from the communication management server whenever it performs secure communication. For this reason, there exists a problem that the load concerning a communication terminal is large and is a burden. In addition, if the access to the communication management server is made only periodically to reduce the load on the communication terminal, if the security policy has been changed, secure communication may be performed without obtaining the latest security policy. There arises a situation where secure communication fails.

  Also, when starting secure communication, in order to know whether the communication partner's terminal is ready to accept secure communication, actually send a connection request in secure communication to the communication partner in a packet, It is necessary to determine whether there is a response. For this reason, every time secure communication is started in the communication terminal, a load for confirming the completion of preparation of the communication partner is generated and becomes a burden.

  The present invention has been made in consideration of such circumstances, and its object is to provide a secure communication system that can smoothly cope with a change in security policy in secure communication and can reduce the burden on a communication terminal. Is to provide.

  Another object of the present invention is to provide a management apparatus and a communication terminal applicable to the secure communication system of the present invention.

  In order to solve the above problems, a secure communication system according to the present invention includes a plurality of communication terminals belonging to a group performing secure communication, and a management apparatus having a database that stores a security policy to be set in the communication terminals. The database stores the security policy and multicast address for each group of communication terminals, and the management device changes the security policy when the security policy in the database is changed. Change information transmitting means for transmitting information using the multicast address of the group, and the communication terminal stores a security policy in the same group as the receiving means for receiving information from the network based on the multicast address Group A distribution storage means, based on the change information security policies received in multicast format, is characterized by having a updating means for updating the security policy in the group information storage means.

  In the secure communication system according to the present invention, the communication terminal transmits a user advertisement message indicating that the terminal is in a state of accepting secure communication using the multicast address, Security policy database storage means for storing a security policy for each other communication terminal, and based on the reception status of user advertisement messages from other communication terminals in the same group, the message transmission source terminal in the security policy database storage means Security policy setting means for writing or deleting a security policy for use.

  The management device according to the present invention is a management device having a database that stores a security policy to be set in a plurality of communication terminals belonging to a group that performs secure communication, and the database is provided for each group of the communication terminals. Storing the security policy and the multicast address, and the management device has a change information transmitting means for transmitting the change information using the multicast address of the group when the security policy in the database is changed. It is a feature.

  A communication terminal according to the present invention is a communication terminal belonging to a group that performs secure communication, a receiving unit that receives information from a network based on a multicast address of the group, and a group that stores a security policy in the group The information storage means and update means for updating the security policy in the group information storage means based on the change information of the security policy received in the multicast format.

  In the communication terminal according to the present invention, a message transmission means for transmitting a user advertisement message indicating that the terminal is in a state of accepting secure communication using the multicast address, and for each other communication terminal in the same group Based on the security policy database storage means for storing the security policy and the reception status of user advertisement messages from other communication terminals in the same group, the security policy for the sender terminal of the message is written in the security policy database storage means Or security policy setting means for deleting.

  According to the present invention, when the security policy of a certain group is changed, the management terminal distributes the security policy change information to the communication terminals in the group in a multicast format, so that the communication terminal can change the security policy. As a result, the burden of inquiring about the change of the security policy can be reduced.

  In addition, since the communication terminal notifies other communication terminals in the same group in a multicast format that it is in a state of accepting secure communication, when the secure communication is started, the communication partner terminal is prepared to accept secure communication. Since it is possible to know in advance whether the communication is ready, the burden of confirming that the communication partner is ready is reduced.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a configuration of a secure communication system according to an embodiment of the present invention. In FIG. 1, a communication terminal 1 has a function of performing secure communication using the IPsec and IKE methods. The management server 2 manages a group configuration of secure communication parties, a security policy to be set in the communication terminal 1 during secure communication, and the like. The CA (authentication) server 3 issues and manages public key certificates. The IP network 4 is a packet communication network using an IP version 6 (IPv6) or IP version 4 (IPv4) protocol. The IP network 4 supports multicast type packet communication using a multicast address. The communication terminal 1, the management server 2, and the CA server 3 are each connected to the IP network 4 and can perform packet communication via the IP network 4.

  The database 10 stores the group configuration of secure communicators and the security policy to be set by the communication terminal 1 during secure communication, and is accessed from the management server 2. FIG. 2 is a diagram illustrating a configuration example of the database 10. In FIG. 2, the database 10 stores group information for each group of secure communicators. The group information includes a group identifier (group ID) for identifying a group of secure communication parties, a user identifier (user ID) for identifying a user belonging to the group, a multicast address assigned to the group, and a security policy used in the group. And information including a group key shared between users in the group. The security policy includes IPsec and IKE setting information that should be set by the communication terminal. For example, it includes information such as a protocol type and a hash function type used for encryption.

  The group information stored in the database 10 can be changed only by the manager of the management server 2 or the manager of the group. When the security policy of a certain group is changed, the management server 2 uses the multicast address of the group as the destination address, and multicasts the policy change message via the IP network 4. The policy change message includes information on a changed part of the security policy. Further, it includes a public key certificate of the management server 2 issued by the CA server 3 and an electronic signature created using the private key of the management server 2. Thereby, the communication terminal 1 that has received the policy change message can determine whether or not the received policy change message has been transmitted from the regular management server 2. When transmitting the policy change message, the management server 2 encrypts it using the group key of the group.

  FIG. 3 is a block diagram showing a configuration of communication terminal 1 shown in FIG. In FIG. 3, the management server communication unit 11 communicates with the management server 2 via the IP network 4 using a security protocol such as SSL (Secure Sockets Layer) or TLS (Transport Layer Security). Get a group's multicast address, security policy, and group key. The acquired information is stored in a group database (group DB) 12. The group DB 12 stores information common to all users in the group to which the group belongs.

  The multicast message transmission unit 13 uses the multicast address stored in the group DB 12 as the destination address, and multicasts the user advertisement message via the IP network 4. This user advertisement message is distributed when the terminal is ready to accept secure communication.

FIG. 4 is a diagram illustrating a configuration example of a user advertisement message. In FIG. 4, the user advertisement message is created based on UDP (User Datagram Protocol). The UA header part has a sequence number. The sequence number is incremented by 1 for each delivery of the user advertisement message. The UA data part has a group ID, its own user ID, its own IP address, its own public key certificate issued by the CA server 3, and an electronic signature. For the electronic signature, the data in the UA header part and the group ID, user ID, IP address, and public key certificate data in the UA data part are converted by a hash function, and this hash data is encrypted with its own private key. Create. And about the UA data part, the data encrypted using the group key of the group to which it belongs is distributed.
As the hash function and encryption algorithm for creating the electronic signature and the group key and encryption algorithm for encrypting the user advertisement message, those stored in the group DB 12 are used.

  The multicast message receiver 14 receives a packet from the IP network 4 based on the multicast address stored in the group DB 12. For example, a policy change message is received, information on the changed part of the security policy in the policy change message is extracted, and the security policy in the group DB 12 is updated based on this information. Also, the user advertisement message is received, user-specific data (user ID, IP address, sequence number, and public key certificate) in the user advertisement message is extracted, and this data is stored in the group user database (group user DB) 15. Store. The group user DB 15 stores information for each user in the group to which the user belongs.

  The IKE / IPsec setting unit 16 writes setting information related to IPsec and IKE in the setting information storage unit 17 based on the security policy in the group DB 12. The setting information storage unit 17 stores setting information for each user in the belonging group. When the IKE / IPsec setting unit 16 receives a user advertisement message from a certain user for the first time, the IKE / IPsec setting unit 16 writes the setting information for the user in the setting information storage unit 17. Then, while the reception of the user advertisement message is continued, the written setting information is maintained. However, when reception of a user advertisement message from a certain user is interrupted for a certain period, the setting information for the user is deleted from the setting information storage unit 17. Note that the setting information related to IPsec and IKE stored in the setting information storage unit 17 is used by a functional unit (not shown) that executes secure communication.

  The user certificate storage unit 18 stores its own public key certificate, public key, and private key issued by the CA server 3.

Next, operations related to the above-described secure communication system of FIG. 1 will be described.
FIG. 5 is a sequence diagram showing a flow of processing related to the secure communication system shown in FIG.
First, the user has his / her public key certificate issued from the CA server 3. Here, the user generates a set of a public key and a secret key, and transmits the public key to the CA server 3. The CA server 3 creates and returns a public key certificate for the public key received from the user. The user stores the public key certificate received from the CA server 3 and the set of the public key and the private key in the communication terminal 1 (user certificate storage unit 18).
Next, the user applies for belonging to one of the groups of secure correspondents. When this application is permitted, the group manager updates the database 10 to include the user ID of the user in the own group information.

  In FIG. 5, for example, the user “abc” belonging to the group ID “soumu” in FIG. 2 accesses the management server 2 using the communication terminal 1 and requests a communication connection using a secure protocol such as SSL or TLS (step S1). ). Next, the communication terminal 1 and the management server 2 each present a public key certificate and perform mutual authentication (step S2). If this mutual authentication is successful, the management server 2 reads out the group information to which the user belongs from the database 10 and transmits it to the communication terminal 1 (step S3). This group information includes the multicast address, security policy, and group key of the group to which the user belongs. If mutual authentication fails, communication between the communication terminal 1 and the management server 2 is terminated at that time.

  Next, when receiving the group information from the management server 2, the communication terminal 1 stores the received information in the group DB 12. Then, the user advertisement message is periodically transmitted using the multicast address in the group information as the destination address (step S4). Thereby, the other users “cba” and “def” belonging to the group ID “soumu” receive the user advertisement message from the user “abc” based on the multicast address.

  The communication terminal 1 receives a user advertisement message from another user “cba” or “def” based on the multicast address (step S5). FIG. 6 is a process flow diagram when receiving a user advertisement message in the communication terminal 1. In FIG. 6, when the communication terminal 1 receives a user advertisement message from a certain user (step S <b> 101), the communication terminal 1 verifies the sequence number in the user advertisement message based on the sequence number received in the past in the group user DB 15. (Step S102). If the sequence number received this time is M or more larger than the sequence number received in the past (M is a natural number) or the same as the sequence number received in the past, the received user advertisement message is discarded. (Step S103).

  Next, when the verification of the sequence number is successful, the communication terminal 1 decrypts the user advertisement message using the group key in the group DB 12 (step S104). Next, the format of the decrypted user advertisement message is verified, and it is determined whether or not the contents of the message can be understood (step S105). If this verification fails, the user advertisement message is discarded (step S103).

  Next, when the verification in step S104 is successful, the communication terminal 1 verifies the electronic signature in the user advertisement message (step S106). In this verification, first, based on the public key certificate of the user in the group user DB 15, the public key certificate in the user advertisement message is verified. If the public key certificate is valid as a result of this verification, the electronic signature in the user advertisement message is verified using the public key included in the electronic certificate in the user advertisement message. If the verification of the electronic signature fails (NO in step S107), the user advertisement message is discarded (step S103).

  On the other hand, if the verification of the electronic signature is successful (YES in step S107), data (user ID, IP address, sequence number, and public key certificate) in the user advertisement message is extracted, and each data is associated with the user ID. Is stored in the group user DB 15 (step S108). Next, the communication terminal 1 writes the setting information related to IPsec and IKE for the user in the setting information storage unit 17 based on the security policy in the group DB 12 (step S109). As a result, a security policy database for the user is generated in the setting information storage unit 17. Since the user advertisement message is transmitted when the communication terminal is ready to accept secure communication, the presence of the security policy database indicates that the user's communication terminal can accept secure communication.

  Next, the communication terminal 1 monitors whether or not a user advertisement message has been received from the user for which the security policy database has been generated. If the state without receiving the user advertisement message continues for a predetermined period, it is determined that secure communication cannot be accepted in the communication terminal of the user, and the security policy database of the user is deleted.

  As a result, when the communication terminal 1 starts communication, it first searches the setting information storage unit 17 to determine whether there is a security policy database for the communication partner, that is, IPsec for the communication terminal of the communication partner. And whether or not the setting information related to IKE has been set. Based on this confirmation result, it is possible to determine whether or not secure communication by the IPsec and IKE method is possible with the communication terminal of the communication partner. That is, when the security policy database exists, that is, when the setting information related to IPsec and IKE has been set, it is determined that secure communication by the IPsec and IKE method can be performed with the communication terminal of the communication partner. On the other hand, when the security policy database does not exist, that is, when setting information related to IPsec and IKE is not set, it is determined that secure communication using the IPsec and IKE schemes cannot be performed with the communication terminal of the communication partner.

  When executing secure communication, if a secure communication path (SA) has already been established, a packet is transmitted using the SA. On the other hand, when the SA is not established, the SA is established with the destination communication terminal of the packet by IKE, and then the packet is transmitted using the SA.

  As described above, according to the present embodiment, when a security policy of a certain group is changed, information on the changed part of the security policy is distributed from the management server to the communication terminals in the group in a multicast format. Accordingly, the communication terminal can smoothly cope with the change of the security policy, and the burden of inquiring about the change of the security policy is reduced.

  In addition, since the communication terminal notifies other communication terminals in the same group in a multicast format that it is in a state of accepting secure communication, when the secure communication is started, the communication partner terminal is prepared to accept secure communication. It is possible to know in advance whether or not Thus, every time secure communication is started, trial packet transmission for confirming completion of preparation of the communication partner and determination of presence / absence of a response become unnecessary, and the load on the communication terminal is reduced.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes design changes and the like within a scope not departing from the gist of the present invention.

It is a block diagram which shows the structure of the secure communication system which concerns on one Embodiment of this invention. 2 is a diagram illustrating a configuration example of a database 10. FIG. It is a block diagram which shows the structure of the communication terminal 1 shown in FIG. It is a figure which shows the structural example of a user advertisement message. It is a sequence diagram which shows the flow of the process which concerns on the secure communication system shown in FIG. It is a processing flow figure at the time of the user advertisement message reception in the communication terminal 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Communication terminal, 2 ... Management server, 3 ... CA server, 4 ... IP network, 10 ... Database, 11 ... Management server communication part, 12 ... Group database (group DB), 13 ... Multicast message transmission part, 14 ... Multicast Message receiving unit, 15 ... group user database (group user DB), 16 ... IKE / IPsec setting unit, 17 ... setting information storage unit, 18 ... user certificate storage unit.

Claims (5)

A secure communication system having a plurality of communication terminals belonging to a group that performs secure communication, and a management device having a database that stores a security policy to be set in the communication terminal,
The database is
Storing the security policy and multicast address for each group of communication terminals;
The management device
When the security policy in the database is changed, the information management device includes change information transmission means for transmitting the change information using the multicast address of the group,
The communication terminal is
Receiving means for receiving information from the network based on the multicast address;
Group information storage means for storing security policies within the same group;
An update means for updating a security policy in the group information storage means based on the change information of the security policy received in a multicast format. The communication terminal is
Message transmitting means for transmitting a user advertisement message indicating that the terminal is in a state of accepting secure communication using the multicast address;
Security policy database storage means for storing a security policy for each other communication terminal in the same group;
Security policy setting means for writing or deleting a security policy for the sender terminal of the message in the security policy database storage means based on the reception status of user advertisement messages from other communication terminals in the same group;
The secure communication system according to claim 1, comprising: A management apparatus having a database for storing security policies to be set in a plurality of communication terminals belonging to a group performing secure communication,
The database is
Storing the security policy and multicast address for each group of communication terminals;
The management device
A management apparatus comprising: a change information transmitting unit that transmits the change information using a multicast address of the group when a security policy in the database is changed. A communication terminal belonging to a group performing secure communication,
Receiving means for receiving information from the network based on the multicast address of the group;
Group information storage means for storing a security policy in the group;
An update means for updating a security policy in the group information storage means based on the security policy change information received in a multicast format. Message transmitting means for transmitting a user advertisement message indicating that the terminal is in a state of accepting secure communication using the multicast address;
Security policy database storage means for storing a security policy for each other communication terminal in the same group;
Security policy setting means for writing or deleting a security policy for the sender terminal of the message in the security policy database storage means based on the reception status of user advertisement messages from other communication terminals in the same group;
The communication terminal according to claim 4, further comprising:

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