JP2007267301A - Encrypted communication system, and encryption key updating method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To facilitate the generation of an encryption key and to perform relief if encryption keys are not coincident between transmitting and receiving sides. <P>SOLUTION: The present invention relates to an encrypted communication system and an encryption key updating method including a supervisory and control server 4 for distributing a VLAN enabled encryption key to IPsec gateways 2-1, 2-2 to which a single or multiple terminals 1-1 to 1-9 are connected, wherein the supervisory and control server 4 utilizes a priority of a VLAN enabled VLAN name, a part of the VLAN name or a VLAN tag to generate and manages the VLAN enabled encryption key, distributes this encryption key to the IPsec gateways 2-1, 2-2 and updates the VLAN enabled VLAN name at predetermined time intervals. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an encryption communication system and an encryption key update method for performing communication by encrypting with a different encryption key for each group.

  There are various types of networks that connect terminals and perform data transmission between them. For example, in a corporate area network (LAN), a LAN switch is provided independently of a physical connection form. A VLAN (Virtual Local Area Network) that forms a virtual group corresponding to the MAC address, IP address, and the like of a terminal connected via the network has been put into practical use. In this VLAN, since it is not premised on performing encrypted communication, there is a possibility that the contents of communication may be intercepted or altered by a third party.

  Therefore, for example, IPsec (Internet Protocol Security for Internet Protocol) is applied as a means for performing encrypted communication in IP packet transmission. In this case, the encryption type and the encryption key agreement are referred to as SA (Security Association). For example, IPsec policy and encryption method negotiation, key exchange, mutual authentication, and the like are performed by IKE (Internet Key Exchange).

  For example, as shown in FIG. 13, terminals 100-1, 100-2, 100-5, 100-6, and 100-7 among terminals 100-1 to 100-9 are connected to IPsec gateways 101-1, 101-. 2 shows a case where a VLAN is configured with a VLAN ID in a system connected via a network 103, and the terminal 100-1 and the terminal 100-5 are the same via the IPsec gateways 101-1 and 101-2. The VLAN ID: 1000 constitutes one group, and similarly, the terminal 1000-2 and the terminal 100-6 constitute one group by the same VLAN ID: 2000 via the IPsec gateways 101-1 and 101-2. ing. The VLAN ID of the terminal 100-8 is the same as the group of the terminals 100-1 and 100-5, and the VLAN ID of the terminal 100-3 is the same as the group of the terminals 100-2 and 100-6. . In the case of such a system, even if the VLAN is configured with only the VLAN ID, the confidentiality between the VLANs is lowered.

In addition, in the VLAN without performing address conversion by any processing function provided in the router between any of the plurality of closed networks connected via the wide area network by IPsec and any of the plurality of closed networks in the VLAN. There is known a system in which a closed network is identified by a VLAN tag and transmits an IP packet (see, for example, Patent Document 1). In addition, a key management server that generates a secret key is provided, the same secret key is transmitted to terminals that perform mutual communication, mutual authentication is performed using this secret key, and encrypted communication is performed using the secret key after authentication. Is also known (see, for example, Patent Document 2).
Japanese Patent No. 3491828 JP 2002-290397 A

  In the system as shown in FIG. 13, when terminals belonging to other groups having the same VLAN ID are connected to the network 103, if the encrypted communication is not performed, the terminal having the same VLAN ID communicates. Can be easily intercepted. Therefore, it is conceivable to perform encrypted communication between the IPsec gateways 101-1 and 101-2. In that case, if the same encryption key is used in all groups, the confidentiality of communication with respect to those other than the VALN group can be maintained, but there remains a problem that the confidentiality of communication between the groups is not sufficient. Thus, although it is conceivable to assign an encryption key to the group, communication security is not sufficiently maintained when the same encryption key is continuously used. For this purpose, means for updating the encryption key are also known, but if the encryption key is updated during communication, different encryption keys may be used, and communication must be interrupted or stopped. There is a problem that must happen.

  The present invention solves the above-mentioned problems, makes it possible to easily generate different encryption keys for each VLAN, and updates the encryption keys and problems due to differences in the encryption keys between them. It aims at solving.

  The encryption communication system of the present invention is an encryption communication system including a monitor control server that distributes a VLAN compatible encryption key to an IPsec gateway to which a single or a plurality of terminals are connected. A VLAN name corresponding to the VLAN or a part of the VLAN name is managed as an encryption key corresponding to the VLAN, and the encryption key is distributed to the IPsec gateway.

  The monitoring control server includes means for extracting, managing, and distributing the encryption key by extracting the VLAN name corresponding to the VLAN ID according to the type by the priority bit of the VLAN tag.

  The monitoring control server includes means for changing the VLAN name corresponding to the VLAN ID at a predetermined time interval and generating the encryption key.

  The monitoring control server may include means for distributing the encryption key via an out-band port of the IPsec gateway.

  The monitoring control server includes means for configuring an in-band VLAN with the IPsec gateway, and encrypting and distributing the encryption key using the in-band VLAN with the in-band VLAN name as a common key. it can.

  In an encryption communication system including a monitoring control server that distributes a VLAN-compatible encryption key to an IPsec gateway to which a single or a plurality of terminals are connected, the monitoring control server distributes the VLAN to the IPsec gateway. The IPsec gateway includes a new key memory for holding the currently distributed encryption key from the monitoring control server as a new key, and the previously distributed encryption key as an old key. An old key memory to be held; and means for switching to encrypted communication using the old key held in the old key memory due to unsuccessful encryption communication using the new key.

  In addition, the monitoring control server distributes the encryption key distributed to the IPsec gateway on the receiving side by a key distribution data table that holds the encryption key distributed to the IPsec gateway and a key mismatch notification from the IPsec gateway on the transmitting side. Means for reading a key from the key distribution data table and distributing the key to the transmitting side IPsec gateway, wherein the transmitting side IPsec gateway has a spare memory for holding the distributed encryption key; Means for performing encrypted communication using the stored encryption key.

  The monitoring control server includes means for adding time information indicating a time at which the encryption key is valid to the encryption key for the IPsec gateway for distribution, and the IPsec gateway has a current time according to the time information. Means can be provided for performing encrypted communication using the encryption key when the time has passed.

  The encryption key update method of the present invention is the encryption key update method for performing encrypted communication by distributing a VLAN-compatible encryption key from a monitoring control server to an IPsec gateway to which a single or a plurality of terminals are connected. The monitoring control server distributes the VLAN name corresponding to the VLAN or a part of the VLAN name to the IPsec gateway as the VLAN-compatible encryption key, changes the VLAN name at a predetermined time interval, and sets the VLAN name. It includes a process of changing the encryption key corresponding to the VLAN by changing and distributing the encryption key to the IPsec gateway.

  In addition, the monitoring control server includes a process in which the VLAN name corresponding to the VLAN ID is extracted according to the type corresponding to the priority bit of the VLAN tag, and the encryption key is generated, managed, and distributed.

  Also, in an encryption key update method for performing encryption communication by distributing a VLAN-compatible encryption key from a monitoring control server to an IPsec gateway to which a single or a plurality of terminals are connected, the IPsec gateway is connected to the monitoring control server from the monitoring control server. A new key memory that holds the encryption key distributed this time as a new key and an old key memory that holds the previously distributed encryption key as an old key, and is held in the new key memory in the IPsec gateway on the receiving side. When it cannot be decrypted with the encryption key of the new key, it is decrypted with the encryption key of the old key held in the old key memory, and when it cannot be decrypted with the encryption key of the new key and the old key, A key mismatch notification is transmitted to the gateway, and the IPsec gateway on the transmission side includes a process of encrypting and retransmitting with the encryption key of the old key held in the old key memory Than is.

  The monitoring control server includes a key distribution data table that holds the encryption key distributed to the IPsec gateway in correspondence with the IPsec gateway, and receives a key mismatch notification from the transmission side IPsec gateway when the encryption key is updated. The encryption key distributed to the IPsec gateway is read from the key distribution data table and distributed to the IPsec gateway on the transmission side, and the transmission side IPsec gateway includes a spare memory for holding the distributed encryption key, This includes a process of performing encrypted communication using the encryption key held in the spare memory.

  The monitoring control server distributes the encryption key updated at a predetermined time interval with respect to the IPsec gateway by adding time information for validating the encryption key, and the IPsec gateway has a current time according to the time information. A process of performing cryptographic communication using the encryption key when the time has passed can be included.

  By generating the encryption key using the VLAN name corresponding to the VLAN, it is easy for maintenance personnel to manage, and it is easy to generate various types of encryption keys from the same VLAN name using the priority bit of the VLAN tag. It becomes. In addition, it is possible to improve the security by changing the VLAN name at a predetermined time interval and generating and updating the corresponding encryption key. In addition, when the new key memory and the old key memory are provided in the IPsec gateway and decryption is impossible due to the mismatch of the encryption key between the transmission side and the reception side, by using the encryption key of the previous distribution held in the old key memory, The receiving side can be decrypted. If decryption is not possible, the recently distributed encryption key held in the key distribution data table of the monitoring control server is read and distributed to the transmission side, so that the encryption key on the transmission / reception side can be matched. Further, by adding the time information for validating the encryption key and distributing it, it is possible to avoid the problem that the encryption keys on the transmission / reception side do not match.

  The encryption communication system of the present invention will be described with reference to FIG. 1. An encryption key corresponding to a VLAN is connected to IPsec gateways 2-1 and 2-2 connected with a single or a plurality of terminals 1-1 to 1-9. In the encryption communication system including the monitoring control server 4 that distributes the VLAN, the monitoring control server 4 manages the VLAN name corresponding to the VLAN or a part of the VLAN name as a VLAN compatible encryption key, and uses this encryption key. A means for distributing the VLAN name corresponding to the VLAN to the IPsec gateways 2-1 and 2-2 and updating the VLAN name at predetermined time intervals is provided.

  The encryption key update method of the present invention distributes a VLAN-compatible encryption key from the monitoring control server 4 to the IPsec gateways 2-1 and 2-2 connected to a single or a plurality of terminals 1-1 to 1-9. In the encryption key update method for performing encrypted communication, the monitoring control server 4 distributes the VLAN name corresponding to the VLAN or a part of the VLAN name to the IPsec gateways 2-1 and 2-2 as the encryption key corresponding to the VLAN. The VLAN name is changed at predetermined time intervals, and the VLAN name is changed to change the encryption key corresponding to the VLAN and distribute it to the IPsec gateways 2-1 and 2-2.

  FIG. 1 is an explanatory diagram of Embodiment 1 of the present invention, in which 1-1 to 1-9 are terminals, 2-1 and 2-2 are IPsec gateways, 3 is a network, and 4 is a monitoring control server. The monitoring control server 4 has a function of generating and transmitting an encryption key corresponding to the VLAN group and a function of performing encryption key update processing to the IPsec gateways 2-1 and 2-2. The same VLAN ID: 3 is assigned to the monitoring control server 4 and the IPsec gateway 2-1-2-2 to configure a VLAN. Accordingly, the monitoring control server 4 and the IPsec gateways 2-1 and 2-2 can communicate with each other through the dotted line path, and the encryption key is distributed while maintaining confidentiality. The configuration in which the VLAN IDs of the terminals connected via the IPsec gateways 2-1 and 2-2 are the same and are in the same group is the same as the conventional one.

  The monitoring control server 4 manages each VLAN ID and encryption key by a virtual database MIB (Management Information Base) (not shown). When the number of VLAN groups becomes large, different encryption keys are generated. Therefore, the process of allocation becomes complicated. Therefore, it is generated using the VLAN name. Alternatively, a plurality of types of encryption keys can be generated using the VLAN name and the priority bit of the VLAN tag. As described above, the use of the VLAN name has an advantage that management by a maintenance person or the like is facilitated as compared with the case of managing the encryption key by enumerating numbers.

  FIG. 2 is an explanatory diagram of a frame configuration, where DstMAC indicates a reception MAC address, SrcMAC indicates a transmission MAC address, and VLANTag indicates a VLAN tag. The VLAN tag includes a type value Type, a priority bit Priority bit, and CFI (Canonical Format Indicator). And a VID (Virtual Local Area Network Identifier). Further, after the VLAN tag, there is a frame configuration in which Type, IPHeader, IPsecHeader, IPsecPayload, and Ethernet (registered trademark) Trailer are added.

  Therefore, when the VLAN name is shown in FIG. 3A, the entire VLAN name including vlanid 101 indicated by the dotted line or the VLAN ID excluding vlanid 101 is used as the encryption key. The encryption key can be updated by changing the VALN name. A part of the encryption key is used. In this case, the VLAN name corresponding to the VLAN ID stored in the MIB can be used. The VLAN name is changed at a predetermined time interval, and the monitoring control server 4 changes to the IPsec gateways 2-1 and 2-1. -2 can be distributed. The VLAN tag (VLAN tag) has eight priority values as shown in Priority bits 0 to 7, and the VLAN ID (VID) is one of 0 to 4095. Therefore, 32,752 different encryption keys can be generated from 1 to 4094 excluding 0 and 4095 of the VLAN ID and 8 types of priority values. For example, as shown in FIG. 3B, for the priority value 0, “vlanid101: 1230dfghjk” is the encryption key from the top, and for the priority value 1, the next “lcvbnm, ert3tfvgbhnjm” is the encryption key. Can do. In this way, different encryption keys can be generated from the same VLAN name. It should be noted that the cutout ranges can partially overlap each other.

  FIG. 4 shows an encryption key distribution sequence from the monitoring control server to the IPsec gateway, and shows a case where SNMP (Simple Network Management Protocol) is used. The SNMP includes basic commands Get Request, Get Next Request, Get Response, Set Request, and Trap. From the monitoring control server to the IPsec gateway, that is, from the monitoring control server 4 to the IPsec gateway 2 in FIG. The encryption key generated based on the VLAN name as described above is transmitted (SET) to -1 and 2-2. The IPsec gateway changes the stored encryption key to use the received encryption key, and transmits the changed data to the monitoring control server (GET Response).

  FIG. 5 is an explanatory diagram of a sequence when an encryption key is transmitted from the monitoring control server to the IPsec gateway using FTP (File Transfer Protocol). From the monitoring control server, commands 1, 2, 3,. The file is transmitted by FTP to the IPsec gateway. The IPsec gateway updates MIB (Management Information Base) according to CLI (Command Line Interface) in the file. In this case, the IPsec gateway updates the data of the MIB VLAN name by sending a file describing the CLI for changing the VLAN name of the VLAN ID to the IPsec gateway by FTP.

  In addition, for example, when using in-band, encryption key distribution and renewal processing uses the same transmission network as user data. Therefore, an in-band VLAN is set up between the IPsec gateway and the monitoring control server. Further, the above-described encryption key is encrypted with the VLAN name of the in-band VLAN as a common key and distributed from the monitoring control server to the IPsec gateway. Thereby, security in the distribution of the encryption key from the monitoring control server can be maintained.

  Also, the encryption key can be distributed between the IPsec gateway and the monitoring control server by out-band communication using a network different from the user data transmission network by the out-band port. Depending on the terminal, a VLAN tag may not be attached, and the IPsec gateway can deal with such a terminal by assigning a port VLAN and assigning an encryption key corresponding to the port VLAN.

  6, 7 and 8 are explanatory diagrams of the second embodiment of the present invention based on the network configuration and sequence, and show the case of updating the encryption key. 6A shows an example of a network configuration, and FIGS. 6B to 6D show sequences between IPsec GW1 and IPsec GW2. 6A, the same reference numerals as those in FIG. 1 denote the same parts. When the monitoring control server 4 and the IPsec gateways 2-1 and 2-2 have the same VLAN ID: 3 as shown in FIG. 1, and the terminals also have the same VLAN ID: 1000 and VLAN ID: 2000. Indicates.

  In FIG. 6B, the same encryption key indicated as “key2000.n” is distributed and held from the monitoring control server (not shown) with IPsecGW1 as the transmission side and IPsecGW2 as the reception side. In this case, when the data is transmitted after being encrypted with the encryption key, the receiving side holds the same encryption key as that of the transmitting side, so that it can be decrypted (decryption OK). When the transmitting side subsequently updates the encryption key to “key2000.n + 1” and encrypts and transmits with this key, as shown in the new key exchange, the receiving side transmits the encryption key “key2000.n before the new key exchange”. "Is held, it is impossible to decrypt (decryption NG) because the encryption key is different. The encryption key can be generated based on the VLAN name in the first embodiment.

  In FIG. 6C, when the receiving side receives the data encrypted with the encryption key “key2000.n”, the transmitting side and the receiving side hold the same encryption key and can be decrypted. (Decryption OK). However, after that, as shown as a new key exchange, the encryption key on the reception side is updated to “key2000.n + 1”, and the transmission side holds the previous encryption key in the state of holding the previous encryption key. When the data encrypted with the previous encryption key “key2000.n” is transmitted, the receiving side cannot decrypt with the updated encryption key (decryption NG). In FIG. 6D, after the encrypted data from the transmission side can be received and decrypted by the reception side (decryption OK), the transmission side shows as a new key exchange. When the encryption key is updated to “key2000.n + 1” and the reception side holds the previous encryption key, when the transmission side encrypts and sends a reply, the transmission side has already updated the encryption key. Since the key is held, decryption is impossible (decryption NG).

  In (E) of FIG. 7, the receiving side updates the encryption key to “key2000.n + 1” as shown as a new key exchange, and updates it from the receiving side when the transmitting side does not update the encryption key. The reply data encrypted with the encrypted key “key2000.n + 1” cannot be decrypted (decrypted NG) on the transmission side.

  Therefore, when the encryption key is updated, the old encryption key is also retained. That is, as shown in FIG. 7F, the transmission side and the reception side hold the new key and the old key. For example, if the new key “key2000.n” and the old key “key2000.n-1” are held and the transmitting side encrypts and transmits with the new key “key2000.n”, the receiving side can decrypt with the new key. (Decryption OK). Then, as shown in the new key exchange, the transmission side holds the old key “key2000.n” when it is updated to the new key “key2000.n + 1”. When the new key is transmitted after being encrypted, the new key “key2000.n + 1” is not held on the receiving side, so that decryption becomes impossible (decryption NG), and a key mismatch notification is sent to the transmitting side. This key mismatch notification can be transmitted in plain text. The transmission side determines that the encryption key on the reception side has not been updated to the new key, encrypts it with the stored old key “key2000.n”, and retransmits it. As a result, the receiving side can perform decoding (decoding OK).

  Also, in FIG. 7G, when the encryption key is updated on the transmission side, as shown in the new key exchange on the reception side, the new key “key2000.n + 1” is updated. The later received data cannot be decrypted with the new key (decryption NG). Therefore, the receiving side performs the decryption process again with the old key “key2000.n” held. As a result, decoding becomes possible (decoding OK). In other words, when the encryption key is updated from the monitoring control server, there is a situation where the transmission side and the reception side are not simultaneously in time. If the old key is decrypted and a key mismatch notification is received, it is retransmitted after being encrypted with the old key held.

  In FIG. 7H, since the encryption side is not updated on the receiving side where communication abnormality has occurred with the monitoring control server, for example, the transmitting side performs new key exchange twice. In this case, the transmitting side holds the new key “key2000.n + 2” and the old key “key2000.n + 1”, and the receiving side holds the new key “key2000.n” and the old key “key2000.n”. -1 "is held. In such a state, even if the receiving side makes a retransmission request by a key mismatch notification, the receiving side becomes impossible to decrypt (decryption NG) because the encryption keys do not match. In such a state, encrypted communication can be continued by the processing described below.

  That is, as shown in (I) of FIG. 8, in the transmission side IPsec GW1, the monitoring control server, and the reception side IPsec GW2, the transmission side inquires of the reception side encryption key to the monitoring control server. . The monitoring control server transmits the latest encryption key “key2000.n + 2” to the receiving side and notifies the transmitting side of the information on the new key. The receiving side holds the new key “key2000.n + 2” and the old key “key2000.n”, and the transmitting side encrypts and transmits with the new key “key2000.n + 2”. Since the receiving side holds the new key “key2000.n + 2”, decryption is possible (decryption is OK). If the monitoring control server holds the encryption key update history, the last distributed encryption key from the monitoring control server to the receiving side is sent to the transmitting side in response to a key inquiry from the transmitting side to the receiving side. Notification is performed, and the transmission side encrypts the data with the encryption key and transmits the encrypted data, so that the reception side can be decrypted (decryption OK).

  (J) in FIG. 8 shows a case where time information is added to the encryption key for distribution, and the encryption key is made valid after the time indicated by the time information. In the IPsec gateway, time information is added to each of the new key and the old key and held. Thereby, the transmission side and the reception side can recognize the currently valid encryption key and perform encrypted communication even if there is a difference in the actual distribution time of the encryption key.

  FIG. 9 shows a configuration in which a memory for storing new and old key information is provided in the IPsec gateway, and other processing means can apply a known configuration, and are not shown in the figure. . New key memories 11-1 and 11-2 and old key memories 12-1 and 12-2 are provided in the IPsec gateways 2-1 and 2-2, respectively. By periodically distributing new keys from the monitoring server 4, the encryption keys held in the new key memories 11-1 and 11-2 are moved to the old key memories 12-1 and 12-2, and the distributed new keys are transferred. And stored in the new key memories 11-1 and 11-2. As a result, in the case of the key mismatch described with reference to FIGS. 7F and 7G, the old key stored in the old key memory 12-1 or the old key memory 12-2 is used for encryption or Decryption enables encrypted communication between each other.

  FIG. 10 shows that the key distribution data table 10 is provided in the supervisory control server 4, the IPsec gateway 2-1 is A, the IPsec gateway 2-2 is B, and the new key memory 11-1 and the old key memory are stored in the IPsec gateway A. 12-1 and spare memory 13 are provided, and IPsec gateway B is provided with new key memory 11-2 and old key memory 12-2. Note that the IPsec gateway B can also be provided with a spare memory. Further, the other processing means can apply a known configuration and is not shown. The key distribution data table 10 provided in the monitoring control server 4 holds recently distributed encryption keys corresponding to the IPsec gateways A, B, C,.

  With this configuration, as shown in (I) of FIG. 8, when a key inquiry is made to the monitoring control server by the key mismatch notification from the transmitting side IPsec gateway A, the monitoring control server 4 The encryption key distributed to the IPsec gateway B on the receiving side forming the VLAN with the IPsec gateway A is read and distributed. In the illustrated key distribution data table 10, for example, the encryption key “yyyyyyyyyy” distributed to the IPsec gateway B is recorded. This encryption key is read out and notified to the IPsec gateway A on the transmission side. The IPsec gateway A holds the notified encryption key “yyyyyyyyyy” in the spare memory 13 and performs encrypted communication using the encryption key. At this time, since the encryption key “yyyyyyyyyy” is held in the new key memory 11-2 of the IPsec gateway B on the receiving side, it can be decrypted.

  FIG. 11 shows a flowchart for receiving a new key for an encryption key. Whether or not data has been encrypted and transmitted with the new key held in the new key memory by the new key exchange from the monitoring control server, and decrypted on the receiving side. Is determined (a1). That is, it is determined whether or not a mismatch notification is received from the receiving side. If no mismatch notification is received, the encrypted communication is successful and the process ends. If a mismatch notification is received, the encrypted communication is unsuccessful. In this case, since the encryption key does not match, the encrypted key is transmitted using the old key stored in the old key memory, and the mismatch notification is received. It is determined whether or not (a2). If no mismatch notification is received, the encrypted communication is successful and the process ends. When a mismatch notification is received, an inquiry about the opposite key, that is, the encryption key on the receiving side is made to the monitoring control server (a3).

  The monitoring control server searches the key distribution data table 10 shown in FIG. 10 to read and notify the latest distribution encryption key for the inquired IPsec gateway. The distributed encryption key is received, stored in the spare memory 13 (see FIG. 10) as a counter key (a4), encrypted with the counter key, and transmitted (a5). As a result, the encryption keys on the transmitting and receiving sides can be matched to make encrypted communication successful. That is, it is possible to solve the problem due to the encryption key mismatch. As shown in (I) of FIG. 8, in response to a key inquiry from the transmission side, the monitoring control server distributes the same latest key as that of the transmission side to the reception side, It is also possible to perform the process of matching the encryption keys.

  FIG. 12 shows a flowchart when distributing with the time code added to the encryption key. As shown in FIG. 8J, the encryption key with the time code (time information) added from the monitoring control server is shown. Distribute to the IPsec gateway. The IPsec gateway includes new key memories 11-1 and 11-2 and old key memories 12-1 and 12-2 shown in FIG. 9 or FIG. 10, and the distributed new key is used as the new key memory 11-1. 11-2 are held together with the time code, and the previous new key is held together with the time code in the old key memories 12-1 and 12-2 (b1).

  Then, the current time is compared with the time code added to the new key (b2). If the current time is not based on the time code added to the new key, that is, if the time code is newer, encrypted communication is performed with the old key (b3), and the current time is set to the time code time. If it has passed, that is, if the time code is older, encrypted communication is performed with the new key (b4). Even when this time code is added to the encryption key and distributed, if encrypted communication with the new key between the sending side and the receiving side is not possible due to some kind of failure, encrypted communication is performed using the old key. When encrypted communication cannot be performed, a key mismatch notification is sent to the monitoring control server, the key distribution data table 10 (see FIG. 10) of the monitoring control server is searched, and the encryption keys of the transmitting side and the receiving side are matched. It can be performed.

It is processing explanatory drawing of Example 1 of this invention. It is frame structure explanatory drawing. It is explanatory drawing of encryption key generation. It is a delivery sequence explanatory drawing of an encryption key. It is a delivery sequence explanatory diagram of the encryption key It is sequence explanatory drawing in Example 2 of this invention. It is sequence explanatory drawing in Example 2 of this invention. It is sequence explanatory drawing in Example 2 of this invention. It is principal part explanatory drawing of Example 2 of this invention. It is principal part explanatory drawing of Example 2 of this invention. It is a flowchart of new key reception. It is a flowchart by time code addition. It is explanatory drawing of a network system.

Explanation of symbols

1-1 to 1-9 Terminals 2-1 and 2-2 IPsec Gateway 3 Network 4 Monitoring and Control Server 10 Key Distribution Database 11-1 and 11-2 New Key Memory 12-1 and 12-2 Old Key Memory 13 Spare Memory

Claims (13)

In an encryption communication system including a monitoring control server that distributes a VLAN-compatible encryption key to an IPsec gateway to which a single or a plurality of terminals are connected,
The monitoring control server includes means for managing the VLAN name corresponding to the VLAN or a part of the VLAN name as an encryption key corresponding to the VLAN, and distributing the encryption key to the IPsec gateway. Encrypted communication system.   2. The monitoring control server includes means for extracting, managing, and distributing the encryption key by extracting a VLAN name corresponding to a VLAN ID according to a type corresponding to a priority bit of a VLAN tag. The encryption communication system described.   3. The encryption communication system according to claim 1, wherein the monitoring control server includes means for changing the VLAN name corresponding to the VLAN ID at a predetermined time interval to generate the encryption key. .   4. The encryption communication system according to claim 1, wherein the monitoring control server includes means for distributing the encryption key via an out-band port of the IPsec gateway.   The monitoring control server includes means for configuring an in-band VLAN with the IPsec gateway, and encrypting and distributing the encryption key by the in-band VLAN using the in-band VLAN name as a common key. The encrypted communication system according to any one of claims 1 to 3, characterized in that: In an encryption communication system including a monitoring control server that distributes a VLAN-compatible encryption key to an IPsec gateway to which a single or a plurality of terminals are connected,
The monitoring control server includes means for managing and distributing the VLAN-compatible encryption key distributed to the IPsec gateway,
The IPsec gateway includes a new key memory that holds the currently distributed encryption key from the monitoring control server as a new key, an old key memory that holds the previously distributed encryption key as an old key, and encrypted communication using the new key. And a means for switching to encrypted communication using the old key held in the old key memory due to unsuccessful communication.   The monitoring control server includes a key distribution data table for holding an encryption key distributed to the IPsec gateway and a key distribution data table for the IPsec gateway, and an encryption key distributed to the receiving IPsec gateway by a key mismatch notification from the transmitting IPsec gateway. Is read out from the key distribution data table and distributed to the IPsec gateway on the transmission side, and the IPsec gateway on the transmission side holds a reserved memory for holding the distributed encryption key and the reserved memory. The encrypted communication system according to claim 6, further comprising means for performing encrypted communication using the encrypted key.   The monitoring control server includes means for distributing the encryption key for the IPsec gateway by adding time information indicating a time at which the encryption key is valid, and the IPsec gateway is configured such that a current time is a time according to the time information. The encrypted communication system according to claim 6 or 7, further comprising means for performing cryptographic communication using the encryption key when a period of time has passed. In an encryption key update method for performing encrypted communication by distributing a VLAN-compatible encryption key from a monitoring control server to an IPsec gateway to which a single or a plurality of terminals are connected,
The monitoring control server distributes the VLAN name corresponding to the VLAN or a part of the VLAN name to the IPsec gateway as the encryption key corresponding to the VLAN, changes the VLAN name at a predetermined time interval, and sets the VLAN name. A method for updating the encryption key, comprising: changing the encryption key corresponding to the VLAN by changing the method and distributing the encryption key to the IPsec gateway.   10. The monitoring control server includes a step of extracting, managing, and distributing the encryption key by extracting a VLAN name corresponding to a VLAN ID according to a type corresponding to a priority bit of a VLAN tag. Encryption key update method. In an encryption key update method for performing encrypted communication by distributing a VLAN-compatible encryption key from a monitoring control server to an IPsec gateway to which a single or a plurality of terminals are connected,
The IPsec gateway includes a new key memory that holds the currently distributed encryption key from the monitoring control server as a new key, and an old key memory that holds the previously distributed encryption key as an old key, When it cannot be decrypted with the new key encryption key held in the new key memory in the gateway, it is decrypted with the old key encryption key held in the old key memory, and the encryption key between the new key and the old key is decrypted. If decryption is not possible, a key mismatch notification is sent to the IPsec gateway on the transmission side, and the transmission side IPsec gateway includes a process of encrypting and retransmitting with the encryption key of the old key held in the old key memory An encryption key update method characterized by the above.   The monitoring control server includes a key distribution data table that holds the encryption key distributed to the IPsec gateway in correspondence with the IPsec gateway, and receives a key mismatch notification from the transmission side IPsec gateway in response to the encryption key update, thereby receiving the IPsec of the reception side. The encryption key distributed to the gateway is read from the key distribution data table and distributed to the IPsec gateway on the transmission side, and the IPsec gateway on the transmission side includes a spare memory for holding the distributed encryption key, 12. The encryption key update method according to claim 11, further comprising a step of performing encrypted communication using an encryption key held in a memory.   The monitoring control server distributes the encryption key updated at a predetermined time interval with respect to the IPsec gateway by adding time information for validating the encryption key, and the IPsec gateway transmits the current time according to the time information. 12. The method for updating an encryption key according to claim 11, further comprising a step of performing encryption communication using the encryption key when a period of time has passed.

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