JP5645990B2 - Communication system and communication method - Google Patents

Description

  The present invention relates to a communication system and a communication method. The present invention includes, for example, a communication device used in a system that handles confidential information that should not be leaked to the outside, such as a device that conceals communication, and a management device that manages those communication devices, and those The present invention relates to a method for managing communication devices.

  In recent years, many systems have been developed that handle confidential information inside a device (communication device) that conceals communication contents between devices (for example, see Patent Document 1). These devices store confidential information within them. Many systems include devices (management devices) that manage these devices. A special communication (management communication) for management is performed between the management device and the communication device.

  Management communication periodically updates information (eg, key data) necessary for the confidentiality function of each communication device from the management device and confirms that the communication device itself has not been stolen. Or to check whether the communication device has been spoofed by another device.

JP 2005-251081 A

  In the prior art, since management communication for each communication device is individually activated as described above, the management device needs to have high processing performance in order to manage a large number of communication devices. For this reason, when there are a large number of communication devices included in the system, the performance of one management device is insufficient, and it is necessary to install a plurality of management devices, resulting in a large system construction cost. Further, when a communication device is added under the management device, complicated work such as manually setting information of the communication device to be added to the management device has occurred at the addition timing.

  For example, an object of the present invention is to provide a communication system that does not need to significantly improve the performance of a management device that manages communication devices even when the number of communication devices increases.

  A communication system according to an aspect of the present invention includes a plurality of communication devices and a management device that manages connection states of the plurality of communication devices. The management device transmits management data to at least one communication device of the plurality of communication devices. The plurality of communication devices, in order from the communication device that has received the management data, transmit the management data to at least one other communication device that has not received the management data, and receive the management data When there are no communication devices left, the management data is transmitted to the management device. The management device determines that the plurality of communication devices are normally connected when the management data is received.

  In the communication system according to one aspect of the present invention, if the management device transmits management data to at least one of the plurality of communication devices, then the management data is received from any of the communication devices. At this point, it can be determined that the plurality of communication devices are normally connected. Therefore, even if the number of communication devices increases, it is not necessary to significantly improve the performance of the management device, and an increase in cost can be suppressed.

1 is a block diagram showing a configuration of a communication system according to Embodiments 1 to 4. FIG. The figure which shows the structural example of the management data which concern on Embodiment 1-4. The figure which shows the structural example of the message part of the management data which concerns on Embodiment 1-4. The figure which shows the structural example of the acknowledge which concerns on Embodiment 1-4. FIG. 6 is a block diagram illustrating a configuration of a communication system according to a fifth embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing a configuration of a communication system 10 according to the present embodiment.

  In FIG. 1, the communication system 10 includes a plurality of communication devices 20, a management device 30 that manages a connection state of the plurality of communication devices 20, and individual public keys of the communication devices 20 and the management devices 30. And a public key server 40 stored (stored) and provided by a storage device.

  The communication device 20 stores (holds) the individual secret key paired with the public key stored in the public key server 40 by the storage device. Further, the communication device 20 stores confidential information that should not be leaked outside by a storage device.

  Similar to the communication device 20, the management device 30 stores (holds) an individual secret key that is paired with the public key stored in the public key server 40 using the storage device.

  The communication system 10 sequentially transmits management communication from the management device 30 to the communication device 20 between the communication devices 20. Management communication that the management device 30 starts for management is transferred serially between the communication devices 20, and the result is returned to the management device 30 to verify whether each communication device 20 is located or spoofed. By doing so, it is possible to reduce the load on the management device 30 by consolidating the management communication that has conventionally been individually activated in each communication device 20 into one management communication. Therefore, even if the number of communication devices 20 managed by the management device 30 increases, the performance required for the management device 30 can be suppressed. Therefore, the management device 30 is a low-cost server (for example, inexpensive) that does not have high performance. PC (Personal Computer) server equipped with a central CPU (Central Processing Unit) can be employed. Or since the number of the management apparatuses 30 can be suppressed, the construction cost of the communication system 10 can be suppressed at low cost.

  In the management communication, the management data 50 is transmitted (transferred) from the management device 30 to the communication device 20 having the minimum management number “1” (hereinafter referred to as the first communication device 20). An acknowledge 60 is returned (returned) to 30 as a response to the management data 50. Next, the management data 50 is transmitted from the first communication device 20 to the communication device 20 having the second smallest management number “2” (hereinafter, the second communication device 20). The acknowledgment 60 is returned to the first communication device 20. Thereafter, similarly, the transmission of the management data 50 and the reply of the acknowledge 60 are sequentially performed. Finally, the management data 50 is transmitted from the communication device 20 having the maximum management number “n” (hereinafter referred to as the nth communication device 20) to the management device 30, and the acknowledge 60 is transmitted from the management device 30 to the nth communication device 20. Is replied.

  Each communication device 20 and management device 30 encrypts the management data 50 with the transmission destination public key stored in the public key server 40 when transmitting the management data 50. When receiving the management data 50, each communication device 20 and management device 30 decrypts the management data 50 with its own private key and confirms the contents. If there is no problem in the contents of the management data 50, each communication device 20 and management device 30 returns an acknowledge 60. When each of the communication device 20 and the management device 30 returns the acknowledge 60, the communication device 20 and the management device 30 encrypt the acknowledge 60 with the public key of the reply destination (the transmission source of the management data 50) stored in the public key server 40. When the communication device 20 and the management device 30 receive the acknowledge 60, the communication device 20 and the management device 30 decrypt the acknowledge 60 with their own secret key and confirm the contents. If there is a problem with the contents of the acknowledge 60, each of the communication devices 20 and the management device 30 determines that the acknowledge 60 has not been received correctly. Also, each communication device 20 and management device 30 determines that the acknowledge 60 could not be received correctly even if the acknowledge 60 was not received within a predetermined time after transmitting the management data 50.

  If each communication device 20 cannot correctly receive the acknowledge 60 from the next communication device 20 in the transmission of the management communication to the next communication device 20, an abnormality has occurred in the next communication device 20, or The management device 30 is notified that there is a possibility of being stolen. As described above, when the communication device 20 is stolen, the communication device 20 having the management number immediately before the management communication is started for the stolen communication device 20 is sent to the management device 30. By notifying the absence, the management device 30 can easily detect the theft and can take measures against leakage of confidential information, so that damage can be minimized.

  In the management data 50 to be included in the management communication, an area to be written for each communication device 20 is determined, and in addition to this, a spare area for the addition of the communication device 20 is provided. In the expansion work of the communication device 20, the management number “n + 1” obtained by adding 1 to the maximum management number “n” before the expansion is set in the communication device 20 to be added and then added to the communication system 10. The management data 50 is automatically transmitted to the communication device 20 having the maximum management number “n + 1” after the expansion by the communication device 20 having the maximum management number “n” before the expansion. Can participate in management communication, and expansion work is simplified.

  FIG. 2 is a diagram illustrating a configuration example of the management data 50.

  In FIG. 2, the management data 50 includes a message part 51 and a verification code part 52.

  When the management data 50 is transmitted from the management device 30 to the first communication device 20, the management device 30 performs a hash operation process on the message unit 51, and encrypts the obtained hash value with the secret key of the management device 30. Processing is performed, and the obtained encrypted data is added as the verification code section 52.

  When n is the number of communication devices 20, i = 1, 2,..., n, the management data 50 changes from the i-th communication device 20 to the (i + 1) -th communication device 20 (if i = n, the management device 30). In the i-th communication device 20, the message unit 51 is subjected to hash calculation processing, and the obtained hash value is subjected to cryptographic processing using the secret key of the i-th communication device 20 to obtain The encrypted data thus added is added as the verification code section 52.

  The apparatus that has received the management data 50 decrypts the verification code part 52 of the management data 50 with the public key of the transmission source of the management data 50 and applies a hash calculation process to the message part 51 of the management data 50 to obtain the obtained hash The management data 50 can be verified by comparing the value with the data obtained by decoding.

  FIG. 3 is a diagram illustrating a configuration example of the message unit 51 of the management data 50.

  In FIG. 3, the message part 51 of the management data 50 is configured by combining message data (common key, health check command, etc.) for each communication device 20 by the number of communication devices 20 managed by the management device 30. Has been. In the message unit 51, when the communication device 20 is added, a spare message area is used as an area for writing message data (notification of newly joining management communication, etc.) from the added communication device 20 to the management device 30. Is also provided.

  FIG. 4 is a diagram illustrating a configuration example of the acknowledge 60.

  In FIG. 4, the acknowledge 60 includes an acknowledge data portion 61 and a verification code portion 62.

  When n is the number of communication devices 20, i = 1, 2,..., n, the acknowledge 60 changes from the i-th communication device 20 to the i-1th communication device 20 (if i = 1, the management device) 30), the i-th communication device 20 performs a hash calculation process on the acknowledge data unit 61, and the obtained hash value is subjected to an encryption process using the secret key of the i-th communication device 20, The obtained encrypted data is added as the verification code part 62.

  Even when the acknowledge 60 is transmitted from the management device 30 to the nth communication device 20, the management device 30 performs the hash calculation process on the acknowledge data unit 61, and the obtained hash value is used with the secret key of the management device 30. Cryptographic processing is performed, and the obtained encrypted data is added as a verification code section 62.

  The device that has received the acknowledge 60 decrypts the verification code part 62 of the acknowledge 60 with the public key of the transmission source of the acknowledge 60, performs a hash operation process on the acknowledge data part 61 of the acknowledge 60, and the obtained hash value, The acknowledgment 60 can be verified by comparing the data obtained by decoding.

  The acknowledge data section 61 may be meaningless dummy data, but it is also possible to write meaningful data depending on the application of the communication system 10.

  Hereinafter, an example of the operation of the communication system 10 (the communication method according to the present embodiment) will be described.

  The first to n communication devices 20 managed by the management device 30 store in advance a secret key that only the communication device 20 has. The management device 30 and the first to n-th communication devices 20 acquire each other's public key from the public key server 40 in advance. In addition, the management device 30 and the first to nth communication devices 20 also acquire a communication address (for example, an IP (Internet Protocol) address) in advance from a publicly disclosed server or the like.

  First, the management device 30 generates a message unit 51 that includes data such as a common key and a health check command that need to be received by each communication device 20 as message data for each communication device 20. The management apparatus 30 generates a verification code part 52 including a verification code for the entire message part 51 using the secret key of the management apparatus 30. The management device 30 transmits management data 50 in which the verification code unit 52 is added to the message unit 51 to the first communication device 20. The message data (common key, health check command, etc.) for each communication device 20 is concealed by encrypting it using the public key of each communication device 20 so that only the communication device 20 can decrypt it. May be.

  When the first communication device 20 receives the management data 50 from the management device 30, the first communication device 20 verifies that the management data 50 is transmitted from the management device 30 (is not spoofed), and verifies If there is no problem in the result, an acknowledge 60 is transmitted to the management apparatus 30.

  The management device 30 verifies that the acknowledge 60 transmitted from the first communication device 20 is transmitted from the first communication device 20 (not impersonated). When the verification fails, the management device 30 warns the operator that the first communication device 20 may be spoofed. If the acknowledge 60 is not transmitted within the specified time, the management device 30 warns the operator that the first communication device 20 may be broken or stolen.

  The first communication device 20 performs necessary processing using the management data 50 received from the management device 30. When the common key is included in the message part 51 of the management data 50, the first communication device 20 stores the common key in a storage device or executes cryptographic processing using the common key. . When the health check command is included in the message part 51 of the management data 50, the first communication device 20 executes the health check process of the first communication device 20. The first communication device 20 writes the processing result in the message part 51 of the management data 50 as message data from the first communication device 20 to the management device 30. The first communication device 20 uses the private key of the first communication device 20 to generate a verification code unit 52 that includes a verification code for the entire message unit 51. The first communication device 20 transmits management data 50 in which the verification code unit 52 is added to the message unit 51 to the second communication device 20.

  When the second communication device 20 receives the management data 50 from the first communication device 20, the management data 50 is transmitted from the first communication device 20 (not impersonated). If there is no problem in the verification result, an acknowledge 60 is transmitted to the first communication device 20.

  The first communication device 20 verifies that the acknowledge 60 transmitted from the second communication device 20 is transmitted from the second communication device 20 (not impersonated). When the verification fails, the first communication device 20 notifies the management device 30 that the second communication device 20 may be spoofed. Further, if the acknowledge 60 is not transmitted within the specified time, the first communication device 20 notifies the management device 30 that the second communication device 20 may be broken or stolen. To do. When receiving the notification from the first communication device 20, the management device 30 warns the operator of the content of the notification.

  Thereafter, the management data 50 is sequentially transmitted from the second communication device 20 to the third communication device 20 (if any) and from the third communication device 20 to the fourth communication device 20 (if any). Is done. Each communication device 20 writes the processing result based on the management data 50 in the message section 51 of the management data 50 and transmits the management data 50 to the next communication device 20. However, the nth communication device 20 which is the last communication device 20 transmits the management data 50 to the management device 30 instead of the other communication devices 20.

  Upon receiving the management data 50 from the nth communication device 20, the management device 30 verifies that the management data 50 has been transmitted from the nth communication device 20 (not spoofed). If there is no problem in the verification result, an acknowledge 60 is transmitted to the nth communication device 20. Further, the management device 30 confirms that the processing result of each communication device 20 written in the message part 51 of the management data 50 is normal, so that the n number of communication devices 20 are operating and have failed. Can be confirmed that it has not been stolen or stolen.

  Here, it is assumed that public keys for the number of communication devices 20 that are expected to be added are registered in the public key server 40 in advance. When the communication device 20 is added, at least the nth communication device 20 is notified in advance that the (n + 1) th communication device 20 will be added. The nth communication apparatus 20 that has received the notification transmits the management data 50 to the (n + 1) th communication apparatus 20 instead of the management apparatus 30. The (n + 1) th communication device 20 returns an acknowledge 60 to the nth communication device 20 and transmits management data 50 to the management device 30. At this time, the (n + 1) th communication device 20 writes the message data from the (n + 1) th communication device 20 to the management device 30 in a spare message area provided in the message section 51 of the management data 50 in advance. The management device 30 can read the content of the message data written by the (n + 1) th communication device 20 and recognize that the (n + 1) th communication device 20 has been installed.

  In the present embodiment, the management device 30 transmits the management data 50 to only one communication device 20 among the n communication devices 20, but the management device 30 as in the fifth embodiment to be described later. However, the management data 50 may be transmitted to two or more communication devices 20. That is, the management device 30 may transmit the management data 50 to at least one communication device 20 among the n communication devices 20.

  Further, in the present embodiment, the n communication devices 20 are managed in order from the communication device 20 that has received the management data 50 to only the other communication device 20 that has not received the management data 50. However, the n communication devices 20 transmit the management data 50 to the other two or more communication devices 20 that have not received the management data 50 in order from the communication device 20 that has received the management data 50. May be. That is, the n communication devices 20 may transmit the management data 50 to at least one other communication device 20 that has not received the management data 50 in order from the communication device 20 that has received the management data 50. In any case, at the time when there is no communication device 20 that has not received the management data 50, among the n communication devices 20, the communication device 20 that has not transmitted the management data 50 (to other communication devices 20). Transmits the management data 50 to the management apparatus 30. Thereby, the management apparatus 30 can determine that n communication apparatuses 20 are normally connected when the management data 50 is received.

Embodiment 2. FIG.
In the present embodiment, differences from the first embodiment will be mainly described.

  In the first embodiment, the order in which the n communication devices 20 should receive the management data 50 (hereinafter, the reception order of the management data 50) is determined in advance.

  On the other hand, in the present embodiment, the management device 30 repeatedly determines the reception order of the management data 50.

  In the present embodiment, every time the management device 30 determines the reception order of the management data 50, the management device 30 notifies the order to at least the first communication device 20 in the order. Then, the management device 30 transmits the management data 50 to the first communication device 20 in the order.

  The n communication devices 20 select the communication device 20 that is to receive the management data 50 next in order from the communication device 20 that has received the management data 50 according to the order notified by the management device 30, and the selected communication When the management data 50 is transmitted to the device 20 and there is no communication device 20 that has not received the management data 50, the management data 50 is transmitted to the management device 30. That is, the last communication device 20 in the order notified by the management device 30 transmits the management data 50 to the management device 30.

  The management device 30 determines that the n communication devices 20 are normally connected when the management data 50 is received. That is, every time the management device 30 determines the reception order of the management data 50, when the management data 50 is received from the last communication device 20 in the order, the n communication devices 20 are normally connected. Judge.

  In this embodiment, since the receiving order of the management data 50 is not fixed (that is, variable), spoofing due to replaying the management data 50 between any two communication devices 20 can be prevented.

  The management device 30 may determine the reception order of the management data 50 at regular time intervals (that is, periodically), may be determined according to a predetermined schedule, It may be determined when new data that needs to be received by the communication device 20 is input to the management device 30, or may be determined at random.

  Further, when determining the reception order of the management data 50, the management device 30 may select the reception order of the management data 50 from a plurality of predetermined candidates in order or randomly, or any arbitrary The reception order of the management data 50 may be created every time.

  Further, when the management device 30 notifies the communication device 20 of the reception order of the management data 50, communication data (for example, IP packets) for notifying the reception order of the management data 50 is separated from the management data 50. May be transmitted to the first communication device 20 in this order as the communication data, or may be simultaneously broadcast (broadcast) to the n communication devices 20, and the message data for notifying the reception order of the management data 50 may be managed. It may be included in the data 50 and transmitted to the first communication device 20 in the order.

  Further, when each communication device 20 cannot receive a valid acknowledge 60 from the next communication device 20, there is a possibility that the next communication device 20 has been spoofed or the next communication device 20 has failed. In addition to notifying the management device 30 that there is a possibility of being stolen, the management data 50 is transmitted to the next communication device 20 of the next communication device 20 according to the order notified by the management device 30. May be.

Embodiment 3 FIG.
The difference between the present embodiment and the second embodiment will be mainly described.

  In the second embodiment, the management device 30 determines the reception order of the management data 50 so that all the n communication devices 20 receive the management data 50.

  On the other hand, in the present embodiment, depending on the timing at which the management device 30 transmits the management data 50, the communication devices 20 other than some of the communication devices 20 among the n communication devices 20 receive the management data 50. In some cases, the receiving order of the management data 50 may be determined.

  In the present embodiment, the management device 30 includes all the n communication devices 20 in the reception order of the management data 50 according to the timing of transmitting the management data 50 before determining the reception order of the management data 50. Or whether only some of the n communication devices 20 are excluded. When determining that all of the n communication devices 20 are included in the reception order of the management data 50, the management device 30 sets the order in which the n communication devices 20 should receive the management data 50 as the reception order of the management data 50. decide. On the other hand, when it is determined that some communication devices 20 are excluded from the n communication devices 20 in the reception order of the management data 50, the management device 30 determines that some of the communication devices 20 among the n communication devices 20. The order in which the other communication devices 20 should receive the management data 50 is determined as the reception order of the management data 50. The management device 30 notifies the order to at least the first communication device 20 in the order. Then, the management device 30 transmits the management data 50 to the first communication device 20 in the order.

  Among the n communication devices 20, the communication devices 20 included in the reception order of the management data 50 are the management data next in order from the communication device 20 that has received the management data 50 according to the order notified by the management device 30. 50, the management data 50 is transmitted to the selected communication device 20, and when there is no communication device 20 that has not received the management data 50, the management data 50 is sent to the management device 30. Send. That is, the last communication device 20 in the order notified by the management device 30 transmits the management data 50 to the management device 30.

  As in the second embodiment, the management device 30 determines the reception order of the management data 50 every time it determines the reception order of the management data 50 and receives the management data 50 from the last communication device 20 in the order. It is determined that the included communication device 20 is normally connected.

  In the present embodiment, for example, when the management device 30 transmits the management data 50 at an interval of 5 minutes, only the communication device 20 that stores confidential information of high importance among the n communication devices 20 every time ( That is, the management data 50 is received (at 5 minute intervals), the connection state is confirmed, and the communication device 20 that stores confidential information of low importance is only once every 12 times (that is, at one hour intervals). It is possible to receive the management data 50 and confirm the connection state. Therefore, the frequency of confirmation of the connection state can be changed for each communication device 20 according to the importance of the information stored in the communication device 20, and the efficiency is improved.

Embodiment 4 FIG.
In the present embodiment, differences from the first embodiment will be mainly described.

  In the first embodiment, when each of the n communication devices 20 receives the management data 50, the management data 50 is confirmed to be correct or not. Acknowledge 60 is transmitted. When the management device 30 receives the acknowledge 60, the management device 30 confirms whether the acknowledge 60 is correct. In addition, when the management device 30 receives the management data 50, the management device 30 confirms whether the management data 50 is correct. Then, if the acknowledge 60 and the management data 50 are regular data, the management device 30 determines that n communication devices 20 are normally connected.

  On the other hand, in the present embodiment, when each of the n communication devices 20 receives the management data 50, the management data 50 is confirmed to be correct. If the management data 50 is regular data, the management data 50 is acknowledged. Management data 50 is transmitted with 60 added. When receiving the management data 50, the management device 30 confirms whether the management data 50 is correct. If the management data 50 is regular data and the acknowledge 60 is added to the management data 50, the management device 30 determines that the n communication devices 20 are normally connected.

  In the present embodiment, instead of causing each communication device 20 to verify the acknowledge 60 from the transmission destination of the management data 50, the management device 30 checks the acknowledge 60 of each communication device 20 in a lump to manage once. Communication time can be shortened.

Embodiment 5 FIG.
In the present embodiment, differences from the first embodiment will be mainly described.

  FIG. 5 is a block diagram showing a configuration of the communication system 10 according to the present embodiment.

  5, the communication system 10 includes a plurality of communication devices 20, a management device 30, and a public key server 40, as in the first embodiment shown in FIG.

  In the first embodiment, the management device 30 transmits management data 50 to the first communication device 20 among the n communication devices 20. After receiving the management data 50 from the management device 30, the first communication device 20 transmits the management data 50 to the second communication device 20 among the n communication devices 20. When i = 2, 3,..., n−1, the i-th communication device 20 among the n communication devices 20 is changed from the i-1th communication device 20 among the n communication devices 20. After receiving the management data 50, the management data 50 is transmitted to the (i + 1) th communication device 20 among the n communication devices 20. The nth communication device 20 among the n communication devices 20 receives the management data 50 from the n−1th communication device 20 among the n communication devices 20 and then transmits the management data 50 to the management device 30. To do.

  On the other hand, in the present embodiment, the management device 30 transmits the management data 50 not only to the first communication device 20 among the n communication devices 20 but also to the nth communication device 20. After receiving the management data 50 from the management device 30, the first communication device 20 transmits the management data 50 to the second communication device 20 among the n communication devices 20. After receiving the management data 50 from the management device 30, the nth communication device 20 transmits the management data 50 to the (n−1) th communication device 20 among the n communication devices 20. When i = 2, 3,..., n−1, the i-th communication device 20 among the n communication devices 20 is only the i−1-th communication device 20 among the n communication devices 20. When the management data 50 is received, the management data 50 is transmitted to the (i + 1) th communication device 20 among the n communication devices 20. When the i-th communication device 20 receives the management data 50 from only the i + 1-th communication device 20, the i-th communication device 20 transmits the management data 50 to the i-1-th communication device 20. When the i-th communication device 20 receives the management data 50 from the (i−1) -th communication device 20 and the (i + 1) -th communication device 20, the i-th communication device 20 transmits the management data 50 to the management device 30.

  In this embodiment, assuming that the direction of management communication (the direction in which management data 50 flows) in Embodiment 1 is the forward direction, the management communication is performed simultaneously in both the forward direction and the reverse direction. Can be reduced to about half.

  In the first to fifth embodiments described above, each of the plurality of communication devices 20 and management device 30 included in the communication system 10 is, for example, a computer, and hardware such as a processing device, a storage device, an input device, and an output device. Wear device. These hardware devices are connected by cables and signal lines.

  The processing device is, for example, a CPU, and via a bus, a ROM (Read / Only / Memory), a RAM (Random / Access / Memory), a communication board, a display device, a keyboard, a mouse, an HDD (Hard / Disk / Drive). , Connected to an SSD (Solid / State / Drive) or the like, and controls these hardware devices. The storage device is, for example, a volatile memory such as a RAM. The storage device is a non-volatile memory such as a ROM, HDD, or SSD. The input device is, for example, a communication board, a keyboard, or a mouse. The output device is, for example, a communication board or a display device.

  The communication board is connected to a network such as a LAN (Local Area Network), a WAN (Wide Area Area Network), or the Internet. Programs and files are stored in the HDD or SSD. The program is read and executed by the CPU. The file includes data, information, and signal values described as “˜data”, “˜information”, “˜ID (identifier)”, “˜flag”, and “˜result” in the description of the embodiment of the present invention. And variable values and parameters are included as items of “˜file”, “˜database”, and “˜table”. The “˜file”, “˜database”, and “˜table” are stored in the storage device. Data, information, signal values, variable values, and parameters stored in the storage device are read by the CPU via a read / write circuit, and are extracted, searched, referenced, compared, calculated, calculated, controlled, output, printed, displayed, etc. Used for CPU processing (operation).

  As mentioned above, although embodiment of this invention was described, you may implement in combination of 2 or more among these embodiment. Alternatively, one of these embodiments may be partially implemented. Alternatively, two or more of these embodiments may be partially combined. In addition, this invention is not limited to these embodiment, A various change is possible as needed.

  DESCRIPTION OF SYMBOLS 10 Communication system, 20 Communication apparatus, 30 Management apparatus, 40 Public key server, 50 Management data, 51 Message part, 52 Verification code part, 60 Acknowledge, 61 Acknowledge data part, 62 Verification code part

Claims (6)

A plurality of communication devices;
A management device for managing a connection state of the plurality of communication devices,
n is the number of the plurality of communication devices, i is an integer from 2 to n−1,
The management device transmits management data to a first communication device and an nth communication device among the plurality of communication devices;
After the first communication device receives the management data from the management device, the management device transmits the management data to a second communication device among the plurality of communication devices,
After the nth communication device receives the management data from the management device, the management data is transmitted to the n-1th communication device among the plurality of communication devices,
The communication device of the i among the plurality of communication devices, when receiving the management data from only the i-1 of the communication device of the plurality of communication devices, the (i + 1) among the plurality of communication devices And when the management data is received from only the (i + 1) th communication device among the plurality of communication devices, the i-1th communication device among the plurality of communication devices. The management data is transmitted, and when the management data is received from the i-1 th communication device and the i + 1 th communication device among the plurality of communication devices, the management data is transmitted to the management device,
A communication system, wherein the management device determines that the plurality of communication devices are normally connected when the management data is received. A plurality of communication devices;
A management device for managing a connection state of the plurality of communication devices,
The management device transmits management data to at least one communication device of the plurality of communication devices;
The plurality of communication devices sequentially transmit the management data to at least one other communication device that has not received the management data, and receive the management data from the communication device that has received the management data. When there are no communication devices left, the management data is transmitted to the management device,
When each of the plurality of communication devices receives the management data, it confirms whether the management data is correct or not, and if the management data is regular data, transmits an acknowledgment to the transmission source of the management data,
When the management device receives the acknowledge, it confirms whether the acknowledge is correct, and when the management data is received , confirms whether the management data is correct, and if the acknowledge and the management data are regular data, A communication system characterized by determining that a plurality of communication devices are normally connected. A plurality of communication devices;
A management device for managing a connection state of the plurality of communication devices,
The management device transmits management data to at least one communication device of the plurality of communication devices;
The plurality of communication devices sequentially transmit the management data to at least one other communication device that has not received the management data, and receive the management data from the communication device that has received the management data. When there are no communication devices left, the management data is transmitted to the management device,
When each of the plurality of communication devices receives the management data, the management data is confirmed to be correct or not. If the management data is regular data, an acknowledgment is added to the management data and the management data is added. Send
When the management device receives the management data, it confirms whether the management data is correct. If the management data is regular data and the acknowledge is added to the management data, the plurality of units A communication system characterized by determining that the communication device is normally connected. n is the number of communication devices, i is an integer from 2 to n-1,
The management device that manages the connection state of the plurality of communication devices transmits management data to the first communication device and the nth communication device among the plurality of communication devices,
After the first communication device receives the management data from the management device, the management device transmits the management data to a second communication device among the plurality of communication devices,
After the nth communication device receives the management data from the management device, the management data is transmitted to the n-1th communication device among the plurality of communication devices,
The communication device of the i among the plurality of communication devices, when receiving the management data from only the i-1 of the communication device of the plurality of communication devices, the (i + 1) among the plurality of communication devices And when the management data is received from only the (i + 1) th communication device among the plurality of communication devices, the i-1th communication device among the plurality of communication devices. The management data is transmitted, and when the management data is received from the i-1 th communication device and the i + 1 th communication device among the plurality of communication devices, the management data is transmitted to the management device,
A communication method, wherein the management device determines that the plurality of communication devices are normally connected when the management data is received. A management device that manages a connection state of a plurality of communication devices, transmits management data to at least one communication device among the plurality of communication devices;
The plurality of communication devices sequentially transmit the management data to at least one other communication device that has not received the management data, and receive the management data from the communication device that has received the management data. When there are no communication devices left, the management data is transmitted to the management device,
When each of the plurality of communication devices receives the management data, it confirms whether the management data is correct or not, and if the management data is regular data, transmits an acknowledgment to the transmission source of the management data,
When the management device receives the acknowledge, it confirms whether the acknowledge is correct, and when the management data is received , confirms whether the management data is correct, and if the acknowledge and the management data are regular data, A communication method comprising: determining that a plurality of communication devices are normally connected. A management device that manages a connection state of a plurality of communication devices, transmits management data to at least one communication device among the plurality of communication devices;
The plurality of communication devices sequentially transmit the management data to at least one other communication device that has not received the management data, and receive the management data from the communication device that has received the management data. When there are no communication devices left, the management data is transmitted to the management device,
When each of the plurality of communication devices receives the management data, the management data is confirmed to be correct or not. If the management data is regular data, an acknowledgment is added to the management data and the management data is added. Send
When the management device receives the management data, it confirms whether the management data is correct. If the management data is regular data and the acknowledge is added to the management data, the plurality of units A communication method characterized by determining that the communication device is normally connected.

Images