JP2023031447A - Key information update system, key information update method, and key information update program - Google Patents

Abstract

To provide a key information update system for updating a key in a simple configuration.SOLUTION: A wireless master unit of a key information update system is configured to update a session key to be used for encryption and decryption of a telegraphic message to be transmitted/received between the wireless master unit and a wireless slave unit, the wireless master unit including an update key information transmission unit and a master unit information transmission unit. The wireless slave unit includes an update key information receiving unit 211, a master unit information receiving unit 212, and a slave unit determination unit. The update key information transmission unit transmits update key information obtained by encrypting a to-be-updated key stored in a master unit storage unit with a session key stored in the master unit storage unit of the wireless master unit, to the wireless slave unit. The master unit information transmission unit transmits master unit information on the wireless master unit encrypted with the to-be-updated key to the wireless slave unit. The slave unit determination unit determines whether to transmit slave information on the wireless slave unit to the wireless master unit, on the basis of the update key information and the master unit information transmitted from the wireless master unit.SELECTED DRAWING: Figure 3B

Description

The present invention relates to a key information update system, a key information update method, and a key information update program.

2. Description of the Related Art Conventionally, techniques for encrypting and decrypting telegrams (messages) transmitted and received by a plurality of communication devices using keys have been proposed. In order to maintain secure communication between communication devices, it is recommended that keys used for encryption and decryption of telegrams be updated periodically. However, there are cases where the key is not updated due to non-delivery of the electronic message regarding the key update.

Patent Literature 1 discloses a key information control device that updates a key by multicast communication regarding a key used in a network including a plurality of communication devices. The key information management device disclosed in Patent Document 1 performs unicast communication with a retransmission function to update the key when the key update fails.

JP 2015-133589 A

In the key information management device disclosed in Patent Literature 1, when key update fails, it is necessary to switch to unicast communication with a retransmission function, which uses a different communication method from normal multicast communication. That is, the key information management device disclosed in Patent Document 1 needs to separately provide a communication method for when key update fails, and each communication device also needs to be compatible with a plurality of communication methods.

The present invention has been made in view of the problems of the prior art. An object of the present invention is to provide a key information update system capable of performing key update with a simple configuration.

A key information update system according to an aspect of the present invention is a key information update system that updates a session key used for encryption and decryption of messages transmitted and received between a wireless master device and a wireless slave device, The wireless master unit transmits update key information obtained by encrypting the scheduled update key stored in the master unit storage unit using the session key stored in the master unit storage unit of the wireless master unit to the wireless slave unit. Update key information transmission a parent device information transmission unit that transmits parent device information on the wireless parent device encrypted with the update schedule key to the wireless client device; and whether or not the client device information on the wireless client device transmitted from the wireless client device is received and a master device key updater that updates the session key to the update-scheduled key, and the wireless slave device receives update key information transmitted from the wireless master device, An update key information receiving unit that decrypts the update key information with the session key stored in the child device storage unit of the child device, acquires the update scheduled key, stores it in the child device storage unit, and the parent device that is transmitted from the wireless base unit. A parent device information receiving unit that receives device information and decrypts it with an update scheduled key; a child device information transmission unit that transmits child device information encrypted with an update schedule key to a wireless master device when the child device determination unit determines to transmit the child device information; and a session key that is an update schedule key. and a handset key update unit that updates the key.

A key information updating method according to another aspect of the present invention is executed by a computer, and is a key for updating a session key used for encryption and decryption of messages transmitted and received between a wireless master device and a wireless slave device. An information updating method, wherein update key information obtained by encrypting an update-scheduled key stored in a master unit storage unit with a session key stored in a master unit storage unit of the wireless master unit is transmitted to a wireless slave unit, Receiving update key information transmitted from the master device, decrypting the update key information with the session key stored in the slave device storage unit of the wireless slave device to obtain an update scheduled key, storing it in the slave device storage unit, Transmits the parent device information related to the wireless parent device encrypted with the scheduled update key to the wireless slave device, receives the parent device information sent from the wireless parent device, decrypts it with the scheduled update key, updates the update key information and the parent device information Based on, it is determined whether or not to transmit the child device information about the wireless child device to the wireless master device, and if it is determined to transmit the child device information, the child device information encrypted with the update schedule key and determines whether or not the slave device information transmitted from the wireless slave device has been received, and if it is determined that the slave device information has been received, updates the session key of the wireless master device to the update scheduled key, To update a session key of a wireless slave device to a key to be updated when the slave device information is transmitted to the wireless master device.

A key information update program according to another aspect of the present invention is for causing a computer to update a session key used for encryption and decryption of messages transmitted and received between a wireless master device and a wireless slave device. A key information update program for transmitting update key information obtained by encrypting an update-scheduled key stored in a master unit storage unit with a session key stored in a master unit storage unit of the wireless master unit to a wireless slave unit. , it receives the update key information sent from the wireless base unit, decrypts the update key information with the session key stored in the child unit storage unit of the wireless child unit, acquires the scheduled update key, and stores it in the child unit storage unit. a step of storing, a step of transmitting to the wireless slave device the master device information related to the wireless master device encrypted with the scheduled update key, and a step of receiving the master device information transmitted from the wireless master device and decrypting it with the scheduled update key. a step of determining whether or not to transmit handset information related to the wireless handset to the wireless base device based on the update key information and the base device information; a step of transmitting handset information encrypted with a key to a wireless base device; a step of determining whether handset information transmitted from a wireless handset has been received; and a step of determining that handset information has been received (2) updating the session key of the wireless master device to the scheduled update key; and updating the session key of the wireless slave device to the scheduled update key when the slave device information is transmitted to the wireless master device.

ADVANTAGE OF THE INVENTION According to this invention, the key information update system which can update a key by simple structure can be provided.

It is a figure which shows the structure of the key information update system which concerns on this embodiment. It is a figure which shows the structure of the radio|wireless machine used for the key information update system which concerns on this embodiment. It is a figure which shows the functional structure of the wireless main|base station of the key information update system which concerns on this embodiment. 3 is a diagram showing a functional configuration of a wireless slave device of the key information update system according to this embodiment; FIG. FIG. 5 is a sequence diagram for explaining an example of processing of the key information update system according to the embodiment; It is a figure which shows an example of the message|telegram transmitted/received by the key information update system which concerns on this embodiment. FIG. 4 is a sequence diagram showing an example of communication performed between a wireless master device and a wireless slave device in the key information update system according to the present embodiment; FIG. 4 is a sequence diagram showing an example of communication performed between a wireless master device and a wireless slave device in the key information update system according to the present embodiment; FIG. 4 is a sequence diagram showing an example of communication performed between a wireless master device and a wireless slave device in the key information update system according to the present embodiment;

The key information update system according to this embodiment will be described in detail below with reference to the drawings. Note that the dimensional ratios in the drawings are exaggerated for convenience of explanation, and may differ from the actual ratios. In addition, in the description of the drawings below, the same or similar parts are denoted by the same or similar reference numerals.

FIG. 1 is a diagram showing the configuration of a wireless communication system 1 to which a key information update system according to this embodiment is applied. As shown in FIG. 1, the wireless communication system 1 includes a meter reading network 10, a management device 30, and a network 40. FIG.

In this embodiment, the meter reading network 10 includes a plurality of meters 20 , and wireless devices provided in the meters 20 enable mutual communication between the meters 20 . In this embodiment, the meter 20 is, for example, a meter that measures water, gas, electricity, etc. installed in a house. Also, as a communication standard in the meter reading network 10, for example, "U Bus Air" used in a wireless telemetering system is applied. This "U-bus air" is a communication method that enables communication between wireless devices provided in the meter 20, and is a short-range wireless communication method that uses the 920 MHz band and achieves ultra-low power consumption.

The plurality of meters 20 included in the meter reading network 10 includes a master meter 20a and a plurality of slave meters 20b connected to the master meter 20a. Henceforth, when it is not necessary to distinguish between the parent device meter 20a and the child device meter 20b, they will simply be referred to as "meter 20".

The slave meter 20b includes an MT radio 200 (meter radio) as a slave radio. Note that the MT radio device 200 corresponds to a radio slave device.

In addition, master meter 20 a includes GW radio 100 that performs wireless communication with each of the plurality of MT radios 200 and further communicates with management device 30 via network 40 . Note that the GW radio device 100 corresponds to a radio master device.

The management device 30 is a communication center (centralized monitoring center) that manages information on each meter 20 included in the meter reading network 10 . For example, the management device 30 sends a meter reading data request message (message) to each meter 20 via the GW wireless device 100, and the GW wireless device 100 and the MT wireless device 200 that have received the meter reading data request message , meter reading data of the meter 20 is returned to the management device 30 . Part of the information managed by this management device 30 is provided to gas companies, water companies, and the like.

In this embodiment, the network 40 is a wide area communication network in which the management device 30 and the GW radio device 100 can communicate with each other, and is configured by, for example, a carrier network such as a mobile phone network, or the Internet. That is, the GW radio 100 has a function as a gateway that relays different wireless standards between the network 40 and the meter reading network 10 . In addition, the communication standard of the network 40 and the communication standard of the meter-reading network 10 may be the same communication standard.

(Configuration of key information update system)
Next, configurations of the GW radio device 100 and the MT radio device 200 provided in the key information update system will be described. FIG. 2 is a block diagram showing the configuration of the GW radio 100 and the MT radio 200. As shown in FIG. Since the configuration of the MT radio device 200 is the same as the configuration of the GW radio device 100, the configuration of the GW radio device 100 will be described below.

The GW radio 100 includes a control unit 110 , a storage unit 120 , an input/output IF 130 and a communication IF 140 .

The control unit 110 may be configured as, for example, a general-purpose microcomputer. In this case, a computer program for functioning as the GW radio 100 may be installed in the microcomputer. By executing the computer program, the microcomputer functions as a plurality of information processing circuits included in the GW radio 100. FIG. In addition, the control unit 110 may realize a plurality of information processing circuits provided in the GW radio 100 by software, or may prepare dedicated hardware to configure the information processing circuits. Also, a plurality of information processing circuits may be configured by individual hardware.

The storage unit 120 stores master key information 121 and/or session key information 122, which will be described later, as data. Note that the number of storage units 120 that store each of these data may be one or plural. For example, one storage unit 120 may be configured to be stored in divided areas. Alternatively, data may be distributed and stored in a plurality of storage devices installed at physically separate locations. Note that the storage unit 120 of the GW radio device 100 corresponds to the parent device storage unit, and the storage unit 220 of the MT radio device 200 corresponds to the child device storage unit.

The input/output IF 130 is, for example, a component (interface) for the user to exchange data with the GW radio device 100 . A user can set the meter 20 or the GW radio 100 via the input/output IF 130 . In addition, the input/output IF 130 provides information on the meter 20 or the GW radio 100 via a display unit (not shown) provided in the meter 20 or the GW radio 100 or connected to the meter 20 or the GW radio 100. can be displayed. Via the input/output IF 130, the user can obtain the information of the meter 20 or the GW radio 100 displayed on the display unit.

Communication IF 140 of GW radio 100 is an interface for enabling communication between GW radio 100 and MT radio 200 via communication IF 240 of MT radio 200 . Also, the communication IF 140 of the GW radio 100 has a function to enable communication with the management device 30 via the network 40 .

(Function of key information update system)
Next, functions of the key information update system will be described. FIG. 3A is a functional block diagram showing functions of the GW radio 100. As shown in FIG. FIG. 3B is a functional block diagram showing functions of the MT radio 200. As shown in FIG. The functions of the key information update system shown in FIGS. 3A and 3B will be described below using the sequence diagram shown in FIG.

As shown in FIG. 3A, the control unit 110 of the GW radio device 100 includes an update key information transmission unit 111, a parent device information transmission unit 112, a determination unit 113, and a session key update unit 115 as functions. Also, the storage unit 120 of the GW radio device 100 stores master key information 121 and session key information 122 . Note that the determination unit 113 of the GW radio device 100 corresponds to the master device determination unit. Also, the session key updating unit 115 of the GW radio device 100 corresponds to the parent device key updating unit.

In this embodiment, the master key is key information used when generating, duplicating, or processing a key, and is used, for example, when generating a session key. Also, in the present embodiment, the session key is key information used for encrypting and decrypting messages sent and received in communication between the GW radio device 100 and the MT radio device 200 .

Further, as shown in FIG. 3B, the control unit 210 of the MT radio device 200 includes an update key information receiving unit 211, a parent device information receiving unit 212, a determining unit 213, a child device information transmitting unit 214, a session key and an updating unit 215 as functions. Note that the determining section 213 of the MT radio device 200 corresponds to the child device determining section. Also, the session key updating unit 215 of the MT radio device 200 corresponds to the slave device key updating unit.

Also, the storage unit 220 of the MT radio device 200 stores session key information 222 . Although the example shown in FIG. 3B shows an example in which the storage unit 220 does not include an area related to master key information, this configuration does not limit the configuration of the present embodiment. The storage unit 220 may be configured to include an area related to master key information.

The session key information 122 and the session key information 222 shown in FIG. 4 are provided with two areas, a C area (Current area) and an N area (Next area). key is stored. The C area stores a session key used for messages transmitted and received between the current GW radio 100 and MT radio 200 . The N area stores an update-scheduled key to be updated in the next update of the session key. Note that, in the present embodiment, the session key, which is the scheduled update key stored in the N area, is also used for part of the telegrams transmitted and received between the current GW radio device 100 and the MT radio device 200. be done. The details of application of the session key stored in this N area will be described later.

FIG. 4 shows an example in which session key S1 is stored in area C of session key information 122 as the currently used session key at the start of the process shown in FIG. In the example shown in FIG. 4, the session key S2 is stored in the N area of the session key information 122 as an update-scheduled key to be updated in the next key update process.

Similarly, at the start of the process shown in FIG. 4, the session key S1 is stored in the C area of the session key information 222 as the currently used session key. On the other hand, at the start of the process shown in FIG. 4, an example is shown in which the update-scheduled key to be updated in the next update process is not stored in the N area of the session key information 222 .

FIG. 5 shows an example of messages transmitted and received between the GW radio 100 and the MT radio 200 shown in FIG. In this embodiment, the electronic message regarding key setting or key update includes "update key information" transmission, "parent device information" transmission, and "child device information" transmission. Telegrams relating to data transmission/reception performed between the GW radio device 100 and the MT radio device 200 include, for example, telegrams of "meter reading data request" and "meter reading data response". Note that the "session key (C area)" and "update key (N area)" described in the column of "encryption/decryption key information" in FIG. , and information about the key used to decrypt the message. In this embodiment, the information about the key corresponding to this message is stored in the header of each message, and the wireless device on the receiving side of the message reads the message based on the information about the key stored in this header. to decrypt.

The update key information transmission unit 111 of the GW radio device 100 transmits “update key information” to be updated to the MT radio device 200 . Specifically, the update key information transmission unit 111 uses the session key stored in the C area of the session key information 122 of the storage unit 120 of the GW radio device 100 to update the update schedule stored in the N area of the session key information 122 . The updated key information obtained by encrypting the key is transmitted to the MT radio device 200 . The processing in which the update key information transmitting unit 111 transmits the "update key information" corresponds to step S401 in the example of FIG.

Specifically, in step S401, the GW radio device 100, which is the parent device, transmits a telegram (message) of "update key information" to the MT radio device 200, which is the child device. Here, it is assumed that the "update key information" includes information about the session key S2. "Update key information" is information encrypted with the session key S1 and is a message that can be decrypted with the session key S1.

In addition, in FIG. 4, the keys for encryption and decryption of messages transmitted and received between the GW radio device 100 and the MT radio device 200 are shown in parentheses. That is, in the example shown in FIG. 4, each message is a message encrypted by the session key S1 or session key S2 corresponding to the parenthesized key (S1 or S2) and is a decryptable message. .

The update key information receiving section 211 of the MT radio device 200 receives the “update key information” transmitted from the GW radio device 100 . Specifically, the update key information receiving unit 211 receives the “update key information” transmitted from the GW radio device 100, and receives the “update key information” using the session key stored in the C area of the session key information 222. Decrypt and get the scheduled update key. Furthermore, the update key information receiving unit 211 stores the decrypted update-scheduled key in the N area of the session key information 222 of the storage unit 220 . The process for the update key information receiving unit 211 to receive the "update key information" corresponds to step S402 in the example shown in FIG.

Specifically, in step S402, the update key information receiving unit 211 of the MT radio device 200 receives the “update key information” transmitted from the GW radio device 100, and saves it to the session key information 222 of the storage unit 220. Store. In the example shown in FIG. 4, the MT radio device 200 transmits the "update key information" including the information about the session key S2 with the session key S1 based on the information set in the header of the "update key information" message. It is decrypted and stored in the N area of the session key information 222 . In the example shown in FIG. 4, the N area of the session key information 222 stores the session key S2, which is the scheduled update key.

Next, the master device information transmission unit 112 transmits a message of “master device information” from the GW radio device 100 to the MT radio device 200 . Specifically, the master device information transmitting unit 112 transmits the “master device information” regarding the GW radio device 100 encrypted with the “update planned key” stored in the N area of the session key information 122 to the MT radio device 200. do. The process of transmitting the "parent device information" by the parent device information transmitting unit 112 corresponds to step S403.

Specifically, in step S<b>403 , the master device information transmission unit 112 of the GW radio device 100 transmits “master device information” to the MT radio device 200 . In the example shown in FIG. 4, the "parent device information" transmitted in step S403 is encrypted with the session key S2, which is the scheduled update key. Also, the “master device information” transmitted in step S403 is information about the GW radio device 100 that is the master device, for example, information for identifying the GW radio device 100 .

Also, in step S403, the master device information receiving unit 212 of the MT radio device 200 receives the “master device information” transmitted from the GW radio device 100. FIG. Specifically, the parent device information receiving unit 212 receives the “parent device information” transmitted from the GW radio device 100, and decrypts it with the “update scheduled key” stored in the N area of the session key information 222. . As shown in FIG. 5, the key for decrypting the "parent device information" is the session key S2 of the scheduled update key stored in the N area. In the example shown in FIG. 4, at the timing when the "coordinator information" transmitted from the GW radio device 100 in step S403 is received by the coordinator information receiving unit 212, the session key S2 is stored in the N area of the session key information 222. is stored. Therefore, in step S403, the master device information receiving unit 212 of the MT radio device 200 decrypts the “master device information” using the session key S2 of the N region, and the “master device information” that is information about the GW radio device 100 ” is obtained.

The determination unit 113 of the GW radio device 100 determines whether or not the "child device information" transmitted from the MT radio device 200 has been received in step S404 described later. Further, in steps S401 and S403, the determination unit 213 of the MT radio device 200 sends the GW radio device 100 a It is determined whether or not to transmit "slave device information". In the present embodiment, the determination unit 213 of the MT radio device 200, when receiving the “update key information” and the “parent device information”, or when receiving the “update key information” at least twice, determines whether the “child device information” to the GW radio device 100. Details of the processing of the determination unit 113 and the determination unit 213 will be described in processing example 1 to processing example 3 of the key information update system described later.

The child device information transmission section 214 of the MT radio device 200 transmits “child device information” to the GW radio device 100 based on the determination result of the determination section 213 . Specifically, when the determination unit 213 determines that the “child device information” is to be transmitted, the child device information transmission unit 214 encrypts the data with the “update scheduled key” stored in the N area of the session key information 222 . GW radio device 100 is transmitted to the GW radio device 100. The processing in which the child device information transmission unit 214 transmits the "child device information" to the GW radio device 100 corresponds to step S404 in the sequence diagram of FIG.

Specifically, in step S404, the slave device information transmission unit 214 of the MT radio device 200 encrypts and transmits the “child device information” to the GW radio device 100. FIG. In the example shown in FIG. 4, the "slave device information" transmitted in step S404 is encrypted with the session key S2, which is the scheduled update key. Further, the “child device information” transmitted in step S404 is information related to the MT radio device 200, which is a child device, and is information for identifying the MT radio device 200, for example.

Also, in step S404, the slave device information receiving unit 114 of the GW radio device 100 receives the “child device information” transmitted from the MT radio device 200. FIG. The slave device information receiving unit 114 of the GW radio device 100 uses the session key S2, which is the update schedule key in the N area of the session key information 122, to decrypt the "child device information" encrypted with the update schedule key, The “slave device information”, which is information related to the MT radio device 200, is acquired.

The session key update unit 115 of the GW radio device 100 updates the session key of the C area of the session key information 122 to the session key of the N area. Specifically, when determining unit 113 determines that the “child device information” has been received, session key updating unit 115 updates the session key in area C of session key information 122 to the “update Update to scheduled key. The process for updating the key of this session key updating unit 115 corresponds to step S405.

Specifically, in step S405, the session key update unit 115 of the GW radio device 100 updates the session key. In the example shown in FIG. 4, the session key stored in area C of the session key information 122 is updated from session key S1 to session key S2.

Also, the session key update unit 215 of the MT radio device 200 updates the session key information 222 . Specifically, when the “child device information” is transmitted to the GW radio device 100 by the child device information transmission section 214, the session key updating section 215 updates the session key of the C region of the session key information 222 to the N region. update to the scheduled update key. The process for updating the key of this session key updating unit 215 corresponds to step S406.

Specifically, in step S406, the session key update unit 215 of the MT radio device 200 updates the session key. In the example shown in FIG. 4, the session key stored in area C of the session key information 222 is updated from session key S1 to session key S2. The process of updating the session key of the MT radio device 200 in step S406 is performed based on the process of transmitting the "slave device information" in step S404.

In step S<b>407 , the GW radio device 100 transmits a “meter reading data request” message to the MT radio device 200 . This "meter reading data request" message is encrypted with the session key S2. In addition, in step S407, the MT radio device 200 receives a telegram of "meter reading data request". Information to the effect that the key stored in the C area is used for decryption is stored in the header of the electronic message "request for meter reading data". Based on the header information, the MT radio device 200 decrypts the "meter reading data request" with the session key S2 stored in the C area in step S406. As described above, in step S406, the session key updating unit 215 decrypts the message regarding the "meter reading data request" without any problem because the key in the C area of the session key information 222 has been updated from the session key S1 to the session key S2. can be In the example shown in FIG. 4, the description of normal message transmission/reception between the GW radio device 100 and the MT radio device 200 after the "meter reading data request" is omitted.

Next, FIG. 6 to FIG. 8 will be used to describe the processing in the case where any of the telegrams sent and received between the GW radio device 100 and the MT radio device 200 fails to arrive. In the examples of FIGS. 6 to 8 below, explanations of the same processes as those shown in the sequence diagram of FIG. 4 will be omitted or simplified. In the present embodiment, non-delivery of a telegram means a situation in which a telegram transmitted from the transmitting side of the wireless device cannot be received by the receiving side for some reason. Further, non-delivery is caused by various factors such as fixed failure, temporary intermittent failure, or one-off failure in the wireless device or communication path.

(Processing example 1 of the key information update system)
FIG. 6 shows an example of processing in the case where the “update key information” telegram transmitted from the GW radio device 100 to the MT radio device 200 fails to arrive.

In step S601, the message of "update key information" transmitted from the GW radio device 100 to the MT radio device 200 has not arrived, and the "update key information" is received by the update key information receiving section 211 of the MT radio device 200. Indicates when reception is not possible. In this case, in the MT radio device 200, the information of the session key S2 is not stored in the N area of the session key information 222. FIG.

In step S<b>602 , “master device information” is transmitted from the GW radio device 100 to the MT radio device 200 . Here, since the session key S2 is not stored in the N area of the session key information 222, the parent device information receiving section 212 of the MT radio device 200 cannot decrypt the “parent device information”. Therefore, the determination unit 213 of the MT radio device 200 transmits the “child device information” to the GW radio device 100 based on the transmission status of the “update key information” and the “parent device information” transmitted from the GW radio device 100. Decide not to.

In step S603, the determination unit 113 of the GW radio device 100 determines whether or not the "child device information" transmitted from the MT radio device 200 has been received. In the example shown in FIG. 6, as described above, the "update key information" has not arrived, and the determination unit 213 of the MT radio device 200 has determined that the "child device information" will not be transmitted. Therefore, at the timing of step S603 in FIG. 6, the "child device information" is not transmitted from the MT radio device 200, and the GW radio device 100 does not receive the "child device information". In step S603, if the GW radio device 100 does not receive the "child device information" for a predetermined period of time, the update key information transmitting unit 111 of the GW radio device 100 sends the "update key information" to the MT radio device 200. Retransmit (step S604). Also, the parent device information transmitting unit 112 retransmits the “parent device information” (step S606).

Here, in the example shown in FIG. 6, when the "update key information" from the GW radio device 100 to the MT radio device 200 remains undelivered, the processing from step S603 to step S606 is repeated. A loop L6 is performed. This loop L6 is assumed to be a predetermined number of times, for example, 10 loops. Note that the number of loops is not limited to the configuration of the present embodiment, and the number of loops may be less than 10 times or more than 10 times.

For example, if some kind of fixed failure occurs in the MT radio device 200 and the message of "update key information" continues to be undelivered, after the loop L6 is executed a predetermined number of times, the following is shown in FIG. Processing of the indicated sequence ends. Then, the GW radio device 100 performs the processing from step S601 on another MT radio device 200 included in the meter reading network 10 and subject to key update.

On the other hand, if the “update key information” message is transmitted to the MT radio device 200 in less than the predetermined number of loops of 10 due to a single (intermittent) communication failure or the like, steps S605 to S609 are performed. , and the session key is updated. Note that the processing from step S607 to step S610 is the same as the processing from step S404 to step S407 shown in FIG. 4, so description thereof will be omitted. In addition, in the example shown in FIG. 6, the description of normal message transmission/reception between the GW radio device 100 and the MT radio device 200 after the "meter reading data request" is omitted.

In this way, in the key information update system, even if the message of "update key information" is not delivered, if the non-delivery occurs only once (intermittently), the "update key Information" is sent, the key information is updated without any problem.

(Processing example 2 of the key information update system)
FIG. 7 shows an example of processing in the case where the “master device information” telegram transmitted from the GW radio device 100 to the MT radio device 200 fails to arrive.

In step S701 shown in FIG. 7, unlike step S601 shown in FIG. Therefore, the update key information receiving section 211 of the MT radio device 200 receives the “update key information” from the GW radio device 100 and stores the scheduled update key in the N area of the session key information 222 .

In the example shown in FIG. 7, an example is shown in which the telegram for "parent device information" in step S703 has not arrived. Since the telegram of "parent device information" in step S703 has not arrived, the determination unit 213 of the MT radio device 200 transmits "child device information" based on the situation in which the telegram of "parent device information" has not arrived. Decide not to. Therefore, in response to non-delivery in step S703, the telegram of "slave device information" is not transmitted from the MT radio device 200. FIG.

In step S704, the determination unit 113 of the GW radio device 100 determines whether or not the telegram of "child device information" has been transmitted from the MT radio device 200. FIG. In the example shown in FIG. 7, the "child device information" from the MT radio device 200 is not transmitted at the timing of step S704. Therefore, the update key information transmission unit 111 and the master device information transmission unit 112 of the GW radio device 100 transmit the "update key information" and the "master device information" to the MT radio device 200 (steps S705 and S706).

Here, in the example shown in FIG. 7, it is again assumed that the "parent device information" message in step S706 has not arrived. The determination unit 213 of the MT radio device 200 receives the second “update key information” in a state where the first “update key information” is received, and triggers the reception of the second “update key information” to transmit the “slave device information” to the GW radio device 100 . determined to transmit to That is, the determination unit 213 of the MT radio device 200 determines to transmit the “child device information” to the GW radio device 100 when the “update key information” is received at least twice. Since the session key S2 is stored in the N area of the session key information 222 in step S702, there is no problem in communication with the GW radio device 100 even if the key information in the C area is updated to the session key S2. That is, in the example shown in FIG. 7, even if the "master device information" from the GW radio device 100 remains undelivered, the session key update process is performed without any problem.

The processing from step S708 to step S711 is the same as that from step S404 to step S407 of the sequence shown in FIG. 4, so description thereof will be omitted. In addition, in the example shown in FIG. 7, the description of normal message transmission/reception between the GW radio device 100 and the MT radio device 200 after the "meter reading data request" is omitted.

The example shown in FIG. 7 shows an example in which the telegram of "parent device information" in step S706 remains undelivered. Here, for example, even if the telegram of "update key information" in step S705 does not arrive and the telegram of "parent device information" in step S706 is sent, the session key is updated without any problem. That is, in the example shown in FIG. 7, the MT radio device 200 is in a state in which the message of "update key information" in step S701 has been transmitted. Therefore, in the MT radio device 200, if the electronic message for "update key information" in step S705 has not arrived and the electronic message for "parent device information" in step S706 has been transmitted, the "parent device information" in step S706 Upon reception, processing equivalent to that of a normal protocol is performed.

As described above, in the key information update system of the present embodiment, even if the telegram of the "parent device information" is not delivered, the occurrence of the non-delivery of the telegram of the "parent device information" is permanent, or It is possible to update the session key information regardless of whether it is sporadic (intermittent).

(Processing example 3 of the key information update system)
FIG. 8 shows an example of processing in the case where the telegram of "child device information" transmitted from the MT radio device 200 to the GW radio device 100 fails to arrive.

Since the processing from step S801 to step S803 is the same as the processing from step S401 to step S403 shown in FIG. 4, the description is omitted here.

In the example shown in FIG. 8, in step S804, an example is shown in which the electronic message of "slave device information" from the MT radio device 200 has not arrived.

In step S805, the determination unit 113 of the GW radio device 100 determines whether or not the "child device information" transmitted from the MT radio device 200 has been received. At the timing of step S805 in FIG. 8, the “child device information” from the MT radio device 200 is not transmitted. In step S805, if the GW radio device 100 does not receive the "child device information" for a predetermined period of time, the update key information transmitting unit 111 of the GW radio device 100 sends the "update key information" to the MT radio device 200. Retransmit (step S806). Also, the parent device information transmitting unit 112 resends the “parent device information” (step S807).

Here, in the example shown in FIG. 8, when the "slave device information" from the MT radio device 200 to the GW radio device 100 remains undelivered, the processing from step S804 to step S807 is repeated. A loop L8 is executed. This loop L8 is assumed to be a predetermined number of times, for example, 10 loops. Note that the number of loops is not limited to the configuration of the present embodiment, and the number of loops may be less than 10 times or more than 10 times.

For example, if some kind of fixed failure occurs in the MT radio device 200 and the telegram of "slave device information" continues to be undelivered, after the loop L8 is executed a predetermined number of times, the following is shown in FIG. Processing of the indicated sequence ends. Then, the GW radio device 100 performs the processing from step S801 on the other MT radio device 200 included in the meter reading network 10 and subject to key update.

On the other hand, if the telegram of "child device information" is transmitted to the GW radio device 100 in a loop count less than the predetermined 10 times due to a single (intermittent) communication failure or the like, steps S808 to S810 are performed. , and the session key is updated. Note that the processing from step S808 to step S811 is the same as the processing from step S404 to step S407 shown in FIG. 4, so description thereof will be omitted. In addition, in the example shown in FIG. 8, the description of normal message transmission/reception between the GW radio device 100 and the MT radio device 200 after the "meter reading data request" is omitted.

As described above, in the key information update system of this embodiment, even if the telegram of "child device information" is undeliverable, if the undeliverable occurrence is sporadic (intermittent), The key information is updated without any problem by transmitting the "slave device information" message again.

As described above, the key information update system in this embodiment is a key information update system that updates session keys used for encryption and decryption of telegrams sent and received between a wireless master device and a wireless slave device. . The wireless master device of the key information update system includes an update key information transmitter 111 and a master device information transmitter 112 . The wireless slave device also includes an update key information receiving section 211, a parent device information receiving section 212, and a child device determination section. The update key information transmission unit 111 transmits update key information obtained by encrypting the scheduled update key stored in the parent device storage unit using the session key stored in the parent device storage unit of the wireless master device, to the wireless slave device. In addition, the parent device information transmitting unit 112 transmits parent device information related to the wireless parent device encrypted with the update-scheduled key to the wireless slave device. The slave device determination unit determines whether or not to transmit slave device information related to the wireless slave device to the wireless master device based on the update key information and the master device information transmitted from the wireless master device.

This makes it possible to realize a key information update system that can update keys with a simple configuration without the need to provide a separate communication method for key update even when a telegram about key update does not arrive. . Note that the wireless master device corresponds to the GW wireless device 100 . A radio slave device corresponds to the MT radio device 200 . Also, the slave device determination unit corresponds to the determination unit 213 .

Further, the slave unit determination unit of the key information update system transmits the slave unit information to the wireless master unit when the update key information and the master unit information are received, or when the update key information is received at least twice. You can judge. As a result, in the key information update system, even if the telegram of the "parent device information" is undelivered, the occurrence of the non-delivery of the telegram of the "parent device information" is permanent or sporadic (intermittent). ), the session key information can be updated.

Further, the update key information transmitting unit 111 of the key information updating system may transmit the update key information to the wireless slave unit again when the master unit determining unit determines that the slave unit information has not been received. . As a result, in the key information update system, even if the "child device information" telegram fails to arrive, if the non-delivery occurs only once (intermittently), the "child device information ” is sent, the key information is updated without any problem.

(Other embodiments)
Although the embodiment has been described in detail with reference to the drawings, the present embodiment is not limited by the contents described in the above embodiment. In addition, the components described above include components that can be easily assumed by those skilled in the art and components that are substantially the same. Furthermore, the configurations described above can be combined as appropriate. In addition, various omissions, substitutions, or changes in configuration can be made without departing from the gist of the embodiments.

As an example of the configuration of the key information update system according to the present embodiment, an example in which telegrams are transmitted and received between one GW radio 100 and a plurality of MT radios 200 as shown in FIG. Configurations are not intended to limit embodiments. For example, the child meter 20b may be connected to another child meter 20b via the MT radio 200. FIG. That is, in the key information update system, the MT radio 200 relays telegrams (messages) sent and received between the GW radio 100 of the master meter 20a and the MT radio 200 of the other slave meter 20b. It may be configured by multi-hop capable of By realizing the key information update system in a multi-hop configuration, it is possible to efficiently expand the communication area of the meter reading network 10 and to eliminate blind areas caused by obstacles.

In addition, a computer program (key information update program) that causes a computer to execute the processing (key information update method) in the key information update system described above, and a computer-readable recording medium that records the program are within the scope of the present embodiment. include. Here, any type of computer-readable recording medium may be used. The computer program is not limited to being recorded on the recording medium, and may be transmitted via an electric communication line, a wireless or wired communication line, a network represented by the Internet, or the like.

Features of the key information update system, the key information update method, and the key information update program are described below.

A key information update system according to a first aspect is a key information update system that updates a session key used for encryption and decryption of messages transmitted and received between a wireless master device and a wireless slave device. The wireless master unit transmits update key information obtained by encrypting the scheduled update key stored in the master unit storage unit using the session key stored in the master unit storage unit of the wireless master unit to the wireless slave unit. Update key information transmission A unit 111 is provided. The wireless master device also includes a master device information transmission unit 112 that transmits to the wireless slave device master device information regarding the wireless master device encrypted with the update-scheduled key. Further, the wireless master device includes a master device determination unit that determines whether or not the slave device information regarding the wireless slave device transmitted from the wireless slave device has been received. The wireless master device also includes a master device key updating unit that updates the session key to the update-scheduled key when the master device determination unit determines that the slave device information has been received. The wireless slave device receives the update key information transmitted from the wireless master device, decrypts the update key information with the session key stored in the slave device storage unit of the wireless slave device, acquires the scheduled update key, and It has an update key information receiving unit 211 that stores in the storage unit. The wireless slave device also includes a master device information receiving unit 212 that receives the master device information transmitted from the wireless master device and decrypts it with the update-scheduled key. The wireless slave device also includes a slave device determination unit that determines whether or not to transmit slave device information to the wireless master device based on the update key information and the master device information. The wireless slave device also includes a slave device information transmission unit 214 that transmits the slave device information encrypted with the update-scheduled key to the wireless master device when the slave device determination unit determines to transmit the slave device information. Further, the wireless slave device includes a slave device key updating unit that updates the session key to the scheduled update key when the slave device information transmission unit 214 transmits the slave device information to the wireless master device.

According to the above configuration, the key information update system does not require a separate communication method for key update even if the key update message does not arrive, and the key update can be performed with a simple configuration. It becomes possible.

The child device determination unit of the key information updating system according to the second aspect receives the child device information when receiving the update key information and the parent device information, or when receiving the update key information at least twice. It may be determined to transmit to the machine.

According to the above configuration, in the key information update system, even when the telegram of the "parent device information" is undelivered, the occurrence of the non-delivery of the telegram of the "parent device information" is permanent or sporadic ( It is possible to update the session key information regardless of whether it is intermittent or not.

The update key information transmitting unit 111 of the key information updating system according to the third aspect transmits the update key information to the wireless slave unit again when the master unit determining unit determines that the slave unit information has not been received. You may

According to the above configuration, even if the telegram of "child device information" is undelivered, if the non-delivery occurs only occasionally (intermittently), the key information update system Key information is updated without any problem by transmitting the telegram of “machine information”.

The wireless slave device of the key information update system according to the fourth aspect may be capable of relaying messages sent and received between the wireless master device and other wireless slave devices.

According to the above configuration, the key information update system can efficiently expand the communication area of the meter reading network 10 and eliminate dead areas caused by obstacles.

A key information update method according to a fifth aspect is executed by a computer, and performs key information update for updating a session key used for encryption and decryption of messages transmitted and received between a wireless master device and a wireless slave device. The method. The key information update method is to transmit update key information obtained by encrypting the update-scheduled key stored in the master device storage unit with the session key stored in the master device storage unit of the wireless master device to the wireless slave device. Also, the key information updating method receives the update key information transmitted from the wireless base unit, decrypts the update key information with the session key stored in the slave unit storage unit of the wireless slave unit, and acquires the scheduled update key. , is stored in the slave unit storage unit. Further, the key information updating method transmits to the wireless slave device the master device information regarding the wireless master device encrypted with the update-scheduled key. Also, the key information update method receives the parent device information transmitted from the wireless parent device and decrypts it with the update-scheduled key. Further, the key information updating method determines whether or not to transmit handset information regarding the wireless handset to the wireless base device based on the update key information and the base device information. Further, in the key information updating method, when it is determined that the child device information is to be transmitted, the child device information encrypted with the update-scheduled key is transmitted to the wireless master device. Also, the key information update method determines whether or not the slave device information transmitted from the wireless slave device has been received. Further, the key information update method updates the session key of the wireless master device to the update-scheduled key when it is determined that the slave device information has been received. Furthermore, the key information updating method updates the session key of the wireless slave device to the update-scheduled key when the slave device information is transmitted to the wireless master device.

According to the above configuration, the key information update method makes it possible to perform key update with a simple configuration without the need to provide a separate communication method for key update even when a telegram regarding key update does not arrive. It becomes possible.

A key information update program according to a sixth aspect is key information for causing a computer to update a session key used for encryption and decryption of messages transmitted and received between a wireless master device and a wireless slave device. It's an update. The key information update program comprises a step of transmitting update key information obtained by encrypting an update-scheduled key stored in the master unit storage unit with a session key stored in the master unit storage unit of the wireless master unit to the wireless slave unit. . In addition, the key information update program receives the update key information transmitted from the wireless master device, decrypts the update key information with the session key stored in the slave device storage unit of the wireless slave device, and acquires the scheduled update key. , and a step of storing in the slave unit storage unit. The key information update program also includes a step of transmitting to the wireless slave device the master device information regarding the wireless master device encrypted with the update-scheduled key. The key information update program also includes a step of receiving parent device information transmitted from the wireless parent device and decrypting it with the update-scheduled key. Further, the key information update program has a step of determining whether or not to transmit handset information regarding the wireless handset to the wireless master device based on the update key information and the master device information. Further, the key information update program includes a step of transmitting the child device information encrypted with the update-scheduled key to the wireless master device when it is determined that the child device information is to be transmitted. The key information update program also includes a step of determining whether or not the slave device information transmitted from the wireless slave device has been received. Further, the key information update program has a step of updating the session key of the wireless master device to the update-scheduled key when it is determined that the slave device information has been received. Further, the key information update program includes a step of updating the session key of the wireless slave device to the update-scheduled key when the slave device information is transmitted to the wireless master device.

According to the above configuration, the key information update program can perform key update with a simple configuration without the need to provide a separate communication method for key update even when a telegram regarding key update does not arrive. It becomes possible.

1 wireless communication system 10 meter reading network 20 meter 30 management device 40 network 100 GW wireless device 110, 210 control unit 200 MT wireless device 111 update key information transmission unit 112 master device information transmission unit 113, 213 determination unit 114 slave device information reception unit 115, 215 session key update unit 120, 220 storage unit 211 update key information reception unit 212 parent device information reception unit 214 child device information transmission unit

Claims (6)

A key information update system for updating a session key used for encryption and decryption of messages sent and received between a wireless master device and a wireless slave device,
The wireless base unit
An update key information transmission unit that transmits update key information obtained by encrypting an update scheduled key stored in the parent device storage unit with the session key stored in the parent device storage unit of the wireless master device to the wireless slave device. and,
a base device information transmitting unit that transmits base device information related to the wireless base device encrypted with the update schedule key to the wireless slave device;
a parent device determination unit that determines whether or not handset information related to the wireless handset transmitted from the wireless handset is received;
a parent device key updating unit that updates the session key to the update-scheduled key when the parent device determination unit determines that the child device information has been received;
The wireless slave device
receiving the update key information transmitted from the wireless master device, decrypting the update key information with the session key stored in the slave device storage unit of the wireless slave device to obtain the update scheduled key; an update key information receiving unit stored in the child device storage unit;
a base device information receiving unit that receives the base device information transmitted from the wireless base device and decrypts it with the update-scheduled key;
a slave device determination unit that determines whether or not to transmit the slave device information to the wireless master device based on the update key information and the master device information;
a child device information transmission unit configured to transmit the child device information encrypted with the update-scheduled key to the wireless master device when the child device determination unit determines to transmit the child device information;
a handset key updating unit for updating the session key to the update-scheduled key when the handset information is transmitted to the wireless master device, in the handset information transmission unit;
Key information update system. The slave device determination unit determines to transmit the slave device information to the wireless master device when the update key information and the master device information are received, or when the update key information is received at least twice. do,
The key information update system according to claim 1. The update key information transmission unit retransmits the update key information to the wireless slave device when the parent device determination unit determines that the child device information has not been received.
The key information update system according to claim 1 or 2. 4. The key information update system according to any one of claims 1 to 3, wherein said wireless slave device is capable of relaying messages transmitted and received between said wireless master device and said other wireless slave device. A key information updating method executed by a computer for updating a session key used for encrypting and decrypting messages transmitted and received between a wireless master device and a wireless slave device,
transmitting update key information obtained by encrypting an update-scheduled key stored in the base unit storage unit with the session key stored in the base unit storage unit of the wireless base unit to the wireless slave unit;
receiving the update key information transmitted from the wireless master device, decrypting the update key information with the session key stored in the slave device storage unit of the wireless slave device to obtain the update scheduled key; stored in the handset memory,
transmitting base device information related to the wireless base device encrypted with the scheduled update key to the wireless base device;
receiving the base device information transmitted from the wireless base device, decrypting it with the update schedule key;
determining whether or not to transmit handset information related to the wireless handset to the wireless base device based on the update key information and the base device information;
when determining to transmit the child device information, transmitting the child device information encrypted with the update-scheduled key to the wireless master device;
determining whether or not the slave device information transmitted from the wireless slave device has been received;
updating the session key of the wireless master device to the update-scheduled key when determining that the slave device information has been received;
A key information updating method, wherein the session key of the wireless slave device is updated to the update-scheduled key when the slave device information is transmitted to the wireless master device. A key information update program for causing a computer to update a session key used for encryption and decryption of messages sent and received between a wireless master device and a wireless slave device,
a step of transmitting update key information obtained by encrypting an update-scheduled key stored in the base unit storage unit with the session key stored in the base unit storage unit of the wireless base unit to the wireless slave unit;
receiving the update key information transmitted from the wireless master device, decrypting the update key information with the session key stored in the slave device storage unit of the wireless slave device to obtain the update scheduled key; a step of storing in the child device storage unit;
a step of transmitting to the wireless slave device the master device information regarding the wireless master device encrypted with the update-scheduled key;
a step of receiving the base device information transmitted from the wireless base device and decrypting it with the update-scheduled key;
a step of determining whether or not to transmit handset information relating to the wireless handset to the wireless base device based on the update key information and the base device information;
a step of transmitting the child device information encrypted with the update-scheduled key to the wireless master device when it is determined that the child device information is to be transmitted;
determining whether or not the slave device information transmitted from the wireless slave device has been received;
updating the session key of the wireless master device to the update-scheduled key when it is determined that the slave device information has been received;
updating the session key of the wireless slave device to the update-scheduled key when the slave device information is transmitted to the wireless master device;
A key information updater comprising:

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