JP2015216413A - Terminal, server, encryption communication system, and encryption communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a terminal capable of reducing the risk of wiretapping by a third person.SOLUTION: A terminal 1 transmits data to a server. The terminal 1 stores a key which is used for data encryption and decryption and shared with the server. The terminal 1, when a predetermined condition is satisfied, updates the key using the data which the terminal 1 has transmitted to the server.

Description

  The present invention relates to a terminal, a server, an encryption communication system, an encryption communication method, a terminal program, and a server program that perform communication by encrypting data.

  An example of a data encryption method is described in Patent Document 1. In the method described in Patent Literature 1, an encryption key is generated using identification information unique to hardware installed in a user terminal.

JP 2007-150780 A

  When a device that performs communication uses a key used for data encryption and decryption for a long period of time, there is a high possibility that the key will be leaked. Then, there is a high possibility that the communication data is wiretapped by a third party.

  Therefore, an object of the present invention is to provide a terminal, a server, an encryption communication system, an encryption communication method, a terminal program, and a server program that can suppress the risk of eavesdropping by a third party.

  A terminal according to the present invention is a terminal that transmits data to a server and is a key used for data encryption and decryption, stores a key common to the server, and when a predetermined condition is satisfied, The key is updated using data transmitted from the terminal to the server.

  The server according to the present invention is a server that receives data from a terminal and is a key used for data encryption and decryption, stores a common key with the terminal, and when a predetermined condition is satisfied, The key is updated using data transmitted from the terminal to the server.

  The cryptographic communication system according to the present invention includes a terminal that transmits data and a server that receives data. The terminal and the server each store a common key used for data encryption and decryption, and a predetermined key. When the condition is satisfied, the key is updated using data transmitted from the terminal to the server.

  Also, the encryption communication method according to the present invention is such that a terminal that transmits data and a server that receives data each store a common key used for data encryption and decryption, and a predetermined condition is satisfied. Further, the key is updated using data transmitted from the terminal to the server.

  A terminal program according to the present invention is a key used for data encryption and decryption, and includes a key storage means for storing a key common to the server, and is a terminal mounted on a computer that transmits data to the server. Program for encrypting data in a computer using a key and transmitting the encrypted data to a server, and stored in a key storage means when a predetermined condition is satisfied A key update process is performed in which the key is updated using data that has been transmitted to the server most recently and is not yet encrypted.

  The server program according to the present invention is a key used for data encryption and decryption, and includes a key storage means for storing a key common to the terminal, and is installed in a computer that receives data from the terminal. In the computer, the decryption process for decrypting the data received from the terminal using the key, and the key stored in the key storage means when the predetermined condition is satisfied, A key update process for updating the received data using the decrypted data is executed.

  According to the present invention, eavesdropping by a third party can be prevented.

It is a block diagram which shows the example of the encryption communication system of this invention. It is a block diagram which shows the structural example of a smart meter. It is a block diagram which shows the structural example of a server. It is a sequence diagram which shows the example of the process progress at the time of key update. It is a sequence diagram which shows the example of a process progress when a smart meter transmits meter-reading data to a server. It is a sequence diagram which shows the example of process progress when a server transmits data to a smart meter. It is a schematic diagram which shows the state in which the smart meter was connected to the traceability system. It is a sequence diagram which shows the example of the process progress at the time of the production | generation of a key. It is explanatory drawing which shows the smart meter which memorize | stores a 1st key and a 2nd key. It is explanatory drawing which shows the server which memorize | stores a 1st key and a 2nd key. It is a block diagram which shows the outline | summary of the encryption communication system of this invention. It is a schematic diagram which shows the terminal of this invention. It is a schematic diagram which shows the server of this invention.

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

  FIG. 1 is a block diagram showing an example of a cryptographic communication system according to the present invention. The cryptographic communication system of the present invention includes a terminal 1 and a server 2. In the present embodiment, a case where the terminal 1 is a smart meter and the smart meter transmits meter reading data to the server 2 will be described as an example. Further, a case where the server 2 is managed by an electric power company will be described as an example. However, the terminal 1 may be a terminal other than the smart meter, and may transmit data other than meter reading data to the server 2. The server 2 may also be a server that collects data other than meter reading data.

  For example, the smart meter 1 is arranged in a home or the like, and transmits meter reading data of power consumption in the home or the like to the server 2. At this time, the smart meter 1 encrypts and transmits the meter reading data, and the server 2 decrypts the received data. The server 2 may also transmit data to the smart meter 1. For example, since the power demand is increasing, the server 2 may transmit an instruction to reduce power consumption to the smart meter 1. Also in this case, the server 2 encrypts and transmits the data, and the smart meter 1 decrypts the received data. The data that the server 2 transmits to the smart meter 1 is not limited to the above data.

  The smart meter 1 and the server 2 hold a common key. The key is used for data encryption and decryption. For example, the smart meter 1 encrypts data with a held key and transmits the encrypted data to the server 2. The server 2 decrypts the received data by using a key common to the key used by the smart meter 1 for encryption.

  The smart meter 1 and the server 2 transmit a packet that includes encrypted data in the payload.

  The interval at which the meter reading data encrypted by the smart meter 1 is transmitted to the server 2 is, for example, 30 minutes.

  The smart meter 1 and the server 2 update the key at a predetermined timing using the meter reading data transmitted from the smart meter 1 to the server 2. The meter reading data used for updating the key is data that is not encrypted. Therefore, when the server 2 updates the key, the encrypted meter-reading data is decrypted, and the key is updated using the decrypted meter-reading data.

  The meter reading data used for the key update by the smart meter 1 and the server 2 is common, and the key update method is also common. Therefore, the keys held by the smart meter 1 and the server 2 remain common after the update.

  The server 2 may perform encrypted communication with a plurality of smart meters 1. At this time, the key is different for each smart meter 1.

  FIG. 2 is a block diagram illustrating a configuration example of the smart meter 1. The smart meter 1 includes a control unit 11, a key storage unit 12, an encryption operation unit 13, a decryption operation unit 14, a key update unit 15, a key generation unit 16, a device ID storage unit 17, an interface unit. 18.

  The control unit 11 controls the entire smart meter 1.

  The key storage unit 12 is a storage device that stores a key 30 used for data encryption and decryption. The data length of the key 30 is preferably 16 bytes or more, but may be less than 16 bytes. Hereinafter, a case where the key 30 is 16 bytes will be described as an example.

  The encryption calculation unit 13 encrypts the meter reading data given from the control unit 11 by using the key 30 and transmits the encrypted data to the server 2. Specifically, the encryption calculation unit 13 transmits a packet including the encrypted data in the payload to the server 2. The meter reading data provided from the control unit 11 may include not only the power consumption value but also information such as the device ID, date, date and time. The device ID is an ID unique to the smart meter 1.

  The decryption calculation unit 14 decrypts the data received from the server 2 using the key 30 and sends the decrypted data to the control unit 11. Specifically, the decryption calculation unit 14 decrypts data included in the payload of the packet received from the server 2 using the key 30.

  The key update unit 15 uses the meter reading data that has been transmitted to the server 2 most recently and that has not been encrypted when the key 30 stored in the key storage unit 12 is satisfied when a predetermined condition is satisfied. Update.

  Here, the predetermined condition is a condition in which a certain period has elapsed since the previous key 30 update, and the encryption calculation unit 13 does not transmit the meter reading data packet to the server 2 within the predetermined time. Each of the smart meter 1 and the server 2 preferably updates the key 30 each time a certain period elapses. However, if the encryption calculation unit 13 transmits the meter reading data packet and the update timing of the key 30 is close, the meter reading data used for updating the key 30 may be shifted in the smart meter 1 and the server 2. There is. Therefore, when a certain period has elapsed since the previous key 30 update and the condition that the encryption operation unit 13 does not transmit a packet (meter reading data) to the server 2 within a predetermined time is satisfied, The update unit 15 updates the key 30. The server 2 also updates the key 30 held by the server 2 when this condition is satisfied.

  The key generation unit 16 generates a key 30 and stores it in the key storage unit 12. Accordingly, the key 30 generated by the key generation unit 16 is subsequently updated by the key update unit 15.

  The device ID storage unit 17 is a storage device that stores a device ID.

  The interface unit 18 is an interface for communication with other devices (specifically, a traceability system described later). The traceability system has a device ID, production management information (for example, delivery date of used material, lot number, manufacturing date of each manufactured part, etc.) and communication identification information (for example, MAC (for each smart meter). Media Access Control) address) is stored in association with each other. The traceability system can trace the production status of the shipped smart meter 1. The communication identification information is information for identifying a device that performs communication during communication. For example, an address of a device that performs communication corresponds to the communication identification information. In the above description, the MAC address is given as an example of the communication identification information, but the communication identification information may be other than the MAC address.

  The communication between the smart meter 1 and the traceability system and the operation of the key generation unit 16 will be described later.

  The control unit 11, the encryption calculation unit 13, the decryption calculation unit 14, the key update unit 15, and the key generation unit 16 are realized by a CPU of a computer that operates according to a terminal program, for example. In this case, for example, the CPU reads a terminal program from a program recording medium such as a computer program storage device (not shown), and in accordance with the program, the control unit 11, the encryption operation unit 13, the decryption operation unit 14, and the key update The unit 15 and the key generation unit 16 may be operated. Alternatively, each of these elements may be realized by separate hardware.

  FIG. 3 is a block diagram illustrating a configuration example of the server 2. The server 2 includes a control unit 21, a key storage unit 22, an encryption operation unit 23, a decryption operation unit 24, and a key update unit 25.

  The control unit 21 controls the entire server 2.

  The key storage unit 22 is a storage device that stores the key 30. The key storage unit 22 of the server 2 stores a key common to the key 30 stored in the key storage unit 12 of the smart meter 1. However, as described above, the server 2 may perform encrypted communication with a plurality of smart meters 1. In this case, the key storage unit 22 stores individual keys 30 for each smart meter 1. The key storage unit 22 stores the key 30, the key 30, and the communication identification information of the smart meter 1 having a common key in association with each other.

  The key storage unit 22 stores the key 30 generated by the key generation unit 16 of the smart meter 1 in the initial state. Therefore, the key storage unit 12 of the smart meter 1 and the key storage unit 22 of the server 2 store the common key 30 in the initial state, and store the common key 30 even after the key update process.

  The encryption calculator 23 encrypts the data given from the controller 21 using the key 30 and transmits the encrypted data to the smart meter 1. Specifically, the encryption calculation unit 23 transmits a packet including the encrypted data in the payload to the smart meter 1.

  The decryption calculation unit 24 decrypts the data received from the smart meter 1 using the key 30 and sends the decrypted data to the control unit 21. Specifically, the decryption calculation unit 24 decrypts the data included in the payload of the packet received from the smart meter 1 using the key 30 common to the smart meter 1.

  The key update unit 25 is the meter reading data received from the smart meter 1 storing the key 30 most recently when the key 30 stored in the key storage unit 22 is satisfied when a predetermined condition is satisfied. Update using the meter reading data after decryption. This predetermined condition is the same as the predetermined condition already described.

  The key update method by the key update unit 15 of the smart meter 1 and the key update method by the key update unit 25 of the server 2 are common. Therefore, the smart meter 1 and the server 2 retain the common key 30 even after the update.

  The control unit 21, the encryption operation unit 23, the decryption operation unit 24, and the key update unit 25 are realized by a CPU of a computer that operates according to a server program, for example. In this case, for example, the CPU reads a server program from a program recording medium such as a computer program storage device (not shown), and in accordance with the program, the control unit 21, the encryption operation unit 23, the decryption operation unit 24, and the key update. The unit 25 may be operated. Alternatively, each of these elements may be realized by separate hardware.

  Next, each operation will be described.

  FIG. 4 is a sequence diagram illustrating an example of processing progress at the time of key update.

  The control unit 21 (see FIG. 3) of the server 2 transmits an inquiry as to whether or not the key 30 can be updated to the smart meter 1 after a certain period of time has elapsed since the previous key 30 update (see FIG. 3). Step S1). Note that the control unit 21 may cause the encryption operation unit 23 to encrypt the inquiry and cause the encryption operation unit 23 to transmit the inquiry. Alternatively, the control unit 21 may transmit the inquiry to the smart meter 1 without encrypting the inquiry. When the inquiry is encrypted and transmitted, the encryption operation unit 23 may encrypt the inquiry using the key 30 corresponding to the communication identification information of the smart meter 1 that is the inquiry transmission destination.

  The control unit 11 (see FIG. 2) of the smart meter 1 receives an inquiry from the server 2 as to whether the key 30 can be updated. When the inquiry is encrypted and transmitted / received, the decryption operation unit 14 of the smart meter 1 may decrypt the encrypted inquiry and send it to the control unit 11.

  The transmission / reception of an inquiry as to whether or not the key 30 can be updated means that a certain period has elapsed since the previous key 30 update. Therefore, the control unit 11 of the smart meter 1 can determine that a certain period has elapsed since the last update of the key 30 by receiving this inquiry.

  Next, the control unit 11 of the smart meter 1 determines whether or not the key 30 can be updated (step S2). Specifically, the control unit 11 determines whether or not to transmit a packet of meter reading data to the server 2 within a predetermined time (for example, 5 minutes) after receiving the inquiry. Then, the control unit 11 determines that the key 30 can be updated if the meter reading data packet is not transmitted to the server 2 within the predetermined time. Moreover, if the control part 11 transmits the packet of meter-reading data with respect to the server 2 within predetermined time, it will determine with the key 30 being unable to be updated.

  And the control part 11 of the smart meter 1 transmits the determination result in step S2 (whether or not the key 30 can be updated) to the server 2 as a response to the inquiry from the server 2 (step S3). Note that the control unit 11 may cause the encryption operation unit 13 to encrypt the response and cause the encryption operation unit 13 to transmit the response. Further, the control unit 11 may transmit the response to the server 2 without encrypting the response.

  The control unit 21 (see FIG. 3) of the server 2 receives a response to the inquiry from the smart meter 1. When the response is encrypted and transmitted / received, the decryption calculation unit 24 of the server 2 specifies the communication identification information of the smart meter 1 from the packet received as the response from the smart meter 1, and the communication identification information The response may be decrypted with the key 30 corresponding to, and sent to the control unit 21.

  When the control unit 21 of the server 2 receives a response indicating that the key 30 cannot be updated, the control unit 21 may perform the process of step S1 again after a certain time (for example, after 10 minutes).

  FIG. 4 shows a case where a response indicating that the key 30 can be updated is transmitted in step S3. The fact that the response indicating that the key 30 can be updated is transmitted / received in step S3 means that a certain period has elapsed since the previous key 30 update, and the encryption operation unit 13 sends the response to the server 2 within a predetermined time. This means that the condition that the meter reading data packet is not transmitted is satisfied.

  Therefore, when the control unit 11 of the smart meter 1 transmits a response indicating that the key 30 can be updated to the server 2, the control unit 11 causes the key update unit 15 to update the key 30. The key update unit 15 updates the key 30 stored in the key storage unit 12 according to the control unit 11 (step S4). The key update unit 15 updates the key 30 by performing a predetermined logical operation using the key 30 and the data before being encrypted, which is the meter reading data most recently transmitted to the server 2.

  Hereinafter, the update process of the key 30 will be described more specifically. In step S4, the key updating unit 15 extracts data corresponding to the data length of the key 30 (16 bytes in this example) from the head of the data that has been transmitted most recently to the server 2 and has not been encrypted. . This data is denoted as A. The key update unit 15 performs a predetermined logical operation using the key 30 and the data A, and sets the calculated result as the updated key 30. Here, a case has been described as an example where 16 bytes of data are extracted from the beginning of the meter reading data. The key update unit 15 may extract 16 bytes of data from a portion other than the beginning of the meter reading data as long as the data changes in the meter reading data. Further, in the above example, since the data length of the key 30 is 16 bytes, the case where data of 16 bytes is extracted is shown. However, the key update unit 15 can extract data A according to the data length of the key 30. The data length of data A is not limited to 16 bytes.

  When the data length of the meter reading data most recently transmitted to the server 2 and the data before encryption is less than the data length of the key 30, the key update unit 15 performs the update process as follows. Just do it. In this case, the meter reading data most recently transmitted to the server 2 and the data before encryption is B, and the data length is X bytes. The key updating unit 15 performs the above-described predetermined logical operation using the data for the first X bytes of the key 30 and the data B, and updates only the first X bytes of the key 30. In this example, only a part of the key 30 is updated. The key updating unit 15 may update the entire key 30 by repeating the logical operation between a part of the key 30 and the data B while shifting the position where the logical operation with the data B is performed in the key 30.

  In addition, when the control unit 21 of the server 2 receives a response indicating that the key 30 can be updated, a certain period has elapsed since the last update of the key 30, and the encryption operation unit 13 is within the predetermined time. 2, it is determined that the condition that the meter reading data packet is not transmitted is satisfied. Then, the control unit 21 of the server 2 causes the key update unit 25 to update the key 30. The key update unit 25 specifies the communication identification information of the smart meter 1 from the packet received as a response from the smart meter 1 according to the control unit 21, and updates the key 30 corresponding to the communication identification information (step S5). ). The key update unit 25 uses the data received most recently from the smart meter 1 determined by the communication identification information and decrypted, and the key 30 corresponding to the communication identification information, to determine a predetermined logic. The key 30 is updated by performing the calculation. This logical operation is a logical operation common to the logical operation performed in step S4. In addition, the key update process using the data and the key 30 is the same as the process described in step S4, and thus the description thereof is omitted here.

  The update process of the key 30 in steps S4 and S5 is the same process. Therefore, after the key 30 stored in the key storage unit 12 of the smart meter 1 and the key 30 stored in the key storage unit 22 of the server 2 together with the communication identification information of the smart meter 1 are updated, It is common. Therefore, the commonality between the key 30 on the smart meter 1 side and the key 30 on the server 2 side is always maintained.

  After steps S4 and S5, the smart meter 1 and the server 2 may confirm that the updated keys 30 held by the smart meter 1 and the server 2 are common, for example, as follows. For example, the control unit 11 of the smart meter 1 obtains a hash value of the updated key 30 using a predetermined hash function, and transmits it to the server 2. Similarly, the control unit 21 of the server 2 obtains the hash value of the updated key 30 using the same hash function as the hash function used by the smart meter 1 and transmits it to the smart meter 1. Both the control unit 11 of the smart meter 1 and the control unit 21 of the server 2 confirm that the transmitted hash value and the received hash value are the same, so that the updated key 30 is common. Confirm.

  In addition, the update method of the key 30 in step S4, S5 is not limited to the above-mentioned example, Other update methods may be used.

  Thereafter, when a certain period of time has elapsed since the key 30 was updated, the control unit 21 (see FIG. 3) of the server 2 executes Step S1 again. Therefore, the processes of steps S1 to S5 are repeated, and the smart meter 1 and the server 2 update the key 30 almost regularly. Since the key 30 is repeatedly updated in this way, the risk of eavesdropping on communication by a third party can be suppressed.

  FIG. 5 is a sequence diagram showing an example of processing progress when the smart meter 1 transmits meter reading data to the server 2.

  The control unit 11 (see FIG. 2) of the smart meter 1 acquires meter reading data periodically (for example, every 30 minutes) and sends it to the encryption calculation unit 13. In addition, the aspect in which the control part 11 acquires meter-reading data is not specifically limited. When the meter reading data is input from the control unit 11, the encryption calculation unit 13 of the smart meter 1 encrypts the meter reading data using the key 30 stored in the key storage unit 12 (step S11). In this example, it is assumed that the meter ID includes the device ID. Therefore, the device ID is also encrypted as part of the meter reading data.

  And the encryption calculating part 13 transmits the encrypted meter-reading data to the server 2 (step S12). Specifically, the encryption calculation unit 13 stores the encrypted meter reading data in the payload of the packet, and transmits the packet to the server 2. The header of this packet includes communication identification information of the smart meter that is the transmission source of the packet.

  When receiving the packet transmitted in step S12, the decryption calculation unit 24 (see FIG. 3) of the server 2 extracts communication identification information and encrypted meter-reading data from the packet. Then, the decoding calculation unit 24 reads the key 30 corresponding to the communication identification information from the key storage unit 22 and uses the key 30 to decode the meter reading data. Furthermore, the decoding calculation unit 24 sends the decoded meter reading data to the control unit 21 (step S13).

  Through the above processing, the smart meter 1 transmits the encrypted meter reading data to the server 2, and the server 2 can decrypt the meter reading data.

  FIG. 6 is a sequence diagram illustrating an example of processing progress when the server 2 transmits data to the smart meter 1. Note that examples of data that the server 2 transmits to the smart meter 1 include, for example, an instruction to reduce power consumption because power demand is increasing, but is not limited to this example.

  When data to be transmitted to the smart meter 1 is generated, the control unit 21 of the server 2 sends the data to the encryption calculation unit 23. At this time, the control unit 21 also sends the communication identification information of the smart meter 1 as a transmission destination to the encryption calculation unit 23. When the data and the communication identification information are input from the control unit 21, the encryption calculation unit 23 of the server 2 reads the key 30 corresponding to the communication identification information from the key storage unit 22, and uses the key 30. Data is encrypted (step S21).

  Then, the encryption operation unit 23 stores the encrypted data in the payload of the packet, and transmits the packet to the smart meter 1 that is the transmission destination (step S22).

  When receiving the packet transmitted in step S22, the decryption calculation unit 14 (see FIG. 2) of the smart meter 1 extracts the encrypted data from the packet. Then, the decryption calculation unit 14 reads the key 30 from the key storage unit 12 and decrypts the data using the key 30. Furthermore, the decoding calculation unit 14 sends the decoded data to the control unit 11 (step S23).

  Next, the processing progress when the key 30 is first generated will be described. The key 30 in the initial state is generated when the manufacture of the smart meter 1 is completed. When the manufacture of the smart meter 1 is completed, the smart meter 1 is connected to the traceability system. FIG. 7 is a schematic diagram showing a state in which the smart meter 1 is connected to the traceability system. The same elements as those shown in FIG. 2 are denoted by the same reference numerals as those in FIG.

  The traceability system 40 and the smart meter 1 are connected in a manner in which the confidentiality of communication between the traceability system 40 and the smart meter 1 is maintained. For example, the traceability system 40 and the smart meter 1 are preferably connected via a wired dedicated line. However, as long as the confidentiality of communication between the traceability system 40 and the smart meter 1 is maintained, communication may be performed in other modes such as wireless communication.

  The traceability system 40 is managed by the manufacturer of the smart meter 1. The device ID, production management information, and communication identification information (for example, MAC address) are associated with each smart meter and stored in the traceability system 40. As the manufacturing process of a certain smart meter 1 proceeds, production management information, such as the delivery date of the used material, the lot number, and the manufacturing date of each manufactured part, is accumulated in the traceability system 40 for the smart meter 1. Such production management information is unique to each smart meter 1. That is, there is no other smart meter having the same production management information as a certain smart meter. Note that the communication identification information is also unique to each smart meter 1.

  The key generation unit 16 of the smart meter 1 generates a key 30 using production management information unique to the smart meter 1.

  FIG. 8 is a sequence diagram illustrating an example of processing progress when the key 30 is generated.

  When the smart meter 1 is connected to the traceability system 40, the traceability system 40 requests a device ID from the smart meter 1 (step S51).

  When the control unit 11 of the smart meter 1 receives the request for the device ID, it reads the device ID from the device ID storage unit 17 and transmits the device ID to the traceability system 40 via the interface unit 18 (step S52).

  When receiving the device ID, the traceability system 40 transmits production management information associated with the device ID to the smart meter 1 (step S53). As described above, this production management information is information unique to the smart meter 1.

  When the control unit 11 of the smart meter 1 receives the production management information of the smart meter 1, the control unit 11 sends the production management information to the key generation unit 16 and causes the key generation unit 16 to generate the key 30. The key generation unit 16 generates the key 30 using the production management information input from the control unit 11 according to the control unit 11 (step S54). The method by which the key generation unit 16 generates the key 30 using the production management information is not particularly limited. For example, the key generation unit 16 may generate the key 30 by passing the production management information through a pseudo random number generator.

  The key generation unit 16 stores the key 30 generated in step S54 in the key storage unit 12, and notifies the control unit 11 that the generation of the key 30 is completed (step S55).

  Then, the control part 11 reads the key 30 from the key memory | storage part 12, and transmits the key 30 to the traceability system 40 via the interface part 18 (step S56).

  The traceability system 40 stores the key 30 received in step S56, the device ID received in step S52, and the communication identification information corresponding to the device ID in association with each other (step S57).

  After step S57, the traceability system 40 and the smart meter 1 are disconnected.

  The operations of steps S51 to S57 are performed for each smart meter that has been manufactured. As a result, each smart meter 1 stores a unique key 30 in the key storage unit 12, and the traceability system 40 stores information that associates the device ID, the communication identification information, and the key 30 for each smart meter 1. Remember.

  As described above, the key generation unit 16 generates the key 30 using the production management information unique to the smart meter 1. Accordingly, it is possible to prevent a plurality of smart meters 1 from storing the same key 30.

  Assume that a random number is generated for each smart meter 1 and the key generation unit 16 generates the key 30 using the random number. In this case, the same random number can be generated in different smart meters 1. As a result, different smart meters 1 may have the same key 30. On the other hand, in the above-described operation, the key generation unit 16 generates the key 30 using the production management information unique to the smart meter 1, so that different smart meters 1 cannot have the same key 30.

  The administrator (manufacturer of the smart meter 1) of the traceability system 40 reads the set of the device ID, the communication identification information, and the key 30 obtained for each smart meter from the traceability system 40, and the administrator of the server 2 (this book) In the example, it is sent to the electric power company. For example, the administrator of the traceability system 40 mails a recording medium such as a CD-ROM in which a set of the device ID, communication identification information, and key 30 for each smart meter is recorded to an electric power company. The power company that has received the set of device ID, communication identification information, and key 30 for each smart meter stores the set of communication identification information for each smart meter and key 30 in the key storage unit 22 of the server 2.

  As a result, each smart meter 1 is in a state in which the key 30 in the initial state is stored. Moreover, the server 2 will be in the state which memorize | stored the communication identification information and the key 30 of the initial state correspondingly for every smart meter.

  When the smart meter 1 is shipped and communication between the smart meter 1 and the server 2 is started, the smart meter 1 and the server 2 respectively store by the operations of the above-described steps S1 to S5 (see FIG. 4). The common key 30 is updated. Therefore, as already explained, the risk of wiretapping of communication by a third party can be suppressed.

Next, a modification of the above embodiment will be described.
Hereinafter, transmission of data from the smart meter 1 to the server 2 is referred to as uplink communication. In addition, transmission of data from the server 2 to the smart meter 1 is referred to as downlink communication.

  The key used for data encryption and decryption in uplink communication and the key used for data encryption and decryption in downlink communication may be different keys. Hereinafter, a key used for data encryption and decryption in upstream communication is referred to as a first key. A key used for data encryption and decryption in downstream communication is referred to as a second key.

  FIG. 9 is an explanatory diagram showing a smart meter that stores a first key and a second key. The same elements as those shown in FIG. 2 are denoted by the same reference numerals as those in FIG. FIG. 10 is an explanatory diagram showing a server that stores the first key and the second key. The same elements as those shown in FIG. 3 are denoted by the same reference numerals as those in FIG.

  The key storage unit 12 of the smart meter 1 and the key storage unit 22 of the server 2 store a common key as the first key 31. Similarly, the key storage unit 12 of the smart meter 1 and the key storage unit 22 of the server 2 store a common key as the second key 32.

  The key storage unit 22 of the server 2 stores communication identification information, a first key 31, and a second key 32 in association with each smart meter.

  The first key 31 is different for each smart meter, and similarly, the second key 32 is also different for each smart meter.

  In step S54 (see FIG. 8), the key generation unit 16 of the smart meter 1 generates two keys (first key 31) using two types of key generation methods when generating a key using production management information. And the second key 32) may be generated.

  When the key update unit 15 of the smart meter 1 updates the key using the data before being encrypted, which is the meter reading data most recently transmitted to the server 2 in step S4 (see FIG. 4), The key 31 and the second key 32 may be updated.

  Similarly, when the key update unit 25 of the server 2 updates the key using the data that has been received from the smart meter 1 and decrypted in step S5 (see FIG. 4), the first update is performed. The key 31 and the second key 32 may be updated.

  In steps S4 and S5, the logical operation for updating the first key 31 and the logical operation for updating the second key 32 may be different. However, the logical operation for the smart meter 1 to update the first key 31 and the logical operation for the server 2 to update the first key 31 are common. The logical operation for the smart meter 1 to update the second key 32 and the logical operation for the server 2 to update the second key 32 are common.

  As a result, even if the first key 31 and the second key 32 are updated, the commonity of the first key 31 is maintained between the smart meter 1 and the server 2, and the second key 32 is common. Sex is also maintained.

  When performing upstream communication, the encryption calculation unit 13 of the smart meter 1 encrypts the meter reading data using the first key 31 in step S11 (see FIG. 5). And the decoding calculation part 24 of the server 2 decodes meter-reading data using the 1st key 31 by step S13 (refer FIG. 5).

  When performing downlink communication, the encryption operation unit 23 of the server 2 encrypts data using the second key 32 in step S21 (see FIG. 6). Then, the decryption calculation unit 14 of the smart meter 1 decrypts the data using the second key 32.

  Other operations are the same as those already described.

  In the above modification, the key used for encryption and decryption in the upstream communication (first key 31) and the key used for encryption and decryption in the downstream communication (second key 32) are separated. The risk of wiretapping of communications by the three parties can be further suppressed.

  In the description of the above embodiment, the case has been described in which the device ID is included in the meter reading data and the device ID is encrypted as part of the meter reading data. The smart meter 1 may transmit the device ID and the encrypted meter reading data to the server 2 without including the device ID in the meter reading data and without encrypting the device ID. And the server 2 may specify the key for decoding meter-reading data based on apparatus ID.

  In this case, the storage unit 22 of the server 2 stores a set of device ID and key for each smart meter 1. For example, when the power company receives a set of device ID, communication identification information, and key 30 for each smart meter from the manufacturer of the smart meter 1, the power company sets the set of device ID and key 30 for each smart meter to the server 2. May be stored in the key storage unit 22.

  Then, in step S12 (see FIG. 5), the encryption calculation unit 13 of the smart meter 1 stores the encrypted meter reading data in the payload of the packet, and when the packet is transmitted to the server 2, the device ID is For example, it may be stored in the option part in the header of the packet. The same applies to the case where the smart meter 1 encrypts and transmits the response to the inquiry from the server 2 in step S3 (see FIG. 4).

  When receiving a packet in which encrypted meter reading data or the like is stored in the payload, the decryption calculation unit 24 of the server 2 extracts a device ID from the header of the packet, and stores a key corresponding to the device ID in the storage unit 22. The data read from and encrypted with the key may be decrypted.

  Next, the outline of the present invention will be described. FIG. 11 is a block diagram showing an outline of the cryptographic communication system of the present invention. The cryptographic communication system of the present invention includes a terminal 1 that transmits data and a server 2 that receives data.

  The terminal 1 and the server 2 each store a common key used for data encryption and decryption. Then, the terminal 1 and the server 2 update the key using data transmitted from the terminal 1 to the server 2 when a predetermined condition is satisfied.

  With such a configuration, eavesdropping by a third party can be prevented.

  FIG. 12 is a schematic diagram showing a terminal of the present invention. The terminal 1 of the present invention transmits data to the server. The terminal 1 is a key used for data encryption and decryption, and stores a key common to the server. When a predetermined condition is satisfied, the terminal 1 updates the key using data transmitted from the terminal 1 to the server.

  FIG. 13 is a schematic diagram showing a server of the present invention. The server 2 of the present invention receives data from the terminal. The server 2 is a key used for data encryption and decryption, and stores a key common to the terminal. The server 2 updates the key using data transmitted from the terminal to the server 2 when a predetermined condition is satisfied.

  A part or all of the above embodiments can be described as in the following supplementary notes, but is not limited to the following.

(Supplementary note 1) A terminal that transmits data to a server and is a key used for data encryption and decryption, stores a key common to the server, and when a predetermined condition is satisfied, A terminal, wherein the key is updated using data transmitted from the terminal to the server.

(Supplementary note 2) The terminal according to supplementary note 1, wherein the key is updated every time a certain period elapses.

(Supplementary note 3) Supplementary note for updating the key when a certain period has passed since the previous key update and the condition that the terminal does not transmit data encrypted with the key within a predetermined time is satisfied The terminal according to 1 or Appendix 2.

(Supplementary note 4) The terminal according to any one of supplementary note 1 to supplementary note 3, wherein data encrypted using a key is transmitted to a server together with communication identification information of the terminal.

(Supplementary note 5) The terminal according to any one of Supplementary note 1 to Supplementary note 3, wherein data encrypted using a key is transmitted to a server together with a device ID that is unique to the terminal and is not encrypted. .

(Supplementary Note 6) Key storage means for storing a key used for data encryption and decryption, encryption means for encrypting data using the key, and transmitting the encrypted data to the server, and a predetermined condition Supplementary Note 1 to Supplementary Note 1 further comprising: key update means for updating the key stored in the key storage means using the data that has been transmitted to the server and is not yet encrypted when the key is satisfied. The terminal according to any one of 5.

(Supplementary note 7) The key storage means stores the first key and the second key as keys, and the encryption means encrypts the data using the first key, and sends the encrypted data to the server. Decrypting means for transmitting and decrypting data received from the server using the second key, and the key updating means, when a predetermined condition is met, the first key and the second key The terminal according to appendix 6, wherein the key is updated using data that has been transmitted to the server most recently and has not been encrypted.

(Supplementary note 8) The key common to the server that the terminal stores in the initial state is a key generated based on the production management information of the terminal at the time of manufacture of the terminal. The listed terminal.

(Supplementary note 9) The terminal according to any one of Supplementary note 1 to Supplementary note 8, wherein the terminal device is a smart meter.

(Supplementary Note 10) A server that receives data from a terminal, is a key used for data encryption and decryption, stores a key common to the terminal, and when a predetermined condition is satisfied, the terminal A server, wherein the key is updated using data transmitted to the server.

(Additional remark 11) The server of Additional remark 10 which updates a key whenever a fixed period passes.

(Supplementary note 12) The key is updated when a certain period has passed since the previous key update and the condition that the terminal does not transmit the data encrypted with the key of the terminal within a predetermined time is satisfied. The server according to Supplementary Note 10 or Supplementary Note 11.

(Supplementary note 13) For each terminal, the communication identification information of the terminal, the key of the terminal and the common key are stored in association with each other, and the received communication identification is received when the encrypted data and the communication identification information are received. The server according to any one of appendix 10 to appendix 12, wherein the data is decrypted using a key corresponding to the information.

(Supplementary note 14) When each terminal stores a device ID unique to the terminal, a key of the terminal, and a common key in association with each other, and receives encrypted data and an unencrypted device ID The server according to any one of appendix 10 to appendix 12, wherein the data is decrypted using a key corresponding to the received device ID.

(Supplementary Note 15) Key storage means for storing a key used for data encryption and decryption, decryption means for decrypting data received from a terminal using the key, and when a predetermined condition is satisfied, The key stored in the key storage means is data received most recently from the terminal, and key update means for updating the data using decrypted data. Server.

(Supplementary Note 16) The key storage means stores the first key and the second key as keys, and the decryption means decrypts the data received from the terminal using the first key, and the second key An encryption unit that encrypts data using a key and transmits the encrypted data to the terminal; and the key update unit includes the first key and the second key when a predetermined condition is satisfied. The server according to supplementary note 15, wherein the key is updated using data decrypted recently from the terminal.

(Supplementary Note 17) The key common to the terminal stored in the initial state by the server is a key generated based on the production management information of the terminal at the time of manufacture of the terminal. The listed server.

(Supplementary Note 18) A terminal for transmitting data and a server for receiving the data are provided, and each of the terminal and the server stores a common key used for data encryption and decryption and satisfies a predetermined condition. And the key is updated using the data transmitted from the terminal to the server.

(Supplementary note 19) The cryptographic communication system according to supplementary note 18, wherein each of the terminal and the server updates the key each time a certain period elapses.

(Supplementary note 20) When the terminal and the server each satisfy a condition that a certain period has elapsed since the last key update and the terminal does not transmit the data encrypted with the key within a predetermined time The encryption communication system according to appendix 18 or appendix 19, wherein the key is updated.

(Supplementary note 21) The terminal transmits the data encrypted using the key to the server together with the communication identification information of the terminal, and the server shares, for each terminal, the communication identification information of the terminal and the key of the terminal. Any one of appendix 18 to appendix 20 that stores the key in association with each other and decrypts the data using the key corresponding to the received communication identification information when the encrypted data and the communication identification information are received. The cryptographic communication system according to claim 1.

(Supplementary note 22) The terminal transmits the data encrypted by using the key to the server together with the device ID that is unique to the terminal and is not encrypted. Additional information for storing the ID and the key of the terminal in association with each other and decrypting the data using the key corresponding to the received device ID when the encrypted data and the device ID are received The cryptographic communication system according to any one of 18 to appendix 20.

(Supplementary Note 23) The terminal has terminal-side key storage means for storing a key used for data encryption and decryption, and terminal-side encryption for encrypting data using the key and transmitting the encrypted data to the server And a terminal that updates the key stored in the terminal-side key storage means using the data most recently transmitted to the server and before being encrypted when a predetermined condition is satisfied Side key update means, and the server includes server side key storage means for storing a key common to the key, server side decryption means for decrypting data received from the terminal using the key, and A server-side key that updates the key stored in the server-side key storage means by using the data received most recently from the terminal and decrypted when predetermined conditions are satisfied Cryptographic communication system according to any one of Appendices 22 Appendixes 18 and a new unit.

(Supplementary Note 24) The terminal-side key storage means and the server-side key storage means store the first key and the second key as keys, and the terminal-side encryption means encrypts data using the first key. And the encrypted data is transmitted to the server, the server-side decrypting means decrypts the data received from the terminal using the first key, and the server uses the second key to And the server side encryption means for transmitting the encrypted data to the terminal, the terminal decrypting the data received from the server using the second key. The terminal side key update means includes the data that has been transmitted to the server most recently and is not encrypted when the predetermined condition is satisfied. Update using server side key The new means updates the first key and the second key using the data that has been received from the terminal and decrypted when the predetermined condition is satisfied. 24. The cryptographic communication system according to 23.

(Supplementary note 25) The common key stored in the initial state by the terminal and the server is any one of Supplementary note 18 to Supplementary note 24, which is a key generated based on the production management information of the terminal when the terminal is manufactured. Cryptographic communication system.

(Supplementary note 26) The cryptographic communication system according to any one of supplementary note 18 to supplementary note 25, wherein the terminal is a smart meter.

(Supplementary note 27) A terminal that transmits data and a server that receives the data each store a common key used for data encryption and decryption, and when a predetermined condition is satisfied, the terminal An encryption communication method, wherein the key is updated using data transmitted to the server.

(Supplementary note 28) A key used for data encryption and decryption, comprising a key storage means for storing a key common to a server, and a terminal program mounted on a computer for transmitting data to the server The computer encrypts data using the key and transmits the encrypted data to the server, and when a predetermined condition is satisfied, the data is stored in the key storage means. A terminal program for executing a key update process for updating a key that has been transmitted to the server using data before being encrypted and before encryption.

(Supplementary note 29) A key used for data encryption and decryption, comprising a key storage means for storing a key common to a terminal, and a server program installed in a computer for receiving data from the terminal, The computer receives the decryption process for decrypting the data received from the terminal using the key, and the key stored in the key storage unit when the predetermined condition is satisfied. A server program for executing key update processing for updating received data that has been decrypted.

  The present invention is preferably applied to an encryption communication system that performs communication by encrypting data.

1 terminal (smart meter)
2 server 11 control unit 12 key storage unit 13 encryption operation unit 14 decryption operation unit 15 key update unit 16 key generation unit 17 device ID storage unit 18 interface unit 21 control unit 22 key storage unit 23 encryption operation unit 24 decryption operation unit 24 25 Key update part

Claims (29)

A terminal that transmits data to a server,
A key used for data encryption and decryption, storing a key common to the server,
A terminal, wherein when a predetermined condition is satisfied, the key is updated using data transmitted from the terminal to the server. The terminal according to claim 1, wherein the key is updated every time a certain period elapses. The key is updated when a certain period has elapsed since the previous key update and the condition that the terminal does not transmit the data encrypted with the key within a predetermined time is satisfied. Item 3. The terminal according to Item 2. The terminal according to any one of claims 1 to 3, wherein data encrypted using the key is transmitted to a server together with communication identification information of the terminal. The terminal according to any one of claims 1 to 3, wherein the data encrypted using the key is transmitted to the server together with a device ID that is unique to the terminal and is not encrypted. . Key storage means for storing keys used for data encryption and decryption;
Encryption means for encrypting data using the key and transmitting the encrypted data to a server;
And a key update unit that updates the key stored in the key storage unit using data that has been transmitted to the server and that has not been encrypted when a predetermined condition is satisfied. The terminal according to any one of claims 1 to 5. The key storage means stores the first key and the second key as keys,
The encryption means encrypts the data using the first key, transmits the encrypted data to the server,
Decryption means for decrypting data received from the server using the second key;
The key updating means updates the first key and the second key using data that has been transmitted to the server most recently and has not been encrypted when a predetermined condition is satisfied. The terminal according to claim 6. The key that is common to the server that the terminal stores in the initial state is a key that is generated based on the production management information of the terminal at the time of manufacturing the terminal. The listed terminal. The terminal according to any one of claims 1 to 8, wherein the terminal device is a smart meter. A server that receives data from a terminal,
A key used for data encryption and decryption, storing a common key with the terminal,
The server updates the key using data transmitted from the terminal to the server when a predetermined condition is satisfied. The server according to claim 10, wherein the key is updated every time a certain period elapses. The key is updated when a certain period has elapsed since the previous key update and the condition that the terminal does not transmit data encrypted with the key of the terminal within a predetermined time is satisfied. The server according to claim 11. For each terminal, the communication identification information of the terminal, the key of the terminal and the common key are stored in association with each other,
The server according to any one of claims 10 to 12, wherein when the encrypted data and communication identification information are received, the data is decrypted using a key corresponding to the received communication identification information. . For each terminal, a device ID unique to the terminal, a key of the terminal and a common key are stored in association with each other,
The encrypted data and the unencrypted device ID are decrypted using a key corresponding to the received device ID when receiving the encrypted data and the unencrypted device ID. The listed server. Key storage means for storing keys used for data encryption and decryption;
Decryption means for decrypting data received from the terminal using the key;
A key update unit configured to update a key stored in the key storage unit by using the data received most recently from the terminal and decrypted when a predetermined condition is satisfied. The server according to any one of claims 10 to 14. The key storage means stores the first key and the second key as keys,
The decrypting means decrypts the data received from the terminal using the first key,
Encryption means for encrypting data using the second key and transmitting the encrypted data to the terminal;
The key updating means updates the first key and the second key using data that has been received from the terminal and decrypted, when a predetermined condition is satisfied. Item 16. The server according to Item 15. The key common to the terminal stored in the initial state by the server is a key generated based on the production management information of the terminal at the time of manufacturing the terminal. The listed server. A device that sends data,
A server for receiving the data,
The terminal and the server are respectively
Store a common key used to encrypt and decrypt data,
An encryption communication system, wherein when the predetermined condition is satisfied, the key is updated using data transmitted from the terminal to the server. The terminal and server are
The cryptographic communication system according to claim 18, wherein the key is updated each time a certain period elapses. The terminal and server are
19. The key is updated when a certain period has elapsed since the previous key update and the condition that the terminal does not transmit data encrypted with the key within a predetermined time is satisfied. Item 20. A cryptographic communication system according to Item 19. The terminal
Send the data encrypted with the key to the server along with the communication identification information of the terminal,
The server
For each terminal, the communication identification information of the terminal, the key of the terminal and the common key are stored in association with each other,
The encryption according to any one of claims 18 to 20, wherein when the encrypted data and the communication identification information are received, the data is decrypted using a key corresponding to the received communication identification information. Communications system. The terminal
The data encrypted using the key is transmitted to the server together with a device ID that is unique to the terminal and is not encrypted,
The server
For each terminal, the device ID of the terminal, the key of the terminal and the common key are stored in association with each other,
The encrypted communication system according to any one of claims 18 to 20, wherein when the encrypted data and the device ID are received, the data is decrypted using a key corresponding to the received device ID. . The terminal
Terminal-side key storage means for storing keys used for data encryption and decryption;
Terminal-side encryption means for encrypting data using the key and transmitting the encrypted data to the server;
When a predetermined condition is satisfied, a terminal-side key update that updates the key stored in the terminal-side key storage means using data that has been transmitted to the server and that has not been encrypted. Means,
The server
Server-side key storage means for storing a key common to the key;
Server-side decryption means for decrypting data received from the terminal using the key;
Server-side key update that updates the key stored in the server-side key storage means using the data received most recently from the terminal and decrypted when the predetermined condition is satisfied The cryptographic communication system according to any one of claims 18 to 22, further comprising: means. The terminal side key storage unit and the server side key storage unit store the first key and the second key as keys,
The terminal-side encryption means encrypts the data using the first key, transmits the encrypted data to the server,
The server side decryption means decrypts the data received from the terminal using the first key,
The server
Server-side encryption means for encrypting data using the second key and transmitting the encrypted data to the terminal;
The terminal
Terminal-side decryption means for decrypting data received from the server using the second key;
The terminal-side key update means uses the data before the first key and the second key that have been transmitted to the server before encryption when a predetermined condition is satisfied. Updated,
The server-side key update means uses the data that has been received from the terminal and is decrypted with the first key and the second key when the predetermined condition is satisfied. The cryptographic communication system according to claim 23, which is updated. The common key which a terminal and a server memorize | store in an initial state is a key produced | generated based on the production management information of the said terminal at the time of manufacture of a terminal, The any one of Claims 18-24 Cryptographic communication system. The encryption communication system according to any one of claims 18 to 25, wherein the terminal is a smart meter. A terminal that transmits data and a server that receives the data,
Store a common key used to encrypt and decrypt data,
The encryption communication method, wherein when the predetermined condition is satisfied, the key is updated using data transmitted from the terminal to the server. A key used for data encryption and decryption, comprising a key storage means for storing a key common to a server, a terminal program installed in a computer for transmitting data to the server,
In the computer,
An encryption process for encrypting data using the key, and transmitting the encrypted data to the server; and
When a predetermined condition is satisfied, a key update process is executed in which the key stored in the key storage unit is updated using data that has been transmitted to the server most recently and has not been encrypted. Program for the terminal. A key used for data encryption and decryption, comprising a key storage means for storing a key common to a terminal, and a server program installed in a computer that receives data from the terminal,
In the computer,
A decryption process for decrypting data received from the terminal using the key; and
To update a key stored in the key storage means by using the data received most recently from the terminal and decrypted when a predetermined condition is satisfied. Server program.

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