JP2020036145A - Data transmission source device, data transmission destination device, data processing system, and data processing method - Google Patents

Abstract

To provide a data transmission source device that encrypts and decrypts communication data using key data updated for each transmission and reception.SOLUTION: A data transmission source device 10 is connected to a data transmission destination device 20 having time-series data 210, and transmits the encrypted latest value obtained by encrypting the latest value to the data transmission destination device 20. The data transmission source device 10 includes a key generation unit 102 that creates an encryption key 420 used for encryption on the basis of a previous value 113 and a value 114 before the previous value for the latest value 112 to be encrypted, an encryption unit 104 that encrypts the latest value 112 to create an encrypted latest value 440 by using the encryption key 420, and a transmitting unit 105 that transmits the encrypted latest value 440, and each time the encrypted latest value 440 is transmitted, the encryption key generation unit 102 creates an encryption key.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a data transmission source device, a data transmission destination device, a data processing system, and a data processing method.

  In recent years, everything has come to be connected to networks, and security measures are urgently required for embedded devices such as various control devices and measuring devices, information home appliances, and mobile phones. As a security measure, for example, a public key encryption system that uses a public key for encryption and a private key for decryption as a technology for encrypting and communicating data so that a third party cannot view communication data by unauthorized means A common key cryptosystem using a common key for encryption and decryption is generally known. Also, when a third party rewrites (falsifies) the content of the communication data, it can be detected by a digital signature based on a public key cryptosystem. However, embedded devices are often dedicated machines dedicated to a certain purpose, and have lower CPU (Central Processing Unit) processing capacity and less memory resources than general-purpose PCs. In many cases, complicated arithmetic processing cannot be used. Further, even when the public key cryptosystem can be used, there are problems such as production control of the public key and the private key, and how to share and exchange the key between the data transmission source and the data transmission destination embedded device. Similarly, the common key cryptosystem also has a problem in sharing and exchanging a common key.

  For a system that transmits and receives data between embedded devices (measuring devices), it samples electrical quantities, calculates harmonic current data, creates key data from this harmonic current data, and changes the key data for each transmission and reception for authentication. A technique for creating tag data is known (see Patent Document 1).

JP 2013-197759 A

  However, in Patent Literature 1, key data is created based on harmonic current data. However, in order to acquire harmonic current data, it is usually necessary to perform sampling at a higher speed than a sampling cycle of measurement data to be performed. Requires a high-level calculation process and load.

  One embodiment of the present invention has been made in view of the above points, creates key data based on data held by an apparatus, encrypts communication data using key data updated for each transmission and reception, and encrypts communication data. The purpose is to decrypt.

  In order to achieve the above object, an embodiment of the present invention is directed to a data transmission source connected to a data transmission destination device having past data and transmitting encrypted latest data obtained by encrypting latest data to the data transmission destination device. An apparatus, comprising: a time-series data storage unit that stores data in time series; and an encryption key generation unit that creates an encryption key used for encryption based on the past data stored in the time-series data storage unit. An encryption unit that creates the latest encrypted data using the encryption key created by the encryption key generation unit; and stores the latest encrypted data created by the encryption unit in the data. A transmission unit for transmitting to the destination device, wherein the encryption key generation unit generates the encryption key every time the latest data is obtained, and the encryption unit includes the key generation unit Creates the encryption key Each time the encrypted latest data is encrypted, the encrypted latest data is created, and the transmission unit creates the encrypted latest data every time the encryption unit creates the encrypted latest data. Data to the destination device.

  According to an embodiment of the present invention, it is not necessary to transfer and manage a key between devices, and data transmitted and received between devices is data that is encrypted using a different key each time. Can be expected to prevent.

FIG. 1 is a diagram illustrating an example of a system configuration of a data processing system according to a first embodiment. FIG. 2 is a diagram illustrating an example of a hardware configuration of a data transmission source device according to the first embodiment. FIG. 3 is a diagram illustrating an example of a hardware configuration of a data transmission destination device according to the first embodiment. FIG. 2 is a diagram illustrating an example of a functional configuration of the data processing system according to the first embodiment. 5 is a flowchart illustrating an example of a process from acquisition of past data to transmission in the data transmission source device according to the first embodiment. 5 is a flowchart illustrating an example of a process of storing the latest data in the data transmission destination device according to the first embodiment. 5 is a flowchart illustrating an example of a process of creating an encryption key in the data transmission source device according to the first embodiment. 6 is a flowchart illustrating an example of a process for creating a decryption key in the data transmission destination device according to the first embodiment. FIG. 2 is a diagram illustrating an example of a functional configuration of the data processing system according to the first embodiment. FIG. 2 is a diagram illustrating an example of a functional configuration of the data processing system according to the first embodiment. FIG. 4 is a diagram illustrating an example of a device ID table in the data transmission destination device according to the first embodiment. FIG. 3 is a diagram illustrating an example of a communication packet in the data transmission source device according to the first embodiment.

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

[First embodiment]
<System configuration>
First, a system configuration of a data processing system 1 according to the present embodiment will be described with reference to FIG. FIG. 1 is a diagram illustrating an example of a system configuration of a data processing system 1 according to the present embodiment.

  As shown in FIG. 1, a data processing system 1 according to the present embodiment includes a data transmission source device 10 for transmitting data and a data transmission destination device 20 for receiving data. They are communicably connected via a network N such as a telephone network. The data transmission destination device 10 and the data transmission source device 20 may be communicably connected via short-range wireless communication such as Bluetooth (registered trademark) or a dedicated communication line or a common bus.

  The data transmission source device 10 is a data processing device that collects various measurement data from sensors and the like regularly or when necessary, and accumulates the measurement data in the collected time series, and is a measurement device classified as an embedded device. The data transmission source device 10 includes a latest data provision processing unit 100 and a time-series data storage unit 110.

  The time series data storage unit 110 stores various measurement data in a time series. Hereinafter, of the measurement data accumulated in a time series, the latest measurement data is referred to as latest data (= latest value) 112, and the past measurement data is referred to as past data 111. Among the past data 111, the measurement data collected just before the timing of collecting the latest data is referred to as previous data (= previous value), and the measurement data collected two times before is referred to as pre-last data (= pre-last value).

  Further, the latest data providing processing unit 100 encrypts the latest data 112 by using a method of authenticated encryption (AE: Authenticated Encryption or AEAD: Authenticated Encryption with Associated Data). Then, the latest data provision processing unit 100 provides the latest data after the encryption (the latest encrypted data and the authentication tag described later) to the data transmission destination device 20. At this time, the latest data provision processing unit 100 creates an encryption key based on the past data 111, and then encrypts the latest data 112 using the encryption key. The authentication tag is also called a message authentication code (MAC), and verifies the integrity of the latest data after encryption (that is, that the latest data after encryption is not falsified). Information.

  The data transmission destination device 20 is, for example, an embedded device such as a measuring device or a control device, or a server on a cloud. The data transmission destination device 20 includes a latest data storage processing unit 200 and a time-series data storage unit 210.

  The latest data storage processing unit 200 decrypts the encrypted latest data and the authentication tag provided from the data transmission source device 10 by using an authentication-assisted encryption method, and creates the latest data 470. At this time, the latest data storage processing unit 200 creates a decryption key based on the past data 111 of the data transmission source device 20, and then decrypts the encrypted latest data using the decryption key. Further, the past data used for creating the encryption key and the decryption key is extracted from the past data corresponding to the target latest data. The same measurement data is used in the data transmission source device and the data transmission destination device (that is, the values are the same).

  As described above, in the data processing system 1 according to the present embodiment, the data transmission source device 10 provides the latest data 112 to the data transmission destination device 20 by using the authentication-assisted encryption method. Thereby, in the data processing system 1 according to the present embodiment, for example, even if a malicious third party intercepts the latest encrypted data on the network, it is difficult to decrypt the data, and furthermore, the malicious third party transmits the incorrect latest data. Even if the data is sent to the destination device 20, it is possible to prevent a situation in which the data is written (that is, a situation in which incorrect latest data is stored in the time-series data storage unit).

  At this time, in the data processing system 1 according to the present embodiment, an encryption key is created based on the past data 111 included in the data transmission source device 10 and based on the past data 111 included in the data transmission destination device 20. Create a decryption key. Thus, in the data processing system 1 according to the present embodiment, the data transmission destination device 10 and the data transmission source device 20 do not need to manage the encryption key and the decryption key, respectively. Further, in the data processing system 1 according to the present embodiment, the encryption key and the decryption key can be updated every time the latest data is obtained.

  In the present embodiment, the case where the latest measurement data is stored in the time-series data storage unit 210 of the data transmission destination device 20 will be described. However, the present invention is not limited to this. The same can be applied to a calculation value, a control value, and the like, which are the results of calculation based on the measurement data at the timing of collecting the measurement data.

<Hardware configuration>
Next, a hardware configuration of the data transmission source device 10 according to the present embodiment will be described with reference to FIG. FIG. 2 is a diagram illustrating an example of a hardware configuration of the data transmission source device 10 according to the present embodiment.

  As shown in FIG. 2, the data processing device 10 according to the present embodiment includes a CPU 601, a RAM (Random Access Memory) 602, a flash ROM (Read Only Memory) 603, an external I / F 604, and a communication I / F 605. And These pieces of hardware are communicably connected to each other by a bus 607. The external I / F 604 is an interface with an external device. The external device includes a recording medium 604a and the like. The data processing device 10 can read and write the recording medium 604a via the external I / F 604.

  Examples of the recording medium 604a include a flexible disk, a CD (Compact Disc), a DVD (Digital Versatile Disk), an SD memory card (Secure Digital memory card), and a USB (Universal Serial Bus) memory card.

  The CPU 601 is an arithmetic unit that reads out programs and data from the flash ROM 603 onto the RAM 602 and executes processing to realize control and functions of the entire data transmission source device 10.

The flash ROM 603 is a nonvolatile semiconductor memory that can retain programs and data even when the power is turned off. The flash ROM 603 stores, for example, a program that implements the time-series data storage unit 110 and the latest data provision processing unit 100.
The RAM 602 is a volatile semiconductor memory that temporarily stores programs and data.

  The communication I / F 605 is an interface for connecting the data transmission source device 10 to the network N. The data transmission source device 10 transmits, to the data transmission source device 20, the latest data obtained by encrypting the latest data using the encryption method with authentication (that is, the encrypted latest data and the authentication tag) via the communication I / F 605. be able to.

  Further, it has a communication interface for collecting various measurement data from sensors and the like regularly or when necessary, and a program for storing the collected measurement data in the time-series data storage unit 110 (not shown). Further, as a nonvolatile memory storing programs and data, for example, an HDD (Hard Disk Drive) may be provided. The programs and data include a program for realizing the latest data provision processing unit 100, a time series data storage unit for accumulating measurement data in time series, and the like.

    The data transmission source device 10 according to the present embodiment has the hardware configuration illustrated in FIG. 2, so that various processes described below can be realized.

  Next, a hardware configuration of the data transmission destination device 20 according to the present embodiment will be described with reference to FIG. FIG. 3 is a diagram illustrating an example of a hardware configuration of the data transmission destination device 20 according to the present embodiment.

  As shown in FIG. 3, the data transmission destination device 20 according to the present embodiment includes an external I / F 701, a RAM 702, a CPU 703, a flash ROM 704, and a communication I / F 705. These pieces of hardware are communicably connected to each other by a bus 706.

  The external I / F 701 is an interface with an external device. The external device includes a recording medium 701a and the like. The data transmission destination device 20 can read and write the recording medium 701a via the external I / F 701. Examples of the recording medium 701a include an SD memory card and a USB memory card.

  The RAM 702 is a volatile semiconductor memory that temporarily stores programs and data. The CPU 703 is an arithmetic unit that reads out programs and data from the flash ROM 704 onto the RAM 702 and executes processing to realize control and functions of the entire data transmission source device 20.

  The flash ROM 704 is a nonvolatile semiconductor memory that can retain programs and data even when the power is turned off. The flash ROM 704 stores, for example, a program that implements the time-series data storage unit 210 and the latest data storage processing unit 200.

  The communication I / F 705 is an interface for connecting the data transmission destination device 20 to the network N. The data transmission destination device 20 can receive the latest encrypted data and the authentication tag from the data transmission source device 10 via the communication I / F 705. Further, as a nonvolatile memory storing programs and data, for example, an HDD (Hard Disk Drive) may be provided. The programs and data include a program for realizing the latest data storage processing unit 200, a time series data storage unit for accumulating measurement data in time series, and the like.

  The data transmission destination device 20 according to the present embodiment has the hardware configuration illustrated in FIG. 3, so that various processes described below can be realized.

<Functional configuration>
Next, a functional configuration of the data processing system 1 according to the present embodiment will be described with reference to FIG. FIG. 4 is a diagram illustrating an example of a functional configuration of the data processing system 1 according to the present embodiment.

  As shown in FIG. 4, the latest data providing unit 100 of the data transmission source device 10 according to the present embodiment includes a key generation unit 102, an encryption unit 104, and a communication unit 105. Note that the latest data providing unit 100 is realized by a process of causing the CPU 606 to execute one or more programs installed in the data transmission source device 10.

    The key generation unit 102 extracts the previous data 113 and the data 114 before and after the previous data 113 from the past data for the latest data to be encrypted stored in the time-series data storage unit 110, and extracts the previous data 113 and the previous data 113 using a predetermined algorithm. An encryption key 420 is created from the data 114 two times before.

  The encrypting unit 104 encrypts the latest data 112 by using an encryption method with authentication using the encryption key 420 created by the key generating unit 102, and creates the encrypted latest data 440 and the authentication tag 450. .

  Examples of the method of the encryption with authentication include EtM (Encrypt-then-MAC) and E & M (Encrypt-and-MAC).

  In EtM, the encryption unit 104 encrypts the latest data 112 using the encryption key 420 to create the encrypted latest data 440. Then, the encryption unit 104 calculates the hash value of the latest encrypted data 440 using the predetermined hash function and the encryption key 420, and sets the calculated hash value as the authentication tag 450.

  In E & M, the encryption unit 104 encrypts the latest data 112 using the encryption key 420 to create encrypted latest data 440. Then, the encryption unit 104 calculates the hash value of the latest data 112 using the predetermined hash function and the encryption key 420, and sets the calculated hash value as the authentication tag 450.

  Note that the encryption unit 104 may use MtE (MAC-then-Encrypt) as a technique of encryption with authentication. However, in this case, the encryption unit 104 couples the latest data 112 and the authentication tag created from the latest data 112 and encrypts them to create encrypted latest data 440.

  The communication unit 105 transmits the encrypted latest data 440 created by the encryption unit 104 and the authentication tag 450 to the data transmission destination device 20.

  As shown in FIG. 4, the latest data storage processing unit 200 of the data transmission destination device 20 according to the present embodiment includes a communication unit 201, a key generation unit 202, a decryption unit 203, a notification unit 204, and a determination unit 205. And a storage unit 207. Note that the latest data storage processing unit 200 is realized by a process of causing the CPU 703 to execute one or more programs installed in the data transmission destination device 20.

  The communication unit 201 receives the encrypted latest data 440 and the authentication tag 450 from the data transmission destination device 10.

  The key generation unit 202 extracts the previous data 113 and the data 114 two times before the previous data from the past data corresponding to the latest encrypted data stored in the time-series data storage unit 210, and extracts the key generation unit 102 of the data transmission source device 10. Using the same algorithm as that described above, the decryption key 460 is obtained from the previous data 113 and the data before last data 114 (that is, the previous data 114 and the data before last data 113 stored in the flash ROM 704 of the data transmission destination device 20) of the data transmission destination device 20. Create

  The decryption unit 203 decrypts the latest encrypted data 440 received by the communication unit 201 and creates the latest data 470 by using an authentication-based encryption method using the decryption key 460 created by the key generation unit 202. .

  The determination unit 205 verifies the authentication tag 450 received by the communication unit 201. That is, for example, the determination unit 205 generates an authentication tag from the latest data 470 decrypted by the decryption unit 203, and verifies the authentication tag 450 based on whether the created authentication tag matches the authentication tag 450. Determine whether the result is valid or unjust.

  Note that the decryption unit 203 and the determination unit 205 perform decryption of the latest encrypted data 440 and verification of the authentication tag 450 by using the same encryption method with authentication as the encryption unit 104 of the data transmission source device 10. . Further, the decoding unit 203 may include the processing of the determination unit 205.

  If the verification result of the authentication tag 450 by the determination unit 205 is invalid (that is, the authentication tag created by the determination unit 205 does not match the authentication tag 450 received by the communication unit 201), the notification unit 204 updates the latest data. Notify that the data could not be stored in the sequence data storage unit (storage failure).

  The storage unit 207 stores the time-series data when the verification result of the authentication tag 450 by the determination unit 205 is valid (that is, the authentication tag created by the determination unit 205 matches the authentication tag 450 received by the communication unit 201). The decrypted latest data 470 is stored in the section. Thus, the latest data 112 stored in the time-series data storage unit of the data transmission source device 10 and the latest data 470 stored in the time-series data storage unit of the data transmission destination device 20 become the same data.

<Details of processing>
Next, details of processing of the data processing system 1 according to the present embodiment will be described.

<<< Process from Data Acquisition to Transmission in Data Processing Device 10 >>>
Hereinafter, processing from the acquisition of past data in the data transmission source device 10 to the transmission to the data transmission destination device 20 will be described with reference to FIG. FIG. 5 is a flowchart illustrating an example of a process from acquisition of past data (previous data 113, data before last data 114) to transmission in the data transmission destination device 10 according to the present embodiment. The process illustrated in FIG. 5 is executed at the timing when the data transmission source device 10 collects the latest measurement data from a sensor or the like and the latest data 112 is stored in the time-series data storage unit 110.

  First, the key generation unit 102 acquires past data (previous data 113, data before last data 114) for the latest data 112 from the time-series data storage unit 110 (step S501). The data stored in the time-series data storage unit is measurement data collected from a sensor or the like. An identification code is attached to each measurement data corresponding to the input source of the sensor, etc., and is stored in chronological order at the measurement data collection timing from the sensor, etc. It is easy to acquire the data 113 and the data 114) two times before.

  Next, the key generation unit 102 generates an encryption key 420 from past data (previous data 113, data before last data 114) using a predetermined algorithm (step S502). For example, the key generation unit 102 creates the encryption key 420 as an output of the algorithm by connecting past data (previous data 113 and data 114 before the previous one) and inputting one binary data to the algorithm. Note that a predetermined hash function or the like can be used as the predetermined algorithm, for example. Further, the key generation unit 102 may use the concatenated binary data itself as the encryption key 420.

  Next, the encryption unit 104 encrypts the latest data 112 by an authentication-based encryption method using the encryption key 420 created in step S502 described above, and generates the encrypted latest data 440 and the authentication tag 450. Is created (step S503).

  Next, the communication unit 105 transmits the encrypted latest data 440 and the authentication tag 450 created in step S503 to the data transmission destination device 20 (step S504).

  As described above, in the data processing system 1 according to the present embodiment, the latest encrypted data 440 and the authentication tag 450 created by the data transmission source device 10 are transmitted to the data transmission destination device 20.

<<< Process in which Data Source Apparatus Creates Encryption Key [1] >>>
In S502 of FIG. 5 described above, it has been described that the key generation unit 102 generates the encryption key 420 from the past data (the previous data 113 and the data before the previous one 114) using a predetermined algorithm.

  Hereinafter, the process of creating an encryption key will be described in more detail with reference to FIGS. FIG. 7 is a flowchart illustrating an example of a process in which the data transmission source device 10 according to the present embodiment creates an encryption key.

  First, the key generation unit 102 searches the time-series data storage unit 110 for the existence of the previous data 113 or the data 114 before last time (step 701). If any of the past data exists in S701, it is next searched whether the previous data 113 and the data 114 before last exist (step 702). If both the previous data 113 and the data before last exist in S702 (step 702: YES), an encryption key 420 is created from the past data (previous data 113, data before last 114) (step 703). FIG. 4 is a diagram illustrating an example of a functional configuration of the data processing system 1 according to the present embodiment when both the previous data 113 and the data before last 114 exist.

  Returning to S702, if there is no data 114 two times before (step 702: NO), an encryption key is created based on past data (previous data) (step 704). FIG. 9 is a diagram illustrating an example of a functional configuration of the data processing system 1 according to the present embodiment when there is no data two times before.

  Further, returning to S701, if neither the previous data 113 nor the data two times before exists (step 701 NO), an encryption key is created based on the device ID of the own device held by the data transmission source device 10 (step 705). FIG. 10 is a diagram illustrating an example of the functional configuration of the data processing system 1 according to the present embodiment when neither the previous data 113 nor the data 114 before the last exists.

<<<< Process in which data transmission source device creates encryption key [2] >>
In the above <<<< Process in which data transmission source device creates encryption key [1] >>>>, the process of creating the encryption key has been described with reference to the flowchart in FIG. Here, other processes for creating the second encryption key will be described. The main characteristic part in comparison with [Part 1] corresponds to S501 in FIG.

  First, the key generation unit 102 acquires a predetermined number of pieces of past data from the past data stored in the time-series data storage unit 110 for the latest data to be encrypted, using the first random calculation unit. An encryption key used for encryption is created based on the acquired past data. The first random calculation unit specifies a storage location of past data by using a predetermined number of random functions, and acquires the corresponding past data. Since the past data is stored in the time-series data storage unit 110 in time series, it is easy to specify the past data. The same applies to the key generation unit 202. If there is no past data or there is no past data, the same processing as [Part 1] may be performed.

<<< Process in which Data Source Device Creates Encryption Key [Part 3] >>>>
Here, other processes for creating the third encryption key will be described. The main characteristic part in comparison with [Part 1] corresponds to S501 in FIG.

  First, the key generation unit 102 retrieves a predetermined number of past data from the series in which the latest data is stored, from the past data stored in the time-series data storage unit 110 for the latest data to be encrypted. An encryption key to be used for encryption is created based on the acquired past data. Since the past data is stored in the time-series data storage unit 110 in time series, it is easy to specify the past data. The same applies to the key generation unit 202. If there is no past data or there is no past data, the same processing as [Part 1] may be performed.

<<< Process in which Data Source Apparatus Creates Encryption Key [Part 4] >>>>
Here, other processes for creating the fourth encryption key will be described.

  First, when encrypting a plurality of latest data having different identification codes and transmitting the latest data collectively at one time, the key generation unit 102 uses the second random calculation unit to select one of the latest data from among the plurality of latest data. Only one encryption key is created, and only one encryption key commonly used for encrypting a plurality of latest data to be transmitted at one time in a lump based on the selected latest data is created. The method of acquiring past data for the selected latest data may be any one of [Part 1] to [Part 3] described above or a combination thereof.

<<<< Process in which data transmission source device creates encryption key [5] >>
Here, other processes for creating a fifth encryption key will be described.

  First, when encrypting a plurality of latest data having different identification codes and transmitting them collectively at one time, the key generation unit 102 uses an encryption key used for encryption based on the past data for each of the plurality of latest data. Is created respectively. The method of acquiring past data for each of the latest data may be any one of the above [Part 1] to [Part 3] or a combination thereof.

<< Process in which Data Destination Device 20 Stores Latest Data in Time-Series Data Storage Unit >>
Hereinafter, a process in which the data transmission destination device 20 stores the latest data 470 in the time-series data storage unit 210 will be described with reference to FIG. FIG. 6 is a flowchart illustrating an example of a process in which the data transmission destination device 20 according to the present embodiment stores the latest data 112 in the time-series data storage unit 210.

  First, the communication unit 201 receives the encrypted latest data 440 and the authentication tag 450 from the data transmission source device 10 (step S601).

  Next, the key generation unit 202 uses the same algorithm as the key generation unit 102 of the data transmission source device 10 to derive the decryption key 460 from the past data (the previous data 113 and the data before last data 114) of the data transmission destination device 20. It is created (step S602).

  Next, the decryption unit 203 decrypts the latest encrypted data 440 received in step S601 by using an authentication-assisted encryption method using the decryption key 460 created in step S602 described above. 470 is created (step S603).

  Next, the determination unit 205 verifies the authentication tag 450 received in step S601 (step S604). That is, for example, the determination unit 205 creates an authentication tag from the latest data 470 created in step S603, and determines whether the created authentication tag matches the authentication tag 450. It is determined whether the verification result is valid or invalid.

  If it is determined in step S604 that the verification result is valid, the storage unit 207 stores the latest data 470 created in step S603 in the time-series data storage unit (step S605).

  The time-series data storage unit 210 in which the latest data 470 is stored is the same data as the data stored in the time-series data storage unit 110 of the data transmission source device 10.

On the other hand, if it is determined in step S604 that the verification result is invalid (not valid), the notification unit 204 notifies that the latest data could not be stored in the time-series data storage unit (storage failure) (step S604). S606). The notification unit 204 may notify the storage failure of the latest data 470 by, for example, turning on an LED (Light Emitting Diode) lamp or emitting a buzzer sound. Further, the notification unit 204 may notify the storage failure of the latest data by transmitting a mail indicating the storage failure to a predetermined mail address.
<<< Process in which Data Destination Apparatus Creates Decryption Key >>
In S602 of FIG. 6 described above, it has been described that the key generation unit 202 generates the decryption key 460 from the past data (the previous data 113 and the data before the previous one 114) using a predetermined algorithm.

  Hereinafter, the process of creating the decryption key will be described in more detail with reference to FIGS. FIG. 8 is a flowchart illustrating an example of a process in which the data transmission destination device 20 according to the present embodiment creates a decryption key.

  First, the key generation unit 202 searches the time-series data storage unit 210 for the existence of the previous data 113 or the data 114 before last time (step 801). If any of the past data exists in S801, it is next searched whether the previous data 113 and the data 114 before last exist (step 802). If both the previous data 113 and the data before the previous data exist in S802 (step 802: YES), a decryption key 460 is created from the past data (the previous data 113 and the data before the previous data 114) (step 803). FIG. 4 is a diagram illustrating an example of a functional configuration of the data processing system 1 according to the present embodiment when both the previous data 113 and the data before last 114 exist.

  Returning to S802, if there is no data 114 two times before (step 802 NO), a decryption key is created based on the past data (previous data) (step 804). FIG. 9 is a diagram illustrating an example of a functional configuration of the data processing system 1 according to the present embodiment when there is no data two times before.

  Further, returning to S801, if neither the previous data 113 nor the data 114 before last exists (step 801 NO), an encryption key is created based on the device ID of the own device held by the data transmission source device 10 (step 705). FIG. 10 is a diagram illustrating an example of the functional configuration of the data processing system 1 according to the present embodiment when neither the previous data 113 nor the data 114 before the last exists. FIG. 11 is a diagram illustrating an example of a configuration of a device ID table in the data transmission destination device according to the present embodiment. In the device ID table 300 shown in FIG. 11, information on a data transmission source device is set in advance and stored in a memory area. The device ID table 300 includes device ID information, which is a device unique ID of the data transmission source device 10, and the device name and IP address of the data transmission source device as packet information corresponding to the device ID. The data transmission destination device 20 refers to the header information of the communication packet transmitted from the data transmission source device, obtains the device name or the IP address of the transmission source device containing the header information, and checks the packet against the packet information in the device table 300. Then, the device ID of the transmission source can be acquired from the device table.

In this way, even if a third party can obtain information on a communication packet flowing on the network, the information on the basis of the encryption key and the decryption key cannot be obtained. Can not. Therefore, when neither the previous data 113 nor the data 114 before last exists (NO in step 801), security is maintained even if an encryption key is created based on the device ID of the own device held by the data transmission source device 10.
<Supplementary explanation Communication packet configuration>
Next, a functional configuration of a communication packet in the data transmission source device according to the present embodiment will be described with reference to FIG. FIG. 12 is a diagram illustrating an example of a functional configuration of a communication packet in the data transmission source device according to the present embodiment.

  As shown in FIG. 12, communication packets used for transmission by the data source device 10 according to the present embodiment are classified into a header portion and a data portion, and the header portion includes a destination address or a destination device name, a source An address or a source device name, a message type, a message ID, a data size, and the like are assigned, and data is assigned to the data portion. When the data transmission source device transmits the encrypted latest data 440 and the authentication tag 450 to the data transmission destination device, the communication unit 105 includes, in the header part, the transmission destination address or the transmission destination device name of the data transmission destination device, and the data transmission source. The source address or the source device name of the device, a message type for notifying measurement data, a message ID such as an identification code corresponding to the measurement data, a data size, and the like are input, and the latest encrypted data 440 to be transmitted to the data portion is input. The authentication tag 450 is input as a set, and a communication packet is created and transmitted.

When sending a plurality of latest data, a plurality of identification codes may be set in the message ID, and a plurality of data in which the encrypted latest data and the authentication tag are set may be input to the data section. Also, when one encryption key is created for a plurality of data, data obtained by setting one authentication tag to a plurality of authenticated latest data may be input to the data section.
<Summary>
As described above, in the data processing system 1 according to the present embodiment, the data transmission destination device 20 stores the latest data in time-series data based on the encrypted latest data 440 and the authentication tag 450 received from the data transmission source device 10. It can be stored in the unit 210. As a result, in the data processing system 1 according to the present embodiment, for example, a situation in which incorrect latest data is written to the data transmission destination device 20 (that is, when the incorrect latest data is stored in the time-series data storage unit). Situation).

  Further, in the data processing system 1 according to the present embodiment, the encryption key 420 is created based on the past data 111 included in the data transmission source device 10 and decrypted based on the past data 111 included in the data transmission destination device 20. A key 460 is created. Therefore, in the data processing system 1 according to the present embodiment, the data transmission source device 10 and the data transmission destination device 20 do not need to manage the encryption key 420 and the decryption key 460, respectively (that is, the flash ROM 603, It is not necessary to store the encryption key 420 and the decryption key 460 in the 704 respectively.) Therefore, in the data processing system 1 according to the present embodiment, leakage of the encryption key 420 and the decryption key 460 can be prevented.

  Furthermore, in the data processing system 1 according to the present embodiment, since the encryption key 420 and the decryption key 460 are created based on the past data, every time the latest data is stored in the time-series data storage units 110 and 210, The encryption key 420 and the decryption key 460 can also be updated. Therefore, in the data processing system 1 according to the present embodiment, even if the encryption key 420 or the decryption key 460 is leaked, the key is updated by updating the past data, and thereafter, the unauthorized latest data is updated. It is possible to prevent a situation in which the data is written to the data transmission destination device 20. After the latest data is stored, it is desirable to immediately delete the information of the encryption key 420 and the decryption key 460 so that the information is not stored in the data processing system 1.

    Note that the present invention is not limited to the above-described embodiments specifically disclosed, and various modifications and changes can be made without departing from the scope of the claims.

Reference Signs List 1 data processing system 10 data transmission device 20 data transmission destination device 100 latest data provision processing unit 102 key generation unit 104 encryption unit 105 communication unit 111 past data 112 latest data 113 previous data 114 previous data 115 device ID
116 Device ID table packet header information 200 Latest data storage processing unit 201 Communication unit 202 Key generation unit 203 Decryption unit 204 Notification unit 205 Judgment unit 207 Storage unit 300 Device ID table 420 Encryption key 440 Encrypted latest data 450 Authentication Tag 460 Decryption key 470 Latest data

Claims (14)

A data transmission source device connected to a data transmission destination device having past data and transmitting the latest encrypted data to the data transmission destination device by encrypting the latest data,
A time-series data storage unit for storing data to be transmitted in a time-series,
An encryption key generation unit that creates an encryption key used for encryption based on the past data stored in the time-series data storage unit and transmitted in the past,
Using the encryption key created by the encryption key generation unit, an encryption unit that creates the encrypted latest data,
A transmitting unit that transmits the encrypted latest data created by the encrypting unit to the data transmission destination device;
A data transmission device having: The encryption unit includes:
In addition, create an authentication tag to verify the integrity after encryption,
The transmission unit,
The data transmission source device according to claim 1, further comprising transmitting the authentication tag to the data transmission destination device. The encryption key generator,
Of the past data stored in the time-series data storage unit with respect to the latest data to be encrypted, a predetermined number of past data are obtained using a first random calculation unit, and used for encryption based on the past data. 3. The data transmission source device according to claim 1, wherein the encryption key is created. The encryption key creation unit,
Among the past data stored in the time-series data storage unit for the latest data to be encrypted, the past data is obtained by the predetermined number from the series in which the latest data is stored, and the past data is acquired by the predetermined number. 3. The data transmission source device according to claim 1, wherein the encryption key used for encryption is created based on data. The encryption key creation unit,
5. The data transmission source device according to claim 3, wherein when the predetermined number of pieces of past data cannot be obtained, the encryption key used for encryption is created based on the obtained past data. 6. The encryption key generator,
In the case where a plurality of latest data having different identification codes are encrypted and transmitted collectively at one time, only one of the plurality of latest data is selected by using a second random calculation unit, and the selected latest data is selected. Creating only one encryption key that is commonly used for encrypting a plurality of latest data to be transmitted at one time based on the past data with respect to the latest data;
The data transmission source device according to claim 1. The encryption key generator,
When encrypting a plurality of latest data having different identification codes and transmitting them collectively at once, creating the encryption keys used for encryption based on the past data for each of the plurality of latest data.
The data transmission source device according to claim 1. In a data transmission destination device connected to a data transmission source device having past data and the latest data,
A receiving unit that receives the encrypted latest data obtained by encrypting the latest data from the data transmission source device,
A time-series data storage unit that accumulates the latest data received in the past in time series as the past data,
A decryption key generation unit that creates a decryption key used for decrypting the encrypted latest data based on the past data stored in the time-series data storage unit,
Using the decryption key, a decryption unit that decrypts the encrypted latest data to create the latest data,
A storage unit that stores the latest data created by the decoding unit as the past data in the time-series data storage unit,
A data transmission destination device having: The receiving unit,
Further, receiving a first authentication tag for verifying the integrity of the encrypted latest data from the data transmission source device,
The decoding unit,
Further, a second authentication tag is created from the decrypted latest data, and the integrity of the encrypted latest data is verified using the second authentication tag and the first authentication tag. Item 9. A data transmission destination device according to Item 8. The decryption key generator,
The data transmission source device is identified from the device ID mapping information based on the header information of the packet transmitted from the data transmission source device, and the past data for the latest encrypted data is transmitted from the time-series data storage unit based on the header information. To create a decryption key to be used for decryption based on the acquired past data,
The data transmission destination device according to claim 8. The decoding unit,
After the receiving unit receives the encrypted latest data, creates the decryption key,
The decryption key generator,
When the storage unit stores the latest data, deletes the decryption key;
The data transmission destination device according to claim 8. A data processing system in which a data transmission source device having latest data and past data and a data transmission destination device having past data are connected,
The data source device is
A time-series data storage unit for storing data to be transmitted in a time-series,
An encryption key generation unit that creates an encryption key used for encryption based on the past data stored in the time-series data storage unit and transmitted in the past,
Using the encryption key created by the encryption key generation unit, an encryption unit that creates the latest encrypted data by encrypting the latest data,
A transmitting unit that transmits the encrypted latest data created by the encrypting unit to the data transmission destination device;
Has,
The data destination device is
A receiving unit that receives the encrypted latest data from the data transmission device,
A time-series data storage unit that accumulates the latest data received in the past in time series as the past data,
A decryption key generation unit that creates a decryption key used for decryption based on the past data stored in the time-series data storage unit,
Using the decryption key created by the decryption key generation unit, a decryption unit that decrypts the encrypted latest data to create the latest data,
A storage unit that stores the latest data created by the decoding unit as the past data in the time-series data storage unit,
A data processing system having: A data processing method used for a data transmission source device connected to a data transmission destination device having past data and transmitting the latest encrypted data to the data transmission destination device by encrypting the latest data,
A time-series data storage unit for storing data to be transmitted in a time-series,
An encryption key generation procedure for creating an encryption key used for authenticated encryption based on the past data stored in the time-series data storage unit and transmitted in the past,
Using the encryption key created by the encryption key generation procedure, verify the integrity of the latest encrypted data obtained by encrypting the latest data using the authenticated encryption method and the latest encrypted data. An encryption step to create an authentication tag for
A transmission step of transmitting the encrypted latest data created in the encryption step and the authentication tag to the data transmission destination device;
Having,
Data processing method. A data processing method used for a data transmission destination device connected to a data transmission source device having past data and latest data,
A receiving step of receiving, from the data transmission apparatus, the latest data in which the latest data has been encrypted by an authenticated encryption method and an authentication tag for verifying the integrity of the encrypted latest data;
A time-series data storage unit that accumulates the latest data received in the past in time series as the past data,
A decryption key generation procedure for acquiring the past data from the time-series data storage unit and creating a decryption key for use in decrypting the encrypted latest data based on the acquired past data,
A decryption key creation procedure for creating a decryption key used for authenticated encryption based on the past data for the latest encrypted data,
Using the decryption key created by the decryption key creation procedure and the authentication tag received by the reception procedure, decrypts the encrypted latest data by the authentication-assisted encryption method to create the latest data. And a decryption procedure for creating an authentication tag from the latest data;
A storage unit procedure for storing the latest data created by the decoding procedure as the past data in the time-series data storage unit,
Having,
Data processing method.