JP6308837B2 - Communication system, communication method, and communication program - Google Patents

Description

  The present invention relates to a communication system having a communication terminal and a center apparatus capable of communicating with the communication terminal, and a communication method and a communication program executed in the communication system.

  Conventionally, in facilities such as offices, stores, and homes, security systems that install various sensors and monitoring cameras to monitor the safety status of buildings have been used. In the security service using such a security system, these communication terminals have come to be used with the spread of communication terminals such as smartphones and tablet terminals in recent years.

  FIG. 7 is a diagram for explaining an example of a security service performed using the communication terminal 200 in the conventional security system 100. For example, as shown in FIG. 7 (a), a patrol security service for checking a patrol area that is predetermined in the security target facility or installed in a guard target facility as shown in FIG. 7 (b). The communication terminal 200 such as a smartphone is used for an abnormality handling security operation that performs an emergency countermeasure such as an inspection based on an abnormality signal from the security device 400. The communication terminal 200 is mainly used for the purpose of managing and supporting the work of guards and the security work, and is configured to be able to communicate with the center apparatus 300 installed in the monitoring center via the communication network 500.

  For example, the communication terminal 200 stores security-related information related to security for supporting the security service, and a security guard can display and check the security-related information on the screen of the communication terminal as necessary. Security-related information includes information such as the security schedule that indicates the type, time zone, and location of the security service performed by the security guard, a map that indicates the location of the security target facility, a sketch of the security target facility, and the locations and items that should be inspected. And provided from the center apparatus 300 to the communication terminal 200 via the communication network 500.

  In addition, the communication terminal 200 receives the security staff's work situation, inspection records and evidence images, and the input data is transmitted to the center device 300. For example, the work status is input data indicating the start / end of the work of the guard, the express / arrival at the facility to be guarded, and the like. The inspection record is input data such as the state of the inspection location, the content of the abnormality, and a memorandum that the security guard inputs to the communication terminal while inspecting each inspection item. Further, when an evidence image or the like is required, the security guard takes a picture with the camera of the communication terminal 200, and the image data acquired by the photography is also transmitted to the center apparatus 300 as input data.

  As described above, highly confidential information including business confidential matters such as work status, inspection records, and evidence images, and customer personal information is input to a communication terminal used for security work. Therefore, it is necessary to ensure high confidentiality of the input data stored in the communication terminal.

  Japanese Patent Application Laid-Open No. 2004-133830 proposes a technique for ensuring the confidentiality of image data by encrypting image data of a photographed image obtained by photographing using a pre-stored encryption key. In order to decrypt the encrypted image data, for example, the user is authenticated by inputting a decryption key encryption with respect to the encryption key used for encryption. It is not easy to decrypt and view or copy.

JP 2004-120301 A

  However, when a plurality of persons in charge use a communication terminal for taking over duties such as duty duties, the same communication terminal and the same encryption key may be reused between the plurality of persons in charge. In this case, for example, when a malicious third party obtains an encryption key for decryption by any method, the data input by all persons in charge using the communication terminal are encrypted and stored in the communication terminal. Even if stored, there is a problem in that there is a risk that the data will be decrypted and leaked with one encryption key. In particular, the persons in charge who use the communication terminal are often notified in advance of the key encryption for decryption so that the encrypted input data can be displayed or changed on the communication terminal. Therefore, in the unlikely event that one of the persons in charge becomes a malicious third party, there is a high risk that the input data entered by all security guards using the communication terminal will be leaked by entering the decryption key encryption. Therefore, it is necessary to take measures to prevent leakage of these data.

  In view of the above problems, an object of the present invention is to provide a communication terminal, a communication system, a communication method, and a communication program that can reliably prevent leakage of input data input to the communication terminal.

  According to one aspect of the present invention for solving this problem, a communication system is provided that includes a communication terminal having a terminal input unit and a center device capable of communicating with the communication terminal. In such a communication system, the center device communicates the generated public key with a center key generating unit that generates a pair of public key and secret key of the public key cryptosystem at the timing when the user starts using the communication terminal. A center communication unit that transmits to the terminal, and a center storage unit that stores the generated secret key. The communication terminal receives a common key of a common key cryptosystem and a terminal communication unit that receives a public key from the center device. The terminal key generation unit to be generated and the input data input from the terminal input unit are encrypted with a common key to be encrypted data, and the common key is encrypted with a public key to be an encryption key A terminal storage unit that stores a received public key, encrypted encrypted data, and an encryption key associated with the encrypted data.

  In such a communication system, the terminal key generation unit preferably generates a common key when data is input from the terminal input unit.

  Further, in such a communication system, the terminal key generation unit generates a first predetermined number of common keys, and among the generated first predetermined number of common keys, an unused common key that is not used by the encryption unit. When the number falls below a second predetermined number that is smaller than the first predetermined number, it is preferable to newly generate a common key to be the first predetermined number of common keys.

  Further, in such a communication system, the terminal input unit has a photographing unit that acquires image data as input data, and the encryption unit encrypts the image data input by the photographing unit using a common key. Is preferred.

  In such a communication system, it is preferable that input of image data by the photographing unit is prohibited when the public key is not stored in the terminal storage unit.

  Further, in such a communication system, the terminal communication unit transmits the encrypted data and the encryption key stored in the terminal storage unit to the center device, and the communication terminal transmits the encrypted data that the terminal communication unit has completed transmission and The encryption key is deleted from the terminal storage unit, the center communication unit receives the encrypted data and the encryption key from the communication terminal, and the center device uses the secret key stored in the center storage unit. It is preferable to further include a decryption unit that decrypts the encrypted data received using the decrypted common key.

  Further, in such a communication system, the terminal input unit inputs user authentication information of the user, and the center key generation unit uses the communication terminal when the center communication unit receives the user authentication information from the communication terminal. As a start timing, it is preferable to generate a pair of public key and secret key.

  Furthermore, in the communication system, it is preferable that the center device deletes the secret key from the center storage unit when the center communication unit receives a work end signal informing the end of work from the communication terminal.

  According to another aspect of the present invention, there is provided a method performed by a communication terminal having a terminal input unit and a center apparatus capable of communicating with the communication terminal. In this communication method, the center device generates a pair of public key and secret key of the public key cryptosystem at a timing when the center key generation unit starts using the communication terminal by the user, and the center communication unit Has a step of transmitting the generated public key to the communication terminal, and a center storage unit storing the generated secret key. The communication terminal receives the public key from the center device by the terminal communication unit. And a step in which the terminal key generation unit generates a common key for the common key encryption method, and an encryption unit encrypts the input data input from the terminal input unit using the common key to obtain encrypted data. Encrypting the common key with a public key to obtain an encryption key, and the terminal storage unit receiving the received public key, the encrypted encrypted data, and the encryption associated with the encrypted data Write With the method comprising the steps of, a.

  According to another aspect of the present invention, there is provided a communication program executed by a communication terminal having a terminal input unit and a center device capable of communicating with the communication terminal. Such a communication program includes a procedure for generating a pair of public key and secret key of a public key cryptosystem at a timing when a center key generation unit starts using a communication terminal by a user, and a center communication unit Executes a procedure for transmitting the generated public key to the communication terminal and a procedure for the center storage unit to store the generated secret key, and causes the terminal communication unit to receive the public key from the center device. The terminal key generation unit generates a common key for the common key encryption method, and the encryption unit encrypts the input data input from the terminal input unit using the common key to obtain encrypted data. A procedure in which the common key is encrypted using a public key to obtain an encryption key, and the terminal storage unit receives the received public key, the encrypted encrypted data, and the encryption associated with the encrypted data. A procedure for storing the activation key; To be executed.

  According to another aspect of the present invention, a communication terminal having a terminal input unit and capable of communicating with a center apparatus is provided. When the communication terminal is used, such a communication terminal is input from a terminal communication unit that receives a public key from the center device, a terminal key generation unit that generates a common key of a common key cryptosystem, and a terminal input unit. The input data is encrypted using a common key to obtain encrypted data, the common key is encrypted using a public key, and the encryption unit encrypts the encrypted key, the received public key, and the encrypted encryption A terminal storage unit that stores data and an encryption key associated with the encrypted data.

  In the communication terminal, the terminal key generation unit generates the common key for each input data input from the terminal input unit, and the encryption unit encrypts the input data using the common key. It is preferable to delete the key.

  According to the present invention, it is possible to provide a communication terminal, a communication system, a communication method, and a communication program that can reliably prevent leakage of input data input to the communication terminal.

It is a lineblock diagram showing an example of a security system concerning one embodiment of the present invention. It is a block diagram of the communication terminal which concerns on one Embodiment of this invention. It is a block diagram of the center apparatus which concerns on one Embodiment of this invention. It is a figure which shows an example of a structure of the work management information which concerns on one Embodiment of this invention. It is an operation | movement sequence diagram of the communication terminal and center apparatus which concern on one Embodiment of this invention. It is an operation | movement sequence diagram of the communication terminal and center apparatus which concern on one Embodiment of this invention. It is a figure explaining the example of the security service performed using a communication terminal in the conventional security system.

  Hereinafter, a security system as one embodiment of a communication system of the present invention will be described with reference to the drawings.

  In the security system to which the present invention is applied, the user starts using the communication terminal so that the encryption key used for encrypting the input data of the communication terminal is changed every time the user of the communication terminal changes. Generated when In addition, the inventor of the present invention is able to encrypt large input data such as an image in a communication terminal with an encryption method with a small processing load such as a common key encryption method. We obtained the knowledge that it would take time if it was performed with a heavily loaded cryptosystem. Based on this knowledge, the communication terminal according to the present invention encrypts input data with a common key encryption method using a common key, and encrypts the common key used for the encryption with a public key encryption method using a public key. We will make it. In the embodiment described below, a public / private key pair used in public key cryptography is generated at the timing when the user starts using the communication terminal. Here, when the center apparatus receives a work start signal indicating the start of work of the user from the communication terminal, an example of generating a key pair of the public key cryptosystem as a timing at which the user starts using the communication terminal Is described.

  FIG. 1 is a configuration diagram illustrating an example of a security system 1 according to an embodiment of the present invention. As shown in FIG. 1, such a security system 1 includes a communication terminal 2 used for security work, a center device 3 that monitors and manages the security system 1, a suspicious person's intrusion or fire in a security target facility, and the like. There are a security device 4 connected to various sensors (not shown) for detecting abnormalities in the communication, and a communication network 5 connecting them.

  The communication terminal 2 is a portable information processing device such as a smartphone, a tablet PC, or a notebook PC used for security work. For example, the communication terminal 2 transmits a work start signal and a work end signal indicating the start and end of work of the security guard to the center device 3 via the communication network 5. In addition, the communication terminal 2 receives input data together with security-related information such as a map of a security target facility, a sketch, a security schedule, inspection points, and inspection items from the center device 3 that has received the work start signal via the communication network 5. A public key used for encrypting the common key to be encrypted can be received. Further, the communication terminal 2 encrypts the input data such as the evidence image photographed by the communication terminal 2 and the input inspection record with the common key, and the center through the communication network 5 together with the common key encrypted with the public key. It can be transmitted to the device 3.

  The center device 3 is provided in a monitoring center for monitoring the security device 4 installed in the facility to be guarded, a security headquarters for dispatching guards, a command headquarters for remotely issuing instructions to the guards, and a disaster prevention center in a large building It will be installed in facilities that manage security, such as the disaster prevention headquarters. When the center device 3 receives the abnormality detection signal from the security device 4 through the communication network 5, the center device 3 notifies the security target facility where the security device 4 that has transmitted the abnormality detection signal is installed and the content of the detected abnormality to the notification unit. And notify the monitor through the display. The monitor of the center device 3 notified of the abnormality contacts the communication terminal 2 carried by the guard, and goes to the property where the guard device 4 in which the abnormality has occurred is inspected by the guard. Instruct to take corrective action. In addition, the center device 3 manages work of guards using the communication terminal 2, provides security-related information and public keys to the communication terminals 2, and inspection records and evidence input to each communication terminal 2 during security. Collect and centrally manage input data such as images.

  The security device 4 is installed in each security target facility as a monitoring target for monitoring the safety situation, such as a house, an apartment dwelling unit, or a business office, and one or a plurality of sensors (not shown) for detecting an abnormality of each facility. Connected). The sensor is, for example, a heat sensor or smoke sensor for detecting a fire, a magnet sensor that is attached to an opening / closing part such as a window or a door, and detects the opening / closing thereof, or a detection range based on a change in the amount of received infrared light. An infrared sensor that detects the presence or absence of an intruder or the like. Alternatively, the sensor may be an image sensor that detects the presence or absence of an intruder or the like in the imaging range based on a difference signal between the captured image and a normal image stored in advance. When an abnormality is detected by the sensor, the security device 4 transmits an abnormality detection signal indicating that the abnormality has been detected and a signal indicating the identification number of the security device 4 to the center device 3 via the communication network 5.

  The communication network 5 connects the communication terminal 2 and the center device 3 and the center device 3 and the security device 4 in a communicable manner. The communication network 5 may have any form as long as communication is possible between them, and may be a single communication system network or a plurality of communication system networks connected via a gateway server (not shown). It may be configured. Further, the communication terminal 2 and the center device 3 and the center device 3 and the security device 4 may be simultaneously connected by a plurality of forms of communication networks.

  In the example shown in FIG. 1, the communication network 5 includes an IP network 51 such as the Internet, and W-CDMA, CDMA2000, LTE (Long Term Evolution) connected to the IP network 51 via a gateway server (not shown). And a mobile phone network 54 in accordance with a communication method such as WiMAX or PHS. The IP network 51 and the cellular phone network 54 include an access point (AP) 53 and base stations (BS) 55 to 57, and communication terminals are provided via at least one of the access point 53 and the base stations 55 to 57. 2 and wireless communication. In the following, the communication terminal 2 is connected to the mobile phone network 54 via the base station 55, and the center device 3 via the IP network 51 connected from the mobile phone network 54 to a gateway server (not shown). A case where communication is performed will be described.

  FIG. 2 is a configuration diagram of the communication terminal 2 according to an embodiment of the present invention. As illustrated in FIG. 2, the communication terminal 2 includes a terminal operation unit 21, a photographing unit 22, a terminal display unit 23, a terminal communication unit 24, a terminal storage unit 25, and a terminal control unit 26.

  The terminal operation unit 21 is an operation interface for a user of the communication terminal 2 to input information to the communication terminal 2 and includes an input device such as a button, a numeric keypad, and / or a touch panel. In addition, the terminal operation unit 21 may include a microphone that performs voice input. If there is an input operation from the user, the terminal operation unit 21 outputs a signal corresponding to the input operation to the terminal control unit 26. The user can input information such as instructions for processing to be performed by the communication terminal 2, start and end of work, and inspection records by an input operation to the terminal operation unit 21.

  The imaging unit 22 may be a known built-in camera or an external camera that includes an imaging element such as a CCD element or a C-MOS element, an optical system component, an A / D converter, an encoder, and the like. The image data acquired by the image capturing unit 22 may be either a still image or a moving image. For this reason, the image capturing unit 22 is an image in a format that can be processed by both the communication terminal 2 and the center device 3 such as JPEG or MPEG. It is preferable that data can be acquired.

  In the present embodiment, the terminal input unit includes a terminal operation unit 21 and a photographing unit 22. The input data includes inspection records and image data input from the terminal operation unit 21 and the imaging unit 22.

  The terminal display unit 23 includes a display device such as a liquid crystal display or a touch panel display. The terminal display unit 23 displays security-related information such as a security schedule, a security target map, a floor plan, and an inspection record input screen that can be input while checking the inspection location and inspection items to be inspected. In addition, the terminal display part 23 may be integrated with a part of the terminal operation part 21 by comprising a touch panel display.

  The terminal communication unit 24 includes a communication interface circuit for allowing the communication terminal 2 to perform wireless communication of a mobile phone with the base station 55 through an antenna according to a communication method such as W-CDMA, CDMA2000, or LTE. The terminal communication unit 24 sends information received from the center apparatus 3 via the base station 55 to the terminal control unit 26. Further, the terminal communication unit 24 transmits the information received from the terminal control unit 26 to the center device 3 via the base station 55. Note that the terminal communication unit 24 may include a communication interface circuit according to another communication method such as a wireless LAN, WiMAX, or PHS, or may include a plurality of communication interface circuits so as to correspond to a plurality of communication methods. May be.

  The terminal communication unit 24 sends a work start signal and a work end signal indicating the start and end of the user's work to the center device 3 via the communication network 5. Further, the terminal communication unit 24 receives the security related information and the public key sent from the center device 3 in response to the work start signal. In addition, the terminal communication unit 24 sends the encrypted input data and the common key to the center device 3 via the communication network 5.

  The terminal storage unit 25 includes a semiconductor memory such as a ROM (Read Only Memory), a RAM (Random Access Memory), and / or an EPROM (Erasable Programmable Read Only Memory). The terminal storage unit 25 stores a computer program and various data for controlling the communication terminal 2, and exchanges such information with the terminal control unit 26. The terminal storage unit 25 may include an auxiliary memory such as a micro SD card as necessary. The computer program and / or data may be provided from the communication network 5 or the like via the terminal communication unit 24 and stored in the terminal storage unit 25, or stored and provided as a firmware in a semiconductor memory such as ROM or EPROM. Also good.

  As illustrated in FIG. 2, the terminal storage unit 25 stores security related information, a public key, a common key, encrypted data, and an encryption key.

  The security-related information includes, for example, a security schedule indicating the type, time zone, and location of the security service performed by the user of the communication terminal 2, a map indicating the location of the security target facility, and the arrangement of the monitoring target such as a safe. It has information that supports security, such as a sketch drawing, an inspection record input form having inspection points and inspection items to be inspected. The security-related information stored in the terminal storage unit 25 is sent from the center device 3 in response to a work start signal indicating the start of work of the user being sent from the terminal communication unit 24 to the center device 3. Further, it is security related information corresponding to the personal identification information of the user that the work start signal has. The security related information sent from the center device 3 is received by the terminal communication unit 24 and stored in the terminal storage unit 25.

  The public key is an encryption key used by the encryption unit 262 to encrypt the common key stored in the terminal storage unit 25 using the public key encryption method. The public key is generated by the center apparatus 3 that has received a work start signal indicating the start of work of the user from the communication terminal 2 and is sent to the communication terminal 2. The public key thus sent from the center device 3 is received by the terminal communication unit 24 and stored in the terminal storage unit 25. It is necessary to prove that the public key sent to the communication terminal 2 is generated by the center device 3, that is, not sent by a malicious third party. Therefore, it is preferable to transmit the public key via a secure network such as an in-house LAN where security is protected, or to ensure safety using a public key certificate by a certificate authority.

  The common key is an encryption key used by the encryption unit 262 to encrypt input data input from a terminal input unit such as the terminal operation unit 21 and the photographing unit 22 using a common key encryption method. The common key is generated by the terminal key generation unit 261 and stored in the terminal storage unit 25 for each input data input from the terminal input unit.

  The encryption unit 262 uses the common key encryption method by using the common key stored in the terminal storage unit 25 and the input data input from the terminal input unit such as the terminal operation unit 21 and the photographing unit 22 by the encryption unit 262. It is encrypted data.

  The encryption key is obtained by encrypting the common key stored in the terminal storage unit 25 by the encryption unit 262 using the public key stored in the terminal storage unit 25 using the public key cryptosystem. The encrypted data and the encryption key of the common key used for encrypting the encrypted data are stored in the terminal storage unit 25 in association with each other.

  The terminal control unit 26 includes one or more processors and their peripheral circuits, and the processor controls the operation of the communication terminal 2 by executing a program stored in the semiconductor memory of the terminal storage unit 25. . The processor and the semiconductor memory may include an independent integrated circuit, a microprocessor, or an ASIC.

  As illustrated in FIG. 2, the terminal control unit 26 includes a terminal key generation unit 261 and an encryption unit 262. Each unit of the terminal control unit 26 is a functional module realized by the processor reading and executing a program describing the processing procedure of each unit stored in the terminal storage unit 25.

  The terminal key generation unit 261 generates a common key for encrypting the input data by a common key encryption method when data is input from the terminal input unit such as the terminal operation unit 21 and the photographing unit 22, and the terminal storage unit 25. Note that the terminal key generation unit 261 first generates a plurality of common keys such as 30, for example, and the number of unused common keys that are not used by the encryption unit 262 is a predetermined number such as 15, for example. If the value is less than, a plurality of common keys may be newly generated so that the number of common keys is the same as the number of initially generated common keys. The terminal key generation unit 261 can generate an encryption key efficiently by generating a plurality of encryption keys at the same time, and can reduce the processing load for generating the encryption key.

  The encryption unit 262 encrypts input data input from a terminal input unit such as the terminal operation unit 21 or the photographing unit 22 by using a common key encryption method using a common key stored in the terminal storage unit 25. In addition, the encryption unit 262 encrypts the common key used to encrypt the input data using the public key encryption method using the public key stored in the terminal storage unit 25. In this embodiment, the encryption unit 262 encrypts input data having large data such as image data by a common key encryption method that is performed by a simple process such as replacement or transposition of AES or the like and has a low processing load. . On the other hand, the common key, which is relatively small data, involves a complicated calculation and thus has a large processing load. However, the common key is highly secure because it cannot be decrypted on the communication terminal 2 that does not have a secret key, such as RSA (registered trademark). Encrypt using the public key cryptosystem. When the encryption unit 262 encrypts the input data and the common key and stores them in the terminal storage unit 25, the encryption unit 262 may erase the original input data and the common key before encryption.

  FIG. 3 is a configuration diagram of the center device 3 according to an embodiment of the present invention. As shown in FIG. 3, the center device 3 includes a center operation unit 31, a center display unit 32, a center communication unit 33, a center storage unit 34, and a center control unit 35.

  The center operation unit 31 includes operation devices such as buttons, a keyboard, and a mouse, and functions as an input device for a monitor to input information to the center device 3.

  The center display unit 32 is configured by a display device such as a liquid crystal display or a touch panel display, and serves as a notification unit that notifies the monitoring staff of the property where the security device 4 that has transmitted the abnormality detection signal is installed, the content of the detected abnormality, and the like. Function. The center display unit 32 displays input data to the communication terminal 2 such as inspection records and image data received from the communication terminal 2 via the center communication unit 33. The center display unit 32 may be integrated with a part of the center operation unit 31 by being configured with a touch panel display.

  The center communication unit 33 performs wireless communication with a communication interface circuit for connecting the center device 3 to the IP network 51 and / or a base station 57 of the mobile phone network 54 similar to the terminal communication unit 24 of the communication terminal 2. A communication interface circuit. The center communication unit 33 sends information received from the communication terminal 2 via the IP network 51 and / or the mobile phone network 54 to the center control unit 35. Further, the center communication unit 33 transmits the information received from the center control unit 35 to the communication terminal 2 via the IP network 51 and / or the mobile phone network 54. In the present embodiment, an example in which the center device 3 communicates with the communication terminal 2 from the IP network 51 via the mobile phone network 54 will be described.

  The center storage unit 34 includes a semiconductor memory such as a ROM and a RAM. The center storage unit 34 may include a magnetic storage medium such as a hard disk and / or an optical storage medium such as a CD-ROM and / or a DVD and an access device thereof. The center storage unit 34 may include a storage device connected from the center communication unit 33 via the communication network 5. The center storage unit 34 stores a computer program and various data for controlling the center device 3, and exchanges such information with the center control unit 35. The program may be provided from the communication network 5 via the center communication unit 33 and stored in the center storage unit 34, or may be provided by a computer-readable storage medium such as CD-ROM and / or DVD, firmware, or the like. Good.

  As shown in FIG. 3, the center storage unit 34 stores user information, security related information, work management information, and a secret key.

  The user information includes personal identification information such as an employee number of an authorized user who can use the communication terminal 2. This personal identification information may be used as user authentication information for authenticating the user of the communication terminal 2. Further, the user information may include information such as a password, a user's fingerprint, a face, or a voiceprint as user authentication information corresponding to each legitimate user's personal identification information.

  The security related information is the same information as that stored in the terminal storage unit 25 of the communication terminal 2 and is stored in the center storage unit 34 in association with the individual identification information of the authorized user.

The work management information is information for managing work such as attendance and leaving of each user.
FIG. 4 is a diagram showing an example of the configuration of work management information in the present embodiment. The work management information includes, for each user's work, personal identification information (ID) of the user who works, terminal identification information (ID) of the communication terminal 2 used for work, and whether he / she went to work / retired accordingly Information on work such as a work flag / no work flag indicating whether or not. Further, the work management information may include information on other work such as work place, work time, and work time, and whether or not a valid work time / work time is set instead of the work / work flag. It may be indicated whether or not he / she has gone to / from work. As illustrated in FIG. 4, the work management information may include a secret key generated for each work.

  The secret key is a decryption key used by the decryption unit 352 to decrypt the encryption key sent from the communication terminal 2 using the public key cryptosystem. The secret key is generated by the center key generating unit 351 when the center device 3 receives from the communication terminal 2 a work start signal indicating the start of work of the user by the center communication unit 33. The secret key is stored for each duty of the user in association with at least one of the personal identification information and terminal identification information of the user of the communication terminal 2. For example, the secret key may be stored as work management information as shown in FIG.

  The center control unit 35 includes one or more processors and their peripheral circuits, and the processor controls the operation of the center device 3 by executing a program stored in the semiconductor memory of the center storage unit 34. .

  As shown in FIG. 3, the center control unit 35 includes a center key generation unit 351 and a decryption unit 352. Each of these units is a functional module realized by the processor reading and executing a program describing the processing procedure of each unit stored in the center storage unit 34.

  When the center communication unit 33 receives a work start signal indicating the start of work of the user from the communication terminal 2, the center key generation unit 351 generates a key pair of a public key and a secret key used in encryption processing by a public key cryptosystem. To do. Of the key pair generated by the center key generation unit 351, the secret key is stored in the center storage unit 34, and the public key is sent to the communication terminal 2 by the center communication unit 33.

  The decryption unit 352 decrypts the encryption key received by the center communication unit 33 from the communication terminal 2 using the secret key stored in the center storage unit 34 by the public key cryptosystem, and makes the original common key. Also, the decryption unit 352 decrypts the encrypted data received from the communication terminal 2 by the center communication unit 33 by using the decrypted common key by the common key encryption method.

  5 and 6 are operation sequence diagrams of the communication terminal 2 and the center device 3 according to an embodiment of the present invention. With reference to FIG. 5 and FIG. 6, an example of the operation of the communication terminal 2 and the center device 3 in the present embodiment will be described along the work flow of the guard.

  When the security guard starts working using the communication terminal 2, in order to start using the communication terminal 2, the security guard inputs the personal ID such as an employee number identifying himself / herself from the terminal operation unit 21 and inputs the work start. . The personal ID is user authentication information as a regular user who uses the communication terminal 2.

  Referring to FIG. 5, the terminal control unit 26 of the communication terminal 2 determines whether or not an input for starting work has been performed from the terminal operation unit 21 (step A101), and if there is no input for starting work (in step A101). No), and waits until work start is input. Then, when the start of work is input from the terminal operation unit 21 (Yes in Step A101), the terminal control unit 26, the personal ID input from the terminal operation unit 21 by the input of work start, and the terminal storage unit 25 A work start signal having a terminal ID that is identification information of itself read from a specific area is generated, and the generated work start signal is transmitted to the center device 3 by the terminal communication unit 24 (step A102). The terminal ID may be input from the terminal operation unit 21 by the user.

  The center control unit 35 of the center device 3 starts using the communication terminal 2 by determining whether or not the center communication unit 33 has received a work start signal indicating the start of work of the user from the communication terminal 2. It is determined whether or not (step B101). When the center communication unit 33 receives the work start signal from the communication terminal 2 (Yes in step B101), the center control unit 35 uses the personal ID of the work start signal received by the center communication unit 33 as the user authentication information. User authentication is performed by comparing with the personal ID of the user information stored in the storage unit (step B102). If this personal ID is present in the user information, the center control unit 35 authenticates the user who has entered the start of work at the communication terminal 2 as an authorized user of the communication terminal 2, and the center storage unit 34. The personal ID and terminal ID of the work start signal are registered in the work management information stored in, and the attendance of the user is registered by setting the corresponding attendance flag to ON (step B103). At this time, the center control unit 35 may register information such as work location and attendance time in the work management information. When user authentication information such as a password is input together with the personal ID in the start of work by the terminal operation unit 21 of the communication terminal 2, the center communication unit 33 displays the user authentication information together with the personal ID in step B101. In step B102, the center control unit 35 collates the user authentication information received by the center communication unit 33 with the user authentication information of the user information stored in the center storage unit 34. User authentication.

  When the center control unit 35 registers the attendance of the user in the work management information, the center key generation unit 351 generates a public / private key pair used for encryption processing by the public key cryptosystem (step B104). The center control unit 35 then communicates the public key of the key pair generated by the center key generation unit 351 together with the security related information corresponding to the personal ID read from the center storage unit 34 by the center communication unit 33 by the communication terminal 2. (Step B105). Further, the center control unit 35 stores the secret key of the key pair generated by the center key generation unit 351 in the center storage unit 34 in association with at least one of the personal ID and the terminal ID (step B106). At this time, the center control unit 35 may register the secret key in the work management information of the center storage unit 34.

  The terminal control unit 26 of the communication terminal 2 determines whether or not the terminal communication unit 24 has received the security related information and the public key from the center device 3 (step A103), and the terminal communication unit 24 has the security related information and the public key. Is not received (No in step A103), the terminal communication unit 24 waits until receiving security-related information and a public key. When the terminal communication unit 24 receives the security related information and the public key (Yes in Step A103), the terminal control unit 26 stores the security related information and the public key received by the terminal communication unit 24 from the center device 3 in the terminal storage unit 25. Store (step A104). As described above, the communication terminal 2 cannot input the security service input data that is required to be confidential until the public key is received. Thereby, the confidentiality of input data is ensured and data leakage is prevented.

  When the security guard inputs work start, the security guard performs security work while displaying the security related information sent from the center apparatus 3 to the communication terminal 2 on the terminal display unit 23 as necessary. The security guard inputs various data using a terminal input unit such as the terminal operation unit 21 and the photographing unit 22 when performing the security service. The input data input by the security guard is, for example, inspection records such as the state of the inspection location, the content of the abnormality, and a memorandum, and image data captured by the imaging unit 22. Hereinafter, a case where image data is input from the imaging unit 22 as input data input from the terminal input unit of the communication terminal 2 will be described. The security guard inputs image data from the imaging unit 22 by inputting an instruction to capture an image to the terminal operation unit 21.

  Referring to FIG. 5, the terminal control unit 26 determines whether an instruction to capture an image is input from the terminal operation unit 21 (step A105). When an instruction to capture an image is input from the terminal operation unit 21 (Yes in Step A105), the terminal control unit 26 captures an image by the capturing unit 22 and acquires image data (Step A106). The terminal key generation unit 261 generates a common key for encrypting the image data with the common key encryption method, and stores it in the terminal storage unit 25 (step A107). The encryption unit 262 encrypts the image data by the common key encryption method using the common key stored in the terminal storage unit 25 to obtain encrypted data, and deletes the original image data (step A108). Then, the encryption unit 262 encrypts the common key used for encrypting the image data by using the public key stored in the terminal storage unit 25 by the public key encryption method, and uses the original common key. The key is deleted (step A109). The encryption unit 262 associates the encrypted data obtained by encrypting the image data with the encryption key obtained by encrypting the common key used for encrypting the encrypted data, and causes the terminal storage unit 25 to store the associated data (Step S25). A110). When the imaging unit 22 acquires a plurality of image data, the terminal control unit 26 repeats Step A105 to Step A110, and a common key is generated for each acquired image data. In step A105, the terminal control unit 26 determines whether or not the public key is stored in the terminal storage unit 25. If the public key is not stored in the terminal storage unit 25, a shooting instruction is input. It is determined that the image has not been captured (No in step A105), and image capturing can be prohibited.

  The security guard captures input data such as image data captured by the capturing unit 22 by capturing an evidence image by the capturing unit 22 and then inputting an instruction to transfer the input data to the terminal operation unit 21 of the communication terminal 2. It can be transferred to the center device 3.

  Referring to FIG. 6, the terminal control unit 26 of the communication terminal 2 determines whether or not an input data transfer instruction has been input from the terminal operation unit 21 (step A111). When an input data transfer instruction is input from the terminal operation unit 21 (Yes in step A111), the terminal control unit 26 uses the terminal communication unit 24 to store encrypted data and encryption stored in association with the terminal storage unit 25. The encryption key is transmitted to the center device 3 together with at least one of the personal ID and terminal ID of the user of the communication terminal 2 (step A112).

  The center control unit 35 of the center device 3 determines whether or not the center communication unit 33 has completed reception of the encrypted data and the encryption key from the communication terminal 2 (step B107), and the center communication unit 33 performs the communication terminal. When the reception of the encrypted data and the encryption key from 2 is completed (Yes in Step B107), the center control unit 35 transmits a reception completion signal to the communication terminal 2 by the center communication unit 33 (Step B108). Then, the decryption unit 352 reads the secret key corresponding to the terminal ID of the communication terminal 2 or the user's personal ID received simultaneously from the center storage unit 34, and reads the encryption key received by the center communication unit 33. The key is used to decrypt the original common key by public key cryptography (step B109). In addition, the decryption unit 352 decrypts the encrypted data into the original image data by the common key encryption method using the decrypted common key (step B110). The center control unit 35 stores the decoded image data in the center storage unit 34 (step B111). Thereafter, the image data stored in the center storage unit 34 may be displayed on the center display unit 32 as needed, or may be stored in the database as a security record.

  The terminal control unit 26 of the communication terminal 2 determines whether or not the transmission of the encrypted data and the encryption key to the center device 3 is completed depending on whether or not the terminal communication unit 24 has received the reception completion signal from the center device 3. Is determined (step A113). If the transmission of the encrypted data and the encryption key is not completed (No in step A113), the terminal control unit 26 waits until the transmission is completed. When the transmission of the encrypted data and the encryption key is completed (Yes in step A113), the terminal control unit 26 can erase the transmitted encrypted data and encryption key stored in the terminal storage unit 25. (Step A114).

  During security, the security guard can repeat input of input data such as photographing of evidence images by the photographing unit 22 of the communication terminal 2 and transfer of input data such as photographed evidence images to the center device 3 as necessary. . And when all the guards shown by the guard schedule are finished and the work is finished, the guards input the work end to the terminal operation unit 21 of the communication terminal 2.

  Referring to FIG. 6, the terminal control unit 26 of the communication terminal 2 determines whether or not the end of work has been input to the terminal operation unit 21 (step A115). When the end of work is input to the terminal operation unit 21 (Yes in step A115), the terminal control unit 26 has at least one of the personal ID and the terminal ID of the user of the communication terminal 2 by the terminal communication unit 24. A work end signal is transmitted to the center device 3 (step A116). At this time, the end of work may be received on condition that there is no encrypted data and encryption key that have not been transferred to the center device 3 in the terminal storage unit 25. Further, the terminal control unit 26 deletes the public key stored in the terminal storage unit 25 (step A117).

  The center control unit 35 of the center device 3 determines whether or not the center communication unit 33 has received a work end signal indicating the end of the user's work from the communication terminal 2, so that the user ends the use of the communication terminal 2. It is determined whether or not (step B112). When the center communication unit 33 receives the work end signal (Yes in Step B112), the center control unit 35 stores work management information corresponding to the personal ID or terminal ID of the work end signal stored in the center storage unit 34. Is set to ON, and the user's leave of work of the communication terminal 2 is registered (step B113). At this time, the center control unit 35 may register information such as leaving time in the work management information. The center control unit 35 deletes the secret key corresponding to the received personal ID or terminal ID from the center storage unit 34 (step B114).

  As described above, the center device according to the present invention newly generates a pair of public key and secret key used in the encryption processing of the public key cryptosystem at the timing when the user starts using the communication terminal. To do. Further, the center device is configured to delete the secret key from the center storage unit at the timing when the use of the communication terminal is finished by the user. Therefore, even if a malicious third party obtains a secret key, a public key and a secret key that are different each time the user of the communication terminal changes are a common key that encrypts the input data of the communication terminal. Therefore, leakage of input data input to the communication terminal can be limited to the range of input data input by one user. In addition, even if the user of the communication terminal becomes a malicious third party, it is possible to reliably prevent the leakage of input data input to the communication terminal by other users. Can be minimized.

  Furthermore, the communication terminal according to the present invention encrypts relatively large input data such as image data input from a terminal input unit such as a photographing unit using a common key with a common key encryption method with a low processing load. The common key, which is relatively small data used for the encryption of the input data, is encrypted using the public key by a public key cryptosystem that is safer but has a large processing load. Therefore, high confidentiality of input data can be ensured while suppressing the load on the communication terminal.

  The center device according to the present invention sends the public key of the generated public / private key pair to the communication terminal, and stores the secret key in the center device. Furthermore, the communication terminal according to the present invention can erase the original input data and the common key after the input data such as image data and the common key are encrypted. As a result, the common key used for encrypting the input data encrypted with the public key in the public key cryptosystem cannot be decrypted on the communication terminal even by the user himself. Can not. Therefore, it is possible to reliably prevent the input data input to the communication terminal from being leaked by the user's hand.

  Further, according to the present invention, input of image data by the photographing unit can be prohibited when the public key is not stored in the terminal storage unit. Therefore, it is possible to prevent highly confidential input data such as image data input from the imaging unit from being stored in the terminal storage unit without being encrypted, and high confidentiality of input data such as image data. Can be secured.

  In addition, the communication terminal according to the present invention deletes the transmitted encrypted data and encryption key from the terminal storage unit when the encrypted data and encryption key stored in the terminal storage unit have been transferred to the center device. . Therefore, since the period during which the encrypted data is stored in the terminal storage unit is limited, input data such as image data may be leaked unless a malicious third party obtains the secret key in an extremely short time. Therefore, the confidentiality of the input data can be further improved.

  The preferred embodiments of the present invention have been described above, but the present invention is not limited to these embodiments. For example, the communication terminal may be configured to transmit a power-on notification signal indicating that the power is turned on to the center device when the power is turned on. In this case, the center device may be configured to generate a key pair of a public key and a secret key with the reception of the power-on notification signal from the communication terminal as the timing when the use of the communication terminal is started. Further, the communication terminal may erase the public key stored in the terminal storage unit when the power is turned off. And a communication terminal may be comprised so that the power-off notification signal which shows that the power supply was cut | disconnected at the time of a power-off may be transmitted to a center apparatus. In this case, the center device may delete the secret key stored in the center storage unit at the timing when the use of the communication terminal ends when the power-off notification signal is received.

  In the above-described embodiment, the encryption key used for the encryption processing of the input data is changed for each work of the user. For example, the center device generates a new encryption key for each work performed by the user during work. May be. In this case, for example, the communication terminal may be configured to transmit a work start signal indicating the start of work to the center device when the security guard selects a security work to be performed by the terminal operation unit. In addition, the communication terminal may transmit a job start signal to the center device when the current time is the start time of each security job indicated by the security schedule. The center device can generate a key pair of a public key and a secret key with the reception of the security service start signal as a timing when the use of the communication terminal is started.

  In the above-described embodiment, an example is described in which a security guard inputs work start to a communication terminal and transmits a work start signal from the communication terminal to the center apparatus. It is not limited to. For example, a security guard inputs work start to a communication device that is different from a communication terminal such as a personal computer installed at the office where he / she works. You may make it input the terminal ID of a terminal and transmit a work start signal from this communication apparatus to a center apparatus.

  Furthermore, in the communication terminal, it is not necessary to encrypt all input data from the terminal input unit such as the terminal operation unit and the photographing unit by the encryption unit, only the input data (image data) from the photographing unit is encrypted. You may make it do. In this case, the input data input from the terminal operation unit can be repeatedly checked and updated by the input security guard, so that the accuracy of the input data can be improved, and It is possible to reliably prevent leakage of input data such as image data from the imaging unit with high secrecy.

DESCRIPTION OF SYMBOLS 1 Security system 2 Communication terminal 21 Terminal operation part 22 Image | photographing part 23 Terminal display part 24 Terminal communication part 25 Terminal memory | storage part 26 Terminal control part 261 Terminal key generation part 262 Encryption part 3 Center apparatus 31 Center operation part 32 Center display part 33 Center communication unit 34 Center storage unit 35 Center control unit 351 Center key generation unit 352 Decryption unit 4 Security device 5 Communication network 51 Network 52 Router 53 Access point 54 Mobile phone network 55-57 Base station

Claims (9)

A communication system having a communication terminal having a terminal input unit and a center device capable of communicating with the communication terminal,
The center device is
A center key generating unit that generates a pair of public key and secret key of a public key cryptosystem at a timing when the user starts using the communication terminal;
A center communication unit that transmits the generated public key to the communication terminal and receives a work start signal notifying the start of work and a work end signal notifying the end of work from the communication terminal;
A center storage unit for storing the generated secret key,
The center key generation unit generates the public key and the secret key with the reception of the work start signal from the communication terminal as a timing when the user starts using the communication terminal,
The communication terminal is
A terminal communication unit that receives the public key from the center device and transmits the work start signal and the work end signal to the center device;
A terminal key generation unit that generates a common key of the common key cryptosystem;
An encryption unit that encrypts input data input from the terminal input unit using the common key to obtain encrypted data, and encrypts the common key using the public key to obtain an encryption key;
A terminal storage unit that stores the received public key, the encrypted encrypted data, and the encryption key associated with the encrypted data;
When the center communication unit receives the work end signal from the communication terminal, the center device deletes the secret key from the center storage unit.   The communication system according to claim 1, wherein the terminal key generation unit generates the common key when data is input from the terminal input unit.   The terminal key generation unit generates a first predetermined number of the common keys, and the number of unused common keys that are not used by the encryption unit among the generated first predetermined number of common keys is: 2. The communication system according to claim 1, wherein when a second predetermined number smaller than the first predetermined number is fallen, the common key is newly generated and used as the first predetermined number of common keys. The terminal input unit includes a photographing unit that acquires image data as the input data,
The communication system according to any one of claims 1 to 3, wherein the encryption unit encrypts the image data input by the photographing unit using the common key.   The communication system according to claim 4, wherein input of the image data by the photographing unit is prohibited when the public key is not stored in the terminal storage unit. The terminal communication unit transmits the encrypted data and the encryption key stored in the terminal storage unit to the center device,
The communication terminal deletes the encrypted data and the encryption key that the terminal communication unit has completed transmission from the terminal storage unit,
The center communication unit receives the encrypted data and the encryption key from the communication terminal,
The center device decrypts the received encryption key using the secret key stored in the center storage unit to form the common key, and decrypts the received encrypted data using the decrypted common key The communication system according to any one of claims 1 to 5, further comprising a decoding unit. The terminal input unit inputs user authentication information of a user,
The center key generation unit generates the pair of public key and secret key when the center communication unit receives the user authentication information from the communication terminal as a timing when the use of the communication terminal is started. The communication system according to any one of claims 1 to 6. A method performed by a communication terminal having a terminal input unit and a center device capable of communicating with the communication terminal,
The center device is
The center communication unit receives a work start signal notifying the start of work from the communication terminal as a timing when the user starts using the communication terminal; and
A step of generating a pair of public key and secret key of a public key cryptosystem at a timing when a center key generation unit starts using the communication terminal by a user;
The center communication unit transmitting the generated public key to the communication terminal;
A center storage unit storing the generated secret key;
The center communication unit receiving a work end signal notifying the end of work from the communication terminal;
When the center communication unit receives the work end signal from the communication terminal, the secret key is deleted from the center storage unit,
The communication terminal is
A terminal communication unit transmitting the work start signal to the center device;
The terminal communication unit receiving the public key from the center device;
A step of generating a common key of a common key cryptosystem by a terminal key generation unit;
An encryption unit encrypting the input data input from the terminal input unit using the common key to obtain encrypted data, and encrypting the common key using the public key to obtain an encryption key; ,
A terminal storage unit storing the received public key, the encrypted encrypted data, and the encryption key associated with the encrypted data;
The terminal communication unit includes a step of transmitting the work end signal to the center device. A communication program executed by a communication terminal having a terminal input unit and a center device capable of communicating with the communication terminal,
In the center device,
The center communication unit receives a work start signal notifying the start of work from the communication terminal as a timing when the user starts using the communication terminal, and
A procedure for generating a pair of public key and secret key of the public key cryptosystem at a timing when the center key generation unit starts using the communication terminal by the user;
The center communication unit transmits the generated public key to the communication terminal;
A procedure in which the center storage unit stores the generated secret key;
The center communication unit receives a work end signal notifying the end of work from the communication terminal,
When the center communication unit receives the work end signal from the communication terminal, the center communication unit deletes the secret key from the center storage unit, and
In the communication terminal,
A procedure in which the terminal communication unit transmits the work start signal to the center device;
A procedure in which the terminal communication unit receives the public key from the center device;
A procedure in which the terminal key generation unit generates a common key of the common key cryptosystem;
A procedure in which an encryption unit encrypts input data input from the terminal input unit using the common key to obtain encrypted data, and encrypts the common key using the public key to obtain an encryption key; ,
A procedure in which a terminal storage unit stores the received public key, the encrypted encrypted data, and the encryption key associated with the encrypted data;
A communication program for causing the terminal communication unit to execute a procedure of transmitting the work end signal to the center device.

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