Patent Publication Number: US-2022239642-A1

Title: Apparatus management system and authentication method

Description:
TECHNICAL FIELD 
     The present disclosure relates to an apparatus management system that manages an apparatus and an authentication method. 
     BACKGROUND ART 
     Patent Document 1 discloses an apparatus management system. In the publication, a mobile terminal and a management server communicate with each other through the Internet. 
     Patent Document 2 discloses the connection between a server and apparatuses. In Patent Document 2, a high-speed supplementary service center receives a delivery request for high-speed content as upload low-speed data from a terminal through a low-speed communication network. Then, the high-speed supplementary service center transmits the received upload low-speed data to a high-speed content delivery server through a virtual private network and a dedicated line. The high-speed supplementary service center refers to a route allocation condition related to the header attribute or data volume of download data and transmits the download data to the terminal, from which the request was received through the virtual private network and the dedicated line, through a high-speed communication channel or a low-speed communication line in accordance with the route allocation condition. 
     PRIOR ART DOCUMENTS 
     Patent Documents 
     
         
         Patent Document 1: Japanese Laid-Open Patent Publication No. 2016-133294 
         Patent Document 2: Japanese Laid-Open Patent Publication No. 2002-27009 
       
    
     SUMMARY OF THE INVENTION 
     Problems that the Invention is to Solve 
     It is preferred that communication between a server and an apparatus be performed in a secure manner. However, when multiple apparatuses are connected to the server, the acquirement of a device certificate for each apparatus is burdensome and time-consuming. This raises the cost of an authentication process. 
     It is an objective of the present disclosure to provide an apparatus management system and an authentication method that reduce the cost of an authentication process. 
     Means for Solving the Problems 
     An apparatus management system includes a management device that remotely manages apparatus information related to an apparatus, and an information communication device connected to the apparatus to obtain the apparatus information and transmit the apparatus information to the management device by communicating with the management device through a communication network. The management device is configured to be connected to the information communication device through a closed network that connects the management device and the information communication device in a secure state, and the closed network is isolated in terms of access from an open network in the communication network. When the management device is connected to the information communication device through the closed network, the management device is configured to perform authentication determination on the information communication device and transmit a device certificate to the information communication device after completing authentication of the information communication device. The device certificate includes information indicating that the information communication device has been authenticated and encryption information for encrypting information that is transmitted from the information communication device to the management device. 
     A user needs to take burdensome procedures to obtain a device certificate for each apparatus. With the above configuration, when the management device is connected to the information communication device, the management device performs authentication determination on the information communication device. This simplifies the authentication process of the apparatus and reduces the cost for authenticating the apparatus. 
     In the above apparatus management system, the information communication device is configured to communicate with the management device and transmit the apparatus information in information packets encrypted based on the device certificate to the management device through the open network. With this configuration, the transmitted apparatus information is secure. 
     In the above apparatus management system, when the information communication device is connected to the management device through the closed network, the information communication device transmits first authentication information for verifying the information communication device to the management device, and the management device is configured to authenticate the information communication device with information for authenticating the information communication device that is second authentication information stored in advance in a storage unit and the first authentication information obtained from the information communication device, and transmit the device certificate to the information communication device after completing authentication of the information communication device. 
     With this configuration, the management device authenticates the information communication device with the information for authenticating the information communication device, namely, the second authentication information, which is stored in advance in the storage unit, and the first authentication information, which is obtained from the information communication device. This avoids the authentication of a fraudulent information communication device. 
     In the above apparatus management system, the information communication device stores unique identification information of the information communication device as the first authentication information, and the management device is configured to store identification information for authentication in association with the unique identification information as the second authentication information. 
     With this configuration, authentication determination on the information communication device is performed with the unique identification information, thus simplifying authentication. 
     In the above apparatus management system, the information communication device is incorporated in the apparatus. 
     With this configuration, the entire structure including the apparatus and the information communication device can be compact. 
     In the above apparatus management system, the information communication device is incorporated in an air conditioner that serves as the apparatus. 
     With this configuration, the air conditioner including the information communication device can be compact. 
     In an authentication method for authenticating an information communication device in an apparatus management system, the apparatus management system includes a management device that remotely manages apparatus information related to an apparatus and the information communication device connected to the apparatus to obtain the apparatus information and transmit the apparatus information to the management device by communicating with the management device through a communication network. The management device is configured to be connected to the information communication device through a closed network that connects the management device and the information communication device in a secure state, and the closed network is isolated in terms of access from an open network in the communication network. The authentication method includes: when the management device is connected to the information communication device through the closed network, performing authentication determination on the information communication device and, transmitting a device certificate to the information communication device after completing authentication of the information communication device, the device certificate including information indicating that the information communication device has been authenticated and encryption information for encrypting information that is transmitted from the information communication device to the management device. 
     The user needs to take burdensome procedures to obtain the device certificate for each apparatus. With the above configuration, when the management device is connected to the information communication device, the management device performs authentication determination on the information communication device. This simplifies the authentication process of the apparatus and reduces the cost of the authentication process. 
     The above authentication method further includes: a first step for transmitting first authentication information for verifying the information communication device to the management device with the information communication device when the information communication device is connected to the management device through the closed network in a secure connection state; a second step for authenticating the information communication device with the management device  3  in the secure connection state using information for authenticating the information communication device that is second authentication information stored in advance in a storage unit and the first authentication information obtained from the information communication device; and a third step for transmitting, a device certificate to the information communication device, in the secure connection state with the management device after completing authentication of the information communication device, the device certification including information indicating that the information communication device has been authenticated and encryption information for encrypting information that is transmitted from the information communication device to the management device. 
     This configuration avoids the authentication of a fraudulent information communication device. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of an apparatus management system. 
         FIG. 2  is a block diagram of an information communication device. 
         FIG. 3  is a table stored in a management device. 
         FIG. 4  is a sequence diagram showing communication between the management device and the information communication device. 
         FIG. 5  is a flowchart of an initializing process. 
     
    
    
     MODES FOR CARRYING OUT THE INVENTION 
     An apparatus management system  1  according to the present embodiment will now be described. 
     The apparatus management system  1  manages apparatus information  10  for apparatuses  2  that are connected to a communication network NA. The communication network NA includes an open network NB and a closed network NC. There is no restriction for connection to the open network NB. The Internet is an example of the open network NB. The closed network NC is isolated in terms of access from the open network NB in the communication network NA. 
     The closed network NC includes a dedicated communication network managed by a specific business entity and a virtual private network (hereafter referred to as VPN). The VPN includes an Internet VPN that operates on the Internet and an IP-VPN that uses an IP line provided by a specific business entity. In the present embodiment, the Internet VPN is schematically shown as a tunnel (broken line in  FIG. 1 ). 
     Examples of the apparatuses  2  include an air conditioner, a refrigerator, an air cleaner, and the like. The apparatus information  10  includes at least a unique identification number of each apparatus  2  and apparatus operation information based on the operation of each apparatus  2 . The apparatus operation information includes at least one of running information, diagnostic information, environmental information, and failure information of the corresponding apparatus  2 . The running information includes at least one of accumulated power source driving time, activation frequency, and operating temperature of the apparatus  2 . The environmental information refers to information about the ambient environment of the corresponding apparatus  2  and includes at least one of temperature, humidity, and the atmospheric pressure. The environmental information may be obtained by a sensor arranged on the apparatus  2 . The apparatus  2  includes a camera for self-diagnosis. The diagnostic information of the apparatus  2  includes captured images (including video) of the camera. 
     The apparatus management system  1  will now be described with reference to  FIG. 1 . The apparatus management system  1  includes a management device  3  and an information communication device  4 . 
     The management device  3  remotely manages the apparatus information  10  related to each apparatus  2 . The management device  3  manages the apparatus information  10  for each apparatus  2  through the information communication device  4  (described later) connected to the apparatus  2 . Preferably, the management device  3  manages the apparatus information  10  for each apparatus  2 . 
     One or more terminals for accessing the apparatus information  10  are connected to the management device  3 . The terminals include a personal computer, a laptop computer, a mobile phone, and a smartphone. 
     A first example of the apparatus information  10  managed by the management device  3  will now be described. The apparatus  2  is an air conditioner including a compressor. The apparatus  2  records the running information about the compressor whenever operated or in predetermined intervals. The running information is one type of the apparatus information  10 . Examples of the running information include at least one of the activation frequency of the compressor, the accumulated driving time of the compressor, and the maximum voltage value. The running information is transferred to the management device  3  through the information communication device  4 . The management device  3  stores the running information for each apparatus  2  together with date and time the running information was transferred. Further, the management device  3  may determine that an apparatus  2  has an anomaly from the managed running information of the apparatus  2 . The management device  3  may notify a terminal of an apparatus anomaly when an anomaly of the apparatus  2  is determined. Further, the management device  3  may estimate the life expectancy of an apparatus  2  from the managed running information of the apparatus  2 . 
     A second example of the apparatus information  10  managed by the management device  3  will now be described. The apparatus  2  is an air conditioner including a camera for capturing images of a drain pan. The drain pan collects water that condenses on a heat exchanger. The apparatus  2  captures an image of the drain pan and records the captured image whenever operated or in predetermined intervals. The captured image is one type of the apparatus information  10 . The captured image is transferred to the management device  3  through the information communication device  4 . The management device  3  stores the captured images of each apparatus  2  together with the date and time the captured images were transferred. Further, the management device  3  may determine that an apparatus  2  has an anomaly from the managed captured image of the apparatus  2 . The management device  3  may notify a terminal of an apparatus anomaly when an anomaly of the apparatus  2  is determined. 
     Information Communication Device 
     The information communication device  4  will now be described with reference to  FIG. 2 . 
     The information communication device  4  is connected to the apparatus  2 . The information communication device  4  obtains the apparatus information  10  from the apparatus  2 . The information communication device  4  transmits the apparatus information  10 , which is obtained from the apparatus  2 , to the management device  3 . 
     The information communication device  4  may be incorporated in the apparatus  2 . For example, the information communication device  4  is incorporated in an air conditioner serving as the apparatus  2 . The information communication device  4  may be accommodated in a case that covers the apparatus  2 . The information communication device  4  may be located outside the case of the apparatus  2 . The information communication device  4  may be connected to the apparatus  2  by a cable or through wireless communication. 
     The information communication device  4  is connected to the communication network NA. The information communication device  4  is connected to the management device  3  through the closed network NC when initialized. The initialization sets the connection of the apparatus  2  and the management device  3 . The initialization is performed when the apparatus  2  is installed at a location where the apparatus  2  is used. 
     When the information communication device  4  is connected to the management device  3  through the closed network NC, the information communication device  4  transmits first authentication information  11  for verifying the information communication device  4  to the management device  3 . 
     The information communication device  4  stores unique identification information of the information communication device  4  as the first authentication information  11 . The identification information of the information communication device  4  may include identification information of the apparatus  2  connected to the information communication device  4 . After transmitting the first authentication information  11 , the information communication device  4  is authenticated by the management device  3  as will be described later and receives a device certificate  13  from the management device  3 . After the information communication device  4  obtains the device certificate  13  from the management device  3 , the information communication device  4  cuts off the connection with the closed network NC. 
     After the information communication device  4  obtains the device certificate  13 , the information communication device  4  communicates with the management device  3  through the open network NB. The information communication device  4  uses the device certificate  13  to transmit the apparatus information  10  of the apparatus  2  to the management device  3  through the open network NB. Specifically, the information communication device  4  transmits the apparatus information  10  in information packets encrypted based on the device certificate  13  to the management device  3 . Thus, the information communication device  4  transmits the apparatus information  10  through the open network NB in a state in which a high level of security is ensured. 
     An example of a specific configuration of the information communication device  4  will now be described. 
     As shown in  FIG. 2 , the information communication device  4  includes a communication unit  5  and a storage unit  6 . The communication unit  5  is configured to perform first communication through the open network NB and second communication through the closed network NC and switch between the first communication and the second communication. The first communication is, for example, TCP/IP communication. The second communication is, for example, communication by VPN connection based on the Security Architecture for Internet Protocol (IPsec). 
     The information communication device  4  includes a router that is connectable under TCP/IP and IPsec. The storage unit  6  of the information communication device  4  stores IP addresses for TCP/IP communication. The storage unit  6  of the information communication device  4  also stores information used for IPsec, namely, common key information, identification information of the management device  3 , an authentication method, an encryption method, and network information/netmask information of the route to the management device  3 . The information communication device  4  communicates with the management device  3  through the second communication during initialization. When the information communication device  4  obtains the device certificate  13 , the information communication device  4  switches the connection between the information communication device  4  and the management device  3  from the second communication to the first communication. 
     Management Device 
     The management device  3  remotely manages the apparatus information  10  related to the apparatuses  2  as described above. Further, when connected to the information communication device  4  through the closed network NC, the management device  3  performs authentication determination on the information communication device  4 . The authentication determination determines whether the information communication device  4  is authentic. 
     The management device  3  includes a storage unit  7  storing information, an information communication unit  8 , and a control unit  9 . The control unit  9  performs at least an authentication determination process (refer to step S 13  in  FIG. 5 ) for determining whether the information communication device  4  is authentic. 
     The control unit  9  may be circuitry including: 1) one or more processors that execute various processes according to a computer program (software); 2) one or more dedicated hardware circuits (application-specific integrated circuits: ASIC) that execute at least part of various processes, or 3) a combination thereof. The processor includes a CPU and memory such as RAM and ROM. The memory stores program code or commands configured to cause the CPU to execute processes. The memory, or computer-readable media, include any type of media that is accessible by general-purpose computers or dedicated computers. 
     In one example, the information communication unit  8  includes a router that is connectable under TCP/IP and IPsec. The information communication unit  8  stores IP addresses for TCP/IP communication. The information communication unit  8  also stores information used for IPsec, namely, common key information, identification information of the management device  3 , an authentication method, an encryption method, and network information/netmask information of the route to the information communication device  4  that is the subject of communication. The information communication unit  8  is configured to perform the first communication through the open network NB and the second communication through the closed network NC and switch between the first communication and the second communication. The information communication unit  8  communicates with an unauthenticated information communication device  4  through the second communication. When the information communication device  4  is authenticated, the information communication unit  8  switches the connection with the information communication device  4  from the second communication to the first communication. The common key information is identical to the common key information stored in the information communication device  4 . The authentication method and the encryption method are the same as the authentication method and the encryption method stored in the information communication device  4 . 
     The storage unit  7  of the management device  3  stores the apparatus information  10 . The apparatus information  10  stored in the management device  3  is transmitted from the information communication devices  4  connected to the management device  3 . The management device  3  manages the apparatus information  10  for each apparatus  2 . 
     The management device  3  uses second authentication information  12  to authenticate each information communication device  4 . The second authentication information  12  is stored in advance in the storage unit  7 . The second authentication information  12  is input in advance to the management device  3  through a terminal connected to the management device  3 . The management device  3  stores the second authentication information  12  for the information communication devices  4  connected to the management device  3 . 
     The second authentication information  12  is associated with unique identification information of the information communication device  4 . The second authentication information  12  has a predetermined relationship with the first authentication information  11 . 
     The second authentication information  12  may be identical to the first authentication information  11 . The second authentication information  12  may include the first authentication information  11 . The second authentication information  12  may have a predetermined arithmetic relationship with the first authentication information  11 . For example, the sum of the second authentication information  12  and the first authentication information  11  may be a predetermined integer value. 
       FIG. 3  is an example of a table stored in the management device  3 . In the table, a management number is associated with each piece of second authentication information  12 . In the example, the second authentication information  12  is the serial number or the MAC address of the information communication device  4 . In the example, the second authentication information  12  is further related to the model number of the apparatus  2  connected to the information communication device  4 . 
     The second authentication information  12  may be a single number as shown in  FIG. 3  or sets of numbers. For example, the second authentication information  12  may be a set of three numbers such as “11,” “12,” and “13”. 
     The control unit  9  of the management device  3  performs authentication determination on each information communication device  4  in accordance with the second authentication information  12  and the first authentication information  11  obtained from the information communication device  4 . When the first authentication information  11  and the second authentication information  12  have a predetermined relationship, the control unit  9  authenticates the information communication device  4 . When the first authentication information  11  and the second authentication information  12  do not have the predetermined relationship, the control unit  9  does not authenticate the information communication device  4 . 
     Before the authentication determination is performed on the information communication device  4 , the second authentication information  12  for the information communication device  4  that is authenticated is selected and used as a reference for the authentication determination. The second authentication information  12  is selected by a user of the terminal connected to the management device  3 . 
     Specific examples of the authentication determination performed by the management device  3  will now be described. 
     When the second authentication information  12  is identical to the first authentication information  11 , the control unit  9  gives a determination as follows. When determining that the first authentication information  11  obtained from the information communication device  4  is identical to the second authentication information  12 , the control unit  9  authenticates the information communication device  4  that transmitted the first authentication information  11 . 
     When the second authentication information  12  includes the first authentication information  11 , the control unit  9  gives a determination as follows. When determining that the second authentication information  12  includes the first authentication information  11  obtained from the information communication device  4 , the control unit  9  authenticates the information communication device  4  that transmitted the first authentication information  11 . 
     When the sum of the second authentication information  12  and the first authentication information  11  is a predetermined integer value, the control unit  9  gives a determination as follows. When determining that the sum of the first authentication information  11  obtained from the information communication device  4  and the second authentication information  12  is a predetermined integer value, the control unit  9  authenticates the information communication device  4  that transmitted the first authentication information  11 . 
     The management device  3  transmits the device certificate  13  to the information communication device  4  after completing the authentication of the information communication device  4 . The device certificate  13  includes information indicating that the information communication device  4  has been authenticated and encryption information for encrypting information transmitted from the information communication device  4  to the management device  3 . 
     The control unit  9  of the management device  3  generates a private key and a public key corresponding to the authenticated information communication device  4  after completing the authentication of the information communication device  4 . The private key is substantially the only key that can decrypt information encrypted with the public key. The private key is stored in the storage unit  7  in association with the authenticated information communication device  4 . The public key is transmitted to the authenticated information communication device  4 . The public key is included in the device certificate  13  transmitted to the information communication device  4 . 
     When receiving encrypted apparatus information  10  from an information communication device  4  through the open network NB, the control unit  9  of the management device  3  identifies the information communication device  4  from information of the information communication device  4 . The management device  3  selects the private key that is unique to the identified information communication device  4 . The management device  3  uses the selected private key to decrypt the encrypted apparatus information  10  transmitted from the information communication device  4 . 
     Authentication Method 
     An authentication method for authenticating the information communication device  4  will now be described with reference to  FIGS. 4 and 5 . 
     When the management device  3  and the information communication device  4  are connected through the closed network NC, the management device  3  performs authentication determination on the information communication device  4 . 
     The management device  3  transmits the device certificate  13  to the information communication device  4  after completing the authentication of the information communication device  4 . The device certificate  13  includes information indicating that the information communication device  4  has been authenticated and encryption information for encrypting information transmitted from the information communication device  4  to the management device  3 . 
     Specifically, as shown in  FIG. 4 , in first step S 1 , when the information communication device  4  is connected to the management device  3  through the closed network NC in a secure connection state, the information communication device  4  transmits the first authentication information  11  for verifying the information communication device  4  to the management device  3 . 
     In second step S 2 , the management device  3  performs authentication determination on the information communication device  4  in the secure connection state with information for authenticating the information communication device  4 , namely, the second authentication information  12 , which is stored in advance in the storage unit  6 , and the first authentication information  11 , which is obtained from the information communication device  4 . 
     In third step S 3 , the management device  3  transmits the device certificate  13  to the information communication device  4  in the secure connection state after completing the authentication of the information communication device  4 . When the information communication device  4  receives the device certificate  13 , the information communication device  4  connects to the open network NB. 
     After the information communication device  4  is authenticated, the information communication device  4  transmits the apparatus information  10  to the management device  3  through the open network NB. The information communication device  4  may transmit the apparatus information  10  in predetermined intervals. 
       FIG. 5  is a flowchart of an initializing process performed by the information communication device  4 . The initializing process is performed during installation of the apparatus  2 . A program for the initializing process may be stored in the information communication device  4  or a terminal that is connected to the information communication device  4  to control the information communication device  4 . 
     In step S 11 , the information communication device  4  is connected to the management device  3  through the closed network NC. For example, a terminal connected to the information communication device  4  may instruct the information communication device  4  to be connected to the management device  3  through the closed network NC. Further, a terminal connected to the management device  3  instructs the management device  3  to select the second authentication information  12  for the information communication device  4 . 
     In step S 12 , the terminal connected to the information communication device  4  instructs the information communication device  4  to transmit the first authentication information  11  to the management device  3 . The information communication device  4  enters a standby state and waits for a reply from the management device  3 . During the standby period, the management device  3  performs authentication determination on the information communication device  4  with the first authentication information  11 , which is transmitted from the information communication device  4 , and the second authentication information  12 . When the first authentication information  11  and the second authentication information  12  have the predetermined relationship, the management device  3  authenticates the information communication device  4 . When the first authentication information  11  and the second authentication information  12  do not have the predetermined relationship, the management device  3  does not authenticate the information communication device  4 . When the information communication device  4  is authenticated, the management device  3  transmits the device certificate  13  to the information communication device  4 . 
     In step S 13 , the information communication device  4  receives the device certificate  13 . 
     In step S 14 , upon receipt of the device certificate  13 , the information communication device  4  cuts off the connection with the management device  3  through the closed network NC. 
     In step S 15 , the information communication device  4  is connected to the open network NB when transmitting the apparatus information  10  for the apparatus  2 . The information communication device  4  encrypts the apparatus information  10  with the public key and transmits the encrypted apparatus information  10  to the management device  3 . The management device  3  decrypts the encrypted apparatus information  10  with the private key and stores the apparatus information  10 . 
     The operation of the present embodiment will now be described. 
     A database including the apparatus information  10  from the apparatuses  2  will be useful for improving the apparatuses  2 . However, the apparatuses  2  cannot be appropriately improved when the apparatus information  10 , which is related to failures and anomalies, is falsified. Thus, it is preferable that the apparatus information  10  for the apparatuses  2  be transmitted to the management device  3  in a secure state. Preferably, the apparatuses  2  are each connected to the management device  3  by a dedicated line. However, when more apparatuses  2  are connected to the dedicated line, the fee for using the dedicated line will increase and raise the cost for using dedicated line. 
     A system that reduces costs may use a certification authority that authenticates the apparatuses  2 . Each apparatus  2  that is authenticated uses the device certificate  13  issued upon authentication to communicate with the management device  3  on the open network NB. Such a system ensures security and reduces costs. However, the authentication of each apparatus  2  when manufactured in a factory is burdensome. Specifically, the user will have to take the necessary procedures to obtain the device certificate  13  for each apparatus  2 . In this case, the user when the apparatuses  2  are manufactured is the manufacturer of the apparatuses  2 . 
     In the present embodiment, when each apparatus  2  is installed and connected to the management device  3  through the communication network NA, the management device  3  performs authentication determination on the information communication device  4  when the apparatus  2  is connected to the closed network NC via the information communication device  4 . When the information communication device  4  is authenticated, the device certificate  13  is transmitted to the information communication device  4  through the closed network NC. In such an authentication method, the apparatus  2  or the information communication device  4  does not need to be connected to the communication network NA when manufactured. This simplifies the manufacturing steps. When the apparatus  2  is installed and connected to the communication network NA via the information communication device  4 , the information communication device  4  is authenticated. In this manner, the process for connecting the apparatus  2  to the communication network NA and the process for authenticating the information communication device  4  are performed through the same series of steps. This increases the efficiency of the authentication process. 
     The present embodiment has the following advantages. 
     (1) In the apparatus management system  1 , when the management device  3  is connected to an information communication device  4  through the closed network NC, the management device  3  performs authentication determination on the information communication device  4 . When completing the authentication of the information communication device  4 , the management device  3  transmits the device certificate  13  to the information communication device  4 . 
     A user needs to take burdensome procedures to obtain the device certificate  13  for each apparatus  2 . With the above configuration, when the management device  3  is connected to the information communication device  4 , the management device  3  performs authentication determination on the information communication device  4 . This simplifies the authentication process of the apparatus  2  and reduces the cost for authenticating the apparatus  2 . 
     (2) In the apparatus management system  1 , the information communication device  4  communicates with the management device  3  and transmits the apparatus information  10  in information packets encrypted based on the device certificate  13  to the management device  3  through the open network NB. With this configuration, the transmitted apparatus information  10  is more secure than when the transmitted apparatus information  10  is not encrypted. 
     (3) In the apparatus management system  1 , when the information communication device  4  is connected to the management device  3  through the closed network NC, the information communication device  4  transmits the first authentication information  11  for verifying the information communication device  4  to the management device  3 . The management device  3  authenticates the information communication device  4  with the information for authenticating the information communication device  4 , namely, the second authentication information  12 , which is stored in advance in the storage unit  6 , and the first authentication information  11 , which is obtained from the information communication device  4 . The management device  3  transmits the device certificate  13  to the information communication device  4  after completing the authentication of the information communication device  4 . 
     With this configuration, the management device  3  authenticates the information communication device  4  with the information for authenticating the information communication device  4 , namely, the second authentication information  12 , which is stored in advance in the storage unit  6 , and the first authentication information  11 , which is obtained from the information communication device  4 . This avoids the authentication of a fraudulent information communication device  4 . 
     (4) In the apparatus management system  1 , each information communication device  4  stores unique identification information of the information communication device  4  as the first authentication information  11 , and the management device  3  stores identification information for authentication in association with the identification information as the second authentication information  12 . With this configuration, authentication determination on the information communication device  4  is performed with the unique identification information, thus simplifying authentication. 
     (5) In the apparatus management system  1 , the information communication device  4  is incorporated in the apparatus  2 . With this configuration, the entire structure, including the apparatus  2  and the information communication device  4 , can be compact. 
     (6) When the apparatus  2  is an air conditioner, the information communication device  4  may be incorporated in the air conditioner, which serves as the apparatus  2 . With this configuration, the air conditioner including the information communication device  4  can be compact. 
     (7) In the authentication method for authenticating the information communication device  4 , when the management device  3  is connected to the information communication device  4  through the closed network NC, the management device  3  performs authentication determination on the information communication device  4 . Then, after completing the authentication of the information communication device  4 , the management device  3  transmits the device certificate  13  to the information communication device  4 . The device certificate  13  includes information indicating that the information communication device  4  has been authenticated and encryption information for encrypting information that is transmitted from the information communication device  4  to the management device  3 . 
     The user needs to take burdensome procedures to obtain the device certificate  13  for each apparatus  2 . With the above configuration, when the management device  3  is connected to the information communication device  4 , the management device  3  performs authentication determination on the information communication device  4 . This simplifies the authentication process of the apparatus  2  and reduces the cost of the authentication process. 
     (8) In the authentication method, in the first step, when the information communication device  4  is connected to the management device  3  through the closed network NC in a secure connection state, the information communication device  4  transmits the first authentication information  11  for verifying the information communication device  4  to the management device  3 . In the second step, the management device  3  authenticates the information communication device  4  in the secure connection state with the information for authenticating the information communication device  4 , namely, the second authentication information  12 , which is stored in advance in the storage unit  6 , and the first authentication information  11 , which is obtained from the information communication device  4 . In the third step, after completing the authentication of the information communication device  4 , the management device  3  transmits the device certificate  13  to the information communication device  4  in the secure connection state. The device certificate includes information indicating that the information communication device  4  has been authenticated and encryption information for encrypting information that is transmitted from the information communication device  4  to the management device  3 . 
     With this configuration, the management device  3  authenticates the information communication device  4  with the second authentication information  12 , which is stored in advance in the storage unit  6 , and the first authentication information  11  obtained from the information communication device  4 . This avoids the authentication of a fraudulent information communication device  4 . 
     Modifications 
     In addition to the above embodiment, the apparatus management system  1  of the present disclosure may be implemented by, for example, the modifications described below or by combining at least two modifications as long as the modifications are consistent with each other. 
     In the above embodiment, the information communication device  4  performs communication through VPN connection under IPsec as an example of the second communication through the closed network NC. However, the example of the second communication through the closed network NC is not limited. Other examples of the second communication performed through the closed network NC include IP-VPN, dedicated lines, and the like. 
     In the embodiment, after the authentication of the information communication device  4 , the information communication device  4  transmits the apparatus information  10  to the management device  3  through the open network NB. In this case, the apparatus information  10  transmitted from the information communication device  4  may renew the device certificate  13 . 
     Although the present device according to the embodiment has been described above, it will be understood that various changes in form and details can be made without departing from the spirit and scope of the present device in the claims.