JP2005332201A - Network, network management system, communication device, password automatic change method used for those listed items - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a network capable of preventing leakage of a new password to a third party and improving security. <P>SOLUTION: In the public network 100 connecting a network management system 1, when changing the password of communication devices 2-1 to 2-n, the password is independently produced and memorized by each device of the network management system 1 and the communication devices 2-1 to 2-n with the same content on the basis of information simultaneously obtained by a plurality of devices such as broadcasting data broadcasted from a broadcast distribution system 3 via a broadcasting network 101 so that leakage of password information on the network is prevented, and its security of the password in the network can be improved. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a network, a network management device, a communication device, and a password automatic change method used therefor, and in particular, a method for changing a password of a communication device in a network in which the communication device and a network management device that remotely operates the communication device are connected. About.

  Conventionally, as this type of password changing method, when automatically changing the password of each communication device between the network management device (service server) and each communication device (information terminal device), the network management device or communication There is a method of changing the new password based on a certain condition in any of the devices and notifying the opposite destination of the content of the new password after the change (for example, see Patent Document 1).

  When the change is made from the network management device side, the contents of the new password are notified to the communication device via the network to which both devices are connected. If the communication device is changed, the content of the new password is notified to the network management device via the network in the same manner as described above.

JP 2003-085148 A

  In the conventional password changing method described above, in the case of the technique described in Patent Document 1, the communication device is connected between a network management device (service server) and a communication device (information terminal device) connected via a network. When the password information is automatically changed, the contents of the changed new password are transmitted / received via the network.

  As described above, in the method of transmitting and receiving password information via the network, if data passing through the network is monitored by a third party, there is a risk that the password information of the communication device may be leaked to the outside, and security is reduced. There is a problem of end up.

  Therefore, an object of the present invention is to solve the above-mentioned problems, prevent leakage of a new password to a third party, improve the security, a network, a network management device, a communication device, and use them It is to provide an automatic password change method.

A network according to the present invention is a network including a network management device and a plurality of communication devices managed by the network management device,
Each of the network management device and the communication device includes password creation means for creating a password of the communication device based on information obtained simultaneously in each of the network management device and the communication device,
In each of the network management device and the communication device, an independent and identical password is generated and stored.

A network management device according to the present invention is a network management device that manages a plurality of communication devices,
A password creating means for creating a password of the communication device based on information obtained simultaneously in the own device and the communication device;
In the own device and each of the communication devices, passwords having independent and identical contents are generated and stored.

A communication device according to the present invention is a communication device managed by a network management device,
A password creating means for creating a password of the own device based on information obtained simultaneously in each of the network management device and the own device;
In each of the network management device and the own device, passwords having independent and identical contents are generated and stored.

An automatic password change method according to the present invention is an automatic password change method used for a network including a network management device and a plurality of communication devices managed by the network management device,
On the side of each of the network management device and the communication device, comprising the step of creating a password for the communication device based on information obtained simultaneously in each of the network management device and the communication device,
In each of the network management device and the communication device, an independent and identical password is generated and stored.

  In other words, the password automatic change method of the present invention provides network management in a network in which a communication apparatus having a function of connecting to a network and communicating with each other and a network management apparatus that remotely operates these communication apparatuses via the network are connected. When operating each communication device from the device, the communication device has a function of authenticating the user using user information such as a user account and a password, and the password of the communication device is set between the network management device and the communication device. It relates to a method of automatically changing.

  In the automatic password change method of the present invention, in order to solve the above-described problem, both a network management device and a communication device managed by the network management device have broadcast receiving means for receiving broadcast data, and a network. Automatic time correction means for correcting the internal clock of each device to be always set to the same time, password generation condition storage means for storing password generation conditions in advance, and automatic generation of a new password from broadcast data based on the generation conditions Password information automatic generation means for generating / storing.

  In the password automatic change method of the present invention, when the password of the communication device managed by the network management device is changed, the password information automatic generation means in both the network management device and the communication device is stored in the password generation condition storage means. Based on the generation conditions, the password of the communication device can be directly transmitted / received via the network by automatically generating / storing the new password from the broadcast data received by the broadcast receiving means. The change is realized.

  The password generation condition storage means stores a new password generation trigger / generation date / time / broadcast reception channel / sampling interval / password length as generation conditions for automatically generating a new password.

  In both the network management device and the communication device, the internal clock of each device forming the network is always corrected to the same time by the automatic time correction means, and digital processing such as cable television or teletext is performed by the broadcast reception means. By receiving the broadcast data, it is possible for both devices to receive the same broadcast data at the same time.

  Accordingly, in the automatic password change method of the present invention, when changing or notifying that the password of the device connected via the network is changed, the content of the new password information is directly transmitted / received via the connected network. Instead, based on information obtained simultaneously by multiple devices such as broadcasting, each device independently generates a password for the communication device, so that the contents of the new password can be directly created on the network. It is possible to change the password without transmitting and receiving, and to improve security.

  Therefore, in the password automatic change method of the present invention, the password of the communication device is generated independently and with the same contents in each of the network management device and the communication device, so that the password information is directly stored on the network. Since it is not necessary to send / receive the contents, it is not necessary to send / receive the password information directly over the network when changing the password of the communication device, preventing leakage of the new password to a third party. Security can be improved.

  In the automatic password changing method of the present invention, the password can be automatically changed by each of the network management device and the communication device without going through the network administrator (person), so that the person can be managed / understood. Difficult, complex (meaningless / unrelated) and long passwords can be set, reducing the possibility of a password being clarified by an attack from a third party, and improving security .

  By adopting the configuration and operation as described below, the present invention can prevent leakage of a new password to a third party, and the effect of improving security can be obtained.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a network configuration according to an embodiment of the present invention. In FIG. 1, a network according to an embodiment of the present invention includes a network management device 1, communication devices 2-1 to 2 -n, and a broadcast distribution device 3 that are connected to each other via a public network 100. Yes.

  The communication devices 2-1 to 2-n are devices such as computers, servers, and routers that constitute a network, and the broadcast distribution device 3 is connected to the network management device 1 and the communication devices 2-1 to 2 through the broadcast network 101. Broadcast data is distributed to -n.

  The broadcast distribution device 3 may be connected to the same network as the public network 100 to which the network management device 1 and the communication devices 2-1 to 2-n are connected. Regardless, it is better to be connected via the broadcast network 101 using another network and medium.

  FIG. 2 is a block diagram showing a configuration of the network management apparatus 1 of FIG. In FIG. 2, the network management apparatus 1 includes a network management apparatus user information storage means (hereinafter referred to as user information storage means) 11, a user authentication means 12, a communication apparatus management storage means 13, a broadcast reception means 14, and a time. An automatic correction unit 15, a password generation condition storage unit 16, an automatic password generation unit 17, a communication device user information storage unit (hereinafter referred to as user information storage unit) 18, and a communication device connection unit 19. Yes.

  The user information storage unit 11 stores user account information, password information, and the like of the user who operates the network management device 1. The user authentication unit 12 authenticates a user who operates the network management apparatus 1. The communication device management storage unit 13 manages / stores configuration information of the communication devices 2-1 to 2-n. The broadcast receiving unit 14 receives information (broadcast data) distributed from the broadcast distribution device 3.

  The automatic time correction means 15 automatically corrects an internal clock (not shown) so that the time is the same among devices in the network. The password generation condition storage unit 16 stores a condition for generating a password possessed by each user of the communication devices 2-1 to 2 -n from the information received by the broadcast receiving unit 14.

  The automatic password generation means 17 automatically generates a password possessed by each user of the communication devices 2-1 to 2 -n from information received by the broadcast reception means 14 based on the conditions stored in the password generation condition storage means 16. The user information storage unit 18 stores the user account of the communication devices 2-1 to 2-n and the password generated by the password automatic generation unit 17. The communication device connection means 19 refers to the stored contents of the user information storage means 18 and connects to the communication devices 2-1 to 2-n.

  FIG. 3 is a block diagram showing the configuration of each of the communication devices 2-1 to 2-n in FIG. In FIG. 3, each of the communication devices 2-1 to 2-n has the same configuration, and thus each of the communication devices 2-1 to 2-n is represented as a communication device 2.

  In FIG. 3, the communication apparatus 2 includes a user information storage unit 21, a user authentication unit 22, a broadcast reception unit 23, an automatic time correction unit 24, a password generation condition storage unit 25, and an automatic password generation unit 26. Has been.

  The user information storage unit 21 stores user account information, password information, and the like of a user who operates the device. The user authentication means 22 authenticates a user who operates the own device. The broadcast receiving means 23 receives information (broadcast data) distributed from the broadcast distribution device 3. The automatic time correction means 24 automatically corrects an internal clock (not shown) held by the own device so that the devices in the network have the same time.

  The password generation condition storage unit 25 stores a condition for generating a password held by the user of the own apparatus from the information received by the broadcast receiving unit 23. Based on the conditions stored in the password generation condition storage unit 25, the automatic password generation unit 26 automatically generates a password held by the user of the device from the information received by the broadcast reception unit 23 and stores it in the user information storage unit 21. To do.

  Next, a method for automatically changing a password in a network according to an embodiment of the present invention will be described with reference to FIGS.

  When the network administrator operates the communication devices 2-1 to 2-n, the usage environment is limited to only remote operation for accessing the communication devices 2-1 to 2-n from the network management device 1. If the network administrator passes the authentication of the user of the network management device 1 by the network management device 1 by the generally used function of so-called “single sign-on”, the network management device 1 automatically communicates with the communication device 2-2. It is not necessary to perform user authentication again after the network administrator connects to the communication devices 2-1 to 2-n on behalf of the user authentication operation to 1-2-n.

  “Single sign-on” is when the network management apparatus 1 holds the user account information and password information of each of the communication apparatuses 2-1 to 2-n, and the network administrator connects to the communication apparatuses 2-1 to 2-n. The network management device 1 automatically performs user authentication operations on the communication devices 2-1 to 2-n on behalf of the network administrator.

  In this case, the password information possessed by each user of the communication devices 2-1 to 2-n only needs to match the recognition between the network management device 1 and each of the communication devices 2-1 to 2-n. In some cases, the network manager (person) does not need to manage / store the passwords of each of the communication devices 2-1 to 2-n, which are enormous.

  Further, the password can be automatically changed frequently between the network management device 1 and each of the communication devices 2-1 to 2-n, and generally it is difficult for a person to manage / store. However, it is possible to set a long password that is difficult for a third party to crack.

  FIG. 4 is a diagram showing a configuration example of each storage unit of the network management apparatus 1 shown in FIG. FIG. 4A shows a configuration example of the user information storage unit 11. In FIG. 4A, the user information storage unit 11 includes user accounts (“ope-1”, “ope-2”) and passwords (“passwd123”, “passwd456” as user information of users who operate the network management apparatus 1. )) Etc.

  FIG. 4B shows a configuration example of the communication device management storage unit 13. 4B, the communication device management storage means 13 includes device names (“equip-1”, “equip-2”) and connection addresses (“10.10”) of the communication devices 2-1 to 2-n connected to the network. 20.30.1 ”,“ 10.20.30.2 ”), operational status (“ in operation ”), and other basic configuration information of each of the communication devices 2-1 to 2-n forming the network. And remember.

  FIG. 4C shows a configuration example of the password generation condition storage unit 16. In FIG. 4C, the password generation condition storage means 16 is a condition for changing the password for each user who operates each of the communication devices 2-1 to 2-n (“password generation for device 2-1 / user # 1”). “Condition” and “Password generation condition for device 2-1 and user # 2”).

  FIG. 4D shows a configuration example of the user information storage means 18. In FIG. 4D, the user information storage means 18 stores a user account (“user-1”, “user-2”) and password (“KLsPwlkw7b7”) for each user who operates each of the communication devices 2-1 to 2-n. , “AiwdwU2ijwn83”).

  FIG. 5 is a diagram showing the configuration of each storage means in the communication apparatus 2 shown in FIG. FIG. 5A shows the configuration of the user information storage means 21. In FIG. 5 (a), the user information storage means 21 is a user account ("user-1", "user-2") or password ("KLsPwlkw7b7", "AiwdwU2ijwn83") as user information of the user who operates the device. Is remembered.

  FIG. 5B shows the configuration of the password generation condition storage unit 25. In FIG. 5B, the password generation condition storage means 25 is a condition for changing the password for each user who operates the device (“password generation condition for user # 1”, “password generation condition for user # 2”). Is remembered.

  FIG. 6 is a diagram showing a detailed configuration example of the password generation condition storage unit 16 in the network management apparatus 1 shown in FIG. In FIG. 6, the password generation condition storage unit 16 includes conditions [“generation opportunity (number of times / event)”, “generation date / time−1”, “ Generation date-2 "," generation date-3 "," reception channel "," sampling interval "," password length ", etc.].

  In the password generation condition storage means 16 for the apparatus 2-1, the condition of the user # 1 is "twice / day" as "generation opportunity (number of times / event)", and "daily-07" as "generation date-1". 0:00 "," Generation Date-2 "," Everyday-19:00 "," Receiving Channel "as" 3ch "," Sampling Interval "as" 10 octets ", and" Password Length "as" 12 characters " Has been.

  The conditions for user # 2 are “3 times / week” as “generation opportunity (count / event)”, “Monday-18: 00” as “generation date-1”, “Wednesday—as“ generation date-2 ” "09: 00", "Generation Date-3" as "Friday-20:00", "Reception Channel" as "12ch", "Sampling Interval" as "12 octets", and "Password Length" as "16 characters" It is remembered.

  As conditions for the user #n, “1 time / month” as “generation opportunity (number of times / event)”, “10 days-09: 00” as “generation date-1”, “2ch” as “reception channel”, “83 octets” as “sampling interval” and “29 characters” as “password length” are stored.

  FIG. 7 is a diagram showing a detailed configuration example of the password generation condition storage unit 25 in the communication device 2 shown in FIG. In FIG. 7, the password generation condition storage means 25 sets the conditions [“generation opportunity (number of times / event)”, “generation date-1”, “generation date-2”, “generation” for each user # 1 to #n of the own device. Date-3 "," reception channel "," sampling interval "," password length ", etc.].

  In the password generation condition storage unit 25, the conditions for the user # 1 are “2 times / day” as “generation opportunity (number of times / event)”, “daily-07: 0” as “generation date / time−1”, “generation” “Every day-19:00” is stored as “date and time-2”, “3ch” is stored as “reception channel”, “10 octets” is stored as “sampling interval”, and “12 characters” is stored as “password length”.

  The conditions for user # 2 are “3 times / week” as “generation opportunity (count / event)”, “Monday-18: 00” as “generation date-1”, “Wednesday—as“ generation date-2 ” "09: 00", "Generation Date-3" as "Friday-20:00", "Reception Channel" as "12ch", "Sampling Interval" as "12 octets", and "Password Length" as "16 characters" It is remembered.

  As conditions for the user #n, “1 time / month” as “generation opportunity (number of times / event)”, “10 days-09: 00” as “generation date-1”, “2ch” as “reception channel”, “83 octets” as “sampling interval” and “29 characters” as “password length” are stored.

  FIG. 8 is a flowchart showing an automatic password generation procedure according to an embodiment of the present invention, and FIG. 9 is a diagram showing a specific operation example of an automatic password generation procedure according to an embodiment of the present invention. A password automatic generation procedure according to an embodiment of the present invention will be described with reference to FIGS.

  In each of the network management device 1 and the communication devices 2-1 to 2-n, broadcast data having the same content distributed from the broadcast distribution device 3 is received by the broadcast receiving means 14 and 23 in the respective devices.

  Further, in each of the network management device 1 and the communication devices 2-1 to 2-n, for example, NTP (Network Time Protocol) or GPS (Global Positioning) generally used by the time automatic correction means 15 and 24 in each device. Using a time correction means such as (System), the internal clock of each device is corrected so that it is always the same time between the devices forming the network.

  Thereby, in each of the network management device 1 and the communication devices 2-1 to 2-n, the broadcast receiving means 14 and 23 in the respective devices receive the broadcast data having the same contents at the same time recognized by the respective devices. It becomes possible to receive.

  On the other hand, the generation conditions (see FIG. 6) stored in the password generation condition storage unit 16 in the network management apparatus 1 and the generation conditions (see FIG. 6) stored in the password generation condition storage unit 25 of each of the communication devices 2-1 to 2-n. 7) is set in advance by a network administrator (person), and generation conditions having the same contents are set for the same user of the corresponding communication device.

  In the password generation condition storage means 16 and 25, “generation opportunity”, “generation date / time”, “reception channel”, “sampling interval”, and “password length” are used as conditions for automatic generation. “Generation opportunity” indicates the period (day / week / month) and number of times (eg, three times a week) for changing to a new password, and “Generation date / time” indicates the date / time of change based on the generation opportunity (eg, Monday 18: “Receiving channel” generates a channel number for receiving broadcast data, “Sampling interval” generates a decimation interval for extracting characters for editing received broadcast data into a password, and “Password length” generates This is the condition for determining the number of characters in the password.

  Next, a password automatic generation procedure according to an embodiment of the present invention will be described with reference to FIGS.

  The password automatic generation means 17 and 26 refer to the “generation date and time” in the password generation condition storage means 16 and 25 (step S1 in FIG. 8). The password automatic generation means 17 and 26 identify whether the current time is changing to the “generation date / time” referred to (step S2 in FIG. 8). . In the example shown in FIG. 9, when the current time becomes “07:00”, the process proceeds to the next step S3.

  The password automatic generation means 17 and 26 repeat the above-described steps of referring to and identifying steps S1 and S2 if none of the users has a date of generation.

  The automatic password generation means 17 and 26 refer to the “reception channel” in the password generation condition storage means 16 and 25, and the broadcast reception means 14 and 23 receive the broadcast data of the designated channel (step S3 in FIG. 8). In the example shown in FIG. 9, (B) is the content of broadcast data received from “3ch” at “07: 0”.

  The password automatic generation means 17 and 26 remove unnecessary character data such as blank characters from the broadcast data received in the above-described step S3, and edit only to valid character data (step S4 in FIG. 8). In the example shown in FIG. 9, (C) shows the contents of the effective character data from which unnecessary character data is removed.

  The password automatic generation means 17 and 26 refer to the “sampling interval” and “password length” in the password generation condition storage means 16 and 25, and from the valid character data edited in the above step S4, the specified length is set every specified interval. Characters are extracted and edited as a new password (step S5 in FIG. 8). In the example shown in FIG. 9, the content of the new password is (D) in which character data of 12 characters is extracted from the valid character data of (C) and edited at intervals of 10 characters.

  The password automatic generation means 17, 26 stores the new password edited in step S5 in the user information storage means 18, 21 (step S5 in FIG. 8).

  According to the above procedure, in the present embodiment, when the new password is automatically changed, the network management device 1 and the communication devices 2-1 to 2 are notified without notifying the opposite password via the connected network. -N The new password can be stored in the user information storage means 18, 21 in each of both devices, and when the communication devices 2-1 to 2-n are subsequently operated from the network management device 1, they are newly changed. User authentication can be performed using the specified password.

  The basic configuration of one embodiment of the present invention is as described above. However, if the following points are devised, a stronger password can be generated and security can be further improved.

  In one embodiment of the present invention, each condition of “reception channel”, “sampling interval”, and “password length” is given to the user one by one. The condition may be changed every time.

  In one embodiment of the present invention, broadcast data based on character data is used as a base. However, editing may be performed based on audio or image data. Furthermore, in one embodiment of the present invention, characters are extracted from broadcast data at a simple sampling interval, but may be extracted as key information for encryption such as hash calculation and edited to a new password.

  As described above, in the present embodiment, the passwords of the communication devices 2-1 to 2-n are generated independently and with the same contents in each of the network management device 1 and the communication devices 2-1 to 2-n. This eliminates the need to send / receive the password information directly on the network, so when changing the password of the communication devices 2-1 to 2-n, the password information is sent / received directly on the network. This eliminates the need to do this, and prevents the leakage of a new password to a third party, thereby improving security.

  Also, in this embodiment, the password is automatically changed in each of the network management device 1 and the communication devices 2-1 to 2-n without going through the network administrator (person), so that It is possible to set a complicated (meaningless / unrelated) and long password that is difficult to manage / understand, thus reducing the possibility of a password being clarified by an attack from a third party and improving security. Can do.

  As an application example of the present invention, in a network to which a large number of communication devices such as computers, servers, routers and the like are connected, a device that constitutes a network in which a specific network manager manages a large number of communication devices from a specific network management device It is effective against.

It is a block diagram which shows the structure of the network by one Example of this invention. It is a block diagram which shows the structure of the network management apparatus of FIG. It is a block diagram which shows the structure of each communication apparatus of FIG. (A) is a diagram showing a configuration example of the user information storage means in FIG. 2, (b) is a diagram showing a configuration example of the communication device management storage means in FIG. 2, (c) is a diagram of the password generation condition storage means in FIG. The figure which shows a structural example, (d) is a figure which shows the structural example of the user information storage means of FIG. (A) is a figure which shows the structural example of the user information storage means of FIG. 3, (b) is a figure which shows the structural example of the password production | generation condition storage means of FIG. It is a figure which shows the detailed structural example of the password generation condition memory | storage means in the network management apparatus shown in FIG. It is a figure which shows the detailed structural example of the password generation condition memory | storage means in the communication apparatus shown in FIG. It is a flowchart which shows the password automatic generation procedure by one Example of this invention. It is a figure which shows the specific operation example of the password automatic generation procedure by one Example of this invention.

Explanation of symbols

1 Network management device 1
2,2-1 to 2-n communication device
3 Broadcast distribution equipment
11 Network management device user information storage means
12, 22 User authentication means
13 Communication device management storage means
14, 23 Broadcast receiving means
15, 24 Automatic time correction means
16, 25 Password generation condition storage means
17, 26 Automatic password generation means
18 Communication device user information storage means
19 Communication device connection means
21 User information storage means
100 public network
101 Broadcast network

Claims (16)

A network including a network management device and a plurality of communication devices managed by the network management device,
Each of the network management device and the communication device has password creation means for creating a password of the communication device based on information obtained simultaneously in each of the network management device and the communication device,
A network characterized in that a password having an independent and identical content is generated and stored in each of the network management device and the communication device.   The network according to claim 1, wherein the communication device is at least one of a computer, a server device, and a router device. Password generation condition storage means for storing generation conditions for generating the password is included in each of the network management device and the communication device,
2. The password generation unit generates the password based on information obtained simultaneously in each of the network management device and the communication device and a generation condition stored in the password generation condition storage unit. Or the network according to claim 2.   The network according to claim 3, wherein the generation condition includes a generation opportunity including a number of times and a period, a generation date and time, a reception channel, a sampling interval, and a password length. A network management device for managing a plurality of communication devices,
Having a password creating means for creating a password of the communication device based on information obtained simultaneously in the own device and the communication device;
A network management device characterized in that a password having an independent and identical content is generated and stored in each of the device itself and the communication device.   The network management device according to claim 5, wherein the communication device is at least one of a computer, a server device, and a router device. Password generation condition storage means for storing generation conditions for generating the password,
6. The password generation unit according to claim 5, wherein the password generation unit generates the password based on information obtained simultaneously in each of the device and the communication device and a generation condition stored in the password generation condition storage unit. Item 7. The network management device according to Item 6.   8. The network management apparatus according to claim 7, wherein the generation condition includes a generation opportunity including a number of times and a period, a generation date and time, a reception channel, a sampling interval, and a password length. A communication device managed by a network management device,
Having a password creating means for creating a password of the own device based on information obtained simultaneously in each of the network management device and the own device;
A communication apparatus, wherein each of the network management apparatus and its own apparatus generates and stores a password having independent and identical contents.   The communication device according to claim 9, wherein the communication device is at least one of a computer, a server device, and a router device. Password generation condition storage means for storing generation conditions for generating the password,
10. The password generation unit generates the password based on information obtained simultaneously in each of the network management device and the own device and a generation condition stored in the password generation condition storage unit. The communication apparatus according to claim 10.   12. The communication apparatus according to claim 11, wherein the generation condition includes a generation opportunity including a number of times and a period, a generation date and time, a reception channel, a sampling interval, and a password length. A password automatic change method used for a network including a network management device and a plurality of communication devices managed by the network management device,
On the side of each of the network management device and the communication device, the step of creating a password for the communication device based on information obtained simultaneously in each of the network management device and the communication device,
A password automatic change method, wherein each of the network management device and the communication device generates and stores a password having the same and independent contents.   14. The password automatic change method according to claim 13, wherein the communication device is at least one of a computer, a server device, and a router device.   The step of creating the password includes a password for storing information obtained simultaneously in each of the network management device and the communication device, and a generation condition provided in each of the network management device and the communication device and for generating the password 15. The password automatic change method according to claim 13, wherein the password is generated based on a generation condition of the generation condition storage means. 16. The password automatic change method according to claim 15, wherein the generation condition includes a generation opportunity including a number of times and a period, a generation date and time, a reception channel, a sampling interval, and a password length.

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