JP2011259134A - Management method of terminal equipment, terminal equipment, program and network system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology by which connection of unauthorized terminal equipment can be detected regardless of a server operation state in a network system.SOLUTION: A shared data key is given to two or more pieces of authorized terminal equipment. First terminal equipment, which is authorized terminal equipment, transmits data encrypted with the data key via a network system or third terminal equipment, which is one piece of terminal equipment other than the two or more pieces of terminal equipment connected to the network system, transmits data D. When second terminal equipment, which is authorized terminal equipment, receives the encrypted data or the data D, the second terminal equipment decrypts the received data using the data key of the own storage device. Whether the third terminal equipment is authorized terminal equipment or not is determined according to the decryption result of the encrypted data.

Description

  The present invention relates to detection of unauthorized terminal devices in a network system and protection of authorized terminal devices from unauthorized terminal devices.

  It is not preferable from the viewpoint of information security to illegally connect a terminal device to a network system and to illegally access other terminal devices or servers in the network system. When an unauthorized terminal device is connected to a network, it is required to promptly detect and take appropriate measures.

  Some conventional network systems detect, for example, the presence of unauthorized terminal devices by monitoring a communication state in the network system with a server. For example, Patent Document 1 discloses a technique for detecting an unauthorized terminal by authenticating a terminal using a terminal key stored in advance in the terminal. Hereinafter, in this specification, this type of server is referred to as a monitoring server.

  According to such a conventional technique, for the purpose of detecting an unauthorized terminal device in the monitoring server, when a failure occurs in the monitoring server, such as when a failure occurs in the monitoring server, the unauthorized terminal device can be detected. Disappear.

JP 2005-228299 A

  As one method for preparing for the occurrence of a malfunction in the monitoring server, redundancy of the monitoring server can be considered. That is, when a normal operation server and a backup server are provided as monitoring servers, only the normal operation server monitoring function is normally operated, the backup server monitoring function is stopped, and a problem occurs in the normal operation server. Transfer the monitoring function from the normal operation server to the backup server. This can prevent a situation in which the monitoring function is not operating in the network system.

  However, according to such redundancy of the monitoring server, it is necessary to manage both the normal operation server and the backup server, and there is a problem that the management cost of the system increases.

  Further, according to the redundancy of the monitoring server, the monitoring function does not work in the network system while the monitoring function is transferred from the normal operation server to the backup server. For this reason, unauthorized terminal devices connected to the network system during the transfer of functions, illegal access to authorized terminal devices and servers, impersonation of authorized terminal devices, data tampering, information leakage, etc. There is a concern that

  The present invention has been made in view of such a situation, and a problem to be solved by the present invention is to provide a technology capable of detecting connection of an unauthorized terminal device in a network system regardless of the operation status of a server. It is to be.

  In order to solve the above-described problems, the present invention provides the following terminal device, program, and terminal device management method.

  As one aspect, the present invention includes a plurality of servers each belonging to a different hierarchy, and a first identifier for identifying servers belonging to the same hierarchy is assigned to each of the plurality of servers, In a network system in which a plurality of terminal devices are connected to each of the servers, when a seed is given in advance as a data key of the highest server, the terminal device belongs to and Data that is one encryption key generated by inputting the identifier of 1 and the data key of the server belonging to the level one higher than the server as viewed from the terminal device into a secret function to a third party A storage device for storing a key, and a terminal device of the plurality of terminal devices, wherein a first terminal device other than the terminal device stores the storage device of the first terminal device The encrypted data transmitted through the network system is generated based on the data key or the data key by encrypting using the data key stored in the network or the encryption key generated based on the data key. A terminal comprising: decryption means for decrypting using the encrypted key; and determination means for determining that the first terminal device is a legitimate terminal device in accordance with a decryption result of the encrypted data. Provide equipment.

Moreover, the present invention includes, as one aspect thereof, a plurality of servers each belonging to a different hierarchy, and a first identifier for identifying each other of servers belonging to the same hierarchy is assigned to each of the plurality of servers, In a network system in which a plurality of terminal devices are connected to each lowermost server, when a seed is given in advance as a data key of the highest server, the terminal device belongs and belongs to one of the above layers And a single encryption key generated by inputting the data key of the server belonging to the level one higher than the server as viewed from the terminal device into a secret function to a third party. A storage procedure for storing a data key in a storage device;
A terminal device of the plurality of terminal devices, wherein a first terminal device other than the terminal device encrypts the data using the data key stored in the storage device of the first terminal device; A first decryption procedure for decrypting encrypted data transmitted via the system;
A first determination procedure for determining that the first terminal device is a legitimate terminal device according to a decryption result of the encrypted data;
A program for causing a computer to execute the program is provided.

Moreover, the present invention includes, as one aspect thereof, a plurality of servers each belonging to a different hierarchy, and a first identifier for identifying each other of servers belonging to the same hierarchy is assigned to each of the plurality of servers, In a network system in which a plurality of terminal devices are connected to each lowermost server, when a seed is given in advance as a data key of the highest server, the terminal device belongs and belongs to one of the above layers And a single encryption key generated by inputting the data key of the server belonging to the level one higher than the server as viewed from the terminal device into a secret function to a third party. A storage step of storing a data key in each storage device of the plurality of terminal devices;
A first terminal device that is one terminal device among the plurality of terminal devices uses the network system to encrypt data that is encrypted using the data key or an encryption key generated based on the data key. A transmission stage to transmit via,
A receiving step in which a second terminal device that is one terminal device of the plurality of terminal devices and is a terminal device other than the first terminal device receives the encrypted data;
A decryption step in which the second terminal device decrypts the encrypted data using the data key stored in its storage device or an encryption key generated based on the data key;
A terminal device management method comprising: a determination step in which the second terminal device determines that the first terminal device is a legitimate terminal device according to a decryption result of the encrypted data. provide.

  According to the present invention, the determination as to whether or not the terminal device is legitimate is performed by another terminal device to which the same data key as that terminal device is assigned in advance. For this reason, it is possible to detect an unauthorized terminal device without providing a monitoring server for detecting the unauthorized terminal device, or even if it is provided, regardless of the operation state. At this time, no additional device such as a backup monitoring server is required.

1 is a block diagram of a network system 100 according to an embodiment of the present invention. 3 is a diagram for describing terminal devices belonging to groups 1-1-4 to 1-1-7 of the network system 100. FIG. It is a block diagram for demonstrating the structure of the terminal devices 1-2-1-1-2-4. It is a figure for demonstrating the generation method of a data key. It is a figure for demonstrating operation | movement of the network system 100 in Example 1 of this invention. It is a functional block diagram of the authentication part 1-2-1-1. It is a functional block diagram of monitoring part 1-2-1-2. It is a figure for demonstrating operation | movement of the network system 100 in Example 2 of this invention. It is a functional block diagram of the authentication part 1-2-1-1 in Example 3 of this invention. It is a functional block diagram of the monitoring part 1-2-1-2 in Example 3 of this invention.

  A network system 100 according to an embodiment of the present invention will be described with reference to FIG. The network system 100 is a computer network that transmits data by designating a server or a terminal device by address information such as a MAC (Media Access Control) address and an IP (Internet Protocol) address.

  [Center] [Head office] [Branch office] [Group] indicate attributes. An organization configured by a network connecting these attributes has a pyramid structure in the order of attributes of [Headquarters], [Branch offices], and [Groups] with [Center] at the top.

  Reference numeral 1-1-1 denotes a center server, which manages an organization configured by a network, that is, a server of each attribute under the network and terminal devices belonging to each [group]. Reference numerals 1-1-2 and 1-1-3 denote different head office servers, which manage branch office servers under the server and terminal devices in the [group]. 1-1-4 to 1-1-7 represent different branch office servers, and manage terminal devices belonging to [Group] under the server. 1-1-8 to 1-1-15 represent groups. A group consists of a plurality of terminal devices.

A different value is assigned to each of the head office servers 1-1-2 and 1-1-3 as the attribute value ID _x . Attribute ID _x headquarters server 1-1-2 is 001, the attribute value ID _x headquarters server 1-1-3 is 002. An attribute value ID _y is assigned to each of the branch office servers 1-1-4 to 1-1-7. The attribute values ID _y of the branch office servers 1-1-4 to 1-1-7 are 001, 002, 001, and 002, respectively. The attribute values ID _y of branch office servers under the same head office server are different. Further, similarly, an attribute value ID _z is assigned to each group. The attribute values ID _z of the groups 1-1-8 to 1-1-15 are 001, 002, 001, 002, 001, 002, 001, and 002, respectively. The attribute values ID _{z of the} groups under the same branch server are different. The attribute value may be known to a third party, but is preferably kept secret.

Using the attribute values ID _x , ID _y , and ID _z thus determined, the groups 1-1-8 to 1-1-15 can be uniquely represented. That is, each group of the network system 100 is a set of the attribute value ID _z of the group, the attribute value ID _y of the branch office server to which the group belongs, and the attribute value ID _x of the head office server to which the branch server belongs ( ID _x , ID _y , ID _z ). A set of attribute values (ID _x , ID _y , ID _z ) indicating the group is assigned to all terminal devices belonging to a certain group as attribute values of the terminal device. For example, the attribute values (ID _x , ID _y , ID _z ) of the terminal devices belonging to the group 1-1-8 are (001, 001, 001). Further, the attribute values (ID _x , ID _y , ID _z ) of the terminal devices belonging to the group 1-1-12 are (002, 001, 001). In FIG. 1, the attribute values of the terminal devices belonging to each group are shown below each group.

  In the following, in the pyramid structure as shown in FIG. 1, when the server B is directly under a certain server A, the server A is called a parent server of the server B, and the server B is called a child server of the server A. Server C, which is a child server of server B, is called a grandchild server of server A. It is also noted that servers B and C are under server A, and server A is above servers B and C. If the server / terminal devices are in a parent-child, grandfather-grandchild, great-grandfather-great-grandchild relationship, they shall be marked as having a kinship relationship. For example, the branch office servers 1-1-8 to 1-1-15 are grandchild servers of the center server 1-1-1. The child servers of the head office server 1-1-2 are branch office servers 1-1-4 and 1-1-5. When viewed from the terminal devices 1-2-1 to 1-2-4, the branch office server 1-1-4 is the parent server, the head office server 1-1-2 is the grandfather server, and the center server 1-1-1 is the great grandfather server. It is. The terminal device 1-2-1, the branch office server 1-1-4, the head office server 1-1-2, and the center server 1-1-1 have a kinship relationship.

With reference to FIG. 2, terminal devices belonging to each group or constituting each group will be described. As described above, terminal devices belonging to the same group are assigned the same attribute values (ID _x , ID _y , ID _z ), but each terminal device has a unique ID. The unique ID is a unique identifier, for example, a vendor name concatenated with a production number, specifically, a MAC (Media Access Control) address. As shown in FIG. 2, in the network system 100, four terminal devices belong to each group. A unique ID of the terminal device is shown in parentheses () immediately below each terminal device, and consists of a letter N and a three-digit number. Under the four unique IDs of the four terminal devices, attribute values of these terminal devices are described. Taking the group 1-1-8 as an example, the unique IDs of the four terminal devices 1-2-1, 1-2-2, 1-2-3, 1-2-4 belonging to this group are N001, respectively. , N002, N003, and N004, which are different values, but the attribute values (ID _x , ID _y , ID _z ) of these four terminal devices are (001, 001, 001) and are common to all four devices. It is.

  The configuration of the terminal devices 1-2-1 to 1-232 will be described. The configuration of these terminal devices is basically the same, and here, the terminal devices 1-2-1 to 1-2-4 constituting the group 1-1-8 are taken as an example. As shown in FIG. 3, all the terminal devices 1-2-1 to 1-2-4 are connected to the branch office server 1-1-4 via a hub 1-4-1. Each terminal device includes an authentication unit and a monitoring unit.

  The authentication unit authenticates a server that is a communication partner. Also, the encrypted device control command transmitted from another terminal device in the same group is decrypted and passed to the device control unit 1-5-17. Details of the authentication unit will be described later with reference to FIG.

  When the monitoring unit monitors communication performed by the other terminal device belonging to the same group with the server and detects that the terminal device is transmitted from an unauthorized terminal device, the monitoring unit functions to the other terminal device belonging to the same group. An instruction to send a control command is given. Details of the monitoring unit will be described later with reference to FIG.

Each terminal device includes a storage device that stores a unique ID of the terminal device. This storage device is, for example, a flash ROM with a built-in network interface card. Furthermore, a storage device is provided that stores attribute values (ID _x , ID _y , ID _z ) given in advance to the terminal device, a data key, an authentication key, and a transmission authority table to be described later. This storage device is a main storage device or auxiliary storage device of a terminal device as a computer, more specifically, a semiconductor memory device or a fixed magnetic disk recording device. For example, the terminal device 1-2-1 includes an authentication unit 1-2-1-1, a monitoring unit 1-2-1-2, a storage device 1-2-1-3 that stores N001 as a unique ID, and an attribute value (001, 001, 001) is stored, and further, a storage device 1-2-1-4 for storing ds _xyz , df _xy , dc _x , s as data keys to be described later, and a storage device 1 for storing a transmission authority table 2-1-5. Here, the storage devices that store the unique ID, the attribute value, the data key, the authentication key, and the transmission authority table have been described as separate storage devices, but may be different storage areas of the same storage device. The terminal device 1-2-1 further includes an arithmetic device as an element (not shown), and may include an input device such as a keyboard and a mouse and an output device such as a display as necessary. The terminal devices 1-2-2 to 1-2-4 have the same configuration, and the same applies to the terminal devices of other groups 1-1-9 to 1-1-15.

  The data key will be described with reference to FIG. The data key is a common key encryption key used when performing encrypted communication between the terminal device and the server.

The center server 1-1-1 stores the attribute value ID _x of each subordinate head office server, the attribute value ID _y of each branch server, and the attribute value ID _z of each group in a storage device in advance. The attribute value of the terminal device of each group is a set of the attribute value of the head office server, branch office server, and group to which the terminal device belongs, and can be easily obtained. It may be obtained or may be obtained in advance from the attribute value of the server to which it belongs and stored in the storage device.

The head office servers 1-1-2 and 1-1-3 store the attribute value ID _x assigned to them, the attribute value ID _y of the branch server under their control, and the attribute value ID _{z of the} group in the storage device in advance. is doing. For example, the head office server 1-1-2 has its own attribute value ID _x = 001, the attribute value ID _y = 001 of the branch office server 1-1-4, the attribute value ID _y = 002 of the branch office server 1-1-5, Group 1-1-8 attribute value ID _z = 001, Group 1-1-9 attribute value ID _z = 002, Group 1-1-10 attribute value ID _z = 001, Group 1-1-11 attribute The value ID _z = 002 is stored in the storage device.

Branch server 1-1-4～1-1-7 has an attribute value ID _y assigned to itself, are stored in advance in the storage device attribute value ID _z group working under the. For example, the branch server 1-1-4 stores its own attribute value ID _y = 001, attribute value ID _z = 001 of group 1-1-8, and attribute value ID _z = 002 of group 1-1-9. ing.

  In this way, each server stores its own attribute value and the attribute values of the servers under it in the storage device. In this state, each server receives its own data key from its parent server, generates a data key of its child server by performing a hash operation on the concatenation of its own data key and the attribute value of the child server, The data is transmitted to the child server and the terminal device under its control. The hash function used for the hash calculation and the data key generated as a result of the hash calculation are particularly confidential to a third party. The data key is transmitted using another encryption key that can be decrypted only by the corresponding server / terminal device, using another encryption technology, and only the corresponding server / terminal device is used as the destination. It is preferable. Alternatively, instead of encrypting and transmitting the data key, the data key may be stored in a recording medium and read by the child server.

  Further, each server generates a grandchild data key as necessary or in advance. That is, the data key of the grandchild server is generated by performing a hash operation on the concatenation of the data key of the generated child server and the attribute value of a grandchild server. The data key of the grandchild server does not need to be transmitted because the child server generates and transmits it. In the present embodiment, there is no descendant server below the great-grandchild, but if it exists, it is obtained in the same manner as necessary or in advance.

Specifically, first, the administrator of the network system 100 inputs the data key of the center server 1-1-1, that is, the secret seed s, to the center server 1-1-1. The center server 1-1-1 transmits the secret seed s to all the terminal devices 1-2-1 to 1-232. The secret seed is kept secret to third parties as its name suggests. The center server 1-1-1 generates a data key dc _x of the head office server 1-1-2 by performing a hash operation on the concatenation of the secret seed s and the attribute value ID _x = 001, The data is transmitted to the server 1-1-2 and the terminal devices 1-2-1 to 1-2-16. Similarly, the center server 1-1-1 generates the data key dc _x of the head office server 1-1-3 by performing a hash operation on the concatenation of the secret seed s and the attribute value IDx = 002, and the head office The data is transmitted to the server 1-1-3 and the terminal devices 1-2-17 to 1-232. Further, the center server 1-1-1 hashes the data key dc _x of a certain head office server and the attribute value ID _y of a branch office server that is a child server of the head office server as necessary or previously hashed. By calculating, the data key df _xy of the branch office server is generated. Similarly, the center server 1-1-1 generates a group data key ds _xyz as necessary or in advance.

Each head office server generates a data key df _xy of the branch server by performing a hash operation on the concatenation of its own data key dc _x received from the center server and the attribute value ID _y of the subordinate branch server. , Send it to that branch server. Further, a data key ds _xyz of a group having a grandchild relationship is generated as necessary or in advance. For example, the head office server 1-1-2 generates the data key df _xy of the branch server 1-1-4 from its own data key dc _x and the attribute value ID _y = 001 of the branch server 1-1-4, It transmits to the branch office server 1-1-4 and the terminal devices 1-2-1 to 1-2-8.

Each branch server performs a hash operation on the concatenation of its own data key df _xy received from the head office server as the parent server and the attribute value ID _z of the subordinate group, thereby obtaining the data key ds _{xyz of the} group. Generated and transmitted to each terminal device belonging to the group.

When the data keys s, dc _x , df _xy , and ds _xyz are distributed to the terminal devices in this way, each terminal device has its own group data key, its own parent server (branch server), grandfather server (head office server). ), Have the data key of great-grandfather server (center server). Each server can use its own data key and the data key of the server under its control. At this time, whether or not the encrypted information encrypted using the data keys s, dc _x , df _xy , and ds _xyz in a certain terminal device can be decrypted is as shown in Table 1 below.

As shown in Table 1, the ciphers using the data keys ds _xyz and df _xy can be decrypted by all the server / terminal devices that are related to each other. The encryption using the data key dc _x can be decrypted by the terminal device, the head office server, and the center server that are in a relative relationship with each other. Encryption using the data key (secret seed) s can be decrypted by the terminal device and the center server of the same group. Decryption cannot be performed by servers that are not in a relative relationship with each other or terminal devices of different groups. Note that the terminal devices of the same group have a relative relationship with each other. Since all the data keys are common key encryption keys, whether or not the encrypted information encrypted by another terminal device or server in a certain terminal device can be decrypted is as shown in Table 1.

  That is, by selecting a data key used for encryption, a terminal device and a server that can be decrypted can be specified to some extent. Encrypted information that can be decrypted by a server can always be decrypted by a higher-order server that is in a kinship relationship with that server, but may not be decrypted by a lower-order server even if it is in a kinship relationship with that server. Absent. This is referred to as a higher server having a higher reception authority than a lower server, or conversely, a lower server has a lower reception authority than a higher server. In addition, the head office server and the branch office server that are not related to each other cannot be decrypted.

  In FIG. 4, the status information [status] encrypted by the terminal device using the data key is transmitted to the center server via the branch office server and the head office server that are related to each other. By appropriately selecting the data key to be used for encryption at the terminal device, it cannot be decrypted by a lower server that does not have the desired reception authority, and the upper server that has a reception authority higher than the desired reception authority, and The terminal device belonging to the same group can transmit encrypted status information [status] so that it can be decrypted.

As described above, the reception authority is an authority given to each server with respect to data transmission in the direction from the terminal device to the server, and is realized using a hierarchical encryption key. On the other hand, transmission authority is given to each server regarding reverse communication, that is, command transmission in the direction from the server to the terminal device. When transmitting a command from the server to the terminal device, the server encrypts the command with the data key ds _{xyz of the} group to which the terminal device belongs and transmits the command to the terminal device. This command includes the terminal device, and can be decrypted by all servers and terminal devices that have a relative relationship with the terminal device, but whether or not the terminal device that is the target of the command executes the command, The terminal device determines based on the transmission authority predetermined for each attribute of the transmission source server.

  In order to realize the transmission authority, the terminal device stores a transmission authority table in the storage device. The transmission authority table is a table that stores associations between commands, servers that transmitted the commands, and whether or not the commands can be executed. The terminal device refers to the transmission authority table stored in advance in its own storage device, determines whether or not the command transmission source server has the authority to transmit the command, and executes the command only if it has . An example of the transmission authority table is shown in Table 2. The reception authority and transmission authority are collectively referred to as access authority.

  For example, in Table 2, the center server is the only server that has the authority to transmit command command1, that is, the authority to request the terminal device to execute command command1. On the other hand, only the center server and the head office server that is in a kinship relationship with the counterpart terminal device have the authority to send the command auth_multi_x. There is no transmission authority for the head office server and branch office servers that are not related to each other.

A server can be identified based on a value obtained by hashing the attribute of the server. For example, when the head office server 1-1-2 sends a command command to the terminal device 1-2-1, the attribute ID _x of the head office server 1-1-2 is hashed to generate the value ac _x. In addition, a command [command], a counter value count, and a command to be executed by the terminal device by generating a MAC (ac _x , count) by performing MAC (Message Authentication Code) operation on the value ac _x using the counter value count as a key. Concatenated MAC operation values MAC (ac _x , count) [command] || (count || MAC (ac _x , count))
Is transmitted from the head office server 1-1-2 to the terminal device 1-2-1. Receiving this, the terminal device 1-2-1 generates the value ac _x and the MAC operation value MAC (ac _x , count) from the known attribute ID _x of the head office server 1-1-2 using the count value count as a key. When the MAC operation value is compared with the MAC operation value received in connection with the command [command], and the two match, the terminal device 1-2-1 sends the command [command] to the head office server 1. Authenticate that it is -1-2. Subsequently, the terminal device 1-2-1 refers to the transmission authority table 1-2-1-5 and determines whether or not the head office server 1-1-2 has an authority to transmit the command [command].

In FIG. 4, when the access authority of each server is compared, the access authority is higher in the order of the center server, the head office server, and the branch office server. When transmitting encrypted information encrypted using a data key from a terminal device to each server, it can be decrypted by a lower server that can be decrypted by the destination server and does not need to be decrypted. It is preferable to use an impossible data key. For example, since the head office server has data keys dc _x , df _xy , and ds _xyz , the encryption information encrypted with any of these data keys has the data key necessary for decryption, If the information does not need to be notified to the branch office server, it is preferable to encrypt it using the data key dc _x so that it cannot be decrypted by the branch office server.

  Since the terminal devices belonging to the same group have the same attribute value, the held data key is also the same. Therefore, when a terminal device generates encryption information using a data key, other terminal devices belonging to the same group as the terminal device have a data key necessary for decrypting the encryption information. become.

Returning to FIG. 1, the four data keys s, dc _x , df _xy , and ds _xyz that each terminal device has vary depending on the attribute values of the terminal device, but the attribute values of the terminal devices belonging to the same group are the same. is there. The network system 100 as a whole has eight groups of data keys s, dc _x , df _xy , and ds _xyz corresponding to the eight groups 1-1-8 to 1-1-15. Assume that encryption information is generated using one of the data keys held by a certain terminal device belonging to a certain group and is transmitted to one of the servers. At this time, since all other terminal devices belonging to the same group have the same data key set as the source terminal device, any of the four data keys used for encryption can be used. Therefore, it always has a data key necessary for decrypting the encrypted information.

For example, in FIG. 3, the terminal device 1-2-1 generates encryption information using the data key dc _x stored in its own storage device 1-2-1-4, and the head office server 1-1-2. Terminal device 1-2-2 belonging to the same group as the terminal device 1-2-1 stores the same data key dc _x in its own storage device 1-2-2-4. . The same applies to the terminal devices 1-2-3 and 1-2-4.

  Using this, in the network system 100, when a certain terminal device A performs encrypted communication using a data key, the monitoring unit of another terminal device B that belongs to the same group as the terminal device A and has the same data key Receives the encrypted communication and attempts to decrypt it. Then, according to the decryption result, the monitoring unit of the terminal device B determines whether the terminal device A is a legitimate terminal device or an unauthorized terminal device impersonating the legitimate terminal device and connected to the network system 100. Determine. An unauthorized terminal device is detected based on the determination result. When an unauthorized terminal device is detected, the monitoring unit of the terminal device B sends a device control command for urging to stop part or all of the functions to other terminal devices in the group and controls the device control of the terminal device B. To stop a part or all of the functions of the terminal device B.

  With reference to FIG. 5, in the network system 100, detection of an unauthorized terminal device performed when a malfunction occurs in the operation of the host server of the terminal device, and the response at that time will be described as a first embodiment. Even when the host server of the terminal device becomes inoperable due to a malfunction, the terminal devices having the same authentication key monitor each other to ensure a certain level of security.

In the same configuration as FIG. 1, three attributes [head office]: ID _x , [branch office]: ID _y , and [group]: ID _z are defined below [center]. [Center], [Head office], and [Branch office] respectively correspond to servers, that is, center server 1-1-1, head office servers 1-1-2, 1-1-3, and branch office servers 1-1-4 to 1. -1-7 exists. [Group] does not have a corresponding server. Instead, a sub-network is constructed with a communication device such as a gateway, and an attribute value ID _z of [Group] is assigned to each sub-network. Therefore, the branch office server is responsible for the attribute ID _z of [Group].

  The center server 1-1-1, head office servers 1-1-2, 1-1-3, branch office servers 1-1-4 to 1-1-7, and group servers 1-1-8 to 1-1-15 Assume that the following information is stored in advance in each storage device. However, as described above, information on the group is held by the branch office server.

Authentication key refers server or terminal device attribute value _{(ID x, ID y, ID} z) a set of keys corresponding to _{(ac x, af y, as} z) a. Also refers to exclusive OR of these a set of elements _ac x _keys, af _y, as _z. For example, when a value y obtained by hashing x is expressed by y = H (x), ac _x = H (IDx), af _y = H (IDy), and as _z = H (IDz). In particular, an authentication key with ID _y = 000 is af0, and an authentication key with ID _z = 000 is as0. In particular, an authentication key with ID _y = 000 is af0, and an authentication key with ID _z = 000 is as0. i is a unique ID of the terminal device.

・ Center server 1-1-1
Secret seed: s
Authentication _{key: ac x, af y, as} z
The unique numbers N001 to N032 of the terminal devices 1-2-1 to 1-232
Attribute values IDx, IDy, IDz, (001, 001, 001), (001, 001, 002), (001, 002, 001), (001, 002) of the terminal devices 1-2-1 to 1-232. , 002), (002, 001, 001), (002, 001, 002), (002, 002, 001), (002, 002, 002)
・ Head office server 1-1-2, 1-1-3
Data key dc _x
Authentication key: ac _z , af ₀ , as ₀
・ Branch server 1-1-4 to 1-1-7
Data key df _xy
Authentication _{key: ac x, af y, as} 0
Group 1-1-8 to 1-1-15
Data key ds _xyz
Authentication _{key: ac x, af y, as} z
・ Terminal equipment 1-2-1 to 1-232
Secret seed: s
Data keys dc _x , df _xy , ds _xyz
Authentication _{key: ac x, af y, as} z
Own unique number Own attribute value IDx, IDy, IDz

The sequence of this embodiment is divided into the following four.
(1) Authentication of each attribute and attribute IDx, IDy, IDz in the terminal device (2) Communication disconnection due to a branch server failure (3) Return of the authentication result in the terminal device (4) Function at the time of abnormality detection by the monitoring unit This will be described with reference to FIG.

(1) Authentication of attributes IDx, IDy, and IDz in each attribute and terminal device As shown in Sequences 2-1, 2-4, and 2-7, the attributes of the headquarters for all headquarter servers, branch servers, and terminal devices to authenticate ID _x indicating the obtained to perform the next execution formula. In this embodiment, the center server 1-1-1 transmits an authentication command.

[Auth_mlti_x] || (count || MAC (ac _x , count)
Here, [auth_mlti_x] indicates an execution command for requesting authentication of ID _x . “count” indicates a counter value incremented by one. In this state, multicast transmission is performed without encrypting [auth_mlti_x] and below.

[Auth_mlti_x] The following shows an execution expression for authenticating whether or not the attribute ID _{x of the} transmission destination is correct. That is, in each of the server and the terminal device, the MAC value of the count is calculated with the authentication key ac _x of the attribute ID _x held by itself, and the same MAC value is obtained, that is, the head office server, the branch server, and the terminal device hold. to make sure that the authentication key ac _x, and an authentication key ac _x the center server to hold matches.

Next, as shown in sequence 2-1, 2-4, 2-7, the center server 1-1-1 has ID _y indicating the attribute of the branch office for all head office servers, branch office servers, and terminal devices. In order to perform authentication, it asks to execute the following execution formula.

[Auth_mlti_y] || (count || MAC (af _y , count)
Here, [auth_mlti_y] indicates an execution command for requesting authentication of ID _y . In this state, multicast transmission is performed without encrypting [auth_mlti_y] and below.

[Auth_mlti_y] The following shows an execution formula for authenticating whether or not the destination attribute ID _y is correct. That is, in each server or terminal device, and calculates the authentication key af _y attribute ID _y which holds the MAC value of the count itself, be the same MAC value, i.e., the head office server, branch server, the terminal device holds to make sure that the authentication key af _y, and the authentication key af _y the center server to hold matches.

Next, as shown in sequences 2-3, 2-6, and 2-9, the center server 1-1-1 has the ID _z indicating the group attribute for all head office servers, branch office servers, and terminal devices. In order to perform authentication, it asks to execute the following execution formula.

[Auth_mlti_z] || (count || MAC (as _z , count)
[Auth_mlti_z] indicates an execution command that requests authentication of ID _z . In this state, multicast transmission is performed without encrypting the data below [auth_mlti_z].

[Auth_mlti_z] The following shows an execution formula for authenticating whether or not the attribute IDz of the transmission destination is correct. That is, in each of the server and the terminal device, the MAC value of the count is calculated with the authentication key as _z of the attribute ID _z held by itself, and the same MAC value is obtained, that is, the head office server, the branch server, and the terminal device hold. to make sure that the authentication key as _z, and the authentication key as _z the center server to hold matches.

(2) Communication disconnection due to a branch server failure A malfunction occurs in the branch server for some reason, and data communication is cut off. In other words, neither transmission to the network nor reception from the network is accepted as a server. Thereafter, since the terminal device does not return any response, the terminal device knows that it is independent from the server. In addition, it is assumed that a conditional minimum operation can be realized without a server in the operation of the terminal device.

(3) Returning the authentication result at the terminal device The terminal device that knows that it is independent from the branch server server in (2) still returns the next sequence 2-10 according to the rule.

[Auth_mlti_res] || E (ds _xyz , n _i || Ack _i )
Where n _i = count || MAC (ac _x * af _y , count)
Ack _i = [auth_ok] || IDx || IDy || IDz || i
[Auth_mlti_res] indicates a response. * Denotes the exclusive OR of the ac _x and af _y. Here, is used exclusive of the ac _x and af _y as the authentication key to generate the MAC value is merely an example. The authentication key used here is one authentication key stored in advance in any storage device of the terminal device that is the sender, the server that is the receiver, and other terminal devices that belong to the same group as the sender terminal device, Alternatively, it is determined in advance from an exclusive OR of a plurality of authentication keys.

  With reference to FIG. 6, the operation of the authentication unit of the terminal device when generating the response [auth_mlti_res] will be described in more detail using the terminal device 1-2-1 as an example.

  In sequences 2-7, 2-8, and 2-9 in FIG. 5, in the terminal device 1-2-1 that has received the execution command transmitted by multicast from the center server, these execution commands are input authentication information 1-5. −1 is input to the authentication unit 1-2-1-1.

For convenience, authentication information count || MAC (as _z , count) of the decryption result 1-5-4 is passed through the decryption computing unit 1-5-2. Further, this authentication information is determined by the determination unit 1-5-7 whether or not the authentication calculation is correctly performed by the authentication key as _z 1-5-6 and the MAC calculator 1-5-5, and is returned to the center. As information to be obtained, it is led to an authentication result 1-5-12. Here, since the authentication information input 1-5-1 is not encrypted, the decryption operation of the authentication information input 1-5-1 by the decryption computing unit 1-5-2 is not performed and is passed.

  Next, in order to return this authentication result to the branch office server, the MAC calculator 1-5-10 performs MAC calculation of the counter 1-5-9 and the authentication key 1-5-11, and the branch server itself (terminal device) Authentication information 1-5-13 for authenticating the user, and the above-described authentication result 1-5-12 and authentication information 1-5-13 are encrypted using the data key 1-5-14. After the encryption is performed by the device 1-5-15, it is sent to the branch office server as an authentication result reply output 1-5-16 of the following equation, as shown in sequence 2-10 in FIG.

[Auth_mlti_res] || E (ds _xyz , count || MAC (ac _x * af _y , count) || Ack _i )
here,
Ack _i = [auth_ok] || ID _x || ID _y || ID _z || i
Or Ack _i = [auth_ng] || ID _x || ID _y || ID _z || i
It is.

(4) Function at the time of abnormality detection by the monitoring unit When the terminal device 1-2-1 transmits the authentication result reply output 1-5-16, another terminal device (N002) belonging to the same group as the terminal device 1-2-1. ) 1-2-2, the terminal device (N003) 1-2-3, and the terminal device (N004) 1-2-4 receive the authentication result reply output 1-5-16, and each monitoring unit 1-2 Whether the transmission source terminal device is a legitimate terminal device is determined by -2-2, 1-2-3-2, and 1-2-4-2.

  Here, the monitoring unit 1-2-2-2 of the terminal device 1-2-2 is taken as an example and will be described with reference to FIG. The monitoring unit 1-2-2-2 is almost the same as the authentication unit illustrated in FIG. 6 except for a function that can output the monitoring result 1-6-12 from the monitoring result output 1-6-16. Although FIG. 6 and FIG. 7 are separated for convenience of explanation, functions that can be shared may be shared.

  The terminal device 1-2-2 having the same attribute value (001, 001, 001) as the transmission source terminal device 1-2-1 holds the same data key in the storage device 1-2-2-4. Therefore, the authentication result reply output 1-5-16 transmitted by the terminal device 1-2-1 can also be decrypted by the terminal device 1-2-2.

[Auth_mlti_res] || E (ds _xyz , count || MAC (ac _x * af _y , count) || Ack _i )
When the authentication result reply output 1-5-16 is input as the authentication information input 1-6-1 of the other terminal device to the monitoring unit 1-2-2-2, the decoding arithmetic unit 1-6-2 Decryption is performed using the data key ds _xyz , and count || MAC (ac _x * af _y , count) is obtained as a decryption result 1-6-4. The MAC operation unit 1-6-5 performs the MAC operation using the count of the decryption result 1-6-4 and the authentication key ac _x * af _y held in advance, and the determination unit 1-6-7 It is determined whether or not both match. Hereinafter, if the determination as to whether other terminal devices belonging to the same group are illegal is referred to as the same group unauthorized terminal device determination, the same group unauthorized terminal device determination is obtained by decoding. This is based on a comparison result between the MAC value generated based on the count value and the authentication key held in advance and the MAC value obtained by decryption.

If the two match, the decision unit 1-6-7 outputs nothing. If they do not match, the determiner 1-6-7 outputs a monitoring result 1-6-12 as a determiner output 1-6-8. Then, the authentication information 1-6-13 for the other terminal device or the like to authenticate the terminal device 1-2-2 is generated, and the monitoring result 1-6-12 and the authentication information 1-6-13 are stored in the data key ds. Encryption is performed by the cryptographic calculator 1-6-15 using _xyz, and output as a monitoring result output 1-6-16. The monitoring result 1-6-16 notifies the terminal device having the same attribute value (001, 001, 001) of the detection of the unauthorized terminal device, and also stops the function restriction command, for example, some or all of the functions. This is a command that prompts, and is an execution expression such as the following:

[Information] || E (ds _xyz , count || MAC (ac _x * af _y , count) || STOP)
Here, STOP is a function restriction command for requesting restriction of part or all of the functions of the received terminal device. Note that the determiner 1-6-7 may instruct the device control unit of the terminal device to restrict some or all of the functions together with the output of the monitoring result 1-6-8.

  According to the first embodiment, since terminal devices having the same attribute value can decrypt encrypted communication by other terminal devices, the encrypted communication transmitted by the terminal device that should have the same attribute value cannot be decrypted. In addition, it can be determined that the transmission source terminal device is an unauthorized device.

  Further, according to the present embodiment, depending on the detection of the unauthorized terminal device, not only the function of the terminal device that detected the connection of the unauthorized terminal device, but also part or all of the functions of the terminal devices belonging to the same group are restricted. be able to. As a result, it is possible to prevent damage to terminal devices of the same group due to connection of unauthorized terminal devices.

  Next, in the network system 100, as a second embodiment, an operation when an unauthorized terminal device is detected based on false status information transmitted by an unauthorized terminal device after a malfunction occurs in the operation of the host server of the terminal device. explain. This embodiment is roughly composed of the following three steps.

(1) Transmission of terminal device status before occurrence of branch server failure (2) Communication interruption due to occurrence of branch server failure (3) Transmission of unauthorized terminal device status after occurrence of branch server failure Each will be described below with reference to FIG. .

(1) Transmission of terminal device status before occurrence of branch server failure As shown in sequence 3-1, status information indicating the state of the terminal device is transmitted from a certain terminal device to the branch server as the next execution expression. .

[Status] || E (ds _xyz , count || MAC (ac _x , count) || status)
[Status] indicates that the execution expression is status information of the terminal device. “count” indicates a random number. The status concatenated with the count and the MAC value indicates the status of the terminal device as the name suggests.

The branch office server that has received the status information decrypts the encryption using the data key ds _xyz , and further confirms that the status information has arrived from the terminal device using the authentication key ac _x .

  Thereafter, the branch office server returns the following execution formula in order to notify the transmission source terminal device that the status information from the terminal device has been received, as shown in sequence 3-1-1.

[Status_res] || E (ds _xyz , count || MAC (ac _x , count) || ack)
[Status_res] indicates that this execution expression is a response on the receiving side with respect to the status information of the terminal device. “count” indicates a random number. “Ack” indicates the meaning that the branch server correctly received as the name implies.

The terminal device that has received the response information decrypts the cipher using the data key ds _xyz , and further confirms that the response information has arrived from the reliable branch server using the authentication key ac _x . This completes the exchange of status information.

(2) Communication disconnection due to branch server failure A problem has occurred in the branch server due to some reason and data communication has been interrupted. In other words, as a server, neither transmission to the network nor reception from the network can be accepted. In addition, since the terminal device does not return any response after this, the terminal device knows that it is independent from the server, and realizes the minimum conditional operation even if there is no server in the operation of the terminal device. Suppose you can.

(3) Transmission of unauthorized terminal device status after occurrence of branch server failure As shown in Sequence 3-2, it is assumed that status information such as the following execution formula, which is different from the normal packet format, is transmitted from the unauthorized terminal device. To do.

[Status] || status
As described with reference to FIG. 3, since this data can be received by other terminal devices belonging to the same group, illegal data is obtained through the processes up to the decision units 1-6-7 shown in FIG. It can be determined whether or not.

  In addition, an unauthorized terminal device may output a copy of status information recently transmitted by a legitimate terminal device by some means. In such a case, as can be seen from the correct sequence 3-1, the count used in the authentication data is updated sequentially, so that it can be determined to be illegal.

  When an unauthorized terminal device is connected, as shown in sequences 3-3, 3-4, and 3-5, the terminal device having the same attribute value detects the unauthorized terminal device, and sends the next execution expression. Temporarily stop the operation of legitimate terminal devices with the same attribute value.

[Information] || E (ds _xyz , n _i || STOP)
Where n _i = count || MAC (ac _x * af _y , count)
As a result, it is possible to take measures to temporarily stop the function of the authorized terminal device against the appearance of an unauthorized terminal device that occurs in the minimum necessary operation.

  In Example 1, the same group unauthorized terminal device determination was performed based on the MAC value comparison result. In this embodiment, CRC (Cyclic Redundancy Check) is used in combination with the MAC value comparison.

  In Example 1 (3) “Reply of authentication result at terminal device”, the terminal device sends out the following authentication result reply output 1-5-16.

[Auth_mlti_res] || E (ds _xyz , count || MAC (ac _x * af _y , count) || Ack _i )
In this case, prior to encryption with the data key _{ds xyz,} a target portion of the encrypted _{count || MAC (ac x * af} y, count) || Ack i
The CRC is generated. For this reason, as shown in FIG. 9, a CRC calculator 1-5-20 is added immediately before the cryptographic calculator 1-5-15, and the generated CRC is further concatenated to obtain a cryptographic calculator 1-5-15. And the following authentication result reply output 1-5-16a is generated.

[Auth_mlti_res] || E (ds _xyz , count || MAC (ac _x * af _y , count) || Ack _i || CRC)
In Example 1 (4) “Function at the time of abnormality detection by the monitoring function”, in Example 1, the same group unauthorized terminal device determination is performed based only on the comparison result of the MAC value. Prior to the comparison, the CRC is checked. For this reason, as shown in FIG. 10, a CRC calculator 1-6-20 and a determiner 1-6-21 are provided in the subsequent stage of the decoding calculator 1-6-2.

The decryption computing unit 1-6-2 decrypts the authentication information input 1-6-1 of the other terminal device using the data key ds _xyz held in advance. The CRC computing unit 1-6-20 is based on the output of the decoding computing unit 1-6-2.
count || MAC (ac _x * af _y , count) || Ack _i
The CRC is generated.

  The determiner 1-6-20 compares the CRC included in the output of the decoding calculator 1-6-2 with the CRC output from the CRC calculator 1-6-20. If they match, the data key used for encryption and the data key used for decryption are considered to match and do nothing. On the other hand, in the case of mismatch, the monitoring result 1-6-12 is output as the determiner output 1-6-22. The subsequent processing is the same as that in the case where the monitoring result 1-6-12 is output as the judging device output 1-6-8 in the first embodiment.

  Further, as in the first embodiment, the MAC calculator 1-6-5, the authentication key 1-6-6, and the count value obtained by decryption by the determiner 1-6-7 and the authentication key held in advance. The MAC value generated based on the above is compared with the MAC value obtained by decoding. In the case of discrepancy, the monitoring result 1-6-12 is output as the determiner output 1-6-8 in the same manner as in the first embodiment, and thereafter the same as in the first embodiment.

Based on the determination result based on the CRC calculation, it can be determined whether or not the decoding has been correctly performed. In other words, whether the other party who transmitted the authentication information input 1-6-1 of the other terminal device knows the correct encryption key ds _xyz and used it for encryption, that is, whether the other terminal device is legitimate. It can be temporarily determined whether or not. The subsequent authentication by the MAC computing unit 1-6-5 and the judging unit 1-6-7 supplements the provisional judgment by the CRC computation, and it can be considered as a function for judging whether the transmission partner is more trustworthy. Good.

  As described above, the present invention has been described with reference to the embodiments and examples. However, the present invention is not limited to these, and it can be freely modified within the technical scope of the present invention. Not too long.

  For example, in the embodiment and the example, it is the other terminal device that becomes the subject of the unauthorized terminal device detection operation, but the present invention is not limited to this, and it may be detected by the server. Moreover, although the detection target is an unauthorized terminal device, the present invention is not limited to this, and may be applied to detect an unauthorized server.

  In the above-described embodiments and examples, the terminal devices are connected to the branch office server via the hub. However, the present invention is not limited to this, and may be connected by a token ring. .

  When performing the group unauthorized terminal device determination, the first embodiment is performed based on the comparison result of the MAC value, and the third embodiment is performed based on the determination result of the success or failure of the decoding by the CRC check and the comparison result of the MAC value. However, the present invention is not limited to these, and it may be the same group unauthorized terminal device determination based only on the decoding success / failure determination result by the CRC check, or the MAC value comparison and the decoding success / failure by the CRC check Instead of the determination, or in combination with these, the same group unauthorized terminal device determination may be performed using another determination method.

  As an example of the address information of the network system 100, a MAC address and an IP address are given. However, a destination server / terminal device may be specified based on other address information. For example, the attribute value uniquely specifies a server and a terminal device in the network system 100, so the attribute value may be used as an address. In this case, the attribute value is transmitted in the plain text attached to the authentication information, and the attribute value needs to be handled as information that can be known by a third party.

100 Network system 1-1-1 Center server 1-1-2, 1-1-3 Head office server 1-1-4 to 1-1-7 Branch office server 1-1-8 to 1-1-15 Group 1 4-1 Hub 1-2-1-1, 1-2-2-1, 1-2-3-1, 1-2-4-1 recognition unit 1-2-1-2, 1-2-2 -1-2, 1-2-3-2, 1-2-4-2 monitoring unit 1-2-1-3, 1-2-2-3, 1-2-3-3, 1-2-4- 3, 1-2-1-4, 1-2-2-4, 1-2-3-4, 1-2-4-4 storage unit 1-5-1 authentication information input 1-5-2, 1 -6-2 Decryption Operation Unit 1-5-4 Decryption Results 1-5-5, 1-6-5 MAC Operation Units 1-5-6, 1-6-6 Authentication Keys 1-5-7, 1-6 -7 Judger 1-5-12 Authentication result 1-5-13 Authentication information 1-5-14 Data key 1- -15, 1-6-15 Cryptographic operator 1-5-16 Authentication result reply output 1-5-17 Device controller 1-5-20, CRC operator 1-6-1 Authentication information input 1 of other terminal device -6-3, 1-6-14 Data key 1-6-12 Monitoring result 1-6-13 Authentication information 1-6-16 Monitoring result output

Claims (37)

Each of the plurality of servers is provided with a plurality of servers, each of which includes a plurality of servers belonging to different hierarchies, and each of the servers at the lowest level includes a plurality of terminal devices. In a connected network system, when a seed is given in advance as a data key of the highest server, the terminal device belongs to the first identifier of the server belonging to any one of the layers, and the terminal device A storage device that stores a data key that is a single encryption key generated by inputting a data key of a server that belongs to a hierarchy higher than that of the server to a secret function to a third party;
One terminal device of the plurality of terminal devices, wherein a first terminal device other than the terminal device is generated based on the data key or the data key stored in the storage device of the first terminal device Decrypting means using the encryption key and decrypting encrypted data transmitted via the network system using the data key or an encryption key generated based on the data key;
A terminal device comprising: determination means for determining that the first terminal device is a legitimate terminal device according to a decryption result of the encrypted data. When a third terminal device, which is one terminal device other than the plurality of terminal devices connected to the network system, transmits data D via the network system, the determination means includes a decoding result of the data D. In response, the third terminal device is determined to be an unauthorized terminal device,
When the determining means determines that the third terminal device is an unauthorized terminal device, it instructs at least some of the plurality of terminal devices including itself to execute a predetermined process. The terminal device according to claim 1, further comprising means for transmitting a signal.   The terminal device according to claim 2, wherein the predetermined process is a process of restricting a part or all of the functions of the terminal device. The storage means stores a second identifier that is an identifier for identifying servers belonging to the same hierarchy and is an identifier kept secret from a third party,
The encrypted data includes, as at least a part thereof, data obtained by encrypting data generated based on the second identifier with the data key,
4. The terminal device according to claim 1, wherein the determination unit makes a determination based on the second identifier stored in the storage device and a decoding result of the decoding unit. 5. .   The terminal device according to claim 4, wherein the second identifier is generated by inputting the first identifier into a function kept secret from a third party. The encrypted data includes encrypted data including first data and second data which is a CRC (Cyclic Redundancy Check) of the first data,
The determination unit compares the CRC generated from the first data included in the decoding result with the second data included in the decoding result. The terminal device described.   The terminal device according to claim 1, wherein the secret function for the third party is a hash function. Each of the plurality of servers is provided with a plurality of servers, each of which includes a plurality of servers belonging to different hierarchies, and each of the servers at the lowest level includes a plurality of terminal devices. In a connected network system, when a seed is given in advance as a data key of the highest server, the terminal device belongs to the first identifier of the server belonging to any one of the layers, and the terminal device A storage device that stores a data key that is a single encryption key generated by inputting a data key of a server that belongs to a hierarchy higher than that of the server to a secret function to a third party;
Transmission means for transmitting encrypted data encrypted using the data key or an encryption key generated based on the data key via the network system;
The other terminal device of the plurality of terminal devices uses the data key stored in the storage device or an encryption key generated based on the data key and responds to a decryption result obtained by decrypting the encrypted data A terminal device characterized by receiving a determination to be performed.   Further, the other terminal device determines that one terminal device of the plurality of terminal devices is an unauthorized terminal device, and executes a predetermined process in accordance with the transmitted instruction. The terminal device according to claim 8.   The terminal device according to claim 9, wherein the predetermined process is a process of restricting a part or all of functions of the terminal device. Storing in the storage device a second identifier that is an identifier for identifying servers belonging to the same hierarchy and is an identifier kept secret from a third party;
The encrypted data includes data generated based on the second identifier and encrypted with the data key,
The terminal device according to claim 8, wherein the terminal device receives determination based on the second identifier stored in the storage device of the other terminal device and the decoding result.   The terminal device according to claim 11, wherein the second identifier is generated by inputting the first identifier into a function kept secret from a third party. The encrypted data includes encrypted first data and second data which is a CRC (Cyclic Redundancy Check) of the first data,
The said other terminal device compares CRC produced | generated from the said 1st data contained in the said decoding result, and the 2nd data contained in the said decoding result, The Claims 8 thru | or 12 characterized by the above-mentioned. A terminal device according to any one of the above.   The terminal device according to claim 8, wherein the secret function for the third party is a hash function. Each of the plurality of servers is provided with a plurality of servers, each of which includes a plurality of servers belonging to different hierarchies, and each of the servers at the lowest level includes a plurality of terminal devices. In a connected network system, when a seed is given in advance as a data key of the highest server, the terminal device belongs to the first identifier of the server belonging to any one of the layers, and the terminal device A storage procedure for storing, in a storage device, a data key that is one encryption key generated by inputting a data key of a server that belongs to a level higher than that server to a secret function to a third party When,
A terminal device of the plurality of terminal devices, wherein a first terminal device other than the terminal device encrypts the data using the data key stored in the storage device of the first terminal device; A first decryption procedure for decrypting encrypted data transmitted via the system;
A first determination procedure for determining that the first terminal device is a legitimate terminal device according to a decryption result of the encrypted data;
A program that causes a computer to execute. A second decoding procedure for decoding data D transmitted through the network system by a third terminal device that is one terminal device other than the plurality of terminal devices connected to the network system;
A second determination procedure for determining that the third terminal device is an unauthorized terminal device according to a decoding result of the data D;
When it is determined in the second determination procedure that the third terminal device is an unauthorized terminal device, execution of a predetermined process for at least some of the plurality of terminal devices including itself The program according to claim 15, for causing the computer to further execute a procedure for instructing.   The program according to claim 16, wherein the predetermined process is a process that restricts a part or all of the functions of the terminal device. In the storage procedure, a second identifier that is an identifier for mutually identifying servers belonging to the same hierarchy and is kept secret from a third party is a server corresponding to the second identifier. And stored in a storage device of a terminal device belonging to the server,
The encrypted data includes data generated based on the second identifier and encrypted with the data key,
The first determination procedure is determined based on the second identifier stored in a storage device in the storage procedure and a decoding result in the first decoding procedure. The program in any one of thru | or 17.   The program according to claim 18, wherein the second identifier is generated by inputting the first identifier into a function kept secret from a third party. The encrypted data includes encrypted data including first data and second data which is a CRC (Cyclic Redundancy Check) of the first data,
20. The CRC generated from the first data included in the decoding result and the second data included in the decoding result are compared in the first determination procedure. A program according to any of the above.   21. The program according to claim 15, wherein the secret function for the third party is a hash function. Each of the plurality of servers is provided with a plurality of servers, each of which includes a plurality of servers belonging to different hierarchies, and each of the servers at the lowest level includes a plurality of terminal devices. In a connected network system, when a seed is given in advance as a data key of the highest server, the terminal device belongs to the first identifier of the server belonging to any one of the layers, and the terminal device A storage procedure for storing a data key, which is a single encryption key generated by inputting a data key of a server belonging to a hierarchy above that server to a third party as a secret function;
Causing a computer to execute a transmission procedure for transmitting encrypted data encrypted using the data key or an encryption key generated based on the data key, via the network system;
The other terminal device of the plurality of terminal devices uses the data key stored in the storage device or an encryption key generated based on the data key and responds to a decryption result obtained by decrypting the encrypted data A program that causes the computer to receive the determination to be performed.   Further, when the other terminal device receives an instruction transmitted by determining that one terminal device of the plurality of terminal devices is an unauthorized terminal device, a predetermined process is performed according to the instruction. The program according to claim 22, wherein the program is executed.   The program according to claim 23, wherein the predetermined process is a process of restricting a part or all of the functions of the terminal device. Storing in the storage device a second identifier that is an identifier for identifying servers belonging to the same hierarchy and is an identifier kept secret from a third party;
The encrypted data includes data generated based on the second identifier and encrypted with the data key,
The program according to any one of claims 22 to 24, which receives a determination based on the second identifier stored in the storage device of the other terminal device and the decoding result.   26. The program according to claim 25, wherein the second identifier is generated by inputting the first identifier into a function kept secret from a third party. The encrypted data includes encrypted first data and second data which is a CRC (Cyclic Redundancy Check) of the first data,
27. The other terminal device compares the CRC generated from the first data included in the decoding result with the second data included in the decoding result. The program according to any one.   28. The program according to claim 22, wherein the secret function for the third party is a hash function.   A computer-readable recording medium storing the program according to any one of claims 15 and 28. Each with multiple servers belonging to different tiers,
A first identifier for identifying servers belonging to the same hierarchy from each other is given to each of the plurality of servers,
Multiple terminal devices are connected to each lowermost server,
At least one of the terminal device according to claim 1 and the computer that operates according to the program according to claims 15 to 21,
A network system comprising at least one of the terminal device according to claim 8 and a computer that operates according to the program according to claim 22. Each of the plurality of servers is provided with a plurality of servers, each of which includes a plurality of servers belonging to different hierarchies, and each of the servers at the lowest level includes a plurality of terminal devices. In a connected network system, when a seed is given in advance as a data key of the highest server, the terminal device belongs to the first identifier of the server belonging to any one of the layers, and the terminal device A data key that is a single encryption key generated by inputting a data key of a server that is one level higher than that server into a secret function with respect to a third party is obtained from the plurality of terminal devices. A storage stage to store in each storage device;
A first terminal device that is one terminal device among the plurality of terminal devices uses the network system to encrypt data that is encrypted using the data key or an encryption key generated based on the data key. A transmission stage to transmit via,
A receiving step in which a second terminal device that is one terminal device of the plurality of terminal devices and is a terminal device other than the first terminal device receives the encrypted data;
A decryption step in which the second terminal device decrypts the encrypted data using the data key stored in its storage device or an encryption key generated based on the data key;
A terminal device management method, comprising: a determination step in which the second terminal device determines that the first terminal device is a legitimate terminal device according to a decryption result of the encrypted data. In the transmission stage, a third terminal device that is one terminal device other than the plurality of terminal devices connected to the network system transmits data D,
In the reception stage, the second terminal device receives the data D,
In the decoding step, the second terminal device decodes the data D,
In the determination step, the second terminal device determines that the third terminal device is an unauthorized terminal device according to the decoding result of the data D,
Furthermore, when it is determined in the determination step that the third terminal device is an unauthorized terminal device, the second terminal device is configured to at least a part of the plurality of terminal devices including itself. 32. The terminal device management method according to claim 31, further comprising a step of instructing execution of a predetermined process.   The terminal device management method according to claim 32, wherein the predetermined process is a process of restricting a part or all of the functions of the terminal device. In the storage step, a second identifier that is an identifier for mutually identifying servers belonging to the same hierarchy and is kept secret from a third party is a server corresponding to the second identifier. And stored in a storage device of a terminal device belonging to the server,
In the transmission stage, the first terminal device encrypts and transmits data generated based on the second identifier as the at least part of the encrypted data with the data key,
In the determination step, the second terminal device makes a determination based on the second identifier stored in the storage device in the storage step and the decoding result in the decoding step. The terminal device management method according to claim 31.   The terminal device management method according to claim 34, wherein the second identifier is generated by inputting the first identifier into a function kept secret from a third party. In the transmission step, data including first data and second data that is a CRC (Cyclic Redundancy Check) of the first data is encrypted.
In the determination step, the second terminal device compares the CRC generated from the first data included in the decoding result with the second data included in the decoding result. The terminal device management method according to any one of claims 31 to 35.   37. The terminal device management method according to claim 31, wherein the secret function for the third party is a hash function.

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