WO2012090332A1

WO2012090332A1 - Key setting method, node, server, and network system

Info

Publication number: WO2012090332A1
Application number: PCT/JP2010/073814
Authority: WO
Inventors: 伊豆　哲也; 武仲　正彦; 和快古川; 尚兒島
Original assignee: 富士通株式会社
Priority date: 2010-12-28
Filing date: 2010-12-28
Publication date: 2012-07-05
Also published as: JPWO2012090332A1; JP5494829B2

Abstract

Provided are a key setting method, a node, a server, and a network system, whereby: an ad hoc network (Ab) is installed after an ad hoc network (Aa) is installed; nodes (Nc, Nb) are within a communications area; once the node (Nb) is installed, the node (Nb) may sometimes be closer than a node (Na) to the node (Nc); and data from the node (Nc) is more efficiently uploaded to a management server (101) via the node (Nb) and a gateway (Gb). Accordingly, an ad hoc network (Ab) gateway (Gb) specific encryption key (Kb) is assigned after the fact to the node (Nc) that holds only an encryption key (Ka). As a result, the node (Nc) can autonomously select a gateway (Ga, Gb) and upload data for the node (Nc) to the management server (101).

Description

Key setting method, node, server, and network system

The present invention relates to a key setting method for setting a key for encrypting data, a node, a server, and a network system.

An ad hoc network is a type of self-configuring network that is linked by wireless communication. An ad hoc network is composed of a plurality of nodes. Each node in the ad hoc network transmits and receives packets by multi-hop communication. Multi-hop communication is a technique in which nodes that do not exist within each other's communication area communicate with each other via another node that exists within the communication area of each node.

In addition, when connecting an ad hoc network and another network such as the Internet, LAN (Local Area Network), WAN (Wide Area Network), etc., communication between networks is transferred using a relay device called a gateway.

Also, if the number of nodes belonging to the ad hoc network becomes larger than a certain level, processing with one gateway becomes difficult. In such a case, the processing is distributed by providing a plurality of gateways.

As described above, in multi-hop communication in an ad hoc network, communication between nodes is performed autonomously through a route selected by a relaying node, and therefore the route changes every moment depending on the state of each node and the communication environment. The same applies to an ad hoc network having a plurality of gateways. When a node communicates with another network, which gateway is relayed generally varies depending on the state of the network. The ad hoc network has a feature that it has autonomy and robustness by such free route selection.

On the other hand, as a technology using an ad hoc network, there is a system in which a node capable of wireless communication is incorporated into a power meter in each home, and a worker performs work such as meter confirmation via an ad hoc network without going to the site. In an ad hoc network that handles personal information such as the amount of power used in each home, it is required to perform secure communication from the viewpoint of confidentiality and tampering prevention.

Therefore, conventionally, secure communication is ensured by encrypting packets transmitted and received between nodes in the ad hoc network. At this time, it is generally performed that secure communication is performed by using one encryption key used in the system and each node or gateway holding this key.

However, if a common encryption key is used by all nodes in the system, there is a risk that the contents of communication in the entire system will be leaked if one key is analyzed and the key is leaked. Therefore, it is required to reduce the risk at the time of key leakage by using a plurality of keys used in the system.

Also, when the new node is initially introduced into the system, the new node cannot communicate securely with other nodes in the ad hoc network until the encryption key is set. For this reason, it is difficult to automatically set an encryption key to a new node via an ad hoc network, and an operator may go to the site to set the encryption key.

Also, as a prior art related to secure communication, for example, there is a technique for managing an encryption key of a network that performs communication by broadcast (see, for example, Patent Document 1 below). There is also a technique for stably performing key exchange at the start of communication in an ad hoc network (see, for example, Patent Document 2 below). There is also a technique for each node in an ad hoc network to select an adaptive gateway (see, for example, Patent Document 3 below).

Further, as a prior art related to secure communication, for example, there is a technique for acquiring various types of communication control information necessary for a terminal to perform communication control from an authentication server using another communication device different from the terminal (for example, (See Patent Document 4 below.) In addition, there is a technique related to an ad hoc network in which each communication terminal performs mutual authentication with the nearest communication terminal using a public key (see, for example, Patent Document 5 below).

JP 2003-348072 A JP 2007-88799 A JP 2009-81854 A JP 2006-135874 A JP 2007-13386 A

However, the above-described prior art has a problem that when the encryption key set for each node in the ad hoc network is changed for each gateway, it is difficult to specify the gateway to which the new node belongs at the initial introduction of the new node. It was. For example, even if the candidate gateways can be narrowed down from the address of the installation location of the new node, the communication status changes depending on factors such as the weather and the positional relationship with a nearby building. For this reason, it is necessary for the worker to go to the site to check which gateway is actually communicable, and there is a problem in that the work time and work load required for the work of setting the encryption key of the worker are increased. .

In addition, when a node of another ad hoc network is installed in the communication range afterwards, the encryption key is different from the other ad hoc network node because the gateway used is different. Therefore, it is necessary for the worker to go to the site for confirmation, and there is a problem that the work time and work load required for the work of setting the encryption key of the worker are increased.

In addition, when an encryption key of another ad hoc network cannot be additionally set, communication cannot be performed via another ad hoc network even though communication with a node of the other ad hoc network is possible. Therefore, there is a problem that the autonomous gateway that is one of the features of the ad hoc network cannot be selected, and the robustness is reduced, which may lead to a reduction in communication efficiency.

In addition, when another ad hoc network is removed, the encryption key is unnecessary, but if the node located at the boundary with the other ad hoc network keeps the unnecessary encryption key, it is unnecessary in the first place. There is a problem that a heavy decryption process is performed and a load due to data processing increases.

An object of one aspect of the present invention is to improve the efficiency of setting work of encryption keys used by nodes in an ad hoc network. In another aspect, the purpose is to increase the efficiency of communication by maintaining the autonomy and robustness of ad hoc networks by dynamically adding encryption keys in response to the establishment or removal of other ad hoc networks. And

As one aspect of the present invention, a node in any one of the ad hoc networks that performs encryption and decryption with a gateway-specific first key in any one of a plurality of ad hoc networks is received by the encrypted packet A gateway that is a destination or a transmission source is detected for each encrypted packet, and the number of failures in which the encrypted packet could not be decrypted with the first key is counted for each detected gateway. It is determined for each gateway whether the number is greater than or equal to a threshold value related to key acquisition, and a second key acquisition request specific to the gateway determined to be equal to or greater than the threshold value Send it to the server that stores the key unique to each gateway via one of the above ad hoc networks. As a result of the acquisition request being transmitted, the second key stored in the server is received from the server via any one of the ad hoc networks, and the received second key is encrypted and A key setting method, a node, and a network system for setting a key for decryption are proposed.

Also, as one aspect of the present invention, a node in any one of the ad hoc networks that performs encryption and decryption with a first key unique to a gateway in any one of a plurality of ad hoc networks is received encryption. A destination address or source gateway of the encrypted packet is detected for each encrypted packet, and the number of successful decryptions of the encrypted packet with the first key is counted for each detected gateway. The number of failures that could not decrypt the encrypted packet with the first key is counted for each gateway, and the difference obtained by subtracting the number of successes from the number of failures counted is greater than or equal to a threshold for key acquisition. For each gateway, and it is necessary to acquire a second key specific to the gateway that is determined to be equal to or greater than the threshold. Is transmitted to the server storing the key specific to each gateway of the plurality of ad hoc networks via any one of the ad hoc networks, and the second request stored in the server as a result of the acquisition request being transmitted. A key setting method, a node, and a network system are proposed in which a key is received from the server via any one of the ad hoc networks, and the received second key is set as a key for encryption and decryption. .

Also, as one aspect of the present invention, encryption and decryption are performed using a first key specific to a gateway in an ad hoc network of any one of a plurality of ad hoc networks and a second key specific to another gateway in another ad hoc network. The node in any one of the ad hoc networks to perform counts the number of successes that can be decrypted with the first key and counts the number of successes that can be decrypted with the second key for each received encrypted packet Then, it is determined whether each counted number of successes is less than or equal to a threshold value related to canceling the setting. A key setting method, a node, and a network system for setting a key to a key that does not perform encryption and decryption are proposed.

Also, as one aspect of the present invention, encryption and decryption are performed using a first key specific to a gateway in an ad hoc network of any one of a plurality of ad hoc networks and a second key specific to another gateway in another ad hoc network. The node in any one of the ad hoc networks to perform counts the number of successes that can be decrypted with the first key and counts the number of successes that can be decrypted with the second key for each received encrypted packet Then, a key setting method, a node, and a network system are proposed in which the key with the smaller number of successes out of the first key and the second key is set as a key that does not perform the encryption and decryption. .

Further, as one aspect of the present invention, a server capable of communicating with each gateway of a plurality of ad hoc networks stores the gateway identification information and the gateway-specific key for each gateway, and the plurality of ad hoc networks A request for obtaining a second key specific to the gateway, which is different from the first key specific to the gateway in any one of the ad hoc networks, from a node in any one of the ad hoc networks via the one of the ad hoc networks The second key is extracted based on the identification information of the gateway using the second key included in the received second key acquisition request received, and the extracted second Key setting method for transmitting the key of the server to the node via any one of the ad hoc networks, , And the network system is proposed.

According to this key setting method, node, server, and network system, it is possible to improve the efficiency of setting the encryption key used by the nodes in the ad hoc network. Further, by dynamically adding an encryption key in accordance with the establishment or removal of another ad hoc network, there is an effect that it is possible to maintain the autonomy and robustness of the ad hoc network and improve the efficiency of communication.

FIG. 1 is an explanatory diagram illustrating a first example of a network system. FIG. 2 is an explanatory diagram illustrating a second example of the network system. FIG. 3 is an explanatory diagram showing a third example of the network system. FIG. 4 is an explanatory diagram illustrating a fourth example of the network system. FIG. 5 is an explanatory diagram showing an embodiment of the network system. FIG. 6 is an explanatory diagram showing an example of introducing a new node of the downstream type into the network system according to the present embodiment. FIG. 7 is a sequence diagram (part 1) illustrating an operation example of the network system at the time of introducing a new node of the downstream type according to the embodiment. FIG. 8 is a sequence diagram (part 2) illustrating an operation example of the network system at the time of introducing a new node of the downstream type according to the embodiment. FIG. 9 is an explanatory diagram showing an example of introducing an upstream type new node into the network system according to the present embodiment. FIG. 10 is a sequence diagram illustrating an operation example of the network system when a new node is introduced. FIG. 11 is an explanatory diagram (part 1) of an example of adding an encryption key to a boundary node in the network system. FIG. 12 is an explanatory diagram (part 2) of an example of adding an encryption key to a boundary node in the network system. FIG. 13 is an explanatory diagram (part 3) illustrating an example of adding the encryption key to the boundary node in the network system. FIG. 14 is an explanatory diagram (part 4) illustrating an example of adding the encryption key to the boundary node in the network system. FIG. 15 is an explanatory diagram (part 5) of an example of adding the encryption key to the boundary node in the network system. FIG. 16 is an explanatory diagram (part 6) of an example of adding the encryption key to the boundary node in the network system. FIG. 17 is a block diagram illustrating a hardware configuration example of the management server. FIG. 18 is a block diagram illustrating a hardware configuration example such as a node. FIG. 19 is an explanatory diagram showing an example of the contents stored in the encryption key DB. FIG. 20 is a block diagram illustrating a functional configuration example of a node. FIG. 21 is an explanatory diagram (part 1) of a data structure example of an encrypted packet encrypted with an encryption key. FIG. 22 is an explanatory diagram (part 2) of a data structure example of an encrypted packet encrypted with an encryption key. FIG. 23 is an explanatory diagram of an exemplary data structure of an acquisition request packet. FIG. 24 is an explanatory diagram (part 1) illustrating an example of storage contents of a management table in a node. FIG. 25 is an explanatory diagram (part 2) of an example of stored contents of the management table in the node. FIG. 26 is an explanatory diagram (part 3) of an example of stored contents of the management table in the node. FIG. 27 is a flowchart showing a packet transfer processing procedure of a node (boundary node). FIG. 28 is a flowchart showing a detailed processing procedure of the decoding process (step S2703) shown in FIG. FIG. 29 is a flowchart showing a detailed processing procedure of the decoding process (step S2703) shown in FIG. FIG. 30 is a flowchart (part 1) illustrating the encryption key addition processing procedure of the node. FIG. 31 is a flowchart (part 2) illustrating the encryption key addition processing procedure of the node. FIG. 32 is a block diagram illustrating a functional configuration example of the management server. FIG. 33 is an explanatory diagram of an example of decryption of the encryption acquisition request packet. FIG. 34 is an explanatory diagram of a specific example of history information. FIG. 35 is an explanatory diagram of a data structure example of a response packet. FIG. 36 is a flowchart (No. 1) showing the key provision processing procedure of the management server. FIG. 37 is a flowchart of a detailed process procedure of the decryption process (step S3602) depicted in FIG. FIG. 38 is a flowchart (part 2) illustrating the key provision processing procedure of the management server. FIG. 39 is a flowchart (part 1) illustrating a detailed processing procedure of the validity determination processing (step S3800). FIG. 40 is a flowchart (part 2) illustrating the detailed processing procedure of the validity determination processing (step S3800). FIG. 41 is a flowchart (part 3) illustrating a detailed processing procedure of the validity determination processing (step S3800). FIG. 42 is an explanatory diagram (part 1) of an example of updating the node management table T. FIG. 43 is an explanatory diagram (part 2) of an example of updating the node management table T. FIG. 44 is a flowchart (No. 1) showing the node key setting release processing procedure. FIG. 45 is a flowchart (part 2) of the node key setting release processing procedure.

Hereinafter, embodiments of a key setting method, a node, a server, and a network system according to the present invention will be described in detail with reference to the accompanying drawings. An ad hoc network is an autonomous distributed wireless network configured by a group of nodes that can be connected wirelessly without requiring an access point such as a wireless LAN. In this specification, a gateway (so-called sink node) is also included in the ad hoc network.

In an ad hoc network, the encryption key set in each node in the ad hoc network may be changed for each gateway for security or the like. In this way, when changing the encryption key for each gateway, autonomous, which is possible in an ad hoc network that does not consider security (that is, the encryption key is not used) or an ad hoc network in which all nodes share one encryption key. A situation occurs where the gateway cannot be selected. Therefore, there is a possibility that the communication efficiency may be reduced by reducing the robustness that is one of the features of the ad hoc network.

In this embodiment, in order to secure the autonomy and robustness of the ad hoc network, a gateway-specific encryption key in each ad hoc network is assigned to each node located at the boundary of the plurality of ad hoc networks. At this time, when one encryption key has already been assigned and the other encryption key has not been assigned yet, the node located at the boundary acquires the other encryption key securely and automatically.

Also, if necessary, it is also determined whether or not the other encryption key is appropriate, and if it is appropriate, the other encryption key of the node located at the boundary is acquired securely and automatically. As a result, the gateway located at the boundary can autonomously select the gateway, and the communication efficiency of the ad hoc network can be improved. Hereinafter, it demonstrates using drawing.

FIG. 1 is an explanatory diagram showing a first example of a network system. In FIG. 1, the management server 101 and the gateway Ga can communicate with each other via the network NW1. In FIG. 1, to simplify the description, the number of gateways is one and the number of nodes is two. The gateway Ga and the nodes Na and Nc constituting the ad hoc network Aa hold an encryption key Ka unique to the gateway Ga.

In the network system of FIG. 1, the gateway Na broadcasts the encrypted packet SPa encrypted with the encryption key Ka, so that the node Na receives the encrypted packet SPa. Since the node Na can decrypt the received encrypted packet SPa with the encryption key Ka, multi-hop communication is realized by transferring the encrypted packet SPa to the node Nc. The node Nc also decrypts the encrypted packet SPa with the encryption key Ka. As a result, the data embedded in the encrypted packet SPa is distributed to the nodes Na and Nc.

In addition, when uploading data from the nodes Na and Nc to the gateway Ga, the encrypted packet SPa is transmitted to the gateway Ga to reach the gateway Ga by multi-hop communication.

FIG. 2 is an explanatory diagram showing a second example of the network system. The second example shown in FIG. 2 is an example in which an ad hoc network Ab is further installed after the ad hoc network Aa shown in FIG. 1 is installed. In order to simplify the description, it is assumed that the ad hoc network Ab is composed of one gateway Gb and one node Nb. The gateway Gb and the node Nb hold an encryption key Kb unique to the gateway Gb. As in the case of FIG. 1, the encrypted packet SPb encrypted with the encryption key Kb also circulates within the ad hoc network Ab.

Here, it is assumed that the node Nc and the node Nb are within communication range. A node within the communication range of a plurality of ad hoc network nodes (nodes Na and Nb in FIG. 2), such as the node Nc, is referred to as a “boundary node”.

In FIG. 1, since the node Nc is the only neighboring node (the node within the communication range) of the node Nc, the node Nc communicates with the node Na. However, as shown in FIG. 2, the node Nb in the ad hoc network Ab Is installed, the node Nb may be closer to the node Nc than the node Na. In such a case, it is more efficient to upload the data of the node Nc to the management server 101 via the node Nb and the gateway Gb, but the node Nc does not hold the encryption key Kb. For this reason, the node Nc has to upload data to the management server 101 via the node Na and the gateway Ga for security, although the node Nb is located closer.

FIG. 3 is an explanatory diagram showing a third example of the network system. The third example shown in FIG. 3 shows an example in which the encryption key Kb is assigned to the node Nc in the second example of FIG. In the present embodiment, as in the third example, by adding the encryption key Kb unique to the gateway Gb of the ad hoc network Ab to the node Nc that holds only the encryption key Ka, the node Nc The gateways Ga and Gb can be selected autonomously and the data of the node Nc can be uploaded to the management server 101.

FIG. 4 is an explanatory diagram showing a fourth example of the network system. The fourth example shown in FIG. 4 shows an example in which the ad hoc network Aa is removed in the third example of FIG. Even when the ad hoc network Aa is removed, if the encryption key Ka is left in the node Nc, the node Nc tries to encrypt or decrypt with the encryption key Ka. Even if the encrypted packet SPa encrypted with the encryption key Ka is transmitted, it is eventually discarded at the node Nb. Therefore, the encryption process with the encryption key Ka and the transmission of the encrypted packet SPa are useless.

Therefore, in this embodiment, when the ad hoc network Aa is removed as in the fourth example, the encryption key Ka of the removed ad hoc network Aa is deleted at the node Nc. Thereby, useless encryption processing and communication processing can be eliminated, and the efficiency of communication within the remaining ad hoc network Ab can be improved.

(One embodiment of network system)
FIG. 5 is an explanatory diagram showing an embodiment of the network system. In FIG. 5, the network system 100 includes a management server 101, gateways G1 to Gn, nodes N1-1 to N1-m1,..., Ni-1 to Ni-mi, ..., Nn-1 to Nn-mn, It is the structure containing.

In the network system 100, the management server 101 and the gateways G1 to Gn are connected to each other via a network NW1 such as the Internet, LAN, or WAN. The gateway Gi and the nodes Ni-1 to Ni-mi are connected via the ad hoc network Ai (i = 1, 2,..., N).

Here, the management server 101 is a computer that includes an encryption key DB (database) 110 and manages encryption keys unique to the gateways G1 to Gn. The encryption key unique to the gateway Gi (hereinafter referred to as “encryption key Ki”) is key information for encrypting packets transmitted and received between nodes in the ad hoc network Ai to which the gateway Gi belongs. A detailed description of the encryption key DB 110 will be described later with reference to FIG.

The gateway Gi is a relay device that connects the ad hoc network Ai and the network NW1. The gateway Gi understands both the protocol of the ad hoc network Ai and the protocol of the network NW1, and transfers communication between the ad hoc network Ai and the network NW1.

Nodes Ni-1 to Ni-mi are wireless communication devices that perform multi-hop communication with other nodes within a predetermined communication range. In the ad hoc network Ai, it is not necessary for all the nodes Ni-1 to Ni-mi to directly communicate with the gateway Gi, and it is sufficient that some nodes can communicate with the gateway Gi.

The network system 100 can be applied to, for example, a system that collects the amount of power and gas used in each household. Specifically, for example, by incorporating each node Ni-1 to Ni-mi into a power meter or gas meter in each home, the amount of power or gas used in each home is transmitted and received between nodes in the ad hoc network Ai. Note that the power consumption and gas consumption of each household may be measured by each node Ni-1 to Ni-mi, or each node Ni-1 to Ni-mi may be obtained from a power meter or gas meter. Good.

The gateway Gi uses the power and gas usage of each home received from the nodes Ni-1 to Ni-mi in the ad hoc network Ai to the server of the power company or gas company (for example, the management server 101) via the network NW1. Send to. As a result, the amount of power and gas used can be collected without the need for workers to visit the site.

In the network system 100, the packet is encrypted using the encryption key unique to the gateway Gi for each ad hoc network Ai. This ensures secure communication (data confidentiality, tampering prevention, etc.) of the ad hoc network Ai. Moreover, the risk at the time of key leakage is reduced by changing an encryption key for every ad hoc network Ai.

In the example of FIG. 5, a single gateway Gi is provided in the ad hoc network Ai. However, a plurality of gateways Gi may be provided in the same ad hoc network Ai. In this case, an encryption key for encrypting a packet transmitted / received in the ad hoc network Ai is common to a plurality of gateways Gi.

Note that, in each of the nodes Ni-1 to Ni-mi in the ad hoc network Ai, the encrypted packet encrypted with the encryption key unique to the gateway Gi is transferred according to the routing table broadcast from the gateway Gi in advance. Since the transfer source address and the transfer destination address are defined in the routing table, the encrypted packet from the transfer source node is transferred to the transfer destination node.

Also, when there is no routing table, it is transmitted to neighboring nodes in the communication area. In each of the nodes Ni-1 to Ni-mi of the ad hoc network Ai, packets that could not be decrypted with the encryption key unique to the gateway Gi held are discarded. Therefore, an upper limit of the number of transfer times should be specified in the packet. Thus, multi-hop communication can be performed at the destination. In addition, an encrypted packet that could not be decrypted is discarded, but receiving an encrypted packet that cannot be decrypted in this way is referred to as “interception”.

(Setting example of encryption key when introducing a new node)
Next, an example of setting an encryption key when a new node is introduced into the network system 100 shown in FIG. 5 will be described with reference to FIGS. There are two types of key setting processes, a downstream type and an upstream type. The downstream type is a process for setting a key by broadcasting a packet from an upstream side (gateway) to a new node. The upstream type is a process for setting a key by uploading a packet from a new node to the upstream side (gateway).

The downstream type will be described with reference to FIGS. The upstream type will be described with reference to FIGS. 9 and 10. In this embodiment, a plurality of encryption keys are set for the boundary node. Here, an example in which one encryption key is set will be described first, and then an additional setting example of keys will be described. explain.

FIG. 6 is an explanatory diagram showing an example of introducing a new node by the downstream type into the network system 100 according to the present embodiment. In FIG. 6, a new node Ni-x is introduced into the ad hoc network Ai of the network system 100. In FIG. 6, among the nodes Ni-1 to Ni-mi in the ad hoc network Ai, nodes Ni-1 to Ni-3 are shown as representatives.

When the new node Ni-x is introduced, the worker OP does not know which ad hoc network Ai the new node Ni-x belongs to. Therefore, the new node Ni-x intercepts from the neighborhood and transmits the encrypted packet from the gateway Gi to the management server 101 by using the mobile terminal MT used by the worker OP, whereby the new node Ni-x The management server 101 is inquired about the encryption key Ki to be set to. As a result, an appropriate encryption key Ki is acquired from the management server 101 and automatically set to the new node Ni-x.

Here, the mobile terminal MT is a mobile communication device used by the worker OP, and is, for example, a mobile phone, a PHS (Personal Handy-phone System) phone, a smartphone, a notebook personal computer, or the like. The mobile terminal MT relays communication between the new node Ni-x that cannot communicate directly and the management server 101.

7 and 8 are sequence diagrams showing an operation example of the network system 100 when the downstream type new node Ni-x according to the embodiment is introduced. The sequence in FIG. 7 is an operation example performed until the worker OP goes to the site (place where the new node Ni-x is installed), for example. The sequence in FIG. 8 is an example of an operation performed after the worker OP goes to the site, for example.

7, (1) the gateway Gi transmits the encryption key Ki unique to the gateway Gi to the management server 101. (2) The management server 101 associates and registers the encryption key Ki unique to the gateway Gi and the address of the gateway Gi in the encryption key DB 110.

(3) The gateway Gi broadcasts (simultaneously reports) a packet (hereinafter referred to as “encrypted packet SPi”) encrypted using the encryption key Ki unique to the gateway Gi to the ad hoc network Ai. For example, the address of the gateway Gi is included in the encrypted packet SPi.

(4) The node Ni-1 transmits the encrypted packet SPi from the gateway Gi to the node Ni-3 in the communication area. (5) The node Ni-3 intercepts the encrypted packet SPi transmitted by the node Ni-1. (6) The new node Ni-x records the encrypted packet SPi from the node Ni-3. However, at this time, the new node Ni-x cannot decrypt the encrypted packet SPi because the encryption key Ki is not set.

8, (7) the mobile terminal MT is connected to the management server 101 via a network NW2 such as a mobile phone network or the Internet. At this time, the mobile terminal MT performs existing secure communication with the management server 101 using, for example, SSL (Secure Socket Layer).

(8) The mobile terminal MT is connected to the new node Ni-x via the wired or wireless network NW3. Specifically, for example, when the worker OP connects the mobile terminal MT and the new node Ni-x using a USB (Universal Serial Bus) cable, the mobile terminal MT and the new node Ni-x are connected. In the meantime, the network NW3 is established.

(9) The new node Ni-x transmits the encrypted packet SPi recorded in (6) shown in FIG. 7 to the mobile terminal MT via the network NW3. (10) The mobile terminal MT transmits the encrypted packet SPi from the new node Ni-x to the management server 101 via the network NW2.

(11) The management server 101 extracts the encryption key Ki for decrypting the encrypted packet SPi from the mobile terminal MT from the encryption key DB 110. Specifically, for example, the management server 101 extracts the encryption key Ki stored in association with the address of the gateway Gi included in the encrypted packet SPi from the encryption key DB 110.

(12) The management server 101 transmits the extracted encryption key Ki to the mobile terminal MT via the network NW2. (13) The mobile terminal MT transmits the encryption key Ki from the management server 101 to the new node Ni-x via the network NW3. (14) The new node Ni-x sets the encryption key Ki from the mobile terminal MT as a key for encrypting the packet.

In this way, the new node Ni-x makes a key request to the management server 101 via the portable terminal MT, using the encrypted packet SPi from the gateway Gi that can be received even if the encryption key Ki for secure communication is not set. By doing so, the encryption key Ki to be set can be acquired.

FIG. 9 is an explanatory diagram showing an example of introducing an upstream type new node to the network system 100 according to the present embodiment. In FIG. 9, a new node Ni-x is introduced in the ad hoc network Ai of the network system 100. In FIG. 9, among the nodes Ni-1 to Ni-mi in the ad hoc network Ai, nodes Ni-1 to Ni-3 are shown as representatives.

When the new node Ni-x is introduced, the worker OP does not know which ad hoc network Ai the new node Ni-x belongs to. Therefore, in the present embodiment, using the mobile terminal MT used by the worker OP, an acquisition request for the encryption key Ki to be set in the new node Ni-x is uploaded to the ad hoc network Ai. At this time, the gateway Gi uploads the encryption key Ki unique to the gateway Gi to the management server 101. Then, the new node Ni-x acquires the encryption key Ki uploaded to the management server 101 from the management server 101 via the mobile terminal MT, and automatically sets it to the new node Ni-x. Hereinafter, an operation example of the network system 100 when the new node Ni-x is introduced will be described.

FIG. 10 is a sequence diagram showing an operation example of the network system 100 when a new node is introduced. In the sequence of FIG. 10, (1) the mobile terminal MT is connected to the management server 101 via the network NW2. At this time, the mobile terminal MT performs existing secure communication with the management server 101 using, for example, SSL.

(2) The mobile terminal MT is connected to the new node Ni-x via the wired or wireless network NW3. Specifically, for example, the worker OP connects the mobile terminal MT and the new node Ni-x using a USB cable, so that the network NW3 is connected between the mobile terminal MT and the new node Ni-x. Established.

(3) When the new node Ni-x detects the connection with the mobile terminal MT, the new node Ni-x broadcasts to the ad hoc network Ai a key acquisition request for encrypting a packet transmitted / received by multihop communication in the ad hoc network Ai. . Here, the key acquisition request is transmitted to the node Ni-3 existing in the communication area of the new node Ni-x.

(4) The node Ni-3 transmits a key acquisition request from the new node Ni-x to the node Ni-1 in the communication area. (5) The node Ni-1 transmits a key acquisition request from the node Ni-3 to the gateway Gi in the communication area. As a result, the key acquisition request from the new node N is transferred to the gateway Gi in the ad hoc network Ai.

(6) Upon receiving the key acquisition request from the new node Ni-x, the gateway Gi transmits the encryption key Ki unique to the gateway Gi to the management server 101. (7) The management server 101 transmits the encryption key Ki unique to the gateway Gi from the gateway Gi to the mobile terminal MT via the network NW2.

(8) The mobile terminal MT transmits the encryption key Ki unique to the gateway Gi from the management server 101 to the new node Ni-x via the network NW3. (9) The new node Ni-x sets the encryption key Ki from the mobile terminal MT as a key for encrypting the packet.

The connection between the mobile terminal MT and the new node Ni-x is maintained until the setting of the encryption key Ki for the new node Ni-x is completed. Further, when the setting of the encryption key Ki is completed and the connection between the mobile terminal MT and the new node Ni-x is disconnected, the encryption key Ki may be automatically deleted from the mobile terminal MT. Thereby, the risk when the mobile terminal MT is lost can be reduced.

Thus, when the new node Ni-x is introduced, a temporary communication path between the new node Ni-x and the management server 101 can be established via the portable terminal MT of the worker OP. Further, as a result of the key acquisition request broadcast from the new node Ni-x being transferred to the gateway Gi, the encryption key Ki transmitted from the gateway Gi to the management server 101 is newly received from the management server 101 via the portable terminal MT. Node Ni-x can be provided. As a result, the encryption key Ki to be set for the new node Ni-x can be easily acquired, and the efficiency of setting the encryption key Ki used by the new node Ni-x can be improved.

(Example of adding an encryption key to a border node in a network system)
Next, taking a detailed configuration of the network system as an example, an example of adding an encryption key will be specifically described with reference to FIGS.

FIG. 11 is an explanatory diagram (part 1) illustrating an example of adding an encryption key to a boundary node in the network system. In the state (A) of FIG. 11, the management server 101 and the gateway G1 can communicate via the network NW1. In FIG. 11, the ad hoc network A1 includes a gateway G1 and nodes N1-1 to N1-4 and Nx. The gateway G1 and the nodes N1-1 to N1-4 and Nx hold the encryption key K1 unique to the gateway G1 by the downstream type or the upstream type described above.

In the ad hoc network A1, the encrypted packet SP1 encrypted by the transmission source (any one of the gateway G1 and the nodes N1-1 to N1-4 and Nx) with the encryption key K1 is subjected to multihop communication. The nodes N1-1 to N1-4 and Nx that have received the encrypted packet SP1 transfer the encrypted packet SP1 to the neighboring nodes when the encrypted packet SP1 can be decrypted with the encryption key K1, thereby enabling the encrypted packet SP1 multi-hop communication is realized.

FIG. 12 is an explanatory diagram (part 2) showing an example of adding an encryption key to a boundary node in the network system. FIG. 12 shows a state (B) next to the state (A) in FIG. Specifically, the state (B) in FIG. 12 shows a state in which the ad hoc network A2 is installed after the state (A) in FIG. The ad hoc network A2 includes a gateway G2 and nodes N2-1 to N2-3. The gateway G2 and the nodes N2-1 to N2-3 hold the encryption key K2 unique to the gateway G2 by the downstream type or the upstream type described above.

In the ad hoc network A2, the encrypted packet SP2 encrypted by the transmission source (any one of the gateway G2 and the nodes N2-1 to N2-3) with the encryption key K2 is subjected to multihop communication. The nodes N2-1 to N2-3 that have received the encrypted packet SP2 transfer the encrypted packet SP2 to the neighboring nodes when the encrypted packet SP2 can be decrypted with the encryption key K2, so that the encrypted packet SP2 Realize multi-hop communication. Note that the node Nx is a node in the ad hoc network A1, but is within the communication range of the node N2-2 in the ad hoc network A2.

FIG. 13 is an explanatory diagram (part 3) illustrating an example of adding an encryption key to a boundary node in the network system. FIG. 13 shows a state (C) next to the state (B) of FIG.

(1) Since the node Nx is within the communication range of the node N2-2 in the ad hoc network A2, the encrypted packet SP2 from the node N2-2 is intercepted. Since the header of the intercepted encrypted packet SP2 is not encrypted, the node Nx specifies the address of the gateway G2 from the header of the encrypted packet SP2. The encrypted packet SP2 generated by the nodes N2-1 to N2-3 is described with the address of the gateway G2 as the destination.

In the encrypted packet SP2 generated by the gateway G2, the address of the gateway G2 is described as the transmission source, and the broadcast address is described at the destination. Therefore, the address of the gateway G2 can be detected from the transmission source address when the destination of the encrypted packet SP2 is a broadcast address, and from the destination address when the destination of the encrypted packet SP2 is not a broadcast address.

(2) Then, the node Nx counts the number of failures to decrypt the encrypted packet SP2 (number of intercepts) and the number of successes (number of normal receptions) for each detected gateway. The number of failures and successes is counted at regular intervals. In this case, after a certain period of time, the number of failures and the number of successes are reset. Further, the count of the number of failures and the number of successes may be accumulated indefinitely without being separated at a fixed period.

FIG. 14 is an explanatory diagram (part 4) of an example of adding an encryption key to a boundary node in the network system. FIG. 14 shows a state (D) next to the state (C) of FIG. In the state (D), the boundary node Nx transmits the encrypted packet SP1x to the gateway G1 according to the number of failures and the number of successes (at least the number of failures) in the state (C). For example, when the number of failures exceeds a preset threshold value, the boundary node Nx transmits the encrypted packet SP1x to the gateway G1.

In the encrypted packet SP1x, data including the address of the gateway G2 specified in (2) of FIG. 13 and the acquisition request information of the encryption key K2 unique to the gateway G2 is encrypted with the encryption key K1 at the node Nx. It is an encrypted packet. Since the encrypted packet SP1x is subjected to multihop communication within the ad hoc network A1, the encrypted packet SP1x reaches the gateway G1.

When receiving the encrypted packet SP1x from the gateway G1, the management server 101 decrypts the encrypted packet SP1x with the encryption key K1 in the encryption key DB 110. Thereby, the acquisition request information of the address of the gateway G2 and the encryption key K2 unique to the gateway G2 is obtained. When confirming the acquisition request information, the management server 101 extracts the encryption key K2 unique to the gateway G2 from the encryption key DB 110 using the address of the gateway G2 as a clue.

FIG. 15 is an explanatory diagram (part 5) showing an example of adding an encryption key to a boundary node in the network system. FIG. 15 shows a state (E) next to the state (D) of FIG. In the state (E), since the encryption key K2 requested by the node Nx in the state (D) in FIG. 14 is extracted, the management server 101 encrypts the encryption key K2 in the node Nx with the encryption key K1. The encrypted packet SP1 (K2) is transmitted. The encrypted packet SP1 (K2) finally reaches the node Nx via the network NW1 and the gateway G1.

The gateway G1 and nodes N1-1 and N1-3 on the way can also decrypt the encrypted packet SP1 (K2), so that the encryption key K2 can be obtained. However, in order to prevent the overhead of data processing and communication processing, Only the encrypted packet SP1 (K2) is transferred, and the decrypted encryption key K2 is discarded. Specifically, if the destination of the encrypted packet SP1 (K2) (in this case, the address of the node Nx) is not the address of the own node, it may be set to be discarded after the transfer.

FIG. 16 is an explanatory diagram (part 6) of an example of adding an encryption key to a boundary node in the network system. FIG. 16 shows a state (F) next to the state (E) in FIG. In the state (F), since the node Nx has received the encrypted packet SP1 (K2) in the state (E), the node Nx decrypts the encrypted packet SP1 (K2) with the encryption key K1, thereby obtaining the encryption key K2. Take out. Then, the node Nx sets the decrypted encryption key K2 together with the encryption key K1 as an active key that performs encryption and decryption. Thereby, the node Nx can decrypt the encrypted packet SP1 from the node N1-3 with the encryption key K1, and can decrypt the encrypted packet SP2 from the node N2-2 with the encryption key K2. The node Nx can also encrypt the transmitted data with the encryption keys K1 and K2, and transmit the encrypted packets SP1 and SP2.

In this example, since the distance between the node Nx and the node N2-2 is shorter than the distance between the node Nx and the node N1-3, the node Nx preferably communicates via the ad hoc network A2. In such a case, the node Nx may use only the newly added encryption key K2 as an active key and the existing encryption key K1 as an inactive key. Further, in this case, this enables the node Nx to communicate with the ad hoc network A2, thereby improving communication efficiency.

Also, the encryption key K1 set to inactive may be decrypted only for the encrypted packet SP1 that could not be decrypted with the encryption key K2. In this case, the decrypted data is encrypted with the encryption key K2, which is an active key at the node Nx, and distributed as an encrypted packet SP2 in the ad hoc network A2.

As described above, when a new node is set under the boundary node Nx by setting an active key and an inactive key, the new node may include the above-described downstream type (FIGS. 6 to 8) or up-link. Only one encryption key K2, which is an active key, is set instead of both encryption keys K1 and K2 by either one of the stream types (FIGS. 9 and 10). Therefore, since a single key is set for a node installed under the boundary node Nx, the efficiency of data processing and communication processing can be improved.

Also, the inactive encryption key K1 may be deleted at the node Nx. Thereby, the memory saving of the node Nx can be achieved. Furthermore, even if the node Nx is analyzed, only the encryption key K2 is leaked and the encryption key K1 is not leaked, so that security can be improved.

In the following description, “node N” refers to a node that transmits and receives packets by multi-hop communication within any one of the ad hoc networks A1 to An of the network system 100. Further, “nodes and the like” indicate the gateways G1 to Gn and the node N of the network system 100.

(Example of hardware configuration of the management server 101)
FIG. 17 is a block diagram illustrating a hardware configuration example of the management server 101. 17, the management server 101 includes a CPU (Central Processing Unit) 1701, a ROM (Read Only Memory) 1702, a RAM (Random Access Memory) 1703, a magnetic disk drive 1704, a magnetic disk 1705, and an optical disk drive 1706. An optical disk 1707, an I / F (Interface) 1708, a display 1709, a keyboard 1710, and a mouse 1711. Further, the CPU 1701 to the mouse 1711 are connected by a bus 1700, respectively.

Here, the CPU 1701 governs overall control of the management server 101. The ROM 1702 stores a program such as a boot program. The RAM 1703 is used as a work area for the CPU 1701. The magnetic disk drive 1704 controls the reading / writing of the data with respect to the magnetic disk 1705 according to control of CPU1701. The magnetic disk 1705 stores data written under the control of the magnetic disk drive 1704.

The optical disc drive 1706 controls reading / writing of data with respect to the optical disc 1707 according to the control of the CPU 1701. The optical disk 1707 stores data written under the control of the optical disk drive 1706, and causes the computer to read data stored on the optical disk 1707.

The I / F 1708 is connected to the networks NW1 and NW2 through communication lines, and is connected to other devices (for example, the gateway Gi and the mobile terminal MT) via the networks NW1 and NW2. The I / F 1708 controls an internal interface with the networks NW1 and NW2, and controls input / output of data from an external device. For example, a modem or a LAN adapter may be employed as the I / F 1708.

Display 1709 displays data such as a document, an image, and function information as well as a cursor, an icon, or a tool box. As the display 1709, for example, a CRT, a TFT liquid crystal display, a plasma display, or the like can be adopted.

The keyboard 1710 includes keys for inputting characters, numbers, various instructions, etc., and inputs data. Moreover, a touch panel type input pad or a numeric keypad may be used. The mouse 1711 moves the cursor, selects a range, moves the window, changes the size, and the like. A trackball or a joystick may be used as long as they have the same function as a pointing device. Note that the mobile terminal MT can also be realized by the same hardware configuration as that of the management server 101 shown in FIG.

(Example of hardware configuration such as nodes)
FIG. 18 is a block diagram illustrating a hardware configuration example such as a node. In FIG. 18, the node or the like includes a CPU 1801, a RAM 1802, a flash memory 1803, an I / F 1804, and an encryption circuit 1805. The CPU 1801 to the encryption circuit 1805 are connected by a bus 1800, respectively.

Here, the CPU 1801 controls the entire node and the like. The RAM 1802 is used as a work area for the CPU 1801. The flash memory 1803 stores key information such as programs and encryption keys. The I / F 1804 transmits and receives packets by multi-hop communication. Further, the I / F 1804 of the gateway Gi is connected to the network NW1 through a communication line, and is connected to the management server 101 via the network NW1.

The encryption circuit 1805 is a circuit that encrypts data with an encryption key when encrypting the data. When encryption is executed by software, the encryption circuit 1805 is not necessary by storing a program corresponding to the encryption circuit 1805 in the flash memory 1803.

(Storage contents of the encryption key DB 110)
FIG. 19 is an explanatory diagram showing an example of the contents stored in the encryption key DB 110. In FIG. 19, the encryption key DB 110 has fields of ID, GW address, and encryption key, and by setting information in each field, key information 1900-1 to 1900-n for each of the gateways G1 to Gn is used as a record. I remember it.

Here, the ID is an identifier of each gateway Gi used for explanation in this specification. The GW address is the address of the gateway Gi. As the GW address, for example, a MAC (Media Access Control) address or an IP (Internet Protocol) address of the gateway Gi can be used. The encryption key is an encryption key Ki unique to each gateway Gi, and is specifically binary data of about 128 to 256 bits, for example. Taking the key information 1900-1 as an example, the gateway G1's GW address is “xx: xx: xx: xx: 12: 34”, and the encryption key is “encryption key K1”.

In addition, the key information 1900-i has position information Pi and history information Hi. The position information Pi is information indicating the installation position of the gateway Gi. For example, the latitude and longitude, the address of the installation destination of the gateway Gi, etc. are mentioned. The history information Hi is the number of times the setting is canceled after the encryption key Ki unique to the gateway Gi is set to the node N in another ad hoc network Aj (j ≠ i). The setting cancellation includes, for example, a case where it is set to inactive or a case where it is deleted.

Note that the encryption key DB 110 is realized by a storage device such as the ROM 1702, the RAM 1703, the magnetic disk 1705, and the optical disk 1707 of the management server 101 shown in FIG. The storage contents of the encryption key DB 110 may be updated when the management server 101 receives the encryption key Ki unique to the gateway Gi from the gateway Gi. Further, the stored contents of the encryption key DB 110 may be updated by a user operation input using the keyboard 1710 and the mouse 1711 shown in FIG.

(Example of functional configuration of node N)
FIG. 20 is a block diagram illustrating a functional configuration example of the node N. The node N includes a receiving unit 2001, a detecting unit 2002, a decoding unit 2003, a counting unit 2004, a determining unit 2005, a transmitting unit 2006, and a setting unit 2007. Specifically, each function unit (reception unit 2001 to setting unit 2007), for example, causes the CPU 1801 to execute a program stored in a storage device such as the RAM 1802 and the flash memory 1803 illustrated in FIG. The function is realized by the I / F 1804. Further, the processing results of the respective function units (reception unit 2001 to setting unit 2007) are stored in a storage device such as the RAM 1802 and the flash memory 1803 unless otherwise specified.

The receiving unit 2001 receives an encrypted packet. Specifically, the node N receives the encrypted packet regardless of whether or not the node N can be decrypted with the encryption key Ki of the node N. When a packet that cannot be decrypted with the encryption key Ki is received, the encrypted packet is intercepted.

The detection unit 2002 detects the destination of the encrypted packet received by the reception unit 2001 or the gateway serving as the transmission source for each encrypted packet. The encrypted packet is encrypted with one of the encryption keys Ki, but the header portion is not encrypted. Here, the data structure of the encrypted packet will be described.

21 and 22 are explanatory diagrams showing an example of the data structure of the encrypted packet Ki encrypted with the encryption key Ki. FIG. 21 shows an example of the data structure of the encrypted packet SP1 broadcast from the gateway G1 as an example. FIG. 22 shows an example of the data structure of an encrypted packet SP1 from a certain node N to the gateway G1 as an example.

21 and 22, the encrypted packet SPi has a header part 2110 and a payload part 2120. In the header part 2110, a destination address, a source address, and the number of hops are described. The payload portion 2120 describes the encrypted data body (hatched portion in FIG. 20). Here, the destination address is a destination address. The sending address is a sender address. Note that although the MAC address is used as an example of the destination address, the sending address, and the GW address here, an IP address or the like may be used.

The number of hops is a remaining transfer count indicating how many times the encrypted packet SPi is transferred. The maximum number of hops of the encrypted packet SPi broadcast from the gateway Gi is set in advance. The hop number is decremented when the encrypted packet SPi is transferred, and the encrypted packet SPi having the hop number of “0” is discarded. Here, the hop number “10” of the encrypted packet SP1 is described.

In FIG. 21, since the encrypted packet SPi is a broadcast packet from the gateway Gi as the destination address, the broadcast MAC address “00: 00: 00: 00: 00” is described in the destination address. In addition, the MAC address “xx: xx: xx: xx: 12: 34” of the gateway G1 that is the broadcast source is described as the source address.

In FIG. 22, the MAC address “xx: xx: xx: xx: 12: 34” of the gateway G1 is described as the destination address for sending to the gateway G1. Further, the MAC address “AA: BB: CC: DD: CC: DD” of the transmission source node is described as the source address.

Returning to FIG. 20, when the destination address of the encrypted packet SPi is a broadcast address, the detection unit 2002 detects the address described in the source address as the address of the gateway Gi because the source address is the address of the gateway Gi. To do. When the destination address of the encrypted packet SPi is a broadcast address, the destination address is detected as the address of the gateway Gi because it is the encrypted packet SPi from the node N to the gateway Gi. Therefore, the MAC address “xx: xx: xx: xx: 12: 34” of the gateway G1 can be detected in any of the encrypted packets SPi in FIG. 21 and FIG.

The decryption unit 2003 decrypts the encrypted packet received by the reception unit 2001 with the stored encryption key Ki. When there are a plurality of encryption keys Ki, the decryption unit 2003 may decrypt the brute force, or may terminate the decryption when the brute force is being decrypted or decrypted. In addition, the decryption unit 2003 may decrypt only the active encryption key Ki. Note that if any encryption key Ki cannot be decrypted, the encrypted packet SPi is intercepted.

The counting unit 2004 counts the number of failures in which the encrypted packet SPj (j ≠ i) could not be decrypted with the encryption key Ki for each gateway Gi detected by the detecting unit 2002. For example, in the node N to which the encryption key Ki is set, an attempt to decrypt the encrypted packet SPj in which the address of the gateway Gj is described with the encryption key Ki will fail. As a result, the number of failures for the gateway Gj is counted as one. The counting result is recorded in a table described later. In addition, it is good also as counting by accumulating the encryption packet SPi which failed in decoding.

In addition, the counting unit 2004 counts the number of successes that the encrypted packet SPi can be decrypted with the encryption key Ki for each gateway Gi detected by the detecting unit 2002. For example, in the node N in which the encryption key Ki is set, the encryption packet SPi in which the address of the gateway Gi is described is successfully decrypted with the encryption key Ki. As a result, the number of successes for the gateway Gi is counted by one. Also in this case, the counting result is recorded in a table to be described later. It is also possible to count by accumulating encrypted packets SPi that have been successfully decrypted. Note that the counting by the counting unit 2004 may be performed at regular intervals, or may be performed until the threshold value is reached.

Whether or not the determination unit 2005 should acquire the encryption key Kj unique to the gateway Gj (j ≠ i) other than the affiliated gateway Gi having the node as a subordinate node based on the counting result counted by the counting unit 2004. Judging.

Specifically, for example, the determination unit 2005 determines for each gateway whether or not the number of failures is greater than or equal to a threshold value related to key acquisition. The threshold related to key acquisition is, for example, the upper limit of the number of decryption failures for each gateway Gi within a certain period. As an example, assume 1000 times.

For example, in the node N in which the encryption key Ki unique to the gateway Gi is set, the number of decryption failures with the encryption key Ki of the encrypted packet SPj in which the address of the gateway Gj is described is 1584 times within a certain period. To do. In this case, with the encryption key Ki unique to the gateway Gi, the decryption process is wasted only by intercepting the encrypted packet SPj. Therefore, the determination unit 2005 determines that the encryption key Kj unique to the gateway Gj should be acquired. As described above, the determination unit 2005 can determine whether or not a key should be acquired by using an absolute index called a threshold related to key acquisition.

Further, the determination unit 2005 may determine for each gateway Gi whether or not a difference obtained by subtracting the number of successes from the number of failures counted by the counting unit 2004 is equal to or greater than a threshold value related to key acquisition. Specifically, for example, the determination unit 2005 determines the encrypted packet SPi in which the address of the gateway Gi is described based on the number of failure of decryption with the encryption key Ki of the encrypted packet SPj in which the address of the gateway Gj is described. The difference obtained by subtracting the number of successful decryptions with the encryption key Ki is obtained.

The determination unit 2005 determines that the encryption key Kj unique to the gateway Gj should be acquired based on whether or not the difference is equal to or greater than a threshold value related to key acquisition (for example, 500 times). As described above, the determination unit 2005 can determine whether or not a key should be acquired by using a relative index called a difference obtained by subtracting the number of successes from the number of failures.

The transmission unit 2006 sends the acquisition request for the second key specific to the gateway, which is determined to be equal to or greater than the threshold by the determination unit 2005, to any one of the ad hoc networks in the server storing the key specific to each gateway of the plurality of ad hoc networks. Send via. Specifically, for example, when the determining unit 2005 determines that the threshold value for key acquisition is equal to or greater than the threshold value, the transmitting unit 2006 sends an acquisition request for the encryption key Kj unique to the gateway Gj to the management server 101 via the gateway Gi. Send. Here, the acquisition request will be described.

FIG. 23 is an explanatory diagram showing an example of the data structure of the acquisition request packet. In FIG. 23, the address of the gateway Gi under its node N is described in the destination address of the header part 2310 of the acquisition request packet Pix. In FIG. 23, the MAC address “xx: xx: xx: xx: 12: 34” of the gateway G1 under the node N is described. In addition, the MAC address “AA: BB: CC: DD: CC: DD” of the source node N is described in the source address.

In the payload portion 2320, the key acquisition request flag and the gateway address detected by the detection portion 2002, that is, the address of the gateway Gj described in the encrypted packet SPj that could not be decrypted with the encryption key Ki of the node N are stored. is described. In FIG. 23, the MAC address “xx: xx: xx: xx: 56: 78” of the gateway G2 is described. The acquisition request packet Pix becomes an encrypted acquisition request packet SPix by encrypting the payload portion 2320 with the encryption key Ki. In FIG. 23, the acquisition request packet P1x is encrypted into an encrypted acquisition request packet SP1x.

Referring back to FIG. 20, thereafter, the receiving unit 2001 receives an encryption response packet for the encryption acquisition request packet SPix from the management server 101 via the gateway Gi. The encryption response packet includes the encryption key Kj encrypted with the encryption key Ki. The received encryption response packet is decrypted with the encryption key Ki by the decryption unit 2003, whereby the encryption key Kj is extracted.

The setting unit 2007 sets the encryption key Kj as a key for performing encryption and decryption. Specifically, for example, an active key is set in the same manner as the encryption key Ki. As a result, when the node N subsequently becomes the boundary node Nx, encryption and decryption can be performed using both the encryption keys Ki and Kj. Therefore, communication processing can be performed using both gateways Gi and Gj of the ad hoc networks Ai and Aj. Thereby, even if a communication failure occurs with one of the ad hoc networks, communication can be performed via the other ad hoc network.

In addition, when the newly added encryption key Kj is set as a key for performing encryption and decryption, the setting unit 2007 may set the existing encryption key Ki as a key that is not subjected to encryption and decryption. Specifically, for example, when a new encryption key Kj is added, the setting of the existing encryption key Ki may be canceled, that is, deactivated. As a result, at the boundary node Nx, encryption and decryption are performed using the encryption key Kj, which is assumed to have a greater number of decryptions than the encryption key Ki, as an active key.

On the other hand, since the encryption key Ki is set inactive, it is not used for encryption and decryption. Thereby, useless data processing and communication processing can be reduced. Further, the encryption key Ki set to inactive may be deleted. Thereby, the memory saving of the boundary node Nx can be achieved.

Also, the newly added encryption key Kj may be used as the main key, and the existing encryption key Ki may be used as the sub key. Here, the primary key is the above-described active key, and the secondary key is a key that becomes active only under a certain restriction. For example, it is a key that can be decrypted when the primary key cannot be decrypted. As a result, when the encrypted packet SPi is received, it cannot be decrypted with the encryption key Kj that is the primary key, and is decrypted with the encryption key Ki that is the secondary key. The decrypted data is encrypted with the encryption key Kj and transferred as an encrypted packet SPj.

As described above, when a new node is newly set up under the boundary node Nx by setting the main and sub keys, the new node may include the downstream type (FIGS. 6 to 8) or the upstream described above. Regardless of the setting method of the type (FIGS. 9 and 10), only the encryption key Kj as the main key is set. Therefore, it is possible to prevent an increase in overhead of data processing and communication in the new subordinate node.

(Storage contents of management table in node N)
Next, the contents stored in the management table of node N will be described. The management table realizes its function by the RAM 1802 or the flash memory 1803 of FIG. The management table manages key information and decryption success / failure information. This will be described below with reference to FIGS.

FIGS. 24 to 26 are explanatory diagrams showing examples of stored contents of the management table in the node N. FIG. 24 to 26, the management table T has key information and decryption success / failure information. The key information includes a gateway address item, an encryption key item, and a valid / invalid flag item. In the gateway address item, the address of the gateway detected by the detection unit 2002 is stored. 24 to 26, for convenience, the gateway code is described instead of the gateway address.

In the encryption key item, an encryption key (or a pointer to the encryption key) is stored. Accordingly, the encryption key not set by the setting unit 2007 is not stored. In the valid / invalid flag item, a flag indicating whether the encryption key is active (valid) or inactive (invalid) is stored. For example, if the flag is “2”, it is active, and if it is “0”, it is inactive. Further, “1” indicates that it is active (subkey) only under certain restrictions.

Here, in FIGS. 24 to 26, (A) shows the storage contents of the management table T in the state shown in FIG. Specifically, the gateway address is the address of the gateway G1, the encryption key is the encryption key K1 unique to the gateway G1, and the valid / invalid flag is “2”. During the period (A), the encrypted packet SP1 has been successfully received and decrypted 500 times. Further, since the encrypted packet other than the encrypted packet SP1 is not intercepted, the number of failures at the gateway G1 is zero.

24 to 26, (B) shows the storage contents of the management table T in the period after (A). Due to the newly established ad hoc network A2, the node Nx intercepts the encrypted packet SP2 from the node N2-2. As a result, when the address of the gateway G2 is detected by the detection unit 2002, the address of the gateway G2 is written in the gateway address item. However, since the encryption key K2 has not yet been acquired at this time, the encryption key item stores the encryption key K1 used for decryption, and the valid / invalid flag item stores “2”.

In this state, when communication is performed as shown in FIG. 13, the number of successful decryptions and the number of failures indicated by the decryption success / failure information are stored. Specifically, for example, the node Nx indicates that the decryption using the encryption key K1 of the encrypted packet SP1 in which the address of the gateway G1 is stored has been successful 481 times. Further, it is indicated that the decryption using the encryption key K1 of the encrypted packet SP2 in which the address of the gateway G2 is stored has failed 1584 times.

(C) shows the state of FIG. 16 after (B). 24 to 26, since the newly added encryption key K2 has already been acquired, the node Nx updates the encryption key item of the record of the gateway G2 from the encryption key K1 to the encryption key K2 by the setting unit 2007. In FIG. 24, since both the valid / invalid flag items are set to “2”, the node Nx activates both encryption keys K1 and K2 by the setting unit 2007.

In FIG. 25, since the node Nx sets the valid / invalid flag item of the encryption key K1 to “0” by the setting unit 2007, the encryption key K1 is not used. In FIG. 26, since the node Nx sets the valid / invalid flag item of the encryption key K1 to “1” by the setting unit 2007, the encryption key K1 is used as a sub key.

(Key setting processing procedure of node N)
Next, the key setting process of the node N will be described. Here, it is assumed that the encryption key Ki has already been set as the node N in the ad hoc network Ai. After that, when the ad hoc network Aj is installed, the key setting processing procedure of the node N that has become the boundary node Nx will be described.

FIG. 27 is a flowchart showing a packet transfer processing procedure of the node N (boundary node Nx). First, the node N waits for the reception of the encrypted packet by the receiving unit 2001 (step S2701: No). When the encrypted packet is received (step S2701: Yes), the node N is received by the detecting unit 2002. The gateway address is detected from the header part 2110 of the encrypted packet (step S2702).

Then, the node N executes a decoding process by the decoding unit 2003 (step S2703). Details of the decoding process (step S2703) will be described with reference to FIG. After the decryption process (step S2703), the node N determines whether or not the received encrypted packet can be decrypted with any encryption key (step S2704).

If the decryption fails (step S2704: NO), the node N discards the received encrypted packet (step S2705), and ends the node N key setting processing procedure. Instead of discarding, the encrypted packet that failed to be decrypted may be stored in the RAM 1802 or the flash memory 1803 for counting.

In addition, in step S2704, when decryption is possible with any encryption key (step S2704: Yes), the node N determines whether the destination of the received encrypted packet is the address (or broadcast address) of the own node. Judgment is made (step S2706). When the destination of the received encrypted packet is the address (or broadcast address) of the own node (step S2706: Yes), the node N executes data processing according to the decrypted data (step S2707) and encrypts it. The packet is transferred (step S2708).

On the other hand, when the destination of the received encrypted packet is not the address (or broadcast address) of the own node (step S2706: No), the node N transfers the encrypted packet without executing the data processing (step S2707). (Step S2708). Thereby, the packet transfer processing procedure of the node N is completed.

FIG. 28 is a flowchart showing a detailed processing procedure of the decoding process (step S2703) shown in FIG. This decryption process (step S2703) is a process executed whenever an encrypted packet is received. Also, in FIG. 28, a process of confirming the success / failure of the decryption using all the active encryption keys currently held by the node N is shown.

28, first, the node N determines whether or not there is an unselected encryption key (step S2801). When there is an unselected encryption key (step S2801: Yes), the node N selects one unselected encryption key (step S2802), and the decryption unit 2003 performs decryption with the selected encryption key (step S2803). ).

If decryption fails (step S2804: No), the node N adds 1 to the number of decryption failures with the selection key for the gateway detected in step S2702 in the management table T by the counting unit 2004. (Step S2805), the process returns to Step S2801. On the other hand, when the decryption is successful (step S2804: Yes), the node N adds 1 to the number of successful decryptions with the selection key for the gateway detected in step S2702 in the management table T by the counting unit 2004. (Step S2806), it returns to step S2801.

On the other hand, in step S2801, if there is no unselected encryption key (step S2801: No), the process proceeds to step S2704. Thereby, the decoding process (step S2703) is terminated. According to the decryption process (step S2703) shown in FIG. 28, it is possible to attempt decryption using all the active encryption keys held by the brute force. Therefore, the counting unit 2004 can obtain an accurate counting result.

FIG. 29 is a flowchart showing a detailed processing procedure of the decoding process (step S2703) shown in FIG. This decryption process (step S2703) is a process executed whenever an encrypted packet is received. In FIG. 29, the success or failure of the decryption is confirmed using all the active encryption keys currently held by the node N, but the process ends when the decryption is successful. Note that the same processing as that in FIG. 28 is denoted by the same step number, and description thereof is omitted.

The difference from FIG. 28 is that, in step S2806, when the node N adds 1 to the number of successful decryptions with the selection key for the gateway detected in step S2702 by the counting unit 2004 (step S2806), the process proceeds to step S2704. It is a point to shift. That is, when the decoding is successful, the decoding process (step S2703) ends. As a result, it is not necessary to continue the decoding process (step S2703) even after the decoding is successful, so that the decoding process of the node N (step S2703) can be speeded up.

Next, the encryption key addition process of node N will be described. FIG. 30 shows an encryption key addition process procedure in absolute evaluation based on the number of failures and a threshold value related to key acquisition. On the other hand, FIG. 31 shows an encryption key addition processing procedure in relative evaluation based on a difference obtained by subtracting the number of successes from the number of failures.

FIG. 30 is a flowchart (part 1) illustrating the encryption key addition processing procedure of the node N. In FIG. 30, first, the node N waits for a predetermined period to elapse (step S3001: No). If the predetermined period elapses (step S3001: Yes), the node N refers to the management table T, The determination unit 2005 determines whether there is a gateway (hereinafter, “specific gateway”) in which the number of failures is greater than or equal to a threshold value related to key acquisition (step S3002).

If there is no specific gateway whose number of failures is equal to or greater than the threshold for key acquisition (step S3002: No), the process proceeds to step S3009. On the other hand, when there is a specific gateway in which the number of failures is equal to or greater than the threshold for key acquisition (step S3002: Yes), the node N sends a request for acquiring an encryption key unique to the specific gateway to the management server 101 by the transmission unit 2006 Transmit (step S3003).

Thereafter, an encrypted packet is awaited from the management server 101 (step S3004). If the key has not been received (step S3004: NO), the node N determines whether or not a timeout has occurred (step S3005). When it is not time-out (step S3005: No), it returns to step S3004. In the case of timeout (step S3005: Yes), the process proceeds to step S3009.

On the other hand, when the encrypted packet is received in step S3004 (step S3004: Yes), the node N is decrypted by the decryption unit 2003 with the held encryption key (step S3006). Then, the node N determines whether or not there is a provision permission flag in the decrypted data (step S3007). When there is a provision permission flag (step S3007: Yes), since the decrypted data includes the encryption key, the node N sets the encryption key obtained by the decryption as an active key by the setting unit 2007. (Step S3008).

On the other hand, when it is a notification that provision is not possible (step S3007: No), the process proceeds to step S3009. In step S3009, the node N resets the decryption success / failure information in the management table T (step S3009). Thereby, the encryption key adding process of the node N is finished.

FIG. 31 is a flowchart (part 2) illustrating the encryption key addition processing procedure of the node N. In FIG. 31, the same processes as those in FIG. 30 are denoted by the same step numbers, and description thereof is omitted. The difference from FIG. 30 is that step S3002 of FIG. 30 is changed to S3102. In FIG. 31, in order to perform relative evaluation, the determination unit 2005 determines whether or not there is a gateway Gi whose difference obtained by subtracting the number of successes from the number of failures counted by the counting unit 2004 is equal to or greater than a threshold value related to key acquisition. Become. In this way, in FIG. 31, since it can be relatively determined which ad hoc network is more likely to succeed in decoding, there is an advantage that communication efficiency is easily superior or inferior. Next, a functional configuration example of the management server 101 will be described.

FIG. 32 is a block diagram illustrating a functional configuration example of the management server 101. 32, the management server 101 includes a receiving unit 3201, a decrypting unit 3202, a determining unit 3203, an extracting unit 3204, an encryption processing unit 3205, and a transmitting unit 3206. Specifically, each functional unit (reception unit 3201 to transmission unit 3206) stores a program stored in a storage device such as the ROM 1702, the RAM 1703, the magnetic disk 1705, or the optical disk 1707 of the management server 101 shown in FIG. The function is realized by causing the CPU 1701 to execute or by the I / F 1708.

Further, unless otherwise specified, the processing results of the functional units (reception unit 3201 to transmission unit 3206) are storage devices such as the ROM 1702, the RAM 1703, the magnetic disk 1705, and the optical disk 1707 of the management server 101 shown in FIG. Is remembered.

The receiving unit 3201 receives the encrypted packet SPi from each gateway Gi. Specifically, for example, the reception unit 3201 receives the encrypted packet SPi that has been subjected to multi-hop communication from the node N, from the gateway Gi that controls the node N.

The decryption unit 3202 decrypts the encrypted packet SPi received by the reception unit 3201. Specifically, for example, the encryption key Ki of the encryption key DB 110 is attempted to be brute-forced. Alternatively, the encryption key Ki (the encryption key K1 in the case of FIG. 33) may be extracted from the encryption DB 110 and decrypted using the source address of the encrypted packet SPi as a clue. If the decryption is successful and the payload part 2320 has an acquisition request flag, the encrypted packet SPi is determined to be the encrypted acquisition request packet SPix.

FIG. 33 is an explanatory diagram showing an example of decryption of the encrypted acquisition request packet SPix. The address “xx: xx: xx: xx: xx: xx” of the management server 101 is described in the destination address of the header part 2310 of the encrypted acquisition request packet SPix. In addition, the address of the gateway Gi (G1 in FIG. 33) serving as a transmission source is described in the source address. In addition, the address of the acquisition request source node N is added to the header portion 2310 by the gateway Gi. In FIG. 33, the MAC address “AA: BB: CC: DD: CC: DD” of the node N is described.

The management server 101 extracts the encryption key Ki (in the case of FIG. 33, the encryption key K1) from the encryption DB 110 using the source address as a clue. As a result, the encrypted acquisition request packet SPix can be decrypted. In FIG. 33, since the decryption was successful with the encryption key K1, the acquisition request flag can be extracted from the payload portion 2320 of the acquisition request packet Pix.

32, the determination unit 3203 determines whether the received packet is an acquisition request packet Pix. Specifically, the determination unit 3203 determines that it is an acquisition request packet Pix when the decryption unit 3202 can confirm the acquisition request flag.

Further, the determination unit 3203 determines whether or not the encryption key Kj requested for acquisition should be transmitted to the node N that is the acquisition request source based on a predetermined determination criterion. Specifically, for example, the distance between the position information Pi of the gateway Gi that uses the encryption key Ki stored in the encryption key DB 110 and the position information Pj of the gateway Gj that uses the requested encryption key Kj is acceptable. The determination unit 3203 determines whether or not it is within the range. When it is within the allowable range, the determination unit 3203 determines that transmission should be performed to the node N that is the acquisition request source.

Also, the determination unit 3203 determines whether or not to transmit to the node N that is the acquisition request source, based on the history information Hj of the gateway Gj that uses the encryption key Kj that is the acquisition request target. Specifically, for example, the determination unit 3203 refers to the history information Hj of the address of the gateway Gj described in the payload portion 2320 of the acquisition request packet Pix decoded by the reception unit 3201.

FIG. 34 is an explanatory diagram showing a specific example of the history information Hj. The history information Hj stores the number of times the setting of the encryption key Kj is canceled when the encryption key Kj is set together with another encryption key Ki. The number of setting cancellations is the number of times set to inactive. Moreover, the number of times of deletion or the number of times of becoming a sub key may be used. It is assumed that the history information Hj is updated by transmitting the presence / absence of setting cancellation from the node N each time.

Here, in FIG. 34, the number of setting cancellation times of the encryption key Kj when set together with the encryption key Ki is “7”. For example, when the threshold value related to the cancellation of setting is “10”, the determination unit 3203 determines that the encryption key Kj should be transmitted because the threshold value is lower than the threshold value related to the cancellation of setting. On the other hand, when the threshold value related to the setting cancellation is “5”, for example, it becomes larger than the threshold value related to the setting cancellation, so the determination unit 3203 determines that the encryption key Kj should not be transmitted. In addition, when the acquisition request of the encryption key Kj from the node N in the ad hoc network Ai is made for the first time, the encryption key Kj should be transmitted because the encryption key Kj setting release count for the encryption key Ki is zero. Determined.

The extraction unit 3204 extracts the encryption key Kj to be acquired from the encryption key DB 110. Specifically, for example, the extraction unit 3204 extracts the encryption key Kj associated with the address of the gateway Gj described in the header part 2310 of the acquisition request packet Pix from the encryption key DB 110.

The encryption processing unit 3205 encrypts the encryption key Kj extracted from the encryption DB 110 with the encryption key Ki that has successfully decrypted the encryption acquisition request packet SPix, and transmits an encryption response packet.

FIG. 35 is an explanatory diagram showing an example of the data structure of the response packet. The destination address of the header part 3510 of the response packet Rix describes the source address of the encrypted acquisition request packet SPix. In FIG. 35, the address of the gateway G1 is described. The address of the management server 101 is described in the sender address.

In the payload portion 3520, a provision permission / non-permission flag for the encryption key Kj is described. Specifically, the provision permission flag is set when the determination unit 3203 determines that transmission should be performed, and the provision non-permission flag is set when it is determined that transmission should not be performed. If the provision permission flag is set, the encryption key Kj extracted by the extraction unit 3204 is described. In FIG. 35, the encryption key K2 is described.

In the payload portion 3520, the address of the acquisition request source is described. In FIG. 35, the MAC address “AA: BB: CC: DD: CC: DD” of the node N (Nx) as the acquisition request source is described. The response packet Rix is encrypted by the encryption processing unit 3205 with the encryption key Ki that has successfully decrypted the encryption acquisition request packet SPix. In FIG. 35, encryption is performed using the encryption key K1. Thereby, the encryption response packet SRix is generated.

The transmission unit 3206 transmits the encryption response packet SRix. The encrypted response packet SRix is transmitted to the destination gateway Gi. The gateway Gi replaces the source address of the encrypted response packet SRix with the address of the gateway Gi, and replaces the destination address with the broadcast address. Thereby, the encryption response packet SRix is transmitted to the ad hoc network Ai.

In the node N, the encryption response packet SRix is decrypted with the encryption key Ki, and if there is a provision permission flag (step S3007: Yes), the encryption key Kj described in the payload portion 3520 is set to be active. become. On the other hand, if it is a provision non-permission flag (step S3007: No), since the encryption key Kj is not described, the encryption key Kj is not set.

(Key providing procedure of management server 101)
FIG. 36 is a flowchart (part 1) illustrating the key provision processing procedure of the management server 101. FIG. 36 shows a processing procedure that does not use the position information Pi and the history information Hj. First, the management server 101 waits for reception of an encrypted packet (step S3601: No). When an encrypted packet is received (step S3601: Yes), the management server 101 executes decryption processing by the decryption unit 3202. (Step S3602). Details of the decoding process (step S3602) will be described with reference to FIG.

Thereafter, when the decryption is successful, the management server 101 determines whether or not the decrypted packet has an acquisition request flag by the determination unit 3203 (step S3603). When there is no acquisition request flag (step S3603: No), the management server 101 executes data processing according to the payload portion 2120 (step S3604). As a result, the key providing process ends.

On the other hand, if it is an acquisition request flag (step S3603: Yes), it is determined that the packet is an acquisition request packet Pix. Therefore, the management server 101 uses the extraction unit 3204 to extract the encryption key Kj that is the acquisition request target (step S3605). Then, the management server 101 generates an encrypted response packet SRix by encrypting the extracted encryption key Kj with the encryption key Ki decrypted in the decryption process (step S3602) by the encryption processing unit 3205. (Step S3606). Thereafter, the management server 101 transmits the encryption response packet SRix including the encryption key Kj by the transmission unit 3206 (step S3607). As a result, the key providing process ends.

FIG. 37 is a flowchart showing a detailed processing procedure of the decoding process (step S3602) shown in FIG. First, “i” of the gateway Gi is initialized with “i = 1” (step S3701). Then, the encrypted packet SPi received in step S3601 is decrypted using the encryption key Ki unique to the gateway Gi in the encryption key DB 110 (step S3702).

Thereafter, it is determined whether or not the encrypted packet SPi has been successfully decrypted (step S3703). If the decryption of the encrypted packet SPi is successful (step S3703: YES), the process proceeds to step S3603 shown in FIG.

On the other hand, when the decryption of the encrypted packet SPi fails (step S3703: No), “i” of the gateway Gi is incremented (step S3704), and it is determined whether “i” is larger than “n” (step S3704). Step S3705).

Here, when “i” is equal to or less than “n” (step S3705: No), the process returns to step S3702. On the other hand, if “i” is greater than “n” (step S3705: YES), error processing is executed (step S3706), and a series of processing of the management server 101 is terminated. As a result, the encrypted packet SPi can be decrypted.

FIG. 38 is a flowchart (part 2) illustrating the key provision processing procedure of the management server 101. FIG. 36 shows a processing procedure using the position information Pi and / or history information Hj. Note that the same steps as those in FIG. 36 are denoted by the same step numbers and description thereof is omitted. The difference from FIG. 36 is that a validity determination process (step S3800) is added between step S3603: YES and step S3605. Details of the validity determination process (step S3800) will be described below with reference to FIGS.

FIG. 39 is a flowchart (part 1) showing a detailed processing procedure of the validity determination processing (step S3800). FIG. 39 shows a processing procedure using the position information Pi. First, the management server 101 uses the extraction unit 3204 to transmit the location information Pi of the gateway Gi that transmitted the encrypted acquisition request packet SPix, and the location information Pj of the gateway Gj whose address is described in the payload portion 2320 of the acquisition request packet Pix. Is extracted (step S3901).

Next, the management server 101 determines whether the distance between the position information Pi and Pj is within an allowable range by the determination unit 3203 (step S3902). If it is within the allowable range (step S3902: YES), the process proceeds to step S3605 in FIG.

On the other hand, when it is outside the allowable range (step S3902: No), the management server 101 transmits the encryption response packet SRix including the provision non-permission flag by the encryption processing unit 3205 and the transmission unit 3206 (step S3903). Thus, the encryption key Kj can be provided only when the distance between the gateways Gi and Gj is guaranteed to be a short distance.

FIG. 40 is a flowchart (part 2) showing a detailed processing procedure of the validity determination processing (step S3800). FIG. 40 shows a processing procedure using the history information Hj. First, the management server 101 extracts the history information Hj of the gateway Gj whose address is described in the payload portion 2320 of the acquisition request packet Pix by the extraction unit 3204 (step S4001).

Next, the management server 101 uses the determination unit 3203 to determine whether or not the number of setting cancellations in the history information Hj is within an allowable range (step S4002). If it is within the allowable range (less than the threshold value related to the setting cancellation) (step S4002: Yes), the process proceeds to step S3605 in FIG.

On the other hand, if it is out of the allowable range (more than the threshold for setting cancellation) (step S4002: No), the management server 101 uses the encryption processing unit 3205 and the transmission unit 3206 to encrypt the response packet including the provision non-permission flag SRix is transmitted (step S4003). Thereby, even if the encryption key Kj is provided, it is not necessary to provide the encryption key Kj to the node N that may be reset again, so that unnecessary key addition setting processing can be prevented. .

FIG. 41 is a flowchart (part 3) showing a detailed processing procedure of the validity determination processing (step S3800). FIG. 41 shows a processing procedure using the position information Pi and the history information Hj. First, the management server 101 extracts the location information Pi of the gateway Gi that transmitted the acquisition request packet Pix and the location information Pj of the gateway Gj whose address is described in the payload portion 2320 of the acquisition request packet Pix by the extraction unit 3204. (Step S4101).

Next, the management server 101 determines whether the distance between the position information Pi and Pj is within an allowable range by the determination unit 3203 (step S4102). When it is within the allowable range (step S4102: Yes), the management server 101 extracts the history information Hj of the gateway Gj whose address is described in the payload part 2320 of the acquisition request packet Pix by the extraction unit 3204 (step S4103). ).

Next, the management server 101 uses the determination unit 3203 to determine whether or not the number of setting cancellations in the history information Hj is within an allowable range (step S4104). If it is within the allowable range (less than the threshold value related to the setting cancellation) (step S4104: YES), the process proceeds to step S3605 in FIG.

In step S4102, if it is outside the allowable range (step S4102: No), the management server 101 transmits the encryption response packet SRix including the provision non-permission flag by the encryption processing unit 3205 and the transmission unit 3206 ( Step S4105). Thereby, the encryption key Kj can be provided only when the distance between the gateways Gi and Gj is guaranteed to be a short distance.

In step S4104, if it is out of the allowable range (more than the threshold for setting cancellation) (step S4104: No), the management server 101 includes the provision non-permission flag by the encryption processing unit 3205 and the transmission unit 3206. The encrypted response packet SRix is transmitted (step S4105). Thereby, even if the encryption key Kj is provided, it is not necessary to provide the encryption key Kj to the node N that may be reset again, so that useless key addition setting processing can be prevented. .

(Example of canceling encryption key setting)
Next, an example of canceling the encryption key setting will be described. In the example described above, a plurality of encryption keys may be set as active keys at the boundary node Nx. In such a case, the setting can be canceled according to the subsequent situation.

42 and 43 are explanatory diagrams showing examples of updating the management table T of the node N. FIG. 42 and 43 show states after the state (C) in FIG. In FIG. 42, the number of successes of the encryption key K1 is 509 times and the number of failures is 1083 times. The encryption key K2 is reversed. When the threshold value regarding the setting cancellation of the number of failures is 1000 times, since the encryption key K1 has failed more than the threshold value regarding the setting cancellation, the valid / invalid flag is updated to “0”. As a result, the encryption key K1 becomes inactive, and thereafter encryption and decryption are performed using only the encryption key K2.

In FIG. 43, the valid / invalid flag is updated to “1”. As a result, the encryption key K1 becomes active only under certain restrictions, and the encryption key K1 is used for decryption only when it cannot be decrypted with the encryption key K2.

FIG. 44 is a flowchart (part 1) showing the key setting release processing procedure of the node N. First, the node N waits for a predetermined period to elapse (step S4401: No), and if the predetermined period elapses (step S4401: Yes), the node N determines that the success number is a threshold value for canceling the setting by the determination unit 2005. It is determined whether or not there is an encryption key (hereinafter, “specific key”) (step S4402). When there is no specific key (step S4402: No), it transfers to step S4407.

On the other hand, when it is a specific key (step S4402: Yes), the node N determines whether or not both are equal to or less than a threshold value related to setting cancellation (step S4403). If none of them is equal to or less than the threshold value related to the setting cancellation (step S4403: No), the node N sets the specific key as an inactive key by the setting unit 2007 (step S4404).

On the other hand, if both are less than or equal to the threshold for canceling the setting (step S4403: YES), the node N sets the specific key with the smallest number of successes as an inactive key by the setting unit 2007 (step S4405).

Then, after step S4404 and S4405, the node N transmits a setting cancellation result to the management server 101 (step S4406). Thereafter, the node N resets the decryption success / failure information of the management table T (step S4407). Thereby, the key setting cancellation processing procedure of the node N is completed. Thereby, when it is below the threshold value regarding the cancellation | release which causes trouble in communication, it can set to inactive.

If both are below the threshold for canceling the setting, only the specific key with the relatively smallest number of successes is set as an inactive key. The ad hoc network encryption key can be set inactive.

Note that if an inactive setting is made, the encryption key may be deleted or a sub key may be used. In particular, if a certain period of success number 0 continues several times, there is a high possibility that it has been removed. In such a case, even if an inactive key is held, it is useless and is deleted. Thereby, the memory saving of the node N can be achieved.

FIG. 45 is a flowchart (part 2) showing the key setting release processing procedure of the node N. First, the node N waits for a predetermined period to elapse (step S4501: No), and when the predetermined period elapses (step S4501: Yes), the node N sets the specific key with the smallest number of successes by the setting unit 2007. An active key is set (step S4502).

Then, the node N transmits the setting cancellation result to the management server 101 (step S4503). Thereafter, the node N resets the decryption success / failure information in the management table T (step S4504). Thereby, the key setting cancellation processing procedure of the node N is completed. Thereby, an inactive key can be set by relative evaluation of the number of successes.

In other words, since only the specific key with the relatively smallest number of successes is set as an inactive key, the encryption key of the ad hoc network with the lower communication efficiency is set inactive as viewed from the border node Nx. Can do.

Also, when inactive settings are made, the encryption key may be deleted or used as a sub key. In particular, if a certain period of success number 0 continues several times, there is a high possibility that it has been removed. In such a case, even if an inactive key is held, it is useless and is deleted. Thereby, the memory saving of the node N can be achieved.

As described above, according to the present embodiment, when a node N of another ad hoc network Aj is installed in the communication area of the node N in the ad hoc network Ai, the node N in the ad hoc network Ai is subsequently installed. Becomes the boundary node Nx. In this case, the boundary node Nx can autonomously set the encryption key Kj even if the worker OP does not go to the site for setting work of the encryption key Kj in another ad hoc network. Therefore, the efficiency of new addition work can be improved.

In addition, when the encryption key Kj is newly added to the boundary node Nx in which the encryption key Ki is set, if communication efficiency with the node N of the other ad hoc network Aj is better, the communication in the other ad hoc network Aj A gateway Gj can be selected. Therefore, the ad hoc networks Ai and Aj can be autonomously selected, and robustness can be improved.

Also, when the encryption key Kj is newly added, the existing encryption key Ki can be set as an inactive key. As a result, multihop communication can be performed using only the encryption key Kj having the higher communication efficiency, and wasteful packet communication can be reduced.

Further, inactive keys may be deleted at the node Nx. Thereby, the memory saving of the node Nx can be achieved.

In addition, by setting only one active key, for the new node installed under the boundary node Nx, when performing the key setting work in the downstream type or the upstream type described above, only the active key is set. can do. As a result, a plurality of keys are not set in the new subordinate node, and therefore it is possible to prevent an increase in data processing and communication volume when a plurality of encryption keys are used.

In addition, after the fact, one of the plurality of ad hoc networks Ai, Aj to which the boundary node Nx belongs may be removed. Even in such a case, by counting the number of decryption failures, it becomes clear that the removed encryption key Kj is unnecessary, so by setting it to an inactive key, wasteful data processing and communication An increase in the amount can be prevented. When the number of successes for a certain period (or continuous period) is 0, the encryption key set as inactive may be deleted as having been removed. Thereby, the memory saving of the node Nx can be achieved.

2001 receiving unit 2002 detecting unit 2003 decrypting unit 2004 counting unit 2005 determining unit 2006 transmitting unit 3201 receiving unit 3202 decrypting unit 3203 determining unit 3204 extracting unit 3205 encryption processing unit 3206 transmitting unit 110 encryption key DB
T management table

Claims

A node in any one of the plurality of ad hoc networks that performs encryption and decryption with a gateway-specific first key in any one of the ad hoc networks;
A detection step of detecting, for each encrypted packet, a gateway that is a destination or source of the received encrypted packet;
A counting step of counting, for each gateway detected by the detection step, the number of failures in which the encrypted packet could not be decrypted with the first key;
A determination step of determining, for each gateway, whether or not the number of failures counted by the counting step is equal to or greater than a threshold value related to key acquisition;
The acquisition request for the second key specific to the gateway determined to be equal to or greater than the threshold value in the determination step is sent to the server storing the key specific to each gateway of the plurality of ad hoc networks via any one of the ad hoc networks. A transmission process to transmit;
A reception step of receiving the second key stored in the server as a result of the acquisition request being transmitted by the transmission step from the server via any one of the ad hoc networks;
A setting step of setting the second key received by the receiving step as a key for performing encryption and decryption;
The key setting method characterized by performing.
A node in any one of the plurality of ad hoc networks that performs encryption and decryption with a gateway-specific first key in any one of the ad hoc networks;
A detection step of detecting, for each encrypted packet, a gateway that is a destination or source of the received encrypted packet;
The number of successes in which the encrypted packet could be decrypted with the first key is counted for each gateway detected by the detection step, and the number of failures in which the encrypted packet could not be decrypted with the first key. Counting step for each gateway;
A determination step of determining, for each gateway, whether or not a difference obtained by subtracting the number of successes from the number of failures counted by the counting step is greater than or equal to a threshold value related to key acquisition;
The acquisition request for the second key specific to the gateway determined to be equal to or greater than the threshold value in the determination step is sent to the server storing the key specific to each gateway of the plurality of ad hoc networks via any one of the ad hoc networks. A transmission process to transmit;
A reception step of receiving the second key stored in the server as a result of the acquisition request being transmitted by the transmission step from the server via any one of the ad hoc networks;
A setting step of setting the second key received by the receiving step as a key for performing encryption and decryption;
The key setting method characterized by performing.
As a result of the acquisition request being transmitted by the transmission step, executing a decryption step of decrypting the encrypted packet obtained by encrypting the second key in the server with the first key with the first key;
The setting step includes
3. The key setting method according to claim 1, wherein the second key decrypted in the decrypting step is set as a key for performing the encryption and decryption.
The setting step includes
3. The key setting according to claim 1, wherein when the second key is set as a key that performs encryption and decryption, the first key is set as a key that does not perform encryption and decryption. 4. Method.
The setting step includes
3. The key setting method according to claim 1, wherein when the second key is set as a key for performing encryption and decryption, the first key is deleted.
The setting step includes
When the second key is set as a key for encryption and decryption, the first key is set as a key for encryption and decryption only when the second key cannot be decrypted. The key setting method according to claim 1 or 2, characterized in that:
The counting step includes
The number of successes after setting the second key that was able to decrypt the encrypted packet received after the second key was set by the setting step is determined for each of the first key and the second key. Counting about
The determination step includes
It is determined for each of the first key and the second key whether the number of successes after setting the second key counted by the counting step is equal to or less than a threshold value related to setting cancellation,
The setting step includes
The key determined to be not more than the threshold value related to the cancellation of the setting by the determining step among the first key and the second key is set as a key that is not subjected to the encryption and decryption. Item 3. A key setting method according to item 1 or 2.
The setting step includes
The key setting method according to claim 7, wherein the key determined by the determining step to be equal to or less than a threshold value related to the setting cancellation is deleted.
The setting step includes
Of the first key and the second key, one key determined by the determining step to be equal to or less than the threshold value related to the setting cancellation is the other key determined to be larger than the threshold value related to the setting cancellation. 8. The key setting method according to claim 7, wherein the key is set to a key that only performs decryption only when the key cannot be decrypted.
The setting step includes
Success in setting the second key of the first key and the second key when both the first key and the second key are determined to be equal to or less than the threshold value related to the cancellation of the setting 3. The key setting method according to claim 1, wherein a key having a smaller number is set as a key that does not perform the encryption and decryption.
The setting step includes
The key setting method according to claim 10, wherein a key having a smaller number of successes after the setting of the second key is deleted from the first key and the second key.
The setting step includes
Decrypting one of the first key and the second key that has a smaller number of successes after setting the second key with the other key determined to be larger than the threshold value related to the cancellation of the setting 11. The key setting method according to claim 10, wherein the key is set to a key for performing only decryption only when it cannot be performed.
The counting step includes
The number of successes after setting the second key that was able to decrypt the encrypted packet received after the second key was set by the setting step is determined for each of the first key and the second key. Counting about
The setting step includes
2. The key having a smaller number of successes after setting the second key out of the first key and the second key is set as a key that is not encrypted and decrypted. Or the key setting method of 2.
The setting step includes
14. The key setting method according to claim 13, wherein a key having a smaller number of successes after setting the second key is deleted from the first key and the second key.
The setting step includes
Of the first key and the second key, one key having a small number of successes after the setting of the second key is set as a key that only performs decryption when the other key cannot be decrypted. The key setting method according to claim 13.
In any one of the plurality of ad hoc networks, encryption and decryption is performed using a gateway-specific first key in one of the ad hoc networks and a second key specific to another gateway in the other ad hoc network. Node
For each received encrypted packet, a counting step of counting the number of successes that can be decrypted with the first key and counting the number of successes that can be decrypted with the second key;
A determination step of determining whether or not each success number counted by the counting step is equal to or less than a threshold value related to setting cancellation;
A setting step of setting a key that is determined to be equal to or less than a threshold value related to the cancellation of the setting by the determination step among the first key and the second key as a key that is not to be encrypted and decrypted;
The key setting method characterized by performing.
The setting step includes
The key setting method according to claim 16, wherein the key determined to be equal to or less than a threshold value related to the cancellation of the setting by the determining step is deleted.
The setting step includes
Of the first key and the second key, one key determined by the determining step to be equal to or less than the threshold value related to the setting cancellation is the other key determined to be larger than the threshold value related to the setting cancellation. The key setting method according to claim 16, wherein the key is set to a key that only performs decryption only when the key cannot be decrypted.
The setting step includes
Success in setting the second key of the first key and the second key when both the first key and the second key are determined to be equal to or less than the threshold value related to the cancellation of the setting The key setting method according to claim 16, wherein a key having a smaller number is set as a key that does not perform the encryption and decryption.
The setting step includes
20. The key setting method according to claim 19, wherein a key having a smaller number of successes after setting the second key is deleted from the first key and the second key.
The setting step includes
Of the first key and the second key, one key having a small number of successes after the setting of the second key is set as a key that only performs decryption when the other key cannot be decrypted. The key setting method according to claim 19.
In any one of the plurality of ad hoc networks, encryption and decryption is performed using a gateway-specific first key in one of the ad hoc networks and a second key specific to another gateway in the other ad hoc network. Node
For each received encrypted packet, a counting step of counting the number of successes that can be decrypted with the first key and counting the number of successes that can be decrypted with the second key;
A setting step of setting the key having the smaller number of successes among the first key and the second key as a key that does not perform the encryption and decryption;
The key setting method characterized by performing.
The setting step includes
23. The key setting method according to claim 22, wherein the key having the smaller number of successes out of the first key and the second key is deleted.
The setting step includes
Only when the one of the first key and the second key having the smaller number of successes cannot be decrypted by the other key determined to be larger than the threshold value related to the cancellation of the setting. 23. The key setting method according to claim 22, wherein the key is set to a key for performing encryption and decryption.
A node in any one of the plurality of ad hoc networks that performs encryption and decryption with a gateway-specific first key in the ad hoc network;
Detection means for detecting the destination or source gateway of the received encrypted packet for each encrypted packet;
Counting means for counting the number of failures that could not decrypt the encrypted packet with the first key for each gateway detected by the detecting means;
Determining means for determining, for each gateway, whether or not the number of failures counted by the counting means is greater than or equal to a threshold value related to key acquisition;
The acquisition request for the second key specific to the gateway determined by the determination means to be equal to or greater than the threshold value is sent to the server storing the key specific to each gateway of the plurality of ad hoc networks via any one of the ad hoc networks. A transmission means for transmitting;
Receiving means for receiving the second key stored in the server as a result of the acquisition request being transmitted by the transmitting means from the server via any one of the ad hoc networks;
Setting means for setting the second key received by the receiving means as a key for encryption and decryption;
A node characterized by comprising:
A node in any one of the plurality of ad hoc networks that performs encryption and decryption with a gateway-specific first key in the ad hoc network;
Detection means for detecting the destination or source gateway of the received encrypted packet for each encrypted packet;
The number of successes in which the encrypted packet could be decrypted with the first key is counted for each gateway detected by the detection means, and the number of failures in which the encrypted packet could not be decrypted with the first key Counting means for counting each gateway;
Determining means for determining for each gateway whether or not a difference obtained by subtracting the number of successes from the number of failures counted by the counting means is greater than or equal to a threshold for key acquisition;
The acquisition request for the second key specific to the gateway determined by the determination means to be equal to or greater than the threshold value is sent to the server storing the key specific to each gateway of the plurality of ad hoc networks via any one of the ad hoc networks. A transmission means for transmitting;
Receiving means for receiving the second key stored in the server as a result of the acquisition request being transmitted by the transmitting means from the server via any one of the ad hoc networks;
Setting means for setting the second key received by the receiving means as a key for encryption and decryption;
A node characterized by comprising:
As a result of the acquisition request being transmitted by the transmission means, the decryption means for decrypting the encrypted packet obtained by encrypting the second key in the server with the first key with the first key;
The setting means includes
27. The node according to claim 25 or 26, wherein the second key decrypted by the decrypting means is set as a key for performing the encryption and decryption.
The setting means includes
27. The node according to claim 25 or 26, wherein when the second key is set as a key that performs encryption and decryption, the first key is set as a key that does not perform encryption and decryption.
The setting means includes
27. The node according to claim 25 or 26, wherein when the second key is set as a key for performing encryption and decryption, the first key is deleted.
The setting means includes
When the second key is set as a key for encryption and decryption, the first key is set as a key for encryption and decryption only when the second key cannot be decrypted. 27. A node according to claim 25 or 26, characterized in that:
The counting means includes
The number of successes after the setting of the second key that was able to decrypt the encrypted packet received after the setting of the second key by the setting means is set as the first key and the second key, respectively. Counting about
The determination means includes
It is determined for each of the first key and the second key whether the number of successes after setting of the second key counted by the counting means is equal to or less than a threshold value related to setting cancellation,
The setting means includes
The key that is determined by the determining means to be equal to or less than the threshold value related to the cancellation of the setting among the first key and the second key is set as a key that is not subjected to the encryption and decryption. Item 27. The node according to item 25 or 26.
The setting means includes
32. The node according to claim 31, wherein a key determined by the determining means to be equal to or less than a threshold value related to the cancellation of the setting is deleted.
The setting means includes
Of the first key and the second key, one key determined by the determining means to be equal to or lower than the threshold value related to the cancellation of setting is the other key determined to be larger than the threshold value related to the setting cancellation. 32. The node according to claim 31, wherein the node is set to a key that only performs decryption when the key cannot be decrypted.
The setting means includes
Success in setting the second key of the first key and the second key when both the first key and the second key are determined to be equal to or less than the threshold value related to the cancellation of the setting 27. The node according to claim 25 or 26, wherein a key having a smaller number is set to a key that does not perform the encryption and decryption.
The setting means includes
35. The node according to claim 34, wherein a key having a smaller number of successes after setting the second key is deleted from the first key and the second key.
The setting means includes
Decrypting one of the first key and the second key that has a smaller number of successes after setting the second key with the other key determined to be larger than the threshold value related to the cancellation of the setting 35. The node according to claim 34, wherein the node is set to a key for performing only decryption only when it cannot be performed.
The counting means includes
The number of successes after the setting of the second key that was able to decrypt the encrypted packet received after the setting of the second key by the setting means is set as the first key and the second key, respectively. Counting about
The setting means includes
26. The key having the smaller number of successes after setting the second key out of the first key and the second key is set as a key that is not encrypted and decrypted. Or the node according to 26.
The setting means includes
38. The node according to claim 37, wherein a key having a smaller number of successes after setting the second key is deleted from the first key and the second key.
The setting means includes
Of the first key and the second key, one key having a small number of successes after the setting of the second key is set as a key that only performs decryption when the other key cannot be decrypted. 38. The node of claim 37.
In any one of the plurality of ad hoc networks, encryption and decryption is performed using a gateway-specific first key in one of the ad hoc networks and a second key specific to another gateway in the other ad hoc network. A node,
Counting means for counting the number of successes that can be decrypted with the first key for each received encrypted packet, and for counting the number of successes that can be decrypted with the second key;
Determining means for determining whether each success number counted by the counting means is equal to or less than a threshold value related to setting cancellation;
A setting unit that sets a key that is determined to be equal to or less than a threshold value related to the cancellation of setting by the determination unit among the first key and the second key, as a key that does not perform the encryption and decryption;
A node characterized by comprising:
The setting means includes
41. The node according to claim 40, wherein the key determined by the determining means to be equal to or less than a threshold value related to the setting cancellation is deleted.
The setting means includes
Of the first key and the second key, one key determined by the determining means to be equal to or lower than the threshold value related to the cancellation of setting is the other key determined to be larger than the threshold value related to the setting cancellation. 42. The node according to claim 41, wherein the node is set to a key that only performs decryption when the key cannot be decrypted.
The setting means includes
Success in setting the second key of the first key and the second key when both the first key and the second key are determined to be equal to or less than the threshold value related to the cancellation of the setting 42. The node according to claim 41, wherein a key having a smaller number is set as a key that does not perform the encryption and decryption.
The setting means includes
44. The node according to claim 43, wherein a key having a smaller number of successes after setting the second key is deleted from the first key and the second key.
The setting means includes
Of the first key and the second key, one key having a small number of successes after the setting of the second key is set as a key that only performs decryption when the other key cannot be decrypted. 44. The node of claim 43.
In any one of the plurality of ad hoc networks, encryption and decryption is performed using a gateway-specific first key in one of the ad hoc networks and a second key specific to another gateway in the other ad hoc network. A node,
Counting means for counting the number of successes that can be decrypted with the first key for each received encrypted packet, and for counting the number of successes that can be decrypted with the second key;
Setting means for setting a key having the smaller number of successes among the first key and the second key as a key that does not perform the encryption and decryption;
A node characterized by comprising:
The setting means includes
47. The node according to claim 46, wherein a key having the smaller number of successes out of the first key and the second key is deleted.
The setting means includes
Only when the one of the first key and the second key having the smaller number of successes cannot be decrypted by the other key determined to be larger than the threshold value related to the cancellation of the setting. The node according to claim 46, wherein the node is set to a key for performing encryption and decryption.
A server capable of communicating with each gateway of a plurality of ad hoc networks,
Storage means for storing the gateway identification information and the gateway-specific key for each gateway;
A request for acquiring a second key specific to a gateway different from a first key specific to a gateway in any one of the ad hoc networks from a node in any one of the plurality of ad hoc networks. Receiving means for receiving via an ad hoc network,
Extraction means for extracting the second key from the storage means based on identification information of a gateway that uses the second key included in the second key acquisition request received by the reception means When,
Transmitting means for transmitting the second key extracted by the extracting means to the node via any one of the ad hoc networks;
A server comprising:
A server capable of communicating with each gateway of a plurality of ad hoc networks,
Storage means for storing the gateway identification information, location information, and the gateway-specific key for each gateway;
A request for acquiring a second key specific to a gateway different from a first key specific to a gateway in any one of the ad hoc networks from a node in any one of the plurality of ad hoc networks. Receiving means for receiving via an ad hoc network,
Extraction means for extracting the second key from the storage means based on identification information of a gateway that uses the second key included in the second key acquisition request received by the reception means When,
Determining means for determining whether or not to transmit the second key to the node based on position information of the gateway using the first key and position information of the gateway using the second key; ,
A transmission means for transmitting the second key extracted by the extraction means to the node via any one of the ad hoc networks when it is determined by the determination means to be transmitted;
A server comprising:
A server capable of communicating with each gateway of a plurality of ad hoc networks,
Storage means for storing, for each gateway, identification information of the gateway, history information regarding the use frequency of the gateway-specific key and another gateway-specific key,
A request for acquiring a second key specific to a gateway different from a first key specific to a gateway in any one of the ad hoc networks from a node in any one of the plurality of ad hoc networks. Receiving means for receiving via an ad hoc network,
Extraction means for extracting the second key from the storage means based on identification information of a gateway that uses the second key included in the second key acquisition request received by the reception means When,
Determining means for determining whether or not to transmit the second key to the node based on history information of the gateway using the first key and history information of the gateway using the second key; ,
A transmission means for transmitting the second key extracted by the extraction means to the node via any one of the ad hoc networks when it is determined by the determination means to be transmitted;
A server comprising:
It is possible to communicate with a node in any one of the ad hoc networks that performs encryption and decryption with a first key specific to the gateway in any one of the plurality of ad hoc networks, and a gateway of each of the plurality of ad hoc networks. A network system comprising: a server having storage means for storing the gateway identification information and the gateway-specific key for each gateway;
The node is
Detection means for detecting the destination or source gateway of the received encrypted packet for each encrypted packet;
Counting means for counting the number of failures that could not decrypt the encrypted packet with the first key for each gateway detected by the detecting means;
Determining means for determining, for each gateway, whether or not the number of failures counted by the counting means is greater than or equal to a threshold value related to key acquisition;
First transmission means for transmitting the gateway-specific second key acquisition request determined by the determination means to be equal to or greater than the threshold value to the server via any one of the ad hoc networks;
As a result of the acquisition request being transmitted by the first transmission means, the second key stored in the storage means of the server is received from the server via any one of the ad hoc networks. Receiving means;
Setting means for setting the second key received by the receiving means as a key for performing encryption and decryption,
The server
Second receiving means for receiving the second key acquisition request transmitted by the first transmitting means via any one of the ad hoc networks;
Extracting the second key from the storage unit based on identification information of the gateway using the second key included in the second key acquisition request received by the second receiving unit Extraction means to
Second transmission means for transmitting the second key extracted by the extraction means to the node via any one of the ad hoc networks;
A network system comprising:
It is possible to communicate with a node in any one of the ad hoc networks that performs encryption and decryption with a first key specific to the gateway in any one of the plurality of ad hoc networks, and a gateway of each of the plurality of ad hoc networks. A network system comprising: a server having storage means for storing the gateway identification information and the gateway-specific key for each gateway;
The node is
Detection means for detecting the destination or source gateway of the received encrypted packet for each encrypted packet;
The number of successes in which the encrypted packet could be decrypted with the first key is counted for each gateway detected by the detection means, and the number of failures in which the encrypted packet could not be decrypted with the first key Counting means for counting each gateway;
Determining means for determining for each gateway whether or not a difference obtained by subtracting the number of successes from the number of failures counted by the counting means is greater than or equal to a threshold for key acquisition;
First transmission means for transmitting the gateway-specific second key acquisition request determined by the determination means to be equal to or greater than the threshold value to the server via any one of the ad hoc networks;
First receiving means for receiving the second key stored in the server as a result of the acquisition request being transmitted by the first transmitting means from the server via any one of the ad hoc networks;
Setting means for setting the second key received by the first receiving means as a key for performing encryption and decryption,
The server
Second receiving means for receiving the second key acquisition request transmitted by the first transmitting means via any one of the ad hoc networks;
Extracting the second key from the storage unit based on identification information of the gateway using the second key included in the second key acquisition request received by the second receiving unit Extraction means to
Second transmission means for transmitting the second key extracted by the extraction means to the node via any one of the ad hoc networks;
A network system comprising: