KR20080046392A - Method of generating encryption key used in communication in accordance with data density in wireless sensor network, and method for data communication using above mentioned method, and system for these purpose - Google Patents

Abstract

A method for generating an encryption key for communication in a wireless sensor network, a data communication method using the same, and a system using the same are provided to maximize the energy efficiency of a sensor node and to improve security by applying different encryption keys to data density of data communication. A normal node(600) encrypts data sensed by using an encryption key generated by a symmetrical ciphering algorithm and transfers the encrypted data to a representative node(202). The representative node decrypts the encrypted data. The representative node encrypts the decrypted data by using an encryption key generated by using an asymmetrical ciphering algorithm, and transfers the encrypted data to a manager node(120). The manager node decrypts the encrypted data and transfers the decrypted data to a sensing information management server(130). The sensing information management server determines whether an abnormal effect is generated from a particular region on the basis of the received data. The sensing information management server transfers the results to a user terminal(142).

Description

{Method of generating encryption key used in communication in according with data density in wireless sensor network, and method for data communication using above mentioned Method, and System for these purpose}

1 is a conceptual diagram of a wireless sensor network system according to a preferred embodiment of the present invention;

2A to 2C are conceptual views illustrating a structure and a communication method of a wireless sensor network system according to a preferred embodiment of the present invention;

3 is a block diagram illustrating an internal configuration of a sensor node provided in a wireless sensor network system according to a preferred embodiment of the present invention;

4 is a time slot diagram of a LEACH protocol for explaining election and operation of a representative node in a wireless sensor network system according to a preferred embodiment of the present invention;

FIG. 5A is a flowchart illustrating a method of performing data communication using a symmetric key encryption method in a wireless sensor network system having a conventional hierarchical structure.

5B is a flowchart illustrating a method of performing data communication using a public key encryption method in a wireless sensor network system having a conventional hierarchical structure.

6A is a flowchart illustrating symmetric key generation for data encryption between a normal node and a representative node in a wireless sensor network system according to a preferred embodiment of the present invention;

6B is a flowchart illustrating the generation of a public key for data encryption between a representative node and a manager node in a wireless sensor network system according to a preferred embodiment of the present invention.

7 is a flowchart illustrating a method of operating a wireless sensor network system according to a preferred embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

100: wireless sensor network system 110: sensor node

112: sensor field 120: manager node

130: sensing information management server 132: sensing information management database

140: administrator terminal 142: user terminal

150: wired and wireless communication network 200: cluster

202: representative node 204: general node

300: sensing unit 310: processing unit

320: transceiver 330: power unit

The present invention relates to a method for generating an encryption key for communication according to data density in a wireless sensor network, a data communication method using the same, and a system therefor. More specifically, data communication between a sensor node disposed in a sensor field in a wireless sensor network having a hierarchical structure and a representative node controlling sensor nodes belonging to a specific group including the sensor node (I.e., in-group data communication with low data density), a manager node which performs encryption / decryption using a symmetric key and manages information obtained from all the sensor nodes arranged in the representative node and other representative nodes or sensor fields. The data communication between groups (that is, data communication between groups with high data density or data communication with a group manager) performs encryption / decryption using a public key, thereby simultaneously ensuring node energy efficiency and improving security of transmitted data. Generates encryption key for communication based on data density in wireless sensor network Relates to a data communication method and system for using these methods, it.

Recently, wireless sensor networks are emerging as a new research field due to the development of wireless communication technology, low power circuit design, and miniaturization of computing devices. In particular, with the advent of the ubiquitous era in which users can easily connect to a network anytime and anywhere without being aware of a terminal such as a computer, such a wireless sensor network combines an existing computing environment with a physical physical environment. It is getting more attention by playing a role.

In general, a wireless sensor network places sensor nodes granted computing power and wireless communication capability in a specific place such as a natural environment or a battlefield to form an autonomous network in a sensor field. It provides a communication network to share sensing information with a sink node or a base station. Accordingly, wireless sensor networks are currently being applied to various fields from military, firefighting, transportation, medical, environmental monitoring, building control, home networks and other industries to everyday life.

However, in order for such a wireless sensor network to operate smoothly, the following requirements must be satisfied. First, the sensor node manufactured with the miniaturized device should be satisfied to operate for a long time by making full use of the power supplied from the battery mounted therein. In other words, sensor nodes placed in the sensor field forming the network need to be designed to consume low power in operation so that maximum efficiency is obtained using limited resources (energy efficiency).

Second, for the accuracy of sensing by the sensor node and the expansion of the sensing area, a large number of sensor nodes in a certain area (usually thousands to tens of thousands) must be closely arranged.

Third, self-organizing ability to adapt to dynamic situation change and cooperative information transfer system between sensor nodes should be satisfied. For this purpose, an Ad-Hoc Network, which has a large scale of scalability and a multi-hop autonomous configuration capability of maximizing energy efficiency, is being applied to a wireless sensor network.

Fourth, when transmitting sensing information acquired by a large number of sensor nodes to a collecting node through a wireless network, it should be satisfied that systematic communication is performed between the nodes. This is to prevent wasted time and energy due to the low efficiency of the wireless channel and the retransmission of information due to transmission collisions, which are caused when each independent sensor node attempts to deliver sensing information by competitively accessing the wireless channel. to be.

Fifth, security must be ensured to give confidentiality and integrity to data communication between nodes. Thus, in the related art, a specific encryption key such as a symmetric key or a public key is used to encrypt / decrypt data transmitted. When a symmetric key is used as an encryption key, the same key is determined between nodes before data communication is performed. Then, when the node encrypts / decrypts data, the time required for key generation can be reduced to improve the speed of encryption / decryption. In other words, the node can be operated by consuming low power. In this case, however, secure key exchange (or key distribution) must be made between the nodes. Otherwise (that is, if a particular node loses or exposes the key), you run the risk of data being exposed to the outside. In addition, when a large number of nodes perform data communication with a specific node, a problem arises in that the number of keys that the specific node must manage increases.

On the other hand, when a public key is used as an encryption key, when a specific node performs encryption using a public key according to a key agreement among two nodes performing data communication, the other node uses the private key associated with the public key ( Decryption using a private key). This is advantageous in that the security of data can be maintained more securely since no key exchange is required between the nodes that perform data communication. However, in this case, the length of the key is longer than the symmetric key is used, and the algorithm used for encryption / decryption is complicated, so that a node spends a lot of time and power to perform encryption / decryption.

Meanwhile, according to the paper "Energy-Efficient Communication Protocol for Wireless Microsensor Networks" published by Wendi Rabiner Heinzelman, Anantha Chandrakasan and Hari Balakrishnan at the 2000 Proceedings of the 33rd Hawaii International Conference on System Sciences, There are two types of communication in the network. One of them is the communication between the sensor node and the representative node which is performed inside the group, and the other is the communication between the representative node and the manager node which is performed outside the group. However, the paper assumes no external attack while these communications are deployed. However, in a real environment, since the possibility of attack is sufficient, when a communication is performed in a state where the channel is not secure, data may be damaged or exposed to the outside.

In order to solve the above problems, the present invention provides a data structure in a wireless sensor network, wherein a hierarchical topology is applied to a wireless sensor network so that systematic communication between nodes arranged in a sensor field can be achieved. An object of the present invention is to provide a method for generating a communication encryption key according to the degree of integration, a data communication method using the same, and a system therefor.

In addition, in the above-described case, the symmetric key is used for encryption / decryption for data communication between nodes having low data density (that is, data communication between sensor nodes and representative nodes), and data between nodes with high data density. In communication (i.e., data communication between a specific representative node and another representative node or manager node), the public key is used for encryption / decryption to enable low power consumption of the sensor node and to improve security for data protection. It is an object of the present invention to provide a method for generating an encryption key for communication according to data density in a wireless sensor network, a data communication method using the same, and a system therefor.

In order to achieve the above object, the present invention provides a method for generating an encryption key in a wireless sensor network having a hierarchical structure, wherein the encryption key is generated using a symmetric encryption algorithm in communication occurring between nodes with low data density. In the communication occurring between the nodes having high data density, the encryption key is generated by using an asymmetric encryption algorithm. The wireless sensor network having a hierarchical structure provides a method for generating a communication encryption key according to the data density. do.

Specifically, the communication between the nodes having low data density is communication between a general node detecting peripheral information in the wireless sensor network and a representative node managing a cluster to which the general node belongs, and between the high data integration nodes. The communication is characterized in that communication between the representative node and the manager node for managing all clusters provided in the wireless sensor network.

More specifically, the encryption key generated during the communication between the nodes with low data density is generated based on a random number generated by the general node, a random number generated by the representative node, and a random number generated by the manager node. do.

More specifically, it is preferable that the general node delivers a random number generated by the general node when it transmits the intention to join the cluster to the representative node. In addition, it is preferable that the representative node delivers a random number generated by the representative node when transmitting the schedule that records the communication time between the nodes to the general node. In addition, the manager node, when notifying that the representative node has been selected as the representative, it is preferable to deliver a public key generated by itself. In addition, the representative node is preferably replaced after communicating with all the general nodes provided in the cluster.

In addition, the present invention is a method for communicating using an encryption key in a wireless sensor network having a hierarchical structure, comprising: (a) encrypting data sensed using an encryption key generated by a general node using a symmetric encryption algorithm; Forwarding to a representative node after; (b) decrypting the encrypted data by the representative node; (c) encrypting the decrypted data by using the encryption key generated by the representative node using an asymmetric encryption algorithm and transmitting the encrypted data to the manager node; (d) decrypting the encrypted data by the manager node and collecting the encrypted data and transmitting the collected data to a sensing information management server; (e) determining whether or not an abnormality has occurred in a specific region based on the data transmitted by the sensing information management server; And (f) informing the user terminal of the fact that the sensing information management server has determined the data, using a communication encryption key generated according to the data density in the wireless sensor network having a hierarchical structure. .

Specifically, the step (d), (a1) preferably further comprises the step of determining whether or not the abnormal phenomenon has occurred in a specific region based on the data collected by the manager node.

More specifically, the general node, when direct communication with the representative node is impossible, the communication is deployed through the general node located in the most recent distance of the representative node, the representative node is not possible to communicate directly with the manager node Preferably, the communication is deployed through the representative node located at the most recent distance of the manager node.

The present invention also provides a system in which a wireless sensor network having a hierarchical structure is implemented, the general node detecting peripheral information; A representative node managing a cluster to which the general node belongs; And a manager node managing all clusters provided in the wireless sensor network, wherein the general node or the representative node includes a random number generated by the general node, a random number generated by the representative node, and a manager node. Provided is a wireless sensor network system having a hierarchical structure characterized by generating an encryption key using a symmetric encryption algorithm based on a random number.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. First of all, in adding reference numerals to the components of each drawing, it should be noted that the same reference numerals have the same reference numerals as much as possible even if displayed on different drawings. In addition, in describing the present invention, when it is determined that the detailed description of the related well-known configuration or function may obscure the gist of the present invention, the detailed description thereof will be omitted. In addition, the following will describe a preferred embodiment of the present invention, but the technical idea of the present invention is not limited thereto and may be variously modified and modified by those skilled in the art.

The present invention generates an encryption key for communication according to the data density on a system in which a wireless sensor network having a hierarchical structure is operated, so that a sensor node that cannot be supplied with power can be smoothly operated even at low power, and at the same time, data communication between nodes. It is characterized by improving the security of the city. Here, generating the encryption key for communication according to the data density means that data communication between the sensor nodes distributed in the sensor field and the representative nodes controlling the sensor nodes belonging to the group (that is, communication between nodes with low data density) Uses symmetric encryption algorithm to generate encryption key, and asymmetric encryption algorithm is used for communication between specific representative node and other representative node or manager node managing whole sensor node (that is, communication between nodes with high data density). To generate an encryption key. The present invention can be applied to a communication network (that is, a wireless sensor network having a hierarchical structure) for maximizing energy efficiency and / or differentiated security strength in environments where data integration is various. Hereinafter, a more detailed description thereof will be developed.

1 is a conceptual diagram of a wireless sensor network system according to a preferred embodiment of the present invention. As shown in FIG. 1, the wireless sensor network system 100 according to a preferred embodiment of the present invention includes a sensor node 110, a manager node 120, a sensing information management server 130, and a sensing information management database ( 132, an administrator terminal 140, and a user terminal 142.

In the wireless sensor network system 100 according to the present invention, when the sensor node 110 distributed in a certain region (sensor field) 112 senses and acquires specific information (hereinafter, referred to as sensing information), the manager node 120 determines a predetermined path. This is collected through the sensing information management server 130 to be delivered. Then, the sensing information management server 130 determines whether there is an abnormality using this, and stores all or classified data related to the sensing information database 132. Then, the user (or the observer) can access the sensing information management server 130 through the user terminal 142 and check it. Here, when the sensor node 110 is disposed in the forest area, the sensing information may be information for detecting whether a fire has occurred. Meanwhile, the manager node 120 may directly transmit sensing information to the user terminal 142 through a wired or wireless communication network. In this case, it is preferable that the manager node 120 or the user terminal 142 is designed to process the sensing information so that the user can easily recognize the sensing information.

The wireless sensor network system 100 according to the present invention is characterized by having a hierarchical structure. As described in the technical field to which the present invention pertains and the prior art in the field, a multi-hop ad hoc network is generally applied to the wireless sensor network in order to maximize the scalability and energy efficiency of the sensor node. However, such a multi-hop ad hoc network is classified into a flat topology network and a hierarchical network according to its structure. In a planar network, all nodes act as routers, so each node must perform direct / indirect communication to the destination via other nodes dynamically selected by the routing algorithm. For this purpose, a table-driven routing algorithm or an on-demand routing algorithm, which is a technique in which each node discovers a path on its own, is mainly used. Since they do not exist, the nodes themselves control data transmission through a distributed method such as carrier sensing multiple access / collision avoidance (CSMA / CA).

On the other hand, in the hierarchical network, a representative node that manages a plurality of nodes is elected, and the elected node plays a role of allocating and controlling ID and radio resources of the node that it manages. Here, the group formed by the aggregation of representative nodes and general nodes controlled by resource allocation is called a cluster, and a series of processes of selecting representative nodes from all nodes in the network and constituting the cluster are performed. Clustering). In a hierarchical network, such clustering must be preceded before its construction.

However, data aggregation must be performed in the process of transferring the information collected from the sensor node to the sink node, and in this process, the energy efficiency of each node consumed for data transfer must be maximized. In consideration of this aspect, it is preferable that a multi-hop ad hoc network of a hierarchical network type is applied to the wireless sensor network system 100 according to the present invention. On the other hand, the biggest limitation of a multi-hop ad hoc network in the form of a hierarchical network is a problem of mutual interference between representative nodes. In order to solve this problem, a plurality of frequency channels or code channels are used in the wireless sensor network system 100 according to the present invention. That is, the same channel is used for communication occurring inside the cluster, and another channel is used for communication occurring between representative nodes. However, in the practice of the present invention, the wireless sensor network system 100 may configure a hierarchical network having only a single channel. In this case, in order to maximize network scalability, resource efficiency, and energy efficiency, for example, Kim Il-hwan, Kim Yong-seok and Kang Choong-gu presented in the 2005 First Telecommunication Standardization Proceedings, "The Dual-Layer Evolutionary Media Access for Wireless Sensor Networks. It is also possible to apply the HiPERMAC (Hierarchically Paired Evolutionary Radio MAC) protocol proposed in "Control and Network Protocol: Cross Layer Design Approach".

The wireless sensor network system 100 according to the present invention is characterized in that it is operated using a clustering-based hierarchical routing protocol. In particular, the wireless sensor network system 100 is characterized in that it operates using the Low-Energy Adaptive Clustering Hierarchy (LEACH) protocol. In general, in the wireless sensor network system 100 having a hierarchical structure, data reduction is required to prevent energy waste due to redundant transmission of similar information between adjacent nodes. That is, when similar information about an event occurring in an adjacent area is delivered to the representative node, the representative node performs data reduction to enable more energy efficient routing. In addition, delivery by the representative node to the requested query can prevent flooding of the inefficient query. Wireless sensor network system 100 according to the present invention, for example, Wendi Rabiner Heinzelman, Anantha Chandrakasan and Hari Balakrishnan published in 2000 "Proceedings of the 33rd Hawaii International Conference on System Sciences, 1-10" "Energy-Effcient Communication It is also possible to use the LEACH protocol proposed in "Protocol for Wireless Microsensor Networks."

The wireless sensor network system 100 according to the present invention is characterized by generating a communication encryption key using a specific encryption algorithm according to the degree of data integration. That is, in low-density communication (data communication from the sensor node 110 to the representative node 202), data encryption is developed using a symmetric key, and high-density communication (representative node 202 is different from the other). In the representative node 202 or the manager node 120, data encryption is performed using the public key. Hereinafter, this will be described in more detail.

In general, the symmetric key encryption method using the symmetric key to encrypt the data has a simple algorithm (SEED, DES, DES3, AES, etc.) to minimize the energy consumption to encrypt the data instead of providing a low security strength There is a characteristic. On the other hand, the public key encryption method using the public key to encrypt data has a feature that provides a high security strength, although it consumes a lot of energy to encrypt the data due to the complicated algorithm. In view of the above, the present invention reduces the power consumption of the sensor node 110 by using a symmetric key encryption method and a public key encryption method according to the situation, and reduces the power consumption of the sensor node 110. It is possible to improve the strength. A method of using a symmetric key encryption method and a public key encryption method in combination will be described below with reference to FIG. 5.

On the other hand, the public key encryption method encrypts the key value using an asymmetric cryptographic algorithm (RSA, ECC, etc.) to solve key bootstraping (or key agreement problem), which is a problem that the symmetric key encryption method exposes, and then transmits the actual key value. Provides an algorithm (e.g., Diffie-Hellman) that can generate the same key value between each other without transmission. In the present invention, it is also possible to apply an elliptic curve encryption algorithm to the public key encryption method in order to reduce the size of the encryption key used in the public key encryption method. In the present invention, Seo Seok-chung, Kim Hyung-chan and R.S. A method proposed by Ramakrishna in the November 24, 2005, Proceedings of the 24th Fall Conference of the Korea Information Processing Society, "Security Protocol based on Shared Key Setting Using Elliptic Curve Cryptography in Wireless Sensor Networks." It is also possible to be used.

On the other hand, in the clustering-based hierarchical routing protocol, the wireless sensor network system 100 is configured as follows. Hereinafter, a detailed description will be given with reference to FIG. 2. 2A to 2C are conceptual views illustrating a structure and a communication method of a wireless sensor network system according to a preferred embodiment of the present invention.

Referring to FIG. 2A, the wireless sensor network system 100 is divided into small regions called clusters 200, and each cluster 200 has a representative node (representative node 202 described above). The sensor node 110 except for the representative node 202 becomes the general node 204. The representative node 202 functions to collect data from general nodes to which it belongs as shown in FIG. 2B. The representative node 202 then functions to deliver the collected and processed data to the manager node 120 or another representative node 202 as shown in FIG. 2C.

In the wireless sensor network system 100 having a hierarchical structure, in particular, the wireless sensor network system 100 operated by the LEACH protocol, the representative node 202, the general node 204, and the autonomous intention of the sensor node 110 are used. Cluster 200 is determined. A more detailed description thereof will be described below with reference to FIG. 4. However, in the embodiment of the present invention, the wireless sensor network system 100 may determine the representative node 202, the general node 204, and the cluster 200 according to the following. That is, the cluster 200 is set by the manager node 120 after first placing sensor nodes for smooth transmission of information through the formed layer. Then, the manager node 120 may select a specific sensor node 110 among the sensor nodes belonging to the configured cluster 200 and assume a role of the representative node 202 of the cluster 200.

Meanwhile, in the present invention, the communication method according to the data density is classified into intra-group data communication as shown in FIG. 2B and inter-group data communication as shown in FIG. 2C or data communication with the manager node 120. Herein, in-group data communication refers to communication between the general node 204 and the representative node 202 as described above, and inter-group data communication refers to communication between the representative nodes 202. The data communication with the manager node 120 refers to the communication between the representative node 202 and the manager node 120. However, in the wireless sensor network system 100, it is common that the representative node 202 directly communicates with the manager node 120 as in ① of FIG. 2C. However, this may not happen in the wireless sensor network system 100. In this case, as shown in ② of FIG. 2C, the representative node 202 transmits data to the manager node 120 to another representative node 202 that is at the most recent distance. Then, the representative node 202 receiving the data performs the function of data transfer instead to the manager node 120.

Hereinafter, the wireless sensor network system 100 will be described with reference to FIG. 1 again.

In the wireless sensor network system 100 according to the present invention, scalability and adaptability are preferably reflected in a network so as to quickly and effectively respond to changes in network size or changes in topology.

In addition, the wireless sensor network system 100 according to the present invention may be based on a proactive routing protocol, a reactive routing protocol, or a hybrid scheme, depending on how the data movement path is set. It is also possible to use a routing protocol or the like. Here, the dictionary method refers to the manner in which all data movement paths are established at the same time the network is formed. The reactive method refers to a method in which a specific path is established in the network only when a data movement path is required. In addition, the hybrid method refers to a method in which the two methods are appropriately mixed and set. On the other hand, the wireless sensor network system 100 according to the present invention may be applied to the mesh (Mesh) network.

The sensor node 110 is a sensing device provided with computing power, and refers to an intelligent communication device constituting a wireless sensor network. When the sensor node 110 becomes a general node (that is, reference numeral 204 of FIG. 2) in the embodiment of the present invention, the physical node data is collected and the real-time situation detection information is represented using wireless communication in response to the change of the situation. It functions to deliver to the node (ie, reference numeral 202 of FIG. 2). Herein, the wireless communication refers to a general RF communication, and Zigbee, Bluetooth, Wi-Fi, etc. may be applied thereto. Meanwhile, when the plurality of sensor nodes 110 arranged in the sensor field form a group for a predetermined time, the representative node is representative of the sensor nodes belonging to the group and is responsible for the control function of the entire general node. Say). A more detailed description of these representative nodes will be described later.

The sensor node 110 may include a sensor, a local storage module, a communication module, a processor, and a battery therein. For example, such a sensor node 110 is shown by Jamal N. Al-Karaki and Ahmed E. Kamal in "Routing Techniques in Wireless Sensor Networks: A Survey," published in IEEE Wireless Communications 11, 6-28, 2004. It can be configured together. A detailed description of the internal configuration of the sensor node 110 will be described below with reference to FIG. 3.

The sensor node 110 in the wireless sensor network system 100 operates independently of other sensor nodes or manager nodes 120. Therefore, the sensor node 110 is provided therein, and it is inevitable that the driving of the battery is limited to a limited amount of energy. However, the sensor node 110 usually consumes energy while performing functions such as sensing, processing, and communicating. In particular, the sensor node 110 consumes a lot of energy when performing a communication function. Thus, frequent communication of sensor nodes 110 significantly shortens their lifespan, resulting in the problem of having to relocate new sensor nodes 110. Therefore, the sensor node 110 according to the present invention is preferably provided to solve this problem. For example, if the sensor node 110 according to the present invention fails to transmit information to the representative node when the normal node, the sensor node 110 may also transmit information to the representative node through the general node at the shortest distance of the representative node. In addition, the general node according to the present invention may be provided with a time for delivering information from the representative node and deliver the information at the corresponding time.

On the other hand, the sensor node 110 is also preferable to solve the collision, Overhearing, Control Packet Overhead, Idle Listening, etc. that causes the waste of energy. Here, Collision refers to a case where the packet information cannot be used due to corruption of packet information during packet collision. In this case, the sensor node 110 has a burden of retransmitting a packet containing information. On the other hand, overhearing refers to a case in which the sensor node 110 receives this even though the destination is a node other than itself. In this case, the sensor node 110 has a burden of transmitting the received packet to the node corresponding to the destination. On the other hand, the Control Packet Overhead refers to a case in which a packet that is not required to be transmitted like a network control packet is transmitted in addition to the sensing information acquired by the sensor node 110. On the other hand, Idle Listening refers to a case in which the sensor node 110 continuously maintains the standby state without entering a sleep state because the sensor node 110 does not know when to receive data from another node.

The sensor node 110 is typically implemented with Crossbow's Mica series, Intel's iMote, Mote's Telos, Octacom's Nano-24, Macpole's TIP series, Hanbaek Electronics' ZigbeX Mote, Huins UStar-2000, etc. Can be. At this time, the sensor node 110 may use a Tiny OS developed by UC Berkeley, Nano-Q-Plus developed by ETRI (Korea Institute of Electronics and Telecommunications) as its operating system in consideration of size and energy efficiency. In addition, in the present invention, the sensor node 110 may be implemented by Certicom Security (http://www.govtech.net/magazine/channel_story.php/99039) made by Certicom, Canada. Certicom Security provides the ability to secure data using elliptic curve passwords.

The sensor node 110 may also include a location finding system such as a GPS module so that the sensing information management server 130 can easily recognize the location thereof.

The representative node is a cluster head, which is a sensor node that is a main agent of a path setting that gives an ID to each node in a cluster (ie, reference numeral 200 of FIG. 2). The representative node collects the information acquired by the general nodes to which it belongs and stores or processes it, or delivers it to another representative node or manager node 120 to perform an energy-intensive function. In addition, the representative node manages a TDMA-based frame and performs a central function of central scheduling, which reserves and allocates TDMA slots from each node. These representative nodes are continuously energized from the outside.

The representative node may perform a function of combining the sensing information acquired by the general node to which the representative node belongs in the embodiment of the present invention, and may maximize energy efficiency through scheduling based on scheduling and control of the sleep period. That is, in the present invention, it is also possible to centralize the main control and processing functions to the representative node to more efficiently perform routing and media access control (MAC) in the wireless sensor network system 100.

Meanwhile, in the embodiment of the present invention, a method of selecting the representative node and a method of operating the cluster for a predetermined time will be described below with reference to FIG. 4.

The manager node 120 is a conventional think node, and performs the gateway function in the present invention. That is, the manager node 120 is connected to the representative nodes through RF communication, and the wired / wireless communication network 150 such as the internet network is connected to the sensing information management server 130. The manager node 120 receives the information acquired by the general nodes distributed in the predetermined region 112 from the representative node and delivers the information to the sensing information management server 130. Here, the wired / wireless communication network 150 is generally an internet network, but is not limited thereto. For example, the wired / wireless communication network 150 may be formed of a mobile communication network such as a CDMA network or a wireless personal area network (WPAN) network.

On the other hand, such a manager node 120 may be designed to enable a wireless LAN using an interface card slot (eg, PCMCIA slot) to easily cope with changes in the wireless communication network to be expanded later.

The sensing information management server 130 is a server that collects and processes the sensing information acquired by the sensor node 110. The sensing information management server 130 determines whether an abnormality occurs from the sensing information, and processes the information to provide it to the user terminal 142.

The sensing information management server 130 is a distributed process for operating one or more applications in a mutually cooperative environment so as to obtain a desired result desired by the client through a cooperative operation between the client requesting the service and the server processing the client's request. It processes and provides requests of the manager node 120, the manager terminal 140, and the user terminal 142 through a wired / wireless communication network in a client / server manner. The sensing information management server 130 may include a series of application programs for providing various services according to the present invention, in addition to a server program that is commonly used.

The sensing information management database 132 records or stores information performed by the sensing information management server 130 or provides a database containing stored information. The sensing information management database 132 according to the preferred embodiment of the present invention stores the sensing data and the sensor data. However, in the practice of the present invention, the information stored in the sensing information management database 132 is not limited thereto.

The manager terminal 140 is a terminal to which a person managing the sensing information management server 130 connects.

The user terminal 142 is a terminal to which a person who installs the sensor node 110 according to the present invention or a person who requests sensing information is connected to a certain region 112. The user terminal 142 not only receives information from the sensing information management server 130 but also performs a function of requesting the information. In the present invention, when the user terminal 142 accesses the sensing information management server 130 to request sensing information, the sensing information management server 130 authenticates the user terminal 142 (that is, the user terminal 142 is authenticated). It is desirable to determine whether the user connected through a legitimate user). This is to further improve the security of the sensing information.

Next, the internal structure of the sensor node 110 is demonstrated. 3 is a block diagram illustrating an internal configuration of a sensor node provided in a wireless sensor network system according to a preferred embodiment of the present invention.

As shown in FIG. 3, the sensor node 110 according to a preferred embodiment of the present invention includes a sensing unit 300, a processing unit 310, a transceiver 320, and a power unit. (Power Unit; 330).

The sensor node 110, once deployed, is difficult to maintain, and is preferably designed to be low power and robust in structure because it must operate for a few days to many years. In addition, the sensor node 110 is preferably equipped with flexibility and modularity so that it can be effectively used in any structure. In addition, the sensor node 110 may be attached to a variety of sensors, it is preferable to have a structure so that it can be easily replaced with hardware for the purpose. In addition, the sensor node 110 more preferably has a low product price and a small size in consideration of marketability.

The sensing unit 300 is provided with a sensor 302 for detecting various events occurring at the place where the sensor unit 300 is arranged, and an analog / digital converter 304 for converting the sensed analog signal into a digital signal.

The processing unit 310 includes a processor 312 that controls (operates) the overall operation of the sensor node 110 and a storage that is a local storage module that stores information for identifying a converted event signal or a current location. Storage 314 is provided. In this case, the sensing data and the sensor data may be stored in the storage 314. The sensing data refers to an event, which is context information measured by the sensor 302, and may be expressed as a measurement value for temperature, humidity, vibration, and the like. The sensor data refers to information about the sensor node 110 itself, that is, a node name, ID, location, network address, and the like. The sensor data is preferably stored in the sensing information management database 132 in consideration of the memory limit of the sensor node 110.

The processing unit 300 may be implemented as a microminiature / low power micro controller unit (MCU) in an embodiment of the present invention. MCUs include CPU, program memory, SRAM, EEPROM, and ADC. Examples include Atmel's ATMega128L, TI's MSP430, and Microchip's PIC18F.

The transceiver 320 is provided as a communication module for transmitting data related to the event to the outside or receiving data transmitted from another sensor node 110.

The power unit 330 functions to supply energy to the units 300 to 320 provided inside the sensor node 110 by using a power generator 332 which is a battery. This, in turn, enables the smooth operation of the sensor node 110.

Next, a method of selecting the representative node 202 and a method of operating the cluster 200 for a predetermined time thereafter will be described.

In general, the LEACH protocol randomly circulates a representative node 202 that performs an energy-intensive function in order to distribute energy consumption fairly to all sensor nodes provided in the wireless sensor network system 100. In addition, in the LEACH protocol, the representative node 202 collects data in the cluster 200 and fusions them locally to reduce the overall communication cost. Hereinafter, this will be described in more detail with reference to the drawings. 4 is a time slot diagram of a LEACH protocol for explaining election and operation of a representative node in a wireless sensor network system according to a preferred embodiment of the present invention.

Referring to FIG. 4, the LEACH protocol consists of a time unit called round 400. Each round 400 consists of a setup time 410 in which the cluster 200 is configured, and a steady-state time 420 consisting of a plurality of TDMA frames. At the beginning of the set time 410, all sensor nodes determine whether they can be representative nodes 202 during the current round. The sensor nodes are then determined based on whether they were previously a representative node 202 and the number of ideal representative nodes 202 to be provided on the system 100. The sensor node 110, which has decided to become the representative node 202 during the current round, notifies neighboring sensor nodes. Then, the sensor nodes that receive this determine the representative node 202 based on parameters such as reception strength. This will be described using the equation as follows.

Where p is the percentage of sensor nodes that wish to be representative node 202, and r is the current round. G is a set of sensor nodes that are not selected as the representative node 202 in the last 1 / p round, and T (n) refers to a threshold. In addition, n indicates a specific sensor node. Initially at set time 410, sensor nodes select any number between 0 and 1, with sensor nodes any number lower than T (n) being selected as representative node 202.

When the representative node 202 is determined, a plurality of clusters are thus formed in the sensor field of the wireless sensor network system 100. When the cluster 200 is formed, the representative node 202 broadcasts the TDMA schedule to the general nodes indicating the data transmission order of the general nodes belonging to the initial state of the duration state 420. Then, normal nodes transmit data during their transmission slots (e.g., normal node i transmits data acquired during n time slot 430), and operate in sleep mode in other slots to save energy. Reduce unnecessary consumption

As such, in the LEACH protocol, collision / interference between general nodes 204 is avoided by using TDMA, and each representative node avoids collision / interference by using different spreading codes. However, in the implementation of the present invention, the method for the representative node 202 to elect and operate the cluster 200 is not limited thereto. For example, in the present invention, the manager node 120 may determine the cluster 200 and the representative node 202 in consideration of the location information and the energy reserve of the sensor node 110 (that is, the LEACH-C protocol). It is also possible to be used.

Meanwhile, in the present invention, the method of electing and operating the cluster 200 by the representative node 202 is the same as that of the LEACH protocol, but shows a difference in the data transmission method. It is also possible for a Sensitive Energy Efficient Sensor Network protocol to be applied to the system 100.

Next, a method of providing a higher level of security strength in data transmission by using a symmetric key encryption method and a public key encryption method in the wireless sensor network system 100 according to the present invention will be described.

5A is a flowchart illustrating a method of performing data communication using a symmetric key encryption method in a wireless sensor network system having a conventional hierarchical structure. 5B is a flowchart illustrating a method of performing data communication using a public key encryption method in a wireless sensor network system having a conventional hierarchical structure.

Referring to FIG. 5A, a first symmetric key to be used in communication between a conventional general node 500 and a conventional representative node 510 is generated in advance (ⓐ). In addition, a second symmetric key to be used in communication between the conventional representative node 510 and the think node 520 is generated in advance (ⓑ). Then, it is possible to encrypt the sensing information acquired by the conventional general node 500 using the first symmetric key and then transfer the sensing information to the conventional representative node 510 (©). In addition, it is possible to encrypt the sensing information received by the conventional representative node 510 using the second symmetric key and then transfer the sensing information to the sink node 520 (ⓓ).

Meanwhile, referring to FIG. 5B, the think node 520 generates a first public key and a second public key to be used for communication in advance, and transfers them to the conventional representative node 510 and the conventional general node 500, respectively ( Ⓔ, ⓕ). Then, it is possible to encrypt the sensing information acquired by the conventional general node 500 using the second public key and then transfer the sensing information to the conventional representative node 510 (ⓖ). Similarly, the conventional representative node 510 uses the first public key when transferring data to the think node 520 (ⓗ).

However, the conventional methods such as FIGS. 5A and 5B have not been capable of simultaneously maximizing energy efficiency and improving data security strength due to low power consumption of the sensor node. That is, the method of FIG. 5A is capable of maximizing the energy efficiency of the sensor node, but cannot improve the data security strength. On the other hand, the method of FIG. 5B is capable of improving data security strength, but not maximizing energy efficiency of the sensor node. Thus, the present invention is configured to simultaneously pursue the above two to provide an optimal environment for the wireless sensor network system 100. This will be described in more detail below.

FIG. 6A is a flowchart illustrating symmetric key generation for data encryption between a general node and a representative node in a wireless sensor network system according to a preferred embodiment of the present invention. 6B is a flowchart illustrating the generation of a public key for data encryption between a representative node and a manager node in a wireless sensor network system according to a preferred embodiment of the present invention.

In the wireless sensor network system 100 according to the present invention, in the case of intra-group data communication with low data density, data collected by adjacent general nodes at the time of an event may have similar contents. Therefore, even if some of the nodes are damaged in the process of transferring data to the representative node 202, the normal nodes are not severely damaged. On the other hand, if a large number of general nodes are provided in the cluster 200, the data communication amount generated between the general nodes and the representative node 202 increases. However, if a large amount of time is required to encrypt data (ie, longer than a given schedule), it is impossible for general nodes in the cluster 200 to transfer data to the representative node 202. Therefore, in the intra-group data communication, it is preferable to use a symmetric key encryption method that has low security strength but requires little time to encrypt.

On the other hand, in the inter-group data communication with high data density or data communication with the manager node 120, the representative node 202 receives the data from the general nodes to which the representative node belongs, and then provides the same to the manager node 120. However, if data to be transmitted to the representative node 202 to the manager node 120 is not smoothly transmitted, all data of the cluster 200 managed by the representative node 202 becomes useless and causes great damage. This is true even when the representative node 202 transfers data through the representative node 202 at the most recent distance of the manager node 120. On the other hand, since the number of representative nodes 202 is smaller than the number of general nodes provided in the cluster 200, the amount of data communication occurring between the representative node 202 and the manager node 120 is not so large. Therefore, in the inter-group data communication and the data communication with the manager node 120, although it takes a long time to encrypt, it is preferable that a public key encryption method having excellent security strength is used.

Therefore, in the present invention, symmetric key encryption method is used for intra-group data communication and public key encryption method is used for data communication between the group data communication with the manager node 120 and the energy efficiency of the sensor node 110 is maximized. It is characterized by simultaneously achieving the improvement of security strength. In particular, the symmetric key used in the symmetric key encryption method is characterized by improving the security strength than the conventional case by using a plurality of random numbers.

In the meantime, when the representative node 202 transmits data to the manager node 120, a method of directly transmitting the data through the representative node 202 located at the most recent distance of the manager node 120 may be used. It is also possible. This may have the effect of making it possible to further improve the data transfer success rate from the representative node 202 to the manager node 120.

With reference to FIG. 6A, communication of encrypted data develops between a general node 204 and a representative node 202. The general node 204 exchanges random number information with the representative node 202 in order to detect an event occurring in the surrounding area and transmit it to the representative node 202. In addition, the general node 204 generates a symmetric key based on the random number information, and uses it to develop data communication with the representative node 202. This will be described in more detail as follows. On the other hand, the random number information here refers to information about the random number necessary to encrypt the data.

First, the manager node 120 generates random number information (hereinafter, referred to as first random number information) and transmits it to all sensor nodes 110 provided in the wireless sensor network system 100 (㉠). In the present invention, the manager node 120 generates random number information on a predetermined time basis, but may generate only once in consideration of energy consumption of the sensor node 110.

Then, when the cluster 200 is formed (i), the general node 204 and the representative node 202 generate random information and send and receive them, respectively. That is, when the representative node 202 notifies the general nodes 204 that the representative node is selected as the representative node, the general node 204 expresses the intention to belong to the representative node 202 of the specific cluster 200. Send a combined signal (generally, the general node 204 joins the cluster 200 operated by the representative node 202 located at the most recent distance). At this time, the general node 204 sends the generated random number information (hereinafter referred to as second random number information) together (㉢). Then, the representative node 202 receiving this sends a schedule to the general node 204 created by the general nodes in the cluster 200 to prevent a collision that may occur during communication with the representative node 202. In this case, the representative node 202 also sends the random number information (hereinafter, referred to as third random number information) generated by itself (i). Then, the general node 204 and the representative node 202 generate a first communication encryption key (ie, a symmetric key) according to the present invention by using the first random number information, the second random number information, and the third random number information. Then, the general node 204 and the representative node 202 can use this to perform data communication with each other (㉤).

Since the encryption key for the first communication described above is based on the symmetric key, the algorithm is simple, and thus it is possible to reduce the power consumption of the sensor node 110 during the encryption process. In addition, since the first communication encryption key performs encryption using the first random information to the third random information, the security strength is improved compared to the conventional symmetric key. Therefore, when the general node 204 and the representative node 202 proceeds with data communication using the first communication encryption key according to the present invention, it is possible to have the advantages of both aspects.

In addition, since the value of the first communication encryption key is different for each general node 204, it is possible to ensure more secure data transmission. The reason why the first communication encryption key is different for each general node 204 is because the second random number information or the third random number information is different.

Meanwhile, referring to FIG. 6B, communication of encrypted data is also developed between the representative node 202 and the manager node 120. The sensor node 110 notifies the manager node 120 when it is selected as the representative node 202 (관리자). The manager node 120 then stores the private key and delivers the second communication encryption key (ie, the public key) associated with it to the representative node 202 (i). In this case, the manager node 120 preferably delivers the schedule to the representative node 202 together. This makes it possible for the representative node 202 to perform data communication with the manager node 120 without a communication conflict with another representative node 202. The representative node 202 encrypts the data to be transmitted using the provided second encryption key, and then transmits the data to the manager node 120 during the corresponding time (㉧). Meanwhile, in the present invention, the manager node 120 generates a second communication encryption key whenever the representative node 202 is changed. This is to receive data more securely. However, it is also possible for the manager node 120 to continuously use the second communication encryption key pre-generated in the embodiment of the present invention.

As described above, according to the present invention, as data density is high and low, an encryption key suitable for communication can be generated, thereby maximizing energy efficiency and improving security strength of the sensor node 110.

Next, a method of operating the wireless sensor network system 100 according to the preferred embodiment of the present invention configured as described above is as follows. 7 is a flowchart illustrating a method of operating a wireless sensor network system according to a preferred embodiment of the present invention.

Referring to FIG. 7, when the wireless sensor network system 100 according to the present invention is configured, sensing information acquired by the general nodes 204 is transferred to the manager node 120 according to the method proposed in FIGS. 6A and 6B. (S600, S602). That is, when a plurality of sensor nodes are installed in a certain area 112, the manager node 120 generates the first random number information and transmits the first random number information to all the sensor nodes. When the cluster 200 is formed, the representative node 202 and the general node 204 selected from the sensor nodes exchange second random number information and third random number information. The general nodes 204 and the representative node 202 use the same to generate a first communication encryption key. Then, the general node 204 encrypts the obtained sensing information using the first communication encryption key and then transfers the sensed information to the representative node 202.

Meanwhile, the representative node 202 decrypts the data received from the general nodes 204 and receives the second communication encryption key from the manager node 120. Then, the representative node 202 accumulates the decrypted data and encrypts it using the second communication encryption key, and transmits it to the manager node 120.

The manager node 120 decrypts data transmitted from the representative nodes to secure sensing information acquired by all sensor nodes. The manager node 120 transmits the obtained sensing information to the sensing information management server 130 (S604).

The sensing information management server 130 determines whether there is an abnormality phenomenon in the predetermined region 112 based on the information transmitted from the manager node 120 (S606). Then, when the indication of abnormality is confirmed, the sensing information management server 130 immediately transmits the fact to the user terminal 142 (S608). Such an estimate may be performed by the manager node 120 in the embodiment of the present invention. In this case, the manager node 120 transmits the fact to the user terminal 142 or directly through the sensing information management server 130.

The above description is merely illustrative of the technical idea of the present invention, and various modifications, changes, and substitutions may be made by those skilled in the art without departing from the essential characteristics of the present invention. will be. Accordingly, the embodiments disclosed in the present invention and the accompanying drawings are not intended to limit the technical spirit of the present invention but to describe the present invention, and the scope of the technical idea of the present invention is not limited by the embodiments and the accompanying drawings. . The scope of protection of the present invention should be interpreted by the following claims, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of the present invention.

As described above, according to the present invention, in a wireless sensor network having a hierarchical structure, data communication between nodes having low data density (that is, data communication between a sensor node and a representative node) is required for encryption / decryption. That is, a second communication encryption key (ie, a public key) is used for encryption / decryption for data communication (i.e., data communication between a specific representative node and another representative node or manager node) using a symmetric key) and high data density nodes. ), The sensor node can maximize energy efficiency and improve security strength.

Claims (18)

In the method for generating an encryption key in a wireless sensor network having a hierarchical structure, In the communication occurring between nodes with low data density, the encryption key is generated using a symmetric encryption algorithm, and in the communication occurring between nodes with high data density, the encryption key is generated using an asymmetric encryption algorithm. A method for generating an encryption key for communication according to data density in a wireless sensor network having a hierarchical structure. The method of claim 1, The communication between the nodes with low data density is communication between a general node detecting peripheral information in the wireless sensor network and a representative node managing a cluster to which the general node belongs. And a communication node configured to communicate between the representative node and a manager node managing all clusters provided in the wireless sensor network. The method of claim 2, The encryption key generated during the communication between the nodes having low data density is generated based on a random number generated by the general node, a random number generated by the representative node, and a random number generated by the manager node. Method of generating an encryption key for communication in accordance with the data density in the wireless sensor network having a. The method of claim 3, wherein The general node generates a cryptographic key for communication according to the data density in a wireless sensor network having a hierarchical structure, characterized in that it transmits a random number generated by the general node when transmitting the cluster subscription intention to the representative node. The method of claim 3, wherein The representative node generates a cryptographic key for communication according to the data density in the wireless sensor network having a hierarchical structure, wherein the representative node transmits a random number generated when the representative node transmits a schedule that records communication time between nodes to the general node. . The method of claim 3, wherein The manager node, when notifying that the representative node has been elected as a representative, delivers a public key generated by the method of generating an encryption key for communication according to the data density in a wireless sensor network having a hierarchical structure. The method of claim 3, wherein The representative node is a method for generating an encryption key for communication according to the data density in a wireless sensor network having a hierarchical structure, characterized in that the replacement after communication with all the general nodes provided in the cluster. In the communication method using an encryption key in a wireless sensor network having a hierarchical structure, (a) encrypting the data sensed using an encryption key generated by a general node using a symmetric encryption algorithm and transferring the detected data to a representative node; (b) decrypting the encrypted data by the representative node; (c) encrypting the decrypted data by using the encryption key generated by the representative node using an asymmetric encryption algorithm and transmitting the encrypted data to the manager node; (d) decrypting the encrypted data by the manager node and collecting the encrypted data and transmitting the collected data to a sensing information management server; (e) determining whether or not an abnormality has occurred in a specific region based on the data transmitted by the sensing information management server; And (f) notifying the user terminal of the fact determined by the sensing information management server; In the wireless sensor network having a hierarchical structure comprising a data communication method using a communication encryption key generated according to the data density. The method of claim 8, In step (d), (a1) determining whether an abnormality has occurred in a specific region based on the collected data by the manager node; In the wireless sensor network having a hierarchical structure characterized in that it further comprises a data communication method using a communication encryption key generated according to the data density. The method according to claim 8 or 9, The general node deploys communication through a general node located at the most recent distance of the representative node when direct communication with the representative node is impossible, and the representative node of the manager node when direct communication with the manager node is impossible. A method for data communication using a communication encryption key generated according to data density in a wireless sensor network having a hierarchical structure, characterized in that communication is carried out through a representative node located at a closest distance. The method according to claim 8 or 9, The encryption key in step (a) is a wireless sensor having a hierarchical structure, characterized in that generated based on a random number generated by the general node, a random number generated by the representative node, and a random number generated by the manager node A method of data communication using a communication encryption key generated according to data density in a network. The method of claim 11, The general node delivers a random number generated by itself when it transmits a cluster subscription intention to the representative node, and the representative node delivers a random number generated by itself when delivering a schedule recording communication time between nodes to the general node. The manager node uses a communication encryption key generated according to the data density in the wireless sensor network having a hierarchical structure, wherein the manager node transmits a public key generated by the manager node when the representative node is notified as the representative. How to communicate data. In a system in which a wireless sensor network having a hierarchical structure is implemented, A general node for detecting peripheral information; A representative node managing a cluster to which the general node belongs; And Manager node managing all clusters provided in the wireless sensor network Including but not limited to: The general node or the representative node generates an encryption key using a symmetric encryption algorithm based on a random number generated by the general node, a random number generated by the representative node, and a random number generated by the manager node. Wireless sensor network system having a hierarchical structure. The method of claim 13, The general node delivers a random number generated by the general node when it transmits the intention to join the cluster to the representative node, and the representative node receives a random number generated by the general node when delivering a schedule recording communication time between nodes to the general node. Wireless sensor network system having a hierarchical structure, characterized in that for transmitting. The method of claim 13, And the manager node delivers a public key generated by the manager node when notifying that the representative node has been selected as a representative. The method of claim 13, The manager node is a wireless sensor network system having a hierarchical structure, characterized in that receiving the data obtained by a plurality of general nodes through a representative node to determine whether or not an abnormal phenomenon has occurred in a specific region. The method according to any one of claims 13 to 15, A sensing information management server that receives data acquired by a plurality of general nodes through the representative node and the manager node and determines whether abnormality has occurred in a specific region based on the received data; And A user terminal receiving the facts determined by the sensing information management server so that the user can check them. Wireless sensor network system having a hierarchical structure further comprising. The method according to any one of claims 13 to 16, The general node deploys communication through a general node located at the most recent distance of the representative node when direct communication with the representative node is impossible, and the representative node of the manager node when direct communication with the manager node is impossible. Wireless sensor network system having a hierarchical structure characterized in that the communication is deployed through the representative node located in the most recent distance.

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