1 Introduction Wireless Sensor Network (WSN) is a self-organizing network that works together to achieve a specific task through a large number of low-cost, resource-constrained sensor node devices. It is a revolution in information perception and acquisition technology and one of the most important technologies of the 21st century. It monitors climate, ambient temperature, lighting, humidity, etc., air pollution level monitoring, building structural integrity monitoring, home environment anomalies, airport or stadium chemical, biological threat detection and forecast In other respects, WSN will be an economical alternative with broad application prospects. Sensor networks bring hope for real-time data collection and processing for deploying large-scale networks in complex environments. However, at the same time, WSN is usually deployed in an unattended and uncontrollable environment. In addition to various threats such as information leakage, information tampering, replay attacks, and denial of service faced by general wireless networks, WSN also faces sensor nodes. The attacker physically manipulates and acquires all the information stored in the sensor node to control the threat of part of the network. It is impossible for users to accept and deploy a sensor network that does not solve security and privacy issues. Therefore, when designing WSN protocol and software, we must fully consider the security issues that WSN may face and integrate security mechanisms into system design. Only in this way can the widespread application of sensor networks be promoted. Otherwise, the sensor network can only be deployed in a limited and controlled environment. This is the ultimate goal of the sensor network - achieving universal computing and becoming one of the people's lives. An important way is to violate. A good security mechanism design is based on the deep analysis of the threats, network characteristics, etc., and the sensor network is no exception. This paper will deeply analyze the characteristics of wireless sensor networks and the security they may face. Threats and research and discussion on their corresponding security measures. 2. Analysis of sensor network characteristics WSN is a large-scale distributed network, which is often deployed in unattended and unfavorable environments. In most cases, sensor nodes are used at one time, which determines that the sensor nodes are inexpensive and extremely resource-intensive. Restricted wireless communication equipment [2], its characteristics are mainly reflected in the following aspects: (1) limited energy: energy is the most important constraint condition limiting the capability and life of the sensing node, the existing sensor nodes They are powered by standard AAA or AA batteries and cannot be recharged. (2) Limited computing power: The sensor node CPU generally only has 8 bit, 4 MHz to 8 MHz processing capability. (3) Limited storage capacity: The sensing node generally includes three forms of memory, namely RAM, program memory, and working memory. The RAM is used to store temporary data during operation, generally not exceeding 2k bytes; the program memory is used to store operating systems, applications, and security functions, and the working memory is used to store acquired sensor information. These two types of memory are generally only available. Dozens of kilobytes. (4) Limited communication range: In order to save energy consumption during signal transmission, the transmission energy of the RF module of the sensing node is generally between 10mW and 100mW, and the transmission range is limited to 100m to 1km. (5) Anti-mite modification: The sensor node is a low-cost, loosely-structured, open network device. Once the attacker acquires the sensor node, it can easily obtain and modify the key information and program code stored in the sensor node. Wait. In addition, before most sensor networks are deployed, their network topology is unpredictable. At the same time, the role of the entire network topology and sensor nodes in the network changes frequently, so unlike wired networks and most wireless networks. In this way, the network device is completely configured, and the range of pre-configuration of the sensor nodes is limited. Many network parameters and keys are formed after the sensor nodes negotiate after deployment. According to the above characteristics analysis of wireless sensors, wireless sensor networks are vulnerable to various threats and attacks such as physical manipulation of sensing nodes, eavesdropping of sensing information, denial of service attacks, and leakage of private information. According to the characteristics of WSN, the following describes the classification and description of the potential security threats faced by WSN. 3. Threat analysis and countermeasures 3.1 Physical manipulation of sensor nodes In the future, sensor networks generally have hundreds or thousands of sensing nodes. It is difficult to monitor and protect each node. Therefore, each node is a potential attack point, and both attackers can perform physical and logical attacks. In addition, sensors are typically deployed in unattended environments, which makes it easier for attackers to capture sensor nodes. When the sensor node is captured, the attacker can modify or acquire the information or code in the sensor node through the programming interface (JTAG interface). According to the literature [3], the attacker can use simple tools (computer, UISP). Free software) can transfer all the information in EEPROM, Flash and SRAM to the computer in less than one minute. Through the assembly software, the acquired information can be easily converted into an assembly file format for analysis and transmission. The confidential information such as the program code, routing protocol, and key stored by the node can be modified, and the program code can be modified and loaded into the sensing node. Obviously, the current common sensor node has a large security vulnerability. Through this vulnerability, an attacker can easily obtain confidential information in the sensor node and modify the program code in the sensor node, such as making the sensor node The identity ID, so that the identity is communicated in the sensor network by multiple identities. In addition, the attack can also be performed by acquiring information such as a key and a code stored in the sensor node, thereby forging or disguising as a legitimate node to join the sensor network. in. Once a part of the nodes in the sensor network are controlled, the attacker can launch a variety of attacks, such as listening to information transmitted in the sensor network, issuing fake routing information or transmitting fake sensor information to the sensor network, and performing denial of service attacks. Wait. Countermeasure: Since the sensor node is easily physically manipulated, it is an unavoidable security problem for the sensor network. Other technical solutions must be used to improve the security performance of the sensor network. For example, the identity authentication of nodes and nodes is performed before communication; a new key agreement scheme is designed, so that even if a small number of nodes are manipulated, the attacker cannot or hardly derive the key information of other nodes from the acquired node information. Wait. In addition, the security performance of the node itself can be improved by authenticating the legality of the sensor node software. 3.2 Information Eavesdropping According to the characteristics of wireless propagation and network deployment, attackers can easily obtain sensitive or private information through transmission between nodes. For example, in a scenario where indoor temperature and lighting are monitored through a wireless sensor network, wireless receivers deployed outdoors can obtain The temperature and light information sent by the indoor sensor; the same attacker can also know the indoor information by monitoring the transmission of information between the indoor and outdoor nodes, thereby revealing the living habits of the owner. Countermeasure: Encrypting the transmitted information can solve the eavesdropping problem, but it requires a flexible and robust key exchange and governance solution. The key management scheme must be easily deployed and suitable for the sensor node resources. In addition, the key management scheme must also It is guaranteed that when some nodes are manipulated (so that the attacker can obtain the information of the generated session key stored in this node), the security of the entire network will not be destroyed. Due to the limited memory resources of the sensing nodes, it is impractical to achieve end-to-end security between most nodes in the sensor network. However, the encryption of the information between the hops and the hops can be implemented in the sensor network, so that the sensing node only needs to share the key with the neighboring node. In this case, even if the attacker captures a communication node, it only affects the security between adjacent nodes. However, when an attacker sends a fake routing message by manipulating a node, it affects the routing topology of the entire network. The solution to this problem is a robust routing protocol. Another method is multipath routing, which transfers part of the information over multiple paths and reorganizes at the destination. 3.3 Privacy issues The sensor network is used for collecting information as the main purpose. The attacker can obtain these sensitive information by eavesdropping, adding fake and illegal nodes, etc. If the attacker knows how to obtain limited information related information from multiple information, then the attacker It is possible to derive valid information from a large amount of information obtained. The problem of privateness in general sensors is not to obtain information that is unlikely to be collected through the sensor network. Instead, the attacker obtains a large amount of information by remotely monitoring the WSN, and analyzes the privateness problem according to a specific algorithm. Therefore, the attacker does not need physical contact with the sensor node, which is a low-risk, anonymous way to obtain private information. Remote monitoring also enables a single attacker to simultaneously obtain information about the transmissions of multiple nodes. Countermeasures: It is the best way to ensure that the sensory information in the network can only be accessed by trusted entities. This can be achieved through data encryption and access control. Another method is to limit the granularity of information sent by the network. Because the more specific the information, the more likely it is to disclose privacy. For example, a cluster node can achieve data anonymization by aggregating a large amount of information received from neighboring nodes and transmitting only the processing result. 3.4 Denial of Service Attack (DOS) DOS attacks are primarily used to disrupt the availability of the network, reducing or reducing any events that perform the network or the ability of the system to perform a desired function. Such as trying to interrupt, subvert or destroy the sensor network, in addition to hardware failures, software bugs, resource exhaustion, environmental conditions, etc. [4]. Here we mainly consider loopholes at the protocol and design level. Determining whether an error or a series of errors is caused by an intentional DOS attack is very difficult, especially in large-scale networks, because the sensor network itself has a relatively high single node failure rate. DOS attacks can occur at the physical layer, such as channel blocking, which may include maliciously interfering with the transmission of protocols in the network or physically damaging the sensing nodes in the network. The attacker can also initiate an attack that quickly consumes the energy of the sensing node. For example, a large amount of useless information is continuously sent to the target node, and the target node consumes energy to process the information and transmits the information to other nodes. If the attacker captures the sensor node, he can also spoof or pretend to be a legitimate node to initiate these DOS attacks. For example, it can generate a circular route to exhaust the energy of the nodes in the loop. There is no fixed way to defend against DOS attacks, which varies with the attacker's attack method. Some frequency hopping and spread spectrum techniques can be used to alleviate network congestion problems. Proper authentication prevents the insertion of useless information into the network. However, these protocols must be very effective, otherwise it will be used as a means of DOS attacks. For example, using a digital signature based on an asymmetric cryptosystem can be used for information authentication, but creating and verifying a signature is a computationally slow, energy-intensive calculation. An attacker can introduce a large amount of this information into the network. Effectively implement DOS attacks. 4. Summary Security is a key issue in the design of a good sensor network. Without adequate protection of confidentiality, privacy, integrity, and measures against DOS and other attacks, sensor networks cannot be widely used. It can only be limited. Implemented in a controlled environment, which will seriously affect the application prospects of sensor networks. In addition, when considering the security problem of the sensor network and selecting the corresponding security mechanism, it must be designed according to the network characteristics and application occasions in the design stage of the protocol and software. Trying to increase the security function of the system afterwards is usually confirmed as not. Successful or weak. Dsp Speaker,New Professional Speaker,Performance Speaker With Dsp,Active Speaker For Outdoor NINGBO RFUN AUDIO TECHNOLOGY CO.,LTD , https://www.mosensound.com