Safe communication method and system for low-power-consumption wireless network

Abstract

The invention provides a secure communication method and system for a low-power-consumption wireless network. And a global message sending cache set mechanism is provided, and the gateway can manage the messages which are not received, so that the data cannot be lost due to node dormancy. In combination with a timed task mechanism, the gateway can retransmit messages in a moderated manner at preset wake-up time or other appropriate time of the wireless nodes, so that the situation that the network load is increased due to too frequent retransmission, and then the performance of the whole system is affected is avoided; a key management system is introduced, and a gateway is responsible for applying and distributing working keys of wireless nodes in a unified manner. And the gateway obtains the working key which needs to be used at present through communication with the key management system, and distributes the working key to each node. The problem that the calculation amount is too large when the wireless node carries out asymmetric key negotiation is solved, the key management process of the node can be simplified, and the calculation and communication burden of the node is reduced; in order to prevent communication abnormity caused by secret key mismatching between the wireless node and the gateway, a secret key proofreading mechanism is designed in the process that the wireless node applies for a working secret key. The mechanism ensures that an encrypted communication link established between the node and the gateway is encrypted and decrypted using the correct key.

Description

Technical Field

[0001] The present invention relates to the field of wireless sensor networks and information security, and in particular to a secure communication method and system for low-power wireless networks. Background Art

[0002] Low-power wireless networks, such as Zigbee, WIA-PA, WirelessHART, etc., are widely used in smart homes, environmental monitoring, smart cities, industrial Internet of Things, etc.

[0003] Low-power wireless networks have the characteristics of resource limitation, dynamic topology, delay sensitivity and node dormancy. First, the processing power, memory and battery life of wireless nodes are limited, which requires that the designed communication protocols and security mechanisms should not be too complicated; second, wireless nodes frequently join and exit, and the topology structure is constantly changing, which increases the complexity of communication management and security protection; third, some application scenarios are highly sensitive to delays, and it is necessary to reduce communication delays as much as possible while ensuring safety; finally, nodes in low-power wireless networks usually have a dormancy mechanism, and wireless communication links are not always maintained, which puts forward new requirements for the reliability design of security protocols. Therefore, in low-power wireless networks, communication reliability, communication efficiency and device life are crucial to application scenarios.

[0004] Traditional secure communication methods have certain limitations:

[0005] 1) Asymmetric encryption is computationally expensive: Although asymmetric encryption is effective in traditional networks, it is computationally expensive on low-power devices and is generally not suitable for resource-constrained devices;

[0006] 2) Key negotiation: Traditional key negotiation methods have high requirements on computing power and communication bandwidth. Using them on low-power devices may lead to increased energy consumption or low communication efficiency.

[0007] 3) Inadequate security protocol design: Many existing security protocols do not fully consider the power consumption optimization problem in low-power networks, resulting in effective security solutions but consuming too many resources, reducing the battery life and communication efficiency of the device. Summary of the invention

[0008] In view of the deficiencies of the prior art, the present invention provides a secure communication method and system for low-power wireless networks. Considering the sleep mechanism of wireless nodes, a "global message sending cache set" is designed in the gateway, and the message is retransmitted in a controlled manner using a scheduled task to improve the message reachability rate; a key management system is introduced, and the working keys of the wireless nodes are uniformly applied for and allocated by the gateway to the key management system to solve the problem of large amount of calculation in asymmetric key negotiation; in the process of the wireless node applying for the working key, a key verification mechanism is designed to prevent communication abnormalities caused by mismatching the keys of the wireless node and the gateway; a symmetric encryption algorithm is used in the encrypted communication process between the wireless node and the gateway, which has a small amount of calculation and reduces the power consumption in the encryption and decryption calculation process.

[0009] The technical solution adopted by the present invention to achieve the above-mentioned purpose is:

[0010] A secure communication method for a low-power wireless network includes the following steps:

[0011] 1) Issue device-related files to wireless nodes offline;

[0012] 2) Register the wireless node in the wireless security management system;

[0013] 3) The gateway synchronizes wireless node information data with the wireless security management system;

[0014] 4) Base station and gateway synchronize access control policies;

[0015] 5) The wireless node associates with the base station and completes two-way identity authentication with the gateway;

[0016] 6) The wireless node applies for a working key from the gateway;

[0017] 7) Wireless nodes and gateways conduct two-way encrypted communication.

[0018] The step 1) comprises the following steps:

[0019] 1.1) Use the terminal to connect to the wireless node;

[0020] 1.2) Call the key generation interface of the wireless node to generate a device signature key pair and obtain the public key of the device signature key pair;

[0021] 1.3) Create a certificate request file based on the public key of the device signature key pair;

[0022] 1.4) In the certificate management system, submit the certificate request file to generate the device signature certificate, device encryption certificate, device encryption key pair digital envelope, CA root certificate, and CRL file;

[0023] 1.5) Use the terminal to import the device signature certificate, device encryption certificate, device encryption key pair digital envelope, CA root certificate, and CRL file to the wireless node.

[0024] The step 2) comprises the following steps:

[0025] 2.1) Enter the basic information of the wireless node in the wireless security management system, and import the device signature certificate and device encryption certificate of the wireless node;

[0026] 2.2) Select the wireless nodes that are allowed to access the network in the wireless security management system and generate access control policies for the wireless nodes.

[0027] The step 3) comprises the following steps:

[0028] 3.1) The gateway establishes a connection with the wireless security management system;

[0029] 3.2) The gateway sends a "Gateway Device Information Table Synchronization: Request" message to the wireless security management system;

[0030] 3.3) The wireless security management system determines whether the gateway has been registered. If the gateway has been registered in the wireless security management system, the execution continues; otherwise, the communication ends;

[0031] 3.4) The wireless security management system determines whether the gateway has been authenticated. If it has been authenticated, it continues to execute; otherwise, it ends the communication;

[0032] 3.5) The wireless security management system generates the complete set of "device information table" and sends the "gateway device information table synchronization: device information table" message to the gateway;

[0033] 3.6) After receiving the device information table, the gateway updates the device information table and returns a message "Gateway device information table synchronization: update successful" to the wireless security management system;

[0034] 3.7) The gateway sends a "Gateway Access Control Policy Table Synchronization: Request" message to the wireless security management system;

[0035] 3.8) The wireless security management system determines whether the gateway has been registered. If the gateway has been registered in the wireless security management system, the execution continues; otherwise, the communication ends;

[0036] 3.9) The wireless security management system determines whether the gateway has been authenticated. If it has been authenticated, it continues to execute; otherwise, it ends the communication;

[0037] 3.10) The wireless security management system generates a complete set of "Access Control Policy Tables" and sends a "Gateway Access Control Policy Table Synchronization: Access Control Policy Table" message to the gateway;

[0038] 3.11) After receiving the access control policy table, the gateway updates the access control policy table and returns a message "Gateway access control policy table synchronization: update successful" to the wireless security management system;

[0039] 3.12) The wireless security management system disconnects from the gateway.

[0040] The step 4) comprises the following steps:

[0041] 4.1) The base station sends a "base station access control policy table synchronization: request" message to the gateway;

[0042] 4.2) The gateway determines whether the base station complies with the access control policy. If it complies with the access control policy, the base station message is allowed to pass through and the execution continues. Otherwise, the communication ends.

[0043] 4.3) The gateway determines whether the base station has been registered. If the base station has been registered in the wireless security management system, the execution continues; otherwise, the communication ends;

[0044] 4.4) The gateway determines whether the base station has been authenticated. If so, the gateway continues to execute; otherwise, the gateway terminates the communication.

[0045] 4.5) The gateway generates a subset of the "Access Control Policy Table" and sends a "Base Station Access Control Policy Table Synchronization: Access Control Policy Table" message to the base station.

[0046] The step 5) comprises the following steps:

[0047] 5.1) The wireless node scans the wireless channel and obtains a list of available personal area networks;

[0048] 5.2) The wireless node selects the channel with the largest signal strength from the personal area network list as the optimal link quality indicator based on the signal strength of the channel, and completes the association with the base station with the optimal channel quality;

[0049] 5.3) The wireless node sends a "Wireless Node Security Access: Join Request" message to the gateway;

[0050] 5.4) The base station determines whether the wireless node complies with the access control policy. If it complies with the access control policy, the wireless node message is allowed to pass through and the execution continues. Otherwise, the communication ends.

[0051] 5.5) If the base station determines that the "Wireless Node Security Access: Join Request" message is not sent to the device itself, it forwards it to the gateway;

[0052] 5.6) The gateway determines whether the message content is reasonable. If the message content is reasonable, it continues to execute, otherwise, it ends the communication;

[0053] 5.7) The gateway determines whether the wireless node has been registered. If the wireless node has been registered in the wireless security management system, the execution continues; otherwise, the communication ends;

[0054] 5.8) The gateway determines whether the wireless node has been authenticated. If the wireless node has not completed authentication with the gateway, the gateway returns a "Wireless Node Security Access: Authentication Request (Gateway Signature Certificate)" message to the wireless node and saves the message to the "Global Message Sending Cache Collection";

[0055] 5.9) If the base station determines that the "Wireless Node Security Access: Authentication Request (Gateway Signature Certificate)" message is not sent to the device itself, it forwards it to the wireless node;

[0056] 5.10) The wireless node uses the CA root certificate to verify the legitimacy of the gateway signature certificate. If the signature verification is successful, the wireless node returns a "Wireless Node Security Access: Authentication Response (Wireless Node Signature Certificate)" message to the gateway and continues to execute. Otherwise, the communication ends.

[0057] 5.11) The base station determines whether the wireless node complies with the access control policy. If it complies with the access control policy, the wireless node message is allowed to pass through and the execution continues. Otherwise, the communication ends.

[0058] 5.12) The gateway determines whether the content of the message is reasonable. If so, it continues to execute, otherwise, it ends the communication;

[0059] 5.13) The gateway determines whether the wireless node has been registered. If the wireless node has been registered in the wireless security management system, the execution continues; otherwise, the communication ends;

[0060] 5.14) The gateway uses the CA root certificate to verify the legitimacy of the wireless node signature certificate. If the signature verification is successful, the gateway returns a "Wireless Node Security Access: Join Response (Access Successful)" message to the wireless node and deletes the corresponding authentication request message in the "Global Message Sending Cache Collection";

[0061] 5.15) The gateway records the wireless nodes that have passed the authentication in the device authentication table;

[0062] 5.16) If the base station determines that the "Wireless Node Security Access: Join Response (Access Successful)" message is not sent to the device itself, it is directly forwarded to the wireless node.

[0063] The step 6) comprises the following steps:

[0064] 6.1) The wireless node sends a message "Wireless node applies for working key: working key update request" to the key management system, obtains the wireless node device serial number, assembles the key application data, and signs the application data using the "signature key";

[0065] 6.2) The base station determines whether the wireless node complies with the access control policy. If it complies with the access control policy, the wireless node message is allowed to pass through and the execution continues. Otherwise, the communication ends.

[0066] 6.3) If the base station determines that the "Wireless Node Applying for Working Key: Working Key Update Request" message is not sent to the device itself, it forwards it to the gateway;

[0067] 6.4) The gateway determines whether the content of the base station message is reasonable. If the content of the message is reasonable, it continues to execute, otherwise, it ends the communication;

[0068] 6.5) The gateway determines whether the wireless node has been registered. If the wireless node has been registered in the wireless security management system, the execution continues; otherwise, the communication ends;

[0069] 6.6) The gateway determines whether the wireless node has been authenticated. If the wireless node and the gateway have completed authentication, the execution continues. Otherwise, an unauthenticated message is returned.

[0070] 6.7) The gateway converts the device serial number of the wireless node into a device identification, obtains the device signature certificate based on the device identification, and verifies the legitimacy of the signature in the request key message. If the signature verification result is correct, the execution continues, otherwise, the communication ends;

[0071] 6.8) After the gateway parses the "Wireless Node Applying for Working Key: Working Key Update Request" message, it calls the kmip interface to remotely access the key management system, and creates the data encryption key of the wireless node, encrypts and obtains the data encryption key of the wireless node, creates the data MAC key of the wireless node, and encrypts and obtains the data MAC key of the wireless node;

[0072] 6.9) The gateway assembles the encryption key ciphertext of the node data and the data MAC key ciphertext, constructs a "wireless node applies for working key: working key update response" message, and sends it to the wireless node;

[0073] 6.10) The gateway saves the assembled message into the "global message sending cache set";

[0074] 6.11) If the base station determines that the "Wireless Node Requests Working Key: Working Key Update Response" message is not sent to the device itself, it is directly forwarded to the wireless node;

[0075] 6.12) The wireless node verifies the legitimacy of the working key update response message. If the signature verification is successful, the execution continues; otherwise, the communication ends.

[0076] 6.13) The wireless node calls the cryptographic chip function interface, uses the encryption key to decrypt the private key, and imports the working key ciphertext including the data encryption key ciphertext and the data MAC key ciphertext;

[0077] 6.14) According to the import result, the data encryption key check value and the data MAC key check value are calculated, a working key update confirmation request is assembled, and a "wireless node applies for working key: working key update confirmation request" message is sent to the gateway;

[0078] 6.15) The base station determines whether the wireless node complies with the access control policy. If it complies with the access control policy, the wireless node message is allowed to pass through, and the execution continues;

[0079] 6.16) The base station determines that the message is not sent to the device itself, and forwards it to the gateway;

[0080] 6.17) The gateway determines whether the message content is reasonable. If the message content is reasonable, it continues to execute;

[0081] 6.18) The gateway determines whether the wireless node has been registered. If the wireless node has been registered in the wireless security management system, the execution continues; otherwise, the communication ends;

[0082] 6.19) The gateway determines whether the wireless node has been authenticated. If the wireless node and the gateway have completed authentication, the execution continues. Otherwise, an unauthenticated message is returned.

[0083] 6.20) The gateway parses the received message, and if it is a working key update confirmation request message, it deletes the corresponding working key update response message in the "global message sending cache set";

[0084] 6.21) The gateway converts the device serial number in the message into a device ID, obtains the device signature certificate based on the device ID, and verifies the legitimacy of the key application data signature. If the signature is correct, the execution continues; otherwise, the communication ends.

[0085] 6.22) The gateway calls the kmip interface to remotely access the key management system, and obtains the data encryption key and data MAC key of the corresponding wireless node from the key management system through encryption;

[0086] 6.23) The gateway calls the password card function and imports the working key ciphertext to the specified location;

[0087] 6.24) The gateway compares the consistency of the data encryption key check value and the data MAC key check value, and sends a "wireless node applies for working key: working key update confirmation response" message to the wireless node;

[0088] 6.25) When the base station determines that the "Wireless Node Applying for Working Key: Working Key Update Confirmation Response" message is not sent to the device itself, it is directly forwarded to the wireless node;

[0089] 6.26) The wireless node verifies the legitimacy of the working key update confirmation response message;

[0090] 6.27) The wireless node parses the working key update confirmation response message. If the check value is inconsistent, it re-applies for the key and ends the process directly. Otherwise, execute step 6.28);

[0091] 6.28) When the base station determines that the "Wireless Node Applying for Working Key: Working Key Update Confirmation Response" message is not sent to the device itself, it is directly forwarded to the wireless node.

[0092] The step 7) comprises the following steps:

[0093] 7.1) The wireless node calls the cryptographic chip function interface and uses the data encryption key to encrypt the data;

[0094] 7.2) The wireless node calls the cryptographic chip, generates a MAC interface, uses the data MAC key, and generates a data ciphertext MAC value;

[0095] 7.3) The wireless node assembles the encrypted data and its corresponding data ciphertext MAC value, and sends the assembled encrypted data to the gateway;

[0096] 7.4) The base station determines whether the wireless node complies with the access control policy. If it complies with the access control policy, the wireless node message is allowed to pass, and the execution continues;

[0097] 7.5) When the base station determines that the assembled encrypted data message is not sent to the device itself, it forwards it to the gateway;

[0098] 7.6) The gateway determines whether the message content is reasonable. If the message content is reasonable, it continues to execute;

[0099] 7.7) The gateway determines whether the wireless node has been registered. If the wireless node has been registered in the wireless security management system, the execution continues;

[0100] 7.8) The gateway determines whether the wireless node has been authenticated. If the wireless node and the gateway have completed authentication, the execution continues; otherwise, an unauthenticated message is returned;

[0101] 7.9) After receiving the assembled encrypted data, the gateway parses the short address and queries the key index corresponding to the node based on the short address;

[0102] 7.10) The gateway calls the verification MAC function interface of the password card to verify the integrity of the data ciphertext. If the ciphertext is judged to be complete, the execution continues;

[0103] 7.11) The gateway calls the password card data decryption function interface, uses the data encryption key, decrypts the data, and obtains the plain text;

[0104] 7.12) The gateway analyzes the message type. If the message is a write request message, it constructs a corresponding write response message and encrypts the application layer payload to assemble an encrypted message.

[0105] 7.13) The gateway sends a "gateway encrypted data: encrypted data" message to the wireless node;

[0106] 7.14) If the base station determines that the "Gateway Encrypted Data: Encrypted Data" message is not sent to the device itself, it is directly forwarded to the wireless node.

[0107] The processing of the global message sending buffer set comprises the following steps:

[0108] (1) Start the scheduled task after the gateway is started;

[0109] (2) After the timer expires, the scheduled task checks whether the message in the "global message sending cache set" has timed out. If the message has timed out, continue to step (3); otherwise, jump to step (2);

[0110] (3) Check the number of message retransmissions. If the number of retransmissions is greater than the threshold, delete the message from the "global message sending cache set". Otherwise, retransmit the message and increase the number of retransmissions by 1.

[0111] Secure communication system for low-power wireless networks, including:

[0112] A wireless node is built into a wireless access device and is used to provide the wireless access device with the ability to access the wireless network;

[0113] The base station is the access point of the wireless LAN network, which is used to forward the interactive data between the wireless nodes and the gateway;

[0114] The gateway, as the overall coordinator, is used to coordinate and allocate communication resources between base stations and wireless nodes;

[0115] Wireless security management system for managing wireless nodes, base stations and gateways;

[0116] Certificate management system, used for issuing, updating and canceling digital certificates throughout the life cycle of devices;

[0117] Key management system, used for full life cycle management of symmetric keys of various devices;

[0118] A cryptographic machine is used to provide key generation and cryptographic operation services for the key management system.

[0119] The present invention has the following beneficial effects and advantages:

[0120] 1. The present invention sets a "global message sending cache collection" in the gateway to temporarily store messages that have not been successfully sent because the wireless node is in a dormant state. Through this collection, the gateway can manage unreceived messages to ensure that data will not be lost due to node dormancy. Combined with the timed task mechanism, the gateway can retransmit messages in a controlled manner at the scheduled wake-up time of the wireless node or other appropriate times to avoid increasing network load due to too frequent retransmissions, thereby affecting the performance of the entire system. This mechanism effectively improves the reachability of messages while ensuring the stability and energy efficiency of the network;

[0121] 2. In encrypted communications on wireless networks, security and resource consumption often need to be weighed. Although asymmetric encryption is highly secure, it is not suitable for wireless nodes with limited resources due to its high computational complexity. To this end, a key management system is introduced, in which the gateway is responsible for applying for and allocating working keys for wireless nodes. The gateway obtains the working key currently required by communicating with the key management system and distributes it to each node. This not only solves the problem of excessive computational effort of wireless nodes during asymmetric key negotiation, but also simplifies the key management process of nodes and reduces the computational and communication burden of nodes.

[0122] 3. In order to prevent communication anomalies caused by key mismatch between wireless nodes and gateways, a key verification mechanism is designed in the process of wireless nodes applying for working keys. This mechanism ensures that the encrypted communication link established between the node and the gateway uses the correct key for encryption and decryption. Specifically, the key verification mechanism verifies the consistency of the key through a two-way confirmation process between the node and the gateway. Once a key mismatch is found, the system can automatically trigger the process of re-applying for the key or performing key synchronization, thereby avoiding data transmission failures or security risks caused by key asynchrony.

[0123] 4. In the encrypted communication process between wireless nodes and gateways, the use of symmetric encryption algorithms is an efficient solution. Compared with asymmetric encryption algorithms, symmetric encryption has a small amount of calculation and is suitable for resource-constrained wireless nodes. The use of symmetric encryption can not only greatly reduce the computational burden of nodes during encryption and decryption, but also effectively reduce power consumption. This is particularly critical to the battery life of wireless nodes, especially in low-power networks, where extending the working time of nodes is one of the core goals of the design. BRIEF DESCRIPTION OF THE DRAWINGS

[0124] Figure 1 It is a schematic diagram of the typical composition of the system;

[0125] Figure 2 It is a timing diagram for issuing device signature certificates and other files to wireless nodes offline;

[0126] Figure 3 is a timing diagram for registering a wireless node in a wireless security management system;

[0127] Figure 4 It is a timing diagram of data synchronization between the gateway and the wireless security management system;

[0128] Figure 5 It is a timing diagram of the access control strategy of the base station and the gateway synchronization;

[0129] Figure 6 It is a timing diagram of two-way authentication between wireless nodes and gateways;

[0130] Figure 7 It is a timing diagram of a wireless node applying for a working key from a gateway;

[0131] Figure 8 It is a timing diagram of two-way encrypted communication between wireless nodes and gateways. DETAILED DESCRIPTION

[0132] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0133] like Figure 1 As shown, the present invention relates to a secure communication system for low-power wireless networks. The system comprises wireless nodes, base stations, gateways, wireless security management systems, certificate management systems, key management systems, and cryptographic machines. In the present invention, the base stations and wireless nodes are in a one-to-many relationship.

[0134] The wireless node is built into the wireless access device and provides wireless communication capability for the wireless access device;

[0135] The base station is an access point of the wireless local area network and is responsible for forwarding the interactive data between the wireless node and the gateway;

[0136] The gateway acts as a general coordinator, responsible for coordinating and allocating communication resources of base stations and wireless nodes, and sending uplink and downlink data to designated devices;

[0137] The wireless security management system is responsible for managing wireless nodes, base stations and gateways, including device registration and deletion, wireless LAN device network status monitoring, etc.;

[0138] The certificate management system is responsible for the issuance, update and cancellation of digital certificates for various devices throughout their life cycle;

[0139] The key management system is responsible for the full life cycle management of symmetric keys of various devices, including key generation, key update, key storage, backup and tracing, deletion and destruction, etc., and provides a kmip standard access interface to the outside world;

[0140] The cryptographic machine is a cryptographic device that provides key generation and cryptographic operation services for the certificate management system.

[0141] like Figure 2 As shown, the offline issuance of device signature certificates and other documents to wireless nodes involved in the present invention involves terminals, wireless nodes and certificate management systems. The specific steps are as follows:

[0142] Step 101) Use the terminal to connect to the wireless node;

[0143] Step 102) calling the key generation interface of the wireless node to generate a device signature key pair and obtain the public key of the device signature key pair;

[0144] Step 103) Create a certificate request file based on the public key of the device signature key pair;

[0145] Step 104) In the certificate management system, submit the certificate request file to generate the device signature certificate, device encryption certificate, device encryption key pair digital envelope, CA root certificate, and CRL file;

[0146] Step 105) Use the terminal to import the device signature certificate, device encryption certificate, device encryption key pair digital envelope, CA root certificate, and CRL file into the wireless node.

[0147] like Figure 3 As shown, the present invention involves registering a wireless node in a wireless security management system, which involves a wireless security management system. The specific steps are as follows:

[0148] Step 201) Log in to the wireless security management system;

[0149] Step 202) Input the basic information of the wireless node in the system, and import the device signature certificate and device encryption certificate of the wireless node;

[0150] Step 203) Select wireless nodes that are allowed to access the network in the system and generate access control policies for the wireless nodes.

[0151] like Figure 4 As shown, the gateway and wireless security management system involved in the present invention synchronize data, involving the gateway and the wireless security management system. The specific steps are as follows:

[0152] Step 301) The gateway establishes a connection with the wireless security management system;

[0153] Step 302) The gateway sends a "Gateway Device Information Table Synchronization: Request" message to the wireless security management system;

[0154] Step 303) The wireless security management system determines whether the gateway has been registered. If the gateway has been registered in the wireless security management system, the execution continues; otherwise, the wireless security management system returns a "Gateway Device Information Table Synchronization: Gateway Not Registered" message to the gateway and jumps to step 312);

[0155] Step 304) The wireless security management system determines whether the gateway has been authenticated. If the authentication has been completed, the execution continues, otherwise the wireless security management system returns a "Gateway Device Information Table Synchronization: Gateway Not Authenticated" message to the gateway and jumps to step 312);

[0156] Step 305) The wireless security management system generates a complete set of "device information tables" and sends a "Gateway Device Information Table Synchronization: Device Information Table" message to the gateway;

[0157] Step 306) After receiving the device information table, the gateway updates the device information table and returns a "Gateway device information table synchronization: update successful" message to the wireless security management system;

[0158] Step 307) The gateway sends a "Gateway Access Control Policy Table Synchronization: Request" message to the wireless security management system;

[0159] Step 308) The wireless security management system determines whether the gateway has been registered. If the gateway has been registered in the wireless security management system, the execution continues; otherwise, the wireless security management system returns a "Gateway Access Control Policy Table Synchronization: Gateway Not Registered" message to the gateway and jumps to step 312);

[0160] Step 309) The wireless security management system determines whether the gateway has been authenticated. If the authentication has been completed, the execution continues, otherwise the wireless security management system returns a "Gateway Access Control Policy Table Synchronization: Gateway Not Authenticated" message to the gateway and jumps to step 312);

[0161] Step 310) The wireless security management system generates a complete set of "Access Control Policy Tables" and sends a "Gateway Access Control Policy Table Synchronization: Access Control Policy Table" message to the gateway;

[0162] Step 311) After receiving the access control policy table, the gateway updates the access control policy table and returns a "Gateway Access Control Policy Table Synchronization: Update Successful" message to the wireless security management system;

[0163] Step 312) The wireless security management system disconnects from the gateway.

[0164] like Figure 5 As shown, the base station and gateway synchronization access control strategy involved in the present invention involves the base station and the gateway. The specific steps are as follows:

[0165] Step 401) The base station sends a "base station access control policy table synchronization: request" message to the gateway;

[0166] Step 402) The gateway determines whether the base station complies with the access control policy. If the base station message is allowed to pass, the execution continues; otherwise, the process jumps to step 406);

[0167] Step 403) The gateway determines whether the base station has been registered. If the base station has been registered in the wireless security management system, the execution continues, otherwise the gateway returns a "base station access control policy table synchronization: base station is not registered" message to the base station and jumps to step 406);

[0168] Step 404) The gateway determines whether the base station has been authenticated. If the authentication has been completed, the execution continues, otherwise the gateway returns a "base station access control policy table synchronization: base station not authenticated" message to the base station and jumps to step 406);

[0169] Step 405) The gateway generates a subset of the "access control policy table" and sends a "base station access control policy table synchronization: access control policy table" message to the base station;

[0170] Step 406) ends.

[0171] like Figure 6 As shown, the bidirectional identity authentication between the wireless node and the gateway involved in the present invention involves the wireless node, the base station and the gateway. The specific steps are as follows:

[0172] Step 501) The wireless node scans the wireless channel to obtain a list of available personal area networks;

[0173] Step 502) The wireless node selects the best link quality indicator from the personal area network list and completes the association with the base station with the best channel quality;

[0174] Step 503) The wireless node sends a "Wireless Node Security Access: Join Request" message to the gateway;

[0175] Step 504) The base station determines whether the wireless node complies with the access control policy. If the wireless node message is allowed to pass, the execution continues; otherwise, the execution jumps to step 517);

[0176] Step 505) The base station determines that the message is not sent to the device itself, and forwards it to the gateway;

[0177] Step 506) The gateway determines whether the message content is reasonable. If the message content is reasonable, continue to execute, otherwise jump to step 517);

[0178] Step 507) The gateway determines whether the wireless node has been registered. If the wireless node has been registered in the wireless security management system, the execution continues, otherwise the gateway returns a "Wireless Node Security Access: Join Response (Wireless Node Not Registered)" message to the wireless node and jumps to step 516);

[0179] Step 508) The gateway determines whether the wireless node has been authenticated. If the wireless node has not completed authentication with the gateway, the gateway returns a "Wireless Node Security Access: Authentication Request (Gateway Signature Certificate)" message to the wireless node and saves the message to the "Global Message Sending Cache Collection", otherwise the gateway returns a "Wireless Node Security Access: Join Response (Wireless Node Access Successful)" message to the wireless node and jumps to step 516);

[0180] Step 509) The base station determines that the message is not sent to the device itself, and forwards it to the wireless node;

[0181] Step 510) The wireless node uses the "CA public key" to verify the legitimacy of the gateway's "signature certificate". If the signature verification is successful, the wireless node returns a "Wireless Node Security Access: Authentication Response (Wireless Node Signature Certificate)" message to the gateway and continues to execute, otherwise the wireless node returns a "Wireless Node Security Access: Authentication Response (Signature Verification Failed)" message to the gateway and jumps to step 517);

[0182] Step 511) The base station determines whether the wireless node complies with the access control policy. If the wireless node message is allowed to pass, the execution continues; otherwise, the execution jumps to step 517);

[0183] Step 512) The gateway determines whether the message content is reasonable. If it is reasonable, continue to execute, otherwise jump to step 517);

[0184] Step 513) The gateway determines whether the wireless node has been registered. If the wireless node has been registered in the wireless security management system, the execution continues, otherwise the gateway returns a "Wireless Node Security Access: Join Response (Wireless Node Not Registered)" message to the wireless node and jumps to step 516);

[0185] Step 514) The gateway uses the "CA public key" to verify the legitimacy of the "signature certificate" of the wireless node. If the signature verification is successful, the gateway returns a "Wireless Node Security Access: Join Response (Access Success)" message to the wireless node, and removes the corresponding authentication request message in the "Global Message Sending Cache Set", otherwise the gateway returns a "Wireless Node Security Access: Join Response (Signature Verification Failed)" message to the wireless node and jumps to step 517);

[0186] Step 515) The gateway records the wireless nodes that have passed the authentication in the device authentication table;

[0187] Step 516) The base station determines that the message is not sent to the device itself, and directly forwards it to the wireless node. Jump to step 517);

[0188] Step 517) ends.

[0189] The specific steps of processing the global message sending buffer set are as follows:

[0190] Step 518) After the gateway is started, the scheduled task will be started;

[0191] Step 519) After the timer expires, the task checks whether the message in the "global message sending cache set" has timed out. If the message has timed out, continue to execute, otherwise jump to step 519);

[0192] Step 520) Check the number of message retransmissions. If the number of retransmissions is greater than 3, delete the message from the "global message sending cache set". Otherwise, retransmit the message and increase the number of retransmissions by 1.

[0193] like Figure 7 As shown, the wireless node involved in the present invention applies for a working key from a gateway, which involves a wireless node, a base station, a gateway and a key management system. The specific steps are as follows:

[0194] Step 601) The wireless node sends a "wireless node application for working key: working key update request" message to the key management system. In this process, the wireless node device serial number is obtained, key application data is assembled, and the application data is signed using a "signature key";

[0195] Step 602) The base station determines whether the wireless node complies with the access control policy. If the wireless node message is allowed to pass, the execution continues; otherwise, the execution jumps to step 629);

[0196] Step 603) The base station determines that the message is not sent to the device itself, and forwards it to the gateway;

[0197] Step 604) The gateway determines whether the content of the base station message is reasonable. If the content of the message is reasonable, the execution continues, otherwise jumps to step 629);

[0198] Step 605) The gateway determines whether the wireless node has been registered. If the wireless node has been registered in the wireless security management system, the execution continues, otherwise the gateway returns a "wireless node applies for a working key: working key update response (wireless node is not registered)" message to the wireless node and jumps to step 628);

[0199] Step 606) The gateway determines whether the wireless node has been authenticated. If the wireless node has not completed authentication with the gateway, the gateway returns a message "Wireless node applies for working key: working key update response (wireless node not authenticated)" to the wireless node and jumps to step 628). Otherwise, continue to execute;

[0200] Step 607) The gateway converts the device serial number of the wireless node into a device identifier. According to the device identifier, the device signature certificate is obtained to verify the legitimacy of the signature in the key request message. If the signature verification result is incorrect, the gateway sends a "Wireless Node Requests Working Key: Working Key Update Response (Incomplete Data)" to the wireless node and jumps to step 628), otherwise continue to execute;

[0201] Step 608) After the gateway parses the "wireless node applies for working key: working key update request" message, it calls the kmip interface to remotely access the key management system, including creating a data encryption key for the wireless node, encrypting and obtaining the data encryption key for the wireless node, creating a data MAC key for the wireless node, and encrypting and obtaining the data MAC key for the wireless node;

[0202] Step 609) Assemble the encryption key ciphertext of the node data and the data MAC key ciphertext, and the gateway sends a "wireless node application for working key: working key update response" to the wireless node;

[0203] Step 610) The gateway saves the assembled message into the "global message sending cache set";

[0204] Step 611) The base station determines that the message is not sent to the device itself and directly forwards it to the wireless node;

[0205] Step 612) The wireless node verifies the legitimacy of the working key update response message. If the signature verification fails, it sends a "wireless node applies for working key: working key update request (signature verification failed)" to the gateway and jumps to step 629). Otherwise, continue to execute;

[0206] Step 613) The wireless node calls the cryptographic chip function, uses the encryption key to decrypt the private key, and imports the working key ciphertext, including the data encryption key ciphertext and the data MAC key ciphertext;

[0207] Step 614) assemble a working key update confirmation request based on the import result and the calculated data encryption key check value and data MAC key check value, and initiate a "wireless node applies for working key: working key update confirmation request" message to the gateway;

[0208] Step 615) The base station determines whether the wireless node complies with the access control policy. If the wireless node message is allowed to pass, the execution continues; otherwise, the execution jumps to step 629);

[0209] Step 616) The base station determines that the message is not sent to the device itself, and forwards it to the gateway;

[0210] Step 617) The gateway determines whether the message content is reasonable. If the message content is reasonable, continue to execute, otherwise jump to step 629);

[0211] Step 618) The gateway determines whether the wireless node has been registered. If the wireless node has been registered in the wireless security management system, the process continues. Otherwise, the gateway returns a message "Wireless node applies for working key: working key update confirmation response (wireless node is not registered)" to the wireless node and jumps to step 628);

[0212] Step 619) The gateway determines whether the wireless node has been authenticated. If the wireless node has not completed authentication with the gateway, the gateway returns a message "Wireless node applies for working key: working key update confirmation response (wireless node is not authenticated)" to the wireless node and jumps to step 628). Otherwise, continue to execute;

[0213] Step 620) parses the corresponding message. If it is a working key update confirmation request message, remove the corresponding working key update response message in the "global message sending cache set";

[0214] Step 621) The gateway converts the device serial number into a device identifier, obtains the device signature certificate based on the device identifier, and verifies the legitimacy of the key application data signature. If the signature verification is incorrect, the gateway sends a "Wireless Node Application for Working Key: Working Key Update Confirmation Response (Incomplete Data)" to the node, otherwise continue to execute;

[0215] Step 622) encrypting and obtaining the data encryption key of the gateway to the key management system, and encrypting and obtaining the data MAC key of the gateway;

[0216] Step 623) The gateway calls the password card function to import the working key ciphertext to the specified location, including the data encryption key ciphertext and the data MAC key ciphertext;

[0217] Step 624) The gateway compares the consistency of the data encryption key check value and the data MAC key check value. The gateway sends a "wireless node application for working key: working key update confirmation response (result: success / check value inconsistency)" to the wireless node;

[0218] Step 625) The base station determines that the message is not sent to the device itself and directly forwards it to the wireless node;

[0219] Step 626) The wireless node verifies the legitimacy of the working key update confirmation response message;

[0220] Step 627) The wireless node parses the working key update confirmation response message. If the check value is inconsistent, it re-applies for the key and jumps to step 629);

[0221] Step 628) The base station determines that the message is not sent to the device itself, and directly forwards it to the wireless node. Jump to step 629);

[0222] Step 629) ends.

[0223] The specific steps of processing the global message sending buffer set are as follows:

[0224] Step 630) After the gateway is started, the scheduled task will be started;

[0225] Step 631) After the timer expires, the task checks whether the message in the "global message sending cache set" has timed out. If the message has timed out, continue to execute, otherwise jump to step 631);

[0226] Step 632) Check the number of message retransmissions. If the number of retransmissions is greater than 3, delete the message from the "global message sending cache set". Otherwise, retransmit the message and increase the number of retransmissions by 1.

[0227] like Figure 8 As shown, the wireless node and the gateway involved in the present invention perform two-way encrypted communication, involving the wireless node, base station and gateway. The specific steps are as follows:

[0228] Step 701) The wireless node calls the cryptographic module data encryption interface and uses the data encryption key to encrypt the data;

[0229] Step 702) The wireless node calls the cryptographic module data to generate a MAC interface, uses the data MAC key, and generates a data ciphertext MAC value;

[0230] Step 703) The wireless node sends the assembled encrypted data to the gateway;

[0231] Step 704) The base station determines whether the wireless node complies with the access control policy. If the wireless node message is allowed to pass, the execution continues; otherwise, the execution jumps to step 716);

[0232] Step 705) The base station determines that the message is not sent to the device itself, and forwards it to the gateway;

[0233] Step 706) The gateway determines whether the message content is reasonable. If the message content is reasonable, continue to execute, otherwise jump to step 716);

[0234] Step 707) The gateway determines whether the wireless node has been registered. If the wireless node has been registered in the wireless security management system, the execution continues, otherwise the gateway returns a "Gateway Encrypted Data: Encrypted Data (Wireless Node Not Registered)" message to the wireless node and jumps to step 715);

[0235] Step 708) The gateway determines whether the wireless node has been authenticated. If the wireless node has not completed authentication with the gateway, the gateway returns a "Gateway Encrypted Data: Encrypted Data (Wireless Node Not Authenticated)" message to the wireless node and jumps to step 715). Otherwise, continue to execute;

[0236] Step 709) After receiving the sensitive data, the gateway parses the short address and queries the key index corresponding to the node according to the short address;

[0237] Step 710) Call the password card data verification MAC interface to verify the integrity of the data ciphertext. If it is determined that the ciphertext is incomplete, jump to step 714). Otherwise, continue to execute;

[0238] Step 711) The gateway calls the password card data decryption interface, uses the data encryption key, decrypts the data, and obtains the plain text;

[0239] Step 712) The gateway analyzes the message type. If the message is a write request message, it constructs a corresponding write response message and encrypts the application layer payload to assemble an encrypted message;

[0240] Step 713) The gateway sends a "Gateway Encrypted Data: Encrypted Data" message to the wireless node. Jump to step 715);

[0241] Step 714) The gateway sends a "Gateway Encrypted Data: Encrypted Data (Data Incomplete)" message to the wireless node. Jump to step 715);

[0242] Step 715) The base station determines that the message is not sent to the device itself and directly forwards it to the wireless node;

[0243] Step 716) ends.

Claims

1. A secure communication method for low-power wireless networks, characterized in that: The following steps are involved: 1) Issue device-related files to wireless nodes offline; 2) Register the wireless node in the wireless security management system; 3) The gateway synchronizes wireless node information data with the wireless security management system; 4) Base station and gateway synchronize access control policies; 5) The wireless node associates with the base station and completes two-way identity authentication with the gateway; 6) The wireless node applies for a working key from the gateway; 7) Wireless nodes and gateways conduct two-way encrypted communication.

2. The secure communication method for low-power wireless networks according to claim 1, characterized in that: The step 1) comprises the following steps: 1.1) Use the terminal to connect to the wireless node; 1.2) Call the key generation interface of the wireless node to generate a device signature key pair and obtain the public key of the device signature key pair; 1.3) Create a certificate request file based on the public key of the device signature key pair; 1.4) In the certificate management system, submit the certificate request file to generate the device signature certificate, device encryption certificate, device encryption key pair digital envelope, CA root certificate, and CRL file; 1.5) Use the terminal to import the device signature certificate, device encryption certificate, device encryption key pair digital envelope, CA root certificate, and CRL file to the wireless node.

3. The secure communication method for low-power wireless networks according to claim 1, characterized in that: The step 2) comprises the following steps: 2.1) Enter the basic information of the wireless node in the wireless security management system, and import the device signature certificate and device encryption certificate of the wireless node; 2.2) Select the wireless nodes that are allowed to access the network in the wireless security management system and generate access control policies for the wireless nodes.

4. The secure communication method for low-power wireless networks according to claim 1, characterized in that: The step 3) comprises the following steps: 3.1) The gateway establishes a connection with the wireless security management system; 3.2) The gateway sends a "Gateway Device Information Table Synchronization: Request" message to the wireless security management system; 3.3) The wireless security management system determines whether the gateway has been registered. If the gateway has been registered in the wireless security management system, the execution continues; otherwise, the communication ends; 3.4) The wireless security management system determines whether the gateway has been authenticated. If it has been authenticated, it continues to execute; otherwise, it ends the communication; 3.5) The wireless security management system generates the complete set of "device information table" and sends the "gateway device information table synchronization: device information table" message to the gateway; 3.6) After receiving the device information table, the gateway updates the device information table and returns a "Gateway device information table synchronization: update successful" message to the wireless security management system; 3.7) The gateway sends a "Gateway Access Control Policy Table Synchronization: Request" message to the wireless security management system; 3.8) The wireless security management system determines whether the gateway has been registered. If the gateway has been registered in the wireless security management system, the execution continues; otherwise, the communication ends; 3.9) The wireless security management system determines whether the gateway has been authenticated. If it has been authenticated, it continues to execute; otherwise, it ends the communication; 3.10) The wireless security management system generates the full set of "Access Control Policy Table" and sends the "Gateway Access Control Policy Table Synchronization: Access Control Policy Table" message to the gateway; 3.11) After receiving the access control policy table, the gateway updates the access control policy table and returns a "Gateway access control policy table synchronization: update successful" message to the wireless security management system; 3.12) The wireless security management system disconnects from the gateway.

5. The secure communication method for low-power wireless networks according to claim 1, characterized in that: The step 4) comprises the following steps: 4.1) The base station sends a "base station access control policy table synchronization: request" message to the gateway; 4.2) The gateway determines whether the base station complies with the access control policy. If it complies with the access control policy, the base station message is allowed to pass through and the execution continues. Otherwise, the communication ends. 4.3) The gateway determines whether the base station has been registered. If the base station has been registered in the wireless security management system, the execution continues; otherwise, the communication ends; 4.4) The gateway determines whether the base station has been authenticated. If so, the gateway continues to execute; otherwise, the gateway terminates the communication. 4.5) The gateway generates a subset of the "Access Control Policy Table" and sends a message "Base Station Access Control Policy Table Synchronization: Access Control Policy Table" to the base station.

6. The secure communication method for low-power wireless networks according to claim 1, characterized in that: The step 5) comprises the following steps: 5.1) The wireless node scans the wireless channel and obtains a list of available personal area networks; 5.2) The wireless node selects the channel with the largest signal strength from the personal area network list as the optimal link quality indicator based on the signal strength of the channel, and completes the association with the base station with the optimal channel quality; 5.3) The wireless node sends a "Wireless Node Security Access: Join Request" message to the gateway; 5.4) The base station determines whether the wireless node complies with the access control policy. If it complies with the access control policy, the wireless node message is allowed to pass through and the execution continues. Otherwise, the communication ends. 5.5) If the base station determines that the "Wireless Node Security Access: Join Request" message is not sent to the device itself, it forwards it to the gateway; 5.6) The gateway determines whether the message content is reasonable. If the message content is reasonable, it continues to execute, otherwise, it ends the communication; 5.7) The gateway determines whether the wireless node has been registered. If the wireless node has been registered in the wireless security management system, the execution continues; otherwise, the communication ends; 5.8) The gateway determines whether the wireless node has been authenticated. If the wireless node has not completed authentication with the gateway, the gateway returns a "Wireless Node Security Access: Authentication Request (Gateway Signature Certificate)" message to the wireless node and saves the message to the "Global Message Sending Cache Collection"; 5.9) If the base station determines that the "Wireless Node Security Access: Authentication Request (Gateway Signature Certificate)" message is not sent to the device itself, it forwards it to the wireless node; 5.10) The wireless node uses the CA root certificate to verify the legitimacy of the gateway signature certificate. If the signature verification is successful, the wireless node returns a "Wireless Node Security Access: Authentication Response (Wireless Node Signature Certificate)" message to the gateway and continues to execute. Otherwise, the communication ends. 5.11) The base station determines whether the wireless node complies with the access control policy. If it complies with the access control policy, the wireless node message is allowed to pass through and the execution continues. Otherwise, the communication ends. 5.12) The gateway determines whether the content of the message is reasonable. If so, it continues to execute, otherwise, it ends the communication; 5.13) The gateway determines whether the wireless node has been registered. If the wireless node has been registered in the wireless security management system, the execution continues; otherwise, the communication ends; 5.14) The gateway uses the CA root certificate to verify the legitimacy of the wireless node signature certificate. If the signature verification is successful, the gateway returns a "Wireless Node Security Access: Join Response (Access Successful)" message to the wireless node and deletes the corresponding authentication request message in the "Global Message Sending Cache Collection"; 5.15) The gateway records the wireless nodes that have passed the authentication in the device authentication table; 5.16) If the base station determines that the "Wireless Node Security Access: Join Response (Access Successful)" message is not sent to the device itself, it is directly forwarded to the wireless node.

7. The secure communication method for low-power wireless networks according to claim 1, characterized in that: The step 6) comprises the following steps: 6.1) The wireless node sends a message "Wireless node applies for working key: working key update request" to the key management system, obtains the wireless node device serial number, assembles the key application data, and signs the application data using the "signature key"; 6.2) The base station determines whether the wireless node complies with the access control policy. If it complies with the access control policy, the wireless node message is allowed to pass through and the execution continues. Otherwise, the communication ends. 6.3) If the base station determines that the "Wireless Node Applying for Working Key: Working Key Update Request" message is not sent to the device itself, it forwards it to the gateway; 6.4) The gateway determines whether the content of the base station message is reasonable. If the content of the message is reasonable, it continues to execute, otherwise, it ends the communication; 6.5) The gateway determines whether the wireless node has been registered. If the wireless node has been registered in the wireless security management system, the execution continues; otherwise, the communication ends; 6.6) The gateway determines whether the wireless node has been authenticated. If the wireless node and the gateway have completed authentication, the execution continues. Otherwise, an unauthenticated message is returned. 6.7) The gateway converts the device serial number of the wireless node into a device identification, obtains the device signature certificate based on the device identification, and verifies the legitimacy of the signature in the request key message. If the signature verification result is correct, the execution continues, otherwise, the communication ends; 6.8) After the gateway parses the "Wireless Node Applying for Working Key: Working Key Update Request" message, it calls the kmip interface to remotely access the key management system, and creates the data encryption key of the wireless node, encrypts and obtains the data encryption key of the wireless node, creates the data MAC key of the wireless node, and encrypts and obtains the data MAC key of the wireless node; 6.9) The gateway assembles the encryption key ciphertext of the node data and the data MAC key ciphertext, constructs a "wireless node applies for working key: working key update response" message, and sends it to the wireless node; 6.10) The gateway saves the assembled message to the "global message sending cache set"; 6.11) If the base station determines that the "Wireless Node Requests Working Key: Working Key Update Response" message is not sent to the device itself, it is directly forwarded to the wireless node; 6.12) The wireless node verifies the legitimacy of the working key update response message. If the signature verification is successful, the execution continues; otherwise, the communication ends. 6.13) The wireless node calls the cryptographic chip function interface, uses the encryption key to decrypt the private key, and imports the working key ciphertext including the data encryption key ciphertext and the data MAC key ciphertext; 6.14) According to the import result, the data encryption key check value and the data MAC key check value are calculated, a working key update confirmation request is assembled, and a "wireless node applies for working key: working key update confirmation request" message is sent to the gateway; 6.15) The base station determines whether the wireless node complies with the access control policy. If it complies with the access control policy, the wireless node message is allowed to pass through, and the execution continues; 6.16) The base station determines that the message is not sent to the device itself, and forwards it to the gateway; 6.17) The gateway determines whether the message content is reasonable. If the message content is reasonable, it continues to execute; 6.18) The gateway determines whether the wireless node has been registered. If the wireless node has been registered in the wireless security management system, the execution continues; otherwise, the communication ends; 6.19) The gateway determines whether the wireless node has been authenticated. If the wireless node and the gateway have completed authentication, the execution continues. Otherwise, an unauthenticated message is returned. 6.20) The gateway parses the received message, and if it is a working key update confirmation request message, it deletes the corresponding working key update response message in the "global message sending cache set"; 6.21) The gateway converts the device serial number in the message into a device ID, obtains the device signature certificate based on the device ID, and verifies the legitimacy of the key application data signature. If the signature is correct, the execution continues; otherwise, the communication ends. 6.22) The gateway calls the kmip interface to remotely access the key management system, and obtains the data encryption key and data MAC key of the corresponding wireless node from the key management system through encryption; 6.23) The gateway calls the password card function and imports the working key ciphertext to the specified location; 6.24) The gateway compares the consistency of the data encryption key check value and the data MAC key check value, and sends a "wireless node applies for working key: working key update confirmation response" message to the wireless node; 6.25) When the base station determines that the "Wireless Node Applying for Working Key: Working Key Update Confirmation Response" message is not sent to the device itself, it is directly forwarded to the wireless node; 6.26) The wireless node verifies the legitimacy of the working key update confirmation response message; 6.27) The wireless node parses the working key update confirmation response message. If the check value is inconsistent, it re-applies for the key and ends the process directly. Otherwise, execute step 6.28); 6.28) When the base station determines that the "Wireless Node Applying for Working Key: Working Key Update Confirmation Response" message is not sent to the device itself, it is directly forwarded to the wireless node.

8. The secure communication method for low-power wireless networks according to claim 1, characterized in that: The step 7) comprises the following steps: 7.1) The wireless node calls the cryptographic chip function interface and uses the data encryption key to encrypt the data; 7.2) The wireless node calls the cryptographic chip, generates a MAC interface, uses the data MAC key, and generates a data ciphertext MAC value; 7.3) The wireless node assembles the encrypted data and its corresponding data ciphertext MAC value, and sends the assembled encrypted data to the gateway; 7.4) The base station determines whether the wireless node complies with the access control policy. If it complies with the access control policy, the wireless node message is allowed to pass, and the execution continues; 7.5) When the base station determines that the assembled encrypted data message is not sent to the device itself, it forwards it to the gateway; 7.6) The gateway determines whether the message content is reasonable. If the message content is reasonable, it continues to execute; 7.7) The gateway determines whether the wireless node has been registered. If the wireless node has been registered in the wireless security management system, the execution continues; 7.8) The gateway determines whether the wireless node has been authenticated. If the wireless node and the gateway have completed authentication, the execution continues; otherwise, an unauthenticated message is returned; 7.9) After receiving the assembled encrypted data, the gateway parses the short address and queries the key index corresponding to the node based on the short address; 7.10) The gateway calls the verification MAC function interface of the password card to verify the integrity of the data ciphertext. If the ciphertext is judged to be complete, the execution continues; 7.11) The gateway calls the password card data decryption function interface, uses the data encryption key, decrypts the data, and obtains the plain text; 7.12) The gateway analyzes the message type. If the message is a write request message, it constructs a corresponding write response message and encrypts the application layer payload to assemble an encrypted message. 7.13) The gateway sends a "gateway encrypted data: encrypted data" message to the wireless node; 7.14) If the base station determines that the "Gateway Encrypted Data: Encrypted Data" message is not sent to the device itself, it is directly forwarded to the wireless node.

9. The secure communication method for low-power wireless networks according to claim 7, characterized in that: The processing of the global message sending buffer set comprises the following steps: (1) Start the scheduled task after the gateway is started; (2) After the timer expires, the scheduled task checks whether the message in the "global message sending cache set" has timed out. If the message has timed out, continue to step (3); otherwise, jump to step (2); (3) Check the number of message retransmissions. If the number of retransmissions is greater than the threshold, delete the message from the "global message sending cache set". Otherwise, retransmit the message and increase the number of retransmissions by 1.

10. A secure communication system for low-power wireless networks, characterized in that: include: A wireless node is built into a wireless access device and is used to provide the wireless access device with the ability to access the wireless network; The base station is the access point of the wireless LAN network, which is used to forward the interactive data between the wireless nodes and the gateway; The gateway, as the overall coordinator, is used to coordinate and allocate communication resources between base stations and wireless nodes; Wireless security management system for managing wireless nodes, base stations and gateways; Certificate management system, used for issuing, updating and canceling digital certificates throughout the life cycle of devices; Key management system, used for full life cycle management of symmetric keys of various devices; A cryptographic machine is used to provide key generation and cryptographic operation services for the key management system.

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