Lightweight DTLS protocol optimization and dual-mode link secure transmission method

Abstract

The invention is suitable for the technical field of power internet of things security communication, and relates to a lightweight DTLS protocol optimization and dual-mode link secure transmission method, which is simple in process and convenient to operate, and realizes protocol lightweight by simplifying a DTLS handshake process and adapting to a lightweight encryption algorithm; through a link-key dynamic binding mechanism, a DTLS session key is associated with a PLC / RF link state, so that re-handshake during link switching is avoided; and the data transmission security is ensured by combining forward error correction and integrity verification. According to the invention, the handshake message is reduced by 40%, the computing power occupation is reduced by 35%, the link switching delay is less than or equal to 50ms, the IPv6 protocol and the DL / T645 power protocol are supported, the safety communication requirements of terminals such as low-voltage transformer area electricity meters and photovoltaic inverters are met, the method is compatible with an electric red operating system, and the reliability and the safety of dual-mode link transmission are improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of power Internet of Things secure communication, and particularly relates to a lightweight DTLS protocol optimization and a dual-mode link secure transmission method. BACKGROUND

[0002] With the promotion of new power system construction, the number of low-voltage transformer area power terminals (such as electric meters and charging piles) has increased rapidly, but such terminals generally have resource limitations of "low computing power and small storage". The traditional DTLS protocol has three major pain points: first, the handshake process is complex (6-8 frames of messages are required), which occupies a large amount of computing power and bandwidth of the terminal; second, the encryption algorithm (such as RSA2048) is computationally intensive, resulting in high terminal power consumption; third, when switching between PLC / RF dual-mode links, a new handshake is required, which can have a delay of hundreds of milliseconds, affecting real-time services (such as load scheduling); fourth, the key and the link are not bound, and a single link leak can lead to a security risk in the entire network. DTLS protocol optimization is mostly focused on general Internet of Things devices and does not customize for the resource characteristics and service needs of power terminals, and lacks collaborative design with dual-mode links.

[0003] Patent application with publication number CN119382881A provides a transformer area distributed photovoltaic communication system based on an improved DTLS protocol, which includes a client and a server. The client and the server build a communication connection based on an improved certificateless DTLS handshake protocol. After the communication connection is completed, the client and the server interact with distributed photovoltaic data. The improved certificateless DTLS handshake protocol extends the mechanism for exchanging public key information between the client and the server on the original DTLS protocol. The private key of the client and the server includes two parts, one of which is generated by a private key generator according to the IDs of the two, and the other is randomly generated by itself according to system parameters. The encryption algorithm of the improved DTLS protocol in this patent application is intensive and computationally complex, with high power consumption, which has the disadvantages of the prior art system.

[0004] Therefore, how to provide a lightweight DTLS optimization scheme suitable for power terminals and a dual-mode secure transmission mechanism has become the key to solving the communication security of low-voltage transformer areas. SUMMARY

[0005] In view of the deficiencies of the prior art, the purpose of the present application is to provide a lightweight DTLS protocol optimization method to solve the problems of high computing power occupation of DTLS protocol in power terminals (resource-limited), large re-handshake delay when switching between dual-mode (PLC / RF) links, and difficulty in balancing security and real-time performance in the prior art. In addition, the present application also provides a dual-mode link secure transmission method.

[0006] To solve the above technical problems, the present application adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a lightweight DTLS protocol optimization method, comprising the following steps:

[0008] S1. Merge the ClientHello and KeyExchange messages of the DTLS handshake into a single frame message, omitting redundant extended fields and retaining only the encryption suite negotiation and session ID fields required by the power terminal;

[0009] S2. Lightweight encryption combination is selected to replace the traditional RSA+AES combination;

[0010] S3. A terminal identity pre-authentication mechanism is introduced. After the power terminal is authenticated for the first time, the validity period of the stored session ticket is extended to 24 hours. When accessing again, the session key can be reused directly without having to go through the complete handshake process again.

[0011] Furthermore, the encryption combination in S2 is SM4 symmetric encryption + SM2 asymmetric encryption + SM3 hash algorithm.

[0012] Secondly, the present invention also provides a dual-mode link secure transmission method, comprising the following steps:

[0013] S10. The power terminal collects the SNR, bit error rate and connectivity parameters of the PLC / RF link in real time and generates a link health matrix.

[0014] S20. Generate a master key based on the DTLS protocol, and derive a PLC-specific subkey and an RF-specific subkey based on the link health matrix to achieve dynamic binding between the key and the link;

[0015] S30. The master node broadcasts a signaling message containing the network number and encryption suite through the optimized DTLS protocol; the slave node initiates a network access request based on the pre-stored identity certificate, and the master node allocates a dual-mode subkey after verification.

[0016] S40: After the terminal data is encrypted with the corresponding link subkey, a message authentication code based on SM3 is attached, and it is transmitted in parallel via PLC / RF dual-mode.

[0017] S50. When a link failure is detected, the terminal automatically switches to the backup link and generates a new link key through a subkey fast derivation algorithm without the need for a re-handshake.

[0018] Furthermore, in S10, the length of the simplified handshake message is ≤256 bytes, adapting to the resource limitations of the power terminal.

[0019] Furthermore, in S20, the parameters of the link health matrix include the SNR, bit error rate, and link connectivity of the PLC / RF, and the parameter acquisition period is 100ms.

[0020] Furthermore, the SNR threshold is ≥60dB, the bit error rate threshold is ≤10 to the power of -5, and the link connectivity is a binary identifier of 0 or 1.

[0021] Furthermore, in S50, the subkey fast generation algorithm is generated iteratively based on the master key and link ID using the SM3 hash algorithm, with a generation time of ≤10ms, and the subkey is dynamically updated according to the link status.

[0022] Furthermore, in S40, forward error correction coding is introduced during data transmission. When the link error rate is ≤10 to the power of -3, automatic data error correction is achieved without retransmission.

[0023] Furthermore, the power terminal supports the IPv6 protocol stack and the DL / T645 power protocol. The optimized DTLS protocol is directly integrated into the secure communication component of the Elec-Tech operating system, and is compatible with the terminal's plug-and-play functionality.

[0024] Furthermore, in S50, the switching delay is ≤50ms.

[0025] The lightweight DTLS protocol optimization and dual-mode link secure transmission method provided by this invention has at least the following advantages compared with the prior art:

[0026] Existing technologies such as DTLS suffer from high computational cost in resource-constrained power terminals, significant handshake delays during dual-mode (PLC / RF) link switching, and difficulties in balancing security and real-time performance. This invention offers a simple and convenient process. It achieves protocol lightweighting by simplifying the DTLS handshake process and adapting to lightweight encryption algorithms. A dynamic "link-key" binding mechanism associates the DTLS session key with the PLC / RF link status, avoiding handshake re-handshakes during link switching. Forward error correction and integrity verification ensure secure data transmission. This invention reduces handshake messages by 40%, computational cost by 35%, and link switching latency to ≤50ms. It supports IPv6 and DL / T645 power protocols, meeting the secure communication needs of terminals such as low-voltage distribution meters and photovoltaic inverters. It is also compatible with the Elec-Tech operating system, improving the reliability and security of dual-mode link transmission. Attached Figure Description

[0027] To more clearly illustrate the solution of the present invention, a brief introduction will be given to the drawings used in the description of the embodiments below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0028] Figure 1A flowchart illustrating a lightweight DTLS protocol optimization method provided in this embodiment of the invention;

[0029] Figure 2 A flowchart of a dual-mode link secure transmission method provided in an embodiment of the present invention;

[0030] Figure 3 This is a schematic diagram illustrating the optimization of the DTLS protocol in the handshake process in a lightweight DTLS protocol optimization and dual-mode link secure transmission method provided in an embodiment of the present invention.

[0031] Figure 4 This is a schematic diagram illustrating the optimization of the DTLS protocol in the handshake process in a lightweight DTLS protocol optimization and dual-mode link secure transmission method provided in an embodiment of the present invention.

[0032] Figure 5 This is a diagram illustrating the dual-mode link secure transmission mechanism in a lightweight DTLS protocol optimization and dual-mode link secure transmission method provided in an embodiment of the present invention.

[0033] Figure 6 This is a schematic diagram of the secure networking and data transmission process in a lightweight DTLS protocol optimization and dual-mode link secure transmission method provided in an embodiment of the present invention;

[0034] Figure 7 This invention provides a hardware and protocol configuration diagram for a lightweight DTLS protocol optimization and dual-mode link secure transmission method.

[0035] Figure 8 This is a performance comparison chart of algorithms in a lightweight DTLS protocol optimization and dual-mode link secure transmission method provided in an embodiment of the present invention. Detailed Implementation

[0036] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Preferred embodiments of the invention are shown in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the invention.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0038] This invention provides a lightweight DTLS protocol optimization method, applied to the secure data transmission of multiple services in a low-voltage distribution area ("source-network-load-storage"), comprising the following steps:

[0039] S1. Merge the ClientHello and KeyExchange messages of the DTLS handshake into a single frame message, omitting redundant extended fields and retaining only the encryption suite negotiation and session ID fields required by the power terminal;

[0040] S2. Lightweight encryption combination is selected to replace the traditional RSA+AES combination;

[0041] S3. A terminal identity pre-authentication mechanism is introduced. After the power terminal is authenticated for the first time, the validity period of the stored session ticket is extended to 24 hours. When accessing again, the session key can be reused directly without having to go through the complete handshake process again.

[0042] This invention solves the problems of high computing power consumption, large handshake delay during dual-mode (PLC / RF) link switching, and difficulty in balancing security and real-time performance in the existing DTLS protocol.

[0043] This invention provides a lightweight DTLS protocol optimization method, applied to the secure data transmission process of multiple services in a low-voltage distribution area, such as... Figure 1 As shown, in this embodiment, the lightweight DTLS protocol optimization method includes the following steps:

[0044] S1. Simplified handshake process: The "ClientHello" and "KeyExchange" messages of the DTLS handshake are merged into a single frame message, and redundant extended fields (such as ALPN and SNI) are omitted, retaining only the encryption suite negotiation and session ID fields required by the power terminal.

[0045] S2. Encryption Algorithm Adaptation: A lightweight encryption combination (SM4 symmetric encryption + SM2 asymmetric encryption + SM3 hash algorithm) is selected to replace the traditional RSA+AES combination, reducing computing power consumption.

[0046] S3. Session reuse optimization: The "terminal identity pre-authentication" mechanism is introduced. After the power terminal is authenticated for the first time, the validity period of the stored session ticket is extended to 24 hours. When accessing again, the session key can be reused directly without having to go through the complete handshake process again.

[0047] This invention also provides a dual-mode link secure transmission method based on the lightweight DTLS protocol optimization method described in the above embodiments, applied to the secure data transmission process of multiple services in the "source-network-load-storage" system of low-voltage distribution areas, combined with... Figures 1 to 8 In this embodiment, the dual-mode link secure transmission method of the lightweight DTLS protocol optimization method includes the following steps:

[0048] S10, Dual-mode link status monitoring: The power terminal collects the SNR, bit error rate and connectivity parameters of the PLC / RF link in real time and generates a "link health matrix".

[0049] Specifically, in this embodiment, the length of the simplified handshake message in step S10 is ≤256 bytes, which is 40% less than the standard DTLS handshake message, thus adapting to the resource limitations of the power terminal (ARM Cortex-M4 core, main frequency ≤150MHz).

[0050] S20. Dynamic Key Binding: A master key is generated based on the DTLS protocol, and a PLC-specific subkey and an RF-specific subkey are derived based on the "link health matrix" to achieve dynamic binding between the key and the link.

[0051] Specifically, in this embodiment, the “link health matrix” in step S20 includes the following dimensional parameters: SNR of PLC / RF (threshold ≥ 60dB), bit error rate (threshold ≤ 10 to the power of -5), and link connectivity (0-1 binary identifier), with a parameter acquisition period of 100ms.

[0052] S30, Secure Networking: The master node (CCO) broadcasts a signaling message containing the network number and encryption suite through the optimized DTLS protocol; the slave node (STA) initiates a network access request based on the pre-stored identity certificate, and the master node assigns a dual-mode subkey after verification.

[0053] S40. Data transmission: After the terminal data is encrypted with the corresponding link subkey, a message authentication code (HMAC) based on SM3 is attached, and it is transmitted in parallel via PLC / RF dual-mode.

[0054] Specifically, in this embodiment, forward error correction coding (RS(127,119)) is introduced during the data transmission process in step S40. When the link bit error rate is ≤10 to the power of negative 3, automatic data error correction can be achieved without retransmission.

[0055] S50, Link Switching: When a link failure is detected, the terminal automatically switches to the backup link and generates a new link key through the "subkey fast derivation algorithm". No handshake is required and the switching delay is ≤50ms.

[0056] Specifically, in this embodiment, the "subkey fast generation algorithm" in step S50 is generated by SM3 hash iteration based on the master key and the link ID (PLC is 0x01, RF is 0x02), with a generation time of ≤10ms, and the subkey is dynamically updated with the link status (update cycle 5s).

[0057] Furthermore, in this embodiment, the power terminal supports the IPv6 protocol stack and the DL / T645 power protocol. The optimized DTLS protocol can be directly integrated into the "Secure Communication Components" of the Elec-Tech operating system, and is compatible with the terminal's plug-and-play functionality.

[0058] In this embodiment, the DTLS protocol is optimized from three aspects—process, algorithm, and reuse—to address resource constraints of power terminals. The specific details are as follows:

[0059] This invention addresses application scenarios with limited power terminal resources by systematically optimizing the DTLS protocol across three levels: process, algorithm, and reuse mechanism. Regarding the handshake process, the three traditional DTLS messages—"ClientHello," "KeyExchange," and "ChangeCipherSpec"—are merged into a single "PowerDTLS-Hello" message. Only core fields such as the cipher suite list (no more than three types), session ID, and terminal identification (e.g., IMEI) are retained, reducing the message length from the standard 512 bytes to less than 256 bytes, significantly lowering communication overhead. At the algorithm level, the invention fully adopts the lightweight national cryptographic algorithm combination recommended by the State Cryptography Administration, including SM4 (128-bit symmetric encryption), SM2 (256-bit asymmetric encryption), and SM3 (256-bit hash algorithm). Compared to the traditional "RSA2048+AES256" scheme, this reduces computing power consumption by 35% and power consumption by 20%. In terms of session management, a pre-authentication mechanism based on the unique identifier of the terminal (such as the meter asset number) is introduced, and the session ticket issued by the master node is extended to 24 hours. When the terminal reconnects, it can directly reuse the existing session key with the ticket, simplifying the handshake process from 6 steps to 2 steps and greatly reducing the latency from 500ms to 50ms, effectively improving connection efficiency and terminal energy efficiency.

[0060] In this embodiment, based on the optimized DTLS protocol, the present invention designs a dual-mode transmission mechanism with dynamic "key-link" binding, the specific process of which is as follows:

[0061] The optimized DTLS protocol's dynamic key-link binding dual-mode transmission mechanism aims to improve the communication reliability and security of power terminals in complex environments. This mechanism first uses the terminal's built-in link monitoring module to collect physical parameters of the PLC (Power Line Communication) and RF (Radio Frequency) links in real-time at 100ms intervals, including coupling circuit status, carrier frequency, signal strength, and channel interference. Based on the health score calculation formula (health score = 0.6 × signal-to-noise ratio + 0.3 × (1 - bit error rate) + 0.1 × connectivity), a link health score of 0-100 is dynamically generated. Regarding key management, the master key (MK) is generated by the optimized DTLS handshake process and stored in a tamper-proof secure storage area. Based on this master key and the link identifiers (PLC=0x01, RF=0x02), the SM3 hash algorithm iterates three times to derive a subkey (MK-P) specifically for the PLC link and a subkey (MK-R) specifically for the RF link. When the link health score changes by more than 10 points, the system automatically triggers the regeneration of the subkey to avoid the potential risk of leakage caused by long-term key use.

[0062] During secure networking and data transmission, the Central Coordinating Node (CCO) broadcasts PowerDTLS signaling frames (containing network identifier, encryption suite, and master node certificate) in dual-mode. Terminal devices (STAs) receive these frames and initiate network access requests using pre-installed Southern Power Grid CA-issued certificates. After verification, the CCO distributes the corresponding subkeys MK-P and MK-R. During data transmission, the terminal dynamically selects the transmission link based on service priority—high-priority services use dual-mode parallel transmission, with data encrypted using the corresponding link's subkey and appended with a 16-byte SM3-HMAC checksum to ensure data confidentiality and integrity. For link failure scenarios, when a link's health score falls below 40, the system immediately triggers seamless switching: first, the backup link and its subkey are activated; then, a temporary subkey is rapidly derived within 10ms based on the master key MK and the new link identifier; and finally, forward error correction coding (RS(127,119)) is used to recover data packets lost during the switching process, ultimately achieving a smooth switching experience seamless for the user. This mechanism effectively integrates dynamic key management and multi-link adaptive transmission, improving system reliability and security.

[0063] In this embodiment, to ensure the stable operation of the optimized DTLS protocol on resource-constrained power terminals, a specific hardware platform and software configuration are adopted. The terminal hardware core uses a microprocessor based on the ARM Cortex-M4 architecture with a main frequency of 150MHz, and is equipped with 64KB of RAM and 512KB of Flash memory, providing the necessary computing power and storage space for protocol processing. Regarding the communication interface, the terminal integrates a power line carrier (PLC) coupling circuit, supports a 1.8MHz carrier frequency, and is also equipped with a 2.4GHz radio frequency (RF) module, providing the hardware foundation for dual-mode communication. At the protocol level, the optimized DTLS handshake message length is compressed to 220 bytes, and encryption and authentication are performed using the "SM2-SM4-SM3" national cryptographic algorithm suite. The session ticket validity period is set to 24 hours to support long-term reuse, and a 5-second subkey dynamic derivation cycle is set in conjunction with link status monitoring to improve security. The entire system is powered by HarmonyOS for Power V2.0, which integrates a dedicated "secure communication component". It not only natively supports the optimized DTLS protocol stack, but also achieves seamless integration with IPv6 networks and the DL / T645 electricity information collection protocol, meeting the specific needs of the power industry for communication security and reliability.

[0064] Example 1

[0065] In an application scenario where a distribution area contains 400 smart meters (STAs) and 1 concentrator (CCO), all equipped with the system of this invention, the optimized DTLS protocol and dual-mode transmission mechanism were fully verified. In this scenario, the PLC link is responsible for routine meter reading services, while the RF link is dedicated to transmitting high-priority fault alarm information.

[0066] In terms of protocol optimization, resource consumption has been significantly reduced: the standard DTLS protocol originally required ≥60% CPU and 32KB RAM, but after optimization, CPU utilization has been reduced to below 25%, and RAM consumption has been reduced to 15KB. Handshake efficiency has also been greatly improved, with the initial handshake latency reduced from 500ms to 200ms, and under the session reuse mechanism, the latency has been further reduced to 50ms.

[0067] In secure transmission verification, the system operated stably: smart meters used the MK-P subkey to encrypt electricity consumption data and transmitted it via the PLC, while simultaneously using the MK-R subkey to encrypt key alarm information and send it via the RF link. Both services achieved a 100% HMAC verification pass rate. When a PLC link failure was artificially simulated, the terminal detected a drop in link health to 30 points and quickly switched to the RF link within 45ms, generating a new subkey through a fast key derivation algorithm, ensuring a data transmission success rate of no less than 99.5%. Regarding security, third-party testing showed that the optimized protocol effectively resists replay attacks and man-in-the-middle attacks, with the encrypted data cracking difficulty reaching level 2. 128 This significantly enhances the overall security of the system.

[0068] The lightweight DTLS protocol optimization and dual-mode link secure transmission method described in the above embodiments addresses the shortcomings of existing technologies. Existing technologies suffer from high computational cost in resource-constrained power terminals, significant handshake delays during dual-mode (PLC / RF) link switching, and difficulties in balancing security and real-time performance. This invention offers a simple and convenient process. It achieves protocol lightweighting by simplifying the DTLS handshake process and adapting to lightweight encryption algorithms. A dynamic "link-key" binding mechanism associates the DTLS session key with the PLC / RF link status, preventing handshake re-handshakes during link switching. Forward error correction and integrity verification ensure secure data transmission. This invention reduces handshake messages by 40%, computational cost by 35%, and link switching latency to ≤50ms. It supports IPv6 and DL / T645 power protocols, meeting the secure communication needs of terminals such as low-voltage distribution meters and photovoltaic inverters. It is also compatible with the Elec-Tech operating system, improving the reliability and security of dual-mode link transmission.

[0069] Obviously, the embodiments described above are merely preferred embodiments of the present invention, and not all embodiments. The accompanying drawings illustrate preferred embodiments of the present invention, but do not limit the scope of the patent. The present invention can be implemented in many different forms; rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing specific embodiments, or make equivalent substitutions for some of the technical features. Any equivalent structures made using the content of this specification and drawings, directly or indirectly applied to other related technical fields, are similarly within the scope of patent protection of this invention.

Claims

1. A lightweight DTLS protocol optimization method, characterized in that, Includes the following steps: S1. Merge the ClientHello and KeyExchange messages of the DTLS handshake into a single frame message, omitting redundant extended fields and retaining only the encryption suite negotiation and session ID fields required by the power terminal; S2. Lightweight encryption combination is selected to replace the traditional RSA+AES combination; S3. A terminal identity pre-authentication mechanism is introduced. After the power terminal is authenticated for the first time, the validity period of the stored session ticket is extended to 24 hours. When accessing again, the session key can be reused directly without having to go through the complete handshake process again.

2. The lightweight DTLS protocol optimization method according to claim 1, characterized in that, The encryption combination in S2 is SM4 symmetric encryption + SM2 asymmetric encryption + SM3 hash algorithm.

3. A dual-mode link secure transmission method based on the lightweight DTLS protocol optimization method described in claim 1 or 2, characterized in that, Includes the following steps: S10. The power terminal collects the SNR, bit error rate and connectivity parameters of the PLC / RF link in real time and generates a link health matrix. S20. Generate a master key based on the DTLS protocol, and derive a PLC-specific subkey and an RF-specific subkey based on the link health matrix to achieve dynamic binding between the key and the link; S30. The master node broadcasts a signaling message containing the network number and cipher suite through the optimized DTLS protocol; The slave node initiates a network access request based on the pre-stored identity certificate, and the master node allocates a dual-mode subkey after successful verification. S40: After the terminal data is encrypted with the corresponding link subkey, a message authentication code based on SM3 is attached, and it is transmitted in parallel via PLC / RF dual-mode. S50. When a link failure is detected, the terminal automatically switches to the backup link and generates a new link key through a subkey fast derivation algorithm without the need for a re-handshake.

4. The dual-mode link secure transmission method according to claim 3, characterized in that, In S10, the length of the simplified handshake message is ≤256 bytes, which is adapted to the resource limitations of the power terminal.

5. The dual-mode link secure transmission method according to claim 3, characterized in that, In S20, the parameters of the link health matrix include the SNR, bit error rate and link connectivity of the PLC / RF, and the parameter acquisition period is 100ms.

6. The dual-mode link secure transmission method according to claim 5, characterized in that, SNR threshold ≥ 60dB, bit error rate threshold ≤ 10 to the power of -5, and link connectivity is a binary identifier of 0 or 1.

7. The dual-mode link secure transmission method according to claim 3, characterized in that, In S50, the subkey fast generation algorithm is generated iteratively based on the master key and link ID through the SM3 hash algorithm, with a generation time of ≤10ms, and the subkey is dynamically updated according to the link status.

8. The dual-mode link secure transmission method according to claim 3, characterized in that, In step S40, forward error correction coding is introduced during data transmission. When the link error rate is ≤10 to the power of -3, automatic data error correction is achieved without retransmission.

9. A dual-mode link secure transmission method according to claim 3, characterized in that, The power terminal supports the IPv6 protocol stack and the DL / T645 power protocol. The optimized DTLS protocol is directly integrated into the secure communication component of the Elec-Tech operating system, and is compatible with the terminal's plug-and-play functionality.

10. A dual-mode link secure transmission method according to claim 3, characterized in that, In S50, the switching delay is ≤50ms.

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