Rail transit vehicle-ground security encryption control method and device based on national secret algorithm

Abstract

The invention provides a rail transit vehicle-ground security encryption control method based on a national cryptographic algorithm. The method comprises the following steps: realizing rail transit vehicle-ground security encryption control enabled by the national cryptographic algorithm by adopting a layered and segmented three-level security encryption architecture of a vehicle-mounted terminal layer-a network transmission layer-a core network layer; cooperative control of a national cryptographic algorithm is realized through three stages of terminal authentication, data encryption and tunnel encapsulation; in order to solve the problem of encryption interruption caused by wireless link switching such as 5G signal attenuation, the technical scheme of the patent realizes lossless switching through a three-layer linkage mechanism of signal monitoring, switching decision and key synchronization; self-adaptive intelligent adjustment of a key strategy is realized through a three-layer closed-loop architecture of environmental perception, intelligent evaluation and dynamic regulation and control; and the self-adaptive intelligent adjustment of the key strategy is realized through a three-layer closed-loop architecture of environmental perception, intelligent evaluation and dynamic regulation and control. And the national secret algorithm is combined with the block chain evidence storage technology to realize data tampering prevention, and the speed is high.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of rail transit train-ground safety encryption technology, in particular to a rail transit train-ground safety encryption control method and device of a national encryption algorithm. BACKGROUND

[0002] At present, the rail transit train-ground communication system mostly adopts an encryption scheme based on PKI (Public Key Infrastructure), which realizes device identity authentication and data encryption through certificate management. However, due to the characteristics of the train operation environment, such as distribution, strong mobility, limited computing resources of on-board devices, etc., the PKI system has problems such as complex certificate maintenance, high communication overhead, and difficulty in resisting quantum computing attacks. In addition, traditional wireless communication technologies such as injected WiFi and LTE have limitations in terms of anti-interference and spectrum efficiency, resulting in insufficient reliability and real-time performance of train-ground communication.

[0003] At the encryption technology level, the existing methods generally have the trade-off problem between key management complexity and security. Some systems use fixed encryption algorithms or a single key, which are vulnerable to replay attacks and man-in-the-middle attacks, and lack a dynamic update mechanism. Although some research attempts to introduce a certificateless public key system to simplify key management, the way of generating key pairs by terminals may cause security vulnerabilities due to device impersonation. In recent years, the introduction of national encryption algorithms (SM2 / SM3 / SM4) provides a new direction for self-controllable encryption schemes, which can fully support national commercial encryption standards, and the SM4 segmented encryption reduces the computing load on the terminal side, and the SM2 / SM3 combination resists quantum computing attacks and man-in-the-middle tampering, which can adapt to on-board embedded devices and support seamless compatibility of multi-level clearing systems across cities. SUMMARY

[0004] The present application aims to overcome the deficiencies of traditional PKI systems, such as reliance on certificate storage and inadequate quantum encryption adaptability, to provide a self-controllable, high real-time, and national encryption standard-compliant security communication support for smart rail transit.

[0005] To achieve the above-mentioned application purpose, the present application provides a rail transit train-ground safety encryption control method of a national encryption algorithm, comprising:

[0006] A three-level security encryption architecture of "on-board terminal layer-network transmission layer-core network layer" is adopted to realize the rail transit train-ground safety encryption control enabled by the national encryption algorithm;

[0007] The national encryption algorithm is cooperatively controlled through three stages of "terminal authentication-data encryption-tunnel encapsulation";

[0008] In view of the problem of encryption interruption caused by wireless link switching such as 5G signal attenuation, the present patent technology scheme realizes lossless switching through a three-layer linkage mechanism of "signal monitoring-switching decision-key synchronization";

[0009] The adaptive intelligent adjustment of the key strategy is realized through the three-layer closed-loop architecture of "environment perception-intelligent evaluation-dynamic regulation".

[0010] The adaptive intelligent adjustment of the key strategy is realized through the three-layer closed-loop architecture of "environment perception-intelligent evaluation-dynamic regulation".

[0011] Further, the layered and segmented three-level security encryption architecture of "vehicle terminal layer-network transmission layer-core network layer" realizes the track traffic vehicle-ground security encryption control enabled by the national secret algorithm, specifically including:

[0012] In the vehicle terminal layer, the embedded national secret security module integrated with the SM3 hardware acceleration chip can generate SM3 hash digest with business type label for the original business data in real time, and write the label information into the special field of the data packet header, and synchronize the microsecond-level timestamp to ensure the data timeliness. The SM4 encryption module implements differential processing according to the business label type: for 1024 bytes / block of video stream data, a block encryption strategy is adopted, and an SM3 hash value is embedded at the end of each block of ciphertext to form a composite data packet structure of "ciphertext+hash";

[0013] The multi-mode radio frequency unit supports WiFi6, 5G, and LTE three-channel parallel transmission to the transmission layer;

[0014] In the data transmission stage, the frequency division multiplexing controller realizes dynamic allocation of frequency band resources by analyzing the SM3 label of the data packet, and the key synchronization protocol module receives the SM4 key update instruction encrypted by SM2 from the ground control center, decrypts the new key and distributes it to the vehicle terminal, and the switching delay is controlled within 50ms;

[0015] In the core network layer, the SM2 national secret gateway receives the data packet of the transmission layer, and performs a cross-domain three-level authentication mechanism: first, decrypt the SM2 encrypted device identity information, compare the pre-stored public key fingerprint whitelist, and improve the illegal terminal interception rate; second, extract the SM3 hash value and business label of the data packet to implement classified forwarding, and the hash value of the key data such as video stream and ticket information is written into the blockchain node simultaneously; The blockchain architecture adopts a three-node distributed deployment of the subway company, the clearing center, and the regulatory agency, and realizes block generation time within 2s based on the Raft consensus algorithm, and the light node only synchronizes the block header information; Finally, the built-in clearing rule smart contract automatically triggers a five-level response mechanism when it detects SM3 verification failure or instruction timestamp anomaly: freeze abnormal transactions, mark abnormal data packet source address, revoke device public key certificate and broadcast it to the whole network, start multi-link isolation mechanism, and prohibit the device to access 5G or LTE special network frequency band and force it to downgrade to ordinary channel.

[0016] Further, the three stages of "terminal authentication-data encryption-tunnel encapsulation" realize the collaborative control of the national secret algorithm, including:

[0017] In the terminal authentication phase, a two-way authentication mechanism based on the SM2 elliptic curve algorithm is established: the vehicle-mounted terminal carries a pre-set SM2 public key and the SM2 private key held by the ground server for key negotiation, and a 256-bit SM4 session key is dynamically derived after the exchange of session parameters; the key life cycle is managed in real time by the ground server, and the authentication process time delay is controlled within 100 ms through an optimized algorithm to balance the authentication efficiency and security;

[0018] In the data encryption phase, a business data-aware block encryption strategy is implemented: first, data classification processing is performed, and SM4-CBC mode encryption is used for low-latency business such as train status data and control instructions, which are segmented into 1024 bytes / block fixed block length, and video stream data is encrypted using SM4-CTR mode after segmentation; then, using the encryption module coordination mechanism, CBC mode guarantees the strong integrity of control instructions through chain dependency between data blocks, and CTR mode supports parallel encryption to meet the real-time requirements of video stream; then, the hash verification system performs SM3 hash operation on each block of ciphertext to generate a 256-bit digest value, and the hash value is attached to the tail of the ciphertext to form a "ciphertext + hash" composite data packet; finally, after the composite data packet is encapsulated by the GRE tunnel protocol, the tunnel parameters are configured to the vehicle-mounted terminal by SM2 encryption, and the tunnel payload is encrypted twice using SM4-CTR, constructing IPsec-level end-to-end security protection;

[0019] In the core network processing layer, after stripping the GRE tunnel header, the multi-mode decryption mechanism selects the decryption mode according to the business type, and SM4-CBC serial decryption is used for control instructions and SM4-CTR parallel decryption is used for video stream; the double verification system recalculates the SM3 hash value of the decrypted plaintext and compares it with the attached hash value of the data packet, and if they do not match, it is determined to be tampered with, and the blockchain evidence alarm is triggered in an abnormal situation; the blockchain evidence and audit linkage mechanism writes the SM3 hash value that passes the verification into the three-node architecture distributed blockchain nodes of the subway company, clearing center and regulatory agency, and the light node only synchronizes the block header information; when tampering is detected, the smart contract automatically executes the five-level response mechanism of freezing the data source address, notifying the SM2 authentication center to revoke the device permission, etc., to realize full-link security control.

[0020] Further, the "signal monitoring-switching decision-key synchronization" three-layer linkage mechanism realizes lossless switching, which includes:

[0021] In the vehicle-mounted terminal monitoring area, a multi-standard signal monitoring instrument group is integrated, and real-time 5G, WiFi6, and LTE link parameters are monitored; when the 5G signal strength ≤-90dBm or the packet loss rate exceeds 5%, the switching decision module is triggered, and the switching instruction is sent to the network control point;

[0022] At the wireless link layer, the frequency division multiplexing controller divides the frequency band through a band-pass filter to achieve physical isolation and establish a dynamic priority strategy: control instructions force the priority use of LTE low-latency channels, video streams are secondarily allocated 5G high-frequency bands, and ordinary data packets are directed to WiFi6 frequency bands; when 5G signals deteriorate, service migration is performed: original 5G services are switched to WiFi6 frequency bands, data packet service tags are synchronously updated, and a key update request is initiated to the ground control layer;

[0023] At the ground control layer, the ground control center key generation module generates an SM4 session key bound to the device ID in real time after receiving the switching instruction, effectively preventing replay attacks; the new key is encrypted by the SM2 algorithm and broadcast to the vehicle terminal through the LTE private network channel; the vehicle safety chip performs SM2 decryption to obtain the new key, buffers service data during switching, and resumes transmission immediately after the key update is completed; the SM3 hash chain technology is used to ensure switching continuity: the last packet hash value is sent to the ground control center through the LTE link before switching, and the first packet hash value needs to be verified for validity after switching, otherwise the automatic retransmission mechanism is triggered.

[0024] Further, the "environment perception-intelligent evaluation-dynamic regulation" three-layer closed-loop architecture realizes adaptive intelligent adjustment of key strategies, including:

[0025] At the input layer, a multi-source parameter acquisition module is integrated to obtain three types of key environmental indicators in real time: 5G\WiFi6\LTE signal attenuation values output by the atomic vehicle signal receiver, base station load rates monitored by the core network flow probe, and attack feature codes output by the intrusion detection system (IDS); then, through a time window alignment mechanism, asynchronous data is synchronized to construct a multi-dimensional time sequence feature matrix containing signal strength, network load, and security events, and the Min-Max normalization method is used to eliminate dimensional differences;

[0026] At the LSTM neural network structure layer, a double-layer LSTM neural network model is constructed: first, the input gate receives the current time environmental parameters and the previous time hidden state; second, the memory unit captures the time correlation of signal attenuation and the spatial correlation of load fluctuation through the cell state update mechanism, establishing a nonlinear mapping relationship between passenger flow congestion and base station signal jitter; finally, the attention mechanism is used in the output gate to amplify the key feature weight, generating a dynamic security threshold;

[0027] In the output layer, a three-level risk assessment matrix is established: when the security threshold is greater than 0.8, it is a low-risk state, representing a stable operation scene in the suburb, at this time, SM4-128 bit simplified encryption is used to reduce the calculation load; when the security threshold is between 0.5 and 0.8, it is a medium-risk state, representing a slow driving scene in the station, at this time, SM4-128 bit encryption is maintained to enhance the LTE link protection; when the security threshold is less than 0.5, it is a high-risk state, representing a scene that the train is disturbed and attacked in the tunnel, at this time, SM4-256 bit strong encryption is used, and WiFi6\5G\LTE three-link redundant transmission is activated synchronously.

[0028] Further, the "data encryption-on-chain evidence-smart audit" three-level linkage constructs a trusted cross-domain security system, which includes:

[0029] In the data source and encryption area, the original data module collects rail transit business data such as train status and ticket records, extracts key fields, and then performs encryption processing using SM4-CTR mode, the encryption key is dynamically generated through the SM2 key negotiation mechanism of the vehicle terminal and the ground server, and the encrypted data is transmitted through a special APN channel to ensure that the business plaintext is not exposed to the public network environment throughout the process; then, a 256-bit SM3 hash digest is generated for the original data before encryption, a microsecond timestamp is added, and a data source digital signature based on an SM2 private key is added to form a complete evidence chain;

[0030] In the blockchain processing area, a three-node alliance chain architecture of the subway operator, the clearing center and the regulatory agency is constructed, and the functions of each node are defined: the operator node verifies the authenticity of the local business data hash, the clearing center node performs cross-domain transaction clearing calculation, and the regulatory agency node audits the compliance of the whole chain operation; then, the SM3 hash value is synchronized across nodes through the Raft consensus algorithm, packaged as structured transaction data and written into a new block, the light node adopts a block header synchronization strategy, and the transaction existence is quickly verified through the MerklePatricia Tree (MPT) to balance the storage efficiency and security;

[0031] In the audit execution area, an intelligent contract automatic audit is deployed, when real-time monitoring hash verification fails and the timestamp is abnormal, a five-level response mechanism is triggered immediately: freezing abnormal transactions, sending device revocation instructions to the SM2 authentication center, adding the public key of the involved device to the certificate revocation list (CRL) and broadcasting it to the whole network, starting a multi-link isolation mechanism to prohibit abnormal devices from accessing the 5G and LTE private network, and forcibly downgrading to the WiFi6 public channel to ensure the availability of basic communication.

[0032] The application provides a device for the above-mentioned rail transit vehicle-ground security encryption control method of national secret algorithm, which comprises a vehicle terminal layer, a network transmission layer and a core network layer,

[0033] At the vehicle terminal layer, an embedded national secret security module integrating an SM3 hardware acceleration chip is used to generate an SM3 hash digest with a service type label for original service data in real time, and write the label information into a 4-byte special field in the data packet header, and a microsecond-level timestamp is synchronously added to ensure data timeliness; an SM4 encryption module is used to implement differential processing according to the service label type,

[0034] Multi-mode radio frequency units are used to support WiFi6, 5G and LTE three channels to send to the transmission layer, wherein: the WiFi6 base station is used to receive ordinary data packets, and the 5.8GHz frequency band is isolated through a frequency division multiplexing band pass filter to avoid interference with the 5G and LTE frequency bands; the 5G base station is used for special video stream transmission, relying on the millimeter wave large bandwidth characteristics to guarantee a transmission rate of greater than 1Gbps, and a built-in signal strength monitoring module reports the wireless signal strength attenuation state to the ground control center in real time; the LTE base station is used to preferentially guarantee low-latency control instruction transmission, and provides a special transmission channel for critical instructions such as emergency braking;

[0035] At the network transmission layer, a frequency division multiplexing (FDM) controller is used to realize dynamic allocation of frequency band resources by analyzing the SM3 label of the data packet, and when the 5G signal strength attenuation or the packet loss rate exceeds 5%, the 5G service is automatically migrated to the WiFi6 frequency band and the packet header label is updated; a key synchronization protocol module receives the SM4 key update instruction encrypted by SM2 from the ground control center, decrypts the new key and distributes it to the vehicle terminal after decryption;

[0036] At the core network layer, an SM2 national secret gateway receives the data packet of the transmission layer, and is used to perform a cross-domain three-level authentication mechanism: first, the SM2 encrypted device identity information is decrypted, and the pre-stored public key fingerprint whitelist is compared to improve the interception rate of illegal terminals; second, the SM3 hash value and the service label of the data packet are extracted for classified forwarding, and the hash value of critical data such as video stream and ticket information is written into a blockchain node at the same time; finally, a built-in clearing rule smart contract is used, and when SM3 verification fails or the instruction timestamp is abnormal, a five-level response mechanism is automatically triggered: freezing abnormal transactions, marking the source address of abnormal data packets, revoking the device public key certificate and broadcasting it to the whole network, starting a multi-link isolation mechanism, and prohibiting the device from accessing the 5G or LTE special network frequency band and forcing it to be downgraded to a normal channel.

[0037] Compared with the traditional vehicle-ground communication encryption technology, the present application has the following obvious advantages:

[0038] 1. The national secret algorithm (SM2 / SM3 / SM4) is used to replace the traditional PKI system, the SM2 anti-quantum feature and the SM4 dynamic key mechanism are used to resist man-in-the-middle attacks and quantum computing threats, and the blockchain storage technology is used to realize data tamper-proofing, and the security is improved by more than 3 times compared with the RSA / AES scheme.

[0039] 2. The layered and segmented encryption architecture (such as SM4-CBC / CTR mode) reduces the end-side computing load by 50%, the SM3 hardware acceleration chip makes the hash calculation speed reach 1Gbps, and the encryption time delay is less than 5ms; the multi-link redundancy and SM4 key synchronization protocol guarantee that the switching delay is less than 50ms, and the communication reliability (MTBF) breaks through 100,000 hours.

[0040] 3. The AI-driven key management strategy supports a flexible update period of 1-60 seconds, combines with the LSTM network to realize real-time environmental risk perception, dynamically adjusts the encryption strength, solves the rigidity problem of the traditional fixed key mechanism, and improves the resource utilization rate by 40%.

[0041] 4. Fully adapt to domestic cryptographic standards (GM / T series), eliminate dependence on foreign algorithms; realize "data available and invisible" through SM4 encryption + blockchain digest, meet the cross-domain clearing privacy compliance requirements.

[0042] The scheme overcomes the industry pain points such as complex certificate management and weak anti-interference ability, and provides high-security, low-latency and self-controllable communication guarantee for smart rail transit. BRIEF DESCRIPTION OF DRAWINGS

[0043] Figure 1 It is a rail transit train-ground safety encryption control system architecture diagram of a national cryptographic algorithm.

[0044] Figure 2 It is a layered and segmented encryption flowchart.

[0045] Figure 3 It is a multi-link switching and key synchronization schematic diagram.

[0046] Figure 4 It is an AI dynamic key management logic diagram.

[0047] Figure 5 It is a blockchain audit and privacy protection schematic diagram. DETAILED DESCRIPTION

[0048] In order to better understand the purpose, structure and function of the present application, the present application of a national cryptographic algorithm rail transit train-ground safety encryption control method and device will be further described in detail below in combination with the drawings.

[0049] As shown in the accompanying Figure 1 As shown in the accompanying

[0050] (1) In the vehicle terminal layer, the embedded national secret security module integrated with the SM3 hardware acceleration chip can generate SM3 hash digest with service type label for the original service data in real time, write the label information into the special field of the data packet header, and synchronize the microsecond-level timestamp to ensure the data timeliness. The SM4 encryption module implements differential processing according to the service label type: for 1024 bytes / block of video stream data, a block encryption strategy is adopted, and SM3 hash value is embedded at the end of each block of ciphertext to form a composite data packet structure of "ciphertext+hash".

[0051] The multi-mode radio frequency unit supports WiFi6, 5G and LTE three channels to send to the transmission layer in parallel, wherein: the WiFi6 base station receives ordinary data packets, and realizes 5.8GHz frequency band isolation through frequency division multiplexing band-pass filter to avoid interference with 5G and LTE frequency bands; the 5G base station is dedicated for video stream transmission, relying on the characteristics of millimeter wave large bandwidth to guarantee ≥1Gbps transmission rate, and the built-in signal strength monitoring module reports the wireless signal strength attenuation state to the ground control center in real time; the LTE base station preferentially guarantees low latency control instruction transmission, and provides a dedicated transmission channel for critical instructions such as emergency braking.

[0052] The SM2 two-way authentication mechanism is executed before data transmission, and the initial SM4 session key is established after the base station identity is verified based on the preset root certificate.

[0053] (2) In the data transmission stage, the frequency division multiplexing (FDM) controller realizes dynamic allocation of frequency band resources by analyzing the SM3 label of the data packet, and when detecting 5G signal strength attenuation, automatically migrates 5G service to WiFi6 frequency band and updates the packet header label. The key synchronization protocol module receives the SM4 key update instruction encrypted by SM2 from the ground control center, decrypts the new key after decryption, and distributes it to the vehicle terminal, and the switching delay control is within 50ms. The switching process verifies the data packet sequence continuity through SM3 hash chain, effectively preventing packet loss and retransmission attack.

[0054] (3) In the core network layer, the SM2 national secret gateway receives the transport layer data packet, and performs a three-level cross-domain authentication mechanism: first, decrypt the SM2 encrypted device identity information, compare the pre-stored public key fingerprint whitelist, and improve the illegal terminal interception rate; second, extract the data packet SM3 hash value and service label to implement classified forwarding, and the hash value of key data such as video stream and ticket information is written into the blockchain node at the same time. The blockchain architecture adopts a three-node distributed deployment of the subway company, clearing center and regulatory agency. Based on the Raft consensus algorithm, the block generation time is within 2s, and the light node only synchronizes the block header information. Finally, the built-in clearing rule smart contract automatically triggers a five-level response mechanism when it detects SM3 verification failure or instruction timestamp anomaly: freeze abnormal transactions, mark abnormal data packet source address, revoke device public key certificate and broadcast it to the whole network, start multi-link isolation mechanism, and prohibit the device from accessing 5G or LTE private network frequency and force it to downgrade to ordinary channel.

[0055] As shown in the accompanying Figure 2 The technical scheme of the present patent realizes the coordinated control of the national secret algorithm through the three stages of "terminal authentication-data encryption-tunnel encapsulation", and the specific technical scheme is implemented as follows:

[0056] (1) In the terminal authentication stage, a bidirectional authentication mechanism based on the SM2 elliptic curve algorithm is established: the vehicle-mounted terminal carries a pre-installed SM2 public key and the SM2 private key held by the ground server for key negotiation, and after completing the exchange of session parameters, a 256-bit SM4 session key is dynamically derived. The key life cycle is managed in real time by the ground server, and the authentication process time is controlled within 100ms through an optimized algorithm to ensure the balance between authentication efficiency and security.

[0057] (2) In the data encryption stage, a business data-aware block encryption strategy is implemented: first, data classification processing is performed, and SM4-CBC mode encryption is used for low-latency business such as train status data and control instructions, which are divided into 1024 bytes / block fixed block length, and video stream data is encrypted after being divided into blocks using SM4-CTR mode; then, using the encryption module coordination mechanism, CBC mode guarantees the strong integrity of control instructions through chain dependence between data blocks, and CTR mode supports parallel encryption to meet the real-time requirements of video stream; then, the hash verification system performs SM3 hash operation on each block of ciphertext to generate a 256-bit digest value, which is attached to the tail of the ciphertext to form a "ciphertext + hash" composite data packet; finally, the tunnel encapsulation is performed on the composite data packet after GRE tunnel protocol encapsulation, the tunnel parameters are configured to the vehicle-mounted terminal through SM2 encryption, the tunnel load is encrypted twice using SM4-CTR, and IPsec level end-to-end security protection is constructed.

[0058] (3) In the core network processing layer, the multi-mode decryption mechanism selects the decryption mode according to the service type after stripping the GRE tunnel header, the control instruction uses SM4-CBC serial decryption, and the video stream implements SM4-CTR parallel decryption. The double-checking system recalculates the SM3 hash value of the decrypted plaintext and compares it with the attached hash value of the data packet. If they do not match, it is determined to be tampered with, and the blockchain storage alarm is triggered in the event of an anomaly. The blockchain storage and audit linkage mechanism writes the SM3 hash value that passes the verification into the three-node architecture distributed blockchain nodes of the subway company, clearing center and regulatory agency. The light node only synchronizes the block header information. When tampering is detected, the smart contract automatically executes the five-level response mechanism of freezing the data source address, notifying the SM2 authentication center to revoke device permissions, etc., to realize full-link security control.

[0059] As shown in the accompanying Figure 3 For the problem of encryption interruption caused by wireless link switching such as 5G signal attenuation, the patent technical solution realizes lossless switching through the "signal monitoring-switching decision-key synchronization" three-layer linkage mechanism. The specific technical implementation is as follows:

[0060] (1) In the vehicle terminal monitoring area, integrate a multi-standard signal monitoring instrument group to monitor the real-time 5G (3.5GHz frequency band), WiFi6 (5.8GHz frequency band), and LTE (1.8GHz frequency band) link parameters. When the 5G signal strength is ≤-90dBm or the packet loss rate exceeds 5%, trigger the switching decision module and send a switching instruction to the network control point. Typical monitoring scenario example: 5G signal strength is -95dBm, which is lower than the threshold -90dBm, and it is in a signal interruption state; WiFi6 signal strength is -70dBm, which is in a signal stable state; LTE signal strength is -80dBm, which is in a signal available state.

[0061] (2) At the wireless link layer, the frequency division multiplexing controller divides the frequency band through a band-pass filter to achieve physical isolation and establishes a dynamic priority policy: control instructions are forced to use LTE low-latency channels first, video streams are secondarily allocated to 5G high-frequency bands, and ordinary data packets are directed to WiFi6 frequency bands. When the 5G signal deteriorates, perform service migration: switch the original 5G service to the WiFi6 frequency band, synchronize the data packet service tag, and initiate a key update request to the ground control layer.

[0062] (3) In the ground control layer, the ground control center key generation module generates an SM4 session key bound to the device ID immediately after receiving the switching instruction, effectively preventing replay attacks. The new key is encrypted by the SM2 algorithm and broadcast to the vehicle terminal through the LTE private network channel. The vehicle safety chip executes SM2 decryption to obtain the new key, buffers service data during the switching period, and resumes transmission immediately after the key update is completed. The SM3 hash chain technology is used to ensure switching continuity: the last packet hash value is sent to the ground control center through the LTE link before switching, and the first packet hash value needs to be verified for effectiveness after switching, otherwise the automatic retransmission mechanism is triggered.

[0063] Attached Figure 4 As shown in the figure, the patent technical solution realizes adaptive intelligent adjustment of key strategy through a three-layer closed-loop architecture of "environment perception-intelligent evaluation-dynamic regulation", and the specific technical implementation is as follows:

[0064] (1) In the input layer, a multi-source parameter acquisition module is integrated to obtain three types of key environmental indicators in real time: 5G\WiFi6\LTE signal attenuation values output by the atomic vehicle signal receiver, base station load rate monitored by the core network traffic probe, and attack feature code output by the intrusion detection system (IDS). Then, through the time window alignment mechanism, asynchronous data synchronization is realized, a multi-dimensional time sequence feature matrix containing signal strength, network load, and security events is constructed, and the Min-Max normalization method is used to eliminate dimensional differences.

[0065] (2) In the LSTM neural network structure layer, a double-layer LSTM neural network model is constructed: first, the input gate receives the current time environmental parameters and the previous time hidden state; second, the memory unit captures the time correlation of signal attenuation and the spatial correlation of load fluctuation through the cell state update mechanism, establishes a nonlinear mapping relationship between passenger flow congestion and base station signal jitter; finally, the attention mechanism is used in the output gate to amplify the key feature weight, and a dynamic security threshold is generated.

[0066] (3) In the output layer, a three-level risk assessment matrix is established: when the security threshold is greater than 0.8, it is a low-risk state, representing a stable operation scenario in the suburbs, at which time SM4-128 simplified encryption is used to reduce computational load; when the security threshold is between 0.5 and 0.8, it is a medium-risk state, representing a slow-moving scenario in the station, at which time SM4-128 encryption is maintained to enhance LTE link protection; when the security threshold is less than 0.5, it is a high-risk state, representing a scenario where the train is attacked and disturbed while driving in the tunnel, at which time SM4-256 strong encryption is used, and WiFi6\5G\LTE three-link redundancy transmission is activated simultaneously.

[0067] The above strategy execution engine automatically switches the encryption algorithm strength and adjusts the link redundancy strategy according to the real-time risk level, achieving dynamic balance between security and efficiency.

[0068] As shown in the accompanying Figure 5 The patent technology scheme builds a trusted cross-domain security system through the three-level linkage of "data encryption - on-chain evidence - intelligent audit", and the specific technical implementation is as follows:

[0069] (1) In the data source and encryption area, the original data module collects rail transit business data such as train status and ticket record, extracts key fields, and uses SM4-CTR mode for encryption processing. The encryption key is dynamically generated through the SM2 key negotiation mechanism of the vehicle terminal and the ground server. The encrypted data is transmitted through a special APN channel to ensure that the business plaintext is not exposed to the public network environment throughout the process. Then, a 256-bit SM3 hash digest is generated for the original data before encryption, with a microsecond timestamp and a data source digital signature based on the SM2 private key, forming a complete evidence chain.

[0070] (2) In the blockchain processing area, a three-node alliance chain architecture of subway operators, clearing centers and regulatory agencies is constructed, and the functions of each node are defined: the operator node verifies the authenticity of local business data hash, the clearing center node performs cross-domain transaction clearing calculation, and the regulatory agency node audits the compliance of the whole chain operation. Then, the SM3 hash value is synchronized across nodes through the Raft consensus algorithm, packaged as structured transaction data and written into a new block. The light node uses a block header synchronization strategy to quickly verify the existence of transactions through the Merkle Patricia Tree (MPT), ensuring the balance between storage efficiency and security.

[0071] (3) In the audit execution area, an intelligent contract automatic audit is deployed. When real-time monitoring of hash verification fails and the timestamp is abnormal, a five-level response mechanism is triggered immediately: freeze abnormal transactions, send device revocation instructions to the SM2 authentication center, add the public key of the involved device to the certificate revocation list (CRL) and broadcast it to the whole network, start a multi-link isolation mechanism to prevent abnormal devices from accessing 5G and LTE private networks, and force them to downgrade to WiFi6 public channels to ensure basic communication availability.

[0072] The above process realizes the security management and traceable audit of rail transit data throughout its life cycle through the deep integration of cryptography, distributed consensus and smart contracts.

Claims

1. A method for encrypted control of rail transit vehicle-to-ground security using a national cryptographic algorithm, characterized in that, include: A layered and segmented three-level security encryption architecture consisting of "vehicle terminal layer - network transmission layer - core network layer" is adopted to realize the security encryption control of rail transit vehicles and ground enabled by national cryptographic algorithms; The collaborative control of national cryptographic algorithms is achieved through three stages: "terminal authentication - data encryption - tunnel encapsulation". To address the issue of encryption interruption caused by wireless link switching due to 5G signal attenuation, this patented technical solution achieves lossless switching through a three-layer linkage mechanism of "signal monitoring - switching decision - key synchronization"; The key strategy is adaptively and intelligently adjusted through a three-layer closed-loop architecture of "environmental perception - intelligent evaluation - dynamic control". A trusted cross-domain security system is built through a three-level linkage of "data encryption - on-chain evidence storage - intelligent auditing".

2. The method for encrypted control of rail transit vehicle-to-ground security using a national cryptographic algorithm according to claim 1, characterized in that: The layered and segmented three-level security encryption architecture of "vehicle terminal layer - network transmission layer - core network layer" enables vehicle-to-ground security encryption control of rail transit powered by national cryptographic algorithms, specifically including: At the vehicle terminal layer, an embedded national cryptographic security module integrating an SM3 hardware acceleration chip can generate SM3 hash digests with service type tags in real time from raw business data, and write the tag information into a dedicated field in the data packet header, while simultaneously attaching a microsecond-level timestamp to ensure data timeliness; the SM4 encryption module performs differentiated processing based on the service tag type: for video streams of 1024 bytes / block... The data uses a block encryption strategy, embedding an SM3 hash value at the end of each ciphertext block to form a composite data packet structure of "ciphertext + hash". The multi-standard radio frequency unit supports parallel transmission of WiFi 6, 5G, and LTE signals to the transport layer via three channels; During the data transmission phase, the frequency division multiplexing controller dynamically allocates frequency band resources by parsing the SM3 tag of the data packet. The key synchronization protocol module receives the SM4 key update instruction encrypted by SM2 from the ground control center, decrypts it, and distributes the new key to the vehicle terminal. The switching latency is controlled within 50ms. At the core network layer, the SM2 national cryptographic gateway receives transport layer data packets and executes a cross-domain three-level authentication mechanism: First, it decrypts the SM2 encrypted device identity information and compares it with the pre-stored public key fingerprint whitelist to improve the interception rate of illegal terminals; second, it extracts the SM3 hash value and business tag of the data packet for classified forwarding, and writes the hash values ​​of key data such as video streams and ticketing information to the blockchain node simultaneously; the blockchain architecture adopts a three-node distributed deployment of the subway company, clearing center, and regulatory agency, and achieves block generation time within 2 seconds based on the Raft consensus algorithm, with light nodes only synchronizing block header information; finally, a built-in clearing rule smart contract automatically triggers a five-level response mechanism when an SM3 verification failure or an abnormal instruction timestamp is detected: freezing abnormal transactions, marking the source address of abnormal data packets, revoking the device's public key certificate and broadcasting it across the network, starting a multi-link isolation mechanism, prohibiting the device from accessing 5G or LTE private network frequency bands and forcibly downgrading it to a normal channel.

3. The method for encrypted control of rail transit vehicle-to-ground security using a national cryptographic algorithm according to claim 1, characterized in that, The three stages of "terminal authentication - data encryption - tunnel encapsulation" to achieve collaborative control of national cryptographic algorithms include: During the terminal authentication phase, a two-way authentication mechanism based on the SM2 elliptic curve algorithm is established: the vehicle terminal carries a pre-set SM2 public key and negotiates the key with the SM2 private key held by the ground server. After completing the exchange of session parameters, a 256-bit SM4 session key is dynamically derived. The key lifecycle is managed in real time by the ground server. The authentication process latency is controlled within 100ms through optimization algorithms to ensure a balance between authentication efficiency and security. During the data encryption phase, a business data-aware block encryption strategy is implemented: First, data is classified and processed. Low-latency services such as train status data and control commands are encrypted using SM4-CBC mode, divided into fixed block lengths of 1024 bytes / block. Video stream data is encrypted using SM4-CTR mode after being divided into blocks. Next, the encryption module collaboration mechanism is utilized. CBC mode ensures strong integrity of control commands through chain dependency between data blocks, while CTR mode supports parallel encryption to meet the real-time requirements of video streams. Subsequently, the hash verification system performs SM3 hash operation on each ciphertext block to generate a 256-bit digest value, which is appended to the end of the ciphertext to form a "ciphertext + hash" composite data packet. Finally, tunnel encapsulation is performed by encapsulating the composite data packet using the GRE tunneling protocol. Tunnel parameters are configured to the on-board terminal using SM2 encryption, and the tunnel payload uses SM4-CTR secondary encryption to build IPsec-level end-to-end security protection. At the core network processing layer, after stripping the GRE tunnel header, the multi-mode decryption mechanism selects the decryption mode according to the service type. Control commands are decrypted serially using SM4-CBC, while video streams are decrypted in parallel using SM4-CTR. A dual verification system recalculates the SM3 hash value of the decrypted plaintext and compares it with the hash value appended to the data packet. If a mismatch is found, tampering is determined, and a blockchain evidence alarm is triggered in case of an anomaly. The blockchain evidence storage and audit linkage mechanism writes the verified SM3 hash value into a three-node distributed blockchain node architecture involving the subway company, clearing center, and regulatory agency. Light nodes only synchronize block header information. When a tampering event is detected, the smart contract automatically executes a five-level response mechanism, including freezing the data source address and notifying the SM2 certification center to revoke device permissions, to achieve full-link security control.

4. The method for encrypted control of rail transit vehicle-to-ground security using a national cryptographic algorithm according to claim 1, characterized in that, The three-layer linkage mechanism of "signal monitoring - handover decision - key synchronization" enables lossless handover, including: In the vehicle terminal monitoring area, a multi-mode signal monitoring instrument group is integrated to update 5G, WiFi6, and LTE link parameters in real time. When the 5G signal strength is detected to be ≤-90dBm or the packet loss rate exceeds 5%, the handover decision module is triggered to send a handover command to the network control point. At the radio link layer, the frequency division multiplexing controller achieves physical isolation by dividing frequency bands through bandpass filters and establishes a dynamic priority strategy: control commands force the priority use of LTE low-latency channels, video streams are secondarily allocated to 5G high-frequency bands, and ordinary data packets are directed to the WiFi 6 band; when the 5G signal deteriorates, service migration is performed: the original 5G services are switched to the WiFi 6 band, the data packet service labels are updated synchronously, and a key update request is sent to the ground control layer. At the ground control layer, after receiving the handover command, the key generation module of the ground control center immediately generates an SM4 session key bound to the device ID, effectively preventing replay attacks. The new key is encrypted using the SM2 algorithm and broadcast to the vehicle terminal through the LTE private network channel. The vehicle security chip performs SM2 decryption to obtain the new key, caches service data during the handover, and resumes transmission immediately after the key is updated. The SM3 hash chain technology is used to ensure handover continuity: before the handover, the hash value of the last packet is sent to the ground control center through the LTE link. After the handover, the hash value of the first packet must pass the validity check; otherwise, an automatic retransmission mechanism is triggered.

5. The method for encrypted control of rail transit vehicle-to-ground security using a national cryptographic algorithm according to claim 1, characterized in that, The aforementioned three-layer closed-loop architecture of "environmental perception-intelligent assessment-dynamic control" enables adaptive and intelligent adjustment of the key strategy, including: The input layer integrates a multi-source parameter acquisition module to acquire three key environmental indicators in real time: 5G / WiFi6 / LTE signal attenuation values ​​output by the atomic vehicle-mounted signal receiver, base station load rate monitored by the core network traffic probe, and attack signature codes output by the intrusion detection system (IDS). Then, asynchronous data synchronization is achieved through a time window alignment mechanism to construct a multi-dimensional time-series feature matrix containing signal strength, network load, and security events, and the Min-Max normalization method is used to eliminate dimensional differences. In the LSTM neural network structure layer, a two-layer LSTM neural network model is constructed: First, the input gate receives the environmental parameters at the current time and the hidden state at the previous time; second, the memory unit captures the temporal correlation of signal attenuation and the spatial correlation of load fluctuation through the cell state update mechanism, and establishes a nonlinear mapping relationship between passenger flow congestion and base station signal jitter; finally, the output gate uses an attention mechanism to amplify the weights of key features and generate a dynamic safety threshold. At the output layer, a three-level risk assessment matrix is ​​established: when the security threshold is >0.8, it is a low-risk state, representing a stable operation scenario in suburban areas. In this case, SM4-128-bit simplified encryption is used to reduce the computational load; when the security threshold is between 0.5 and 0.8, it is a medium-risk state, representing a slow-moving scenario within a station. In this case, SM4-128-bit encryption is maintained to enhance LTE link protection; when the security threshold is <0.5, it is a high-risk state, representing a scenario where the train is subjected to interference and attacks while traveling in a tunnel. In this case, SM4-256-bit strong encryption is used, and redundant transmission of WiFi6, 5G, and LTE links is activated simultaneously.

6. The method for encrypted control of rail transit vehicle-to-ground security using a national cryptographic algorithm according to claim 1, characterized in that, The aforementioned three-tiered linkage of "data encryption - on-chain evidence storage - intelligent auditing" constructs a trusted cross-domain security system, including: In the data source and encryption area, the raw data module collects rail transit business data such as train status and ticketing records. After extracting key fields, it encrypts the data using the SM4-CTR mode. The encryption key is dynamically generated through the SM2 key negotiation mechanism between the on-board terminal and the ground server. The encrypted data is transmitted through a dedicated APN channel to ensure that the plaintext of the business is never exposed to the public network environment. Then, a 256-bit SM3 hash digest is generated from the raw data before encryption, and a microsecond-level timestamp and a digital signature of the data source based on the SM2 private key are added to form a complete chain of evidence. In the blockchain processing area, a three-node consortium blockchain architecture is constructed, comprising the subway operator, the clearing center, and the regulatory agency. The functions of each node are clearly defined: the operator node verifies the authenticity of local business data hashes, the clearing center node performs cross-domain transaction clearing calculations, and the regulatory agency node audits the compliance of the entire chain operation. Subsequently, the SM3 hash value is synchronized across nodes using the Raft consensus algorithm, packaged into structured transaction data, and written into a new block. Light nodes adopt a block header synchronization strategy and use Merkle PatriciaTree (MPT) to quickly verify the existence of transactions, ensuring a balance between storage efficiency and security. Deploy automated auditing of smart contracts in the audit execution area. When real-time monitoring shows hash verification failures and timestamp anomalies, immediately trigger a five-level response mechanism: freeze abnormal transactions, send a device revocation command to the SM2 certification center, add the public key of the device involved to the Certificate Revocation List (CRL) and broadcast it across the entire network, activate a multi-link isolation mechanism, prohibit abnormal devices from accessing 5G and LTE private networks, and force downgrade to WiFi 6 public channels to ensure the availability of basic communication.

7. An apparatus for a rail transit vehicle-to-ground security encryption control method based on a national cryptographic algorithm as described in claim 1, characterized in that, Including the vehicle terminal layer, network transmission layer, and core network layer. At the vehicle terminal layer, an embedded national cryptographic security module integrating an SM3 hardware acceleration chip is used to generate SM3 hash digests with business type tags in real time from the raw business data, and write the tag information into a 4-byte dedicated field in the header of the data packet, and simultaneously attach a microsecond-level timestamp to ensure data timeliness; the SM4 encryption module is used to implement differentiated processing according to the business tag type; The multi-standard radio frequency unit supports parallel transmission of WiFi 6, 5G, and LTE signals to the transport layer. Specifically: the WiFi 6 base station receives ordinary data packets and uses a frequency division multiplexing bandpass filter to isolate the 5.8GHz band, avoiding interference with the 5G and LTE bands; the 5G base station is used for dedicated video stream transmission, leveraging the high bandwidth of millimeter waves to ensure a transmission rate of ≥1Gbps, and has a built-in signal strength monitoring module to report the wireless signal strength attenuation status to the ground control center in real time; the LTE base station prioritizes the transmission of low-latency control commands and provides a dedicated transmission channel for critical commands such as emergency braking. At the network transport layer, the frequency division multiplexing (FDM) controller is used to dynamically allocate frequency band resources by parsing the SM3 tag of the data packet. When the 5G signal strength attenuation or packet loss rate exceeds 5%, it automatically migrates the 5G service to the WiFi 6 frequency band and updates the packet header tag. The key synchronization protocol module receives the SM4 key update instruction encrypted by SM2 from the ground control center, decrypts it, and distributes the new key to the vehicle terminal. At the core network layer, the SM2 national cryptographic gateway receives transport layer data packets and uses them to execute a cross-domain three-level authentication mechanism: First, it decrypts the SM2 encrypted device identity information and compares it with a pre-stored public key fingerprint whitelist to improve the interception rate of illegal terminals; second, it extracts the SM3 hash value and service tag of the data packet for classified forwarding, and writes the hash values ​​of key data such as video streams and ticketing information to the blockchain node simultaneously; finally, it has a built-in clearing rule smart contract, which automatically triggers a five-level response mechanism when it detects SM3 verification failure or abnormal instruction timestamp: freezing abnormal transactions, marking the source address of abnormal data packets, revoking the device's public key certificate and broadcasting it across the network, starting a multi-link isolation mechanism, prohibiting the device from accessing 5G or LTE private network frequency bands and forcibly downgrading it to a normal channel.

Images