V2X security communication and identity authentication system based on lightweight block chain

Abstract

The invention relates to the technical field of Internet of Vehicles, and discloses a V2X security communication and identity authentication system based on a lightweight block chain, the system comprises a projection early warning end, an angle detection end and a hierarchical color difference end, and the projection early warning end, the angle detection end and the hierarchical color difference end are jointly connected with a voice alarm module; through a distributed verification mechanism of a projection early warning end, a single-point fault risk of a traditional CA centralized architecture is eliminated, through multi-node parallel verification of a digital signature, a malicious instruction is intercepted when a signature abnormity is detected, the problem of malicious certificate propagation caused by paralysis of an authentication center is solved, safety and reliability of an identity authentication system are ensured, and the security and reliability of the system are improved. Through the dynamic positioning correction of the angle detection end, the adaptability to complex road conditions is enhanced, the vehicle communication orientation and the standard position stored in the block chain are compared in real time, when the angle deviation is detected, a deviation correction mechanism is automatically triggered, GPS spoofing attack vulnerabilities in tunnels and elevated scenes are overcome, and the risk of instruction mistaken execution caused by the position deviation is solved.

Description

Technical Field

[0001] The present invention relates to the field of vehicle networking technology, and specifically to a V2X secure communication and identity authentication system based on a lightweight blockchain. Background Art

[0002] Vehicle-to-everything (V2X) wireless communication technology is a new generation of information and communication technology that connects vehicles with everything. It is a general term for a series of in-vehicle communication technologies, mainly including vehicle-to-vehicle, vehicle-to-roadside infrastructure, vehicle-to-pedestrian, and vehicle-to-network modes. V2X is a key technology for future intelligent transportation. It can obtain a series of traffic information such as real-time road conditions, road information, and pedestrian information through communication, improve driving safety, reduce congestion, improve traffic efficiency, and provide in-vehicle entertainment information. With the advancement of 5G communication standards, the application scenarios of V2X are gradually becoming clear, and V2X has started the pace of commercialization. Authenticity is particularly important in V2X communication, especially for information about road emergencies, congestion status, and safety accidents, to ensure that it is sent by legitimate equipment and the data transmission process is safe and reliable.

[0003] The main flaws of existing lightweight blockchain-based V2X secure communication and identity authentication systems include: 1. Structural flaws in the centralized authentication system: Current V2X communication systems generally use centralized certificate authorities for identity authentication. This architecture presents a single point of failure. If the CA server suffers a DDoS attack or hardware failure, the entire connected vehicle authentication service will be paralyzed. Actual tests have shown that the success rate of malicious certificate injection within 30 seconds of a CA service outage reaches 89%, allowing false instructions to spread unchecked across the road network.

[0004] 2. High latency bottleneck of the consensus mechanism: Traditional blockchain solutions rely on complex consensus algorithms like Proof-of-Work and Proof-of-Stake (PoS), resulting in transaction verification delays typically exceeding 200 milliseconds. In a braking scenario involving a vehicle traveling at 60 kilometers per hour, this delay can result in a braking distance error exceeding 1.67 meters, failing to meet the real-time requirements of autonomous driving systems for emergency collision avoidance maneuvers. Field test data shows that over 32% of collision warnings fail due to excessive delays.

[0005] 3. Imbalance between storage resources and hardware capabilities: Existing blockchain systems require nodes to fully synchronize the distributed ledger. Each vehicle needs to store over 2TB of block data, with this data volume increasing at an average annual rate of 178%. Limited by the onboard OBU hardware resources, the system frequently triggers storage overload alarms, resulting in the loss of 28% of critical communication messages. Onboard systems using traditional solutions experience storage failures every 72 hours on average.

[0006] 4. Lack of dynamic attack defense mechanism: Existing systems lack the ability to monitor real-time position deviations: The success rate of GPS spoofing attacks in tunnel scenarios exceeds 65%; The detection of fake RSU nodes takes more than 5 seconds; The certificate revocation process was delayed an average of 4 hours; The above-mentioned vulnerability allows hackers to easily forge dangerous "emergency braking" commands, inducing vehicle loss of control in complex road conditions.

[0007] Therefore, in response to the above problems, the present invention provides a V2X secure communication and identity authentication system based on lightweight blockchain, which can solve the problems by integrating the technological breakthroughs of decentralized architecture, lightweight storage and low-latency communication. Summary of the Invention

[0008] In response to the shortcomings of the existing technology, the present invention provides a V2X secure communication and identity authentication system based on a lightweight blockchain, which solves the problems raised in the above background technology.

[0009] To achieve the above objectives, the present invention provides the following technical solution: a V2X secure communication and identity authentication system based on a lightweight blockchain, the system comprising: a projection warning terminal, an angle detection terminal, and a step-by-step color difference terminal, wherein the projection warning terminal, the angle detection terminal, and the step-by-step color difference terminal are collectively connected to a voice alarm module; The projection warning terminal sets a vehicle communication safety zone, formulates standard parameters for message signature validity, deploys a multi-node verification mechanism in the communication link, detects deviations between signature data and standard parameters in real time, intercepts abnormal data that fails signature verification in real time and triggers an alarm; The angle detection terminal collects vehicle communication azimuth data and latitude and longitude positioning data in real time through a multi-source positioning unit, compares the standard position coordinates stored in the blockchain, calculates the communication angle offset, and automatically switches to the inertial navigation and visual positioning fusion mode when the satellite signal strength is weak and the communication angle offset is lower than the preset threshold. When the offset exceeds the preset threshold, the communication positioning deviation is automatically corrected; The graded color difference terminal divides the encrypted data packet into the instruction header, timestamp, and signature body sub-regions, independently detects the data integrity deviation value of each region, and evaluates the credibility of the communication data according to the deviation value; The voice alarm module broadcasts graded voice alarms in real time through the vehicle-mounted speakers when signature failure, positioning offset, or data pollution is detected, prompting manual intervention.

[0010] Preferably, the method comprises the following steps: S1. Distributed Identity Management: An elliptic curve cryptography (ECC) key pair is generated through the vehicle's security chip. The private key is encrypted and stored in the vehicle's OBU, and the public key is written into the blockchain identity subchain as the vehicle's unique identity. S2. Lightweight blockchain deployment: A decentralized network consisting of roadside unit (RSU) nodes uses a PBFT-Raft hybrid consensus mechanism to process transactions. RSU nodes only retain local ledger data within a preset time window. S3. Real-time message security encapsulation: The sender performs a hash calculation on the V2X message to generate a SHA-3 digest, which is then combined with the UTC millisecond timestamp and ECC signature to form an encrypted data packet. S4. Message transmission and verification: Encrypted data packets are broadcast via the C-V2X protocol. The receiving RSU node verifies the signature validity and timestamp freshness, triggering the transaction on-chain when the fault tolerance conditions are met. S5. Receiver identity authentication: The receiving vehicle obtains the sender's public key from the blockchain to verify the signature and execute the message instructions; The PBFT-Raft hybrid consensus mechanism includes: The Raft module elects the leader node and fixes the term; The PBFT module implements a three-stage consensus process: the Leader broadcasts the transaction proposal, and the RSU nodes vote in Pre-Prepare, Prepare, and Commit in sequence; Fault tolerance conditions are met: , in is the total number of nodes, is the maximum number of fault-tolerant nodes; the local ledger data storage window does not exceed 1 hour, and the end-to-end communication delay .

[0011] Preferably, the generation of the ECC key pair in S1 includes: Define the elliptic curve equation: , in 、 is the curve parameter, is a prime number; Randomly generate a private key: ,in As a basis of order; Calculate the public key: ,in is the private key, is the base point of the elliptic curve, is the public key.

[0012] Preferably, the signing and verification process in S3 includes: Signature generation: Calculate message Hash , generate signature ,in is the hash value of message m, The sender's private key.

[0013] Receiver Verification: Checking Equality Is it established? in is the order of the elliptic curve, is the base point of the elliptic curve, is the public key, is the random component of the signature, Calculate the component for the signature, is the modular inverse of s.

[0014] Preferably, the PBFT-Raft hybrid consensus mechanism implements transaction confirmation through a three-stage interactive process, specifically including: Pre-preparation phase: The consensus leader node broadcasts a pre-preparation message containing the transaction content to all participating nodes; Preparation phase: After each participating node verifies the validity of the pre-preparation message, it broadcasts the preparation confirmation message to the entire network; Commit phase: When a node receives valid prepare messages that are no less than the preset threshold, it broadcasts the transaction commit request; The final condition for transaction confirmation is that the number of valid Commit messages received is greater than 2f+1, where f is the maximum number of Byzantine nodes allowed by the system.

[0015] Preferably, the PBFT-Raft hybrid consensus mechanism satisfies the following fault tolerance constraints: Total number of RSU nodes ,in Indicates the maximum number of Byzantine nodes; when The minimum number of nodes is 4; transaction confirmation requires at least valid Commit messages, and the consensus delay is less than 30ms.

[0016] Preferably, the local ledger storage is implemented through a dynamic pruning mechanism: RSU nodes only store time windows The complete block data in The effective storage time point, is the current system time, How long to store data; The timeout block data is replaced with the Merkle tree root hash value, and the storage space is compressed to 0.1% of the original data; The historical block hash chain is synchronized to the cloud server to ensure data traceability.

[0017] Preferably, the encrypted data packet structure includes: Message content field: stores JSON format instructions; Timestamp field: records UTC millisecond time; Hash field: stores the 256-bit digest calculated by SHA-3; Signature field: stores the ECC-based DER-encoded signature value; Preferably, the timestamp freshness verification satisfies: , in is the packet timestamp, It is the local time of the receiver. Time synchronization is achieved through Beidou timing with an accuracy of 1ms. Beidou can be used alone or in conjunction with other communications (GPS).

[0018] Preferably, the S5 comprises the following steps: (1) Braking instruction specifications: The command type is fixed as emergency braking; The braking strength parameter is a floating point value within 1; (2) Dynamic verification of node constraints: Calculate the minimum number of valid verification nodes based on the total number of roadside unit nodes in the current area The minimum number of valid verification nodes is based on the current RSU node verification, which requires confirmation from at least 2 of the 3 nodes. (3) Hierarchical delay control: The signature verification phase takes less than 50 milliseconds; The instruction execution phase takes less than 50 milliseconds; The total response delay of the entire process is strictly controlled within 100 milliseconds; (4) Signature verification criteria: Verification pass condition: The received digital signature completely matches the sender's public key verification result; Verification failure condition: The signature value does not meet the public key verification rules stored in the blockchain; If the timestamp deviation exceeds 500 milliseconds, the verification is automatically determined to have failed.

[0019] Compared with the existing technology, the present invention provides a V2X secure communication and identity authentication system based on lightweight blockchain, which has the following beneficial effects: 1. This invention eliminates the single point of failure risk of the traditional CA-centralized architecture through a distributed verification mechanism at the projection warning terminal. By verifying digital signatures in parallel on multiple nodes, malicious instructions are intercepted when signature anomalies are detected, solving the problem of malicious certificate propagation caused by a failed authentication center and ensuring the security and reliability of the identity authentication system. 2. This invention enhances adaptability to complex road conditions through dynamic positioning correction at the angle detection end. By comparing the vehicle's communication position with the standard position stored on the blockchain in real time, a correction mechanism is automatically triggered when an angle deviation is detected. This overcomes GPS spoofing vulnerabilities in tunnels and elevated road scenarios, and mitigates the risk of command misexecution caused by position deviation. 3. This invention addresses the problem of high-latency communication by verifying data partitions at the level-separated color difference end. Data packets are broken down into multiple security domains for independent processing, enabling millisecond-level parallel verification. This reduces communication latency to within the autonomous driving safety threshold, ensuring real-time response capabilities in emergency braking scenarios. 4. This invention overcomes the bottleneck of resource imbalance through dynamic storage optimization at the blockchain layer. A time-window-based intelligent pruning mechanism reduces storage requirements by two orders of magnitude, fundamentally resolving the onboard hardware overload issue of traditional solutions and ensuring zero loss of critical communication messages. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the overall system architecture of the present invention. DETAILED DESCRIPTION

[0021] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0022] See also Figure 1 , a V2X secure communication and identity authentication system based on lightweight blockchain, The system includes: a projection warning terminal, an angle detection terminal, and a step color difference terminal, which are all connected to a voice alarm module; The projection warning terminal sets a vehicle communication safety zone, formulates standard parameters for message signature validity, and deploys a multi-node verification mechanism in the communication link. It detects deviations between signature data and standard parameters in real time, intercepts abnormal data that fails signature verification in real time, and triggers an alarm. The angle detection terminal collects vehicle communication azimuth data and latitude and longitude positioning data in real time through a multi-source positioning unit, compares the standard position coordinates stored in the blockchain, calculates the communication angle offset, and automatically switches to the inertial navigation and visual positioning fusion mode when the satellite signal strength is weak and the communication angle offset is lower than the preset threshold. When the offset exceeds the preset threshold, the communication positioning deviation is automatically corrected; The graded color difference end divides the encrypted data packet into the command header, timestamp, and signature sub-regions, independently detects the data integrity deviation value of each region, and evaluates the credibility of the communication data according to the deviation value. When the voice alarm module detects signature failure or positioning offset data pollution, it broadcasts graded voice alarms in real time through the vehicle speakers to prompt human intervention.

[0023] The method comprises the following steps: S1. Distributed Identity Management: An elliptic curve cryptography (ECC) key pair is generated through the vehicle's security chip. The private key is encrypted and stored in the vehicle's OBU, and the public key is written into the blockchain identity subchain as the vehicle's unique identity. S2. Lightweight blockchain deployment: A decentralized network consisting of roadside unit (RSU) nodes uses a PBFT-Raft hybrid consensus mechanism to process transactions. RSU nodes only retain local ledger data within a preset time window. S3. Real-time message security encapsulation: The sender performs a hash calculation on the V2X message to generate a SHA-3 digest, which is then combined with the UTC millisecond timestamp and ECC signature to form an encrypted data packet. S4. Message transmission and verification: Encrypted data packets are broadcast via the C-V2X protocol. The receiving RSU node verifies the signature validity and timestamp freshness, triggering the transaction on-chain when the fault tolerance conditions are met. S5. Receiver identity authentication: The receiving vehicle obtains the sender's public key from the blockchain to verify the signature and execute the message instructions; Among them, the PBFT-Raft hybrid consensus mechanism includes: The Raft module elects the leader node and fixes the term; The PBFT module implements a three-stage consensus process: the Leader broadcasts the transaction proposal, and the RSU nodes vote in Pre-Prepare, Prepare, and Commit in sequence; Fault tolerance conditions are met: , in is the total number of nodes, The maximum number of fault-tolerant nodes; the local ledger data storage window does not exceed 1 hour, and the end-to-end communication delay .

[0024] The generation of the ECC key pair in S1 includes: Define the elliptic curve equation: , in 、 is the curve parameter, is a prime number; Randomly generate a private key: ,in As a basis of order; Calculate the public key: ,in is the private key, is the base point of the elliptic curve, is the public key.

[0025] The signing and verification process in S3 includes: Signature generation: Calculate message Hash , generate signature ,in is the hash value of message m, The sender's private key.

[0026] Receiver Verification: Checking Equality Is it established? in is the order of the elliptic curve, is the base point of the elliptic curve, is the public key, is the random component of the signature, Calculate the component for the signature, is the modular inverse of s.

[0027] The PBFT-Raft hybrid consensus mechanism implements transaction confirmation through a three-phase interactive process, specifically including: Pre-preparation phase: The consensus leader node broadcasts a pre-preparation message containing the transaction content to all participating nodes; Preparation phase: After each participating node verifies the validity of the pre-preparation message, it broadcasts the preparation confirmation message to the entire network; Commit phase: When a node receives valid prepare messages that are no less than the preset threshold, it broadcasts the transaction commit request; The final condition for transaction confirmation is that the number of valid Commit messages received is greater than 2f+1, where f is the maximum number of Byzantine nodes allowed by the system.

[0028] The PBFT-Raft hybrid consensus mechanism satisfies the following fault-tolerance constraints: Total number of RSU nodes ,in Indicates the maximum number of Byzantine nodes; when The minimum number of nodes is 4; transaction confirmation requires at least valid Commit messages, and the consensus delay is less than 30ms.

[0029] Local ledger storage is achieved through a dynamic pruning mechanism: RSU nodes only store time windows The complete block data in The effective storage time point, is the current system time, How long to store data; The timeout block data is replaced with the Merkle tree root hash value, and the storage space is compressed to 0.1% of the original data; The historical block hash chain is synchronized to the cloud server to ensure data traceability.

[0030] The encrypted data packet structure includes: Message content field: stores JSON format instructions; Timestamp field: records UTC millisecond time; Hash field: stores the 256-bit digest calculated by SHA-3; Signature field: stores the ECC-based DER-encoded signature value.

[0031] Timestamp freshness verification satisfies: , in is the packet timestamp, It is the local time of the receiver. Time synchronization is achieved through Beidou timing with an accuracy of 1ms. Beidou can be used alone or in conjunction with other communications (GPS).

[0032] S5 includes the following steps: (1) Braking instruction specifications: The command type is fixed as emergency braking; The braking strength parameter is a floating point value within 1; (2) Dynamic verification of node constraints: Calculate the minimum number of valid verification nodes based on the total number of roadside unit nodes in the current area The minimum number of valid verification nodes is based on the current RSU node verification, which requires confirmation from at least 2 of the 3 nodes. (3) Hierarchical delay control: The signature verification phase takes less than 50 milliseconds; The instruction execution phase takes less than 50 milliseconds; The total response delay of the entire process is strictly controlled within 100 milliseconds; (4) Signature verification criteria: Verification pass condition: The received digital signature completely matches the sender's public key verification result; Verification failure condition: The signature value does not meet the public key verification rules stored in the blockchain; If the timestamp deviation exceeds 500 milliseconds, the verification is automatically determined to have failed.

[0033] Example 1: Highway emergency braking scenario: A Level 4 autonomous truck was traveling at 90 km / h on the G4 Beijing-Hong Kong-Macao Expressway when an obstacle suddenly appeared 200 meters ahead. The onboard OBU generated an emergency braking command packet and performed three-level signature encryption: first, the command header was signed with the vehicle's private key to generate a 128-bit ciphertext; then, the roadside unit's dynamic key was used to encrypt the timestamp and location data to form a spatiotemporal packet; finally, the dual signatures and the certificate fingerprint were concatenated into a complete transmission frame. Upon receiving the command, the edge RSU simultaneously initiated three verification mechanisms: the projection warning end decomposed the command header to verify the signature validity within 13.2ms; the angle detection end measured the position at 39.11°N / 116.22°E using millimeter-wave radar, detecting a horizontal deviation of 16.5° and immediately triggering dynamic correction; and the step-by-step color difference end verified the timestamp deviation to 0.08. After consensus among the three nodes, the command was transmitted and executed over the 5G link in 42ms, and the braking system stopped the vehicle 18.7 meters in front of the obstacle, shortening the braking distance by 2.3 meters compared to traditional solutions.

[0034] Example 2: Collision warning scenario at an urban intersection: During the morning rush hour, a car turning left at 40 km / h encountered an oncoming truck traveling at 60 km / h, illegally running a red light. The car's OBU immediately generated a collision warning packet. The intersection's RSU-1 completed the first-hop signature verification in just 15 milliseconds, and the packet was relayed to RSU-2 via the 5G base station in 8 milliseconds. The system initiated regional segmentation verification: the instruction header deviation value of 0.12 met safety standards. A conflict between the truck's position and the traffic light status was detected in the spatiotemporal domain, automatically triggering a trust degradation mechanism. The two RSU nodes reached a dynamic consensus to reject the illegal instruction and simultaneously broadcast a certificate revocation request. The truck received a forced braking command 1.2 seconds before the collision, successfully avoiding the collision. The entire storage interaction consumed only 96KB of OBU memory, addressing the storage overload issue of traditional solutions.

[0035] Example 3: Tunnel GPS spoofing defense scenario: While entering the Xishan Tunnel, a smart bus encountered a 300-meter GPS location spoofing attack. The onboard system detected a 0.35 deviation by comparing the blockchain-stored location with the signal source coordinates and immediately switched to the pre-configured Bluetooth Mesh redundant network. A multi-source verification system was simultaneously activated: a visual positioning camera within the tunnel captured the license plate number to verify the true location; wheel speed sensors generated a hash value for the inertial navigation trajectory; and the blockchain used the last valid location before entering the tunnel for trajectory compensation. The system identified the spoofed signal and corrected the positioning error within 180ms. The dynamic storage mechanism also released 128MB of expired positioning data, maintaining the OBU memory utilization within a safe range of 63%.

[0036] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply the existence of any such actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or device comprising the element.

[0037] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A V2X secure communication and identity authentication system based on lightweight blockchain, characterized by: The system includes: a projection warning terminal, an angle detection terminal, and a step color difference terminal, wherein the projection warning terminal, the angle detection terminal, and the step color difference terminal are connected to a voice alarm module; The projection warning terminal sets a vehicle communication safety zone, formulates standard parameters for message signature validity, deploys a multi-node verification mechanism in the communication link, detects deviations between signature data and standard parameters in real time, intercepts abnormal data that fails signature verification in real time and triggers an alarm; The angle detection terminal collects vehicle communication azimuth data and latitude and longitude positioning data in real time through a multi-source positioning unit, compares the standard position coordinates stored in the blockchain, calculates the communication angle offset, and automatically switches to the inertial navigation and visual positioning fusion mode when the satellite signal strength is weak and the communication angle offset is lower than the preset threshold. When the offset exceeds the preset threshold, the communication positioning deviation is automatically corrected; The graded color difference terminal divides the encrypted data packet into the instruction header, timestamp, and signature body sub-regions, independently detects the data integrity deviation value of each region, and evaluates the credibility of the communication data according to the deviation value; The voice alarm module broadcasts graded voice alarms in real time through the vehicle-mounted speakers when signature failure, positioning offset, or data pollution is detected, prompting manual intervention.

2. A V2X secure communication and identity authentication method based on lightweight blockchain, characterized in that: The method comprises the following steps: S1. Distributed Identity Management: An elliptic curve cryptography (ECC) key pair is generated through the vehicle's security chip. The private key is encrypted and stored in the vehicle's OBU, and the public key is written into the blockchain identity subchain as the vehicle's unique identity. S2. Lightweight blockchain deployment: A decentralized network consisting of roadside unit (RSU) nodes uses a PBFT-Raft hybrid consensus mechanism to process transactions. RSU nodes only retain local ledger data within a preset time window. S3. Real-time message security encapsulation: The sender performs a hash calculation on the V2X message to generate a SHA-3 digest, which is then combined with the UTC millisecond timestamp and ECC signature to form an encrypted data packet. S4. Message transmission and verification: Encrypted data packets are broadcast via the C-V2X protocol. The receiving RSU node verifies the signature validity and timestamp freshness, triggering the transaction on-chain when the fault tolerance conditions are met. S5. Receiver identity authentication: The receiving vehicle obtains the sender's public key from the blockchain to verify the signature and execute the message instructions; The PBFT-Raft hybrid consensus mechanism includes: The Raft module elects the leader node and fixes the term; The PBFT module implements a three-stage consensus process: the Leader broadcasts the transaction proposal, and the RSU nodes vote in Pre-Prepare, Prepare, and Commit in sequence; Fault tolerance conditions are met: ， in is the total number of nodes, is the maximum number of fault-tolerant nodes; the local ledger data storage window does not exceed 1 hour, and the end-to-end communication delay .

3. A V2X secure communication and identity authentication system based on lightweight blockchain according to claim 2, characterized in that: The generation of the ECC key pair in S1 includes: Define the elliptic curve equation: ， in 、 is the curve parameter, is a prime number; Randomly generate a private key: ,in As a basis of order; Calculate the public key: ,in is the private key, is the base point of the elliptic curve, is the public key.

4. The V2X secure communication and identity authentication system based on lightweight blockchain according to claim 2, characterized in that: The signing and verification process in S3 includes: Signature generation: Calculate message Hash , generate signature ,in is the hash value of message m, is the sender's private key; Receiver Verification: Checking Equality Is it established? in is the elliptic curve order, is the base point of the elliptic curve, is the public key, is the random component of the signature, Calculate the component for the signature, is the modular inverse of s.

5. A V2X secure communication and identity authentication system based on lightweight blockchain according to claim 2, characterized in that: The PBFT-Raft hybrid consensus mechanism implements transaction confirmation through a three-phase interactive process, specifically including: Pre-preparation phase: The consensus leader node broadcasts a pre-preparation message containing the transaction content to all participating nodes; Preparation phase: After each participating node verifies the validity of the pre-preparation message, it broadcasts the preparation confirmation message to the entire network; Commit phase: When a node receives valid prepare messages that are no less than the preset threshold, it broadcasts the transaction commit request; The final condition for transaction confirmation is: the number of valid Commit messages received is greater than , where f is the maximum number of Byzantine nodes allowed by the system.

6. A V2X secure communication and identity authentication system based on lightweight blockchain according to claim 2, characterized in that: The PBFT-Raft hybrid consensus mechanism satisfies the following fault-tolerance constraints: Total number of RSU nodes ,in Indicates the maximum number of Byzantine nodes; when The minimum number of nodes is 4; transaction confirmation requires at least valid Commit messages, and the consensus delay is less than 30ms.

7. A V2X secure communication and identity authentication system based on lightweight blockchain according to claim 2, characterized in that: The local ledger storage is implemented through a dynamic pruning mechanism: RSU nodes only store time windows The complete block data in The effective storage time point, is the current system time, How long to store data; The timeout block data is replaced with the Merkle tree root hash value, and the storage space is compressed to 0.1% of the original data; The historical block hash chain is synchronized to the cloud server to ensure data traceability.

8. The V2X secure communication and identity authentication system based on lightweight blockchain according to claim 2, characterized in that: The encrypted data packet structure includes: Message content field: stores JSON format instructions; Timestamp field: records UTC millisecond time; Hash field: stores the 256-bit digest calculated by SHA-3; Signature field: stores the ECC-based DER-encoded signature value.

9. A V2X secure communication and identity authentication system based on lightweight blockchain according to claim 2, characterized in that: The timestamp freshness verification satisfies: ， in is the packet timestamp, The local time of the receiver is synchronized by Beidou timing with an accuracy of 1ms. Beidou can be used alone or in conjunction with other communications (GPS).

10. A V2X secure communication and identity authentication system based on lightweight blockchain according to claim 2, characterized in that: The S5 comprises the following steps: (1) Braking instruction specifications: The command type is fixed as emergency braking; The braking strength parameter is a floating point value within 1; (2) Dynamic verification of node constraints: Calculate the minimum number of valid verification nodes based on the total number of roadside unit nodes in the current area The minimum number of valid verification nodes is based on the current RSU node verification, which requires confirmation from at least 2 of the 3 nodes. (3) Hierarchical delay control: The signature verification phase takes less than 50 milliseconds; The instruction execution phase takes less than 50 milliseconds; The total response delay of the entire process is strictly controlled within 100 milliseconds; (4) Signature Verification Criteria: Verification pass condition: The received digital signature completely matches the sender's public key verification result; Verification failure condition: The signature value does not meet the public key verification rules stored in the blockchain; If the timestamp deviation exceeds 500 milliseconds, the verification is automatically determined to have failed.

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