CN109996215A - A kind of multi-path communications method based on privacy sharing under vehicular ad hoc network network environment - Google Patents

Abstract

The invention is a multi-path communication method based on secret sharing under the vehicle-mounted ad hoc network environment. The Latin square matrix is used to find multiple disjoint paths between the starting node and the target node, and then the secret sharing is used to divide the symmetric encryption key into multiple sub-systems. key. At the same time, the encrypted message is also divided into multiple parts, and an equal amount of commitment is generated for each subkey to support fault tolerance, while the current timestamp is selected to resist replay attacks. The encrypted subkey, ciphertext, and commitment are jointly transmitted to the target node through various paths. The target node uses the subkey to reconstruct the key, and uses the key to decrypt the ciphertext to obtain the original message. This communication method greatly reduces the network load, improves the information transmission efficiency, and also has the characteristics of good stability, and it is not easy to be attacked or steal private data. This communication method also has high fault tolerance, and can provide normal services even when unstable factors such as network congestion, traffic restrictions, and node equipment damage occur.

Description

A multi-path communication method based on secret sharing in vehicle-mounted ad hoc network environment

technical field

The invention belongs to the technical field of robot communication, in particular to a multi-path communication method based on secret sharing in a vehicle-mounted ad hoc network environment.

Background technique

In recent years, the penetration rate of vehicles has increased significantly, resulting in a continuous increase in the number of vehicles on the road, and related problems such as road congestion, driving safety, and environmental pollution have become increasingly serious, which greatly affects people's normal travel. Therefore, there is a need for a new type of technology that enables vehicles to communicate with each other to provide safety and convenience for modern road traffic. Due to various demands, the Vehicular Ad-hoc Network (VANET for short) emerges as the times require. VANET is an ad-hoc multi-hop communication network composed of on-board nodes, road infrastructure and servers, providing intelligent traffic information services for drivers. In VANET, a vehicle driving on a road can be regarded as a mobile node, and a road infrastructure called a Road Side Unit (RSU) located beside the road can be regarded as a stationary node. Each vehicle is installed with an On Board Unit (OBU for short), which enables it to exchange information with the outside world. The communication mode in VANET can be divided into two parts: vehicle to vehicle (V2V for short) communication and vehicle to infrastructure (V2I for short). The V2V communication mode enables the vehicle to send the information data it has collected to other vehicles within the range, and can also act as a relay node to send the information received from the previous vehicle node to the next vehicle node. The information obtained by the vehicle is processed correspondingly through the processing equipment to provide drivers with safe and smooth driving conditions. The V2I communication mode realizes the transmission of information between the vehicle and the RSU, so that the information collected by the vehicle in a small area can be centralized with the RSU, and uploaded to the server through the RSU, so as to realize the analysis of road conditions and unified traffic management in the whole network.

However, in-vehicle ad hoc networks bring convenience to people, but they also face many challenges in terms of communication security and transmission efficiency. The information transmitted in VANET usually contains user-related private information. If the information is obtained by the attacker during the communication process, the user's privacy will be greatly violated. In the early VANET, the consideration of user privacy and security was not comprehensive, and it was difficult for private data to be well protected. In addition, the vehicle has a faster driving speed on the road, resulting in a shorter transfer time of information in VANET. Therefore, if the transmission efficiency problem cannot be effectively solved, the message will not be transmitted to the next node in time, which will affect the normal operation of the VANET. In response to the above problems, some experts and scholars have proposed corresponding solutions. Many existing schemes use digital signature technology to ensure the security of messages, and use symmetric encryption, batch authentication and other methods to improve communication efficiency. However, these schemes only transmit messages through one path, which cannot meet the real-time requirements, and the transmission process is still vulnerable to the attack and destruction of adversaries. In addition, the system has a low fault tolerance rate and cannot effectively resist the generation of unstable factors such as network congestion and equipment failure.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to provide a multi-path communication method based on secret sharing in a vehicle-mounted ad hoc network environment, which has the characteristics of high timeliness, resistance to attacks during information transmission and high fault tolerance.

In order to solve the above-mentioned technical problems, the technical scheme adopted in the present invention is:

A multi-path communication method based on secret sharing in a vehicle-mounted ad hoc network environment, which is characterized in that: using a Latin square matrix to find multiple disjoint paths between a starting node and a target node, and then using secret sharing to divide a symmetric encryption key into multiple A subkey; the encrypted message is also divided into multiple parts, and an equal amount of commitment is generated for each subkey to support fault tolerance; the encrypted subkey, ciphertext, and commitment are jointly transmitted to the target node through various paths; The target node uses the subkey to reconstruct the key, and uses the key to decrypt the ciphertext to obtain the original message. Specific steps are as follows:

Step 1, construct a Latin square matrix: construct a Latin square matrix based on the number of different elements in the logical transmission path;

Step 2, determine the transmission path: determine multiple disjoint transmission paths between the start node and the target node according to the Latin square matrix, the logical transmission path and the two dynamic operation sets;

Step 3, secret sharing initialization: use the RSA cryptographic algorithm to assign a set of public key pair and private key pair to each node; at the same time, select a non-zero random number for each path to mark the corresponding path;

Step 4, sub-key generation: select a univariate polynomial, and the constant term is the symmetric encryption key of the encrypted message; generate a sub-key for each path through this polynomial;

Step 5, secret sharing: After encrypting the original message using symmetric encryption, the ciphertext is also divided into multiple parts, each part corresponds to a path; a commitment is calculated for each subkey to support fault tolerance; To transmit data, use the public key of the target node to encrypt the sub-key, select the current timestamp to resist replay attacks, and use the cryptographic one-way hash function to ensure the validity of the transmitted data; The start node transmits to the target node;

Step 6, authentication: after receiving the data from each path, the target node first obtains the current timestamp, and verifies the validity of the timestamp in the received data according to the actual system requirements on the tolerance range limit; after the verification is successful, the target node Use its own private key to decrypt to obtain the sub-key, and verify the validity of the promise by checking the hash value; then, the target node uses the promise to judge the validity of the sub-key; if the sub-key is invalid, perform the error detection in step 7; If the subkey is valid, skip step 7;

Step 7, error detection: if the number of successfully verified subkeys does not meet the specified requirements, the target node will send an error report to the starting node; the starting node will verify the validity of the received error report and transmit it correctly. The data path returns information to the target node; the target node verifies the validity of the returned information. If the originating node does not return a message within the specified time or the number of failed verifications of the target node exceeds a certain value, the originating node is considered a malicious node and the communication with the originating node is terminated;

Step 8, key reconstruction: the target node reconstructs the symmetric key by using the valid sub-keys transmitted by the number of paths not less than the threshold value, and decrypts the ciphertext to obtain the original message.

Taking the 2-CN network as the communication model, the 2-CN network is modeled as an undirected graph G(n,±d ₁ ,±d ₂ ,...,±d _m ), where n is the number of nodes in the graph, are represented by 1, 2, ..., n respectively, and ±d ₁ to ±d _m represent the distance between each node and the adjacent 2m nodes in the undirected graph, respectively, and At this time, there are 2m shortest and node-disjoint paths, let LTP(S, E, SE) be the logical transmission path, representing the logical path from the starting node S to the target node E through the operation sequence SE, where the operation sequence SE={ d ₁ ,d ₂ ,...,d _j } is a subset of {±d ₁ ,±d ₂ ,...,±d _m }; based on the undirected graph G(n,±d ₁ ,±d ₂ ,...,±d _m ), each node has 2m adjacent nodes, in order to find the disjoint path of 2m nodes, the first set of operations is FO={±d ₁ ,±d ₂ , ...,±d _m }, the set of last operations is LO.

The specific steps of constructing the Latin square matrix in the said step 1 are as follows: constructing the Latin square matrix based on the number of different elements in SE, let FO=LO={±d ₁ ,±d ₂ ,...,±d _m }, The number of different elements in SE is, firstly take d ₁ , d ₂ ,..., d _j' as the first row element of the Latin square matrix, and the subsequent j'-1 rows are all based on the previous row, and put the elements in the previous row The first element of is moved to the end, and the other elements are moved forward one place in sequence, and finally a j'×j' Latin square matrix is formed.

The specific steps of determining the transmission path in the said step 2 are as follows: insert the remaining j-j' elements in SE into the middle of each row in the Latin square matrix to obtain j' node disjoint paths, and remove the FO and LO with SE. the same element;

For the set FO that contains pairs of forward and reverse operations d' and -d', randomly select a P _i from the existing j' paths, 0<i≤j', and add the two operations to the original There are two new paths d'||{P _i }||-d' and -d'||{P _i }||d', and remove d in FO and LO ' and -d'; since the forward and reverse operations performed simultaneously on any node in the graph G(n,±d ₁ ,±d ₂ ,...,±d _m ) can cancel each other out, the correct get new path;

For the remaining single operations in FO Add it to the front and back of the original operation at the same time; in order to ensure that the path can reach the target node E, it is necessary to reverse the two operations added to the middle of the operation, i.e.

the described operation Merge based on {±d ₁ , ±d ₂ ,...,±d _m } to guarantee minimization, if The subsets in {d ₁ ,d ₂ ,...,d _b } satisfy d ₁ +d ₂ +...+d _b =d _c , then replace { _{d 1} ,d ₂ ,... ,d _b } makes the constructed path the shortest, so as to obtain a new path and removed in FO and LO

The specific steps of the secret sharing initialization in the described step 3 are as follows: select two large prime numbers p and q, select a prime order cyclic group G, and g is a generator in the group G;

Before node deployment, each node is assigned a public key (PK _i ,n) and a private key (SK _i ,n) using the RSA cryptographic algorithm, where i is the node subscript, n is the product of p and q, and PK _i is relatively prime to (p-1)(q-1), PK _i SK _i =1mod(p-1)(q-1);

Randomly select 2m non-zero elements r ₁ , r ₂ ,...,r _2m from the finite field GF(p) as the common information of the 2m paths.

The specific steps of the sub-key generation in the said step 4 are as follows: construct a t-1 order unary polynomial f(x)=a ₀ +a ₁ x+a ₂ x ² +...+a _t-1 x ^{t -1} , where a ₁ , a ₂ ,...,a _t-1 is a random non-zero integer in GF(p), a ₀ is a symmetric key k; the starting node S generates 2m sub-keys for 2m paths The key k _i is used to share the symmetric key k and the message M with the target node E. The calculation method of k _i is as follows:

The specific steps of the secret sharing in the described step 5 are as follows: use the key k to symmetrically encrypt the message M, and divide the ciphertext into 2m parts, namely M ₁ , M ₂ , . . . , M _2m ;

Calculate a commitment _wi for each subkey, i=1,2,...,2m; _wi is calculated as follows:

When transmitting the symmetric key k and message M from the starting node S to the target node E through the open channel, the security and authenticity of the transmitted information need to be protected. The specific process is as follows:

S1, use the public key PK _e of the target node E to encrypt the subkey _ki ;

S2, in order to resist replay attacks, select the current timestamp T;

S3, use the cryptographic one-way hash function h(·) to calculate h(k _i , w _i , T) to ensure the validity of the transmitted information;

S4, transmit information through 2m paths

The specific steps of the authentication in the said step 6 are as follows: after receiving the information from each path, the target node E obtains the current timestamp T', and proves that the received timestamp is valid by verifying |T'-T|<T _exp , where T _exp is the expected delay time;

E is calculated using the private key SK _i And by verifying that the equation h(k′ _i , _wi , T) = h( _ki , _wi , T) is established to prove that the commitment _wi is valid;

E judges the validity of the sub-key _ki in the path _Pi by the verification formula, and the verification formula is as follows:

If the above formula holds, the sub-key _ki is valid, that is, _ki can be used to reconstruct the symmetric key k, otherwise _ki cannot be used for reconstruction, and the error detection in step 7 is performed.

The specific steps of error detection in the above-mentioned step 7 are as follows: when S and E communicate, due to the use of (t, 2m) secret sharing, if there are t or more paths, the verification formula (3) can be established, E can reconstruct a valid symmetric key, and after obtaining the symmetric key, S and E can communicate through encrypted messages;

If there are no t or more paths to verify (3), E sends an error report To S, after S successfully verifies the validity of the error report, it passes through a safe transmission information path that has established the verification formula (3), within the time T _exp Send to E; then, E checks the validity of _ki ; if S does not return within T _exp Or the number of verification failures exceeds a certain number, then S is regarded as a malicious node, and E terminates the communication with S.

The specific steps of the key reconstruction in the said step 8 are as follows: the target node E reconstructs the symmetric key through the sub-keys obtained in t or more paths, and the calculation method is as follows:

Subsequently, the message M can be obtained by decrypting the symmetric key k; if the number of subkeys is less than t, the message M cannot be recovered.

The beneficial effects that the multi-path communication method based on secret sharing can produce in the vehicle-mounted ad hoc network environment are as follows: the present invention constructs a parallel processing architecture for VANET communication by using the Latin square matrix, so that the information from the initial VANET equipment can be Parallel transfer to target VANET devices is possible. Compared with sequential processing, parallel processing greatly reduces network load, improves information transmission efficiency, avoids message lag, and meets the real-time requirements of VANET communication. In addition, by combining the parallel processing architecture with secret sharing, when the number of paths to correctly transmit information is not less than the threshold value, the target device can use the collected information to reconstruct the symmetric key and decrypt the ciphertext. In single-path communication, the system is vulnerable to various forms of attacks, and information security cannot be effectively guaranteed. In the present invention, if the number of paths destroyed by the attacker is less than the threshold value, any information called the key and the encrypted message cannot be obtained. At the same time, due to the characteristics of secret sharing, it can tolerate a certain number of paths that cannot successfully transmit information due to unstable factors such as network congestion, wandering restrictions or equipment failures, which reduces the failure rate of message transmission and ensures the robustness of VANET communication.

Description of drawings

FIG. 1 is a system structure model of VANET in a multi-path communication method based on secret sharing in a vehicle-mounted ad hoc network environment of the present invention.

FIG. 2 is a schematic diagram of an undirected graph G in a multi-path communication method based on secret sharing in a vehicle-mounted ad hoc network environment of the present invention.

FIG. 3 is a communication model of a multi-path communication method based on secret sharing in a vehicle-mounted ad hoc network environment of the present invention.

Detailed ways

The present invention will be further described below with reference to the accompanying drawings and specific preferred embodiments.

A secret sharing-based multi-path communication method in a vehicle-mounted ad hoc network environment is a secret-sharing-based multi-path communication scheme in a VANET environment.

In this embodiment, the 2-CN network is used as the communication model. The 2-CN network can be modeled as an undirected graph G(n, ±d ₁ , ±d ₂ ), where n is the number of nodes in the graph, represented by 1, 2,...,n, respectively, d ₁ and d ₂ determines the neighbors of each node, and Specifically, the neighboring nodes of node i are i±d ₁ (mod n) and i±d ₂ (mod n). The undirected graph used in this embodiment is G(n, ±d ₁ , ±d ₂ , . . . , ±d _m ), as shown in FIG. 2 , where It has been proved that from any starting node to the target node, there are 2m shortest and node-disjoint paths in this graph, which constitute the communication model of the present invention, as shown in FIG. 3 . Specifically, 2m pieces of secret information are first generated, and then the secret information is transmitted from the start node to the target node based on this communication model. In the graph G(n,±d ₁ ,±d ₂ ,...,±d _m ), let LTP(S,E,SE) be the logical transmission path, representing from the start node S to the target through the operation sequence SE A logical path for node E, where the sequence of operations SE={d ₁ ,d ₂ ,...,d _j } is a subset of {±d ₁ ,±d ₂ ,...,±d _m }. Based on the definition of the graph G(n,±d ₁ ,±d ₂ ,...,±d _m ), each node has 2m neighbors. To find 2m node disjoint paths, the set of first operations should be FO={±d ₁ ,±d ₂ ,...,±d _m }, and the set of last operations should be LO.

The specific steps of the multi-path communication method based on secret sharing in the vehicle ad hoc network environment are as follows:

Step 1, construct a Latin square matrix: construct a Latin square matrix based on the number of different elements in the logical transmission path.

In this embodiment, a Latin square matrix is constructed based on the number of different elements in SE: let FO=LO={±d ₁ , ±d ₂ , . . . , ±d _m }, and the number of different elements in SE is j′. First, take d ₁ , d ₂ ,...,d _j' as the first row element of the Latin square matrix, and the subsequent j'-1 rows are all based on the previous row, and move the first element in the previous row to the end, other The order of elements is shifted forward by one, and finally a j'×j' Latin square matrix is formed.

Step 2, determine the transmission path: determine a plurality of disjoint transmission paths between the start node and the target node according to the Latin square matrix, the logical transmission path and the two dynamic operation sets.

In this embodiment, the remaining jj' elements in SE are first inserted into the middle of each row in the Latin square matrix to obtain j' node disjoint paths, and elements in FO and LO that are the same as SE are removed. If the set FO contains pairs of forward and reverse operations, such as d' and -d', then randomly select a P _i from the existing j' paths, 0<i≤j', add the two operations Go to the front and back of the original operation, get two new paths d′||{P _i }||-d′ and -d′||{P _i }||d′, and in FO and LO Remove d' and -d'. Since the forward and reverse operations performed simultaneously on any node in the graph G(n,±d ₁ ,±d ₂ ,...,±d _m ) can cancel each other, the above process can correctly obtain the new path. Finally, for the remaining single operations in FO, e.g. Add it to the front and back of the original operation at the same time. In order to ensure that the path can reach the target node E, it is necessary to reverse the two operations added to the middle of the operation, i.e. In addition, operating Merging should be done based on {±d ₁ , ±d ₂ ,...,±d _m } to guarantee minimization. Specifically, if The subsets in {d ₁ ,d ₂ ,...,d _b } satisfy d ₁ +d ₂ +...+d _b =d _c , then replace { _{d 1} ,d ₂ ,... ,d _b } makes the constructed path the shortest, so as to obtain a new path and removed in FO and LO

Step 3, secret sharing initialization: Before deploying nodes to VANET, each node is allocated a set of public key and private key pairs using the RSA cryptographic algorithm. In addition, a non-zero random number is chosen for each path to mark the corresponding path.

In this embodiment, two large prime numbers p and q are selected first, and a prime order cyclic group G is selected, where g is a generator in the group G. Then, before the nodes are deployed to VANET, each node is assigned a public key (PK _i ,n) and a private key (SK _i ,n) using the RSA cryptographic algorithm, where i is the node subscript and n is p and q The product of , PK _i and (p-1)(q-1) are relatively prime, PK _i SK _i =1mod(p-1)(q-1). Finally, 2m non-zero elements r ₁ , r ₂ , ..., r _2m are randomly selected from the finite field GF(p) as the common information of the 2m paths.

Step 4, sub-key generation: select a univariate polynomial, and the constant term is the symmetric encryption key of the encrypted message; generate a sub-key for each path through this polynomial;

In this embodiment, in order to realize the (t, 2m) secret sharing scheme of 2m paths from the starting node S to the target node E, a t-1 order unary polynomial f(x)=a ₀ +a ₁ x+ is constructed. a ₂ x ² +...+a _t-1 x ^t-1 , where a ₁ ,a ₂ ,...,a _t-1 are random non-zero integers in GF(p), and a ₀ is a symmetric encryption key k. In order to share the symmetric key k and the message M with the target node E, the starting node S generates 2m subkeys k _i for 2m paths. _ki is calculated as follows:

Step 5, secret sharing: After encrypting the original message using symmetric encryption, the ciphertext is also divided into multiple parts, and each part corresponds to a path. Additionally, to support fault tolerance, a commitment is computed for each subkey. In order to transmit data in the open channel, use the public key of the target node to encrypt the sub-key, and select the current timestamp to resist replay attacks, and use the cryptographic one-way hash function to ensure the validity of the transmitted data. The corresponding data obtained are transmitted from the start node to the target node through various paths.

In this embodiment, the message M is symmetrically encrypted using the key k, and the ciphertext is divided into 2m parts, namely M ₁ , M ₂ , . . . , M _2m . Furthermore, a commitment _wi is computed for each subkey, i=1,2,...,2m. w _i is calculated as follows:

In order to transmit the symmetric key k and the message M from the originating node S to the destination node E through the open channel, the following procedures are required to protect the security and authenticity of the transmitted information. First, the subkey _ki is encrypted using the public key PK _e of the target node E. Subsequently, to resist replay attacks, the current timestamp T is chosen. Next, h( _ki , _wi ,T) is calculated using the cryptographic one-way hash function h(·) to ensure the validity of the transmitted information. Finally, the information is transmitted through 2m paths

Step 6, authentication: after receiving the data from each path, the target node first obtains the current timestamp, and verifies the validity of the timestamp in the received data according to the actual system requirements on the tolerance range limit; after the verification is successful, the target node Use its own private key to decrypt to obtain the sub-key, and verify the validity of the promise by checking the hash value; then, the target node uses the promise to judge the validity of the sub-key; if the sub-key is invalid, perform the error detection in step 7; If the subkey is valid, skip step 7;

In this embodiment, after receiving information from each path, the target node E obtains the current timestamp T', and proves that the received timestamp is valid by verifying |T'-T|<T _exp , where T _exp is the expected delay time, It can be controlled within the tolerable range according to the actual system requirements. Subsequently, E uses the private key SK _i to calculate And by verifying that the equation h(k′ _i , _wi , T)=h(k _i , _wi , T) holds, the promise _wi is valid. In addition, E judges the validity of the subkey _ki in the path _Pi by verifying the formula (3).

If the above formula holds, the subkey _ki is valid, that is, _ki can be used to reconstruct the symmetric key k. Otherwise k _i cannot be used for reconstruction, and the error detection in step 7 is performed.

Step 7, error detection: if the number of successfully verified subkeys does not meet the specified requirements, the target node will send an error report to the starting node; the starting node will verify the validity of the received error report and transmit it correctly. The data path returns information to the target node; the target node verifies the validity of the returned information. If the originating node does not return a message within the specified time or the number of failed verifications of the target node exceeds a certain value, the originating node is considered a malicious node and the communication with the originating node is terminated;

Due to the actual situation, the attacker can not only eavesdrop on the communication channel, but also block, forward or tamper with the channel. Furthermore, if the originating node S is itself an attacker, it will deliberately generate invalid subkeys to interfere or disrupt VANET communications. Therefore, high fault tolerance is an essential part of a robust scheme.

In this embodiment, if equation (3) does not hold, there is at least one attacker in the system. However, due to the use of (t, 2m) secret sharing, E can reconstruct a valid symmetric key as long as there are t or more paths that make equation (3) true. After obtaining this symmetric key, S and E can communicate via encrypted messages. If there are no t or more paths that make equation (3) true, E sends an error report to S. After S successfully verifies the validity of the error report, it will transfer the information within T _exp time through a safe transmission path sent to E. Subsequently, E checks the validity of _ki . In the above process, if S is not returned within T _exp Or the number of verification failures exceeds a certain number, then S is regarded as a malicious node, and E terminates the communication with S.

Step 8, key reconstruction: the target node reconstructs the symmetric key by using the valid sub-keys transmitted by the number of paths not less than the threshold value, and decrypts the ciphertext to obtain the original message.

In this embodiment, the target node E can reconstruct the symmetric key through subkeys obtained in t or more paths, and the calculation method is as follows:

Then, the message M can be decrypted with the symmetric key k. However, if the number of subkeys is less than t, the message M cannot be recovered.

In the multi-path communication method based on secret sharing in the vehicle ad hoc network environment, the ciphertext of the communication information is decomposed into multiple parts between two nodes, and the information is transmitted through multiple channels respectively, which reduces the transmission process of a single network. load, reduce the delay, and solve the problem that the target node receives information too lag. This information transmission method can timely analyze the current road traffic environment and provide corresponding intelligent traffic services.

Further, the communication method can solve the situation that the attacker can destroy the communication by attacking the information transmission of a single path, thereby reducing the security risk of the network. It can effectively prevent criminals from using the stolen private data to seek illegal benefits, protect the legitimate rights and interests of users, and prevent the loss of users' economic property.

This communication method also has high fault tolerance. Even if unstable factors such as network congestion, traffic restriction, and node equipment damage occur in the VANET, this communication method can still provide normal service functions within this time period.

The above are only preferred embodiments of the present invention, and the protection scope of the present invention is not limited to the above-mentioned embodiments, and all technical solutions that belong to the idea of the present invention belong to the protection scope of the present invention. It should be pointed out that for those skilled in the art, some improvements and modifications without departing from the principle of the present invention should be regarded as the protection scope of the present invention.

Claims (10)

1. a multi-path communication method based on secret sharing under a vehicle-mounted ad hoc network environment, is characterized in that: utilize the Latin square matrix to find a plurality of disjoint paths between the starting node and the target node, and then utilize secret sharing to encrypt the symmetric encryption key. Divided into multiple sub-keys; the encrypted message is also divided into multiple parts, and an equal amount of commitment is generated for each sub-key to support fault tolerance; the encrypted sub-key, ciphertext, and commitment are jointly transmitted to the target through various paths node; the target node reconstructs the key using the subkey, and uses the key to decrypt the ciphertext to obtain the original message. Specific steps are as follows: Step 1, construct a Latin square matrix: construct a Latin square matrix based on the number of different elements in the logical transmission path; Step 2, determine the transmission path: determine multiple disjoint transmission paths between the start node and the target node according to the Latin square matrix, the logical transmission path and the two dynamic operation sets; Step 3, secret sharing initialization: use the RSA cryptographic algorithm to assign a set of public key pair and private key pair to each node; at the same time, select a non-zero random number for each path to mark the corresponding path; Step 4, sub-key generation: select a univariate polynomial, and the constant term is the symmetric encryption key of the encrypted message; generate a sub-key for each path through this polynomial; Step 5, secret sharing: After encrypting the original message using symmetric encryption, the ciphertext is also divided into multiple parts, each part corresponds to a path; a commitment is calculated for each subkey to support fault tolerance; To transmit data, use the public key of the target node to encrypt the sub-key, select the current timestamp to resist replay attacks, and use the cryptographic one-way hash function to ensure the validity of the transmitted data; The start node transmits to the target node; Step 6, authentication: after receiving the data from each path, the target node first obtains the current timestamp, and verifies the validity of the timestamp in the received data according to the actual system requirements on the tolerance range limit; after the verification is successful, the target node Use its own private key to decrypt to obtain the sub-key, and verify the validity of the promise by checking the hash value; then, the target node uses the promise to judge the validity of the sub-key; if the sub-key is invalid, perform the error detection in step 7; If the subkey is valid, skip step 7; Step 7, error detection: if the number of successfully verified subkeys does not meet the specified requirements, the target node will send an error report to the starting node; the starting node will verify the validity of the received error report and transmit it correctly. The data path returns information to the target node; the target node verifies the validity of the returned information. If the originating node does not return a message within the specified time or the number of failed verifications of the target node exceeds a certain value, the originating node is considered a malicious node and the communication with the originating node is terminated; Step 8, key reconstruction: the target node reconstructs the symmetric key by using the valid sub-keys transmitted by the number of paths not less than the threshold value, and decrypts the ciphertext to obtain the original message. 2. the multi-path communication method based on secret sharing under a kind of vehicle-mounted ad hoc network environment according to claim 1 is characterized in that: with 2-CN network as communication model, the 2-CN network is modeled as an undirected graph G(n,±d ₁ ,±d ₂ ,...,±d _m ), where n is the number of nodes in the graph, represented by 1, 2,...,n respectively, ±d ₁ to ±d _m respectively represent the distance between each node and the adjacent 2m nodes in the undirected graph, and At this time, there are 2m shortest and node-disjoint paths, let LTP(S, E, SE) be the logical transmission path, representing the logical path from the starting node S to the target node E through the operation sequence SE, where the operation sequence SE={ d ₁ ,d ₂ ,...,d _j } is a subset of {±d ₁ ,±d ₂ ,...,±d _m }; based on the undirected graph G(n,±d ₁ ,±d ₂ ,...,±d _m ), each node has 2m adjacent nodes, in order to find the disjoint path of 2m nodes, the first set of operations is FO={±d ₁ ,±d ₂ , ...,±d _m }, the set of last operations is LO. 3. the multi-path communication method based on secret sharing under a kind of vehicle-mounted ad hoc network environment according to claim 2, is characterized in that: the concrete steps of constructing Latin square matrix in described step 1 are as follows: based on different elements in SE Construct a Latin square matrix with the number of , let FO=LO= _{ ±d ₁ ,±d ₂ ,...,±d _{m }} , the number of different elements in SE is d _j' is used as the first row element of the Latin square matrix, the subsequent j'-1 rows are all based on the previous row, and the first element in the previous row is moved to the end, and the other elements are moved forward one place in sequence, and finally a j '×j' Latin square matrix. 4. the multi-path communication method based on secret sharing under a kind of vehicle-mounted ad hoc network environment according to claim 3, is characterized in that: the concrete step of determining transmission path in described step 2 is as follows: ' elements are inserted into the middle of each row in the Latin square matrix to obtain j' node disjoint paths, and remove the same elements as SE in FO and LO; For the set FO that contains pairs of forward and reverse operations d' and -d', randomly select a P _i from the existing j' paths, 0<i≤j', and add the two operations to the original There are two new paths d'||{P _i }||-d' and -d'||{P _i }||d', and remove d in FO and LO ' and -d'; since the forward and reverse operations performed simultaneously on any node in the graph G(n,±d ₁ ,±d ₂ ,...,±d _m ) can cancel each other out, the correct get new path; For the remaining single operations in FO Add it to the front and back of the original operation at the same time; in order to ensure that the path can reach the target node E, it is necessary to reverse the two operations added to the middle of the operation, i.e. the described operation Merge based on {±d ₁ , ±d ₂ ,...,±d _m } to guarantee minimization, if The subsets in {d ₁ ,d ₂ ,...,d _b } satisfy d ₁ +d ₂ +...+d _b =d _c , then replace { _{d 1} ,d ₂ ,... ,d _b } makes the constructed path the shortest, so as to obtain a new path and removed in FO and LO 5. the multi-path communication method based on secret sharing under a kind of vehicle-mounted ad hoc network environment according to claim 4 is characterized in that: the concrete steps of secret sharing initialization in described step 3 are as follows: select two large prime numbers p and q, select a prime order cyclic group G, where g is a generator in the group G; Before node deployment, each node is assigned a public key (PK _i ,n) and a private key (SK _i ,n) using the RSA cryptographic algorithm, where i is the node subscript, n is the product of p and q, and PK _i is relatively prime to (p-1)(q-1), PK _i SK _i =1mod(p-1)(q-1); Randomly select 2m non-zero elements r ₁ , r ₂ ,...,r _2m from the finite field GF(p) as the common information of the 2m paths. 6. the multi-path communication method based on secret sharing under a kind of vehicle-mounted ad hoc network environment according to claim 5, is characterized in that: the concrete steps that the sub-key is generated in described step 4 are as follows: construct a t-1 Order univariate polynomial f(x)=a ₀ +a ₁ x+a ₂ x ² +...+a _t-1 x ^t-1 , where a ₁ ,a ₂ ,...,a _t-1 is GF The random non-zero integer in (p), a ₀ is the symmetric key k; the starting node S generates 2m subkeys k _i for 2m paths, which are used to share the symmetric key k and the message M, k with the target node E _i is calculated as follows: 7. the multi-path communication method based on secret sharing under a kind of vehicle-mounted ad hoc network environment according to claim 6, is characterized in that: the concrete steps of secret sharing in described step 5 are as follows: use key k to message M Perform symmetric encryption, and divide the ciphertext into 2m parts, namely M ₁ , M ₂ ,..., M _2m ; Calculate a commitment _wi for each subkey, i=1,2,...,2m; _wi is calculated as follows: When transmitting the symmetric key k and message M from the starting node S to the target node E through the open channel, the security and authenticity of the transmitted information need to be protected. The specific process is as follows: S1, use the public key PK _e of the target node E to encrypt the subkey _ki ; S2, in order to resist replay attacks, select the current timestamp T; S3, use the cryptographic one-way hash function h(·) to calculate h(k _i , w _i , T) to ensure the validity of the transmitted information; S4, transmit information through 2m paths 8. the multi-path communication method based on secret sharing under a kind of vehicle-mounted ad hoc network environment according to claim 7, is characterized in that: the concrete steps of authentication in described step 6 are as follows: after receiving information from each path , the target node E obtains the current timestamp T', and proves that the received timestamp is valid by verifying that |T'-T|<T _exp , where T _exp is the expected delay time; E is calculated using the private key SK _i And by verifying that the equation h(k′ _i , _wi , T) = h( _ki , _wi , T) is established to prove that the commitment _wi is valid; E judges the validity of the sub-key _ki in the path _Pi by the verification formula, and the verification formula is as follows: If the above formula holds, the sub-key _ki is valid, that is, _ki can be used to reconstruct the symmetric key k, otherwise _ki cannot be used for reconstruction, and the error detection in step 7 is performed. 9. the multi-path communication method based on secret sharing under a kind of vehicle-mounted ad hoc network environment according to claim 8, is characterized in that: the concrete steps of error detection in described step 7 are as follows: when S and E communicate , due to the use of (t, 2m) secret sharing, if there are t or more paths that can make the verification formula (3) true, E can reconstruct a valid symmetric key. After obtaining this symmetric key, S and E can communicate through encrypted messages; If there are no t or more paths to verify (3), E sends an error report To S, after S successfully verifies the validity of the error report, it passes through a safe transmission information path that has established the verification formula (3), within the time T _exp Send to E; then, E checks the validity of _ki ; if S does not return within T _exp Or the number of verification failures exceeds a certain number, then S is regarded as a malicious node, and E terminates the communication with S. 10. The multi-path communication method based on secret sharing under a kind of vehicle-mounted ad hoc network environment according to claim 9, it is characterized in that: the concrete steps of key reconstruction in described step 8 are as follows: target node E passes t The symmetric key is reconstructed from subkeys obtained in one or more paths, calculated as follows: Subsequently, the message M can be obtained by decrypting the symmetric key k; if the number of subkeys is less than t, the message M cannot be recovered.