CN116248725A - Blockchain node sharding method for node collaborative storage in the Internet of Vehicles environment - Google Patents

Abstract

The application relates to a block chain node slicing method for node collaborative storage in an Internet of vehicles environment. The method comprises the following steps: all nodes in the block chain system solve the workload proving difficult problem to determine each member node and a leading node in the catalogue committee, each member node operates NSGA-II algorithm, and the corresponding optimal fragmentation result is obtained and sent to the leading node; the leader node selects the best slicing result with the smallest communication delay difference from the best slicing results according to the best slicing results and broadcasts the best slicing result to other nodes in the catalogue committee; other nodes in the catalogue committee perform confirmation signature; when the leader node receives a message of 2 or morehUnder the condition of confirming the signature of 3 nodes, the catalogue committee achieves consensus and the fragmentation is completed; otherwise, reselecting the leading node for slicing until the catalogue committeeConsensus is reached to generate a shard result list and determine a cooperative group partitioning result list for each shard, thereby reducing communication delay between nodes within the shard.

Description

Blockchain node sharding method for node collaborative storage in Internet of Vehicles environment

Technical Field

The present application relates to the field of Internet of Things technology, and in particular to a blockchain node sharding method for node collaborative storage in an Internet of Vehicles environment.

Background Art

With the development of the Internet of Things, the Internet of Vehicles has gradually become an important application in technology and industry. The Internet of Vehicles (IoV) is a large-scale integrated network for wireless communication and information exchange between people, vehicles and roads. The Internet of Vehicles can significantly improve traffic efficiency, reduce energy consumption and reduce traffic accidents. Usually, the Internet of Vehicles consists of smart vehicles, roadside units (RSU), trusted authorities (TA) and data centers (DC). RSU is usually a road infrastructure fixed on the roadside, TA is usually a trusted server, and DC is used to store all information related to the Internet of Vehicles. When a vehicle enters the communication range of the RSU, it will automatically communicate with the RSU through a wireless channel using a dedicated short-range communication protocol. Wired channels are usually used between each TA and between TA and DC. After the vehicle establishes a connection with the TA through the RSU, it can upload its location, vehicle status and other information to the TA, and can also receive information such as traffic information from the TA to plan its own driving route.

In the Internet of Vehicles, mobile vehicles will continuously generate a large amount of different types of data. Data sharing between vehicles plays a vital role in improving driving safety and enhancing in-vehicle services. However, in data sharing, it is easy to cause problems such as data security and privacy information leakage. Based on the above problems, the combination of blockchain technology and the Internet of Vehicles can utilize the technical characteristics of blockchain decentralization, blockchain anonymity, immutability and traceability to ensure the privacy, security and integrity of data sharing. The encryption algorithm in the blockchain is used to form an effective access control, which can effectively solve the problem of unauthorized access to shared data between vehicles. With the help of blockchain's smart contract technology, vehicles can adaptively customize appropriate sharing rules based on their own resource status and shared data characteristics, truly realize user-autonomous data sharing, and reduce the pressure of user data management in the Internet of Vehicles. However, due to the limited resources of Internet of Vehicles devices (RSU, etc.) (such as limited storage space), poor scalability of blockchain in the Internet of Vehicles, and low throughput, the application of blockchain in the Internet of Vehicles is limited. In addition, due to the gradual popularization of 5G mobile communications and the explosive growth of the number of Internet of Vehicles devices, there is an urgent need to improve the scalability and throughput of blockchain systems.

Solutions to blockchain scalability are generally divided into three categories: sidechains, sharding, and directed acyclic graphs. Among them, sharding technology is a very promising solution. Sharding technology is divided into three types: node sharding, transaction sharding, and state sharding. Among them, node sharding is to divide the nodes in the traditional blockchain into many small shards, and each shard processes the transactions submitted to the blockchain in parallel, so as to improve the scalability of the blockchain system. Each shard can be regarded as a small blockchain. The nodes within each shard independently verify the transactions within the shard. After all nodes in the shard reach a consensus, the transactions are packaged into micro-blocks. Each shard will generate micro-blocks, and the directory committee will collect all micro-blocks and verify them, and finally generate a complete block and submit it to the blockchain. Therefore, in theory, the transaction throughput of the blockchain can be increased several times.

In related technologies, although sharding technology can improve the scalability of blockchain systems, the use of blockchain sharding technology in the Internet of Vehicles adopts a sharding scheme with random node division, which easily leads to the problem of malicious nodes gathering in the same shard, thereby affecting the security of the shard. In order to solve the problem of sharding security, a sharding model based on trust value is proposed, which uses reputation to characterize the heterogeneity between nodes, which can improve the security of sharding, but ignores the problem of communication delay between nodes in the shard.

Therefore, the communication delay between nodes in the current blockchain node sharding method is relatively high.

Summary of the invention

Based on this, it is necessary to provide a blockchain node sharding method for node collaborative storage in the Internet of Vehicles environment, which can reduce the communication delay between nodes in response to the above technical problems.

A blockchain node sharding method for node collaborative storage in an Internet of Vehicles environment, the method comprising:

All nodes in the blockchain system solve the proof-of-work problem, and the first h nodes that solve the proof-of-work problem are determined as member nodes of the directory committee;

Randomly select a leader node of the directory committee from each of the member nodes;

Each of the member nodes runs the NSGA-II algorithm to obtain the best sharding result for each of the member nodes;

Each of the member nodes sends its own best sharding result to the leader node;

The leader node selects the best sharding result with the smallest communication delay difference from each best sharding result, and broadcasts the best sharding result with the smallest communication delay difference to other nodes in the directory committee;

Other nodes in the directory committee confirm the signature based on the best shard result with the smallest communication delay difference received;

When the leader node receives confirmation signatures from more than or equal to 2 h /3 nodes, the directory committee reaches a consensus and sharding is completed;

When the leader node receives confirmation signatures from less than 2 h /3 nodes, it returns to the step of randomly selecting the leader node of the directory committee from each of the member nodes until the leader node receives confirmation signatures from more than or equal to 2 h /3 nodes, the directory committee reaches a consensus, the sharding is completed, and a sharding result list is generated;

According to the sharding result list, the nodes in each shard are divided into cooperative groups, and a cooperative group division result list of each shard is determined.

In one embodiment, before all nodes in the blockchain system solve the proof-of-work problem and the first h nodes that solve the proof-of-work problem are determined as member nodes of the directory committee, the process further includes:

Analyze all nodes in the blockchain system to determine malicious nodes and the total number of malicious nodes in the blockchain system;

Determining whether a proportion of malicious nodes in the blockchain system is greater than one-third based on the total number of nodes in the blockchain system and the total number of malicious nodes in the blockchain system;

When the proportion of malicious nodes in the blockchain system is greater than one-third, removing q malicious nodes from the blockchain system;

，

为需要移除的恶意节点个数，m为区块链系统中的恶意节点个数，N为区块链系统中的节点总数，Δ为区块链系统中恶意节点的比例。in,

,

is the number of malicious nodes that need to be removed, m is the number of malicious nodes in the blockchain system, N is the total number of nodes in the blockchain system, and Δ is the proportion of malicious nodes in the blockchain system.

In one embodiment, the objective function of the NSGA-II algorithm is:

；

;

为分片间节点数量的差异，

为分片间的恶意节点比例差异，

为分片间的通信延迟差异，

为分片间的存储空间差异，Ω为节点划分的解空间，X为成员节点的最佳分片结果，R为最佳分片结果中分片内恶意节点的比例。in,

is the difference in the number of nodes between shards,

is the difference in the proportion of malicious nodes between shards,

is the communication delay difference between shards,

is the storage space difference between shards, Ω is the solution space of node partition, X is the best sharding result of member nodes, and R is the proportion of malicious nodes in the shard in the best sharding result.

的计算方式为：In one embodiment, the difference in the number of nodes between the shards

The calculation method is:

；

;

为分片j中的节点数，h为区块链系统中的分片数。in,

is the number of nodes in shard j , and h is the number of shards in the blockchain system.

的计算方式为：In one embodiment, the difference in the proportion of malicious nodes between the shards

The calculation method is:

；

;

；

;

为分片j的恶意节点比例，E _j 为分片j内恶意节点数。in,

is the ratio of malicious nodes in shard j , _and Ej is the number of malicious nodes in shard j .

的计算方式为：In one embodiment, the communication delay difference between the shards

The calculation method is:

；

;

为分片j内所有节点到分片领导节点u的通信延迟差异，

为领导节点u到节点i的通信延迟，g _j 为分片j的节点总数，

为分片领导节点u接收到节点i回复的时刻，

为分片领导节点u发送信息给节点i的时刻。in,

is the difference in communication delay from all nodes in shard j to shard leader node u ,

is the communication delay from leader node u to node i , gj _is the total number of nodes in shard j ,

is the time when the shard leader node u receives the reply from node i ,

The time when the shard leader node u sends information to node i .

的计算方式为：In one embodiment, the storage space difference between the shards

The calculation method is:

；

;

为分片j内节点的存储空间，c _i 为节点i的存储空间大小。in,

is the storage space of the node in shard j , _and ci is the storage space size of node i .

In one embodiment, dividing the nodes in each shard into cooperative groups according to the shard result list to determine the cooperative group division result list of each shard includes:

Remove the nodes whose available storage space in shard j is greater than _the storage space Fj required by shard j from the shard result list;

The leader node of the directory committee broadcasts a notification of starting team formation;

After receiving the notification to start teaming, the node in shard j immediately broadcasts the teaming request to other nodes in shard j ;

When node i in shard j receives a message from node b agreeing to form a team, it calculates the available storage space of node i and node b . If the sum of the available storage space of node i and node b is greater than F _j , the team formation ends;

If the sum of available storage space of node i and node b is less than or equal to F _j , then continue to wait for teaming consent messages from other nodes until the sum of available storage space of node i and the nodes that agree to teaming is greater than F _j ;

When all nodes of each shard in the shard result list have completed teaming or the sum of available storage space of the remaining unteamed nodes of each shard is less than F , the division of the collaboration groups of each shard is completed, and the remaining unteamed nodes of each shard will be used as candidate nodes of each shard.

The blockchain node sharding method for node cooperative storage in the above-mentioned Internet of Vehicles environment solves the proof-of-work problem through all nodes in the blockchain system, and the first h nodes that solve the proof-of-work problem are determined as the member nodes in the directory committee, and the leader node of the directory committee is randomly selected from each of the member nodes, and then each of the member nodes runs the NSGA-II algorithm to obtain the best sharding result of each member node, and sends each of the best sharding results to the leader node; thereby, the leader node selects the best sharding result with the smallest communication delay difference from each best sharding result, and broadcasts the best sharding result with the smallest communication delay difference to other nodes in the directory committee; other nodes in the directory committee confirm the signature based on the received best sharding result with the smallest communication delay difference; when the leader node receives confirmation signatures of more than or equal to 2 h /3 nodes, the directory committee reaches a consensus and the sharding is completed; when the leader node receives confirmation signatures of less than 2 h /3 nodes, it returns to the step of randomly selecting the leader node of the directory committee from each of the member nodes until the leader node receives confirmation signatures of more than or equal to 2 h /3 nodes. /3 nodes’ confirmation signatures, the directory committee reaches a consensus, the sharding is completed, and a sharding result list is generated; then, according to the sharding result list, the nodes in each shard are divided into collaborative groups, and the collaborative group division result list of each shard is determined, thereby obtaining the sharding result with the smallest communication delay difference, improving the transaction throughput of the blockchain, and reducing the communication delay between nodes in the shard.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a flow chart of a blockchain node sharding method for node collaborative storage in an Internet of Vehicles environment in one embodiment;

FIG2 is a schematic diagram of the structure of a blockchain node sharding method for node collaborative storage in an Internet of Vehicles environment in one embodiment.

DETAILED DESCRIPTION

In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

In one embodiment, as shown in FIG. 1 and FIG. 2 , a blockchain node sharding method for node collaborative storage in an Internet of Vehicles environment is provided, comprising the following steps:

In step S220, all nodes in the blockchain system solve the proof-of-work problem, and the first h nodes that solve the proof-of-work problem first are determined as member nodes in the directory committee.

Among them, all nodes in the blockchain system may include roadside units, and all nodes in the blockchain system may also include roadside units and trusted institutions. The roadside units in the Internet of Vehicles are responsible for receiving, processing and broadcasting messages sent by vehicles.

The Directory Committee is responsible for collecting micro-blocks packaged by each shard and merging them into blocks to be published in the blockchain system, and is responsible for dividing nodes into different shards. The member nodes of the Directory Committee are composed of the leader nodes of the shards.

Among them, the leader node of the shard is responsible for the transaction distribution and verification result collection of the current shard, and generates micro-blocks based on the transaction verification results and submits them to the directory committee.

Among them, a micro-block can be a collection of transactions formed after transactions are verified and consensus is reached in the shards.

It should be understood that a node needs to solve a proof-of-work (PoW) problem if it wants to join the blockchain system. When the blockchain system is initialized, all nodes in the blockchain system solve the PoW problem, and the first h nodes that solve the problem are elected as member nodes of the directory committee.

Step S240: randomly select a leader node of the directory committee from each member node.

The leader node (denoted as L) of the directory committee is randomly generated from the member nodes of the directory committee. Each member node of the directory committee is the leader node of each shard.

Step S260: Each member node runs the NSGA-II algorithm to obtain the best sharding result of each member node.

Among them, the NSGA-II algorithm is one of the most popular multi-objective genetic algorithms. It reduces the complexity of the non-inferior sorting genetic algorithm and has the advantages of fast running speed and good convergence of the solution set. Therefore, the NSGA-II algorithm is selected to solve the fragmentation results.

In one embodiment, the NSGA-II algorithm shards nodes based on the number of nodes in the shard, whether the node is malicious, the size of the communication delay between the node and the leader node of the shard (referred to as communication delay), and the size of the node storage space in the shard. The optimization goals of the NSGA-II algorithm are: 1) the difference in the number of nodes between shards; 2) the difference in the proportion of malicious nodes between shards; 3) the difference in communication delay between shards; 4) the difference in storage space between shards. The member nodes of the directory committee each run the NSGA-II algorithm to calculate the difference in the number of nodes between shards, the difference in the proportion of malicious nodes between shards, the difference in communication delay between shards, and the difference in storage space between shards, and perform minimization optimization, and each member node finally obtains its own optimal sharding result.

In one embodiment, the objective function of the NSGA-II algorithm is:

；

;

为分片间节点数量的差异，

为分片间的恶意节点比例差异，

为分片间的通信延迟差异，

为分片间的存储空间差异，Ω为节点划分的解空间，X为成员节点的最佳分片结果，R为最佳分片结果中分片内恶意节点的比例。in,

is the difference in the number of nodes between shards,

is the difference in the proportion of malicious nodes between shards,

is the communication delay difference between shards,

is the storage space difference between shards, Ω is the solution space of node partition, X is the best sharding result of member nodes, and R is the proportion of malicious nodes in the shard in the best sharding result.

It should be understood that the optimization goal of the objective function of the NSGA-II algorithm is designed to minimize the difference in the number of nodes between shards, the difference in communication delay between shards, the difference in the proportion of malicious nodes between shards, and the difference in storage space between shards. The malicious nodes in the blockchain system can be evenly distributed to each shard, reducing the difference in the proportion of malicious nodes in each shard, thereby avoiding malicious nodes from gathering in the same shard and causing the blockchain system to fail. Nodes with lower communication delays between each other can also be divided into the same shard, and the difference in the number of nodes between shards and the difference in storage space between shards can be reduced, reducing the transaction processing delay within the same shard, ensuring balanced configuration between shards, and avoiding the situation where the directory committee spends a long time waiting due to the low performance of a certain shard.

It should be understood that reducing the difference in the number of nodes between shards can ensure similar transaction processing speeds between shards.

It should be understood that reducing the difference in the proportion of malicious nodes between shards can ensure the security of each shard and prevent malicious nodes from gathering in the same shard, causing the shard to fail. In order to improve the security of shards and prevent malicious nodes from entering the same shard in large numbers, causing the shard to be less secure, it is necessary to consider the difference in the proportion of malicious nodes between shards.

越小，代表分片之间通信延迟差异越小，反之，则代表分片之间通信延迟差异大，通信延迟低的分片可以更早提交微区块，而通信延迟高的分片形成微区块的时间较长，进而较晚地提交微区块，造成微区块之间等待时间过长，降低系统吞吐量。It should be understood that after the directory committee of the blockchain system is formed, each member node in the directory committee serves as the leader node of each shard. Reducing the communication delay between the nodes in each shard and the leader node of the shard can increase the speed of transaction processing in the shard, thereby increasing the transaction throughput in the shard. In order to reduce the difference in communication delay between shards and improve the system throughput, it is necessary to ensure that the difference in communication delay between shards is as small as possible.

The smaller it is, the smaller the difference in communication delay between shards is. Conversely, the larger the difference in communication delay between shards is, the shards with low communication delay can submit micro-blocks earlier, while the shards with high communication delay take longer to form micro-blocks and submit micro-blocks later, resulting in long waiting time between micro-blocks and reduced system throughput.

It should be understood that in order to ensure security, in addition to reducing the difference in the proportion of malicious nodes between shards, the difference in the number of collaboration groups between shards can also be reduced. By reducing the difference in storage space between shards, it is indirectly ensured that each shard has a similar number of collaboration groups.

的计算方式为：In one embodiment, the difference in the number of nodes between shards

The calculation method is:

；

;

为分片j中的节点数，h为区块链系统中的分片数。in,

is the number of nodes in shard j , and h is the number of shards in the blockchain system.

的值越小，代表分片间的节点数量的差异越小。in,

The smaller the value, the smaller the difference in the number of nodes between shards.

的计算方式为：In one embodiment, the difference in the proportion of malicious nodes between shards

The calculation method is:

；

;

为分片j的恶意节点比例，E _j 为分片j内恶意节点数。in,

is the ratio of malicious nodes in shard j , _and Ej is the number of malicious nodes in shard j .

的计算方式为：In one embodiment, the communication delay difference between shards

The calculation method is:

；

;

为分片j内所有节点到分片领导节点u的通信延迟差异，

为领导节点u到节点i的通信延迟，g _j 为分片j中协作组的数量，

为分片领导节点u接收到节点i回复的时刻，

为分片领导节点u发送信息给节点i的时刻。in,

is the difference in communication delay from all nodes in shard j to shard leader node u ,

is the communication delay from leader node u to node i , gj _is the number of collaboration groups in shard j ,

is the time when the shard leader node u receives the reply from node i ,

The time when the shard leader node u sends information to node i .

的计算方式为：In one embodiment, the storage space difference between the shards

The calculation method is:

；

;

为分片j内节点的存储空间，c _i 为节点i的存储空间大小。in,

is the storage space of the node in shard j , _and ci is the storage space size of node i .

Step S280: Each member node sends its best sharding result to the leader node.

Step S300: The leader node selects the best sharding result with the smallest communication delay difference from each best sharding result, and broadcasts the best sharding result with the smallest communication delay difference to other nodes in the directory committee.

Step S320: Other nodes in the directory committee confirm the signature based on the received best sharding result with the smallest communication delay difference.

Step S340: When the leader node receives confirmation signatures from more than or equal to 2 h /3 nodes, the directory committee reaches a consensus and the sharding is completed.

Step S360: When the leader node receives confirmation signatures from less than 2 h /3 nodes, it returns to the step of randomly selecting the leader node of the directory committee from each member node until the leader node receives confirmation signatures from more than or equal to 2 h /3 nodes, the directory committee reaches a consensus, the sharding is completed, and a sharding result list is generated.

Among them, sharding means that all nodes in the blockchain are divided into different sets according to certain rules, and each set is called a shard.

It should be understood that after sharding is completed, each shard independently verifies and confirms transactions, all shards process transactions in parallel, and the leader node of the shard is responsible for the distribution of transactions within the shard and the collection of verification results. The Directory Committee is responsible for collecting and verifying the micro-blocks submitted by each shard and packaging them on the chain.

In one embodiment, the execution of steps S220 to S380 is implemented by a sharding algorithm, and the sharding algorithm is shown in Algorithm 1:

。

.

The relevant comments of Algorithm 1 are as follows:

1) The third line indicates that all nodes in the blockchain system (denoted as L ) solve the PoW problem;

2) The 4th row indicates that the first h nodes that get the result first form the directory committee M ;

；3) Line 5 indicates that a node is randomly selected from the nodes of the directory committee as the leader node

;

；4) Lines 6-9 indicate that the nodes in M run the NSGA-II algorithm to obtain the best sharding result and send the best sharding result f to

;

从所有的f中挑选通信延迟最小的结果作为最佳结果

，并将

广播；5) Lines 11-12 indicate

From all f, select the result with the smallest communication delay as the best result

, and

broadcast;

为最佳分片结果的节点个数赋值给计数器

；6) Line 13 indicates that confirmation will be sent

Assign the counter the number of nodes in the best sharding result

;

对应的分片结果记录到分片结果列表Z，分片结束；7) Lines 14-16 indicate that if more than 2 h /3 nodes in M send confirmation signatures, then

The corresponding sharding results are recorded in the sharding result list Z , and the sharding ends;

确认签名到

的节点的个数小于2h/3，即共识失败，那么随机从目录委员会M挑选一个新的节点作为领导节点

。8) Line 18 indicates that if you send

Confirm signature to

If the number of nodes is less than 2 h /3, that is, the consensus fails, then a new node is randomly selected from the directory committee M as the leader node

.

In Algorithm 1, if P is the number of optimization targets of the NSGA-II algorithm and Q is the number of individuals in the population, the time complexity of the NSGA-II algorithm is O ( PQ ² ). Algorithm 1 has only one single loop, so the time complexity of Algorithm 1 is O ( hPQ ² ).

Step S380: divide the nodes in each shard into cooperative groups according to the shard result list, and determine the cooperative group division result list of each shard.

The nodes in the collaboration group can exchange information with each other. Multiple nodes with insufficient storage space can form a collaboration group, so that the sum of the storage space of the nodes in the collaboration group can meet the storage requirements of the blockchain.

It should be understood that in traditional sharded blockchains, nodes participating in consensus need to store the complete blockchain data of the shard in which they are located. The reason is that when verifying a transaction, the consensus node needs to compare the transaction information with the ledger information in the blockchain to determine whether the transaction is legal. However, this traditional solution for storing complete data is not suitable for the Internet of Vehicles environment because there are a large number of nodes with limited storage space in the Internet of Vehicles environment, and these nodes cannot store complete blockchain data. In order to reduce the storage pressure of nodes in the Internet of Vehicles, the nodes in each shard are divided into collaborative groups, and node collaborative storage is used to reduce the storage pressure of nodes in the Internet of Vehicles. The nodes in each shard are divided into collaborative groups, and nodes with smaller communication delays between each other can be divided into a collaborative group. The division of collaborative groups needs to satisfy the requirement that the available storage space in the collaborative group is greater than the required storage space in the shard.

In one embodiment, in order to ensure that there is enough space to store new blocks generated by shard j of the blockchain system in the future, _{the storage space Fj} required by shard j of the blockchain system is defined as:

；

;

表示区块链系统的分片j当前所占存储空间，

表示区块链系统的分片j的预留空间。预留空间用于区块链系统的分片j中新区块的存储，预留空间越大，代表当前协作组可以协作运行的时间越久。节点i的数据结构为：i=<ID，(x,y),c,B>，

，其中，ID代表节点的编号，(x,y)代表节点的二维坐标，c代表节点的存储空间大小，B代表节点存储的区块列表，g _j 为分片j的节点总数。in,

Indicates the current storage space occupied by shard j of the blockchain system,

Represents the reserved space of shard j of the blockchain system. The reserved space is used to store new blocks in shard j of the blockchain system. The larger the reserved space, the longer the current collaboration group can collaborate. The data structure of node i is: i = < ID , ( x , y ), c , B >,

, where ID represents the node number, ( x , y ) represents the two-dimensional coordinates of the node, c represents the storage space size of the node, B represents the block list stored by the node, _and gj is the total number of nodes in shard j .

Among them, the kth collaboration _group Gk in shard j can be expressed as:

；

;

表示节点i的存储空间大小，

表示区块链系统的分片j所需存储空间，β表示满足区块链系统的分片j所需存储空间要求的最小节点数，即β个节点的可用存储空间之和大于等于

，β-1个节点的可用存储空间之和小于

。如果当前区块链系统的分片j中所有节点的存储空间之和小于

，则无法组成协作组。in,

Indicates the storage space size of node i ,

represents the storage space required for shard j of the blockchain system, β represents the minimum number of nodes that meet the storage space requirements of shard j of the blockchain system, that is, the sum of the available storage space of β nodes is greater than or equal to

, the sum of available storage space of β -1 nodes is less than

If the sum of the storage space of all nodes in the current blockchain system's shard j is less than

, a collaborative group cannot be formed.

Among them, _the collaboration group set Sj in shard j is:

；

;

表示分片j中的协作组数量。每个分片内部独立进行交易的验证工作，具体的交易验证由协作组节点负责。in,

Indicates the number of collaboration groups in shard j . Each shard independently verifies transactions, and the specific transaction verification is the responsibility of the collaboration group node.

In one embodiment, according to the shard result list, the nodes in each shard are divided into cooperative groups, and the cooperative group division result list of each shard is determined, including:

The nodes whose available storage space in shard j is greater than _the required storage space Fj of shard j are removed from the shard result list; the leader node of the directory committee broadcasts a notification to start teaming; after receiving the notification to start teaming, the nodes in shard j immediately broadcast a request to team up to other nodes in shard j ; when node i in shard j receives a message from node b agreeing to team up, the available storage space of node i and node b is calculated, and if the sum of the available storage space of node i and node b is greater than Fj , the teaming is completed; if the sum of the available storage space of node _i and node b is less than or equal to Fj , continue to wait for the teaming agreement message from other nodes until the sum of the _available storage space of node i and the nodes agreeing to team up is greater than Fj _; when all the nodes of each shard in the shard result list have completed teaming or the sum of the available storage space of the remaining unteamed nodes of each shard is less than Fj , the division of the collaborative groups of each shard is completed, _and the remaining unteamed nodes of each shard will be used as candidate nodes of each shard.

Among them, according to the communication delay between nodes, nodes with smaller communication delay are divided into the same cooperation group, and at the same time, the total available storage space of the nodes in the cooperation group is guaranteed to be greater than F _j . When the available storage space of a node is greater than F _j , the node can be used as a cooperation group alone.

It should be understood that node i in shard j determines which node to team up with based on the received teaming agreement message, that is, node i in shard j teams up with the node whose teaming agreement message it receives first. Therefore, nodes with smaller communication delays with node i can be divided into the same collaboration group, that is, nodes with smaller communication delays between nodes are divided into the same collaboration group, thereby reducing the communication delay of the blockchain system.

The leader node of the collaboration group is generated randomly, and each node in the collaboration group maintains a node-block mapping table, which records the list of blocks stored by each node and the storage space utilization of each node. The storage space utilization refers to the ratio of the node's used storage space to the node's total storage space, denoted as r , as shown below:

；

;

代表节点的已用存储空间，

代表节点的总存储空间。当区块链系统产生新区块时，由协作组的组内领导节点根据组内各节点的存储空间利用率，选择存储空间利用率最小的节点存储新区块。当组内所有节点的存储空间利用率均大于99%时，由组内领导节点向分片的领导节点提出重新划分协作组的请求。协作组划分过程中，根据节点间的通信延迟的不同，将通信延迟小的节点划分到一个协作组中，同时满足组内节点的总存储空间大于F _j 。in,

Represents the used storage space of the node,

Represents the total storage space of the node. When the blockchain system generates a new block, the leader node of the collaboration group selects the node with the smallest storage space utilization to store the new block based on the storage space utilization of each node in the group. When the storage space utilization of all nodes in the group is greater than 99%, the leader node in the group submits a request to the leader node of the shard to re-divide the collaboration group. During the collaboration group division process, nodes with small communication delays are divided into one collaboration group based on the different communication delays between nodes, while satisfying that the total storage space of the nodes in the group is greater than F _j .

Among them, the leader node of the shard broadcasts the transaction that needs to be verified to the member nodes in the shard, and the member nodes (source nodes) start to verify after receiving the transaction. If the locally stored information can meet the requirements of transaction verification, the node verifies the transaction locally, and the transaction only needs to be attached with the signature of the source node. If the locally stored information cannot verify the transaction, it is necessary to send a data sharing request to other nodes in the collaboration group. After receiving the request, the node (target node) that has the data required by the source node sends its own signature and the information required by the source node to the source node. The source node verifies the transaction based on the received information and local information. After the verification is passed, the signature of the source node and the signature of the target node are attached to the verification information and sent to the leader node of the shard.

It should be understood that by dividing the nodes with smaller communication delays between nodes in the shard into the same collaboration group, each node in the traditional blockchain system that stores all the blockchain information of the shard in which it is located can be optimized to a group of nodes that store all the blockchain information of the shard in which it is located, so that nodes with insufficient storage space can also participate in the blockchain consensus work.

The blockchain node sharding method for node cooperative storage in the above-mentioned Internet of Vehicles environment solves the proof-of-work problem through all nodes in the blockchain system, and the first h nodes that solve the proof-of-work problem are determined as the member nodes in the directory committee, and the leader node of the directory committee is randomly selected from each member node, and then each member node runs the NSGA-II algorithm to obtain the best sharding result of each member node, and sends their respective best sharding results to the leader node; thus, the leader node selects the best sharding result with the smallest communication delay difference from each best sharding result, and broadcasts the best sharding result with the smallest communication delay difference to other nodes in the directory committee; other nodes in the directory committee confirm the signature based on the received best sharding result with the smallest communication delay difference; when the leader node receives confirmation signatures greater than or equal to 2 h /3 nodes, the directory committee reaches a consensus and the sharding is completed; when the leader node receives confirmation signatures less than 2 h /3 nodes, it returns to the step of randomly selecting the leader node of the directory committee from each member node until the leader node receives confirmation signatures greater than or equal to 2 h /3 nodes. /3 nodes’ confirmation signatures, the directory committee reaches a consensus, the sharding is completed, and a sharding result list is generated; then, based on the sharding result list, the nodes in each shard are divided into collaborative groups, and the collaborative group division result list of each shard is determined. Thus, the sharding result with the smallest communication delay difference is obtained, which improves the transaction throughput of the blockchain and reduces the communication delay between nodes in the shard.

In one embodiment, before all nodes in the blockchain system solve the proof-of-work puzzle and the first h nodes that solve the proof-of-work puzzle are determined as member nodes of the directory committee, the process further includes:

Analyze all nodes in the blockchain system to determine malicious nodes in the blockchain system and the total number of malicious nodes; determine whether the proportion of malicious nodes in the blockchain system is greater than one third based on the total number of nodes in the blockchain system and the total number of malicious nodes in the blockchain system; if the proportion of malicious nodes in the blockchain system is greater than one third, remove q malicious nodes from the blockchain system;

，q为需要移除的恶意节点个数，m为区块链系统中的恶意节点个数，N为区块链系统中的节点总数，Δ为区块链系统中恶意节点的比例。in,

, q is the number of malicious nodes that need to be removed, m is the number of malicious nodes in the blockchain system, N is the total number of nodes in the blockchain system, and Δ is the proportion of malicious nodes in the blockchain system.

It should be understood that since this application adopts PBFT consensus, and PBFT consensus does not allow the number of malicious nodes to exceed 1/3 of the total number of nodes, it is necessary to ensure that the proportion of malicious nodes in the blockchain system Δ is less than 1/3. If this condition is not met, q malicious nodes need to be removed from the blockchain system to ensure that Δ is less than 1/3. Among them, the proportion of malicious nodes in the blockchain system Δ is calculated as follows:

。

.

It should be understood that before sharding all the nodes in the blockchain system, it is necessary to determine whether the proportion of malicious nodes in all the nodes in the blockchain system is less than 1/3. If not, q malicious nodes need to be removed to ensure that the proportion of malicious nodes in all the nodes in the blockchain system is less than 1/3.

The blockchain node sharding method for node collaborative storage in the above-mentioned Internet of Vehicles environment solves the proof-of-work problem in all nodes in the blockchain system, and before the first h nodes that solve the proof-of-work problem are determined as member nodes in the directory committee, all nodes in the blockchain system are analyzed to determine malicious nodes in the blockchain system and the total number of malicious nodes; based on the total number of nodes in the blockchain system and the total number of malicious nodes in the blockchain system, it is determined whether the proportion of malicious nodes in the blockchain system is greater than one-third; when the proportion of malicious nodes in the blockchain system is greater than one-third, q malicious nodes are removed from the blockchain system to improve the security of the blockchain system.

It should be understood that, although the various steps in the flowchart of FIG. 1 are displayed in sequence according to the indication of the arrows, these steps are not necessarily executed in sequence according to the order indicated by the arrows. Unless there is a clear explanation in this article, the execution of these steps is not strictly limited in order, and these steps can be executed in other orders. Moreover, at least a part of the steps in FIG. 1 may include a plurality of sub-steps or a plurality of stages, and these sub-steps or stages are not necessarily executed at the same time, but can be executed at different times, and the execution order of these sub-steps or stages is not necessarily to be carried out in sequence, but can be executed in turn or alternately with other steps or at least a part of the sub-steps or stages of other steps.

The technical features of the above embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims (8)

1. A blockchain node sharding method for node collaborative storage in an Internet of Vehicles environment, characterized in that the method comprises: All nodes in the blockchain system solve the proof-of-work problem, and the first h nodes that solve the proof-of-work problem are determined as member nodes of the directory committee; Randomly select a leader node of the directory committee from each of the member nodes; Each of the member nodes runs the NSGA-II algorithm to obtain the best sharding result for each of the member nodes; Each of the member nodes sends its own best sharding result to the leader node; The leader node selects the best sharding result with the smallest communication delay difference from each best sharding result, and broadcasts the best sharding result with the smallest communication delay difference to other nodes in the directory committee; Other nodes in the directory committee confirm the signature based on the best shard result with the smallest communication delay difference received; When the leader node receives confirmation signatures from more than or equal to 2 h /3 nodes, the directory committee reaches a consensus and sharding is completed; When the leader node receives confirmation signatures from less than 2 h /3 nodes, it returns to the step of randomly selecting the leader node of the directory committee from each of the member nodes until the leader node receives confirmation signatures from more than or equal to 2 h /3 nodes, the directory committee reaches a consensus, the sharding is completed, and a sharding result list is generated; According to the sharding result list, the nodes in each shard are divided into cooperative groups, and a cooperative group division result list of each shard is determined. 2. The blockchain node sharding method for node collaborative storage in a connected vehicle environment according to claim 1, characterized in that before all nodes in the blockchain system solve the proof-of-work problem and the first h nodes that solve the proof-of-work problem first are determined as member nodes in the directory committee, it also includes: Analyze all nodes in the blockchain system to determine malicious nodes and the total number of malicious nodes in the blockchain system; Determining whether a proportion of malicious nodes in the blockchain system is greater than one-third based on the total number of nodes in the blockchain system and the total number of malicious nodes in the blockchain system; When the proportion of malicious nodes in the blockchain system is greater than one-third, removing q malicious nodes from the blockchain system; in,

,

is the number of malicious nodes that need to be removed, m is the number of malicious nodes in the blockchain system, N is the total number of nodes in the blockchain system, and Δ is the proportion of malicious nodes in the blockchain system. 3. The blockchain node sharding method for node collaborative storage in the Internet of Vehicles environment according to claim 1 is characterized in that the objective function of the NSGA-II algorithm is:

; in,

is the difference in the number of nodes between shards,

is the difference in the proportion of malicious nodes between shards,

is the communication delay difference between shards,

is the storage space difference between shards, Ω is the solution space of node partition, X is the best sharding result of member nodes, and R is the proportion of malicious nodes in the shard in the best sharding result. 4. The blockchain node sharding method for node collaborative storage in the Internet of Vehicles environment according to claim 3 is characterized in that the difference in the number of nodes between the shards

The calculation method is:

; in,

is the number of nodes in shard j , and h is the number of shards in the blockchain system. 5. The blockchain node sharding method for node collaborative storage in the Internet of Vehicles environment according to claim 4 is characterized in that the difference in the proportion of malicious nodes between the shards

The calculation method is:

;

; in,

is the ratio of malicious nodes in shard j , _and Ej is the number of malicious nodes in shard j . 6. The blockchain node sharding method for node collaborative storage in the Internet of Vehicles environment according to claim 5 is characterized in that the communication delay difference between the shards

The calculation method is:

; in,

is the difference in communication delay from all nodes in shard j to shard leader node u ,

is the communication delay from leader node u to node i , gj _is the total number of nodes in shard j ,

is the time when the shard leader node u receives the reply from node i ,

The time when the shard leader node u sends information to node i . 7. The blockchain node sharding method for node collaborative storage in the Internet of Vehicles environment according to claim 6 is characterized in that the storage space difference between the shards

The calculation method is:

; in,

is the storage space of the node in shard j , _and ci is the storage space size of node i . 8. The blockchain node sharding method for node collaborative storage in a connected vehicle environment according to claim 1, characterized in that the nodes in each shard are divided into collaborative groups according to the sharding result list, and the collaborative group division result list of each shard is determined, including: Remove the nodes whose available storage space in shard j is greater than _the storage space Fj required by shard j from the shard result list; The leader node of the directory committee broadcasts a notification of starting team formation; After receiving the notification to start teaming, the node in shard j immediately broadcasts the teaming request to other nodes in shard j ; When node i in shard j receives a message from node b agreeing to form a team, it calculates the available storage space of node i and node b . If the sum of the available storage space of node i and node b is greater than F _j , the team formation ends; If the sum of available storage space of node i and node b is less than or equal to F _j , continue to wait for teaming consent messages from other nodes until the sum of available storage space of node i and the nodes that agree to teaming is greater than F _j ; When all nodes of each shard in the shard result list have completed teaming or the sum of available storage space of the remaining unteamed nodes of each shard is less than F , the division of the collaboration groups of each shard is completed, and the remaining unteamed nodes of each shard will be used as candidate nodes of each shard.

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