A blockchain-based cooperative vehicle networking trust management method

Abstract

The application relates to the field of trust management in Internet of Vehicles, in particular to a cooperative Internet of Vehicles trust management method based on a block chain, which comprises the following steps: constructing an Internet of Vehicles system, which comprises vehicles, roadside units, a registration mechanism and a block chain; initiating a cooperative service request by a vehicle; receiving the cooperative service request by surrounding vehicles and selecting whether to respond; calculating a local trust value of the responding vehicles by the initiating vehicle, and selecting the responding vehicles to participate in cooperation according to the local trust value; after the initiating vehicle and the cooperative vehicles complete cooperation, the initiating vehicle performs trust rating on the cooperative vehicles and uploads the trust rating to the roadside units; after consensus is reached by the roadside units through a consensus algorithm, blocks are uploaded, and the updating of the trust information of the cooperative vehicles is completed; and the application can effectively reduce the false positive rate of malicious vehicle identification and improve the service cooperation success rate.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of trust management in Internet of Vehicles, and in particular to a collaborative Internet of Vehicles trust management method based on block chain. BACKGROUND

[0002] Internet of Vehicles (IoV) is a new type of self-organizing wireless network derived from Internet of Things, which mainly realizes network communication in multiple directions such as vehicle-to-vehicle, vehicle-to-road, vehicle-to-person, etc. Nowadays, with the intelligentization of vehicles, people have established a safe and efficient intelligent transportation system with the help of Internet of Vehicles, which has played a huge role in providing diversified services to users and reducing the occurrence of traffic accidents. However, with the deployment of a large number of sensors in vehicles and the increasing demand for vehicle services, information exchange between vehicles becomes frequent. At this time, vehicles are vulnerable to attacks from malicious nodes within the Internet of Vehicles during collaboration, thereby reducing the efficiency of the Internet of Vehicles and even threatening the safety of drivers.

[0003] Currently, trust management schemes and block chain technology are applied to Internet of Vehicles systems. Through the trust management scheme, the behavior of the vehicle is evaluated, and a trust value is given to the vehicle, so that only vehicles with a trust value greater than the trust threshold can participate in the collaboration of the Internet of Vehicles, thereby resisting attacks from malicious nodes within the Internet of Vehicles. However, most of the current trust management schemes use a binary trust evaluation method, which only classifies vehicle behavior into two levels: good and bad. At this time, the diversity of services in the Internet of Vehicles is not considered, i.e. different collaborative services have different requirements for the ability of collaborative vehicles. Due to the neglect of this feature of the Internet of Vehicles, some vehicles with low computing and storage capabilities are selected as collaborative vehicles to perform difficult tasks, which are marked as malicious vehicles when they fail to complete the collaborative services, i.e. the above scheme has a high false positive rate of malicious vehicle identification. In addition, managing the entity information and trust information of vehicles through block chain can reduce the storage pressure of the central server, ensure the consistency of data and realize the safe storage of data. However, the traditional proof of work algorithm requires nodes to calculate complex mathematical problems to compete for block power, which will generate a large amount of consensus delay and high resource consumption, and is not suitable for direct application to the Internet of Vehicles system.

[0004] In summary, the existing various trust management schemes based on block chain of the Internet of Vehicles have the problems of high false positive rate of malicious vehicle identification, inability to meet diversified services, and consensus algorithm not suitable for the current Internet of Vehicles environment, and there is still a lack of a trust management scheme for vehicle collaboration scenarios. SUMMARY

[0005] To solve the above problems, the present application provides a collaborative Internet of Vehicles trust management method based on block chain, comprising the following steps:

[0006] S1. Constructing a vehicle networking system, including vehicles, roadside units, a registration authority and a blockchain; each vehicle joining the vehicle networking system registers with the registration authority and obtains an initial trust level;

[0007] S2. Initiating a vehicle to initiate a cooperative service request, and surrounding vehicles receiving the cooperative service request and selecting whether to respond;

[0008] S3. The initiating vehicle calculates the local trust value of the responding vehicle, and selects the responding vehicle to participate in cooperation according to the local trust value;

[0009] S4. After the initiating vehicle and the cooperative vehicle complete the cooperation, the initiating vehicle performs trust rating on the cooperative vehicle and uploads it to the roadside unit;

[0010] S5. The roadside unit uploads the block after reaching a consensus through a consensus algorithm, and completes the update of the trust information of the cooperative vehicle.

[0011] The beneficial effects of the present application are:

[0012] The present application considers to construct a system model with four parts of vehicle, RSU, RA and blockchain; in view of the problems of high false positive rate of malicious vehicle identification, inability to meet diversified vehicle networking services, and the consensus algorithm not suitable for the current vehicle networking environment in the traditional trust management scheme, a cooperative vehicle networking trust management scheme based on blockchain is proposed.

[0013] Compared with the existing binary trust management scheme, the cooperative vehicle networking trust management scheme based on blockchain can effectively reduce the false positive rate of malicious vehicle identification, improve the success rate of service cooperation, and effectively improve the consensus efficiency compared with the traditional proof of work algorithm. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 The flowchart of the cooperative vehicle networking trust management scheme based on blockchain of the present application;

[0015] Figure 2 The system model diagram of the cooperative vehicle networking trust management scheme based on blockchain in the embodiment of the present application. DETAILED DESCRIPTION

[0016] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0017] The present application provides a cooperative vehicle networking trust management method based on blockchain, as shown inFigure 1 As shown, comprising the following steps:

[0018] S1. Constructing a vehicle networking system, which includes vehicles, road side units, a registration authority and a blockchain; each vehicle joining the vehicle networking system registers with the registration authority and obtains an initial trust level.

[0019] Specifically, the vehicle networking system constructed by the application comprises four parts as shown in the figure, including vehicles, road side units (RSU), a registration authority (RA) and a blockchain. Figure 2 As shown, comprising four parts of vehicles, road side units (RSU), a registration authority (RA) and a blockchain. Among them:

[0020] The vehicle is the main operating entity of the vehicle networking system; there are multiple vehicles in the vehicle networking system, and each vehicle is equipped with an on-board unit (OBU) and has certain computing and storage capabilities, can initiate a cooperative service request or provide cooperative services to surrounding vehicles, but due to the differences in the hardware and software performance of different vehicles, the comprehensive computing capabilities of different vehicles are different.

[0021] The RSU has strong computing and storage capabilities and has three functions in the vehicle networking system; 1) managing and coordinating road traffic in the jurisdictional area; 2) RSU as a consensus node in the blockchain, responsible for the maintenance of the blockchain, including block uploading, verification and trust information query and update; 3) responsible for forwarding the certificate verification request sent by the vehicle to the RA, and returning the verification result to the vehicle.

[0022] The blockchain is used as a distributed database to store the trust information of the vehicle, and each cooperative service is stored in the form of a transaction bill in the block.

[0023] The RA is a trusted authority in the vehicle networking, when the vehicle enters the vehicle networking system, it will first generate public and private keys used in the vehicle networking communication process, then the vehicle applies for registration to the RA, after completing the identity authentication, the RA will act as a certificate authority (CA) to create a public key certificate for the vehicle, which proves that the vehicle has a legal identity in the vehicle networking system, and then sends the public key certificate to the vehicle. In addition, as a trusted third party in the vehicle networking, the RA is responsible for allocating an initial trust level for the vehicle and transferring it to the RSU in the form of a transaction bill, and then recording it on the blockchain.

[0024] Specifically, in order to distinguish vehicles with different performance and behavior, the application sets n levels in the vehicle networking system based on the Dirichlet distribution, which is used to evaluate the trust degree of vehicle behavior; let the trust information of vehicle va up to the current qth cooperation be Among them represents the number of times that vehicle va obtains the i = 1, 2, …, n level evaluation up to the current qth cooperation; according to the trust information, the trust value of vehicle va at the specified level can be calculated, and the trust value is used as the probability that the behavior of vehicle va is at the specified level. The calculation formula of the trust value of vehicle va at the specified level is:

[0025]

[0026] represents the trust value of vehicle va at the specified trust level interval , and the specified trust level interval is the trust level interval required by the cooperative service that vehicle va participates in. r represents the level label set corresponding to the specified trust level interval, for example, the current cooperative service belongs to a three-level cooperative service, and vehicles with trust levels belonging to {n-1, n} are required to participate in cooperation, then the specified trust level interval l n-1 represents the specified level n-1, at this time r = {n-1, n}. represents the union set of probabilities related to the specified trust level interval , and p va (l i ) represents the probability that the trust level of vehicle va is l i . When , it indicates that vehicle va has the qualification to participate in this cooperative service, wherein Thre is a set trust threshold.

[0027] In order to distinguish different service types, the cooperative service of the vehicle is divided into three categories according to the importance of data in the present application:

[0028] (1) The first-level service is a service related to information entertainment, for example, multimedia resource sharing and the like.

[0029] (2) The second-level service is a service related to traffic efficiency, for example, road condition sharing and the like.

[0030] (3) The third-level service is a service related to traffic safety and user privacy, for example, danger warning and user location privacy-based service.

[0031] The trust level threshold of the respective designated cooperative vehicle in the three types of services is different, and in general, different levels of services need to be participated by vehicles of the designated trust level interval. The trust level threshold here refers to the lower limit of the level, for example, level n = 10, and the first level service must be participated by vehicles with a level greater than 3, and at this time the trust level threshold corresponding to the first level service is 3, that is, the proportion of the number of times that the cooperative vehicle obtains levels 4-10 to the total level is considered, and the proportion must be greater than the set trust threshold Thre to be a trusted vehicle.

[0032] Specifically, the process of each vehicle joining the Internet of Vehicles system to the registration authority for identity registration and obtaining an initial trust level in step S1 includes:

[0033] S11. The vehicle vi generates a public key and a private key used in the Internet of Vehicles communication process, and then sends an identity registration request information to the registration authority, wherein the identity registration request information includes the public key and the identity information ID of the vehicle vi vi ;

[0034] S12. The registration authority receives the identity registration request information, and then checks whether the identity information ID is revoked in the vehicle identity revocation list vi If yes, it indicates that the vehicle vi has been kicked out of the Internet of Vehicles system due to malicious behavior in the past Internet of Vehicles activities, and the registration authority refuses to provide the vehicle vi with a public key certificate to join the Internet of Vehicles system; if not, step S13 is executed;

[0035] Among them, the vehicle identity revocation list is used to store malicious vehicles that have been kicked out of the Internet of Vehicles system due to multiple malicious behaviors, and since the vehicle entity identity cannot be forged in general, such malicious vehicles cannot join the Internet of Vehicles by re-registering their identity.

[0036] S13. The registration authority saves the identity information of the vehicle vi and issues a public key certificate for the vehicle vi, and transfers the initial trust level of the vehicle vi to the roadside unit in the form of a transaction bill, which is recorded on the blockchain by the roadside unit. The number of times that the vehicle vi obtains the i = 1, 2, …, n level trust evaluation before the first cooperation; in theory, the vehicle vi has not participated in cooperation when it first joins the Internet of Vehicles, so the cooperation times q = 0, but in this way the trust value of the vehicle will always be 0 and cannot participate in cooperation, in order to ensure that the vehicle vi has the qualification to participate in cooperation when it first joins the Internet of Vehicles, the registration authority allocates n represents the highest level.

[0037] S2. The initiating vehicle initiates a cooperative service request, and the surrounding vehicles receive the cooperative service request and select whether to respond.

[0038] ​Specifically, a vehicle group v corresponding to the initiating vehicle va is defined as v = {v1, v2,..., vn}, where n represents the number of vehicles; the vehicle group v is composed of the initiating vehicle va and all vehicles within the communication range of the initiating vehicle va; in step S2, the initiating vehicle va initiates a cooperative service request, and the specific process of the surrounding vehicles receiving the cooperative service request and selecting whether to respond includes: M}, M represents the number of vehicles; the vehicle group v is composed of the initiating vehicle va and all vehicles within the communication range of the initiating vehicle va; in step S2, the initiating vehicle va initiates a cooperative service request, and the specific process of the surrounding vehicles receiving the cooperative service request and selecting whether to respond includes:

[0039] S21. The initiating vehicle va broadcasts its own cooperative service request to the surrounding vehicles, and the cooperative service request includes the type of cooperative service to be performed and its own public key certificate;

[0040] S22. After the vehicle vb∈v receives the cooperative service request, it decides whether to participate in cooperation according to its own conditions and the cooperative service type of the initiating vehicle va, and if it decides to participate in cooperation, it performs step S23; specifically, when the surrounding vehicles receive the cooperative service request, they have the right to refuse cooperation, and in general, the surrounding vehicles will consider whether to cooperate according to the type of cooperative service initiated by the initiating vehicle, for example, when the surrounding vehicles find that the required computing power or trust level of this cooperative service is higher, and the hardware of the surrounding vehicles cannot meet the requirements, the surrounding vehicles can directly refuse to participate in cooperation.

[0041] S23. The vehicle vb sends a certificate authenticity verification request to the roadside unit, and the certificate authenticity verification request includes the public key certificate of the initiating vehicle va; the roadside unit receives the certificate authenticity verification request and forwards it to the registration authority for verification;

[0042] S24. The registration authority receives the certificate authenticity verification request and checks the public key certificate of the initiating vehicle va, and verifies whether the identity information ID corresponding to the public key certificate of the initiating vehicle va is revoked, if yes, step S25 is performed, if not, step S26 is performed; va

[0043] S25. The roadside unit returns a verification failure message to the vehicle vb; the vehicle vb refuses to participate in cooperation and does not respond to the initiating vehicle va;

[0044] S26. The roadside unit returns a verification success message to the vehicle vb; the vehicle vb responds to the initiating vehicle va, and sends a response message to the initiating vehicle, and the response message includes the communication distance D between the vehicle vb and the initiating vehicle va, the public key certificate of the vehicle vb, and the transaction billing information after the vehicle vb last participated in cooperation. a,b

[0045] S3. The initiating vehicle calculates the local trust value of the responding vehicle, and selects the responding vehicle to participate in cooperation according to the local trust value.

[0046] ​​Specifically, if the vehicle vb responds to the initiating vehicle va, the initiating vehicle va calculates the local trust value of the vehicle vb according to the response information sent by the vehicle vb, including:

[0047] S31. The initiating vehicle va sends a verification request to the roadside unit, the verification request including the public key certificate of the vehicle vb and the transaction billing information of the vehicle vb after the last participation in cooperation;

[0048] S32. The roadside unit forwards the verification request to the registration authority, and the registration authority checks the public key certificate of the vehicle vb, verifies the identity information ID corresponding to the public key certificate of the vehicle vb vb Whether it is revoked, if so, return the verification failure information to the initiating vehicle va through the roadside unit; if not, execute step S33;

[0049] S33. The registration authority returns the verification success information and the computing capability C vb of the vehicle vb to the roadside unit, and the roadside unit queries the trust information of the vehicle vb after the last participation in cooperation in the blockchain according to the transaction billing information of the vehicle vb after the last participation in cooperation; The roadside unit forwards the verification success information, the computing capability C vb of the vehicle vb and the trust information of the vehicle vb after the last participation in cooperation to the initiating vehicle va together;

[0050] S34. The initiating vehicle va calculates the local trust value of the vehicle vb according to the computing capability C vb of the vehicle vb and the trust information after the last participation in cooperation ; judges whether the local trust value of the vehicle vb is greater than or equal to the trust threshold Thre1, if so, agrees that the vehicle vb participates in cooperation, and the initiating vehicle va starts interaction with the vehicle vb; if not, refuses the vehicle vb to participate in cooperation.

[0051] Specifically, the step S34 calculates the local trust of the vehicle vb according to the computing capability C vb of the vehicle vb and the trust information after the last participation in cooperation , including:

[0052] S341. Calculate the current behavior evaluation value E a,b of the vehicle vb, expressed as:

[0053] E a,b =α1·C vb +α2·(1-P loss )+α3·F a,b

[0054]

[0055] wherein, α1, α2, α3 represent weight factors; vehicle vb computing capability C vb For vehicle vb at the time of registration with RA, RA evaluates the comprehensive performance of vehicle vb by identifying the hardware and software performance of vehicle OBU, and the result is 0 < C vb <1; P loss represents the propagation delay, D a,b represents the communication distance between vehicle vb and initiating vehicle va, D max represents the maximum communication distance to ensure normal communication between vehicles, then D a,b ≤ D max and 0 < P loss ≤ 1; F a,b represents familiarity, m represents the number of common neighbors of vehicle vb and initiating vehicle va, and j represents the number of all neighbors of initiating vehicle va; wherein the neighbors of initiating vehicle va refer to surrounding vehicles that have cooperated with vehicle va, and the neighbors of vehicle vb refer to surrounding vehicles that have cooperated with vehicle vb, and it should be noted that the surrounding vehicles herein are within the communication range of initiating vehicle va, and the familiarity satisfies 0 ≤ F a,b ≤ 1.

[0056] S342. The common neighbors of initiating vehicle va and cooperative vehicle vb (i.e. surrounding vehicles that have interacted with both initiating vehicle va and cooperative vehicle vb) are used to calculate the neighbor recommendation value E k,b of vehicle vb, which is represented as:

[0057]

[0058] wherein, θ a,k represents a confidence factor, i.e. the trust degree of initiating vehicle va to its neighbor vk; represents the trust value of neighbor vk in the specified trust level interval represents the sum of trust values of all neighbors in the specified trust level interval; NDT k,b represents the recommendation value of neighbor vk to vehicle vb; s k,b represents the number of successful interactions between neighbor vk and vehicle vb, u k,b represents the number of failed interactions between neighbor vk and vehicle vb; the higher the successful interaction rate between neighbor and cooperative vehicle, the higher the recommendation degree to the cooperative vehicle.

[0059] S343. The local trust of vehicle vb is calculated which is represented as:

[0060]

[0061] β1+β2=1

[0062] ​Wherein, β1, β2 are weight factors, and β1+β2=1, the application introduces a weight parameter here for adjustment, dynamically adjusts the weight ratio of recommended trust according to the number of common neighbors, r represents an adjustment factor, and m represents the number of common neighbors of vehicle va and vehicle vb;

[0063] S344. The local trust is obtained by the local trust rating Indicates rounding up, combined with the trust information of vehicle vb after the last time participating in cooperation To obtain the local trust value. Specifically,

[0064] q∈{1,2,…,n}, then vehicle va temporarily adds one to the number of times vehicle vb obtains the rth level, and then calculates the trust value of vehicle va at the level specified by the cooperative service published by vehicle va As the local trust value.

[0065] S4. After the initiating vehicle and the cooperative vehicle complete the cooperation, the initiating vehicle performs trust rating on the cooperative vehicle and uploads it to the roadside unit.

[0066] Specifically, step S4 initiates vehicle va to perform trust rating on vehicle vb participating in cooperation, including:

[0067] S41. Calculate the data packet delivery rate PDR of the cooperation process a,b , which is expressed as:

[0068]

[0069] Wherein, s a,b Indicates the number of successful interactions between initiating vehicle va and vehicle vb, u a,b Indicates the number of failed interactions between initiating vehicle va and vehicle vb; the data packet delivery rate can be regarded as the most intuitive evaluation of interaction quality.

[0070] S42. Calculate the time delay l of the cooperation process g , which is expressed as:

[0071]

[0072] Wherein, t q Indicates the start time of the cooperative service, t r Indicates the end time of the cooperative service, trans(△t r ) indicates the expected propagation delay estimated by vehicle va according to experience, (t r -t q )-trans(△t r ) can be regarded as the hesitation time, and △t mrepresents the maximum hesitation time; the time delay represents the immediacy of the response of the cooperative vehicle in the whole process of vehicle interaction.

[0073] S43. Calculate the interaction quality of the cooperation process is represented as:

[0074]

[0075] The interaction quality represents the overall performance of the cooperative vehicle in the cooperation process. The higher the data packet delivery rate of the cooperative vehicle and the lower the time delay, the better the interaction quality provided and the higher the evaluation level obtained. When the data packet delivery rate satisfies PDR a,b ≥ Thre2 and the time delay satisfies (t r -t q )-trans (Δt r ) ≤ Δt m , it indicates that this cooperation is successful, where Thre2 is a threshold for determining whether the data is successfully delivered.

[0076] S44. Calculate the trust evaluation result is represented as:

[0077]

[0078] where W a,b represents a weight parameter; the behavior of the vehicle in the whole cooperation process is finally evaluated after the vehicle cooperation interaction. Due to the diversification of the vehicle cooperation service type, different evaluation standards are needed for different services, so the weight parameter W a,b is designed in the present application to measure the weight of the two evaluations, specifically:

[0079]

[0080] S45. Obtain the final trust rating of the vehicle va to the vehicle vb according to the trust evaluation result Specifically, the initiating vehicle va uploads the trust rating i of the cooperative vehicle vb in this cooperation service to the RSU, and the RSU updates the trust information of the cooperative vehicle vb, including:

[0081] The number of times that the vehicle vb obtains the i-th level of trust evaluation by the end of the current q-th cooperation is updated as:

[0082]

[0083] ε i = λ (n + 1-i)

[0084] where ε i ​represents an adjustment parameter, λ represents an adjustment factor, and n represents the highest rank number;

[0085] updating the trust information of the vehicle vb

[0086] In each trust information update, only the rank number obtained by the cooperative vehicle is updated, and the remaining rank numbers remain the results updated during the last cooperation, that is, and so on.

[0087] S5. After the roadside unit reaches a consensus through the consensus algorithm, the block is uploaded, and the updating of the trust information of the cooperative vehicle is completed.

[0088] Specifically, step S5 includes:

[0089] S51. The hash value of each roadside unit is calculated, and the calculation formula is:

[0090] RSU hash = Hash (ID rsu || prehash || timestamp || nonce)

[0091] wherein RSU hash represents the hash value of the roadside unit, Hash() represents a hash function, ID rsu represents the number of the roadside unit, prehash represents the hash value of the last block in the current blockchain, timestamp represents a time stamp, and nonce represents a random number; all nodes need to keep calculating the hash value until a node calculates a hash value meeting the condition, and competes for the block right;

[0092] S52. In order to make the result meet the set hash threshold value, each roadside unit continuously adjusts the random number for updating the hash value until the hash value of one roadside unit is less than the hash threshold value T j , and the roadside unit is taken as a miner node; the calculation formula of the hash threshold value T J is:

[0093]

[0094] N J = N m -param-Dap

[0095] wherein N J represents a hash threshold adjustment index, N m represents the number of bits of the hash value, which is determined by the selected hash algorithm, and the present application selects the SHA-256 algorithm, so that N m= 256; param represents an adjustment factor for controlling the hash threshold value, and Dap represents a difficulty value adjustment parameter, which is used to adjust the difficulty level of the system as a whole, and controls the speed of block accounting. The hash threshold value is adjusted according to the number of collaborative services and the service level in the current area, and is specifically:

[0096] param = e -ωδ+θ

[0097]

[0098] ω represents a regulation factor of the hash threshold value, δ is a task priority index, θ is a hash threshold regulation parameter, num J is the total number of services with a service level J in the current area; due to the presence of the task priority index, the difficulty of block generation of the RSU with more collaborative services and a high service level in the current area is reduced, the node with the block generation right can be decided faster, the rapid uploading and updating of the vehicle trust level are ensured, and meanwhile, the consumption of a large amount of computing resources by other blocks for competing for the block generation right is avoided, and the operation efficiency of the block chain is improved.

[0099] S53. The miner node generates a transaction bill according to the received updated trust information, assembles the transaction bill into a new block for broadcasting, the remaining roadside units return confirmation information after verifying the validity of the new block, and the miner node adds the new block to the block chain after receiving the confirmation information from all the remaining roadside units, and then sends the transaction bill to the collaborative vehicle through the roadside unit.

[0100] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "setting", "connecting", "fixing", "rotating" and the like should be understood in a broad sense, for example, can be fixedly connected, or can be detachably connected, or can be integrated; can be mechanically connected, or can be electrically connected; can be directly connected, or can be indirectly connected through an intermediate medium; can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise explicitly limited, the above-mentioned terms in the present application can be understood according to the specific meaning of the above-mentioned terms in the present application by those skilled in the art.

[0101] Although the embodiments of the present application have been shown and described, it can be understood by those skilled in the art that various changes, modifications, replacements and variations can be made to the embodiments without departing from the principles and spirits of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1.A blockchain-based cooperative trust management method for V2X, characterized in that, Comprise the following steps: S1. Constructing a vehicle networking system, comprising vehicles, roadside units, a registration authority and a blockchain; each vehicle joining the vehicle networking system registers with the registration authority and obtains an initial trust level; S2. Initiating a vehicle initiating a cooperative service request, surrounding vehicles receiving the cooperative service request and selecting whether to respond; S3. The initiating vehicle calculates the local trust value of the responding vehicle, and selects the responding vehicle to participate in cooperation according to the local trust value; S4. After the initiating vehicle completes cooperation with the cooperative vehicle, the initiating vehicle performs trust rating on the cooperative vehicle and uploads it to the roadside unit; Step S4, the initiating vehicle va performs trust rating on the vehicle vb participating in cooperation, comprising: S41. Calculate the data packet delivery rate PDR of the collaboration process a,b is represented as: wherein s a,b represents the number of successful interactions between the initiating vehicle vaand the vehicle vb, u a,b represents the number of failed interactions between the initiating vehicle vaand the vehicle vb; S42. Calculate the time delay l of the cooperation process g is expressed as: where t q represents the start time of the collaboration service, t r represents the end time of the collaboration service, trans(△t r ) represents the expected propagation delay, △t m represents the maximum hesitation time; S43. Calculate interaction quality of the collaboration process is represented as: S44. Calculate the trust evaluation result is expressed as: wherein W a,b represents a weight parameter; S45. obtaining a final trust rating of the initiating vehicle va for the vehicle vb according to the trust evaluation result S5. The roadside unit uploads the block after reaching a consensus through a consensus algorithm, and completes the update of the trust information of the cooperative vehicle. 2.The blockchain-based cooperative trust management method for V2X according to claim 1, wherein, In the vehicle networking system, each vehicle is equipped with a vehicle-mounted unit for initiating a cooperative service request or providing a cooperative service; wherein the cooperative services are divided into three categories according to the importance of the data: first-level service, second-level service and third-level service; meanwhile, n levels are set in the vehicle networking system to evaluate the trustworthiness of vehicle behavior. 3.The blockchain-based cooperative trust management method for V2X according to claim 1, wherein, In step S1, the process of each vehicle joining the vehicle networking system to the registration authority for identity registration and obtaining an initial trust level comprises: S11. The vehicle vi generates a public key and a private key used in the vehicle-to-everything communication process, and then sends an identity registration request information including the public key and identity information ID of the vehicle vi to the registration authority vi ; S12. The registration authority receives the identity registration request information, and then checks the identity information ID in the vehicle identity revocation list vi whether the vehicle vi is revoked, if yes, the vehicle vi is rejected to join the Internet of Vehicles system, if not, step S13 is performed.​ S13. The registration authority saves the identity information of the vehicle vi and issues a public key certificate for the vehicle vi, and at the same time, assigns initial trust information to the vehicle vi and forwards the initial trust information of the vehicle vi to the roadside unit in the form of a transaction bill, which is recorded on the blockchain by the roadside unit; represents the number of times the vehicle vi obtains the i = 1, 2, …, n level trust evaluation before the initial cooperation; in order to ensure that the vehicle vi has the qualification to participate in the cooperation when it first joins the Internet of Vehicles, the registration authority assigns n represents the highest level number. 4.The blockchain-based cooperative trust management method for V2X according to claim 1, wherein, Define the vehicle group v corresponding to the initiating vehicle va = {v1,v2,...,v M }, M represents the number of vehicles; the vehicle group v consists of the initiating vehicle va and all vehicles within the communication range of the initiating vehicle va; in step S2, the initiating vehicle va initiates a collaborative service request, and the surrounding vehicles receive the collaborative service request and choose whether to respond. The specific process includes: S21. The initiating vehicle va broadcasts its cooperative service request to surrounding vehicles, the cooperative service request comprising a cooperative service type and a public key certificate; S22. After the vehicle vb∈v receives the cooperative service request, it decides whether to participate in cooperation according to its own conditions and the cooperative service type of the initiating vehicle va, if it decides to participate in cooperation, it executes step S23; S23. The vehicle vb sends a certificate authenticity verification request to the roadside unit, the certificate authenticity verification request comprising the public key certificate of the initiating vehicle va; the roadside unit receives the certificate authenticity verification request and forwards it to the registration authority; S24. The registration authority receives the certificate authenticity verification request and looks up the public key certificate of the initiating vehicle va, verifies the identity information ID corresponding to the public key certificate of the initiating vehicle va va whether it is revoked, if so, step S25 is performed, if not, step S26 is performed; S25. The roadside unit returns a verification failure message to the vehicle vb; the vehicle vb refuses to participate in cooperation and does not respond to the initiating vehicle va; S26. Return the verification success information to the vehicle vb through the roadside unit; the vehicle vb initiates a response to the vehicle va, and sends the response information to the initiating vehicle, wherein the response information comprises a communication distance D between the vehicle vb and the initiating vehicle va, a public key certificate of the vehicle vb, and transaction billing information after the vehicle vb last participates in the cooperation. a,b , the vehicle vb initiates a response to the vehicle va, and sends the response information to the initiating vehicle, wherein the response information comprises a communication distance D between the vehicle vb and the initiating vehicle va, a public key certificate of the vehicle vb, and transaction billing information after the vehicle vb last participates in the cooperation. 5.The blockchain-based cooperative trust management method for V2X according to claim 1, wherein, If the vehicle vb responds to the initiating vehicle va, the initiating vehicle va calculates the local trust value of the vehicle vb according to the response information sent by the vehicle vb, comprising: S31. The initiating vehicle va sends a verification request to the roadside unit, the verification request comprising the public key certificate of the vehicle vb and the transaction bill information after the vehicle vb last participated in cooperation; S32. The road side unit forwards the verification request to the registration authority, which checks the public key certificate of the vehicle vb and verifies the identity information ID corresponding to the public key certificate of the vehicle vb vb whether it is revoked, if yes, returns a verification failure information to the initiating vehicle va through the road side unit; if not, executes step S33; S33. The registration authority returns the verification success information and the vehicle vb computing capability C to the roadside unit vb The roadside unit queries the trust information of the vehicle vb after the last time of participating in cooperation in the blockchain according to the transaction bill information of the vehicle vb after the last time of participating in cooperation The roadside unit forwards the verification success information, the vehicle vb computing capability C vb And the trust information of the vehicle vb after the last time of participating in cooperation To the initiating vehicle va together; S34. Initiating vehicle va calculates capability C according to vehicle vb vb Trust information after last participation in cooperation Calculating local trust value of vehicle vb; judging whether the local trust value of vehicle vb is greater than or equal to trust threshold Thre1, if yes, agreeing that vehicle vb participates in cooperation, and initiating vehicle va to start interaction with vehicle vb; if not, refusing vehicle vb to participate in cooperation. 6.The blockchain-based cooperative trust management method for V2X according to claim 5, wherein, Step S34 initiates the vehicle va to compute the capability C from the vehicle vb vb and trust information from the last participation in the collaboration computing the local trust of the vehicle vb, comprising: S341. Calculate a current behavior evaluation value E of the vehicle vb a,b is expressed as: E a,b = a1 · C vb + a2 · (1 - P loss ) + a3 · F a,b wherein a1, a2, a3 represent weight factors; P loss denotes the propagation delay, D a,b denotes the communication distance between vehicle vb and the initiating vehicle va, D max denotes the maximum communication distance to ensure normal communication between vehicles; F a,b denotes the familiarity, m denotes the number of common neighbors of vehicle va and vehicle vb, j denotes the number of neighbors of vehicle va; S342. Calculate the neighbor recommendation value E of the vehicle vb k,b is represented as: k≠a and k≠b k≠a and k≠b where θ a,k denotes a confidence factor, denotes the trust value of neighbor vk in the specified trust level interval NDT k,b denotes the recommendation value of neighbor vk to vehicle vb; s k,b denotes the number of successful interactions of neighbor vk with vehicle vb, u k,b denotes the number of failed interactions of neighbor vk with vehicle vb; S343. Calculate a local trust of the vehicle vb is represented as: β1+β2＝1 Wherein, β1, β2 are weight factors, and r represents an adjustment factor; S344. obtaining a local trust rating by local trust in combination with trust information from the last participation of the vehicle vb in the cooperation obtaining a local trust value. 7.The blockchain-based cooperative trust management method for V2X according to claim 1, wherein, After the initiating vehicle va uploads the trust rating i of the cooperative vehicle vb in this cooperative service to the roadside unit, the roadside unit updates the trust information of the cooperative vehicle vb, comprising: the number of times the vehicle vb obtains the trust evaluation of the i-th level until the current q-th cooperation is: ε i = λ(n + 1 - i) wherein ε i denotes an adjustment parameter, λ denotes an adjustment factor, and n denotes the highest rank number; Updating trust information of a vehicle vb 8.The blockchain-based cooperative trust management method for V2X according to claim 1, wherein, Step S5 specifically comprises: S51. Calculate the hash value of each roadside unit, the calculation formula is: RSU hash = Hash(ID rsu || prehash || timestamp || nonce) wherein RSU hash represents the hash value of the roadside unit, Hash() represents a hash function, ID rsu represents the number of the roadside unit, prehash represents the hash value of the previous block in the blockchain, timestamp represents a time stamp, and nonce represents a random number; S52. Each roadside unit continuously adjusts the random number for updating the hash value until there is a roadside unit whose hash value is less than the hash threshold value T J , and the roadside unit is taken as a miner node; the calculation formula of the hash threshold value T J is: N J = N m -param-Dap param=e -ωδ+θ wherein N J represents a hash threshold adjustment index, N m represents the number of bits of the hash value, param represents an adjustment factor controlling the hash threshold, Dap represents a difficulty value adjustment parameter; ω represents a hash threshold regulation factor, δ is a task priority index, θ is a hash threshold regulation parameter, num J is the total number of services of the current regional service level J. S53. The miner node generates a transaction bill according to the received updated trust information, assembles the transaction bill into a new block for broadcast, the remaining roadside units verify the validity of the new block and return confirmation information, the miner node receives confirmation information from all the remaining roadside units, adds the new block to the blockchain, and then sends the transaction bill to the cooperative vehicle through the roadside unit.

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