WO2020258060A2

WO2020258060A2 - Blockchain-based privacy protection trust model for internet of vehicles

Info

Publication number: WO2020258060A2
Application number: PCT/CN2019/092883
Authority: WO
Inventors: 黄海平; 马子洋; 肖甫; 刘星晨; 戴华; 王汝传; 孙翔; 朱鹏
Original assignee: 南京邮电大学
Priority date: 2019-06-25
Filing date: 2019-06-26
Publication date: 2020-12-30
Also published as: CN110300107A; WO2020258060A3; CN110300107B

Abstract

Provided in the present invention is a blockchain-based privacy protection trust model for the Internet of Vehicles. Vehicles on a road generate and broadcast messages by means of a vehicular ad-hoc network in order to share traffic information of the surroundings to improve traffic efficiency and safety. However, because of the untrustworthy network environment of vehicular ad-hoc networks, vehicles can easily expose private information and cannot determine whether a received message is reliable. In the present invention, a vehicle is caused to send a message anonymously by means of ring signature technology, preventing the vehicle from being tracked by a malicious vehicle. Messages sent by vehicles are evaluated and filtered by means of a blockchain technology-based credibility evaluation mechanism, filtering out fake information therein. On the basis of the features of the blockchain itself, it is ensured that vehicle credibility will not be subject to malicious tampering, and real-time synchronous updating of vehicle credibility is made possible, further improving the security and usability of vehicular ad-hoc networks.

Description

A blockchain-based privacy protection trust model for the Internet of Vehicles

Technical field

The invention relates to the technical fields of car networking communication security, and in particular to a blockchain-based car networking privacy protection trust model.

Background technique

In recent years, VANETs have been regarded as the infrastructure of intelligent transportation systems, which can improve traffic efficiency and ensure the safety of vehicles and pedestrians. In order to promote cooperation between vehicles and share valuable driving information, two kinds of communication are established in the vehicle-mounted ad hoc network, namely vehicle-to-vehicle (V2V) communication and vehicle-to-infrastructure (V2I) communication. Through the dedicated short-range communication radio, nearby vehicles exchange information with V2V and can directly communicate with the roadside unit (RSU) in the V2I.

However, due to the fast moving speed of vehicle nodes in the vehicle ad hoc network and the short network connection time between nodes (high mobility and high volatility), the network topology changes frequently and the communication time between nodes is limited. These characteristics make the vehicle ad hoc network The net is vulnerable to various attacks. Although the main security services of the vehicular ad hoc network have been deeply studied in other fields, the research results in these fields can provide a secure communication channel to resist external attacks, but the trust management and privacy issues have not been well resolved.

The internal attackers in the vehicular ad hoc network can not only obtain private information by analyzing all broadcast messages in the network and easily track the location of other vehicles, but also can forge messages, causing major safety risks to road traffic. The trust management system can help the vehicle judge whether the received message is credible. The existing trust management system is usually divided into two types: centralized and decentralized. In a centralized system, all execution processes are carried out on the central server, which may cause serious delays and is not suitable for the high service quality requirements of the vehicle-mounted ad hoc network. In a decentralized system, the trust management system is usually deployed in the roadside unit (RSU), but the RSU may be maliciously attacked. The attacker will wantonly tamper with the vehicle reputation information stored in the RSU, so how Effective provision of trust management services has also become an important issue that needs to be resolved.

Summary of the invention

The present invention proposes a blockchain-based privacy protection trust model for the Internet of Vehicles to solve the privacy and trust issues between vehicles in an untrusted environment of the Internet of Vehicles. The present invention adopts ring signature technology and pseudonym (public key address) to hide the ID of communication between vehicle users to ensure privacy between vehicles. Evaluate the messages in the Internet of Vehicles through the reputation evaluation mechanism to filter forgery and malicious messages, and use blockchain technology to strengthen the message integrity and tamper resistance of the trust management system, reducing the malicious impact of malicious vehicles on traffic safety .

A blockchain-based privacy protection trust model for the Internet of Vehicles includes the following steps:

Step 1. The trusted authority center TA selects E _k (x) as a symmetric encryption protocol that uses a key k to encrypt x, and the public key and private key of the symmetric encryption protocol are the same key, and at the same time selects or generates public parameters or objects;

Step 2: When the vehicle joins the vehicle ad hoc network for the first time, the reputation score is initialized; at the same time, the vehicle user uses his real identity ID to obtain his public-private key pair and pseudonym, that is, the public key address, from the trusted authority center TA;

Step 3. When a vehicle witnesses a traffic incident on the road, he will share this traffic message msg with other vehicles in the on-board ad hoc network, and call this vehicle the initiating vehicle; others around are witnesses to help prove The vehicle with the authenticity of the msg message is called the corroborating vehicle;

Step 4. After the initiating vehicle witnesses the traffic incident, in order to obtain feedback from other supporting vehicles on the message, and to ensure the reliability of the message, a request message RQP is generated;

Step 5. Through the ring signature, the initiating vehicle will be broadcast anonymously; after the supporting vehicle receives the information of the initiating vehicle, it will return the supporting message RPP and the cipher text information EM of whether the generated message is reliable, that is, whether the supporting vehicle is reliable or not Encrypted data of the message;

Step 6. After the initiating vehicle receives enough supporting information (signature threshold is t), assume S={ID _r-t+1 ,...,ID _r }, and package these messages to generate aggregated message AGP ; The initiating vehicle sends AGP=(<γ ₁ , m ₁ , α ₁ , β ₁ >,..., <γ _r , m _r , α _r , β _r >, msg, t, S∪S') through the secure channel To the adjacent roadside unit (RSU);

Step 7. After the RSU receives the AGP of the initiating vehicle, it does the following:

Step 7-1, obtain (<ID ₁ , γ ₁ , m ₁ , α ₁ , β ₁ >,..., <ID _r , γ _r , m _r , α _r , β _r >, msg, t) from AGP;

Step 7-2, for each ID _i , calculate

(h _j is the content of the jth bit of H(ID), Y _j is

The content of bit j);

Step 7-3, for each ID _i , calculate m _i ·g=H(α _i )·PK+α _i β _i , if any set of <m _i , α _i , β _i > is not satisfied, then the ring signature Verification failed;

Step 7-4, calculate k=H(msg) and EM=E _k (z). If EM=E _k (1), then z=1; if EM=E _k (-1), then z=-1;

Step 8. RSU queries the reputation scores of the initiating vehicles and supporting vehicles in the blockchain maintained by the RSU. Based on the reputation scores, the RSU will calculate the reliability of the message msg;

Step 9. When the message msg calculation result is reliable, the RSU first broadcasts the message to other vehicles (called vehicles) within its communication range and increases the reputation score R _new for the initiating vehicle and the supporting vehicle with the reply information "1" =(1-s)R+R, R _new is the new vehicle reputation score after the update, and R is the vehicle reputation score before the update. When the message msg calculation result is unreliable, the RSU penalizes the initiating vehicle and the supporting vehicle whose reply information is "-1" to reduce the reputation score R _new =(1-t)R+R. Where 0≤s≤1, -1≤t≤0. RSU packs the updated information of the vehicle reputation score into blocks and broadcasts it to the consensus network;

Step 10: The RSU responsible for the consensus work in the vehicle ad hoc network carries out a consensus on the update of the vehicle reputation score. After the consensus phase is over, all RSUs record the new vehicle reputation score in the blockchain ledger maintained by themselves.

Further, the public parameters or objects selected or generated in step 1 are as follows:

Step 1-1, select G as the additive group whose point is on the elliptic curve, q is the order of G, and g is the generator of G;

Step 1-2, select H as the hash function, H: {0,1}*→{0,1} ⁿ , that is, map an arbitrary length of 0,1 data set to a 0,1 data set of length n;

Step 1-3, generate

Means from

(Set of integers of arbitrary length with order q) Assign values to X ₁ ,..., X _n , Y _i =X _i *g, X _i ∈(X ₁ ,..., X _n ) by randomly selecting elements in the set;

Step 1-4, generate

To manage the private key vector,

To manage the public key vector.

Further, the step 2 specifically includes the following sub-steps:

Step 2-1, TA initializes the reputation score of the vehicle as R (0≤R≤1);

Step 2-2, TA generates the on-board user private key according to the real ID

Is the content of the i-th bit of H(ID), i=1,...n), and the vehicle user public key

The public key address addrpk=H(sk _ID ); the private key of the vehicle user is stored in the TA and is not publicly disclosed; the public and private key pair of the vehicle user is used in the signature, and the public key address, namely the pseudonym, is used in the blockchain;

Step 2-3, all roadside units (RSU) in the vehicle ad hoc network store the pseudonym addrpk and reputation score R of the vehicle into the blockchain maintained by themselves.

Further, in the step 4, specifically, to ensure the reliability of the message, perform the following operations to generate the request message RQP:

Step 4-1, generate a ring signature to protect the privacy of the initiating vehicle. Arbitrary integers r and t; r is the length of the ring signature, and t is the length of the signature threshold;

Step 4-2, arbitrarily select rt IDs from the ID list set, expressed as S'={ID ₁ ,..., ID _rt };

Step 4-3, for each ID _i ∈S', calculate

h _j is the content of the jth bit of H(ID), and Y _j is

The content of the j-th bit;

Step 4-4, for each ID _i ∈S', generate

Means from

A set of integers of arbitrary length with order q, randomly selected elements in the set are assigned to γ _i , and γ _{i is} used as the index of ID _i ;

Step 4-5, calculate the EC-Elgamal signature for each ID _i ∈S'; generate a _i ,

Means from

A set of integers of arbitrary length with order q, randomly select elements in the set and assign values to a _i and b _i , calculate

α _i ＝a _i ·g+b _i ·PK _i

β _i ＝-b _i ^-1 H(α _i )

m _i = a _i · β _i.

Steps 4-6, define Ω=({ID ₁ ,..., ID _rt }, {γ ₁ ,...,γ _rt }, {m ₁ ,..., m _rt }), RQP=(msg, r, t, Ω ).

Further, the step 5 specifically includes the following sub-steps:

Step 5-1, supporting the vehicle to obtain the information (msg, r, t, Ω) in the request message RQP;

Step 5-2, generate

And γ does not belong to the set {γ ₁ ,..., γ _rt }, as the ID index of the supporting vehicle;

Step 5-3, generate

Calculate α=c·g and β=(m-sk _ID H(α))c ^-1 ;

Step 5-4, generate a supporting message RPP=(s,m,(α,β),ID), and send the RPP to the initiating vehicle;

Step 5-5: Calculate k=H(msg), and generate variable z to represent whether the vehicle considers the message msg to be reliable. If z=1, it is considered reliable, otherwise -1 is unreliable. EM=E _k (z), send EM to RSU.

Further, the reliability calculation process in step 8 is as follows:

Step 8-1, calculate the total reputation score;

among them

Indicates the average credit score value of the supporting vehicles with a response of "1", z _i and M respectively represent the credit value and number of supporting vehicles with a response of "1".

Indicates the average credit score value of the supporting vehicles with a response of "-1", z _j and N respectively represent the credit value and number of supporting vehicles with a response of "-1";

Step 8-2, determine the weight;

Where w _i and w _j represent the weight of the supporting vehicle;

Step 8-3, weighting calculation;

among them

Respectively indicate the weighted average of the credibility scores of supporting vehicles with the answers "1" and "-1";

Step 8-4, judge the reliability of the message msg;

among them

If the calculation result meets the conditions in the above formula, the message msg is considered reliable, and minRe is the threshold.

Further, the consensus process of step 10 is as follows:

Step 10-1, the RSU (denoted as r _sz , sz = 1, 2, 3...l) undertaking the consensus work in the vehicle ad hoc network will store a list of its own set of trusted nodes locally

In the consensus phase, r _sz only believes its collection

The voting results of mid-nodes;

Step 10-2, each r _sz will try its best to collect the vehicle reputation score update information broadcast in the consensus network (denoted as

). Before the start of each round of consensus, a total vehicle reputation score update information set needs to be initialized

To get this set, r _sz will

With its trusted node collection

The vehicle reputation score update information collected by the mid-node is merged to obtain

Step 10-3,

Node pair set

Each vehicle’s reputation score update information is voted, and the number of voting rounds is equal to the set

The total number of messages in. If a node does not vote in time at each voting stage, it will be removed

And cannot vote in the later voting stage;

Step 10-4, in the voting stage, if the information being voted for is less than p, the information will be re-inserted

Waiting for the next consensus, if the voting rate is greater than or equal to p, then this information is voted through. Where p is the threshold for the rate of yes votes.

The beneficial effects achieved by the present invention are:

1. Use ring signature technology to protect the privacy of the vehicle and prevent the vehicle from being tracked by malicious attackers.

2. The reputation evaluation mechanism is used to evaluate the information in the Internet of Vehicles, effectively preventing internal attackers from forging information to damage the security of Internet of Vehicles.

3. Use blockchain technology to protect the vehicle reputation score stored on the RSU and prevent intruders from tampering with it.

Description of the drawings

Figure 1 is a schematic diagram of the system model of the present invention.

Figure 2 is a schematic diagram of the blockchain storage data according to the present invention.

Figure 3 is a flowchart of specific steps of the present invention.

Detailed ways

The technical solution of the present invention will be further described in detail below in conjunction with the accompanying drawings of the specification.

Step 1. The trusted authority center TA chooses E _k (x) as a symmetric encryption protocol that uses a key k to encrypt x. The public key and private key of the symmetric encryption protocol are the same key, and at the same time select or generate the following public parameters or Object:

Step 1-1, select G as the additive group whose point is on the elliptic curve, q is the order of G, and g is the generator of G.

Step 1-2, choose H as the hash function, H: {0,1}*→{0,1} ⁿ , that is, map an arbitrary length of 0,1 data set to a 0,1 data set of length n.

Step 1-3, generate

Means from

(Set of integers of arbitrary length with order q) randomly select elements from the set and assign values to X ₁ ,..., X _n , Y _i =X _i *g, X _i ∈ (X ₁ ,..., X _n ).

Step 1-4, generate

To manage the private key vector,

To manage the public key vector.

Step 2: When the vehicle joins the vehicle ad hoc network for the first time, the reputation score is initialized; at the same time, the vehicle user uses his real identity ID to obtain his public-private key pair and pseudonym, that is, the public key address from the trusted authority center TA.

The step 2 specifically includes the following sub-steps:

Step 2-1, TA initializes the reputation score of the vehicle to R (0≤R≤1).

Step 2-2, TA generates the on-board user private key according to the real ID

(h _i is the content of the i-th bit of H(ID), i=1,...n), and the vehicle user public key

The public key address addrpk=H(sk _ID ); the private key of the vehicle-mounted user is stored in the TA and is not publicly disclosed; the public-private key pair of the vehicle-mounted user is used in the signature, and the public key address, namely the pseudonym, is used in the blockchain.

Step 3. When a vehicle witnesses a traffic incident on the road, he will share this traffic message msg with other vehicles in the on-board ad hoc network, and call this vehicle the initiating vehicle; others around are witnesses to help prove The vehicle that reports the authenticity of the msg is called the corroborating vehicle.

Step 4. After the initiating vehicle witnesses the traffic incident, in order to obtain feedback from other supporting vehicles on the message, and to ensure the reliability of the message, a request message RQP is generated.

In the step 4, specifically, to ensure the reliability of the message, perform the following operations to generate a request message RQP:

Step 4-1, generate a ring signature to protect the privacy of the initiating vehicle. Arbitrary integers r and t; r is the length of the ring signature, and t is the length of the signature threshold.

Step 4-2, arbitrarily select rt IDs from the ID list set, expressed as S'={ID ₁ ,..., ID _rt }.

Step 4-3, for each ID _i ∈S', calculate

h _j is the content of the jth bit of H(ID), and Y _j is

The content of the jth bit.

Step 4-4, for each ID _i ∈S', generate

Means from

A set of integers of arbitrary length with order q, any selected element in the set is assigned to γ _i , and γ _{i is} used as the index of ID _i .

Means from

α _i ＝a _i ·g+b _i ·PK _i

β _i ＝-b _i ^-1 H(α _i )

m _i = a _i · β _i.

Step 5. Through the ring signature, the initiating vehicle will be broadcast anonymously; after the supporting vehicle receives the information of the initiating vehicle, it will return the supporting message RPP and the cipher text information EM of whether the generated message is reliable, that is, whether the supporting vehicle is reliable or not The encrypted data of the message.

The step 5 specifically includes the following sub-steps:

Step 5-1, to verify that the vehicle obtains the information (msg, r, t, Ω) in the request message RQP.

Step 5-2, generate

And γ does not belong to the set {γ ₁ ,..., γ _rt }, as the ID index of the supporting vehicle.

Step 5-3, generate

Calculate α=c·g and β=(m-sk _ID H(α))c ^-1 .

Step 5-4: Generate a supporting message RPP=(s, m, (α, β), ID), and send the RPP to the initiating vehicle.

Step 6. After the initiating vehicle receives enough supporting information (signature threshold is t), assume S={ID _r-t+1 ,...,ID _r }, and package these messages to generate aggregated message AGP ; The initiating vehicle sends AGP=(<γ ₁ , m ₁ , α ₁ , β ₁ >,..., <γ _r , m _r , α _r , β _r >, msg, t, S∪S') through the secure channel To the adjacent roadside unit (RSU).

Step 7-1, obtain (<ID ₁ , γ ₁ , m ₁ , α ₁ , β ₁ >,..., <ID _r , γ _r , m _r , α _r , β _r >, msg, t) from AGP.

Step 7-2, for each ID _i , calculate

(h _j is the content of the jth bit of H(ID), Y _j is

The content of the jth bit).

Step 7-3, for each ID _i , calculate m _i ·g=H(α _i )·PK+α _i β _i , if any set of <m _i , α _i , β _i > is not satisfied, then the ring signature The verification failed.

Step 7-4, calculate k=H(msg) and EM=E _k (z). If EM=E _k (1), then z=1; if EM=E _k (-1), then z=-1.

Step 8. The RSU queries the reputation scores of the initiating vehicles and supporting vehicles in the blockchain maintained by the RSU. Based on the reputation scores, the RSU will calculate the reliability of the message msg.

The reliability calculation process in step 8 is as follows:

Step 8-1, calculate the total reputation score value.

among them

Indicates the average credit score value of the supporting vehicles with a response of "-1", z _j and N respectively represent the credit value and number of supporting vehicles with a response of "-1".

Step 8-2, determine the weight.

Where w _i and w _j represent the weight of the supporting vehicle.

Step 8-3, weighting calculation.

among them

Respectively represent the weighted average of the credibility scores of supporting vehicles with the answers "1" and "-1".

Step 8-4, judge the reliability of the message msg.

Calculation

among them

Step 9. When the message msg calculation result is reliable, the RSU first broadcasts the message to other vehicles (called vehicles) within its communication range and increases the reputation score R _new for the initiating vehicle and the supporting vehicle with the reply information "1" =(1-s)R+R, R _new is the new vehicle reputation score after the update, and R is the vehicle reputation score before the update. When the message msg calculation result is unreliable, the RSU penalizes the initiating vehicle and the supporting vehicle whose reply information is "-1" to reduce the reputation score R _new =(1-t)R+R. Where 0≤s≤1, -1≤t≤0. RSU packs the updated information of the vehicle reputation score into blocks and broadcasts it to the consensus network.

The consensus process of step 10 is as follows:

In the consensus phase, r _sz only believes its collection

The voting result of the middle node.

To get this set, r _sz will

With its trusted node collection

Step 10-3,

Node pair set

And cannot vote in the later voting stage.

The above are only preferred embodiments of the present invention, and the scope of protection of the present invention is not limited to the above embodiments. However, all equivalent modifications or changes made by those of ordinary skill in the art based on the disclosure of the present invention should be included Within the scope of protection described in the claims.

Claims

A blockchain-based privacy protection trust model for the Internet of Vehicles is characterized by the following steps:

Step 1. The trusted authority center TA selects E k (x) as a symmetric encryption protocol that uses a key k to encrypt x, and the public key and private key of the symmetric encryption protocol are the same key, and at the same time selects or generates public parameters or objects;

Step 2: When the vehicle joins the vehicle ad hoc network for the first time, the reputation score is initialized; at the same time, the vehicle user uses his real identity ID to obtain his public-private key pair and pseudonym, that is, the public key address, from the trusted authority center TA;

Step 3. When a vehicle witnesses a traffic incident on the road, he will share this traffic message msg with other vehicles in the on-board ad hoc network, and call this vehicle the initiating vehicle; others around are witnesses to help prove The vehicle with the authenticity of the msg message is called the corroborating vehicle;

Step 4. After the initiating vehicle witnesses the traffic incident, in order to obtain feedback from other supporting vehicles on the message, and to ensure the reliability of the message, a request message RQP is generated;

Step 5. Through the ring signature, the initiating vehicle will be broadcast anonymously; after the supporting vehicle receives the information of the initiating vehicle, it will return the supporting message RPP and the cipher text information EM of whether the generated message is reliable, that is, whether the supporting vehicle is reliable or not Encrypted data of the message;

Step 6. After the initiating vehicle receives enough supporting information (signature threshold is t), assume S={ID r-t+1 ,...,ID r }, and package these messages to generate aggregated message AGP ; The initiating vehicle sends AGP=(<γ 1 , m 1 , α 1 , β 1 >,..., <γ r , m r , α r , β r >, msg, t, S∪S') through the secure channel To the adjacent roadside unit (RSU);

Step 7. After the RSU receives the AGP of the initiating vehicle, it does the following:

Step 7-1, obtain (<ID 1 , γ 1 , m 1 , α 1 , β 1 >,..., <ID r , γ r , m r , α r , β r >, msg, t) from AGP;

Step 7-2, for each ID i , calculate
(h j is the content of the jth bit of H(ID), Y j is
The content of bit j);

Step 7-3, for each ID i , calculate m i ·g=H(α i )·PK+α i β i , if any set of <m i , α i , β i > is not satisfied, then the ring signature Verification failed;

Step 7-4, calculate k=H(msg) and EM=E k (z). If EM=E k (1), then z=1; if EM=E k (-1), then z=-1;

Step 8. RSU queries the reputation scores of the initiating vehicles and supporting vehicles in the blockchain maintained by the RSU. Based on the reputation scores, the RSU will calculate the reliability of the message msg;

Step 9. When the message msg calculation result is reliable, the RSU first broadcasts the message to other vehicles (called vehicles) within its communication range and increases the reputation score R new for the initiating vehicle and the supporting vehicle with the reply information "1" =(1-s)R+R, R new is the new vehicle reputation score after the update, and R is the vehicle reputation score before the update. When the message msg calculation result is unreliable, the RSU penalizes the initiating vehicle and the supporting vehicle whose reply information is "-1" to reduce the reputation score R new =(1-t)R+R. Where 0≤s≤1, -1≤t≤0. RSU packs the updated information of the vehicle reputation score into blocks and broadcasts it to the consensus network;

Step 10: The RSU responsible for the consensus work in the vehicle ad hoc network carries out a consensus on the update of the vehicle reputation score. After the consensus phase is over, all RSUs record the new vehicle reputation score in the blockchain ledger maintained by themselves.
The privacy protection trust model for the Internet of Vehicles based on blockchain according to claim 1, wherein the public parameters or objects selected or generated in step 1 are as follows:

Step 1-1, select G as the additive group whose point is on the elliptic curve, q is the order of G, and g is the generator of G;

Step 1-2, select H as the hash function, H: {0,1}*→{0,1} n , that is, map an arbitrary length of 0,1 data set to a 0,1 data set of length n;

Step 1-3, generate
Means from
(Set of integers of arbitrary length with order q) Assign values to X 1 ,..., X n , Y i =X i *g, X i ∈(X 1 ,..., X n ) by randomly selecting elements in the set;

Step 1-4, generate
To manage the private key vector,

To manage the public key vector.
A blockchain-based privacy protection trust model for the Internet of Vehicles according to claim 1, wherein the step 2 specifically includes the following sub-steps:

Step 2-1, TA initializes the reputation score of the vehicle as R (0≤R≤1);

Step 2-2, TA generates the on-board user private key according to the real ID
(h i is the content of the i-th bit of H(ID), i=1,...n), and the vehicle user public key
The public key address addrpk=H(sk ID ); the private key of the vehicle user is stored in the TA and is not publicly disclosed; the public and private key pair of the vehicle user is used in the signature, and the public key address, namely the pseudonym, is used in the blockchain;

Step 2-3, all roadside units (RSU) in the vehicle ad hoc network store the pseudonym addrpk and reputation score R of the vehicle into the blockchain maintained by themselves.
The privacy protection trust model of the Internet of Vehicles based on blockchain according to claim 1, characterized in that: in step 4, specifically, to ensure the reliability of the message, the following operations are performed to generate a request message RQP:

Step 4-1, generate a ring signature to protect the privacy of the initiating vehicle. Arbitrary integers r and t; r is the length of the ring signature, and t is the length of the signature threshold;

Step 4-2, arbitrarily select rt IDs from the ID list set, expressed as S'={ID 1 ,..., ID rt };

Step 4-3, for each ID i ∈S', calculate
h j is the content of the jth bit of H(ID), and Y j is
The content of the j-th bit;

Step 4-4, for each ID i ∈S', generate
Means from
A set of integers of arbitrary length with order q, randomly selected elements in the set are assigned to γ i , and γ i is used as the index of ID i ;

Step 4-5, calculate the EC-Elgamal signature for each ID i ∈S'; generate a i ,
Means from
A set of integers of arbitrary length with order q, randomly select elements in the set and assign values to a i and b i , calculate

α i ＝a i ·g+b i ·PK i

β i ＝-b i -1 H(α i )

m i = a i · β i.

Steps 4-6, define Ω=({ID 1 ,..., ID rt }, {γ 1 ,...,γ rt }, {m 1 ,..., m rt }), RQP=(msg, r, t, Ω ).
The privacy protection trust model of the Internet of Vehicles based on the blockchain according to claim 1, wherein the step 5 specifically includes the following sub-steps:

Step 5-1, supporting the vehicle to obtain the information (msg, r, t, Ω) in the request message RQP;

Step 5-2, generate
And γ does not belong to the set {γ 1 ,..., γ rt }, as the ID index of the supporting vehicle;

Step 5-3, generate
Calculate α=c·g and β=(m-sk ID H(α))c -1 ;

Step 5-4, generate a supporting message RPP=(s,m,(α,β),ID), and send the RPP to the initiating vehicle;

Step 5-5: Calculate k=H(msg), and generate variable z to represent whether the vehicle considers the message msg to be reliable. If z=1, it is considered reliable, otherwise -1 is unreliable. EM=E k (z), send EM to RSU.
A blockchain-based privacy protection trust model for the Internet of Vehicles according to claim 1, wherein the reliability calculation process in step 8 is as follows:

Step 8-1, calculate the total reputation score;

among them
Indicates the average credit score value of the supporting vehicles with a response of "1", z i and M respectively represent the credit value and number of supporting vehicles with a response of "1".
Indicates the average credit score value of the supporting vehicles with a response of "-1", z j and N respectively represent the credit value and number of supporting vehicles with a response of "-1";

Step 8-2, determine the weight;

Where w i and w j represent the weight of the supporting vehicle;

Step 8-3, weighting calculation;

among them
Respectively indicate the weighted average of the credibility scores of supporting vehicles with the answers "1" and "-1";

Step 8-4, judge the reliability of the message msg;

Calculation
among them

If the calculation result meets the conditions in the above formula, the message msg is considered reliable, and minRe is the threshold.
The privacy protection trust model of car networking based on blockchain according to claim 1, characterized in that: the consensus process of step 10 is as follows:

Step 10-1, the RSU (denoted as r sz , sz = 1, 2, 3...l) undertaking the consensus work in the vehicle ad hoc network will store a list of its own set of trusted nodes locally
In the consensus phase, r sz only believes its collection
The voting results of mid-nodes;

Step 10-2, each r sz will try its best to collect the vehicle reputation score update information broadcast in the consensus network (denoted as
). Before the start of each round of consensus, a total vehicle reputation score update information set needs to be initialized
To get this set, r sz will
With its trusted node collection
The vehicle reputation score update information collected by the mid-node is merged to obtain

Step 10-3,
Node pair set
Each vehicle’s reputation score update information is voted, and the number of voting rounds is equal to the set
The total number of messages in. If a node does not vote in time at each voting stage, it will be removed
And cannot vote in the later voting stage;

Step 10-4, in the voting stage, if the information being voted for is less than p, the information will be re-inserted
Waiting for the next consensus, if the voting rate is greater than or equal to p, then this information is voted through. Where p is the threshold for the rate of yes votes.