CN113949989A - Location-based service query method and system for privacy protection in road network environment - Google Patents

Abstract

The invention discloses a location-based service query method and a location-based service query system for privacy protection in a road network environment, wherein the method comprises the following steps: the registration of a user and a position-based service provider is realized through a trusted center, wherein the trusted center generates system parameters according to the Chinese remainder theorem, namely the Chinese remainder theorem; providing, by the location-based service provider, a location-based service query, including road conditions of the potential route and the optimal route, to the user according to the oblivious transmission method; the user and the position-based service provider communicate through a roadside unit, wherein the wireless communication between the roadside unit and the user is realized by the IEEE802.11p standard, and the communication between the roadside unit and the position-based service provider is realized by a wired link or a low-latency high-bandwidth wireless link. The invention can protect the query content and the position privacy of the user, and has lower calculation cost and communication cost, thereby being more suitable for the position-based service query in the road network environment.

Description

Location-based service query method and system for privacy protection in road network environment

Technical Field

The invention relates to the technical field of location-based service, in particular to a location-based service query method and system for privacy protection in a road network environment.

Background

In a road network environment, a user usually needs to use a wireless communication technology to send Location information and a query report to a Location-Based Service Provider (LSP) in order to obtain Location-Based Service (LBS). A typical LBS includes: point of interest search, route navigation, location-based recommendation services, and the like. However, the query content and location information of the user in LBS are at risk of leakage, for example, the LSP reveals the location privacy and query content of the user to a malicious adversary due to a relationship of interest. Leakage of location privacy can seriously threaten user property and personal safety, for example, a user can often inquire road conditions near a hospital and can conclude that the user has a possible health problem; the user may then infer his or her likely home address by using location based query services frequently during off-hours.

Location privacy protection LBS has received wide attention, and existing privacy protection technologies in location-based services mainly include k-anonymization technology, false identity technology, location perturbation technology, homomorphic encryption technology and oblivious transmission technology, among them:

(1) the basic idea of k-anonymization technology is that a user sends the real position and the query content of the user to a credible anonymization server, and the anonymization server generates an anonymization query report containing the positions of other k-1 users for the anonymization server and sends the anonymization query report to the LSP. At the moment, the accuracy rate of the LSP associated user and the query report does not exceed 1/k. However, if the query generated by the anonymizing server is too large, the query overhead for the LSP may be increased.

(2) The main idea of the false identity technology is that a user uses a false user identity to replace a real user identity when sending a request report, so as to achieve the purpose of confusing the corresponding relationship between the user identity and the location. However, in the case of low regional traffic, an attacker can eavesdrop on the query report and successfully track the target user.

(3) The main idea of location random perturbation is that the user replaces his real location with a false or perturbed location and adds to the service request. However, a drawback of this technique is that the large number of false locations increases the computational overhead of the location-based server and the latency of query service requests.

(4) The main idea of homomorphic encryption technology is to protect the location privacy of the user through operations on the ciphertext. However, this technique requires high computational overhead and does not support scenes with a large user density.

(5) The oblivious transmission technology protects the position privacy of a user by hiding the inquiry position, but the calculation overhead and the communication cost of the technology are in direct proportion to the data dimension.

In summary, the current privacy protection based location service framework is mainly designed by using k-anonymity, false identity, location disturbance, homomorphic encryption and careless transmission technologies, and the user location privacy in the k-anonymity based location service framework is easy to eavesdrop; a large number of false locations in a location random perturbation based framework can increase the computation overhead and the latency of query service requests based on the location server; a homomorphic encryption-based framework causes high calculation overhead and does not support scenes with high user density; the problem that computational and communication overhead in the framework of oblivious transmission is proportional to the data dimension.

Disclosure of Invention

In order to solve the problems, the invention provides a location-based service query method and a location-based service query system for privacy protection in a road network environment based on an accidental transmission technology and the Chinese remainder theorem, which can protect query contents and location privacy of users and have lower calculation cost and communication cost, so that the location-based service query method and the location-based service query system are more suitable for location-based service query in the road network environment.

The technical scheme adopted by the invention is as follows:

a location-based service query method for privacy protection in a road network environment comprises the following steps:

the registration of a user U and a location-based service provider LSP is realized through a trusted center TA, wherein the trusted center TA generates system parameters according to a Chinese remainder theorem, namely a Chinese remainder theorem;

providing a location-based service query for a user U according to an oblivious transmission method based on a location service provider LSP, wherein the content of the location-based service query comprises road conditions of potential routes and an optimal route;

the user U and the LSP based on the position service provider are communicated through a roadside unit RSU, wherein the wireless communication between the roadside unit RSU and the user U is realized by the IEEE802.11p standard, and the communication between the roadside unit RSU and the LSP based on the position service provider is realized by a wired link or a low-delay high-bandwidth wireless link.

Further, the trusted center TA generates the system parameters by:

s101, selecting a curve satisfying an ellipse E: y²＝x³A finite field F formed by the points (x, y) of + ax + bmod_pWherein a, b ∈ F_p，4a³+27b²Not equal to 0, p is a big prime number; all points (x, y) on E and the infinite point O form an addition group

The generator is P, and the order is prime number q;

s102, randomly selecting a system master key

Wherein

Representing a set of positive integers and computing a system public key P_pub＝sP；

S103, selecting a Hash function

S104, selecting prime number q₁,q₂,…,q_nAnd calculating:

the road area is divided into n road segments, each of which is represented by a two-dimensional identifier { u } approximating the location coordinates_k,v_kDenotes, where k is 1,2, …, n, for the designation { u }_k,v_kRoad segment assignment of α_kWhere k ∈ {1, …, n };

s105, publishing system parameters

And secretly holds the system master key s.

Further, the registration of the user U by the trust center TA includes: the user U generates the private key sk by the following steps_uAnd public key PK_u：

S201, setting a secret value: random selection of secret value by user U

Calculating the public value X_u＝x_uP, and transmits a secret value X_uAnd identity information ID_uSending the information to a trusted center TA;

s202, extracting a part of private keys: receiving secret value X_uAnd identity information ID_uThereafter, the trusted center TA randomly selects

Computing a partial public key R_u＝r_uP and blinded partial private key g_u＝r_u+H₀(s·X_u)+s·H₁(ID_u,R_u,X_u,P_pub) And return R_uAnd g_uGiving a user U;

s203, setting a private key: the user U first calculates a partial private key d_u＝g_u-H₀(x_u·P_pub) Then verify d_uP＝R_u+H₁(ID_u,R_u,X_u,P_pub)P_pubWhether the result is true or not; if yes, the user U sets the private key sk_u＝{x_u,d_u}; otherwise, terminating;

s204, setting a public key: user U sets up public key PK_u＝{X_u,R_u}。

Further, the implementation of location based service provider LSP registration by trusted center TA includes: generating a private key sk based on a location service provider LSP by_lspAnd public key PK_lsp；

S301, setting a secret value: randomly selecting a secret value based on a location service provider LSP

Calculating the public value X_lsp＝x_lspP, and sends the public value X_lspAnd identity information ID_lspSending the information to a trusted center TA;

s302, extracting a part of private keys: the trusted center TA receives the public value X_lspAnd identity information ID_lspThen, randomly selecting

Computing a partial public key R_lsp＝r_lspP and blinded partial private key g_lsp＝r_lsp+H₀(s·X_lsp)+s·H₁(ID_lsp,R_lsp,X_lsp,P_pub) And return R_lspAnd g_lspProviding a location based service provider LSP;

s303, setting a private key: first computing a partial private key d based on a location service provider LSP_u＝g_lsp-H₀(x_lsp·P_pub) Then verify d_lspP＝R_lsp+H₁(ID_lsp,R_lsp,X_lsp,P_pub)P_pubWhether the result is true or not; if yes, setting a private key sk based on the LSP of the location service provider_lsp＝{x_lsp,d_lsp}; otherwise, terminating;

s304. set upPublic key: setting public key PK based on location service provider LSP_lsp＝{X_lsp,R_lsp}。

Further, assume that the segment identification { u } is to be queried_k,v_kFor road conditions, user U generates a query report by:

s401, user U randomly selects

And calculating:

A_u＝a_uP，B_u＝b_uP，M_u＝u_u+x_uA_u，N_u＝v_u+x_uB_u，L_u＝l_uP，

σ_u＝d_u+x_uH₂(ID_u,X_u,R_u)+l_uH₃(ID_u,A_u,B_u,M_u,N_u,L_u)；

s402, user U sends query report { A_u,B_u,M_u,N_u,L_u,σ_uGiving location based service provider LSPs.

Further, a query report is received based on the location service provider LSP { A_u,B_u,M_u,N_u,L_u,σ_uAfter, generating a reply report by the following steps:

s501, verifying whether the following equation is true based on the location service provider LSP:

σ_uP＝R_u+H₁(ID_u,R_u,X_u,P_pub)P_pub+H₂(ID_u,X_u,R_u)X_u+H₃(ID_u,A_u,B_u,M_u,N_u,L_u)L_u

if yes, accept the inquiry report { A_u,B_u,M_u,N_u,L_u,σ_u}; otherwise, rejecting;

s502. random selection

And calculating:

L_lsp＝l_lspP，σ_lsp＝d_lsp+x_lspH₂(ID_lsp,X_lsp,R_lsp)+l_lspH₃(ID_lsp,Θ_lsp,Φ_lsp,Δ_lsp,L_lsp)；

s503, sending a reply report { theta }_lsp,Φ_lsp,Δ_lsp,L_lsp,σ_lspGive user U.

Further, user U receives reply report { Θ }_lsp,Φ_lsp,Δ_lsp,L_lsp,σ_lspAfter that, the identification { u } is obtained by the following steps_k,v_kRoad condition data m of a section of road_k：

S601. the user U verifies whether the following equation holds

σ_lspP＝R_lsp+H₁(ID_lsp,R_lsp,X_lsp,P_pub)P_pub+H₂(ID_lsp,X_lsp,R_lsp)X_lsp+H₃(ID_lsp,Θ_lsp,Φ_lsp,Δ_lsp,L_lsp)L_lsp

If yes, the user U accepts the reply report { theta }_lsp,Φ_lsp,Δ_lsp,L_lsp,σ_lsp}; otherwise, rejecting;

s602. the user U reads the road condition data m_k＝Δ_lspmodα_k-H₄(Φ_lsp-x_uΘ_lsp)。

A location-based service query system for privacy protection in a road network environment, comprising:

a location based service provider LSP for providing a location based service query to a user U according to an oblivious transmission method, the content of the location based service query including road conditions of potential routes and an optimal route;

the trusted center TA is used for generating system parameters according to the Chinese remainder theorem, namely the Chinese remainder theorem, realizing the registration of the user U and the LSP based on the position service provider and updating the system information regularly;

and the roadside unit RSU is used for completing the communication between the user U and the LSP based on the position service provider, wherein the wireless communication between the roadside unit RSU and the user U is realized by the IEEE802.11p standard, and the communication between the roadside unit RSU and the LSP based on the position service provider is realized by a wired link or a low-delay high-bandwidth wireless link.

The invention has the beneficial effects that:

existing privacy-preserving location-based service frameworks are designed primarily with k-anonymity, false identity, location perturbation, homomorphic encryption, and oblivious transmission techniques. However, the existing solutions either have poor performance (high computational overhead and communication bandwidth) and cannot meet the security requirements (query content and location privacy protection) in the road network environment. The location-based service query method and system for privacy protection in the road network environment can protect query contents and location privacy of users, and have lower calculation overhead and communication cost, so that the location-based service query method and system are more suitable for location-based service query in the road network environment.

Drawings

Fig. 1 is a schematic diagram of a location-based service query system for privacy protection in a road network environment according to an embodiment of the present invention.

Detailed Description

In order to more clearly understand the technical features, objects, and effects of the present invention, specific embodiments of the present invention will now be described. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without making any creative effort, shall fall within the protection scope of the present invention.

The present embodiment provides a Location-Based Service query system for privacy protection in a Road network environment, as shown in fig. 1, the Location-Based Service query system includes a Trusted Authority (TA), a Location-Based Service Provider (LSP) and a Road Side Unit (RSU). The trusted center TA generates system parameters according to the chinese remainder theorem, i.e., the chinese remainder theorem, thereby realizing registration of the user U and the LSP based on the location service provider, and periodically updating system information. The location based service provider LSP provides a location based service query to a User (User, U) according to an oblivious transmission method, the content of which includes road conditions of the potential route and the best route. The roadside unit RSU completes the communication between the user U and the LSP based on the position service provider, wherein the wireless communication between the roadside unit RSU and the user U is realized by the IEEE802.11p standard, and the communication between the roadside unit RSU and the LSP based on the position service provider is realized by a wired link or a low-delay high-bandwidth wireless link.

In the present embodiment, it is assumed that the location-based service provider LSP is honest but curious, i.e. it is both able to correctly perform the operations defined in the protocol, and to attempt to infringe the privacy of the vehicle by analyzing the query reports; also, it is assumed that there is an attacker who can eavesdrop on the data transmission and launch the attack. The road area is divided into n road segments, each of which is represented by a two-dimensional identifier { u } approximating the location coordinates_k,v_kDenotes, where k is 1,2, …, n.

Correspondingly, the embodiment also provides a location-based service query method for privacy protection in a road network environment, which includes a system establishment algorithm, a user registration algorithm, a location-based server registration algorithm, a location-based service query algorithm, a location-based service reply algorithm, and a location-based service reading algorithm, wherein:

(1) the system establishment algorithm comprises the following steps: the trusted center TA generates system parameters by:

s101, selecting a curve satisfying an ellipse E: y²＝x³A finite field F formed by the points (x, y) of + ax + bmod_pWherein a, b ∈ F_p，4a³+27b²Not equal to 0, p is a big prime number; all points (x, y) on E and the infinite point O form an addition group

The generator is P, and the order is prime number q;

s102, randomly selecting a system master key

Wherein

Representing a set of positive integers and computing a system public key P_pub＝sP；

S103, selecting a Hash function

S104, selecting prime number q₁,q₂,…,q_nAnd calculating:

the road area is divided into n road segments, each of which is represented by a two-dimensional identifier { u } approximating the location coordinates_k,v_kDenotes, where k is 1,2, …, n, for the designation { u }_k,v_kRoad segment assignment of α_kWhere k ∈ {1, …, n };

s105, publishing system parameters

And secretly holds the system master key s.

(2) The user registration algorithm: the user U passes through the following stepsStep generation of the private key sk_uAnd public key PK_u：

S201, setting a secret value: random selection of secret value by user U

Calculating the public value X_u＝x_uP, and transmits a secret value X_uAnd identity information ID_uSending the information to a trusted center TA;

s202, extracting a part of private keys: receiving secret value X_uAnd identity information ID_uThereafter, the trusted center TA randomly selects

Computing a partial public key R_u＝r_uP and blinded partial private key g_u＝r_u+H₀(s·X_u)+s·H₁(ID_u,R_u,X_u,P_pub) And return R_uAnd g_uGiving a user U;

s203, setting a private key: the user U first calculates a partial private key d_u＝g_u-H₀(x_u·P_pub) Then verify d_uP＝R_u+H₁(ID_u,R_u,X_u,P_pub)P_pubWhether the result is true or not; if yes, the user U sets the private key sk_u＝{x_u,d_u}; otherwise, terminating;

s204, setting a public key: user U sets up public key PK_u＝{X_u,R_u}。

(3) Location based service provider registration algorithm: generating a private key sk based on a location service provider LSP by_lspAnd public key PK_lsp；

S301, setting a secret value: randomly selecting a secret value based on a location service provider LSP

Calculating the public value X_lsp＝x_lspP, and sends the public value X_lspAnd identity information ID_lspSending the information to a trusted center TA;

s302, extracting a part of private keys: the trusted center TA receives the public value X_lspAnd identity information ID_lspThen, randomly selecting

Computing a partial public key R_lsp＝r_lspP and blinded partial private key g_lsp＝r_lsp+H₀(s·X_lsp)+s·H₁(ID_lsp,R_lsp,X_lsp,P_pub) And return R_lspAnd g_lspProviding a location based service provider LSP;

s303, setting a private key: first computing a partial private key d based on a location service provider LSP_u＝g_lsp-H₀(x_lsp·P_pub) Then verify d_lspP＝R_lsp+H₁(ID_lsp,R_lsp,X_lsp,P_pub)P_pubWhether the result is true or not; if yes, setting a private key sk based on the LSP of the location service provider_lsp＝{x_lsp,d_lsp}; otherwise, terminating;

s304, setting a public key: setting public key PK based on location service provider LSP_lsp＝{X_lsp,R_lsp}。

(4) Location based service query algorithm: suppose that the road segment identification u is to be queried_k,v_kFor road conditions, user U generates a query report by:

s401, user U randomly selects

And calculating:

A_u＝a_uP，B_u＝b_uP，M_u＝u_u+x_uA_u，N_u＝v_u+x_uB_u，L_u＝l_uP，

σ_u＝d_u+x_uH₂(ID_u,X_u,R_u)+l_uH₃(ID_u,A_u,B_u,M_u,N_u,L_u)；

s402, user U sends query report { A_u,B_u,M_u,N_u,L_u,σ_uGiving location based service provider LSPs.

(5) Location based service reply algorithm: receipt of query report based on location service provider LSP { A_u,B_u,M_u,N_u,L_u,σ_uAfter, generating a reply report by the following steps:

s501, verifying whether the following equation is true based on the location service provider LSP:

σ_uP＝R_u+H₁(ID_u,R_u,X_u,P_pub)P_pub+H₂(ID_u,X_u,R_u)X_u+H₃(ID_u,A_u,B_u,M_u,N_u,L_u)L_u

if yes, accept the inquiry report { A_u,B_u,M_u,N_u,L_u,σ_u}; otherwise, rejecting;

s502. random selection

And calculating:

L_lsp＝l_lspP，σ_lsp＝d_lsp+x_lspH₂(ID_lsp,X_lsp,R_lsp)+l_lspH₃(ID_lsp,Θ_lsp,Φ_lsp,Δ_lsp,L_lsp)；

s503, sending a reply report { theta }_lsp,Φ_lsp,Δ_lsp,L_lsp,σ_lspGive user U.

(6) Location based service reading algorithm: user U receives reply report { theta }_lsp,Φ_lsp,Δ_lsp,L_lsp,σ_lspAfter that, the identification { u } is obtained by the following steps_k,v_kRoad condition data m of a section of road_k：

S601. the user U verifies whether the following equation holds

σ_lspP＝R_lsp+H₁(ID_lsp,R_lsp,X_lsp,P_pub)P_pub+H₂(ID_lsp,X_lsp,R_lsp)X_lsp+H₃(ID_lsp,Θ_lsp,Φ_lsp,Δ_lsp,L_lsp)L_lsp

If yes, the user U accepts the reply report { theta }_lsp,Φ_lsp,Δ_lsp,L_lsp,σ_lsp}; otherwise, rejecting;

s602. the user U reads the road condition data m_k＝Δ_lspmodα_k-H₄(Φ_lsp-x_uΘ_lsp)。

It should be noted that, for the sake of simplicity, the present embodiment is described as a series of acts, but those skilled in the art should understand that the present application is not limited by the described order of acts, because some steps may be performed in other orders or simultaneously according to the present application. Further, those skilled in the art should also appreciate that the embodiments described in the specification are preferred embodiments and that the acts and modules referred to are not necessarily required in this application.

Claims (8)

1. A location-based service query method for privacy protection in a road network environment is characterized by comprising the following steps:

the registration of a user U and a location-based service provider LSP is realized through a trusted center TA, wherein the trusted center TA generates system parameters according to a Chinese remainder theorem, namely a Chinese remainder theorem;

providing a location-based service query for a user U according to an oblivious transmission method based on a location service provider LSP, wherein the content of the location-based service query comprises road conditions of potential routes and an optimal route;

the user U and the LSP based on the position service provider are communicated through a roadside unit RSU, wherein the wireless communication between the roadside unit RSU and the user U is realized by the IEEE802.11p standard, and the communication between the roadside unit RSU and the LSP based on the position service provider is realized by a wired link or a low-delay high-bandwidth wireless link.

2. The location-based service query method for privacy protection in road network environment according to claim 1, wherein the trusted center TA generates system parameters by:

s101, selecting a curve satisfying an ellipse E: y²＝x³A finite field F formed by the points (x, y) of + ax + b mod p_pWherein a, b ∈ F_p，4a³+27b²Not equal to 0, p is a big prime number; all points (x, y) on E and the infinite point O form an addition group

The generator is P, and the order is prime number q;

s102, randomly selecting a system master key

Wherein

Representing a set of positive integers and computing a system public key P_pub＝sP；

S103, selecting a Hash function

S104, selecting prime number q₁,q₂,…,q_nAnd calculating:

the road area is divided into n road segments, each of which is represented by a two-dimensional identifier { u } approximating the location coordinates_k,v_kDenotes, where k is 1,2, …, n, for the designation { u }_k,v_kRoad segment assignment of α_kWhere k ∈ {1, …, n };

s105, publishing system parameters

And secretly holds the system master key s.

3. The location-based service query method for privacy protection in road network environment according to claim 2, wherein the registration of the user U by the trust center TA comprises: the user U generates the private key sk by the following steps_uAnd public key PK_u：

S201, setting a secret value: random selection of secret value by user U

Calculating the public value X_u＝x_uP, and transmits a secret value X_uAnd identity information ID_uSending the information to a trusted center TA;

s202, extracting a part of private keys: receiving secret value X_uAnd identity information ID_uThereafter, the trusted center TA randomly selects

Computing a partial public key R_u＝r_uP and blinded partial private key g_u＝r_u+H₀(s·X_u)+s·H₁(ID_u,R_u,X_u,P_pub) And return R_uAnd g_uGiving a user U;

s203, setting a private key: the user U first calculates a partial private key d_u＝g_u-H₀(x_u·P_pub) Then verify d_uP＝R_u+H₁(ID_u,R_u,X_u,P_pub)P_pubWhether the result is true or not; if yes, the user U sets the private key sk_u＝{x_u,d_u}; otherwise, terminating;

s204, setting a public key: user U sets up public key PK_u＝{X_u,R_u}。

4. The method of claim 3, wherein the registration based on the location service provider LSP by the TA comprises: generating a private key sk based on a location service provider LSP by_lspAnd public key PK_lsp；

S301, setting a secret value: randomly selecting a secret value based on a location service provider LSP

Calculating the public value X_lsp＝x_lspP, and sends the public value X_lspAnd identity information ID_lspSending the information to a trusted center TA;

s302, extracting a part of private keys: the trusted center TA receives the public value X_lspAnd identity information ID_lspThen, randomly selecting

Computing a partial public key R_lsp＝r_lspP and blinded partial private key g_lsp＝r_lsp+H₀(s·X_lsp)+s·H₁(ID_lsp,R_lsp,X_lsp,P_pub) And return R_lspAnd g_lspProviding a location based service provider LSP;

s303, setting a private key: first computing a partial private key d based on a location service provider LSP_u＝g_lsp-H₀(x_lsp·P_pub) Then verify d_lspP＝R_lsp+H₁(ID_lsp,R_lsp,X_lsp,P_pub)P_pubWhether the result is true or not; if yes, setting a private key sk based on the LSP of the location service provider_lsp＝{x_lsp,d_lsp}; otherwise, terminating;

s304, setting a public key: setting public key PK based on location service provider LSP_lsp＝{X_lsp,R_lsp}。

5. The method of claim 4, wherein the road segment identification { u } is assumed to be queried_k,v_kFor road conditions, user U generates a query report by:

s401, user U randomly selects

And calculating:

A_u＝a_uP，B_u＝b_uP，M_u＝u_u+x_uA_u，N_u＝v_u+x_uB_u，L_u＝l_uP，

σ_u＝d_u+x_uH₂(ID_u,X_u,R_u)+l_uH₃(ID_u,A_u,B_u,M_u,N_u,L_u)；

s402, user U sends query report { A_u,B_u,M_u,N_u,L_u,σ_uGiving location based service provider LSPs.

6. The method of claim 5, wherein the location-based service provider LSP receives a query report { A }_u,B_u,M_u,N_u,L_u,σ_uAfter, generating a reply report by the following steps:

s501, verifying whether the following equation is true based on the location service provider LSP:

σ_uP＝R_u+H₁(ID_u,R_u,X_u,P_pub)P_pub+H₂(ID_u,X_u,R_u)X_u+H₃(ID_u,A_u,B_u,M_u,N_u,L_u)L_u

if yes, accept the inquiry report { A_u,B_u,M_u,N_u,L_u,σ_u}; otherwise, rejecting;

s502. random selection

And calculating:

s503, sending a reply report { theta }_lsp,Φ_lsp,Δ_lsp,L_lsp,σ_lspGive user U.

7. The method of claim 6, wherein the user U receives a reply report { Θ)_lsp,Φ_lsp,Δ_lsp,L_lsp,σ_lspAfter that, the identification { u } is obtained by the following steps_k,v_kRoad condition data m of a section of road_k：

S601. the user U verifies whether the following equation holds

σ_lspP＝R_lsp+H₁(ID_lsp,R_lsp,X_lsp,P_pub)P_pub+H₂(ID_lsp,X_lsp,R_lsp)X_lsp+H₃(ID_lsp,Θ_lsp,Φ_lsp,Δ_lsp,L_lsp)L_lsp

If yes, the user U accepts the reply report { theta }_lsp,Φ_lsp,Δ_lsp,L_lsp,σ_lsp}; otherwise, rejecting;

s602. the user U reads the road condition data m_k＝Δ_lspmodα_k-H₄(Φ_lsp-x_uΘ_lsp)。

8. An inquiry system based on the location-based service inquiry method for privacy protection in road network environment according to any one of claims 1 to 7, comprising:

a location based service provider LSP for providing a location based service query to a user U according to an oblivious transmission method, the content of the location based service query including road conditions of potential routes and an optimal route;

the trusted center TA is used for generating system parameters according to the Chinese remainder theorem, namely the Chinese remainder theorem, realizing the registration of the user U and the LSP based on the position service provider and updating the system information regularly;

and the roadside unit RSU is used for completing the communication between the user U and the LSP based on the position service provider, wherein the wireless communication between the roadside unit RSU and the user U is realized by the IEEE802.11p standard, and the communication between the roadside unit RSU and the LSP based on the position service provider is realized by a wired link or a low-delay high-bandwidth wireless link.

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