A pseudonym changing method based on neighbor density in a vehicle networking environment

Abstract

The application provides a vehicle networking position privacy protection method based on neighbor density, and the implementation steps are as follows: initializing a vehicle networking system; a central authorization agency generates a key and a pseudonym for each vehicle and performs pseudonym signing; the density of the neighbor area of each vehicle is judged; the vehicles exchange pseudonyms in a high-density area; and the pseudonym change result of the vehicles in a low-density area is obtained. According to the size of the neighbor area density where the vehicle is located when the pseudonym is about to expire each time, the area where the vehicle is located is divided into a high-density area and a low-density area, and different pseudonym update strategies are formulated for the two areas, which makes up for the neglect of the position privacy protection of the vehicles in non-hot area in the prior art, effectively improves the privacy of the vehicle position, appropriately reduces the cost of pseudonym application and management by using the pseudonym exchange mode in the high-density area, improves the pseudonym confusion degree and the un-linkability, and further improves the vehicle position privacy protection capability of the system.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of privacy computing, and relates to a pseudonym changing method in a vehicle networking environment, in particular to a pseudonym changing method based on neighbor density in a vehicle networking environment. BACKGROUND

[0002] Vehicle networking is evolved from traditional vehicle self-organizing network under the rapid development of Internet of Things and wireless communication technology, and is an integrated network capable of realizing intelligent traffic management, intelligent dynamic information service and vehicle intelligent control. Vehicle networking mainly completes communication between vehicles and between vehicles and infrastructure through short-range wireless communication technology, and in the communication process, vehicles periodically broadcast basic safety messages including important information such as vehicle identity, position and direction. However, the open form of broadcast in plaintext and the openness of wireless communication channel become potential threats to vehicle privacy and security.

[0003] In order to solve the problem of location privacy leakage in vehicle networking caused by broadcasting basic safety messages in plaintext, Corser et al. proposed a k-anonymity method in 2016, which requires at least K records for the same quasi-identifier, so that the observer cannot connect the records through the quasi-identifier, aiming to disturb the vehicle identity and protect the location privacy. Pseudonym changing is based on the idea of k-anonymity, and each vehicle with only one real identity is given K pseudonyms, and there is no association between the K pseudonyms. Vehicles constantly change pseudonyms to confuse the enemy, so that the enemy cannot associate all pseudonyms with the real identity of the vehicle and steal the privacy of the vehicle. Nowadays, pseudonym changing to protect location privacy in vehicle networking has become one of the most common solutions, but the eavesdropping enemy often links the vehicles before and after the pseudonym changing through two common attack methods of semantic linking and syntactic linking, and then steals the location information and other sensitive information in vehicle networking. Therefore, simple pseudonym changing is not enough to resist the linking attack of the enemy, and there are still problems such as limited application scenarios, resistance to only one kind of linking attack or security problems. In the process of protecting location privacy in vehicle networking based on pseudonym changing, how to realize the resistance to both kinds of linking attacks, and contain more changing scenarios, have higher security and privacy, is an urgent problem to be solved for realizing efficient and secure location privacy protection in vehicle networking.

[0004] For example, the patent application with the application publication number CN 114222304 A and the name "a pseudonym changing method based on silence and broadcast period in a vehicle networking environment" discloses a pseudonym changing method based on silence and broadcast period. The main steps of the method are: (1) collecting past vehicle trajectory data, screening all latitude and longitude coordinates that stay at the same position for more than a certain time to obtain stay points; (2) using the Mean Shift clustering method for stay points of different categories respectively, and obtaining clustering clusters according to the stay point density; (3) obtaining stay point areas based on the average value of stay point density and deploying the areas; (4) RSU applies for a pseudonym set from TA according to the number of stay point areas covered by the RSU, and each stay point area performs corresponding silence and broadcast period; (5) RSU allocates pseudonyms for vehicles entering the stay point area and specifies the life cycle of the pseudonyms, and all vehicles entering the stay point area cyclically use the pseudonyms in the pseudonym pool of the stay point area; (6) the vehicle is silent and changes the pseudonym allocated by the RSU until the silence period ends, and changes the next pseudonym in the own pseudonym pool to continue driving; (7) the vehicle resumes normal broadcasting and driving. The method has the following disadvantages: the screened stay point areas are usually areas that meet the condition of density exceeding the average density value, that is, the vehicle density is large enough to enter the stay point area and exchange pseudonyms, without considering the privacy problem of the vehicle being exposed in a sparse area for a long time, that is, in a low-density area. In addition, the pseudonym set in the stay point area is additionally applied for by the RSU from the trusted authority TA and is cyclically used, which not only generates a certain pseudonym application cost, but also easily causes the attacker to pay special attention to the stay point area and predict the position of the vehicle by using the pseudonym before and after, thereby weakening the privacy protection performance of the scheme. SUMMARY

[0005] The present application aims to solve the problem of weak privacy protection in the prior art.

[0006] To achieve the above-mentioned purpose, the technical solution adopted by the present application includes the following steps:

[0007] (1) Initialize the vehicle networking system:

[0008] Initialize the vehicle networking system including the central authority CA, I vehicles V={v1, v2, …, v i ,…v I} and M roadside units R={r1, r2, …, r m ,…r M}; initialize each vehicle v i Submit a registration request with a real identity ID i to the authority CA for req{ID iThe time interval between two kana changes is} The minimum stationary time of the pseudonym is τ, with R... i A circular region D with radius D i For vehicle v i The neighboring area, D i The dynamic set of vehicle kana to be exchanged is the pre-exchange kana set. The density threshold is ρ0, where I≥2, M≥2, v i Let r represent the i-th vehicle. m This represents the m-th roadside unit.

[0009] (2) The central authorized agency generates a key and pseudonym for each vehicle and performs pseudonym signing:

[0010] The centrally authorized agency CA passes through each vehicle v i Registration request req{ID i}for v i After verifying the identity of each vehicle, v i Generate public key PK i Private key SK i and the current time's kana Use your own private key SK CA For kana Sign the document to obtain a pseudonym certificate.

[0011] (3) Determine the density of the neighboring areas of each vehicle:

[0012] Each vehicle v i The pseudonym used during the journey satisfy At that time, based on the nearest roadside unit r d Get the current neighbor region Number of vehicles inside Calculate v i Neighbor density And judge Is it true? If so, then For high-density areas, and use pseudonyms Add to the pre-swapping kana set Then, proceed to step (4); otherwise, For low-density regions, step (5) is performed, where d∈M;

[0013] (4) Vehicles exchange pseudonyms in high-density areas:

[0014] (4a) When the set When the number of elements in a vector is greater than 1, the neighbor density is high for each vehicle v.n Select The pseudonym in vehicle v m Vehicle v n Using private key SK n For pseudonym certificates Perform the signature and obtain the signature result σ. n 'and include a timestamp t n ′, then use vehicle v m public key PK m Information encrypt and generate message ω n ′ and send to v m Where n≠m, and readyflag is a pre-exchange tag;

[0015] (4b) Vehicle v m Using private key SK m Decrypt ω n 'Get δ n Then use the public key to PK. n Verify signature σ n ′;If v m Agree with vehicle v n Cooperation, v m Using private key SK m For pseudonym certificates Perform the signature and obtain the signature result σ. m 'and include a timestamp t m Then use vehicle v n public key PK n Information encrypt and generate message ω m ′ and send to v n ;

[0016] (4c) Vehicle v n Using private key SK n Decrypt ω m 'Get δ m Then use the public key to PK. m Verify signature σ m ′;v n Using private key SK n For kana and certificates The signature result σ is obtained by performing the signature. n "and include a timestamp t" n "Then use vehicle v" m public key PK m Information Encrypt the message ω n "and sent to v m ;

[0017] (4d)v m Using private key SK m Decrypt ω n "Get δ" n Then use the public key to PK. n Verify signature σ n ", and the obtained v n kana Change to your own pseudonym; v m Using private key SK m For kana and certificates The signature result σ is obtained by performing the signature. m "and include a timestamp t" m "Then use vehicle v" n public key PK n Information Encrypt the message ω m "and sent to v n ;

[0018] (4e) Vehicle v n Using private key SK n Decrypt ω m "Get δ" m Then use the public key to PK. n Verify signature σ m ", and the obtained v m kana Change to your own pseudonym, and cooperate with vehicle v m At the same time, a period of silence will begin.

[0019] (5) Obtain the pseudonym change results for vehicles in low-density areas:

[0020] (5a) Each vehicle with a low neighbor density v h For the random result x generated using the SRNG random algorithm s+1 Perform modulo-2 operations and determine whether the number of choices g obtained from the modulo-2 operation satisfies g = 0. If so, change the kana. Change to the kana for the next moment Otherwise, proceed to step (5b);

[0021] (5b) Vehicle v h Random result x is generated using the SRNG random algorithm. s+2 Then, for the random result x s+2 Perform a modulo-3 operation and add one to obtain a random silence duration γ. Then, enter a silence period of duration γ before renaming the kana. Change to the kana for the next moment

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] 1. In this invention, each vehicle divides its neighboring region into high-density and low-density regions based on the density of its neighboring region when each pseudonym is about to expire. In the high-density region, the vehicle selects a willing partner to exchange pseudonyms with. In the low-density region, the vehicle uses a random algorithm to choose to directly change the pseudonym for the next moment or remain silent for a period of time before changing the pseudonym for the next moment. This pseudonym changing method based on neighbor density avoids the impact of existing technologies on vehicle location privacy protection due to the failure to consider the long-term exposure of vehicles to sparse traffic areas, and effectively improves the privacy of vehicle location.

[0024] 2. This invention uses pseudonym exchange among vehicles in high-density areas to change pseudonyms. Unlike existing technologies where RSUs apply for pseudonym pools for stop areas, pseudonym exchange reduces the cost of pseudonym application and management, while increasing the obfuscation and unlinkability of pseudonyms, further enhancing the location privacy protection capabilities of the Internet of Vehicles. Attached Figure Description

[0025] Figure 1 This is a flowchart illustrating the implementation of the present invention.

[0026] Figure 2 This is a flowchart illustrating the high-density pseudonym exchange process in this invention.

[0027] Figure 3 This is a flowchart illustrating the specific process of low-density random kana alteration in this invention. Detailed Implementation

[0028] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0029] Reference Figure 1 The present invention includes the following steps:

[0030] Step 1) Initialize the vehicle networking system:

[0031] Initialization includes the central authorization agency CA and I vehicles V = {v1, v2, ..., v...} i ,…v I} and M roadside units R = {r1, r2, ..., r m ,…r M The vehicle networking system; initializes each vehicle v i Submit your real identity ID to the authorized CA i The registration request is req{ID} i The time interval between two kana changes is} The minimum stationary time of the pseudonym is τ, with R...i A circular region D with radius D i For vehicle v i The neighboring area, D i The dynamic set of vehicle kana to be exchanged is the pre-exchange kana set. The density threshold is ρ0, where I≥2, M≥2, v i Let r represent the i-th vehicle. m This represents the m-th roadside unit. In this embodiment, I = 100, M = 5, τ = 30, R i =50, ρ0=0.15.

[0032] Step 2) The central authorized agency generates a key and pseudonym for each vehicle and performs pseudonym signing:

[0033] The centrally authorized agency CA passes through each vehicle v i Registration request req{ID i}for v i After verifying the identity of each vehicle, v i Generate public key PK i Private key SK i and the current time's kana Use your own private key SK CA For kana Sign the document to obtain a pseudonym certificate.

[0034] This embodiment completes vehicle registration based on the traditional Public Key Infrastructure (PKI) technology described in vehicle security standards IEEE 1609.2 and ETSI 102941-v1.1.1. Specifically, each vehicle v i Initially, each vehicle was equipped with a basic identifier (ID) distributed by the vehicle management department. i As a key aspect of vehicle registration with a CA, the CA generates a public key (PK) for the vehicle. i Private key SK i and kana And provide a certificate containing an asymmetric RSA signature for each pseudonym. This information is then encrypted using RSA and sent to the vehicle. Before V2V communication and message transmission, the vehicle communicates with the alias... The corresponding private key SK i The messages are digitally signed using RSA. To enable message verification, each sent message is appended with a pseudonym matching the signer's name. Corresponding certificates Receiving the vehicle must be done by using the CA public key PK. CA examine The signature in the file is checked and all other necessary fields are verified to be valid. Is it a valid kana?

[0035] Step 3) Determine the density of the neighboring areas for each vehicle:

[0036] Each vehicle v i The pseudonym used during the journey satisfy At that time, based on the nearest roadside unit r d Get the current neighbor region Number of vehicles inside Calculate v i Neighbor density And judge Is it true? If so, then For high-density areas, and use pseudonyms Add to the pre-swapping kana set Then, proceed to step (4); otherwise, For low-density regions, step (5) is performed, where d∈M;

[0037] In this step, the density of the vehicle's neighborhood is... The calculation formula is as follows:

[0038]

[0039] Based on vehicle v i Neighbor density This approach divides the area into zones and then selects a suitable pseudonym change scheme for each zone. This design is applicable not only to scenarios with high vehicle density but also to protecting vehicle location privacy in low-density scenarios. Furthermore, based on the high vehicle density in high-density areas, a set of individuals willing to change their pseudonyms is established. By selecting collaborators for pseudonym exchange, the application cost for pseudonyms can be reduced, while the degree of pseudonym confusion can be increased, thereby improving the location privacy protection capability in high-density areas. Based on the sparse vehicle characteristics in low-density areas, in step 5), the vehicle itself can use the SRNG random algorithm to select one of the two schemes to execute, which can also achieve the effect of improving pseudonym confusion, thereby improving the location privacy protection capability in low-density areas.

[0040] Step 4) Vehicles exchange pseudonyms in high-density areas:

[0041] Step 4a) When the set When the number of elements in a vector is greater than 1, the neighbor density is high for each vehicle v. n Select The pseudonym in vehicle v m Vehicle vn Using private key SK n For pseudonym certificates Perform the signature and obtain the signature result σ. n 'and include a timestamp t n ′, then use vehicle v m public key PK m Information encrypt and generate message ω n ′ and send to v m Where n≠m, and readyflag is a pre-exchange tag;

[0042] In this step, not all vehicles in v i Vehicles within the same neighborhood are willing to exchange pseudonyms, therefore a set is used. The vehicles that are willing to be exchanged are pre-loaded into the communication message, and the readyflag tag is attached to confirm that both parties are in the handshake phase and ready to exchange pseudonyms.

[0043] Step 4b) Vehicle v m Using private key SK m Decrypt ω n 'Get δ n Then use the public key to PK. n Verify signature σ n ′;If v m Agree with vehicle v n Cooperation, v m Using private key SK m For pseudonym certificates Perform the signature and obtain the signature result σ. m 'and include a timestamp t m Then use vehicle v n public key PK n Information encrypt and generate message ω m ′ and send to v n ;

[0044] In this step, vehicle v m Use private key SK m For the certificate Perform RSA signing and attach a timestamp. m ' is for the receiving vehicle v n It can be verified that the message comes from the sender v. m Whether the certificate information is accurate, authentic, and untampered with, and whether the information is accurate. m Using RSA encryption provides a secure communication channel for both parties to cooperate, protecting them from eavesdropping by malicious adversaries.

[0045] Step 4c) Vehicle v nUsing private key SK n Decrypt ω m 'Get δ m Then use the public key to PK. m Verify signature σ m ′;v n Using private key SK n For kana and certificates The signature result σ is obtained by performing the signature. n "and include a timestamp t" n "Then use vehicle v" m public key PK m Information Encrypt the message ω n "and sent to v m ;

[0046] In this step, the same as in step 4b) vehicle v n The method of first using RSA digital signature and then RSA encryption is adopted to ensure the accuracy and security of transmitted information. The ultimate purpose of attaching pseudonyms is to protect the vehicle's identity. i Get v j kana Vehicle v j Get v i kana

[0047] Step 4d)v m Using private key SK m Decrypt ω n "Get δ" n Then use the public key to perform a PK. n Verify signature σ n ", and the obtained v n kana Change to your own pseudonym; v m Using private key SK m For kana and certificates The signature result σ is obtained by performing the signature. m "and include a timestamp t" m "Then use vehicle v" n public key PK n Information Encrypt the message ω m "and sent to v n ;

[0048] In this step, vehicle v m Using his pseudonym Change to

[0049] Step 4e) Vehicle v n Using private key SK n Decrypt ω m "Get δ" m Then use the public key to perform a PK. n Verify signature σ m ", and the obtained v m kana Change to your own pseudonym, and cooperate with vehicle v m At the same time, a period of silence will begin.

[0050] In this step, vehicle v n Using his pseudonym Change to

[0051] Step 5) Obtain the pseudonym change results for vehicles in low-density areas:

[0052] Step 5a) Each vehicle v with a neighbor density of low density h For the random result x generated using the SRNG random algorithm s+1 Perform modulo-2 operations and determine whether the number of choices g obtained from the modulo-2 operation satisfies g = 0. If so, change the kana. Change to the kana for the next moment Otherwise, proceed to step (5b);

[0053] In this step, the random result x s+1 The formulas for calculating g and g are as follows:

[0054] φ(x s )→x s+1

[0055] g = x s+1 mod2

[0056] Where φ(·) is the result function of the SRNG algorithm, x s It is a secure random seed automatically generated by the SRNG algorithm.

[0057] Step 5b) Vehicle v h Use the SRNG random algorithm to generate random result x s+2 Then, for the random result x s+2 After performing a modulo-3 operation and adding one, a random silence duration γ is obtained. Then, a silence period of duration γ is entered before the kana are changed. Change to the kana for the next moment

[0058] In this step, the random result x s+2 And γ, the calculation formulas are as follows:

[0059] φ(x s′ )→x s+2

[0060] γ = (x s+2 mod 3) + 1

[0061] where x s′ is a secure random seed automatically generated by the SRNG algorithm.

Claims

1. A pseudonym changing method based on neighbor density in a vehicle-to-everything environment, comprising: Comprising the steps of: (1) initializing the vehicle networking system: An initialization of a vehicular networking system including a central authority CA, I vehicles V = {v1, v2, …, v i ,…v I} and M road side units R = {r1, r2, …, r m ,…r M} is assumed; each vehicle v i submits a registration request req{ID i} with a real identity ID i to the authority CA, the time interval between two pseudonym changes is , the minimum stable time of a pseudonym is τ, a circular region D i with radius R i is the neighbor region of a vehicle v i , a dynamic set of vehicle pseudonyms to be exchanged in D i is denoted as the pre-exchange pseudonym set , the density threshold is ρ0, where I ≥ 2, M ≥ 2, v i denotes the i-th vehicle, r m denotes the m-th road side unit, (2) the central authority generates a key and pseudonym for each vehicle and signs the pseudonym: The centrally authorized agency CA passes through each vehicle v i Registration request req{ID i }for v i After verifying the identity of each vehicle, v i Generate public key PK i Private key SK i and the current time's kana Use your own private key SK CA For kana Sign the document to obtain a pseudonym certificate. (3) judging the density of the neighbor area of each vehicle: Each vehicle v i The pseudonym used during the journey satisfy At that time, based on the nearest roadside unit r d Get the current neighbor region Number of vehicles inside Calculate v i Neighbor density And judge Is it true? If so, then For high-density areas, and use pseudonyms Add to the pre-swapping kana set Then… proceed to step (4), otherwise, For low-density regions, step (5) is performed, where d∈M; (4) vehicles exchange pseudonyms in high-density areas: (4a) When the set When the number of elements in a vector is greater than 1, the neighbor density is high for each vehicle v. n Select The pseudonym in vehicle v m Vehicle v n Using private key SK n For pseudonym certificates Perform the signature and obtain the signature result σ. n 'and include a timestamp t n ′, then use vehicle v m public key PK m Information encrypt and generate message ω n ′ and send to v m Where n≠m, and readyflag is a pre-exchange tag; (4b) vehicle v m with private key SK m decrypt ω n to get δ n , then with public key PK n verify signature σ n '; if v m agrees to cooperate with vehicle v n , v m signs the pseudonym certificate with private key SK m to get signature result σ m ' and attaches time stamp t m ', then encrypts the information with public key PK n of vehicle v n to get message ω m ' and sends to v n ; (4c) vehicle v n with the private key SK n decrypt ω m to get δ m , and with the public key PK m verify the signature σ m ; v n with the private key SK n sign the pseudonym and the certificate to get the signature result σ n " and attach the timestamp t n ", then encrypt the information with the public key PK m of the vehicle v m to get the message ω n " and send it to v m ; (4d)v m with the private key SK m decrypt ω n get δ n with the public key PK n verify the signature σ n and get the v n change the pseudonym of v to his own; v m sign the pseudonym and the certificate with the private key SK m to get the signature σ m and attach the time stamp t m , then encrypt the information with the public key PK n of the vehicle v n to get the message ω m and send it to v n ; (4e) vehicle v n with the private key SK n decrypt ω m get δ m with the public key PK n verify the signature σ m and get the v m pseudonym change to his own pseudonym and cooperate with the vehicle v m at the same time enter a period of silence ε; (5) get the pseudonym change result of low-density area vehicles: (5a) each vehicle v whose neighbor density is low density h a random result x generated using the SRNG random algorithm s+1 a modulo-2 operation is performed, and it is determined whether the selected number of schemes g obtained by the modulo-2 operation satisfies g = 0, and if so, the pseudonym is changed to the pseudonym of the next time Otherwise, step (5b) is executed; (5b) vehicle v h a random result x is generated using the SRNG random algorithm s+2 , then a modulo three operation is performed on the random result x s+2 , one is added to the result, and a random silence duration γ is obtained, and then the pseudonym is changed to the pseudonym 2.The pseudonym changing method based on neighbor density in a V2X environment according to claim 1, wherein, the neighbor density described in step (3) The formula for calculating it is: 3.The pseudonym changing method based on neighbor density in a V2X environment according to claim 1, wherein, The random result x in step (5a) s+1 and g, the calculation formula is respectively: φ(x s )→x s+1 g = x s+1 mod2 where φ(·) is the result function of the SRNG algorithm, x s is a secure random seed. 4.The pseudonym changing method based on neighbor density in a V2X environment according to claim 1, wherein, The random result x in step (5b) s+2 and γ, the calculation formula is respectively: φ(x s′ )→x s+2 y = (x s+2 mod 3) + 1 where x s′ is a secure random seed.

Images