Efficient kana dynamic updating method based on neighbor cooperation algorithm in Internet of Vehicles environment

Abstract

The invention provides an efficient kana dynamic updating method based on a neighbor cooperation algorithm in an Internet of Vehicles environment, and belongs to the technical field of Internet of Vehicles safety. The technical problems of high communication overhead and large storage burden of the pseudonym updating scheme caused by strong vehicle mobility and infrastructure dependence in the Internet of Vehicles environment are solved. According to the technical scheme, the method comprises the following steps that S1, a system is initialized; s2, bidirectional identity authentication; s3, generating and updating a short pseudonym; s4, maintaining a neighbor vehicle list; s5, exchanging temporary pseudonyms; and S6, updating the vehicle-pseudonym mapping. The problem of infrastructure dependence caused by frequent communication between the vehicles and the RSU in an existing pseudonym updating scheme is effectively solved, flexible pseudonym exchange between the vehicles is achieved, meanwhile, on the premise that multiple safety requirements of identity privacy protection, pseudonym non-relevance and the like are met, the number of pre-stored pseudonyms and the pseudonym exchange frequency are effectively reduced, and the probability of pseudonym exchange is lowered. And the storage and communication overhead is relatively low.

Description

Technical Field

[0001] The present invention relates to the technical field of Internet of Vehicles security, and particularly to an efficient pseudonym dynamic update method based on neighbor cooperation algorithm in the Internet of Vehicles environment. Background Art

[0002] The Internet of Vehicles (IoV), as a typical application of the Internet of Things in the transportation field, realizes information sharing through vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I), and vehicle-to-person (V2P) communications. The market scale of the Internet of Vehicles is growing rapidly. According to the "China Internet of Vehicles Industry Market Panorama Research and Development Prospect Forecast Report (2024 - 2029)", it is predicted that the market penetration rate of the Internet of Vehicles in China will exceed 75% in 2025, and the user scale will exceed 380 million vehicles. However, the unencrypted beacon messages (such as BSM) in the open wireless channel make the vehicle identity and location information vulnerable to being stolen, leading to the risk of privacy leakage. For example, Volkswagen Group once exposed the trajectory information of 800,000 electric vehicle users due to software vulnerabilities. Therefore, the identity privacy issue is a major hidden danger in the security of the Internet of Vehicles.

[0003] Regarding the problem of identity privacy leakage, the vehicle pseudonym mechanism is the core solution. By periodically changing the vehicle identifier, the pseudonym mechanism can effectively prevent the long-term tracking of vehicle identities. Early pseudonym generation and distribution mainly relied on infrastructure or pre-allocated pseudonym pools. For example, in the literature "CREASE: Certificateless and REused-pseudonym based Authentication Scheme for Enabling security and privacy in VANETs", a pre-allocated pseudonym pool was used, and the RSU coordinated the synchronous update of pseudonyms. However, this scheme has the problems of high storage requirements for the pseudonym pool and a high degree of dependence on the RSU. To reduce storage overhead and prevent attackers from tracking pseudonyms through movement trajectory prediction, the literature "Broadcast and silence period (bsp): A pseudonym change strategy" proposed a strategy for updating pseudonyms during the broadcast and silence period. Vehicles select hybrid areas to broadcast and be silent periodically, and change pseudonyms during the silent phase. To achieve traceability of identities while hiding the true identities of vehicles, the literature "CPAHP: Conditional privacy-preserving authentication scheme with hierarchical pseudonym for 5G-enabled IoV" combined the hierarchical pseudonym mechanism with elliptic curve encryption and blockchain technology to achieve pseudonym updates. When a vehicle enters the coverage area of different micro base stations, it generates new communication pseudonyms, and only the vehicle and the trusted authority TA know the true identity of the vehicle. Although the above schemes fully consider optimizing storage and communication overheads and resisting trajectory tracking attacks in pseudonym allocation and update, they all fail to get rid of the dependence on infrastructure, and have defects such as poor scalability, high latency, and high single-point failure risk. Therefore, the literature "A comprehensive pseudonym changing scheme for improving location privacy in vehicular networks" further proposed a context-aware and traffic-adaptive pseudonym change scheme. The RSU only coordinates the pseudonym change of vehicles within the region, triggers synchronous changes based on traffic patterns and vehicle context, and the vehicles dynamically generate pseudonyms. Although the scheme does not require pre-allocation of a fixed pool, it still requires the RSU to coordinate synchronous updates, and does not completely solve the problem of dependence on infrastructure.The literature "A privacy conserves pseudonym acquisition scheme in vehicular communication systems" proposes a single-pseudonym-derived multi-sub-pseudonym scheme based on encrypted identities, allowing vehicles to autonomously generate multiple sub-pseudonyms from a single pseudonym and cooperate with neighboring vehicles to determine the pseudonym update time. However, this scheme has the problem that long-term use of the same root pseudonym is vulnerable to correlation attacks, resulting in the failure of privacy protection. It can be seen that the early pseudonym update schemes still have many deficiencies in terms of security and scalability.

[0004] To address the above problems, researchers have proposed a pseudonym exchange mechanism. This mechanism dynamically obfuscates identity information through cooperation between vehicles, enabling the reuse of the same pseudonym by multiple vehicles during a communication period. This mechanism based on dynamic group identity obfuscation only requires a small number of pseudonyms to build an efficient privacy protection system, significantly reducing the demand for the pseudonym pool capacity. For example, the literature "PAPU: Pseudonym swap with provable unlinkability based on differential privacy in VANETs" proposes a pseudonym exchange scheme with provable unlinkability, ensuring location and identity privacy by exchanging pseudonyms. However, the scheme relies too much on RSU coordination, limiting its application scope. The literature "DPSP: A Dynamic Pseudonym Swap Program Based Location Privacy Protection Algorithm for Internet of Vehicles" proposes a dynamic pseudonym exchange scheme based on fog computing, managing pseudonyms through the fog layer to reduce latency and dynamically triggering pseudonym exchange using vehicle communication time and regional vehicle density. However, the scheme also has the problem of relying on the fog layer RSU. To avoid the dependence of the scheme on infrastructure, the literature "Security compliant and cooperative pseudonyms swap for location privacy preservation in VANETs" proposes an infrastructure-independent pseudonym exchange scheme. The trusted authority TA loads each vehicle with a non-exchangeable pseudonym and a set of exchangeable pseudonyms. When the usage threshold is reached, the non-exchangeable pseudonym is used to safely exchange its exchangeable pseudonyms without the participation of the RSU in the pseudonym exchange process. However, only one pseudonym in the pseudonym pool can be exchanged in a single exchange in the scheme, resulting in low efficiency.

[0005] Although the above research has achieved identity privacy protection to some extent in the vehicle networking environment, there are still problems such as high communication overhead, large storage burden, and infrastructure dependence. In order to reduce the dependence of vehicles on infrastructure, while reducing the number of pre-stored pseudonyms and lowering communication costs, the present invention proposes an efficient pseudonym dynamic update scheme for vehicle networking based on a neighbor cooperation algorithm. To reduce the dependence of pseudonym update on RSU, the scheme designs a decentralized neighbor cooperation algorithm to achieve pseudonym exchange between vehicles without infrastructure dependence. At the same time, a vehicle short pseudonym autonomous generation algorithm is designed, which effectively reduces the number of pre-stored pseudonyms, improves the efficiency of pseudonym generation, significantly reduces storage costs and communication overhead, greatly improves the efficiency of pseudonym update, and is applicable to high-dynamic vehicle networking environments.

[0006] Based on a full investigation of the defects of the current vehicle pseudonym update related technologies in the vehicle networking environment, the present invention proposes an innovative scheme based on a neighbor cooperation algorithm. The scheme uses relevant technologies such as hash functions and the basic safety message BSM of vehicle networking. To clearly explain the principle and steps of the present invention, the relevant background knowledge is first elaborated:

[0007] (1) Elliptic curves

[0008] Definition of elliptic curves: Define the elliptic curve equation E as y 2 = x 3 + ax + b (mod q), and Δ = 4a 3 + 27b 2 ≠ 0 (mod q), a, b ∈ F, where F is a finite field with order of large prime number q.

[0009] Addition of elliptic curves: Assume there are two different points P and Q on the elliptic curve, and the result of their addition operation is R, that is, P + Q = R. By connecting the line of P and Q and finding the intersection of the line and the curve, and then obtaining R by taking the x-axis symmetry of the intersection. If the two points are the same, the addition operation needs to perform a tangent operation, that is, by finding the tangent of the curve at this point, then finding the intersection with the curve, and taking the x-axis symmetry to obtain the result.

[0010] Point multiplication of elliptic curves: From the point doubling formula, it can be known that P + P + P + … + P = k × P. In the elliptic curve, the point multiplication operation is also called the point doubling operation, and the mathematical description is: Q = k × P, where P, Q are points on the elliptic curve, k is an integer, and k cannot be greater than the order of P.

[0011] (2) Related difficult problems and their assumptions

[0012] Elliptic Curve Discrete Logarithm Problem (ECDLP): Given a point P on an elliptic curve E, adding P to itself k times results in a point Q, i.e., the point Q satisfies the relation Q = k × P, where The elliptic curve discrete logarithm problem means that given P and Q, it is difficult for any probabilistic polynomial-time (PPT) algorithm to find k.

[0013] (3) One-way hash function

[0014] A one-way hash function, also known as a hash function, can transform an input value of any length into an output value of a fixed length, and this output value is called the hash value. A one-way hash function has the following properties:

[0015] 1) Collision resistance: That is, it is very difficult to find two different messages with the same hash value, i.e., it is difficult to find two different inputs m1 and m2 such that H(m1) = H(m2).

[0016] 2) One-wayness: The property that the message cannot be calculated back from the hash value, i.e., given the hash value H(m), it is difficult to find m.

[0017] (4) Basic Safety Message BSM

[0018] The Basic Safety Message (BSM) is one of the core message types for vehicle-to-vehicle communication and is used for vehicles to periodically and real-time exchange status information through broadcasting. Taking the SAE J2735 standard defined by the Society of Automotive Engineers in the United States as an example, its structure is shown in Table 1:

[0019] Table 1 Basic Safety Message Structure

[0020]

[0021] The BSM consists of two parts: core data and extended data. Among them, the core data are mandatory fields, including the MessageFrame field and the CoreData field. The MessageFrame field is the message frame header, which contains the message type identifier, timestamp, message priority, and message transmission mode. The CoreData field contains vehicle status data, such as location, speed, driving direction, vehicle pseudonym identifier, etc. The extended data are optional fields that can be added to the BSM according to actual needs. For example, the VehicleSize field describes the vehicle size, and the VehicleClassification field describes the vehicle classification. The VehicleExtensions field is a supplementary extension that allows customizing data based on the standard BSM to achieve customized functions. Summary of the Invention

[0022] The present invention provides an efficient pseudonym dynamic update method based on neighbor cooperation algorithm in the vehicle networking environment, aiming to achieve infrastructure-independent pseudonym exchange through the neighbor cooperation algorithm, and at the same time rely on the autonomous generation of short vehicle pseudonyms to reduce the number of pre-stored pseudonyms and lower the pseudonym exchange frequency, thereby reducing storage costs and communication overhead.

[0023] For ease of understanding, first, the symbols and their meanings involved in the present invention are given as shown in Table 2 below:

[0024] Table 2

[0025]

[0026]

[0027] The present invention is implemented by the following measures: An efficient pseudonym dynamic update method based on neighbor cooperation algorithm in the vehicle networking environment includes the following steps:

[0028] S1. System initialization;

[0029] S2. Two-way identity authentication;

[0030] S3. Short pseudonym generation and update;

[0031] S4. Neighbor vehicle list maintenance;

[0032] S5. Temporary pseudonym exchange;

[0033] S6. Vehicle-pseudonym mapping update.

[0034] Furthermore, the S1 step includes:

[0035] S11. Input the system security parameter λ. The Trusted Authority (TA) generates a large prime number q, selects parameters a and b in the prime field F q and generates an elliptic curve E: y 2 = x 3 + ax + b (mod q), which needs to satisfy: Δ = 4a 2 + 27b 2 ≠ 0 (mod q). Select an additive cyclic group G on the elliptic curve with order q and a generator P;

[0036] S12. In the multiplicative cyclic group of integers with order q - 1 , TA selects a random number s as the private key SK of the trusted authority TA and calculates the public key PK of the trusted authority according to the double - point operation of the elliptic curve TA = s × P;

[0037] S13. Select two secure hash functions:

[0038]

[0039] H2: {0, 1} * → G;

[0040] S14. TA publishes the system parameters params = {G, q, P, H1, H2, PK TA}.

[0041] S15. The Road Side Unit (RSU) registers. TA completes the registration for the RSU, assigns an identity identifier to the RSU, generates a public key, a private key, and issues a certificate;

[0042] S151. TA selects a random number as the private key j of the Road Side Unit R and calculates the public key j of R

[0043] S152. TA assigns a unique identity identifier j to R and issues a certificate The certificate contains information such as the signature of TA;

[0044] S153. TA sends to R j through a secure channel;

[0045] S16. The vehicle registers. TA completes the registration for the vehicle, assigns an identity identifier to the vehicle, generates a public key, a private key, a secret value, a long pseudonym, and issues a long pseudonym certificate;

[0046] S161. TA selects a random number as the private key of vehicle V i Calculate the public key V i

[0047] S162. TA assigns a unique identity identifier i secret value k to V i , long vacation name PID i , and issues a long vacation name certificate The certificate contains PID i , TA's signature and other information;

[0048] S163. TA establishes a Vehicle - Pseudonym Mapping Table (VPMT), and stores the PID i of V i , k i field information into the mapping table. The temporary pseudonym TID i and the temporary pseudonym private key are initially empty, establishing the mapping between the vehicle and the temporary pseudonym. Among them, the structure of the vehicle - pseudonym mapping table VPMT is shown in Table 3. The fields of each record are in turn: vehicle identity identifier, long vacation name, secret value, temporary pseudonym, temporary pseudonym private key. The main function of this table is to achieve the identity traceability of malicious vehicles.

[0049] Table 3 Vehicle - Pseudonym Mapping Table

[0050]

[0051] S164. TA sends k i , PID i , to V i through a secure channel, and V i stores the information in the on - vehicle unit OBU.

[0052] Furthermore, the S2 step includes:

[0053] S21. R j periodically broadcasts a message within its broadcast domain where TS is the timestamp, and signature indicates signing the message with ;

[0054] S22. V i ​​​​Receive the message, check the validity of the TS, and then obtain from and verify σ1 to ensure the identity legality of R j j

[0055]

[0055] S23, V i Use to generate construct and send it to R j where indicates encrypting the message with

[0056] S24, R j After receiving the message, decrypt the message with Check the validity of the TS after decryption, and then obtain from and verify σ2 to ensure the identity legality of V i i

[0057]

[0057] S25, R j Select a random number as the temporary pseudonym private key of V i i Calculate the temporary pseudonym TID of V i i i = p i × P;

[0058] S26, R j Use to generate construct an encrypted message and send it to V i i

[0059] S27, R j Construct an encrypted message and send it to TA;

[0060] S28, After receiving the message, TA uses SK TA to decrypt and verify the timeliness of the message according to the TS. If the verification passes, TA further verifies σ3 to ensure the legality of the message. After the verification passes, update TID i to the row where PID i is stored in the vehicle-pseudonym mapping table to achieve the identity traceability of malicious vehicles.

[0061] Furthermore, the S3 step includes:

[0062] S31, V i Receive the message sent by R j j After that, use to decrypt, and perform validity verification according to TS. After the verification passes, further verify σ3 to ensure the legality of the message. Finally, TID i is stored in the OBU;

[0063] S32, V i Calculate the transition value Calculate and generate the first short kana private key SK i,1 = H1(M i,1 ) and the first short kana SID i,1 = SK i,1 × P;

[0064] S33. After using the short kana for a period of time, V i autonomously updates the short kana, calculates M i,k = H2(M i,k-1 ), calculates and generates the kth short kana private key SK i,k = H1(M i,k ) and the corresponding short kana SID i,k = SK i,k × P.

[0065] Furthermore, the S4 step includes:

[0066] S41, V i Periodically broadcast the basic safety message BSM;

[0067] S411, V i Expand the optional fields of the BSM, define the pseudonym exchange flag RTS and the synchronous pseudonym update flag PSR. Among them, the RTS flag is used to indicate whether the vehicle's current state allows pseudonym exchange. If its value is 1, it means yes; if its value is 0, it means the vehicle is in the process of updating or exchanging pseudonyms; the PSR flag is default set to 0. If its value is 1, it means the requesting vehicle has completed the temporary pseudonym exchange and the neighbor vehicles need to synchronously update the short kana;

[0068] S412, V i Periodically broadcast the BSM. At time t, V i broadcasts the BSM that contains SID i,m , position POS i,t , speed VEL i,t , driving direction H i,t , timestamp TS, RTS i,t and PSR i,t and other information;

[0069] S42, V i According to the received neighbor vehicle Vj The BSM of i,t ;

[0070] S421, V i Receives the BSM message of V j and first checks whether the RTS in the message is 1, and whether H j,t is consistent with H i,t to determine whether it currently supports pseudonym exchange. If not, V j,t further determines whether the short pseudonym SID of V i is within N j and deletes the short pseudonym if it exists. If so, go to step S422; j,n i,t i j

[0071] S422, V i Calculates the distance d j from V i,j,t = |POS j,t - POS i,t | and compares it with the neighbor distance standard d0. If d i,j,t is greater than d0, further determines whether SID j,n is within N i,t . If it exists, delete it; otherwise, calculate the position deviation between the two vehicles The calculation method is where the squared predicted distance SQD i,j,t+T is calculated as SQD i,j,t+T = ((POS j,t - POS i,t ) + (VEL j,t - VEL i,t ) × T) 2 ;

[0072] S423, V i Compares with the position standard deviation sd0. If is greater than sd0, determines whether SID j,n is within N i,t . If it is, delete the short pseudonym; otherwise, add the short pseudonym to N i,t .

[0073] Furthermore, the S5 step includes:

[0074] S51, V i Generates and then constructs an encrypted request message to send to V j ;

[0075] S52, V j Use SK j,n to decrypt this request message, perform time validity verification based on TS, and then perform message integrity verification based on σ4. If the verification passes, V j will store TID i and SK Ti into its own OBU;

[0076] S53, V j Generate Then construct an encrypted response message and send it to V i ;

[0077] S54, V i Use to decrypt this response message, perform time validity verification based on TS, and then perform message integrity verification based on σ5. If the verification passes, V i will store TID j and into its own OBU, and calculate to generate SK i,1 = H1(M i,1 ) and SID i,1 = SK i,1 × P, and record the pseudonym generation time as T0. If the current time T1 minus T0 is T (where T is the current pseudonym survival period), V i needs to immediately update the short pseudonym;

[0078] S55, V i Set the flag bit PSR in the BSM i,t to 1 and broadcast it to remind all neighboring vehicles to synchronize the pseudonym update;

[0079] S56, Neighboring vehicles receive the BSM from V i , first perform validity verification based on TS, and further check whether PSR i,t is 1. If PSR i,t is 1, V j calculates to generate SK j,1 = H1(M j,1 ) and SID j,1 = SK j,1 × P. At the same time, the remaining neighboring vehicles (taking the neighboring vehicle V l,k with the short pseudonym as SID l as an example) calculate M l,k+1 = H2(M l,k ), generate SK l,k+1 = H1(M l,k+1 ) and SIDl,k+1 = SK l,k+1 × P. The neighbor vehicles participating in the hiragana update respectively record T0. If T1 minus T0 is T, all neighbor vehicles need to immediately update the hiragana.

[0080] Furthermore, the step S6 includes:

[0081] S61, V i Generate Then construct an encrypted message Send it to TA;

[0082] S62, V j Generate Then construct an encrypted message Send it to TA;

[0083] S63, TA uses SK TA To decrypt V i And the message sent by V j And perform validity verification according to TS, and then complete message integrity verification according to σ6 and σ7 respectively. If all verifications pass, TA further compares the TIDs i , TID j In the vehicle-pseudonym mapping table according to PID i , PID j For retrieval, locate the corresponding temporary pseudonym and its private key And exchange the two records;

[0084] S64, if TA determines that the temporary pseudonyms sent by V i And V j Are inconsistent, it is necessary to complete the trace of the abnormal behavior. TA revokes the long pseudonym certificate of the abnormal vehicle V i Of At the same time, broadcast a warning about the identity of V i Then, TA notifies the victim vehicle V j To re-authenticate to obtain a new temporary pseudonym.

[0085] Compared with the prior art, the beneficial effects of the present invention are:

[0086] (1) An efficient pseudonym dynamic update method based on a neighbor cooperation algorithm in a vehicle networking environment of the present invention designs a decentralized neighbor cooperation algorithm. The scheme optimizes the infrastructure dependence problem existing in the existing vehicle networking pseudonym exchange scheme. Vehicles maintain a neighbor vehicle list during driving, and randomly select neighbor vehicles in the list for temporary pseudonym exchange during pseudonym exchange, realizing pseudonym exchange between vehicles without infrastructure dependence.

[0087] (2) An efficient pseudonym dynamic update method based on neighbor cooperation algorithm in the vehicle networking environment of the present invention designs a vehicle short pseudonym autonomous generation algorithm. The solution solves the problems of high storage cost of the pseudonym pool and high communication overhead of frequent pseudonym exchange in the existing vehicle networking pseudonym exchange solutions. Vehicles can use the temporary pseudonyms obtained through identity authentication during driving and, based on the hash function and ECDLP, autonomously generate short pseudonyms when needed, effectively reducing the number of pre-stored pseudonyms, improving the pseudonym generation efficiency, significantly reducing the storage cost and communication overhead, greatly improving the efficiency of pseudonym update, and being applicable to the high-dynamic vehicle networking environment.

[0088] (3) Through performance analysis, it shows that the solution of an efficient pseudonym dynamic update method based on neighbor cooperation algorithm in the vehicle networking environment of the present invention has advantages over other solutions in terms of security, storage, and communication overhead. The solution not only meets multiple security requirements such as identity privacy protection and pseudonym non-linkability but also has low storage and communication overhead, reflecting high performance and practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0089] The drawings are used to provide further understanding of the present invention and constitute a part of the specification. They are used together with the embodiments of the present invention to explain the present invention and do not constitute a limitation to the present invention.

[0090] Figure 1 It is the overall flowchart of the efficient pseudonym dynamic update method based on neighbor cooperation algorithm in the vehicle networking environment provided by the present invention.

[0091] Figure 2 It is the schematic diagram of the system architecture in the present invention.

[0092] Figure 3 It is the flowchart of the two-way identity authentication phase of the efficient pseudonym dynamic update method based on neighbor cooperation algorithm in the vehicle networking environment provided by the present invention.

[0093] Figure 4 It is the flowchart of the temporary pseudonym exchange phase of the efficient pseudonym dynamic update method based on neighbor cooperation algorithm in the vehicle networking environment provided by the present invention.

[0094] Figure 5 It is the flowchart of the vehicle-pseudonym mapping update phase of the efficient pseudonym dynamic update method based on neighbor cooperation algorithm in the vehicle networking environment provided by the present invention.

[0095] Figure 6 It is the comparison diagram of storage overhead provided by the present invention.

[0096] Figure 7 It is the comparison diagram of communication overhead provided by the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0097] To make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Of course, the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0098] Embodiment 1

[0099] Embodiment 1 provides an efficient pseudonym dynamic update method based on neighbor cooperation algorithm in the vehicle networking environment, as Figure 1 shown, which includes the following steps:

[0100] S1. System initialization;

[0101] S2. Two-way identity authentication;

[0102] S3. Short pseudonym generation and update;

[0103] S4. Neighbor vehicle list maintenance;

[0104] S5. Temporary pseudonym exchange;

[0105] S6. Vehicle-pseudonym mapping update.

[0106] As Figure 2 shown, the vehicle networking architecture in the efficient pseudonym dynamic update method based on neighbor cooperation algorithm includes: Trusted Authority (TA), Road Side Unit (RSU), and On Board Unit (OBU). The functions of each entity are as follows:

[0107] 1) Trusted Authority TA: TA is the only authoritative organization in the system that all nodes unconditionally trust. It is responsible for managing and supervising all nodes in the system, distributing public and private keys to nodes, and issuing certificates. At the same time, it constructs a vehicle-pseudonym mapping table and stores vehicle node-related information to trace malicious vehicles.

[0108] 2) Road Side Unit RSU: Distributed on both sides of the road, as a fixed communication node in the vehicle networking, it is responsible for allocating temporary pseudonyms to vehicle nodes, and at the same time, as a relay node, it provides a communication connection method for vehicles and the trusted authority.

[0109] 3) On Board Unit OBU: Installed inside the vehicle, the vehicle establishes communication with other entities through the OBU. Privacy messages such as the vehicle's private key, secret value, pseudonym, and pseudonym certificate are stored in the tamper-proof module of the OBU.

[0110] As Figure 3 shown, the specific content of S2 includes the following steps:

[0111] S21. R jPeriodically broadcast messages within its broadcast domain

[0112] S22, V i Receive the message, check the validity of the TS, and then obtain from and verify σ1 to ensure the identity legitimacy of R ; j The identity legitimacy of;

[0113] S23, V i Use Generate Construct an identity authentication request message And send it to R j ;

[0114] S24, R j After receiving the message, decrypt the message with Check the validity of the TS after decryption, and then obtain from and verify σ2 to ensure the identity legitimacy of V ; i The identity legitimacy of;

[0115] S25, R j Select a random number As the temporary pseudonym private key of V i Calculate the temporary pseudonym TID of V Calculate V i Temporary pseudonym TID i = p i × P;

[0116] S26, R j Use Generate Construct an encrypted message And send it to;

[0117] S27, R j Construct an encrypted message And send it to TA;

[0118] S28, After receiving the message, TA uses SK TA Decrypt it, and verify the timeliness of the message according to the TS. If the verification passes, TA further verifies σ3 to ensure the legitimacy of the message. After the verification passes, it will TID i Update and store it in the row of the vehicle-pseudonym mapping table where PID i is located to achieve the identity traceability of malicious vehicles.

[0119] Such as Figure 4 shown, the specific content of the S5 includes the following steps:

[0120] S51, V i Generate Then construct an encrypted request message Send it to V j ;

[0121] S52, V j Use SK j,n To decrypt this request message, perform time validity verification based on TS, and then perform message integrity verification based on σ4. If the verification passes, V j Will store TID i And Into its own OBU;

[0122] S53, V j Generate Then construct an encrypted response message Send it to V i ;

[0123] S54, V i Use To decrypt this response message, perform time validity verification based on TS, and then perform message integrity verification based on σ5. If the verification passes, V i Will store TID j And Into its own OBU, and calculate To generate SK i,1 = H1(M i,1 ) and SID i,1 = SK i,1 × P, and record the pseudonym generation time as T0. If the current time T1 minus T0 is T (where T is the current pseudonym survival period), vehicle V i Needs to immediately update the short pseudonym;

[0124] S55, V i Set the flag bit PSR in the BSM i,t To 1 and broadcast it to remind all neighboring vehicles to synchronize pseudonym updates;

[0125] S56, Neighboring vehicles receive the BSM of V i First, perform validity verification based on TS, and further check whether PSR i,t Is 1. If PSR i,t Is 1, V j Calculate To generate SK j,1 = H1(M j,1 ) and SID j,1 = SK j,1 × P. At the same time, the other neighboring vehicles (the neighboring vehicle V with the short pseudonym as SID l,k ) ofl Calculate M (taking [example] as an example) l,k+1 = H2(M l,k ), and generate SK l,k+1 = H1(M l,k+1 ) and SID l,k+1 = SK l,k+1 ×P. The neighbor vehicles participating in the hiragana update respectively record T0. If T1 minus T0 is T, all neighbor vehicles need to immediately update the hiragana.

[0126] As Figure 5 shown, the specific content of the said S6 includes the following steps:

[0127] S61, V i Generate Then construct an encrypted message and send it to TA;

[0128] S62, V j Generate Then construct an encrypted message and send it to TA;

[0129] S63, TA decrypts the messages sent by V TA and V i using SK j , and completes the validity verification according to TS. Then, it respectively completes the message integrity check according to σ6 and σ7. If all verifications pass, TA further compares the TID i , TID j in the two messages to see if they are the same. If they are consistent, TA retrieves in the vehicle-pseudonym mapping table according to PID i , PID j to locate the corresponding temporary pseudonym and its private key and exchanges the two records;

[0130] S64, if TA determines that the temporary pseudonyms sent by V i and V j are inconsistent, it is necessary to complete the trace of the abnormal behavior. TA revokes the long pseudonym certificate i of the abnormal vehicle V and at the same time broadcasts a warning about the identity of V i . Then, TA notifies the victim vehicle V j to re-authenticate to obtain a new temporary pseudonym.

[0131] To verify the feasibility of this embodiment, the security of this embodiment 1 is analyzed:

[0132] Security goals and attack models:

[0133] 1. The security goals of the scheme are as follows:

[0134] a) Resistance to replay attacks: A replay attack means that, in order to disrupt the normal communication and pseudonym exchange of vehicles, a malicious attacker resends previously intercepted messages to deceive other vehicles. An effective pseudonym exchange scheme should have the function of preventing replay attacks to ensure the uniqueness and non-repeatability of messages during the pseudonym exchange process.

[0135] b) Resistance to forgery attacks: A forgery attack refers to a malicious attacker forging the vehicle identity to conduct pseudonym exchange with other vehicles in order to obtain the identity information of other vehicles. In this scheme, by using a long pseudonym signature during the temporary pseudonym exchange, it is ensured that only legitimate vehicles can conduct pseudonym exchange, thereby preventing forgery attacks.

[0136] c) Identity privacy protection: During the communication process, it is necessary to protect the identity privacy of vehicles to prevent attackers from obtaining their true identities by tracking the communication behaviors of vehicles. In addition, when the malicious behavior of a vehicle is discovered, the trusted authority TA can trace the true identity of the vehicle to avoid it continuing to endanger the system security.

[0137] d) Unlinkability of pseudonyms: After the vehicle pseudonym is updated, the attacker cannot associate the previous and the current pseudonyms with the same vehicle, that is, cannot link the new pseudonym of the vehicle with the old one.

[0138] 2. The attack model is defined as follows:

[0139] First, the following entities are defined: Challenger C, responsible for system initialization, pseudonym generation, temporary pseudonym exchange, and responding to adversary queries; Adversary A, who can initiate pseudonym generation requests, eavesdrop on temporary pseudonym exchange messages, but cannot obtain the master private key SK of TA TA and the vehicle secret value k i .

[0140] The security proof process of the scheme is executed through a game between adversary A and challenger C.

[0141] Definition 1 (Indistinguishability under chosen-plaintext attack): If the probability that the adversary wins the game is negligible within polynomial time in probability, the scheme is said to satisfy indistinguishability under chosen-plaintext attack.

[0142] Security analysis:

[0143] Lemma 1 Under the random oracle model and the ECDLP hard problem, this embodiment can achieve the indistinguishability of short pseudonyms under chosen-plaintext attack.

[0144] Proof Assume that there is an adversary A who can, within polynomial time, with a non-negligible advantage, determine the association between the vehicle short pseudonym and the vehicle identity. Then an algorithm B can be constructed to use adversary A to solve the ECDLP hard problem and reverse-derive the original value of the hash function.

[0145] Challenger C plays the following game with adversary A:

[0146] (1) System initialization: Challenger C inputs the system security parameter λ, outputs (G, q, P, H1, H2), selects a random number and computes PK TA = s × P. Finally, Challenger C sends the system public parameters params = {G, q, P, H1, H2, PK TA} to adversary A.

[0147] (2) Query phase, adversary A makes the following polynomially bounded number of queries:

[0148] Temporary pseudonym generation query phase, adversary A requests to generate a temporary pseudonym for vehicle PID i , and Challenger C generates it and returns it to adversary A. The specific steps are as follows:

[0149] a) Challenger C creates a list L pk , initially empty, with the element type being

[0150] b) Adversary A requests a query about PID i ;

[0151] c) Challenger C queries L pk . If it exists then directly respond TID i to A;

[0152] d) If it does not exist, then Challenger C randomly selects lets TID i = p i × P. Then it stores into L pk and responds TID i to adversary A.

[0153] Short pseudonym generation query phase, adversary A requests to generate a short pseudonym for PID i , and Challenger C generates it and returns it to adversary A. The specific steps are as follows:

[0154] a) Challenger C creates a list L SID , initially empty, with the element type being

[0155] b) Adversary A requests a short pseudonym generation query about PID i ;

[0156] c) Challenger C queries L SID, if there exists then randomly select as the original M i the hash value obtained through H2, as the new M i the hash value obtained through H1, calculate SID i = SK i '×P, and update the elements in the list, and finally respond with SID i to the adversary A;

[0157] d) If not, the challenger C obtains the element regarding PID pk from L i randomly select as the hash value obtained through H2, as M i the hash value obtained through H1, calculate SID i = SK i '×P, then store it in L SID and respond with SID i to the adversary A.

[0158] (3) Challenge phase: The challenger C selects vehicle PIDs 0 and 1, and queries L pk , L SID , update the temporary pseudonym pairs of PIDs 0 and 1 in the exchange list and Finally, the challenger C randomly selects b ∈ {0, 1}, and regenerates the short pseudonym SID b for PID b and returns it to the adversary A.

[0159] (4) Guess phase: The adversary A receives SID b and determines whether it belongs to PID0 or PID1, and outputs the guess result b'.

[0160] In the above game, if the adversary A can make b' = b with a non-negligible advantage, that is, the adversary A determines whether SID b belongs to PID0 or PID1, according to the challenge definition, the adversary A needs to guess belongs to the vehicle PID b , then the algorithm B can reverse infer b from SID and thus solve the ECDLP instance and reverse infer the original value of the hash function, which contradicts the ECDLP problem and the one-way property of the hash function.

[0161] Therefore, the advantage of the adversary A where Denote the advantage of algorithm B in solving the ECDLP hard problem as q h which is the number of hash queries, and l s is the output length of the hash function. Then this advantage is negligible. Therefore, adversary A cannot determine whether the short pseudonym SID b belongs to PID0 or PID1, that is, the short pseudonyms generated by the proposed scheme in this paper are indistinguishable under the attack of adversary A. Q.E.D.

[0162] Theorem 1 This embodiment can achieve anti-replay attack for temporary pseudonym exchange

[0163] Proof In this embodiment, timestamps TS are attached to the messages during temporary pseudonym exchange. For example, the temporary pseudonym exchange request message Since timestamps are attached every time during temporary pseudonym exchange, the receiver will verify the timestamps. If the verification fails, the current pseudonym exchange will terminate. Therefore, this embodiment can resist replay attacks. Q.E.D.

[0164] Theorem 2 This embodiment can achieve anti-forgery attack for temporary pseudonym exchange

[0165] Proof In an open-channel environment, an attacker will forge a legitimate vehicle V i or an RSU. During temporary pseudonym exchange, when the vehicle sends a request message or a response message, it needs to attach the signature σ of the vehicle's long pseudonym to the message. Since a fake vehicle cannot obtain the private key i assigned by the TA to the legitimate vehicle V Therefore, a fake vehicle cannot attach a legitimate signature to the message during the pseudonym exchange process, and thus cannot carry out a forgery attack. In this embodiment, since the RSU does not participate in the pseudonym exchange, a fake RSU cannot interfere with the pseudonym exchange process. Therefore, this embodiment can resist forgery attacks. Q.E.D.

[0166] Theorem 3 This embodiment can achieve identity privacy protection for vehicles.

[0167] Proof In this embodiment, each time a vehicle travels, it needs to use its long pseudonym identity PID i to authenticate its identity within the communication domain of the first RSU and obtain a temporary pseudonym TID i , and then generate a short pseudonym identity SID i,m to communicate with other vehicles. Neither the identity authentication nor the temporary pseudonym exchange phase uses real identity information. Therefore, an attacker cannot extract the real identity of the vehicle from the communication.

[0168] In addition, when the vehicle receives a message with the short pseudonym identity SID i,mWhen sending false information, report it to the trusted authority TA. Since the trusted authority TA stores the mapping relationship and secret value between the vehicle identity and the temporary pseudonym, TA can calculate the short pseudonym Obtain the available short pseudonyms of all vehicles, and based on the short pseudonym identity SID i,m Retrieve the corresponding true identity of the vehicle. Therefore, the solution in this paper can achieve the identity traceability of malicious vehicles.

[0169] Therefore, this embodiment can achieve the identity privacy protection of vehicles, Q.E.D.

[0170] Theorem 4 This embodiment can achieve the unlinkability of vehicle pseudonyms.

[0171] Proof In this embodiment, the short pseudonym is generated independently by the vehicle, and its generation formula is: short pseudonym If an attacker wants to successfully infer the correlation between the current short pseudonym SID i,k and the previous short pseudonym SID i,k-1 it needs to solve the ECDLP difficult problem and restore the original data of the H1 hash function according to the hash value. Based on the ECDLP difficult problem and the one-way property of the hash function, the current pseudonym SID i,k and the previous pseudonym SID i,k-1 are not correlated. Therefore, this embodiment provides the unlinkability between pseudonyms, Q.E.D.

[0172] Embodiment 2

[0173] To verify the feasibility of this embodiment, Embodiment 2 compares the feasibility of this embodiment with other pseudonym exchange schemes, including Scheme 1 proposed by scholars such as Li X in "PAPU: Pseudonym swap with provable unlinkability based on differential privacy in VANETs", Scheme 2 proposed by scholars such as Zhang W in "DPSP: A Dynamic Pseudonym Swap Program Based Location Privacy Protection Algorithm for Internet of Vehicles", and Scheme 3 proposed by scholars such as Mdee A in "Security compliant and cooperative pseudonyms swap for location privacy preservation in VANETs" for analysis.

[0174] 1. Performance analysis

[0175] (1) Storage Overhead Analysis and Comparison

[0176] Compare the overhead required for storing kana. For ease of analysis, pre - define the sizes of the parameters involved in storage: the length of the vehicle's private key is 32 bytes, the length of the public key is 33 bytes, the length of the vehicle identity identifier and kana is 33 bytes, the length of the secret value and the transition value is 32 bytes, and the length of the signature is 64 bytes. The kana certificate consists of the vehicle kana, the public key, and the signature of the trusted authority, and its length is 130 bytes.

[0177] Compare the storage overhead of this embodiment with that of Schemes 1 - 3, as shown in Table 4 below.

[0178] Table 4

[0179]

[0180] The main storage overhead of this embodiment includes the information stored by the vehicle itself and the vehicle - kana mapping table stored by the TA. The information stored by the vehicle itself in this embodiment includes the vehicle identity identifier, the vehicle's public and private keys, the secret value k i 、the long kana certificate, the temporary kana and its private key, the transition value, and the generated short kana and its private key, and its storage overhead is 33×4 + 32×5 + 130 = 422 bytes. The TA stores the vehicle identity identifier, the long kana, the secret value, the temporary kana and its private key in the vehicle - kana mapping table, and its storage overhead is 33×3 + 32×2 = 163 bytes.

[0181] In Scheme 1, the trusted authority TA generates a legal kana certificate for the vehicle. The vehicle stores the allocated kana certificate in the OBU and uses this kana certificate to broadcast beacon messages. The vehicle needs to store the vehicle identity identifier, the vehicle's public and private keys, the kana certificate and the corresponding private key, and its storage overhead is 33×2 + 32×2 + 130 = 260 bytes. The trusted authority records the mapping of the vehicle and the kana, and stores the vehicle identity identifier and the kana, and its storage overhead is 33×2 = 66 bytes.

[0182] In Solution 2, the system consists of three parts: the user layer, the fog layer, and the cloud layer. Among them, vehicles in the user layer need to store vehicle identity identifiers, vehicle public and private keys, vehicle certificates, and k pseudonym certificates and corresponding private keys. Its storage overhead is 33×2 + 32 + 130 + k×(32 + 130) = 228 + 162k bytes. The fog layer consists of several adjacent RSUs with similar functions, which generate, store, and distribute a certain number of pseudonym certificates and private keys for vehicles traveling in the vehicle network as needed. The fog layer RSUs need to store vehicle identifiers and the vehicle pseudonym pool, and its storage overhead is 33 + k×33 = 33 + 33k bytes. The cloud layer TA is responsible for managing the nodes in the model and needs to store vehicle identity identifiers and the mapping between identity identifiers and pseudonyms. Its storage overhead is 33 + k×33 = 33 + 33k bytes.

[0183] In Solution 3, the TA provides each legal vehicle with a non-exchangeable pseudonym certificate and k exchangeable pseudonym certificates and corresponding private keys. The vehicle protects its location privacy by exchanging and changing the currently used exchangeable pseudonyms. Among them, the vehicle needs to store vehicle identity identifiers, vehicle public and private keys, long pseudonym certificates and their private keys, and k short pseudonym certificates and corresponding private keys. Its storage overhead is 33×2 + 32×2 + 130 + k×(130 + 32) = 260 + 162k bytes. The TA stores the vehicle identity identifiers, non-exchangeable pseudonyms, and k exchangeable pseudonyms of each vehicle user in the vehicle-pseudonym link table, and calculates its storage overhead as 33×2 + k×33 = 66 + 33k bytes.

[0184] Figure 6 It shows the comparison of the storage overheads of different solutions as the number of pseudonyms required by the vehicle increases. As can be seen from the figure, in this embodiment, during the process of increasing pseudonym requirements, the storage overhead advantage increases significantly. This is because Solutions 2 and 3 use the pseudonym pool technology, and vehicles need to store multiple pseudonyms for subsequent use, resulting in a linear increase in storage overhead. However, this embodiment allows vehicles to autonomously update and generate pseudonyms when needed without prior storage, and the storage overhead does not increase with the increase in demand. The storage overhead performance of Solution 1 is good, but its vehicle only stores a single pseudonym and cannot update it autonomously, and needs to rely on the RSU to complete pseudonym update. Compared with Solutions 2 and 3, this embodiment shows the optimal performance in the storage overhead of vehicles and trusted institutions and has significant advantages. At the same time, compared with Solution 1, this embodiment reduces the dependence on the roadside unit RSU and is more suitable for the vehicle network environment.

[0185] (2) Analysis and comparison of communication overhead

[0186] Compare the communication overhead required during the pseudonym exchange process. For the convenience of analysis, pre-define the sizes of the parameters involved in the communication process: the length of the vehicle private key is 32 bytes, the public key length is 33 bytes, the pseudonym length is 33 bytes, the transition value length is 32 bytes, the signature length is 64 bytes, the encryption length is 33 bytes, and the timestamp length is 8 bytes. The pseudonym certificate consists of the vehicle pseudonym, the public key, and the signature of the trusted authority, and its length is 130 bytes.

[0187] Compare the communication overhead of this embodiment with that of Schemes 1-3, as shown in Table 5 below.

[0188] Table 5

[0189]

[0190]

[0191] During the exchange of the vehicle's temporary pseudonym in this embodiment, multiple interactions are required. Its communication overhead mainly includes: the requesting vehicle sending an encrypted exchange request to the neighboring vehicle, the neighboring vehicle returning an encrypted response, the two vehicles sending a pseudonym exchange confirmation to the TA, and the vehicle independently updating the short pseudonym after each temporary pseudonym exchange. The total communication overhead is 10×33 + 4×8 + 2×32 + 4×64 + 4×130 = 1202 bytes.

[0192] In Scheme 1, after the vehicle enters the communication domain of the RSU, the RSU assists the vehicles within the domain in pseudonym exchange. Its communication overhead includes: the requesting vehicle broadcasting a request to find a collaborator, the requesting vehicle sending a pseudonym exchange request to the RSU, the response returned by the RSU, and the RSU reporting the new vehicle-pseudonym mapping to the TA. The total communication overhead is 9×33 + 4×8 + 4×32 + 4×64 + 2×130 = 973 bytes.

[0193] In Scheme 2, when the vehicle needs to exchange pseudonyms, it requests to establish a pseudonym exchange area and exchanges pseudonyms with one of its neighboring vehicles. Its communication overhead includes: the pseudonym exchange area establishment request sent by the requesting vehicle, the response from the neighboring vehicle, the exchange of pseudonym certificates, and the requesting vehicle sending a pseudonym exchange confirmation to the fog layer. The total communication overhead is 10×33 + 5×8 + 4×32 + 5×64 + 2×130 = 1078 bytes.

[0194] In Scheme 3, when the vehicle exchanges pseudonyms, it needs to interact with the neighboring vehicle multiple times. Its communication overhead includes: the requesting vehicle sending an exchange request, the neighboring vehicle returning a response, the exchange of short pseudonym private keys, the requesting vehicle broadcasting a pseudonym exchange confirmation, and the two vehicles reporting the new vehicle-pseudonym mapping to the TA. The total communication overhead is 14×33 + 5×8 + 2×32 + 7×64 + 2×130 = 1274 bytes.

[0195] Figure 7 It shows the comparison of the communication overhead required for each scheme as the number of kana updates increases. As can be seen from the figure, compared with Schemes 1-3, this embodiment has more communication advantages when it comes to frequent kana updates. This is because in Scheme 1, the vehicle only stores a single kana, and a kana exchange needs to be performed every time it is updated; although kana pools are constructed in Schemes 2 and 3, only one kana can be obtained in a single exchange, and the exchange operation needs to be repeated during multiple updates, resulting in an increase in communication overhead. In contrast, in this embodiment, after the vehicle exchanges the temporary kana, it can independently generate short kana multiple times based on the temporary kana, so that subsequent short kana updates do not require repeated kana exchange operations, thereby reducing the communication overhead.

[0196] The above two embodiments fully verify the feasibility and security of this embodiment. At the same time, through the performance comparison with other existing kana exchange schemes, it fully demonstrates the innovation and performance superiority of this scheme.

[0197] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An efficient pseudonym dynamic update method based on neighbor cooperation algorithm in the vehicle networking environment, characterized in that, It includes the following steps: S1. System initialization; S2. Two-way identity authentication; S3. Generation and update of short kana; S4. Maintenance of neighbor vehicle list; S5. Temporary kana exchange; S6. Update of vehicle-kana mapping; Step S6 includes the following steps: S61, Vehicle V i Generate signature Where TS is the timestamp, It is a trusted institution TA is V i Long Kana PID i Long Kana Certificate issued, TID i 、TID j V i 、V j A temporary pseudonym, Indicated by V i Private Key Sign the message and then construct the encrypted message Sent to a trusted institution TA, where Indicates the use of a trusted institution public key PK TA Encrypt the message; S62, V j Generate Then construct an encrypted message Send it to TA; The trusted authority private key SK for S63 and TA TA Decrypt V i And V j The sent message, and complete the validity verification according to TS, then complete the message integrity check according to σ6 and σ7 respectively. If the verifications all pass, TA further compares the TIDs in the two messages i 、TID j Whether they are the same. If they are consistent, TA retrieves according to PID i 、PID j In the vehicle-pseudonym mapping table to locate the corresponding temporary pseudonym and its private key And swap the two records; S64, if TA judges V i and V j If the temporary pseudonym sent is inconsistent, the abnormal behavior needs to be traced back and TA will revoke the abnormal vehicle V i Certificate of long kana At the same time, V i Then, TA notifies the victim vehicle V j Re-authenticate to obtain a new temporary pseudonym.

2. The efficient pseudonym dynamic update method based on the neighbor cooperation algorithm according to claim 1, characterized in that Step S1 includes the following steps: S11. Input the system security parameter λ. TA generates a large prime number q and selects parameters a and b in the prime field F q to generate the elliptic curve E: y 2 = x 3 + ax + b (mod q). The parameters need to satisfy: Δ = 4a 2 + 27b 2 ≠ 0 (mod q). Select an additive cyclic group G on the elliptic curve, whose order is q and the generator is P; S12. TA selects a random number s as the private key SK of the trusted authority in the multiplicative cyclic group of integers of order q - 1 and calculates the public key PK of the trusted authority according to the double - point operation of the elliptic curve TA PK = s×P; TA ​ S13. Select two secure hash functions: H2:{0,1} * →G; S14. The TA public system parameters params = {G, q, P, H1, H2, PK TA}; S15. Registration of roadside unit RSU. TA completes the registration for RSU and assigns an identity identifier to RSU, generates public key, private key and issues a certificate; S16. Vehicle registration. TA completes the registration for the vehicle and assigns an identity identifier to the vehicle, generates public key, private key, secret value, long kana and issues a long kana certificate.

3. The efficient pseudonym dynamic update method based on the neighbor cooperation algorithm according to claim 2, wherein In step S15, the process of RSU registration includes the following steps: S151. TA selects a random number As the roadside unit R j Private key Calculate R j Public key S152, TA is R j Allocate a unique identity And issue a certificate The certificate contains The signature information of TA; S153. TA sends to R j .

4. The efficient pseudonym dynamic update method based on the neighbor cooperation algorithm according to claim 2, characterized in that In step S16, the process of vehicle registration includes the following steps: S161. TA selects a random number as the private key of V i Calculate the public key V i ​​ S162, TA is V i Allocate a unique identity identifier Secret value k i , long vacation name PID i , and issue a long vacation name certificate The certificate contains PID i , Signature information of TA; S163. TA establishes a vehicle-pseudonym mapping table, and stores the i of the PID i , k i field information into the mapping table. The TID i and field information values are initially empty, and a mapping between the vehicle and the temporary pseudonym is established; S164. TA sends k i , PID i , to V i , and V i stores the information in the on-vehicle unit OBU.

5. The efficient pseudonym dynamic update method based on the neighbor cooperation algorithm according to claim 1, wherein Step S2 includes the following steps: S21, R j Periodically broadcast messages within its broadcast domain S22, V i Receive the message, check the validity of the TS, and then obtain from and verify σ1; ​ S23, V i Use Generate Construct an identity authentication request message And send it to R j ; S24, R j After receiving the message, use to decrypt the message. After decryption, check the validity of the TS, and then obtain from and verify σ2; S25, R j Select a random number as the temporary pseudonym private key of V i Calculate the temporary pseudonym TID of V i i = p i × P;​​ S26, R j Use Generate Construct an encrypted message And send it to V i ; S27, R j Construct an encrypted message and send it to TA; S28. After receiving the message, TA uses SK TA to decrypt it and verify the timeliness of the message according to TS. If the verification passes, TA further verifies σ3 to ensure the legality of the message. After the verification passes, TID i is updated and stored in the PID i line in the vehicle-pseudonym mapping table.

6. The efficient pseudonym dynamic update method based on the neighbor cooperation algorithm according to claim 1, characterized in that Step S3 includes the following steps: S31, V i After receiving R j the sent message use to decrypt, and perform validity verification according to TS. After passing the verification, further verify σ3, and store TID i into the OBU; S32, V i Calculate the transition value Calculate and generate the first kana private key SK i,1 = H1(M i,1 ) and the first kana SID i,1 = SK i,1 × P; S33. After using the short kana for a period of time, the vehicle autonomously updates the short kana and calculates M i,k = H2(M i,k-1 ), calculates and generates the k-th short kana private key SK i,k = H1(M i,k ), and the corresponding short kana SID i,k = SK i,k × P.

7. The efficient pseudonym dynamic update method based on the neighbor cooperation algorithm according to claim 1, wherein Step S4 includes the following steps: S41, V i Periodically broadcast the basic safety message BSM, where BSM is one of the core message types for vehicle-to-vehicle communication; the BSM contains the status and identity information of the vehicle, namely location, speed, driving direction, timestamp, and pseudonym information; the optional fields of the BSM allow customizing data based on the standard BSM; S42, V i Based on the received BSM of neighboring vehicle V j maintain the neighboring vehicle list N i,t .

8. The efficient pseudonym dynamic update method based on the neighbor cooperation algorithm according to claim 7, characterized in that In the step S41, V i The process of periodically broadcasting BSM includes the following steps: S411, V i Expand the optional fields of the BSM, define the pseudonym exchange flag RTS and the synchronized pseudonym update flag PSR. Among them, the RTS flag is used to indicate whether the vehicle's current state allows pseudonym exchange. If its value is 1, it means yes; if its value is 0, it means the vehicle is in the process of updating or exchanging pseudonyms. The PSR flag is default set to 0. If its value is 1, it means that the requesting vehicle has completed the temporary pseudonym exchange and the neighboring vehicles need to synchronously update the short pseudonyms. S412, V i Periodically broadcast BSM. At time t, V i The broadcast BSM contains SID i,m , position POS i,t , speed VEL i,t , driving direction H i,t , timestamps TS, RTS i,t and PSR i,t .

9. The efficient pseudonym dynamic update method based on the neighbor cooperation algorithm according to claim 7, wherein In the step S42, V i maintains N i,t The process includes the following steps: S421, V i Upon receiving the BSM of V j , first check whether the RTS in the message j,t is 1, and whether H i,t is consistent with H j,t to determine whether it currently supports pseudonym exchange. If not, V i further determines V j 's short pseudonym SID j,n is within N i,t . If so, the short pseudonym needs to be deleted and proceed to step S422; S422, V i Calculate the distance d between S422 and V j using the formula d i,j,t = |POS j,t - POS i,t |. Compare this distance d with the neighbor distance standard d0. If d i,j,t is greater than d0, then further determine whether SID j,n is within N i,t . If it exists, delete it; otherwise, calculate the position deviation between the two vehicles The calculation method is where the square predicted distance SQD i,j,t+T is calculated as SQD i,j,t+T = ((POS j,t - POS i,t ) + (VEL j,t - VEL i,t ) × T) 2 ; S423, V i Compare with the position standard deviation sd0. If is greater than sd0, then determine whether SID j,n is within N i,t . If it is, delete the hiragana; otherwise, add the hiragana within N i,t .

10. The efficient pseudonym dynamic update method based on the neighbor cooperation algorithm according to claim 1, characterized in that Step S5 includes the following steps: S51, V i Generate Then construct an encrypted request message Send it to V j ; S52, V j Use SK j,n Decrypt this request message, perform time validity verification according to TS, and then perform message integrity verification according to σ4. If the verification passes, V j will store TID i and into its own OBU; S53, V j Generate Then construct an encrypted response message Send it to V i ; S54, V i Use to decrypt this response message, verify the time validity according to the TS completion time, and then complete the message integrity check according to σ5. If the verification passes, V i will store the TID j and into its own OBU, and calculate to generate SK i,1 = H1(M i,1 ) and SID i,1 = SK i,1 × P, and record the pseudonym generation time as T0. If the current time T1 minus T0 is T (where T is the current pseudonym survival period), V i needs to immediately update the short pseudonym; S55, V i Set the PSR in the BSM i,t to 1 and broadcast it to remind all neighboring vehicles to synchronize the pseudonym update; S56. The neighboring vehicle receives the BSM of V i , first performs validity verification according to the TS, and further checks whether the PSR i,t is 1. If the PSR i,t is 1, vehicle V j calculates to generate SK j,1 = H1(M j,1 ) and SID j,1 = SK j,1 × P. At the same time, the remaining neighboring vehicles (taking the neighboring vehicle V l,k with the short pseudonym SID l as an example) calculate M l,k+1 = H2(M l,k ), generate SK l,k+1 = H1(M l,k+1 ) and SID l,k+1 = SK l,k+1 × P. The neighboring vehicles participating in the short pseudonym update respectively record T0. If T1 minus T0 is T, all neighboring vehicles need to immediately update the short pseudonym.

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