A vehicle authentication method with privacy protection based on PUF

Abstract

The present invention proposes a vehicle authentication method with privacy protection based on PUF, and the steps are as follows: system initialization: selecting an on-board unit OBU and an elliptic curve with a PUF function; communicating with a trust agency TA, the on-board unit OBU registers, and the roadside unit RSU registers; the vehicle user logs in to the on-board unit OBU; authentication between the on-board unit OBU of the vehicle and the roadside unit RSU: verifying the legitimacy of the on-board unit OBU through the authentication parameters of the on-board unit OBU, the PUF function and the PUF verification value and calculating the communication key I; authentication of the on-board unit OBU between vehicles: generating a temporary private key and a public key using a random number generation function and a base point, verifying the legitimacy of the vehicle through a secure hash function and authentication parameters and generating a communication key. The authentication of vehicles and vehicles and the authentication of vehicles and roadside RSUs of the present invention do not require the participation of the trust agency TA, and the reliability of authentication is guaranteed by using the PUF function and the elliptic curve.

Description

Technical Field

[0001] The present invention relates to the technical field of mobile communications and edge computing, and in particular to a vehicle authentication method with privacy protection based on PUF, which utilizes the output uniqueness of a physical unclonable function (PUF) to construct a vehicle identity authentication method, and performs vehicle authentication based on PUF and elliptic curve encryption. Background Art

[0002] In recent years, as more and more vehicles are equipped with wireless communication technology and on-board sensors, and because these devices play a key role in the field of intelligent transportation, vehicular ad hoc networks (VANET) are becoming more and more common. A typical VANET mainly includes a trusted authority (TA), a road side unit (RSU), and a vehicle equipped with an on-board unit (OBU) with sensing and communication capabilities. The main role of the trusted authority TA is to be responsible for the initialization of the entire system, complete the registration of all vehicles and road side units RSU, and maintain all resources required to maintain the normal operation of the system, including communication links, road side units RSU, and vehicle related information. Each vehicle has an on-board unit OBU, including various sensors, user interfaces, storage and communication devices. Through these sensors and communication devices, the vehicle can not only understand its own position, direction, speed, acceleration and other vehicle information in real time, but also perceive the information of the external environment through various environmental sensors, including temperature, humidity, light intensity, etc., which not only facilitates the driver to understand the vehicle information in time, but also can respond to external changes in time. Roadside units (RSUs) are usually installed at fixed locations on the roadside and serve as a bridge for communication between vehicles and trusted authorities (TAs). They are responsible for forwarding messages collected by vehicles to trusted authorization centers (TAs) or forwarding some public messages from servers to vehicles.

[0003] The structure of VANET determines that the messages between vehicles (V2V) and between vehicles and roadside units (RSU) can only be transmitted and shared wirelessly. In the current VANET practice, whether it is V2V or V2R, the communication methods currently used mainly include two major technical schools: C-V2X (vehicle-to-vehicle communication based on cellular technology) and DSRC (dedicated short-range communication technology). However, due to the open nature of wireless networks, no matter which technical school is used, all kinds of messages transmitted in VANET are likely to be eavesdropped or tampered with. In addition, attackers can attack the communication channel of VANET by using eavesdropping, tampering and other attack methods to obtain relevant information or obtain illegal benefits. In addition, the private and sensitive data of vehicles (such as driving routes or identity information) may also be leaked. Therefore, the secure transmission and privacy protection of messages between vehicles are the primary concerns in VANET. In view of the above problems, in order to ensure the transmission security and privacy protection of messages, a robust, secure and efficient identity authentication and privacy protection scheme is needed to protect VANET. The identity authentication protocol can prove the legitimacy of the vehicle node and the integrity of the message, while the privacy protection can maintain the protection and privacy of sensitive information.

[0004] The invention patent with application number 202210212900.7 discloses a PUF-based lightweight privacy protection batch authentication method for Internet of Vehicles. In the initialization setting stage, the trusted center TA selects its own private key, a secure one-way hash function, and a symmetric key algorithm; in the registration stage, the trusted center TA calculates and stores secret information for vehicles and roadside units RSU for subsequent identity authentication; in the batch authentication stage, the trusted center TA, roadside units RSU, and vehicles use instantly generated random numbers and previously stored secret information to batch authenticate the legitimate identities of the interacting parties. If the authentication is successful, the legitimate vehicle will establish a session key with other vehicles and RSUs in the area for subsequent secure communication; the physical unclonable function PUF is used to avoid the digital signature operation in the information exchange V2X authentication, simplify the steps, and participants only need to perform hash and XOR operations to meet the operations required for the authentication process. This method not only meets various security properties, but also realizes the pseudo-identity traceability of the vehicle, meeting the conditional anonymity requirements. However, the roadside unit RSU can only verify the legitimacy of the vehicle with the participation of the trusted center TA. Although this centralized authentication method that requires the participation of TA in the authentication process can meet the requirements of anonymity and authentication, it also has some defects: First, the centralized authentication method will cause the emergence of computing bottlenecks. As the number of vehicles gradually increases, all vehicles that need to be authenticated require the participation of the trusted center TA in the authentication process, which is a great challenge for the limited computing and communication resources of the trusted center TA. In addition, if the TA's work is unstable due to other factors, it will directly lead to the inability to complete the vehicle's authentication process. In addition, in the centralized authentication method that requires the participation of the trusted center TA, during the authentication process, the authentication-related messages will be transmitted between the vehicle, the roadside unit and the trusted center TA, which increases the communication consumption of the authentication process, thereby prolonging the time required for the authentication process. Summary of the invention

[0005] In view of the technical problems that the existing vehicle authentication methods all require the participation of a trusted authorization center TA and cannot guarantee the transmission security and privacy protection of messages, the present invention proposes a vehicle authentication method with privacy protection based on PUF. The verification between vehicles and the verification between vehicles and roadside RSU do not require the participation of a trusted institution TA, and the uniqueness of the PUF function response and the discreteness of the elliptic curve encryption function are utilized to ensure the reliability of vehicle authentication and the mutual authentication between authentication entities.

[0006] In order to achieve the above object, the technical solution of the present invention is implemented as follows: a vehicle authentication method with privacy protection based on PUF, the steps of which are as follows:

[0007] Step 1: System initialization: Select an on-board unit OBU with PUF function and an elliptic curve. The trust agency TA selects a base point and two secure hash functions on the elliptic curve, and uses the base point to generate its own private key and public key. The trust agency TA uses a random number generation algorithm to generate two random numbers as secret values ​​and save them.

[0008] Step 2, registration of the on-board unit OBU: the on-board unit OBU generates the PUF verification value and the intermediate variable through the identity identifier, vehicle key, PUF function, base point P, two secret values ​​and a secure hash function to communicate with the trust agency TA, the trust agency TA generates the authentication parameters of the vehicle, transmits them to the on-board unit OBU through a secure communication channel and saves them in the vehicle list VTL; registration of the roadside unit RSU: the trust agency TA generates the private key and public key of the roadside unit RSU through the random number generation algorithm and the base point P, and transmits the private key and public key of the roadside unit RSU to the roadside unit RSU;

[0009] Step 3: The vehicle user logs in to the on-board unit OBU: The vehicle user logs in to the on-board unit OBU through the identity identifier and the vehicle key. After the on-board unit OBU determines the correctness of the PUF verification value through the PUF function, the vehicle user is allowed to log in to the on-board unit OBU;

[0010] Step 4: Authentication between the vehicle's onboard unit OBU and the roadside unit RSU: Roadside unit RSU j Verify the legitimacy of the on-board unit OBU by verifying the authentication parameters, PUF function and PUF verification value of the on-board unit OBU, and calculate the communication key I using the secret value, the identity identifier of the on-board unit OBU and the vehicle key;

[0011] Step 5. Authentication of the on-board unit (OBU) between vehicles: The on-board unit of one vehicle generates a temporary private key and public key using a random number generation function and a base point P, and sends the public key to the on-board unit of another vehicle. The on-board unit of the other vehicle verifies the freshness of the message through a timestamp, verifies the legitimacy of a vehicle through a secure hash function and authentication parameters, and generates a communication key II.

[0012] Preferably, the elliptic curve is an elliptic curve E selected over a finite field GF(p) consisting of a large prime number p. p (a,b):y1 2 =x1 3 +ax1+b and satisfies 4a 3 +27b 2 ≠0(mod p), where a, b∈Z q *is the constant of the elliptic curve, x1 and y1 are the independent variable and dependent variable of the elliptic curve; the base point P is the trust institution TA on the elliptic curve E p A point of order q is selected on (a, b); the two secure hash functions are respectively the secure hash function h(·) and the secure hash function H(·), and the secure hash function From 0,1 string to finite field of order q Hash function; secure hash function H:E p (a,b)→{0,1} l For the elliptic curve E p The trust agency TA generates two random numbers using a random number generation algorithm. The method for the trust institution TA to generate its own private key and public key is as follows: the trust institution TA generates a random number using a random number generation algorithm As its own private key, use the base point P and the private key s to calculate the corresponding public key TPK = s·P; the trust institution TA uses the public parameters {E p (a,b),q,P,h(·),H(·),TPK} are made public.

[0013] Preferably, the method for registering the on-board unit OBU is:

[0014] Step VR1: Vehicle V i The on-board unit OBU selects a unique ID i And the corresponding key PW i ; Vehicle V i Generate random numbers using random number generation algorithms And calculate the hash value And PUF verification value Q i =PUF(ID i ||h(PW i ⊕b)); Vehicle V i The on-board unit OBU generates a message {ID i ,h(PW i ⊕b)} and transmit the message to the trusted authority TA through a secure communication channel; where PUF(·) is the physical unclonable function owned by the on-board unit OBU, || is the concatenation operator of two strings, and ⊕ is the XOR operation;

[0015] Step VR2: Upon receiving the message {ID i ,h(PW i ⊕b)}, the trusted authority TA calculates the intermediate variable D i=h(x⊕ID i ⊕h(PW i ⊕b)) and convert the message {D i} is transmitted to the vehicle V through a secure communication channel i On-board unit OBU; vehicle V i The on-board unit OBU calculates the value R based on the received message i =PUF(D i ) and set the value R i Send back to the trusted institution TA;

[0016] Step VR3: Upon receiving the value R i Afterwards, the trust authority TA calculates the authentication parameters:

[0017] C i =(h(ID i ⊕h(PW i ⊕b))+y)·P,

[0018] Cert i =h(R i )·x·P

[0019] Among them, C i , Cert i Represents vehicle V i Authentication parameters of the on-board unit OBU;

[0020] Then, the trusted authority TA generates a message {C i ,Cert i} and pass the message to the vehicle V through a secure communication channel i The on-board unit OBU; the trust authority TA builds a record <ID i ,Cert i ,C i >, and store the record in the vehicle list VTL of the backend database server;

[0021] Step VR4: Vehicle V i The on-board unit OBU receives the message {C i ,Cert i}, the vehicle V i The on-board unit OBU will have the parameters <b,Q i ,C i ,Cert i >Stored in its tamper-proof device TPD.

[0022] Preferably, the registration method of the roadside unit RSU is:

[0023] Step RR1: The trusted institution TA generates a random number using a random number generation algorithm And use it as a roadside unit RSU j The private key of the roadside unit is used to calculate the RSU j Public key: PK R =s R ·P;

[0024] Step RR2: Then, the trusted authority TA calculates the intermediate variable F j =s R ·x·P and set the parameter <F j ,s R ,x,PK R >Store in roadside unit RSU j The tamper-proof device TPD; the trust agency TA will roadside unit RSU j Parameters of <F j ,s R ,x,PK R >Roadside equipment table stored in the backend database server.

[0025] Preferably, the method for the vehicle user to log in to the on-board unit OBU is:

[0026] Step L-1: User U enters the user's ID on the interface of the on-board unit OBU i And the vehicle key PW i ;

[0027] Step L-2: Vehicle V i The on-board unit OBU uses the stored random number b to calculate the hash value h(PW i ⊕b), and use its own PUF function to calculate the intermediate variable Q i '=PUF(ID i ||h(PW i ⊕ b));

[0028] The on-board unit OBU converts the intermediate variable Q i 'Compare with the PUF verification value Q stored by itself i If they are equal, user U is allowed to perform subsequent authentication operations; otherwise, vehicle V i The OBU prompts the user to enter the ID i And the vehicle key PW i Error, prompt the user to re-enter.

[0029] Preferably, when the vehicle V i Drive to the roadside unit RSU j After the coverage area, the vehicle V i On-board unit OBU and roadside unit RSU j The authentication method between them is:

[0030] Step A-RV1: Vehicle V i The on-board unit OBU uses a random number generation function to generate a random number r vi ∈Z q * , and use the instant to generate a timestamp T i Calculate intermediate variables:

[0031] RPK vi =r vi ·P,

[0032] E i =H(r vi ·PK R ),

[0033]

[0034] Token i =H(r vi ·TPK)⊕(Cert i ||T i );

[0035] Among them, E i For vehicle V i Temporary communication key with the roadside unit RSU; RPK vi is the temporary key E i A component used by roadside units to construct temporary communication keys; F i Token i Together as a vehicle V i Authentication credentials used to verify vehicle V i Legality of vehicle V i The on-board unit OBU generates a message {F i ,Token i ,RPK vi ,T i} and transmit the message to the roadside unit RSU via wireless j ;

[0036] Step A-RV2: Receive message {F i ,Token i ,RPK vi ,T i}After that, the roadside unit RSU j Determine timestamp T i If the timestamp T i Meet the freshness condition, roadside unit RSU j Calculate intermediate variables: E i '=H(sR ·RPK vi )and And extract the value from it Authentication Parameter C i and timestamp T i ;

[0037] Roadside Unit RSU j Calculate authentication parameters And judge equation C i '=C i Is it true? If the equation is true, the roadside unit RSU j Consider vehicle V i For legal cars, and calculate the intermediate variables:

[0038] H i =ID i ⊕h(PW i ⊕b)⊕x⊕T j ,

[0039]

[0040] Among them, T j Roadside Unit RSU j The new timestamp of

[0041] Roadside Unit RSU j The message {L i ,T j}Send to vehicle V i The on-board unit OBU and calculate SK ji =h(H i ⊕T i ) as its relationship with the vehicle V i The key for subsequent communication with the on-board unit OBU;

[0042] Step A-RV3: Receive message {L i ,T j}, the vehicle V i The on-board unit OBU determines the timestamp T j If the timestamp T j If the freshness condition is met, then the vehicle V i The on-board unit OBU calculates the intermediate variable L i ⊕E i And extract the ID from it i ⊕h(PW i ⊕b)⊕x, and then calculate the intermediate variable:

[0043] D i '=h(ID i ⊕h(PWi ⊕b)⊕x),

[0044] R i '=PUF(D i ');

[0045] Vehicle V i The on-board unit OBU judgment equation R i '=R i Is it true? If the equation is true, then the vehicle V i The on-board unit OBU is considered as the roadside unit RSU j is a legitimate roadside unit and calculates the communication key SK used by both parties for communication ij =h(ID i ⊕h(PW i ⊕b)⊕x⊕T i ⊕T i ).

[0046] Preferably, the method of authenticating the on-board unit OBU between vehicles in step 5 is:

[0047] Step A-VV1: Vehicle V m The on-board unit OBU uses a random number generation function to generate a random number r vm ∈Z q * As its temporary key, using the random number r vm Calculate the corresponding public key RPK vm =r vm ·P; Vehicle V m The on-board unit OBU constructs the message {hello,RPK vm ,T1} and send the message to vehicle V wirelessly n ; Among them, hello represents a greeting packet, which is used for the first call to establish a connection;

[0048] Step A-VV2: Upon receiving the message {hello,RPK vm ,T1}, vehicle V n The vehicle-mounted unit OBU checks the freshness of the timestamp T1. If the timestamp T1 meets the freshness requirement, the vehicle V n The on-board unit OBU uses a random number generation function to generate a random number r vn ∈Z q * And calculate the intermediate variables:

[0049] RPK vn =r vn ·P,

[0050] M1=H(rvn ·RPK vm )⊕(h(ID n )||Cert n ||T2),

[0051] Token vn =H(r vn ·TPK)⊕(Cert n ||T2),

[0052] Wherein, T2 is the timestamp formed by the instant when the above intermediate variable is calculated;

[0053] Then, the vehicle V n The on-board unit OBU constructs the message {M1,Token vn ,RPK vn ,T2} and send the message to the vehicle V wirelessly m ;

[0054] Step A-VV3: Upon receiving the message {M1,Token vn ,RPK vn ,T2}, vehicle V m The on-board unit OBU calculates the hash value H(r vm ·RPK vn )⊕M1 to extract the parameter h(ID n ), authentication parameters Cert n , timestamp T2; determine the freshness of timestamp T2. If timestamp T2 meets the freshness requirement, verify equation h(ID n )·Cert m =h(ID m )·Cert n Is it true? If the equation is true, the vehicle V m The on-board unit OBU thinks that the vehicle V n For legal vehicles, and calculate the intermediate variables:

[0055] M2=H(r vm ·RPK vn )⊕(h(ID m )||Cert m ||T3),

[0056] Token vm =H(r vm ·TPK)⊕(Cert m ||T3),

[0057] SK mn =H(h(T3)·h(ID m)·Cert n );

[0058] Vehicle V m The on-board unit OBU generates a message {M2,Token vm ,T3} and send the message to the vehicle V by wireless n ; At the same time, SK mn As a vehicle V m The vehicle-mounted unit OBU and vehicle V n The communication key between the on-board units OBU;

[0059] Step A-VV4: Upon receiving the message {M2,Token vm ,T3}, vehicle V n The on-board unit OBU calculates the hash value H(r vn ·RPK vm )⊕M2 and extract h(ID m ), authentication parameters Cert m , timestamp T3; vehicle V n The on-board unit OBU determines the freshness of the timestamp T3. If the timestamp T3 meets the freshness requirement, it verifies h(ID m )·Cert n =h(ID n )·Cert m Is it true? If the equation is true, then the vehicle V n The on-board unit OBU thinks that the vehicle V m For legal cars; vehicles V n The on-board unit OBU calculates SK nm =H(h(T3)·h(ID n )·Cert m ) and SK nm As its V m The communication key between them.

[0060] Preferably, the random number generation algorithm is a Mersenne Twister algorithm; the identity identifier ID i Using Vehicle V i At least one of the engine number, frame number or production time is generated by a secure hash function; the method for determining the freshness of the timestamp is: determining T c -T≤ΔT, where T c Indicates the time when the message is received, △T refers to the maximum time interval that the system can allow, and T represents the instant when the message is sent and is the timestamp T i , timestamp T j , timestamp T1, timestamp T2 or timestamp T3.

[0061] Preferably, the method further includes tracking of the real identity of the vehicle: the trust authority TA verifies the identity of the vehicle's on-board unit OBU by extracting the authentication parameter and timestamp from the identity parameter in the vehicle's on-board unit OBU.

[0062] Preferably, the tracking method is: the trust institution TA obtains the message {F i ,Token i ,RPK vi ,T i}, use your own private key s to calculate the hash value H(s·RPK vi )⊕Token i And extract the parameter Cert from it i ' and T i ', compare T i 'With timestamp T i Are they consistent? If they are consistent, directly use the timestamp T i ' or parameter Cert i 'Query the vehicle list VTL of the backend database server to obtain the corresponding vehicle ID i .

[0063] Compared with the existing calculation, the present invention has the following beneficial effects: the present invention utilizes the uniqueness of the PUF function response and the discreteness of the elliptic curve encryption function to ensure the reliability of vehicle authentication and mutual authentication between authentication entities. In the registration phase of the present invention, the PUF function in the vehicle OBU is used to generate a unique PUF verification value R i , which is used to authenticate the vehicle user's identifier and password; due to the uniqueness of the PUF function response, an incorrect identifier and password combination cannot generate a unique PUF verification value R i , this method can ensure the legitimacy of the identity of the vehicle user. In addition, in the authentication process of the vehicle and the roadside unit of the present invention, the unclonable property of the physical PUF function is utilized, and only the PUF function of a specific vehicle can be used for a given value D i , in order to calculate the unique PUF response value R i In the authentication process of two different types of entities, the present invention utilizes the discreteness of elliptic curve encryption functions, so that the receiver of the message can easily calculate the corresponding temporary key and decrypt the message when receiving the encrypted information sent by the sender (see the vehicle and roadside unit authentication and vehicle and vehicle authentication process for details), which can ensure that the message transmitted in the authentication process is not obtained by a third party, and then other attacks or illegal activities are carried out. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0065] Figure 1 This is a model diagram of the vehicle network system used in the present invention.

[0066] Figure 2 It is a flow chart of the present invention.

[0067] Figure 3 It is a schematic diagram of the process of vehicle registration in the present invention.

[0068] Figure 4 This is a flow chart of mutual authentication between a vehicle and a roadside unit RSU in the present invention.

[0069] Figure 5 The figure is a flow chart of mutual authentication between vehicles in the present invention. DETAILED DESCRIPTION

[0070] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0071] A vehicle authentication method with privacy protection based on PUF, the system model used in the present invention is as follows Figure 1 As shown, it mainly includes three parts: a trust agency TA, an onboard unit OBU and a roadside unit RSU. All roadside units RSU are connected to the trust agency TA through the Internet. The authentication method of the present invention mainly includes system initialization, registration of vehicles and roadside units RSU, authentication between vehicles and roadside units (V2I authentication) and authentication between vehicles (V2V authentication), identity tracking and other parts. Among them, V2I authentication and V2V authentication are the core of the vehicle authentication method of the present invention. Figure 2 As shown, the specific implementation method of the present invention has the following steps:

[0072] Step 1: System initialization: Select an on-board unit OBU with PUF function and an elliptic curve. The trust agency TA selects a base point P and two secure hash functions on the elliptic curve, and uses the base point P to generate its own private key s and public key TPK. The trust agency TA uses a random number generation algorithm to generate two random numbers as secret values ​​and save them.

[0073] This stage mainly completes the selection of various encryption algorithms required for vehicle authentication and message authentication based on VANET, the setting of initial values, etc. As mentioned above, the trust agency TA is regarded as the trusted management center of VANET, and the entire initialization work is implemented by the trust agency TA.

[0074] Step I1: The manager needs to select an on-board unit (OBU) that has the function of implementing the physical unclonable function (PUF). The implemented PUF should have security features such as the ability to generate unique output (response), reproducibility, and physical unclonability, so as to prepare for the subsequent implementation of the vehicle authentication method. PUF is a function that uses random subtle differences in the manufacturing process of physical structures (such as integrated chips) to generate unique output (response) for a given input (stimulus). This uniqueness can be understood as the "fingerprint" of the device. PUF has the characteristics of unpredictable results, unclonable, and fast operation speed. These characteristics make PUF extremely popular in the fields of key generation and identity authentication.

[0075] Step I2: Select a large prime number p (must reach the commercial security level, for specific requirements, see the National Secret SM2 Algorithm), and select an elliptic curve E built on the finite field GF(p) composed of this prime number. p (a,b):y 2 =x 3 +ax+b and satisfies 4a 3 +27b 2 ≠0(mod p). Then, the trust authority TA selects a base point P of order q on the elliptic curve E. The elliptic curve should have sufficient security to ensure that it cannot be cracked by brute force by the adversary. ECC has excellent characteristics such as short encryption key and fast operation speed, which makes it widely used in many public key encryption algorithms. More and more researchers are also applying it to identity authentication in VANET.

[0076] Step I3: The trust authority TA selects two secure hash functions h(·) and H(·). From 0,1 string to finite field of order q Hash function; H:E p (a,b)→{0,1} l For the elliptic curve E pThe hash function from a point on (a,b) to a 0,1 string of length l. The selected secure hash function must have security features such as anti-preimage, anti-second preimage, and anti-collision.

[0077] Step I4: The trusted institution TA generates a random number using a random number generation algorithm And use it as your own private key. At the same time, use the private key to calculate the corresponding public key TPK = s P. Then, the trust agency TA once again uses the random number generation algorithm to generate two random numbers As a secret value and keep it properly to prevent leakage. The random number generation algorithm used in this method selects the currently popular Mersenne twister algorithm. The algorithm was developed by Makoto Matsumoto and Takushi Nishimura in 1997. It is mainly based on matrix linear recursion on a finite binary field and can make up for many defects of the classical random number generation algorithm.

[0078] Step I5: The trusted authority TA sends the public parameters used by the system {E p (a,b),q,P,h(·),H(·),TPK} are made public, and any participant in the system (including all OBUs and RSUs) can obtain the above parameters through public channels. And keep their private key s and two secret values ​​x and y properly.

[0079] Step 2: Registration of the on-board unit OBU: The on-board unit OBU communicates with the trust authority TA through the identity identifier, vehicle key, PUF function, base point P, two secret values, and a secure hash function to generate the PUF verification value and intermediate variables. The trust authority TA generates the vehicle's authentication parameters, which are passed to the on-board unit OBU through a secure communication channel and saved in the vehicle list VTL.

[0080] Registration of roadside unit RSU: The trust agency TA generates the private key and public key of the roadside unit RSU through a random number generation algorithm and a base point P, and transmits the private key and public key of the roadside unit RSU to the roadside unit RSU.

[0081] All roadside units (RSU) and vehicle onboard units (OBU) must be registered with the trusted authority (TA) before joining the vehicle authentication system. This section includes the registration of onboard units (OBU) and roadside units (RSU). Their registration processes are described as follows:

[0082] Registration of On-Board Unit (OBU): In order to complete the subsequent certification work, each vehicle that needs to use VANET services must register i All vehicles need to be registered with a trusted agency TA. The entire vehicle registration process is as follows Figure 3 As shown, the specific steps are as follows:

[0083] Step VR1: Vehicle V i Choose a unique ID i And the corresponding key PW i To meet the uniqueness requirement, the vehicle V i Identifier ID i The vehicle engine number, frame number, production time and other information can be used to generate a secure hash function. i Generate random numbers using random number generation algorithms And calculate the hash value And PUF verification value Q i =PUF(ID i ||h(PW i ⊕b)). Where PUF(·) is the physical unclonable function of the vehicle's onboard unit OBU. || is a concatenation operator used to concatenate two strings into one string. ⊕ is an exclusive-or operation.

[0084] Then, the vehicle V i The on-board unit OBU generates a message {ID i ,h(PW i ⊕b)} and pass the message to the trusted authority TA through a secure communication channel.

[0085] Step VR2: Upon receiving the message {ID i ,h(PW i ⊕b)}, the trusted authority TA calculates the intermediate variable D i =h(x⊕ID i ⊕h(PW i ⊕b)) and convert the message {D i} is transmitted to the vehicle V through a secure communication channel i The vehicle V i The on-board unit OBU calculates R based on the received message i =PUF(D i ) and set the value R i The value is sent back to the trusted authority TA. This value will be used to verify the vehicle identity later.

[0086] Step VR3: Upon receiving the value R i After that, the trust agency TA calculates:

[0087] C i =(h(ID i ⊕h(PW i ⊕b))+y)·P,

[0088] Cert i =h(Ri )·x·P

[0089] Among them, C i , Cert i Represents vehicle V i Authentication parameters of the on-board unit OBU.

[0090] Then, the trusted authority TA generates a message {C i ,Cert i} and pass the message to the vehicle V through a secure communication channel i The on-board unit OBU. Then, the trust agency TA constructs the above parameters into a record <ID i ,Cert i ,C i >, and store the record in the vehicle list VTL of the background database server for subsequent search of the vehicle's true identity. The vehicle list VTL stores relevant information about the vehicle, and the trust agency TA is used to manage the vehicle's database.

[0091] Step VR4: Vehicle V i The on-board unit OBU receives the message {C i ,Cert i}, the vehicle V i The on-board unit OBU will have the parameters <b,Q i ,C i ,Cert i >Stored in its tamper-proof device TPD.

[0092] RSU registration: Each roadside unit RSU needs to register with the trust authority TA before being deployed on the roadside to participate in the work of VANET. Without loss of generality, assume that one of the roadside units RSU is RSU j , the registration process is detailed as follows:

[0093] Step RR1: The trusted institution TA generates a random number using a random number generation algorithm and use it as RSU j The private key is then calculated to get the corresponding public key: PK R =s R ·P.

[0094] Step RR2: Then, the trusted authority TA calculates the intermediate variable F j =s R ·x·P and set the parameter <F j ,s R ,x,PK R >Delivered to the roadside unit RSU via a secure communication channel j , then the roadside unit RSUj These parameters are stored in its own tamper-proof device TPD. Then, the trust agency TA stores the relevant information of the roadside unit in the roadside device table of the background database server to prevent the roadside unit from being captured by the adversary and causing adverse effects. j It is used for the subsequent confidential communication between the roadside unit and the TA, and the x value is used for mutual verification between the roadside unit and the vehicle during the subsequent authentication process.

[0095] Step 3: The vehicle user logs in to the on-board unit OBU: The vehicle user logs in to the on-board unit OBU through the identity identifier and the vehicle key. After the on-board unit OBU determines the correctness of the PUF verification value through the PUF function, the vehicle user is allowed to log in to the on-board unit OBU.

[0096] Vehicle V i When user U wants to use the vehicle's on-board unit OBU to run this system, he must first log in to the system. The entire login process is as follows:

[0097] Step L-1: User U enters the user's ID on the interface of the on-board unit OBU i And the vehicle key PW i .

[0098] Step L-2: Vehicle V i The on-board unit OBU uses the stored random number b to calculate the hash value h(PW i ⊕b), and use its own PUF function to calculate Q i '=PUF(ID i ||h(PW i ⊕b)).

[0099] Then, the on-board unit OBU will i 'With the Q stored by yourself i Compare them, if they are equal, then allow the user to perform various subsequent authentication operations. Otherwise, prompt the user that the user identity identifier and password entered are wrong, and remind the user to re-enter.

[0100] Step 4: Authentication between the vehicle's onboard unit OBU and the roadside unit RSU: Roadside unit RSU j The legitimacy of the on-board unit OBU is verified by verifying the authentication parameters, PUF function and PUF verification value of the on-board unit OBU, and the communication key is calculated using the secret value, the identity identifier of the on-board unit OBU and the vehicle key.

[0101] Roadside Unit RSU j After being deployed at a fixed location on the roadside, it will continue to broadcast its public key PK at a set time interval. RAnd other relevant information such as location. i Drive to the roadside unit RSU j After the coverage area is reached, you first need to contact the roadside unit RSU j Communicate and authenticate each other. After authentication, they can communicate and exchange messages and other aspects. i On-board unit OBU and roadside unit RSU j The steps for mutual authentication between the two parties are detailed below.

[0102] Step A-RV1: Vehicle V i The on-board unit OBU uses a random number generation function to generate a random number r vi ∈Z q * , and use the instant to generate a timestamp T i , and calculate:

[0103] RPK vi =r vi ·P,

[0104] E i =H(r vi ·PK R ),

[0105]

[0106] Token i =H(r vi ·TPK)⊕(Cert i ||T i );

[0107] Among them, E i For vehicle V i Temporary communication key with the roadside unit RSU. RPK vi is the temporary key E i A component used by roadside units to construct temporary communication keys. i Token i Together as a vehicle V i Authentication credentials used to verify vehicle V i the legitimacy of.

[0108] Then, the vehicle V i The on-board unit OBU generates a message {F i ,Token i ,RPK vi ,T i} and transmit the message to the roadside unit RSU via wireless j .

[0109] Step A-RV2: Upon receiving the message {F i ,Token i ,RPK vi ,T i}After that, the roadside unit RSU j First, by judging T c -T i ≤ΔT is established to determine the timestamp T i freshness. Among them, T c Roadside Unit RSU j The time when the message is received, △T refers to the maximum time interval that the system can allow. If the timestamp T i If the conditions are met, the roadside unit RSU j Calculate intermediate variables: E i '=H(s R ·RPK vi ), And extract the value from it Authentication Parameter C i and timestamp T i .

[0110] Subsequently, the roadside unit RSU j Calculate authentication parameters And judge equation C i '=C i Is it true? If the equation is true, then the roadside unit RSU j Consider vehicle V i For legal cars, and calculate the intermediate variables:

[0111] H i =ID i ⊕h(PW i ⊕b)⊕x⊕T j ,

[0112]

[0113] Among them, T j Roadside Unit RSU j Then, the roadside unit RSU j The message {L i ,T j}Send to vehicle V i , and calculate SK ji =h(H i ⊕T i ) as its relationship with the vehicle V i The key for subsequent communication with the on-board unit OBU. If equation C i '=C iIf not, the authentication process is terminated and the other party is informed.

[0114] Step A-RV3: Upon receiving the message {L i ,T j}, the vehicle V i The on-board unit OBU first uses a similar method in step A-RV2 to determine the timestamp T j If the timestamp T j If the conditions are met, then the vehicle V i The on-board unit OBU calculates the intermediate variable L i ⊕E i And extract the ID from it i ⊕h(PW i ⊕b)⊕x, and then calculate the intermediate variable:

[0115] D i '=h(ID i ⊕h(PW i ⊕b)⊕x),

[0116] R i '=PUF(D i ').

[0117] Then, the vehicle V i The on-board unit OBU judgment equation R i '=R i Is it true? If they are equal, then the vehicle V i The on-board unit OBU considers RSU j is a legal roadside unit. And calculate the communication key used by both parties for communication: SK ij =h(ID i ⊕h(PW i ⊕b)⊕x⊕T i ⊕T i ). If the equation R i '=R i If it is not true, then the roadside unit RSU j Not a legal roadside unit, vehicle V i Terminate the authentication process and inform the other party.

[0118] SK ij With SK ji The roadside units RSU of the two communicating parties j With vehicle V i Independently generated. It is not difficult to find SK ij =SK ji , the derivation process is as follows:

[0119] SK ij =h(IDi ⊕h(PW i ⊕b)⊕x⊕T i ⊕T i )

[0120] =h(H i ⊕T i )

[0121] =SK ji .

[0122] The core idea here is to use the non-clonable property of the physical PUF function. Only the PUF function of a specific vehicle can be used for a specific value D. i , in order to calculate the unique corresponding value R i The entire authentication process between the vehicle's onboard unit OBU and the roadside unit RSU is as follows: Figure 4 shown.

[0123] Step 5. Authentication of on-board units between vehicles: The on-board unit of one vehicle generates a temporary private key and public key using a random number generation function and a base point P, and sends the public key to the on-board unit of another vehicle. The on-board unit of the other vehicle verifies the freshness of the message through a timestamp, verifies the legitimacy of a vehicle through a secure hash function and authentication parameters, and generates a communication key II at the same time.

[0124] Before vehicles communicate with each other, they need to verify each other's legitimacy and negotiate secure communication keys to ensure the security of messages transmitted during the communication process. Without loss of generality, assume that the two parties in communication are vehicles V m With vehicle V n The specific steps of the entire authentication are as follows:

[0125] Step A-VV1: Vehicle V m The on-board unit OBU first uses a random number generation function to generate a random number r vm ∈Z q * As its temporary key, it then uses the random number r vm Calculate the corresponding public key RPK vm =r vm ·P. Subsequently, vehicle V m Construct the message {hello,RPK vm ,T1} and send the message to vehicle V wirelessly n . Hello represents a greeting packet, which is used for the first call to establish a connection.

[0126] Step A-VV2: After receiving the above message, vehicle V nThe vehicle-mounted unit OBU first checks the freshness of the timestamp T1 (in a similar manner to step A-RV2). If the timestamp T1 meets the freshness requirement, the vehicle V n The on-board unit OBU uses a random number generation function to generate a random number r vn ∈Z q * And calculate the intermediate variables:

[0127] RPK vn =r vn ·P,

[0128] M1=H(r vn ·RPK vm )⊕(h(ID n )||Cert n ||T2),

[0129] Token vn =H(r vn ·TPK)⊕(Cert n ||T2),

[0130] Wherein, T2 is the timestamp formed by the instant when the above formula is calculated.

[0131] Then, the vehicle V n Construct message {M1,Token vn ,RPK vn ,T2} and send the message to the vehicle V wirelessly m .

[0132] Step A-VV3: Upon receiving the message {M1,Token vn ,RPK vn ,T2}, vehicle V m The on-board unit OBU calculates the hash value H(r vm ·RPK vn )⊕M1 to extract the parameter h(ID n ), Cert n , timestamp T2 and use a similar method to step A-RV2 to determine the freshness of timestamp T2. If timestamp T2 meets the freshness requirement, continue to verify equation h(ID n )·Cert m =h(ID m )·Cert n Is it true? If the equation is true, the vehicle V m The on-board unit OBU thinks that the vehicle V n For legal vehicles, and calculate the intermediate variables:

[0133] M2=H(rvm ·RPK vn )⊕(h(ID m )||Cert m ||T3),

[0134] Token vm =H(r vm ·TPK)⊕(Cert m ||T3),

[0135] SK mn =H(h(T3)·h(ID m )·Cert n ).

[0136] If the equation C i '=C i If not, the authentication process is terminated and the vehicle V is notified n Otherwise, perform the following operations.

[0137] Then, the vehicle V m Generate message {M2,Token vm ,T3} and send the message to the vehicle V by wireless n At the same time, SK mn As a vehicle V m The vehicle-mounted unit OBU and vehicle V n The communication key between them.

[0138] Step A-VV4: After receiving the above message, vehicle V n By calculating H(r vn ·RPK vm )⊕M2 and extract h(ID m ), Cert m , T3. Then, vehicle V n First, determine the freshness of timestamp T3. If timestamp T3 meets the freshness requirement, then continue to verify h(ID m )·Cert n =h(ID n )·Cert m Is it true? If the equation is true, then the vehicle V n Consider vehicle V m For legal cars.

[0139] Then, the vehicle V n Calculate SK nm =H(h(T3)·h(ID n )·Cert m ) and SK nm As its Vm The communication key between them. m )·Cert n =h(ID n )·Cert m If it is established, it is not difficult to find the communication key SK mn and SK nm The entire authentication process between vehicles is as follows Figure 5 shown.

[0140] Step 6: Tracking the real identity of the vehicle: The trust agency TA verifies the identity of the vehicle's on-board unit OBU by extracting the authentication parameters and timestamp from the identity parameters in the vehicle's on-board unit OBU.

[0141] In the method proposed by the present invention, the trust agency TA can obtain the message sent by the vehicle at any time and obtain the real identity of the vehicle therefrom. The specific method is as follows:

[0142] During the authentication process of the vehicle's on-board unit OBU and RSU, the vehicle V i The message sent by the on-board unit OBU contains the parameter Token i This parameter is mainly used by the trust agency TA to i The specific tracking method is described as follows: the trust institution TA obtains the message {F i ,Token i ,RPK vi ,T i}, use your own private key s to calculate the hash value H(s·RPK vi )⊕Token i And extract the Cert from it i ' and T i '. Then compare T i 'With timestamp T i Are they consistent? If they are consistent, directly use the timestamp T i 'Query the vehicle list VTL of the backend database server to obtain the corresponding vehicle ID i , and then the vehicle list VTL can be used to manage the vehicles.

[0143] During the vehicle-to-vehicle authentication process, the trust agency TA can obtain the message of any vehicle and obtain the corresponding value (Token vn or Token vm ) and use its own private key s to calculate the corresponding certificate, namely the authentication parameter Cert n or Cert mThen, the authentication parameters are used to query the vehicle list VTL of the backend database server to obtain the corresponding vehicle identity identifier (ID n or ID m ), and then use the data list to manage the vehicle accordingly.

[0144] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A vehicle authentication method with privacy protection based on PUF, characterized in that: The steps are as follows: Step 1: System initialization: Select an on-board unit OBU with PUF function and an elliptic curve. The trust agency TA selects a base point and two secure hash functions on the elliptic curve. The trust agency TA uses a random number generation algorithm to generate a random number as its own private key, and uses the private key and the base point to generate its own public key. The trust agency TA uses a random number generation algorithm to generate two random numbers as secret values ​​and save them. Step 2, registration of the on-board unit OBU: the on-board unit OBU generates a PUF verification value and an intermediate variable through the identity identifier, vehicle key, PUF function, base point P, two secret values ​​and a secure hash function, and communicates with the trust agency TA. The trust agency TA generates the authentication parameters of the vehicle, transmits them to the on-board unit OBU through a secure communication channel and saves them in the vehicle list VTL; Registration of the roadside unit RSU: the trust agency TA generates the private key of the roadside unit RSU through a random number generation algorithm, generates the public key of the roadside unit RSU through the private key of the roadside unit RSU and the base point P, and transmits the private key and public key of the roadside unit RSU to the roadside unit RSU; Step 3: The vehicle user logs in to the on-board unit OBU: The vehicle user logs in to the on-board unit OBU through the identity identifier and the vehicle key. After the on-board unit OBU determines the correctness of the PUF verification value through the PUF function, the vehicle user is allowed to log in to the on-board unit OBU; Step 4: Authentication between the vehicle's onboard unit OBU and the roadside unit RSU: Roadside unit RSU j Verify the legitimacy of the on-board unit OBU by verifying the authentication parameters, PUF function and PUF verification value of the on-board unit OBU, and calculate the communication key I using the secret value, the identity identifier of the on-board unit OBU and the vehicle key; Step 5. Authentication of the on-board unit (OBU) between vehicles: The on-board unit of one vehicle generates a temporary private key and public key using a random number generation function and a base point P, and sends the public key to the on-board unit of another vehicle. The on-board unit of the other vehicle verifies the freshness of the message through a timestamp, verifies the legitimacy of a vehicle through a secure hash function and authentication parameters, and generates a communication key II.

2. The vehicle authentication method with privacy protection based on PUF according to claim 1, characterized in that: The elliptic curve is an elliptic curve E selected over a finite field GF(p) consisting of a large prime number p. p (a,b):y1 2 =x1 3 +ax1+b and satisfies 4a 3 +27b 2 ≠0(mod p), where a, b∈Z q * is the constant of the elliptic curve, x1 and y1 are the independent variable and dependent variable of the elliptic curve; the base point P is the trust institution TA on the elliptic curve E p A point of order q is selected on (a, b); the two secure hash functions are respectively the secure hash function h(·) and the secure hash function H(·), and the secure hash function From 0,1 string to finite field of order q Hash function; secure hash function H:E p (a,b)→{0,1} l For the elliptic curve E p The trust institution TA generates two random numbers x and The method for the trust institution TA to generate its own private key and public key is as follows: the trust institution TA generates a random number using a random number generation algorithm As its own private key, use the base point P and the private key s to calculate the corresponding public key TPK = s·P; the trust institution TA uses the public parameters {E p (a,b),q,P,h(·),H(·),TPK} are made public.

3. The vehicle authentication method with privacy protection based on PUF according to claim 2 is characterized in that: The method for registering the on-board unit OBU is: Step VR1: Vehicle V i The on-board unit OBU selects a unique ID i And the corresponding key PW i ; Vehicle V i Generate random numbers using random number generation algorithms And calculate the hash value And PUF verification value Vehicle V i The on-board unit OBU generates a message The message is then passed to the trusted authority TA through a secure communication channel; where PUF(·) is the physical unclonable function owned by the on-board unit OBU, || is the concatenation operator of two strings, is an XOR operation; Step VR2: Upon receiving the message After that, the trust agency TA calculates the intermediate variable And the message {D i } is transmitted to the vehicle V through a secure communication channel i On-board unit OBU; vehicle V i The on-board unit OBU calculates the value R based on the received message i =PUF(D i ) and set the value R i Send back to the trusted institution TA; Step VR3: Upon receiving the value R i Afterwards, the trust authority TA calculates the authentication parameters: Cert i =h(R i )·x·P Among them, C i , Cert i Represents vehicle V i Authentication parameters of the on-board unit OBU; Then, the trusted authority TA generates a message {C i ,Cert i } and pass the message to the vehicle V through a secure communication channel i The on-board unit OBU; the trust authority TA builds a record <ID i ,Cert i ,C i >, and store the record in the vehicle list VTL of the backend database server; Step VR4: Vehicle V i The on-board unit OBU receives the message {C i ,Cert i }, the vehicle V i The on-board unit OBU will have the parameters <b,Q i ,C i ,Cert i >Stored in its tamper-proof device TPD.

4. The vehicle authentication method with privacy protection based on PUF according to claim 2 or 3, characterized in that: The registration method of the roadside unit RSU is: Step RR1: The trusted institution TA generates a random number using a random number generation algorithm And use it as a roadside unit RSU j The private key of the roadside unit is used to calculate the RSU j Public key: PK R =s R ·P; Step RR2: Then, the trusted authority TA calculates the intermediate variable F j =s R ·x·P and set the parameter <F j ,s R ,x,PK R >Store in roadside unit RSU j In the tamper-proof device TPD; Trust institution TA will roadside unit RSU j Parameters of <F j ,s R ,x,PK R >Roadside equipment table stored in the backend database server.

5. The vehicle authentication method with privacy protection based on PUF according to claim 3 is characterized in that: The method for the vehicle user to log in to the on-board unit OBU is: Step L-1: User U enters the user's ID on the interface of the on-board unit OBU i And the vehicle key PW i ; Step L-2: Vehicle V i The on-board unit OBU uses the stored random number b to calculate the hash value h(PW i ⊕b), and use its own PUF function to calculate the intermediate variable Q i '=PUF(ID i ||h(PW i ⊕ b)); The on-board unit OBU converts the intermediate variable Q i 'Verify the stored PUF value Q i If they are equal, user U is allowed to perform subsequent authentication operations; otherwise, vehicle V i The OBU prompts the user to enter the ID i And the vehicle key PW i Error, prompt the user to re-enter.

6. The vehicle authentication method with privacy protection based on PUF according to claim 4, characterized in that: When the vehicle V i Drive to the roadside unit RSU j After the coverage area, the vehicle V i On-board unit OBU and roadside unit RSU j The authentication method between them is: Step A-RV1: Vehicle V i The on-board unit OBU uses a random number generation function to generate a random number r vi ∈Z q * , and use the instant to generate a timestamp T i Calculate intermediate variables: RPC vi =r vi ·P, E i =H(r vi ·PK R ), Among them, E i For vehicle V i Temporary communication key with roadside unit RSU; RPK vi is the temporary key E i A component used by roadside units to construct temporary communication keys; F i Token i Together as a vehicle V i Authentication credentials used to verify vehicle V i Legality of vehicle V i The on-board unit OBU generates a message {F i ,Token i ,RPK vi ,T i } and transmit the message to the roadside unit RSU via wireless j ; Step A-RV2: Receive message {F i ,Token i ,RPK vi ,T i }After that, the roadside unit RSU j Determine timestamp T i If the timestamp T i Meet the freshness condition, roadside unit RSU j Calculate intermediate variables: E i '=H(s R ·RPK vi )and And extract the value from it Authentication Parameter C i and timestamp T i ; Roadside Unit RSU j Calculate authentication parameters And judge equation C i '=C i Is it true? If the equation is true, the roadside unit RSU j Consider vehicle V i For legal cars, and calculate the intermediate variables: Among them, T j Roadside Unit RSU j The new timestamp of Roadside Unit RSU j The message {L i ,T j }Send to vehicle V i The on-board unit OBU and calculate As its V i The key for subsequent communication with the on-board unit OBU; Step A-RV3: Receive message {L i ,T j }, the vehicle V i The on-board unit OBU determines the timestamp T j If the timestamp T j If the freshness condition is met, then the vehicle V i The on-board unit OBU calculates the intermediate variables and extract from it Then calculate the intermediate variables: R i '=PUF(D i '); Vehicle V i The on-board unit OBU judgment equation R i '=R i Is it true? If the equation is true, then the vehicle V i The on-board unit OBU is considered as the roadside unit RSU j For a legitimate roadside unit, and calculate the communication key used by both parties to communicate 7. The vehicle authentication method with privacy protection based on PUF according to claim 6 is characterized in that: The method for authenticating the on-board unit OBU between vehicles in step 5 is: Step A-VV1: Vehicle V m The on-board unit OBU uses a random number generation function to generate a random number r vm ∈Z q * As its temporary key, use the random number r vm Calculate the corresponding public key RPK vm =r vm ·P; Vehicle V m The on-board unit OBU constructs the message {hello,RPK vm ,T1} and send the message to vehicle V wirelessly n ; Among them, hello represents a greeting packet, which is used for the first call to establish a connection; Step A-VV2: Upon receiving the message {hello,RPK vm ,T1}, vehicle V n The vehicle-mounted unit OBU checks the freshness of the timestamp T1. If the timestamp T1 meets the freshness requirement, the vehicle V n The on-board unit OBU uses a random number generation function to generate a random number r vn ∈Z q * And calculate the intermediate variables: RPC vn =r vn ·P, Wherein, T2 is the timestamp formed by the instant when the above intermediate variable is calculated; Then, the vehicle V n The on-board unit OBU constructs the message {M1,Token vn ,RPK vn ,T2} and send the message to the vehicle V wirelessly m ; Step A-VV3: Upon receiving the message {M1,Token vn ,RPK vn ,T2}, vehicle V m The on-board unit OBU calculates the hash value To extract the parameter h(ID n ), authentication parameters Cert n , timestamp T2; determine the freshness of timestamp T2. If timestamp T2 meets the freshness requirement, verify equation h(ID n )·Cert m =h(ID m )·Cert n Is it true? If the equation is true, the vehicle V m The on-board unit OBU thinks that the vehicle V n For legal vehicles, and calculate the intermediate variables: SK mn =H(h(T3)·h(ID m )·Cert n ); Vehicle V m The on-board unit OBU generates a message {M2,Token vm ,T3} and send the message to the vehicle V by wireless n ; At the same time, SK mn As a vehicle V m The on-board unit OBU and vehicle V n The communication key between the on-board units OBU; Step A-VV4: Upon receiving the message {M2,Token vm ,T3}, vehicle V n The on-board unit OBU calculates the hash value And extract h(ID m ), authentication parameters Cert m , timestamp T3; vehicle V n The on-board unit OBU determines the freshness of the timestamp T3. If the timestamp T3 meets the freshness requirement, it verifies h(ID m )·Cert n =h(ID n )·Cert m Is it true? If the equation is true, then the vehicle V n The on-board unit OBU thinks that the vehicle V m For legal cars; vehicles V n The on-board unit OBU calculates SK nm =H(h(T3)·h(ID n )·Cert m ) and SK nm As its V m The communication key between them.

8. The vehicle authentication method with privacy protection based on PUF according to claim 6 or 7, characterized in that: The random number generation algorithm is the Mersenne Twister algorithm; the identity identifier ID i Using Vehicle V i At least one of the engine number, frame number or production time is generated by a secure hash function; the method for determining the freshness of the timestamp is: determining T c -T≤ΔT, where T c Indicates the time when the message is received, △T refers to the maximum time interval that the system can allow, and T represents the instant when the message is sent and is the timestamp T i , timestamp T j , timestamp T1, timestamp T2 or timestamp T3.

9. The vehicle authentication method with privacy protection based on PUF according to claim 8, characterized in that: It also includes tracking of the vehicle's true identity: the trust authority TA verifies the identity of the vehicle's on-board unit OBU by extracting authentication parameters and timestamps from identity parameters in the vehicle's on-board unit OBU.

10. The vehicle authentication method with privacy protection based on PUF according to claim 9, characterized in that: The tracking method is as follows: the trust institution TA obtains the message {F i ,Token i ,RPK vi ,T i }, use your own private key s to calculate the hash value And extract the parameter Cert from it i ' and T i ', compare T i 'With timestamp T i Are they consistent? If they are consistent, directly use the timestamp T i ' or parameter Cert i 'Query the vehicle list VTL of the backend database server to obtain the corresponding vehicle ID i .

Images