Vehicle similarity-based pseudonym replacement method for Internet of Vehicles

Abstract

The invention provides a kana replacement method based on vehicle similarity for the Internet of Vehicles, and relates to the technical field of wireless network security, a kana replacement system is used for obtaining a vehicle kana, and the kana replacement system comprises three layers of structures: a cloud layer, a fog layer and an edge layer. The pseudonym replacement method can be divided into a vehicle pseudonym acquisition stage, a pseudonym replacement area determination stage and a vehicle cooperation pseudonym replacement stage. According to the method, potential attacking and tracking capabilities of malicious attackers are fully considered, and a dynamic region division strategy based on vehicle similarity is supported. The method supports a kana replacement scheme independent of the road infrastructure (RSU), can improve the efficiency of kana replacement, reduces the dependence on the road infrastructure (RSU), improves the anonymity and safety of the system, and has a good application value.

Description

Technical Field

[0001] The present invention relates to the technical field of wireless network security, and in particular to a pseudonym replacement method based on vehicle similarity for an Internet of Vehicles. Background Art

[0002] In recent years, with the continuous development of new generation information technologies such as 5G and the Internet of Things, vehicular ad-hoc networks (VANETs) are rapidly becoming popular and applied. VANETs can improve driving safety, improve driving experience, enhance vehicle management efficiency, and bring many conveniences to people's travel life. VANETs refers to a huge interactive network that connects cars, transportation facilities, pedestrians, and various service platforms through Internet technology to achieve information sharing and interaction. The VANETs system architecture based on fog computing consists of a cloud layer, a fog layer, and an edge layer. The cloud layer's trusted authority (TA) is deployed on the government's cloud server; the fog layer includes the fog layer trusted nodes (R TA ), which is located between the cloud layer and the edge layer and is managed by the cloud layer; the edge layer mainly consists of vehicles, roadside units (RSU) and eavesdropping devices deployed by attackers, and each vehicle is equipped with an on-board unit (OBU). There are two main communication modes in VANETs, ​​namely vehicle-to-vehicle communication (V2V) and vehicle-to-infrastructure communication (V2I). OBU sends the messages generated by its sensors to other vehicles or RSU. RSU has the function of forwarding messages and is responsible for forwarding messages between vehicles and TA. TA, as the administrator of the entire system, is responsible for the security management of the system. The information transmitted in VANETs includes a large amount of personal information, including the owner's identity information, vehicle location information, and vehicle trajectory information. This information may be illegally stolen by attackers during transmission, and the exposure of vehicle location information is bound to pose a serious threat to the personal and property safety of the owner.

[0003] Protecting user data security and privacy has become an important task for VANETs. In order to prevent attackers from tracking the real identity of users through the communication data of vehicles, pseudonyms can be used to replace the real identity of vehicles for communication, thereby protecting the identity privacy of users. However, if a vehicle uses a pseudonym for a long time, attackers will establish an association between the pseudonym and the real identity of the vehicle, so the pseudonym needs to be replaced at the right time and in the right place. In response to this problem, many solutions have been proposed to achieve pseudonym replacement, mainly including pseudonym replacement strategies based on mixed zones and pseudonym replacement strategies based on mixed contexts. Among them, pseudonym replacement strategies based on mixed zones usually perform pseudonym replacement in busy traffic locations such as intersections and parking lots in cities. This strategy requires full coverage of RSUs and is overly dependent on RSUs. Although the pseudonym replacement strategy based on mixed contexts allows vehicles to independently decide when and where to change their pseudonyms, this strategy faces the challenges of high latency and high cost of pseudonym management. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention provides a pseudonym replacement method based on vehicle similarity for the Internet of Vehicles; the vehicle first obtains a pseudonym in the system initialization stage, and determines the pseudonym replacement area by calculating the driving similarity, and multiple vehicles cooperate to exchange pseudonyms, reducing the dependence on RSU and eliminating its limitations.

[0005] A pseudonym replacement method based on vehicle similarity for Internet of Vehicles includes the following steps:

[0006] Step S1: Obtain vehicle pseudonym;

[0007] Specifically, a pseudonym replacement system is used to obtain a pseudonym for a vehicle, and the pseudonym replacement system includes a three-layer structure: a cloud layer, a fog layer, and an edge layer;

[0008] Step S100: Before officially joining VANETs, ​​the vehicle registers at the cloud TA;

[0009] Step S101: The cloud layer TA equips the vehicle with a private key SK, a public key PK, and a long-term pseudonym PID L And the certificate Cert Ri ;

[0010] Step S102: The vehicle enters the fog layer R TA management area and receives R TA When the short-term pseudonym distribution is broadcast periodically, the message msg is sent to the nearest roadside unit RSU c = {Req s ||PID L ||T REP}, where Req s is a short-term pseudonymous request identifier, PIDL is a long-standing pseudonym for the vehicle, T REP is the current timestamp;

[0011] Step S103: The RSU verifies the real identity of the vehicle;

[0012] Step S104: If the verification is successful, the RSU sends msg c Forward to R TA ; If verification fails, the message is discarded directly;

[0013] Step S105: R TA After completing the authentication process, a short-term pseudonym set PID is generated based on the specific needs of the vehicle S ={PID1,PID2,PID3...PID i}, PID i For the i-th short-term pseudonym, RSU sets PID S Send to vehicle;

[0014] Step S106: The vehicle selects PID1 as the initial pseudonym. When the usage time of PID1 reaches the set threshold β, the next short-term pseudonym, PID2, is used to replace PID1. If the vehicle leaves the current R TA If the coverage range is greater than , step S102 is executed;

[0015] Step S2: Determine the pseudonym replacement area;

[0016] Step S200: When the number of pseudonyms used by the vehicle exceeds the set critical value and the short-term pseudonym currently in use is about to expire, the vehicle Va broadcasts a request message msg = {Req i ||PID i ||T REP}, seeking collaboration with other vehicles, where Req i Is the request identifier for starting group key encryption, PID i is the short pseudonym for vehicle Va, T REP is the current timestamp;

[0017] Step S201: V Range The vehicle in receives the request message msg from vehicle Va and verifies the PID of vehicle Va. i Is it legal? If the PID of vehicle Va i If it is legal, then execute step S202; otherwise skip this step; where V Range It is the set of all vehicles within the communication coverage of vehicle Va;

[0018] Step S202: V RangeThe vehicle set V that has the intention to change its pseudonym change Calculate the speed similarity between the vehicle Va and itself; the speed similarity is calculated as follows:

[0019] The speed similarity sim between vehicle Va and vehicle Vb v As shown below:

[0020]

[0021] Δv=v max -v min (v max ,v min ∈V change )

[0022] where v i is the speed of vehicle Va, v j is the speed of vehicle Vb, vehicle Vb∈V change , v max and v min Yes V change Maximum speed and minimum speed;

[0023] Step S203: V change The vehicle in calculates the direction similarity between itself and vehicle Va; the direction similarity calculation method is as follows:

[0024] The direction similarity sim between vehicle Va and vehicle Vb D As shown below:

[0025]

[0026] Δd=d max -d min (d max ,d min ∈V change )

[0027] where d i is the moving direction of Va along the horizontal coordinate, d j is the moving direction of vehicle Vb along the horizontal coordinate, Δd is the difference between the maximum and minimum values ​​of the direction range of all vehicles, that is, the total span of the direction change;

[0028] Step S204: V change The vehicle in further calculates the position similarity between itself and vehicle Va; the position similarity calculation method is as follows:

[0029] Calculate the position similarity sim between vehicle Va and vehicle Vb L :

[0030]

[0031] Where (x i ,y i ) is the position coordinate of vehicle Va, (x j ,y j ) is the position coordinate of vehicle Vb, ΔL represents the maximum physical distance between any two vehicles in the set;

[0032] Step S205: V change The vehicle in calculates the driving state similarity between itself and vehicle Va, and determines whether to respond to the cooperation of vehicle Va to perform the pseudonym change request based on the driving state similarity; the driving state similarity calculation method is as follows:

[0033] Calculate the driving state similarity sim between vehicle Va and vehicle Vb:

[0034]

[0035] Among them, w1, w2, w3 are weight factors, and all are greater than 0; vehicle Vb sends a message msg to vehicle Va Vb ={sim||T REP ||PID Vb}, where sim is the driving state similarity between Va and Vb, T REP is the current timestamp, PID Vb is a short-term pseudonym for vehicle Vb;

[0036] Step S206: Vehicle Va receives responses from surrounding vehicles and verifies the legitimacy of the responding vehicle identity; if the responding vehicle identity is legitimate, execute step S207; otherwise skip this step;

[0037] Step S207: Vehicle Va calculates the similarity between itself and the responding vehicle. If the calculated result is consistent with the similarity provided by the responding vehicle, the responding vehicle is a legitimate vehicle; otherwise, the malicious behavior is reported to TA through the RSU;

[0038] Step S208: Vehicle Va sets a minimum number threshold λ for vehicles participating in the short-term pseudonym replacement. If the number of vehicles s actually participating in the pseudonym replacement exceeds the threshold λ, vehicle Va selects the first λ legal vehicles with the highest driving state similarity to establish a λ-mixing zone; if the number of vehicles s actually participating in the pseudonym replacement does not exceed the threshold λ, each participating vehicle broadcasts to neighboring nodes pseudonym change notifications to establish a k-anonymity mixed zone;

[0039] The λ-mixing zone and the k-anonymous mixing zone are collectively referred to as mixing zones;

[0040] Step S209: Vehicle Va generates a group key ka for the vehicle in the mixed zone, and then generates a message Ga based on ka= <PID i ,ka,T Ga >, where PID i is the short-term pseudonym currently used by Va, T Ga is the current timestamp and uses the private key SK Va Sign the message Ga to get SIG(Ga;SK Va );

[0041] Step S210: Vehicle Va uses the public key PK of the vehicle in the mixed zone Vchange Encrypt Ga to get the ciphertext C = E (PK Vchange ,Ga), then C and SIG(Ga;SK Va ) are sent to vehicles in the mixed zone respectively;

[0042] Step S211: V change The vehicle in the game uses its own private key SK Vchange Decrypt the ciphertext C and verify SIG(Ga;SK Va ), and then get ka, then V change The vehicles in the group will build an encrypted communication group with the vehicle Va, which is called the hybrid name-changing zone;

[0043] Step S3: Vehicles cooperate to change pseudonyms;

[0044] Step S301: During the validity period of the mixed name change zone, multiple vehicles simultaneously apply for a new round of pseudonym changes and adjust the driving speed and trajectory;

[0045] The validity period of the mixed name change zone means that when the number of pseudonyms used by a vehicle exceeds a set critical value, the system will send a signal indicating that the vehicle should go through a new round of short-term pseudonym application process;

[0046] Step S301: The vehicle encrypts the pseudonym using the established session key ka and sends the changed pseudonym to other vehicles;

[0047] Step S302: Fog layer R TA Update the mapping relationship between long-term pseudonyms and the latest round of short-term pseudonyms.

[0048] The beneficial effects of adopting the above technical solution are:

[0049] The present invention provides a pseudonym replacement method based on vehicle similarity for vehicle networking. Compared with the prior art, the present invention eliminates the reliance on RSU, thereby avoiding the burden of RSU in storage and calculation. The present invention adopts a method of calculating vehicle similarity to determine the exchange mixing area, eliminating the problem of allocating storage space for a large number of pseudonyms, thereby realizing efficient pseudonym replacement while protecting the privacy of vehicle location. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 The figure is an overall flow chart of the pseudonym replacement method based on vehicle similarity of the present invention. DETAILED DESCRIPTION

[0051] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0052] A pseudonym replacement method based on vehicle similarity for Internet of Vehicles, such as Figure 1 As shown, the following steps are included:

[0053] Step S1: Obtain vehicle pseudonym;

[0054] Specifically, a pseudonym replacement system is used to obtain a pseudonym for a vehicle, and the pseudonym replacement system includes a three-layer structure: a cloud layer, a fog layer, and an edge layer;

[0055] Step S100: Before officially joining VANETs, ​​the vehicle registers at the cloud TA;

[0056] Step S101: The cloud layer TA equips the vehicle with a private key SK, a public key PK, and a long-term pseudonym PID L And the certificate Cert Ri ;

[0057] Step S102: The vehicle enters the fog layer R TA management area and receives R TA When the short-term pseudonym distribution is broadcast periodically, the message msg is sent to the nearest roadside unit RSU c = {Req s ||PID L ||T REP}, where Req s is a short-term pseudonymous request identifier, PID L is a long-standing pseudonym for the vehicle, T REP is the current timestamp;

[0058] Step S103: The RSU verifies the real identity of the vehicle;

[0059] Step S104: If the verification is successful, the RSU sends msg c Forward to R TA ; If verification fails, the message is discarded directly;

[0060] Step S105: R TA After completing the authentication process, a short-term pseudonym set PID is generated based on the specific needs of the vehicle S ={PID1,PID2,PID3...PID i}, PID i For the i-th short-term pseudonym, RSU sets PID S Send to vehicle;

[0061] Step S106: The vehicle selects PID1 as the initial pseudonym. When the usage time of PID1 reaches the set threshold β, the next short-term pseudonym, PID2, is used to replace PID1. If the vehicle leaves the current R TA If the coverage range is greater than , step S102 is executed;

[0062] Step S2: Determine the pseudonym replacement area;

[0063] Step S200: When the number of pseudonyms used by the vehicle exceeds the set critical value and the short-term pseudonym currently in use is about to expire, the vehicle Va broadcasts a request message msg = {Req i ||PID i ||T REP}, seeking collaboration with other vehicles, where Req i Is the request identifier for starting group key encryption, PID i is the short pseudonym for vehicle Va, T REP is the current timestamp;

[0064] Step S201: V Range The vehicle in receives the request message msg from vehicle Va and verifies the PID of vehicle Va. i Is it legal? If the PID of vehicle Va i If it is legal, then execute step S202; otherwise skip this step; where V Range It is the set of all vehicles within the communication coverage of vehicle Va;

[0065] Step S202: V Range The vehicle set V that has the intention to change its pseudonym change Calculate the speed similarity between the vehicle Va and itself; the speed similarity is calculated as follows:

[0066] The speed similarity sim between vehicle Va and vehicle Vb v As shown below:

[0067]

[0068] Δv=v max -v min (v max ,v min ∈V change )

[0069] where v i is the speed of vehicle Va, v j is the speed of vehicle Vb, vehicle Vb∈V change , v max and v min Yes V change Maximum speed and minimum speed;

[0070] Step S203: V change The vehicle in calculates the direction similarity between itself and vehicle Va; the direction similarity calculation method is as follows:

[0071] The direction similarity sim between vehicle Va and vehicle Vb D As shown below:

[0072]

[0073] Δd=d max -d min (d max ,d min ∈V change )

[0074] where d i is the moving direction of Va along the horizontal coordinate, d j is the moving direction of vehicle Vb along the horizontal coordinate, Δd is the difference between the maximum and minimum values ​​of the direction range of all vehicles, that is, the total span of the direction change;

[0075] Step S204: V change The vehicle in further calculates the position similarity between itself and vehicle Va, and the position similarity calculation method is as follows:

[0076] Calculate the position similarity sim between vehicle Va and vehicle Vb L :

[0077]

[0078] Where (x i ,y i ) is the position coordinate of vehicle Va, (x j ,y j) is the position coordinate of vehicle Vb, ΔL represents the maximum physical distance between any two vehicles in the set;

[0079] Step S205: V change The vehicle in calculates the driving state similarity between itself and vehicle Va, and determines whether to respond to the cooperation of vehicle Va to perform the pseudonym change request based on the driving state similarity; the driving state similarity calculation method is as follows:

[0080] Calculate the driving state similarity sim between vehicle Va and vehicle Vb:

[0081]

[0082] Among them, w1, w2, w3 are weight factors, and all are greater than 0; vehicle Vb sends a message msg to vehicle Va Vb ={sim||T REP ||PID Vb}, where sim is the driving state similarity between Va and Vb, T REP is the current timestamp, PID Vb is a short-term pseudonym for vehicle Vb;

[0083] The driving state similarity selects position, speed and driving direction as three key indicators, which can be directly obtained from the beacon messages broadcast by the vehicle to accurately quantify the similarity of the vehicle driving state. Among them, w1, w2, and w3 are determined by the system designer based on the specific analysis of road and traffic conditions to reflect the relative importance of each similarity in the comprehensive similarity calculation.

[0084] Step S206: Vehicle Va receives responses from surrounding vehicles and verifies the legitimacy of the responding vehicle identity; if the responding vehicle identity is legitimate, execute step S207; otherwise skip this step;

[0085] Step S207: Vehicle Va calculates the similarity between itself and the responding vehicle. If the calculated result is consistent with the similarity provided by the responding vehicle, the responding vehicle is a legitimate vehicle; otherwise, the malicious behavior is reported to TA through the RSU;

[0086] Step S208: Vehicle Va sets a minimum number threshold λ for vehicles participating in the short-term pseudonym replacement. If the number of vehicles s actually participating in the pseudonym replacement exceeds the threshold λ, vehicle Va selects the first λ legal vehicles with the highest driving state similarity to establish an efficient and safe λ-mixing zone; if the number of vehicles s actually participating in the pseudonym replacement does not exceed the threshold λ, each participating vehicle broadcasts to neighboring nodes pseudonym change notifications to establish a k-anonymity mixed zone;

[0087] The λ-mixing zone and the k-anonymous mixing zone are collectively referred to as mixing zones;

[0088] Step S209: Vehicle Va generates a group key ka for the vehicle in the mixed zone, and then generates a message Ga based on ka= <PID i ,ka,T Ga >, where PID i is the short-term pseudonym currently used by Va, T Ga is the current timestamp and uses the private key SK Va Sign the message Ga to get SIG(Ga;SK Va );

[0089] Step S210: Vehicle Va uses the public key PK of the vehicle in the mixed zone Vchange Encrypt Ga to get the ciphertext C = E (PK Vchange ,Ga), then C and SIG(Ga;SK Va ) are sent to vehicles in the mixed zone respectively;

[0090] Step S211: V change The vehicle in the game uses its own private key SK Vchange Decrypt the ciphertext C and verify SIG(Ga;SK Va ), and then get ka, then V change The vehicles in the group will build an encrypted communication group with the vehicle Va, which is called the hybrid name-changing zone;

[0091] Step S3: Vehicles cooperate to change pseudonyms;

[0092] Step S301: During the validity period of the mixed name change zone, multiple vehicles simultaneously apply for a new round of pseudonym changes and adjust the driving speed and trajectory in a timely manner;

[0093] The validity period of the mixed name change zone means that when the number of pseudonyms used by a vehicle exceeds a set critical value, the system will send a signal indicating that the vehicle should go through a new round of short-term pseudonym application process;

[0094] Step S301: The vehicle encrypts the pseudonym using the established session key ka and sends the changed pseudonym to other vehicles;

[0095] Step S302: Fog layer R TA Update the mapping relationship between long-term pseudonyms and the latest round of short-term pseudonyms.

[0096] The above description is only a preferred embodiment of the present disclosure and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the embodiments of the present disclosure is not limited to the technical solutions formed by a specific combination of the above-mentioned technical features, but should also cover other technical solutions formed by any combination of the above-mentioned technical features or their equivalent features without departing from the above-mentioned inventive concept. For example, the above-mentioned features are replaced with the technical features with similar functions disclosed in the embodiments of the present disclosure (but not limited to) to form a technical solution.

Claims

1. A pseudonym replacement method based on vehicle similarity for Internet of Vehicles, characterized in that: The following steps are involved: Step S1: Obtain vehicle pseudonym; Step S2: Determine the pseudonym replacement area; Step S3: Vehicles cooperate to change pseudonyms.

2. The pseudonym replacement method based on vehicle similarity for Internet of Vehicles according to claim 1 is characterized in that: The step S1 specifically includes obtaining a pseudonym for the vehicle using a pseudonym replacement system, wherein the pseudonym replacement system includes a three-layer structure: a cloud layer, a fog layer, and an edge layer.

3. The pseudonym replacement method based on vehicle similarity for Internet of Vehicles according to claim 2 is characterized in that: The step S1 comprises the following steps: Step S100: Before officially joining VANETs, ​​the vehicle registers at the cloud TA; Step S101: The cloud layer TA equips the vehicle with a private key SK, a public key PK, and a long-term pseudonym PID L And the certificate Cert Ri ; Step S102: The vehicle enters the fog layer R TA management area and receives R TA When the short-term pseudonym distribution is broadcast periodically, the message msg is sent to the nearest roadside unit RSU c = {Req s ||PID L ||T REP }, where Req s is a short-term pseudonymous request identifier, PID L is a long-standing pseudonym for the vehicle, T REP is the current timestamp; Step S103: The RSU verifies the real identity of the vehicle; Step S104: If the verification is successful, the RSU sends msg c Forward to R TA ; If verification fails, the message is discarded directly; Step S105: R TA After completing the authentication process, a short-term pseudonym set PID is generated based on the specific needs of the vehicle S ={PID1, PID2, PID3...PID i }, PID i For the i-th short-term pseudonym, RSU sets PID S Send to vehicle; Step S106: The vehicle selects PID1 as the initial pseudonym. When the usage time of PID1 reaches the set threshold β, the next short-term pseudonym, PID2, is used to replace PID1. If the vehicle leaves the current R TA If the coverage range is greater than 100, step S102 is executed.

4. The pseudonym replacement method based on vehicle similarity for Internet of Vehicles according to claim 1 is characterized in that: The step S2 comprises the following steps: Step S200: When the number of pseudonyms used by the vehicle exceeds the set critical value and the short-term pseudonym currently in use is about to expire, the vehicle Va broadcasts a request message msg = {Req i ||PID i ‖|T REP }, seeking collaboration with other vehicles, where Req i Is the request identifier for starting group key encryption, PID i is the short pseudonym for vehicle Va, T REP is the current timestamp; Step S201: V Range The vehicle in receives the request message msg from vehicle Va and verifies the PID of vehicle Va. i Is it legal? If the PID of vehicle Va i If it is legal, then execute step S202; otherwise skip this step; where V Range It is the set of all vehicles within the communication coverage of vehicle Va; Step S202: V Range The vehicle set V that has the intention to change its pseudonym change Calculate the speed similarity between the vehicle Va and itself; the speed similarity is calculated as follows: The speed similarity sim between vehicle Va and vehicle Vb v As shown below: Δv=v max -v min (v max ,v min ∈V change ) where v i is the speed of vehicle Va, v j is the speed of vehicle Vb, vehicle Vb∈V change , v max and v min Yes V change Maximum speed and minimum speed; Step S203: V change The vehicle in calculates the direction similarity between itself and vehicle Va; the direction similarity calculation method is as follows: The direction similarity sim between vehicle Va and vehicle Vb D As shown below: Δd=d max -d min (d max ,d min ∈V change ) where d i is the moving direction of Va along the horizontal coordinate, d j is the moving direction of vehicle Vb along the horizontal coordinate, Δd is the difference between the maximum and minimum values ​​of the direction range of all vehicles, that is, the total span of the direction change; Step S204: V change The vehicle in further calculates the position similarity between itself and vehicle Va, and the position similarity calculation method is as follows: Calculate the position similarity sim between vehicle Va and vehicle Vb L : Where (x i ,y i ) is the position coordinate of vehicle Va, (x j ,y j ) is the position coordinate of vehicle Vb, ΔL represents the maximum physical distance between any two vehicles in the set; Step S205: V change The vehicle in calculates the driving state similarity between itself and vehicle Va, and determines whether to respond to the cooperation of vehicle Va to perform the pseudonym change request based on the driving state similarity; the driving state similarity calculation method is as follows: Calculate the driving state similarity sim between vehicle Va and vehicle Vb: Among them, w1, w2, w3 are weight factors, and all are greater than 0; vehicle Vb sends a message msg to vehicle Va Vb ={sim||T REP ||PID Vb }, where sim is the driving state similarity between Va and Vb, T REP is the current timestamp, PID Vb is a short-term pseudonym for vehicle Vb; Step S206: Vehicle Va receives responses from surrounding vehicles and verifies the legitimacy of the responding vehicle identity; if the responding vehicle identity is legitimate, execute step S207; otherwise skip this step; Step S207: Vehicle Va calculates the similarity between itself and the responding vehicle. If the calculated result is consistent with the similarity provided by the responding vehicle, the responding vehicle is a legitimate vehicle; otherwise, the malicious behavior is reported to TA through the RSU; Step S208: Vehicle Va sets a minimum number threshold λ for vehicles participating in the short-term pseudonym replacement. If the number of vehicles s actually participating in the pseudonym replacement exceeds the threshold λ, vehicle Va selects the first λ legal vehicles with the highest driving state similarity to establish a λ-mixing zone; if the number of vehicles s actually participating in the pseudonym replacement does not exceed the threshold λ, each participating vehicle broadcasts to neighboring nodes pseudonym change notifications to establish a k-anonymity mixed zone; The λ-mixing zone and the k-anonymous mixing zone are collectively referred to as mixing zones; Step S209: Vehicle Va generates a group key ka for the vehicle in the mixed zone, and then generates a message Ga based on ka= <PID i ,ka,T Ga >, where PID i is the short-term pseudonym currently used by Va, T Ga is the current timestamp and uses the private key SK Va Sign the message Ga to get SIG(Ga;SK Va ); Step S210: Vehicle Va uses the public key PK of the vehicle in the mixed zone Vchange Encrypt Ga to get the ciphertext C = E (PK Vchange ,Ga), then C and SIG(Ga;SK Va ) are sent to vehicles in the mixed zone respectively; Step S211: V change The vehicle in the game uses its own private key SK Vchange Decrypt the ciphertext C and verify SIG(Ga;SK Va ), and then get ka, then V change The vehicles in the group will build an encrypted communication group with vehicle Va, which is called a hybrid name-changing zone.

5. The pseudonym replacement method based on vehicle similarity for Internet of Vehicles according to claim 1, characterized in that: The step S3 comprises the following steps: Step S301: During the validity period of the mixed name change zone, multiple vehicles simultaneously apply for a new round of pseudonym changes and adjust the driving speed and trajectory; The validity period of the mixed name change zone means that when the number of pseudonyms used by a vehicle exceeds a set critical value, the system will send a signal indicating that the vehicle should go through a new round of short-term pseudonym application process; Step S301: The vehicle encrypts the pseudonym using the established session key ka and sends the changed pseudonym to other vehicles; Step S302: Fog layer R TA Update the mapping relationship between long-term pseudonyms and the latest round of short-term pseudonyms.

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