A pseudonym changing method based on silent and broadcast cycles in a connected vehicle environment

Abstract

The present invention discloses a pseudonym changing method based on silence and broadcast cycles, which collects previous vehicle trajectory data and obtains a stop point according to latitude and longitude coordinates and time. All vehicles entering the stop point area will cyclically use the pseudonyms in the pseudonym pool of the stop point area, and ensure that the same vehicle will not use the same pseudonym at least twice in a row. The concept of stop points in location service privacy protection is introduced into the selection of pseudonym change scenarios in the Internet of Vehicles environment, so that the pseudonym changing method covers more mixed areas that can confuse attackers. The Mean Shift clustering method is applied to the selection of pseudonym change scenarios in the Internet of Vehicles environment to obtain a stop point area. By executing silence and broadcast cycles in the stop point area, the vehicle changes its pseudonym synchronously in the stop point area and the attacker cannot predict the vehicle's location, while preventing grammatical link attacks and semantic link attacks, protecting the vehicle's location privacy, and ensuring the vehicle's driving safety when the pseudonym is changed by controlling the length of the silence period.

Description

Technical Field

[0001] The present invention belongs to the field of vehicle networking information security technology, relates to a pseudonym changing technology, and in particular to a pseudonym changing method based on silence and broadcast cycles in a vehicle networking environment. Background Art

[0002] With the continuous development of Internet of Vehicles, Vehicle Ad Hoc Network (VANET) has become an indispensable key component of intelligent transportation system. VANET ensures the realization of many functions related to vehicle safety, traffic efficiency and entertainment. However, the location privacy security issues in VANET have also attracted wide attention from governments, enterprises and researchers.

[0003] In VANET, vehicles interact with each other and with infrastructure by combining GPS and wireless communication technology, thus realizing a variety of applications. Security-related applications are usually based on security messages: vehicles periodically send security messages to other nearby communication entities to inform other vehicles or infrastructure of their location, speed, direction, and other information, thereby avoiding congestion and accidents that may occur during driving and improving road safety. Although security messages are of great benefit to road safety and traffic flow optimization, attackers can also use security messages to track vehicles without authorization. Attackers collect these security messages through radio eavesdropping and determine the location of vehicles over time, and use the relationship between vehicles and drivers to infringe on user privacy. For example, attackers can obtain user location information, obtain user life trajectory information, real identity, etc., and dangerous attackers may even threaten the user's personal safety. Therefore, it is crucial to adopt a suitable anonymous authentication mechanism to protect the user's location privacy.

[0004] Current security standards (IEEE 1609.2-2013, ETSI 102941-v1.1.1) use pseudonym change as an anonymous authentication mechanism. As an anonymous authentication mechanism, the pseudonym change method breaks the link of the vehicle location sequence by changing the pseudonym, ensuring that the vehicle will not use the same pseudonym for a long time, so as to confuse attackers and protect the user's location privacy. The pseudonym change method first uses a pseudonym to replace the real identifier of the vehicle to send security messages, so that attackers cannot identify the driver, which can provide a certain level of privacy. Secondly, the pseudonym change method solves the problem that dangerous attackers will link the pseudonym with the real identity of the driver by analyzing the vehicle trajectory by changing the pseudonym regularly. In addition, the pseudonym change method has the advantages of less computational complexity and computational overhead compared to the group signature and the pseudonym and group signature hybrid method. However, the pseudonym change method is still subject to some security threats.

[0005] There are two main threats to the pseudonym changing method. First, the attacker will match the new pseudonym of the vehicle with the old pseudonym according to the different times when the pseudonyms of different vehicles are changed, and perform a grammatical connection attack. Second, the attacker will use the content in the security message to predict the location of the vehicle, thereby matching the new pseudonym of the vehicle with the old pseudonym and performing a semantic link attack. Nowadays, researchers have proposed some pseudonym changing methods. Most of the pseudonym changing methods only prevent grammatical connection attacks or semantic link attacks. Although other methods prevent both of the above attacks, they still have limited applicable scenarios or security issues. Therefore, it is particularly important to use a pseudonym changing method that can prevent both grammatical connection attacks and semantic link attacks, includes more change scenarios, and has higher security. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a pseudonym changing method based on silence and broadcast cycles, which is used to solve the problem that some existing pseudonym changing schemes cannot simultaneously prevent grammatical connection attacks and semantic link attacks, have few change scenarios, and need to improve security.

[0007] The technical solution of the present invention to solve the above problem is as follows: a pseudonym changing method based on silence and broadcast cycles, comprising:

[0008] Step 1: Traffic management personnel collect recent vehicle trajectory data in the area of ​​interest (including at least the latitude and longitude position information of the vehicle at a specific time), and then execute step 2.

[0009] Step 2: Filter all longitude and latitude coordinates that stay at the same location for more than a certain period of time, call such coordinates stay points, and execute step 3.

[0010] Step 3: divide the stay points into two categories according to the date: stay points on weekdays and stay points on holidays. Then classify the stay points of these two categories according to five time periods: 0-7:00, 7:00-10:00, 10:00-16:00, 16:00-19:00, and 19:00-24:00, and execute step 4.

[0011] Step 4: Use the mean shift clustering algorithm (Mean Shift) for the ten different types of stay points, cluster them according to the density of the stay points to obtain clusters, and then execute step 5.

[0012] Step 5, calculate the average value of the distances from all points in each cluster to the center of the cluster, use the circular range with the average value as the radius as the stay range of the cluster, and execute step 6.

[0013] Step 6, calculate the average of the stay point density in all stay ranges as the average density. Filter the stay range according to the average density, and take the stay range with a stay point density greater than p times the average density as the stay point area, and stipulate that the vehicle shall change its pseudonym in this area. If the stay point density in the stay range is less than or equal to p times the average density, the stay range is not selected as the stay point area, and step 7 is executed.

[0014] Step 7: Deploy the stay point area according to the central longitude and latitude coordinates and radius of the cluster corresponding to the stay point area, and execute step 8.

[0015] Step 8: Each RSU applies to the authority (TA) for a pseudonym set based on the number of stay areas within the coverage area of ​​the RSU. The number of pseudonym sets is set based on the number of stay areas within the RSU and the number of vehicles in the stay area during the corresponding period in the collected data, and step 9 is executed.

[0016] Step 9, calculate the broadcasting phase duration of each stop point area according to the average time all vehicles in the stop point area exist in the area and the diameter of the stop point area in the collected data, and execute step 10.

[0017] Step 10: Each stop point area executes a silent and broadcast cycle, which consists of a silent period and a broadcast period. The silent period is set to be less than 2 seconds to ensure the safety of vehicles driving in the stop point area. The broadcast period is set to be the broadcast phase duration calculated in step 9, and step 11 is executed.

[0018] Step 11: Outside the stop area, the vehicle drives using its current pseudonym and executes step 12.

[0019] Step 12: The vehicle enters the stop area. Go to step 13.

[0020] In step 13, the RSU assigns a pseudonym to the vehicle and specifies its lifecycle as the broadcast phase duration calculated in step 9. If the area is in a silent period when the vehicle enters the stop point area, execute step 14, otherwise, execute step 15.

[0021] RSU will always ensure that a vehicle uses a different pseudonym in two consecutive cycles, and all vehicles entering the stop area will cyclically use the pseudonyms in the pseudonym pool of the stop area.

[0022] Step 14: The vehicle is silent and changes the pseudonym assigned by the RSU until the silent period ends, and then executes step 16.

[0023] Step 15: The vehicle continues to drive using its own pseudonym until the next silent period arrives, and then executes step 17.

[0024] Step 16: If the vehicle is still in the stop area, the vehicle uses the pseudonym assigned by the RSU to enter the broadcast period and broadcast its own safety message for the duration of the broadcast phase in the area, and then executes step 17; otherwise, executes step 18.

[0025] Step 17: If the vehicle is still in the stop area, the vehicle enters the silent period, and the RSU assigns another pseudonym to the vehicle, and stipulates that its life cycle is the broadcast phase duration calculated in step 9 of the stop area. The vehicle remains silent until the silent period ends, and step 16 is executed. Otherwise, step 18 is executed.

[0026] Step 18, the vehicle changes to the next pseudonym in its pseudonym pool and continues driving, and executes step 19.

[0027] Step 19: The vehicle resumes normal broadcasting and driving.

[0028] The beneficial effects of the present invention are:

[0029] 1. The present invention combines the concept of stay points in location service privacy protection and applies the Mean Shift clustering method to the selection of pseudonym change scenarios in the Internet of Vehicles environment, so that the pseudonym change covers more mixed areas and protects the vehicle location privacy.

[0030] Second, the present invention utilizes the silence and broadcast cycles in the stop point area to make the vehicles in the area change their pseudonyms synchronously, thus solving the problem of attackers carrying out grammatical link attacks on vehicles.

[0031] 3. The present invention utilizes the silent and broadcasting cycles in the stop point area to change the pseudonyms of vehicles in the area during the silent period, thereby solving the problem of attackers conducting semantic link attacks on vehicles and ensuring the safety of vehicles traveling in the stop point area. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 The figure is a flow chart of the pseudonym changing method based on silent and broadcast cycles in the Internet of Vehicles environment of the present invention.

[0033] Figure 2 The figure is a specific flow chart of the pseudonym changing method based on silent and broadcast cycles in the Internet of Vehicles environment of the present invention. DETAILED DESCRIPTION

[0034] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0035] The technical solution adopted by the present invention is a pseudonym changing method based on silence and broadcast cycles, comprising:

[0036] Step 1: Traffic management personnel collect recent vehicle trajectory data in the area of ​​interest (including at least the latitude and longitude position information of the vehicle at a specific time), and then execute step 2.

[0037] Step 2: Filter all longitude and latitude coordinates that stay at the same location for more than a certain period of time, call such coordinates stay points, and execute step 3.

[0038] Step 3: divide the stay points into two categories according to the date: stay points on weekdays and stay points on holidays. Then classify the stay points of these two categories according to five time periods: 0-7:00, 7:00-10:00, 10:00-16:00, 16:00-19:00, and 19:00-24:00, and execute step 4.

[0039] Step 4: Use the mean shift clustering algorithm (Mean Shift) for the ten different types of stay points, cluster them according to the density of the stay points to obtain clusters, and then execute step 5.

[0040] Step 5, calculate the average value of the distances from all points in each cluster to the center of the cluster, use the circular range with the average value as the radius as the stay range of the cluster, and execute step 6.

[0041] Step 6, calculate the average of the stay point density in all stay ranges as the average density. Filter the stay range according to the average density, and take the stay range with a stay point density greater than p times the average density as the stay point area, and stipulate that the vehicle shall change its pseudonym in this area. If the stay point density in the stay range is less than or equal to p times the average density, the stay range is not selected as the stay point area, and step 7 is executed.

[0042] Step 7: Deploy the stay point area according to the central longitude and latitude coordinates and radius of the cluster corresponding to the stay point area, and execute step 8.

[0043] Step 8: Each RSU applies to the authority (TA) for a pseudonym set based on the number of stay areas within the coverage area of ​​the RSU. The number of pseudonym sets is set based on the number of stay areas within the RSU and the number of vehicles in the stay area during the corresponding period in the collected data, and step 9 is executed.

[0044] Step 9, calculate the broadcasting phase duration of each stop point area according to the average time all vehicles in the stop point area exist in the area and the diameter of the stop point area in the collected data, and execute step 10.

[0045] Step 10: Each stop point area executes a silent and broadcast cycle, which consists of a silent period and a broadcast period. The silent period is set to be less than 2 seconds to ensure the safety of vehicles driving in the stop point area. The broadcast period is set to be the broadcast phase duration calculated in step 9, and step 11 is executed.

[0046] Step 11: Outside the stop area, the vehicle drives using its current pseudonym and executes step 12.

[0047] Step 12: The vehicle enters the stop area. Go to step 13.

[0048] In step 13, the RSU assigns a pseudonym to the vehicle and specifies its lifecycle as the broadcast phase duration calculated in step 9. If the area is in a silent period when the vehicle enters the stop point area, execute step 14, otherwise, execute step 15.

[0049] RSU will always ensure that a vehicle uses a different pseudonym in two consecutive cycles, and all vehicles entering the stop area will cyclically use the pseudonyms in the pseudonym pool of the stop area.

[0050] Step 14: The vehicle is silent and changes the pseudonym assigned by the RSU until the silent period ends, and then executes step 16.

[0051] Step 15: The vehicle continues to drive using its own pseudonym until the next silent period arrives, and then executes step 17.

[0052] Step 16: If the vehicle is still in the stop area, the vehicle uses the pseudonym assigned by the RSU to enter the broadcast period and broadcast its own safety message for the duration of the broadcast phase in the area, and then executes step 17; otherwise, executes step 18.

[0053] Step 17: If the vehicle is still in the stop area, the vehicle enters the silent period, and the RSU assigns another pseudonym to the vehicle, and stipulates that its life cycle is the broadcast phase duration calculated in step 9 of the stop area. The vehicle remains silent until the silent period ends, and step 16 is executed. Otherwise, step 18 is executed.

[0054] Step 18, the vehicle changes to the next pseudonym in its pseudonym pool and continues driving, and executes step 19.

[0055] Step 19: The vehicle resumes normal broadcasting and driving.

[0056] The present invention combines the concept of stay points in location service privacy protection and applies the Mean Shift clustering method to the selection of pseudonym change scenarios in the Internet of Vehicles environment, so that the pseudonym change covers more mixed areas and protects the location privacy of vehicles. The present invention utilizes the silent and broadcast cycles in the stay point area to allow vehicles in the area to change pseudonyms synchronously, solving the problem of attackers performing semantic link attacks on vehicles. The present invention utilizes the silent and broadcast cycles in the stay point area to allow vehicles in the area to change pseudonyms during the silent period, solving the problem of attackers performing semantic link attacks on vehicles, while ensuring the safety of vehicles traveling in the stay point area.

Claims

1. A pseudonym changing method based on silent and broadcast cycles in a vehicle networking environment, characterized in that: include: Step 1, collect previous vehicle trajectory data to obtain the stop points, and then execute step 2; Step 2: Use Mean Shift clustering method to obtain the stay point area based on the stay point density, and then execute step 3; Step 3: All vehicles entering the stop area will cyclically use the pseudonyms in the pseudonym pool of the stop area and execute step 4; Step 4, each stop point area executes corresponding silence and broadcast cycles; The silent and broadcast cycles performed in steps 3 and 4 in the stop point area include: Step 13, each RSU applies to the authority TA for a pseudonym set according to the number of stay point areas within the coverage of the RSU; the number of pseudonym sets is set according to the number of stay point areas in the RSU and the number of vehicles in the stay point areas in the corresponding time period in the collected data, and step 14 is executed; Step 14, calculating the broadcasting phase duration of each stop point area according to the average time all vehicles in the stop point area exist in the area and the diameter of the stop point area in the collected data, and executing step 15; Step 15, each stop point area stipulates that the silent period is less than 2 seconds to ensure the safety of vehicles driving in the stop point area; the broadcast period is stipulated to be the broadcast phase duration calculated in step 14, and step 16 is executed; Step 16, each stop point area performs a silent and broadcast cycle, and then executes step 17; Step 17, if the vehicle enters the area when the area is in a silent period, the vehicle will be silent and execute step 18, otherwise, the area is currently in a broadcast period, execute step 21; Step 18: The vehicle is currently in a silent period. The RSU will assign a pseudonym to the vehicle and indicate that the corresponding life cycle is the broadcast phase duration calculated in step 14 until the silent period ends, and then execute step 20; Step 19: The vehicle still uses its own pseudonym until the broadcast cycle ends, and then executes step 21; When a vehicle enters a stop area, even if the area is currently in the broadcast period, the vehicle will first use its current pseudonym until the silent period arrives, and participate in the synchronous pseudonym change of all vehicles in the area to prevent grammatical connection attacks; All vehicles in the area will receive a pseudonym different from the last RSU during the silent period. The pseudonyms in the RSU pseudonym pool are changed regularly, and each stop area in the RSU will use the pseudonyms in the pseudonym pool cyclically, reducing the cost of generating pseudonyms. Step 20: If the vehicle is still in the stop area, the vehicle enters the broadcast period and starts broadcasting its own safety message for the duration of the broadcast phase in the area, and then executes step 21; otherwise, executes step 22; Step 21, if the vehicle is still in the stop area at this time, the RSU will assign another pseudonym to the vehicle and indicate that the corresponding life cycle is the broadcast phase duration calculated in step 14, and the vehicle remains silent until the silent period ends, and executes step 17, otherwise, executes step 22; All vehicles in the stop area will experience a silence period of less than 2 seconds each time they change their pseudonyms, making it impossible for the enemy to predict the location of the vehicle's next pseudonym based on the content of the security message, thus preventing semantic link attacks. Step 22, the vehicle changes to the next pseudonym in its pseudonym pool and continues driving and broadcasts its safety message normally.

2. According to claim 1, a pseudonym changing method based on silent and broadcast cycles in a vehicle networking environment is characterized in that: In steps 1 and 2, the concept of stay points in location service privacy protection is applied to the selection of pseudonym change areas in the Internet of Vehicles environment, the previous vehicle trajectory data is screened to obtain stay points, and the Mean Shift clustering method is applied to the selection of vehicle pseudonym change scenarios in the Internet of Vehicles environment to obtain appropriate stay point areas, including: Step 5, the traffic management personnel collects recent vehicle trajectory data in the area of ​​interest and executes step 6; Step 6, filter all the longitude and latitude coordinates that stay at the same location for more than a certain period of time, call such coordinates stay points, and execute step 7; The concept of stay points in location service privacy protection is applied to the selection of pseudonym change areas in the Internet of Vehicles environment, covering more mixed areas as places for pseudonym change; at the same time, the silent operation of the mixed areas selected based on the starting point, end point, and points where the vehicle stays for a period of time during the journey protects the semantics of the vehicle trajectory to a certain extent; Step 7, divide the stay points into two categories according to different dates: weekday stay points and holiday stay points; execute step 8; Step 8, classify the above classified stay points according to five time periods: 0-7:00, 7:00-10:00, 10:00-16:00, 16:00-19:00, and 19:00-24:00, and execute step 9; Step 9, using the mean shift clustering algorithm to cluster the different types of stay points based on the density of the stay points to obtain cluster clusters, and then executing step 10; Step 10, according to the clustering results, find the average value of the distances from all points in each cluster to the center of the cluster, take the circular range made with the value as the radius as the stay range of the cluster, and execute step 11; Step 11, calculate the average value of the stay point density in all stay ranges as the average density; select the stay range according to the average density, and take the stay range with a stay point density greater than p times the average density as the stay point area, and stipulate that the vehicle shall change its pseudonym in this area; if the stay point density in the stay range is less than or equal to p times the average density, then the stay range is not selected as the stay point area, and step 12 is executed; Step 12: deploy the stay point area according to the central longitude and latitude coordinates and radius of the cluster corresponding to the stay point area.

3. According to claim 2, a pseudonym changing method based on silent and broadcast cycles in a vehicle networking environment is characterized in that: The vehicle trajectory data in step 5 at least includes the latitude and longitude position information corresponding to the vehicle at a specific time.

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