Method for protecting privacy of dynamic grouping messages in internet of vehicles based on inner product predicate encryption

Abstract

The application provides a vehicle networking dynamic grouping message privacy protection method based on inner product predicate encryption, and belongs to the technical field of vehicle networking security. The application solves the technical problems of uncontrollable broadcast message receiving range between vehicle members of vehicle networking dynamic grouping, easy leakage of vehicle type information, and insufficient security of key management under the condition of high dynamic change of vehicles. The application comprises the following steps: S1, system initialization; S2, roadside unit and vehicle realize bidirectional identity authentication and obtain the group member type of the vehicle; S3, the roadside unit generates a group key for the vehicle members in the group in the domain; S4, the roadside unit dynamically updates the group key of the vehicle members in the group in the domain; S5, the vehicle in the group realizes privacy protection and reliable transmission of the group broadcast message based on signature and group key encryption technology; and the application realizes that the message is broadcasted only among the vehicles in the same type group without exposing the real identity and type information of the vehicle.

Description

Technical Field

[0001] This invention relates to the field of vehicle network security technology, and in particular to a method for protecting the privacy of dynamic packet messages in vehicle networks based on inner product predicate encryption. Background Technology

[0002] With the rapid development of intelligent transportation systems and wireless communication technologies, the Internet of Vehicles (IoV) provides crucial technological support for road safety, improved traffic efficiency, and autonomous driving and intelligent collaborative applications through collaborative communication between vehicles (V2V) and roadside units (V2I). During IoV operation, vehicle status information, traffic event information, and collaborative control commands need to be efficiently distributed across the network via broadcast or quasi-broadcast methods, which places higher demands on the security and privacy protection capabilities of the communication mechanisms.

[0003] However, the Internet of Vehicles (IoV) communication environment is characterized by high openness, large node scale, and susceptibility to eavesdropping on wireless channels. Attackers can infer vehicle identity characteristics, operating status, and even long-term travel trajectories by passively eavesdropping or actively analyzing communication behavior, posing a serious threat to user privacy and system security. To address these issues, existing research primarily focuses on protecting the privacy of the sender's identity, introducing cryptographic techniques such as anonymous authentication and group signatures to hide the vehicle's true identity and achieve unidentifiable message senders. The paper "Enhancing Security and Anonymity in the Internet of Vehicles Using Group Signatures" achieves vehicle anonymity and conditional traceability based on a group signature mechanism and improves authentication efficiency in broadcast scenarios through batch verification technology. The paper "Anonymous authentication based on blockchain and zero-knowledge proof for vehicular networks" combines blockchain and zero-knowledge proof technology to achieve vehicle legitimacy verification and identity privacy protection while weakening the assumption of a trusted third party, enhancing the decentralized trustworthiness of the system. Although these solutions have achieved some success in protecting the anonymity of message senders, their communication models generally employ network-wide or large-scale broadcasting, lacking fine-grained control over message recipients. In practical vehicle-to-everything (V2X) applications, vehicle broadcast messages typically have explicit business semantics and reception scope constraints, such as requiring information sharing only among vehicles of the same type. Broadcasting such messages indiscriminately to all vehicles would not only significantly increase communication load and verification overhead but could also lead to sensitive information being obtained by non-target vehicles, thus introducing new privacy risks. Therefore, how to effectively constrain message recipients while ensuring the anonymity of the sender has become a pressing issue in V2X privacy protection research.

[0004] To limit message propagation and implement access control, some studies have introduced packet communication and group key management mechanisms, enabling only vehicles holding legitimate group keys to decrypt and receive broadcast messages. However, in the vehicle-to-everything (V2X) environment, vehicles move at high speeds, the topology changes dynamically, and vehicles frequently switch between different roadside unit coverage areas, causing communication group membership relationships to continuously change over time. Under these conditions, if the packet communication mechanism lacks efficient member management and key update strategies, it can easily lead to frequent group key updates, excessive communication overhead, and even security vulnerabilities such as vehicles that have left the group still being able to access subsequent communication content. While existing research has alleviated these problems to some extent, it still has significant limitations. For example, the paper "Secure message communication protocol among vehicles in smart city" designs a communication protocol based on elliptic curve cryptography and hash functions, which has low computational and communication overhead, but relies on trusted cluster head vehicles and does not consider the dynamic group key update problem. The paper "A robust and efficient password-based conditional privacy preserving authentication and group-key agreement protocol for VANETs" proposes a password-based group key generation mechanism, whose key update process relies on a trusted central authority (TA) remaining online and requires distributing new keys to vehicles within the group via unicast, limiting scalability and efficiency. The paper "Secure many-to-many authentication and key agreement scheme for vehicular networks" implements secure authentication and key negotiation between vehicles and roadside units, but the scheme relies on bilinear pairing operations and needs to broadcast a large number of vehicle public keys during the key update phase, resulting in high computational and communication overhead. Furthermore, most existing schemes rely on pre-configured offline authentication keys. In application scenarios with limited vehicle resources, offline storage of a large number of keys not only increases the system burden but may also introduce additional security risks in scenarios involving new user additions or key leaks. Therefore, under the premise of ensuring vehicle identity privacy and the non-linkability of message senders, how to achieve restricted broadcasting based on vehicle type, and how to maintain communication groups securely, efficiently and scalably in a dynamic environment where vehicles frequently join and leave, remains a key challenge in protecting the privacy of connected vehicle messages. Summary of the Invention

[0005] This invention provides a privacy protection method for dynamic packet messages in vehicle-to-everything (V2X) networks based on inner product predicate encryption. It solves the technical problems in existing V2X networks, such as the difficulty in precisely controlling the reception range of broadcast messages, the easy leakage of vehicle type information during communication, and the insufficient security of packet communication and key management under highly dynamic vehicle conditions. This invention achieves vehicle type identification and packet communication without exposing the true identity and type of vehicles in plaintext, ensuring that messages are only propagated between vehicles of the same type. It also effectively adapts to the dynamic network environment of frequent vehicle joining and leaving, improving the security and reliability of V2X message communication and exhibiting good applicability and scalability.

[0006] For ease of understanding, the symbols and their meanings involved in this invention are first given in Table 1 below:

[0007] Table 1. Symbols and their meanings

[0008]

[0009] This invention is achieved through the following measures: a method for protecting the privacy of dynamic packet messages in the Internet of Vehicles based on inner product predicate encryption, comprising the following steps:

[0010] S1, System initialization;

[0011] S2. The roadside unit (RSU) performs two-way identity authentication with the vehicle and obtains the vehicle's group member type;

[0012] S3, Roadside Unit (RSU) generates group keys for vehicle members within the group in this domain;

[0013] S4. The Roadside Unit (RSU) dynamically updates the group key for vehicle members within the group in this domain.

[0014] S5. Within the group, vehicles use signature and group key encryption technology to ensure privacy protection and reliable transmission of broadcast messages within the group.

[0015] Further, step S1 includes:

[0016] S11. Trusted Center (TA) initializes system parameters;

[0017] S111, Trusted Center (TA) uses security parameters As input, a cyclic group G of prime order q is chosen, with generator P. Five secure hash functions are also defined. ;

[0018] S112, Trust Center TA from integer multiplication group modulo q Randomly select an element As the system master key And calculate the system public key. ;

[0019] S113, The Trusted Center (TA) executes the initialization algorithm of the inner product predicate encryption system. Generate inner product predicate encryption parameters and inner product predicate encryption master key ,in The dimension of the predicate vector;

[0020] S114, TA publishes system public parameters and securely store the system master key. and inner product predicate encryption master key This is used for subsequent key generation and management between vehicles and roadside units (RSUs).

[0021] S12, Real identity is Vehicle type is vehicles Before joining the vehicle networking system, you need to register with TA to obtain the credentials and keys required for subsequent authentication and communication.

[0022] S121, Trusted Center (TA) first serves the vehicle. Generate kana identifiers to replace real identity Participate in system interaction. Subsequently, the Trusted Analyst (TA) constructs attribute vectors. The vector dimension is consistent with the attribute space in the inner product predicate encryption system. The Trusted Center (TA) executes the inner product predicate encryption algorithm. Generate vehicle type certificate This is used to bind vehicle pseudonyms to vehicle type information;

[0023] S122, Trusted Center (TA) from Select random numbers and calculate , , and will As a vehicle private key , As a vehicle public key ;

[0024] S123, Trusted Center (TA) identifies pseudonyms via a secure channel. Vehicle type certificate and public / private key pairs Send to vehicle .vehicle Upon receipt, the above information is securely stored in the on-board unit (OBU) for use in subsequent identity authentication and message sending stages;

[0025] S13, Real identity is roadside units Before joining the vehicle networking system, you need to register with TA to obtain the key materials required for vehicle identity authentication and type identification.

[0026] S131, Trusted Center (TA) from Select random numbers and calculate , , .in, As private key , As its corresponding public key ;

[0027] S132. Simultaneously, the Trusted Center (TA) executes the key generation algorithm of the inner product predicate encryption system. for Generate type certificate decryption key The predicate vector is defined as follows: , Indicates that TA is Assigned attribute parameters. Type credential decryption key. Used only in the identity authentication phase for vehicle type credentials. Decryption is performed to obtain vehicle type information;

[0028] S133, The Trusted Center (TA) transmits the type credential decryption key via a secure channel. and public / private key pairs Send to roadside unit This is to support the vehicle authentication and type identification functions performed during system operation.

[0029] Further, step S2 includes:

[0030] S21, Roadside Unit Periodically from Select random numbers and calculate Subsequently, the roadside unit Construct message ,in This is the current timestamp, used to prevent replay attacks. Generate signature and broadcast authentication messages within its communication coverage area. ;

[0031] S22, Vehicles Received authentication message Then, first based on the timestamp Verify the timeliness of the message. If the verification passes, the vehicle... calculate If the equation If established, then the vehicle Confirm roadside unit It is a legal roadside unit; otherwise, the vehicle Termination and roadside unit communication;

[0032] The correctness of the above verification equation can be derived as follows:

[0033]

[0034] S23, After completing the roadside unit After the legality is verified, the vehicle from Select random numbers and calculate Vehicle configuration information ,in Use the current timestamp and generate a signature. Subsequently, the vehicle proceeded via the public access road to the roadside unit. Send authentication message ;

[0035] S24, Roadside Unit Received authentication message Then, first based on the timestamp Verify its timeliness. If the verification passes, the roadside unit... calculate If the equation If established, then the roadside unit Confirm vehicle The vehicle must be legitimate; otherwise, further communication will be terminated.

[0036] The correctness of the above verification equation can also be derived as follows:

[0037]

[0038] S25. After completing vehicle identification authentication, the roadside unit Decrypt the key using type credentials Execution inner product predicate decryption algorithm From vehicle type certificate Vehicles in China are being restored. Type information;

[0039] S26, subsequently, roadside units Within the system's set buffer time The system collects authentication requests from other vehicles and repeats the authentication and type recovery process described above. Roadside Unit Legal vehicles of the same vehicle type are grouped into the same communication group, denoted as [group name missing]. This provides support for subsequent group key generation and secure communication within the group.

[0040] Further, step S3 includes:

[0041] S31. After completing identity authentication and determining the communication group Afterwards, for all legal vehicles within the group Roadside unit from Random selection and calculate Subsequently, the roadside unit For vehicles calculate and the corresponding Stored in a local database for further calculations. ;

[0042] S32. Based on this, roadside units Generate a with Random numbers with consistent value space and from Select random numbers As a group key Based on this, RSU constructs the following (n+1)th degree polynomial:

[0043]

[0044] Where n represents the communication group The number of legal vehicles in the country;

[0045] S33, Roadside Unit Calculate message authentication code ,in This is the current timestamp. Subsequently, the roadside unit... Broadcast response message to vehicles in the group ;

[0046] S34, Vehicles Received from roadside unit response message Next, verify the timestamp. The validity of the message is checked. If the verification fails, the message is discarded; otherwise, the vehicle... calculate , and will Substitution Thus recovering the group key ;

[0047] The above The correctness of the calculation can be derived from the following derivation:

[0048]

[0049] S35. To verify the integrity and legitimacy of the group key distribution message, the vehicle... Calculate message authentication code And determine whether it satisfies If the equation is true, then the verification is successful. Accept and save the group key This is used for subsequent secure communication within the group.

[0050] Further, step S4 includes:

[0051] S41. The Roadside Unit (RSU) actively updates the group key according to a predefined time period.

[0052] S411, Roadside Unit Maintain a key validity period for each communication group. When the current timestamp satisfy ,in Indicates the time of the last group key generation or update, roadside unit Actively trigger the group key update process;

[0053] S412, Roadside Unit Based on the current group key and timestamp A new group key is derived through a one-way hash function. Subsequently, the roadside unit from Select random numbers and calculate Roadside unit Construct update message And generate a signature .at last, Using group keys Update message ,sign Perform encryption to generate encrypted update messages and encrypt the update message Broadcast to all authorized vehicles in the group;

[0054] S413, vehicles within the group receive encrypted update messages. Then, first use the group key. Decrypt it to obtain the update message With signature And verify the timestamp The novelty. If the verification passes, the vehicle calculation... If the equation If the request is successful, the vehicle confirms that the update message was generated by a legitimate Roadside Unit (RSU), and then calculates and updates the group key locally. and securely delete the group key. ;

[0055] The correctness of the above verification equation can be derived as follows:

[0056]

[0057] S42. When a new vehicle joins the communication group managed by the current Roadside Unit (RSU), the RSU updates the group key based on a one-way hash function.

[0058] S421, When the vehicle via roadside unit After identity verification and being determined as a legitimate member, the roadside unit Add it to the communication group corresponding to the vehicle type. ;

[0059] S422, Roadside Unit Based on the current group key and timestamp A new group key is derived through a one-way hash function. Subsequently, the roadside unit from Select random numbers and calculate . Construct update message And generate a signature .at last, Using group keys Update message ,sign Perform encryption to generate encrypted update messages and encrypt the update message Broadcast to all authorized vehicles in the group;

[0060] S423, vehicles within the group receive encrypted update messages. Then, first use the group key. Decrypt it to obtain the update message With signature And verify the timestamp The novelty. If the verification passes, the vehicle calculation... If the equation If the request is successful, the vehicle confirms that the update message was generated by a legitimate Roadside Unit (RSU), and then calculates and updates the group key locally. and securely delete the group key. ;

[0061] S43. When a vehicle actively leaves the communication area or is identified as a malicious node, the Roadside Unit (RSU) updates the group key based on polynomial reconstruction.

[0062] S431, When the vehicle Leave the roadside unit When the communication coverage area is breached, or when a node is identified as an illegal node due to detected abnormal behavior, the roadside unit... Immediately delete it from the group member list and local database;

[0063] S432, Roadside Unit Delete from database Then a new group key is randomly selected. And generate a new salinity. Based on the remaining n-1 legal vehicles, the roadside unit Reconstruct the group key distribution polynomial:

[0064]

[0065] S433, subsequently, roadside units from Select random numbers And calculate Roadside unit Construct update message and generate a signature. Finally, the roadside unit Using group keys Update message ,sign Encryption is performed, and an encrypted update message is generated. It also broadcasts encrypted update messages to the remaining vehicles in the group. .

[0066] S434. Legitimate vehicles within the group receive encrypted update messages. Then, first use the group key. Decrypt it to obtain the update message With signature And verify the timestamp The freshness. Then calculate... If the equation Establishment, vehicle utilization Distribute polynomials via group key Calculate group key Thus obtaining the group key .

[0067] S435, Regarding vehicles Although it may obtain the group key distribution polynomial However, due to the lack of valid parameters , Therefore, the group key cannot be recovered. This ensures that vehicles leaving the group cannot access subsequent group communication content.

[0068] Further, step S5 includes:

[0069] S51, Assumption Vehicles in Message m needs to be broadcast to other vehicles in the group. from Select random numbers and calculate , , Subsequently, Construct message and generate a signature. ;

[0070] S52, Using group keys Regarding the message ,sign and current timestamp Perform symmetric encryption to obtain encrypted broadcast messages. ;

[0071] S53, when Or other vehicles in the group receive encrypted broadcast messages. Then, first use the group key. Decrypt it and based on the timestamp Verify the timeliness of the message. If verification fails, discard the message.

[0072] S54. After passing the time validity verification, the receiver signs the message. Perform a validity check to determine whether the following equation is true:

[0073]

[0074] If the equation is true, it indicates that the message was generated by a legitimate vehicle within the group and has not been tampered with during transmission, and the receiver accepts message m; otherwise, the message is discarded.

[0075] The correctness of the above verification equation can be derived as follows:

[0076]

[0077] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0078] (1) By introducing vehicle type as a message propagation constraint, this invention enables broadcast messages to be distributed only among vehicles of the same type, effectively avoiding the information redundancy and privacy leakage risks caused by indiscriminate message broadcasting in existing vehicle networks, and improving the targeting and security of message transmission.

[0079] (2) The present invention adopts a vehicle identity-type credential mechanism based on inner product predicate encryption. During identity authentication and communication, there is no need to expose vehicle type information in plaintext. The type is determined only by legitimate roadside units, thereby reducing the probability of leakage of vehicle type information during network transmission and node interaction and enhancing the system's ability to protect type privacy.

[0080] (3) This invention combines dynamic factors such as vehicle joining, leaving and time cycle changes to securely update the group key of the communication group, ensuring that vehicles leaving the group cannot continue to obtain subsequent group communication content. It can effectively adapt to the characteristics of high-speed vehicle movement and frequent topology changes in the vehicle network environment, and improve the security and reliability of the system.

[0081] (4) By introducing random numbers and timestamps into the intra-group broadcast communication process and combining them with the group key to sign and encrypt messages, this invention ensures that multiple messages sent by the same vehicle at different times are independent of each other in terms of communication characteristics, and external eavesdroppers cannot effectively associate them based on message content, encryption form or signature information. Attached Figure Description

[0082] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0083] Figure 1 The present invention provides an overall flowchart of a method for protecting the privacy of dynamic packet messages in the Internet of Vehicles based on inner product predicate encryption.

[0084] Figure 2 This is a diagram of the vehicle networking system architecture model in this invention.

[0085] Figure 3 The flowchart of a two-way authentication method for a vehicle-to-everything (V2X) dynamic packet message privacy protection method based on inner product predicate encryption provided by the present invention.

[0086] Figure 4This invention provides a flowchart of group key generation for a method for protecting privacy of dynamic group messages in vehicle networks based on inner product predicate encryption.

[0087] Figure 5 The flowchart illustrates the intra-group encrypted vehicle communication in a vehicle-to-everything (V2X) dynamic group message privacy protection method based on inner product predicate encryption, as provided by this invention. Detailed Implementation

[0088] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. Of course, the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0089] Example 1:

[0090] This embodiment 1 provides a method for protecting the privacy of dynamic packet messages in vehicle-to-everything (V2X) networks based on inner product predicate encryption, such as... Figure 1 As shown, it includes the following steps:

[0091] S1, System initialization;

[0092] S2. The roadside unit (RSU) performs two-way identity authentication with the vehicle and obtains the vehicle's group member type;

[0093] S3, Roadside Unit (RSU) generates group keys for vehicle members within the group in this domain;

[0094] S4. The Roadside Unit (RSU) dynamically updates the group key for vehicle members within the group in this domain.

[0095] S5. Within the group, vehicles use signature and group key encryption technology to ensure privacy protection and reliable transmission of broadcast messages within the group.

[0096] like Figure 2 As shown, the vehicle-to-everything (V2X) system architecture in the privacy protection method for dynamic packet messages based on inner product predicate encryption consists of three entities: Trusted Center (TA), Roadside Unit (RSU), and Onboard Unit (OBU). The functions of each entity are as follows:

[0097] (1) Trusted Center (TA): It is the only authoritative institution in the system that all nodes can trust unconditionally. It is responsible for managing and supervising all nodes in the system, distributing public and private keys to nodes, and generating vehicle type credentials for vehicles that can only be decrypted and verified by the Roadside Unit (RSU).

[0098] (2) Roadside Unit (RSU): Distributed on both sides of the road, it serves as a fixed communication node in the Internet of Vehicles (IoV), responsible for verifying the identity and type of vehicles, generating group keys for vehicles of the same type, and acting as a relay node to provide communication connection between vehicles and the Trusted Center.

[0099] (3) On-board Unit (OBU): Installed inside the vehicle, the vehicle establishes communication with other entities through the OBU. Vehicles of the same type within the same Roadside Unit (RSU) domain form a communication group. Privacy information such as the vehicle's private key, pseudonym, vehicle type and vehicle type certificate, and group key is stored in the tamper-proof module of the OBU.

[0100] like Figure 3 As shown, the specific content of S2 includes the following steps:

[0101] S21, Roadside Unit Periodically from Select random numbers and calculate Subsequently, the roadside unit Construct message ,in This is the current timestamp, used to prevent replay attacks. Generate signature and broadcast authentication messages within its communication coverage area. ;

[0102] S22, Vehicles Received authentication message Then, first based on the timestamp Verify the timeliness of the message. If the verification passes, the vehicle... calculate If the equation If established, then the vehicle Confirm roadside unit It is a legal roadside unit; otherwise, the vehicle Termination and roadside unit communication;

[0103] S23, After completing the roadside unit After the legality is verified, the vehicle from Select random numbers and calculate Vehicle configuration information ,in Use the current timestamp and generate a signature. Subsequently, the vehicle proceeded via the public access road to the roadside unit. Send authentication message ;

[0104] S24, Roadside Unit Received authentication message Then, first based on the timestamp Verify its timeliness. If the verification passes, the roadside unit... calculate If the equation If established, then the roadside unit Confirm vehicle The vehicle must be legitimate; otherwise, further communication will be terminated.

[0105] S25. After completing vehicle identification authentication, the roadside unit Decrypt the key using type credentials Execution inner product predicate decryption algorithm From vehicle type certificate Vehicles in China are being restored. Type information.

[0106] like Figure 4 As shown, the specific content of S3 includes the following steps:

[0107] S31. After completing identity authentication and determining the communication group Afterwards, for all legal vehicles within the group Roadside unit from Random selection and calculate Subsequently, the roadside unit For vehicles calculate and the corresponding Stored in a local database for further calculations. ;

[0108] S32. Based on this, roadside units Generate a with Random numbers with consistent value space and from Select random numbers As a group key Based on this, RSU constructs the following (n+1)th degree polynomial:

[0109]

[0110] Where n represents the communication group The number of legal vehicles in the country;

[0111] S33, Roadside Unit Calculate message authentication code ,in This is the current timestamp. Subsequently, the roadside unit... Broadcast response message to vehicles in the group ;

[0112] S34, Vehicles Received from roadside unit response message Next, verify the timestamp. The validity of the message is checked. If the verification fails, the message is discarded; otherwise, the vehicle... calculate , and will Substitution Thus recovering the group key ;

[0113] S35. To verify the integrity and legitimacy of the group key distribution message, the vehicle... Calculate message authentication code And determine whether it satisfies If the equation is true, then the verification is successful. Accept and save the group key This is used for subsequent secure communication within the group.

[0114] like Figure 5 As shown, the specific content of S5 includes the following steps:

[0115] S51, Assumption Vehicles in Message m needs to be broadcast to other vehicles in the group. from Select random numbers and calculate , , Subsequently, Construct message and generate a signature. ;

[0116] S52, Using group keys Regarding the message ,sign and current timestamp Perform symmetric encryption to obtain encrypted broadcast messages. ;

[0117] S53, when Or other vehicles in the group receive encrypted broadcast messages. Then, first use the group key. Decrypt it and based on the timestamp Verify the timeliness of the message. If verification fails, discard the message.

[0118] S54. After passing the time validity verification, the receiver signs the message. Perform a validity check to determine whether the following equation is true:

[0119]

[0120] If the equation is true, it indicates that the message was generated by a legitimate vehicle within the group and has not been tampered with during transmission, and the receiver accepts message m; otherwise, the message is discarded.

[0121] Example 2:

[0122] To illustrate how the RSU obtains vehicle type information without disclosing the vehicle's complete identity information in Embodiment 1, this embodiment uses the process of a vehicle obtaining an identity type credential and the RSU decrypting and determining the vehicle type as an example to provide an instance of the vehicle type acquisition mechanism based on inner product predicate encryption. The process described in this embodiment corresponds to... Figure 1 The system initialization phase and Figure 3 The type determination part of the two-way authentication process shown here is explained in detail. Figure 2 Under the system architecture shown, how the TA generates identity type credentials for the vehicle and how the RSU determines the vehicle type.

[0123] To provide a clear and intuitive demonstration of the operation of inner product predicate encryption in the vehicle-to-everything (V2X) identity authentication scenario, this embodiment selects a small-scale, computable set of system parameters in this example to clearly illustrate the computational details of each stage. This embodiment fully demonstrates the entire process from system initialization and encoding of vehicle attribute vectors and access policy vectors to inner product determination, decryption, and vehicle type acquisition.

[0124] 1. System Initialization

[0125] Trusted Center TA Execution System Initialization Algorithm :

[0126] (1) Given security parameters The Trust Center (TA) chooses the prime number p=17. bilinear group And define the attribute vector space and the predicate vector space as Let P and They are The generator.

[0127] (2) The Trusted Center (TA) randomly generates the master key vector. and calculate .

[0128] (3) Finally, the Trusted Center (TA) outputs system parameters. Inner product predicate encryption master key .

[0129] 2. Vehicle attribute coding and ciphertext generation

[0130] (1) Vehicle Register as a public transport vehicle. Meanwhile, the Trusted Center (TA) is for vehicles. Randomly generate kana And concatenate the kana with the type as plaintext. .

[0131] (2) Define attribute vectors Trusted Center (TA) randomly selects And calculate: , .

[0132] (3) Next, the credibility center TA calculates for i=1,2,3 respectively. ,get:

[0133]

[0134]

[0135]

[0136] Finally, a vehicle type certificate is generated. .

[0137] 3. Generation of Roadside Unit (RSU) Predicate Vectors and Private Keys

[0138] (1) The Trusted Center (TA) is a roadside unit. Define predicate vectors and randomly select Calculate the inner product .

[0139] (2) Trusted center TA generates roadside units Decrypting the private key using the inner product predicate , ,Right now

[0140] 4. Internal product decryption and vehicle type recovery

[0141] (1) Roadside unit Decrypting the private key using inner product predicates Vehicle type certificate To perform decryption, first calculate Secondly, calculate

[0142] (2) Further, roadside units calculate

[0143] ,

[0144] (3) Final roadside unit Restoring plaintext Thus, to obtain the vehicle The process demonstrates that the Roadside Unit (RSU) can only successfully decrypt and obtain vehicle type information when the vehicle attribute vector and the Roadside Unit (RSU) predicate vector satisfy the inner product condition, while other vehicle attributes remain hidden.

[0145] This embodiment can be intuitively verified that when the vehicle's attribute vector and the access policy set by the roadside unit (RSU) satisfy the condition that the inner product is zero, the RSU can successfully decrypt and obtain the vehicle type; otherwise, decryption fails, thus effectively realizing the secure determination of the vehicle type and verifying the correctness and feasibility of the proposed scheme in actual vehicle network identity authentication scenarios.

[0146] Example 3:

[0147] To further verify the correctness and feasibility of the polynomial-based group key generation and update mechanism proposed in this invention, this section describes, through specific embodiments, the process of the Roadside Unit (RSU) generating group keys for vehicle groups and the group key update process triggered in scenarios of dynamic vehicle entry or exit. This embodiment corresponds to... Figure 1 The paper describes the group key generation and dynamic update phases of group communication. Through instantiated calculations, it analyzes in detail how the Roadside Unit (RSU) and legitimate vehicles recover and update the group key respectively, and proves the consistency of the calculation results between the two parties, thus demonstrating that this mechanism can effectively ensure the security of group communication.

[0148] Consistent with the aforementioned embodiments, in order to facilitate a more intuitive demonstration of the polynomial construction and key recovery process, this invention selects small-scale, computable system parameters in the embodiments and uses fixed random numbers instead of hash function outputs. That is, for the same input, the hash function always returns the same value to avoid interference from complex hash operations on the understanding of the embodiments.

[0149] Assuming in the roadside unit Within the coverage area, vehicles that have completed identity authentication and are of the same type constitute a communication vehicle group. There are currently 3 legal vehicles in this crew, designated as follows: , , Roadside unit As a group management entity, it is responsible for generating group keys for vehicle groups and triggering the corresponding group key update process according to the mechanism designed in this invention when a vehicle joins or leaves.

[0150] 1. Parameter initialization

[0151] (1) The Trusted Center (TA) selects a small-scale elliptic curve additive group G of order 23, with generator denoted as P. Subsequently, the TA randomly selects the system master key. And calculate the system public key.

[0152] (2) TA is a vehicle (Real identity is) Generate kana Choose a random number ,calculate , The output is a fixed random number of 3. Similarly, for vehicles... Choose a random number ,calculate , The output is a fixed random number of 5. For vehicles Choose a random number ,calculate , The output is a fixed random number of 7. .

[0153] 2. Group Key Generation

[0154] like Figure 4 As shown, after completing group construction, the RSU enters the group key generation phase. First, the RSU selects a random group key and constructs a polynomial. Then, it broadcasts the relevant parameters to the vehicles within the group, and each vehicle uses its own valid parameters to recover the group key. A specific example is as follows:

[0155] (1) Roadside unit Select random numbers during the group key generation stage. ,calculate .

[0156] (2) Subsequently calculate

[0157] , , .

[0158] (3) Roadside unit calculate , , Assume that the hash function outputs fixed values ​​of 15, 17, and 19 for inputs of 12P, 10P, and 16P, respectively.

[0159] (4) Then select a random number As a salt value, a random number is also selected as the shared group key. And construct an n+1 degree polynomial.

[0160]

[0161] Finally, the RSU broadcast to the crew. and polynomials .

[0162] (5) Vehicles calculate , , Similarly, vehicles calculate , , ;vehicle calculate , , For any vehicle in any group, the correct group key can be calculated. .like Figure 5 As shown, vehicles within the group communicate via encrypted broadcast based on the group key. Only vehicles holding the valid group key can successfully decrypt and verify the message, thus enabling restricted secure broadcasting between vehicles of the same type.

[0163] 3. RSU proactive updates and new vehicle additions

[0164] (1) When the new vehicle After identity verification, they joined the crew. Or, when the timestamp meets the predefined update conditions, the roadside unit... The group key update process is initiated proactively. Assume the group key currently used by the train crew is... .

[0165] (2) Roadside unit A new group key is derived using a one-way hash function based on the current group key and timestamp. Assuming the hash function is applied to the input... The output is a fixed value of 22. Roadside unit. The group broadcasts a group key update message to all vehicles in the group, which includes a timestamp. .

[0166] (3) For vehicles within the group, possess the group key. and timestamp Capable of independent calculation Thus, the updated group key is obtained. .

[0167] 4. Vehicle leaves

[0168] (1) When the vehicle When a roadside unit actively leaves the communication domain or is identified as a malicious node, It is necessary to prevent it from continuing to access subsequent group communication content, thus triggering the vehicle leaving the group key update process. Assume the group key currently used by the vehicle group is... .

[0169] (2) Roadside unit Select random number As the new salt value, a random number is selected as the new group key. And reconstruct the nth degree polynomial

[0170]

[0171] Finally, roadside units Broadcast polynomial to train crew .

[0172] (3) Vehicles calculate Similarly, vehicles calculate ;vehicle calculate Therefore, even if a departing vehicle receives an updated message, it cannot calculate the new group key, thus ensuring forward security of group communication.

[0173] This embodiment demonstrates that the proposed group key management mechanism can ensure that legitimate members can correctly recover the group key when vehicles change dynamically, while vehicles that leave or are unauthorized cannot obtain the updated group communication key.

[0174] 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 principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for protecting the privacy of dynamic packet messages in vehicle-to-everything (V2X) networks based on inner product predicate encryption, characterized in that, Includes the following steps: S1, System initialization; S2. The roadside unit (RSU) performs two-way identity authentication with the vehicle and obtains the vehicle's group member type; S3, Roadside Unit (RSU) generates group keys for vehicle members within the group in this domain; S4. The Roadside Unit (RSU) dynamically updates the group key for vehicle members within the group in this domain. S5. Within the group, vehicles use signature and group key encryption technology to ensure privacy protection and reliable transmission of broadcast messages within the group.

2. The method for protecting the privacy of dynamic packet messages in vehicle-to-everything (V2X) networks based on inner product predicate encryption according to claim 1, characterized in that, S1 includes the following steps: S11. Trusted Center (TA) initializes system parameters; S12, Vehicles Before joining the vehicle network system, complete the registration with the Trusted Center (TA) to obtain the credentials and keys required for subsequent authentication and communication. S13. Before joining the vehicle-to-everything (V2X) system, the Roadside Unit (RSU) registers with the Trusted Center (TA) to obtain the key materials required for vehicle identity authentication and type identification.

3. The method for protecting the privacy of dynamic packet messages in vehicle-to-everything (V2X) networks based on inner product predicate encryption according to claim 1, characterized in that, In step S11, the Trusted Center (TA) initializes system parameters, including the following steps: S111, Trusted Center (TA) uses security parameters As input, a cyclic group G of prime order q is chosen, with generator P, and five secure hash functions are defined. ; S112, Trust Center TA from integer multiplication group modulo q Randomly select an element As the system master key And calculate the system public key. ; S113, The Trusted Center (TA) executes the initialization algorithm of the inner product predicate encryption system. Generate inner product predicate encryption parameters and inner product predicate encryption master key ,in The dimension of the predicate vector; S114, Trusted Center (TA) publishes system public parameters. and securely store the system master key. and inner product predicate encryption master key It is used for the generation and management of keys for subsequent vehicles and roadside units (RSUs).

4. The method for protecting the privacy of dynamic packet messages in vehicle-to-everything (V2X) networks based on inner product predicate encryption according to claim 1, characterized in that, In S12, the true identity is Vehicle type is vehicles Before joining the connected vehicle system, complete the registration with the Trusted Center (TA) to obtain the credentials and keys required for subsequent authentication and communication, including the following steps: S121, Trusted Center (TA) first serves the vehicle. Generate kana identifiers to replace real identity In participating in system interaction, the Trusted Center (TA) constructs attribute vectors. The vector dimension is consistent with the attribute space in the inner product predicate encryption system, and the Trusted Center (TA) executes the inner product predicate encryption algorithm. Generate vehicle type certificate This is used to bind vehicle pseudonyms to vehicle type information; S122, Trusted Center (TA) from Select random numbers and calculate , , and will As private key , As public key ; S123, Trusted Center (TA) identifies pseudonyms via a secure channel. Vehicle type certificate and public / private key pairs Send to vehicle ,vehicle Upon receipt, the aforementioned information is securely stored in the on-board unit (OBU) for use in subsequent identity authentication and message sending phases.

5. The method for protecting the privacy of dynamic packet messages in vehicle-to-everything (V2X) networks based on inner product predicate encryption according to claim 1, characterized in that, In S13, the true identity is roadside units Before joining the vehicle-to-everything (V2X) system, complete registration with the Trusted Center (TA) to obtain the key materials required for vehicle identity authentication and type identification, including the following steps: S131, Trusted Center (TA) from Select random numbers and calculate , , ,in, As a roadside unit private key , As its corresponding public key ; S132, The Trusted Center (TA) executes the key generation algorithm of the inner product predicate encryption system. for Generate type certificate decryption key Wherein, the predicate vector is defined as , Indicates that TA is Assigned attribute parameters, type credential, decryption key Used in the identity authentication phase for vehicle type credentials. Decryption is performed to obtain vehicle type information; S133, The Trusted Center (TA) transmits the type credential decryption key via a secure channel. and public / private key pairs Send to roadside unit This is to support the vehicle authentication and type identification functions performed during system operation.

6. The method for protecting the privacy of dynamic packet messages in vehicle-to-everything (V2X) networks based on inner product predicate encryption according to claim 1, characterized in that, Step S2 includes the following steps: S21, Roadside Unit Periodically from Select random numbers and calculate , Construct message ,in This is the current timestamp, used to prevent replay attacks. Generate signature and broadcast authentication messages within its communication coverage area. ; S22, Vehicles Received authentication message Then, first based on the timestamp Verify the timeliness of the message; if the verification passes, the vehicle... calculate If the equation If established, then the vehicle Confirm roadside unit It is a legal roadside unit; otherwise, the vehicle Termination and roadside unit communication; S23, After completing the roadside unit After the legality is verified, the vehicle from Select random numbers and calculate ,vehicle Construct message ,in Use the current timestamp and generate a signature. ,vehicle via public channel to roadside unit Send authentication message ; S24, Roadside Unit Received Then, first based on the timestamp Verify its timeliness; if the verification passes, the roadside unit... calculate If the equation If it is established, then confirm The vehicle must be legitimate; otherwise, further communication will be terminated. S25. After completing vehicle identification authentication, the roadside unit Decrypt the key using type credentials Execution inner product predicate decryption algorithm From vehicle type certificate Vehicles in China are being restored. Type information; S26, Roadside Unit Within the system's set buffer time The roadside unit collects authentication requests from other vehicles and repeats the authentication and type recovery process described above. Legal vehicles of the same vehicle type are grouped into the same communication group, denoted as [group name missing]. .

7. The method for protecting the privacy of dynamic packet messages in vehicle-to-everything (V2X) networks based on inner product predicate encryption according to claim 1, characterized in that, S3 includes the following steps: S31. After completing identity authentication and determining the communication group Afterwards, for all legal vehicles within the group Roadside unit from Select random numbers and calculate Roadside unit For vehicles calculate and the corresponding Stored in a local database, calculation ; S32, Roadside Unit Generate a with Random numbers with consistent value space and from Select random numbers As a group key Based on this, RSU constructs the following (n+1)th degree polynomial: ； Where n represents The number of legal vehicles in the country; S33, Calculate message authentication code ,in This is the current timestamp. Broadcast response message to vehicles in the group ; S34, Received from response message Next, verify the timestamp. The validity of the message is checked; if the verification fails, the message is discarded. Otherwise, calculate , and will Substitution Thus recovering the group key ; S35. To verify the integrity and legitimacy of the group key distribution message, the vehicle... Calculate message authentication code And determine whether it satisfies If the equation holds true, then the verification is successful, and the vehicle... Accept and save the group key This is used for subsequent secure communication within the group.

8. The method for protecting the privacy of dynamic packet messages in vehicle-to-everything (V2X) networks based on inner product predicate encryption according to claim 1, characterized in that, S4 includes the following steps: S41. The Roadside Unit (RSU) actively updates the group key according to a predefined time period. In step S41, the roadside unit (RSU) actively updates the group key according to a predefined time period, including the following steps: S411, Roadside Unit Maintain a key validity period for each communication group. When the current timestamp satisfy ,in Indicates the time of the last group key generation or update, roadside unit Actively trigger the group key update process; S412, Roadside Unit Based on the current group key and timestamp A new group key is derived through a one-way hash function. Roadside unit from Select random numbers and calculate Roadside unit Construct update message And generate a signature , Using group keys Update message ,sign Perform encryption to generate encrypted update messages and encrypt the update message Broadcast to all authorized vehicles in the group; S413, vehicles within the group receive encrypted update messages. Then, first use the group key. Decrypt it to obtain the update message With signature And verify the timestamp The freshness of the vehicle, if verified, will be used for vehicle calculation. If the equation If established, the vehicle confirms that the update message was sent by a legitimate roadside unit. Generate, compute, and update the group key locally. and securely delete the group key. ; S42. When a new vehicle joins the communication group currently managed by the RSU, the roadside unit RSU updates the group key based on a one-way hash function. In step S42, a new vehicle joins the communication group currently managed by the Roadside Unit (RSU). The RSU updates the group key based on a one-way hash function, including the following steps: S421, When the vehicle via roadside unit After identity verification and being determined as a legitimate member, the roadside unit Add it to the communication group corresponding to the vehicle type. ; S422, Roadside Unit Based on the current group key and timestamp A new group key is derived through a one-way hash function. , from Select random numbers and calculate , Construct update message And generate a signature , Using group keys Update message ,sign Perform encryption to generate encrypted update messages and encrypt the update message Broadcast to all authorized vehicles in the group; S423, vehicles within the group receive encrypted update messages. Then, first use the group key. Decrypt it to obtain the update message With signature And verify the timestamp The freshness of the vehicle, if verified, will be used for vehicle calculation. If the equation If established, the vehicle confirms that the update message was sent by a legitimate roadside unit. Generate, then calculate and update the group key locally. and securely delete the group key. ; S43. When a vehicle actively leaves the communication area or is identified as a malicious node, the Roadside Unit (RSU) updates the group key based on polynomial reconstruction.

9. A method for protecting the privacy of dynamic packet messages in vehicle-to-everything (V2X) networks based on inner product predicate encryption as described in claim 1, characterized in that, In step S43, when a vehicle actively leaves the communication area or is identified as a malicious node, the Roadside Unit (RSU) updates the group key based on polynomial reconstruction, including the following steps: S431, When the vehicle Leave the roadside unit When the communication coverage area is breached, or when a node is identified as an illegal node due to detected abnormal behavior, the roadside unit... Immediately delete it from the group member list and local database; S432, Roadside Unit Delete from database Randomly select a new group key And generate a new salinity. Based on the remaining n-1 legal vehicles, Reconstruct the group key distribution polynomial: ； S433, Roadside Unit from Select random numbers And calculate Roadside unit Construct update message and generate a signature. , Using group keys Update message ,sign Encryption is performed, and an encrypted update message is generated. It also broadcasts encrypted update messages to the remaining vehicles in the group. ; S434. Legitimate vehicles within the group receive encrypted update messages. Then, first use the group key. Decrypt it to obtain the update message With signature And verify the timestamp Freshness, calculation If the equation Establishment, vehicle utilization ,pass Calculate group key Thus obtaining the group key ; S435, Regarding Obtain the group key distribution polynomial Due to the lack of valid parameters , Unable to recover This ensures that vehicles leaving the group cannot access subsequent group communication content.

10. A method for protecting the privacy of dynamic packet messages in vehicle-to-everything (V2X) networks based on inner product predicate encryption as described in claim 1, characterized in that, Step S5 includes the following steps: S51, Assuming a communication group Vehicles in Message m needs to be broadcast to other vehicles in the group. from Select random numbers and calculate , , , Construct message and generate a signature. ; S52, Vehicles Using group keys Regarding the message ,sign and current timestamp Perform symmetric encryption to obtain encrypted broadcast messages. ; S53, when Or other vehicles in the group receive encrypted broadcast messages. Then, first use the group key. Decrypt it and based on the timestamp Verify the timeliness of the message; if verification fails, discard the message. S54. After passing the time validity verification, the receiver signs the message. Perform a validity check to determine whether the following equation is true: ； If the equation is true, it indicates that the message was generated by a legitimate vehicle within the group and has not been tampered with during transmission; the receiver accepts m. Otherwise, the message is discarded.

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