Cross-border data flow authority control system and method based on homomorphic encryption and block chain technology

Abstract

The invention belongs to the field of data security and cross-border flow control, relates to a cross-border data flow authority control system and method based on homomorphic encryption and a block chain, and aims to solve the problem of accurate control of data flow authority in cross-border informatization service and ensure security, compliance and high efficiency of data cross-border transmission. The system is composed of a homomorphic encryption module, a data transmission module, a data verification module and a block chain authority management module, wherein the homomorphic encryption module generates and issues a public key, and each node encrypts data after obtaining the public key; the data transmission module calculates and transmits a secret state result by using the homomorphic public key; the data verification module decrypts, compares and sends an instruction; and the block chain permission management module records management node permissions and dynamically adjusts the permissions. According to the method, homomorphic encryption, ABE and block chain technologies are combined, a comprehensive solution is formed, the method is suitable for the fields of e-government affairs, finance, medical treatment and the like, the node access permission can be effectively managed, the data flow correctness is guaranteed, and the transmission efficiency and security are improved.

Description

Technical Field

[0001] This invention relates to the field of data security and cross-border data flow control technology, specifically a cross-border data flow permission control system and method based on homomorphic encryption and blockchain technology. This technology aims to solve the problem of precise control over data flow permissions in cross-border information services, ensuring the security, compliance, and efficiency of data during cross-border transmission. Background Technology

[0002] With the acceleration of globalization, cross-border information services are becoming increasingly frequent, involving the cross-border flow of a large amount of sensitive data, including public privacy information. This data flow must not only meet business needs but also strictly comply with the legal and regulatory requirements of both the data transfer parties, especially placing higher demands on access control of relay nodes and destination nodes. However, current data flow access control technologies face numerous challenges, specifically in the following aspects: Limitations of Traditional Access Control Models: Currently, Role-Based Access Control (RBAC) and Attribute-Based Access Control (ABAC) are two commonly used models in the field of access control. RBAC, by introducing the concept of roles, achieves the management of the three-way relationship between permissions, roles, and subjects. However, in multi-network and multi-cloud service environments, its dynamic authorization capabilities and fine-grained access control are insufficient. While ABAC can express access control policies more flexibly and is suitable for large-scale authorization scenarios and fine-grained access control, it cannot independently ensure the correctness of data flow direction and chain.

[0003] Challenges of Attribute-Based Encryption (ABE): ABE technology, including Key Policy Attribute-Based Encryption (KP-ABE) and Ciphertext Policy Attribute-Based Encryption (CP-ABE), combines cryptography with access control. It encrypts data using access policies defined by the data owner, ensuring that only users with matching attributes can decrypt the data. However, the security of the master key is a core issue in ABE schemes; if the master key is leaked, the security of the entire system is threatened. Furthermore, how to securely distribute and dynamically generate the private key required for decryption is also a key challenge in the practical application of ABE technology.

[0004] The Determinism and Efficiency of Data Flow Chains: Ensuring data is transmitted along predetermined paths and preventing data leakage and unauthorized access is a crucial aspect of data security in cross-border data flows. However, existing technologies struggle to simultaneously meet multiple requirements, including determinism in the data flow chain, security of the ABE master key, security of the target node's private key, real-time system services, and reliability and efficiency of the data chain. The performance and efficiency issues of existing technologies are particularly pronounced when handling large-scale, high-frequency cross-border data flows.

[0005] The practical challenges of homomorphic encryption: Homomorphic encryption allows direct computation on ciphertext data, with the decrypted result matching the plaintext result, providing a new approach to access control during data transmission. However, homomorphic encryption operations require significant computational resources. Improving its efficiency in practical applications, while dynamically adjusting the homomorphic operation method and frequency based on cross-border service scenarios, is a major challenge currently facing the technology. Summary of the Invention

[0006] To address the shortcomings of existing data flow access control technologies in meeting the diverse needs of data security, compliance, and efficient transmission in cross-border information services, this invention aims to develop a new technology capable of precisely controlling data flow permissions, ensuring the correctness of data transmission direction and chain, and simultaneously improving data transmission efficiency and security—a pressing need in the field of data security. This invention specifically addresses this need by proposing a cross-border data flow access control system and method based on homomorphic encryption and blockchain technology, aiming to solve key problems in existing technologies and enhance the security and compliance of cross-border data flows.

[0007] The technical solution adopted by this invention to solve the technical problem is: a dynamic control system for cross-border data flow permissions based on homomorphic encryption and blockchain, comprising: The homomorphic encryption module is used to generate homomorphic encryption public and private keys, and publish the homomorphic encryption public key to the blockchain network. Each trusted node obtains the homomorphic encryption public key for business calculation from the blockchain network and performs homomorphic encryption on the data to form encrypted data. The data transmission module is used by each node to perform homomorphic computation on the encrypted data using the homomorphic public key, and then transmits the encrypted computation result to the verification server for verification. The data verification module, located on the verification server, is used to receive the encrypted operation result, decrypt it using a homomorphic private key to obtain the encrypted operation result, perform plaintext operation to obtain the plaintext operation result, compare the encrypted operation result with the plaintext operation result, and send data operation instructions based on the comparison result. The blockchain permission management module is used to record and manage the data transmission and reading permissions of each node based on blockchain technology, and dynamically adjusts the data transmission and reading permissions of nodes through a heartbeat mode.

[0008] The homomorphic encryption module further includes: a key generation unit for generating homomorphic encryption public and private keys; a public key publishing unit for publishing the homomorphic encryption public key to the blockchain network; a public key acquisition unit for each trusted node to acquire the homomorphic encryption public key for business computation from the blockchain network; and a data encryption unit for the data transmission party to verify the data and perform homomorphic encryption to form encrypted data.

[0009] The data verification module further includes: a cryptographic decryption unit, used to decrypt the cryptographic operation result using a homomorphic private key to obtain the cryptographic operation result; a plaintext operation unit, used to perform plaintext operation to obtain the plaintext operation result; and a result comparison unit, used to compare the cryptographic operation result with the plaintext operation result and send data operation instructions to the data node based on the comparison result.

[0010] The blockchain permission management module further includes: a permission recording unit, used to record the data transmission and reading permissions of each node based on blockchain technology; a heartbeat communication unit, used to verify that the server communicates with each node via heartbeat in each fixed period to transmit and update parameters; and a permission adjustment unit, used to dynamically adjust the data transmission and reading permissions of nodes based on the parameters received during the heartbeat communication process.

[0011] The heartbeat communication unit further includes: a period setting subunit for setting a fixed period time; and a communication execution subunit for executing heartbeat communication between the verification server and each node within each fixed period.

[0012] The permission adjustment unit further includes: a homomorphic operation count adjustment subunit, used to increase or decrease the homomorphic operation count of nodes according to actual needs; a data transmission permission adjustment subunit, used to dynamically adjust the data transmission permissions of nodes according to security policies; and a read permission adjustment subunit, used to dynamically adjust the read permissions of target nodes according to security policies.

[0013] A method for dynamic control of cross-border data flow permissions based on homomorphic encryption and blockchain includes the following steps: S1. Generate a homomorphic encryption public key and private key, and publish the homomorphic encryption public key to the blockchain network. Each trusted node obtains the homomorphic encryption public key for business calculation from the blockchain network and performs homomorphic encryption on the data to form encrypted data. S2. Each node uses a homomorphic public key to perform homomorphic computation on the encrypted data and transmits the encrypted computation result to the verification server for verification. S3. The verification server receives the encrypted operation result, decrypts it using the homomorphic private key to obtain the encrypted operation result, performs plaintext operation to obtain the plaintext operation result, compares the encrypted operation result with the plaintext operation result, and sends data operation instructions based on the comparison result. S4. Based on blockchain technology, record and manage the data transmission and reading permissions of each node, and dynamically adjust the data transmission and reading permissions of the nodes through heartbeat mode.

[0014] The step of dynamically adjusting the data transmission and read permissions of nodes through heartbeat patterns also includes: A1. Set a fixed periodic time; A2. During each fixed period, the verification server communicates with each node via heartbeat to transmit and update parameters; A3. Based on the received parameters, dynamically adjust the node's data transmission and read permissions.

[0015] The step of homomorphically encrypting data to form encrypted data further includes: the data transmission party verifying the data; and using the homomorphic encryption public key to encrypt the verified data to form encrypted data.

[0016] The verification server receives the encrypted operation result, decrypts it using a homomorphic private key, performs a plaintext operation to obtain the plaintext operation result, compares the encrypted operation result with the plaintext operation result, and sends a data operation instruction based on the comparison result. The steps also include: if the encrypted operation result and the plaintext operation result are consistent, sending an instruction to the data node to agree to continue the next step of data operation; if the encrypted operation result and the plaintext operation result are inconsistent, sending an instruction to the data node to stop the data operation.

[0017] The cross-border data flow access control system and method based on homomorphic encryption and blockchain technology proposed in this invention have the following significant advantages compared with existing technologies: This invention constructs a strict data flow path control mechanism by combining homomorphic encryption and blockchain technology. During cross-border data transmission, data always flows along a preset path and nodes; any attempt to deviate from the preset path will be identified and blocked by the system. Simultaneously, the immutability of blockchain ensures the integrity and traceability of the data flow chain, effectively preventing data leakage and unauthorized access, and meeting the stringent compliance requirements of cross-border data flows.

[0018] This invention employs homomorphic encryption to encrypt data, ensuring that the data remains encrypted throughout transmission. Even if the data is intercepted, attackers cannot obtain its true content. Furthermore, by dynamically generating and distributing decryption private keys, combined with blockchain smart contract technology, this invention ensures the security and uniqueness of the private keys, further enhancing data transmission security. This dual encryption mechanism effectively protects user privacy and reduces the risk of data leakage.

[0019] This invention overcomes the limitations of traditional access control models by combining Attribute-Based Encryption (ABE) with homomorphic encryption to achieve a more flexible and fine-grained access control policy. Data owners can define complex access policies for different users or user groups according to actual needs, ensuring that only users who meet specific conditions can access and decrypt data. This fine-grained access management mechanism improves the security and flexibility of data use.

[0020] This invention significantly improves the system's computational efficiency and response speed by optimizing homomorphic encryption algorithms and blockchain consensus mechanisms. While ensuring data security, it achieves real-time system services, meeting the demands of high-frequency, large-scale data transmission in cross-border data flows. Furthermore, the distributed ledger nature of blockchain ensures the reliability and attack resistance of the data chain; even if some nodes fail or are attacked, the normal operation of the entire system will not be affected.

[0021] To address the issue of high computational resource consumption in homomorphic encryption technology, this invention proposes an optimized homomorphic operation scheme. By dynamically adjusting the homomorphic operation method and number of operations, the consumption of computational resources is effectively reduced. Furthermore, by incorporating the lightweight node design of blockchain, the system burden is further reduced, improving overall performance. This optimization scheme enables the invention to maintain efficient and stable operation when handling large-scale cross-border data flows.

[0022] The system architecture designed in this invention possesses excellent scalability and adaptability, easily handling cross-border data flow needs of varying scales and scenarios. Through modular design, the system can easily add new functional modules or adjust existing modules to adapt to constantly evolving data security standards and compliance requirements. Furthermore, this invention supports the integration of multiple encryption algorithms and access control policies, providing users with a more flexible and personalized data security solution. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the data transmission link verification technology based on homomorphic encryption in this invention; Figure 2 This is a schematic diagram of the ABE read permission generation based on blockchain in this invention; Figure 3 Design diagram of a blockchain-based homomorphic operation control system. Detailed Implementation

[0024] In the context of cross-border data flow, to ensure the security, controllability, and compliance of data transmission, this invention proposes a dynamic control system and method for cross-border data flow permissions based on homomorphic encryption and blockchain. The following detailed description of specific embodiments, in conjunction with the accompanying drawings, illustrates the specific implementation of this invention.

[0025] Figure 1The overall process of data transmission link verification technology based on homomorphic encryption is demonstrated. The data transmission party first generates a homomorphic encryption public key and private key, and publishes the public key to the blockchain network. After each trusted node obtains the public key from the blockchain, it performs homomorphic encryption on the data to form encrypted data. During the data transmission process, each node uses the homomorphic public key to perform homomorphic computation on the encrypted data and transmits the result to the verification server for verification. The verification server ensures the correctness and integrity of the data transmission by decryption and comparison.

[0026] Figure 2 This demonstrates how to use blockchain technology to generate and manage attribute-based encryption (ABE) read permissions; by leveraging the immutability and traceability of the blockchain, it ensures that only nodes that meet specific attribute conditions can obtain the right to decrypt data, thereby enhancing the security of data reading.

[0027] Figure 3 This paper details the overall architecture of a blockchain-based homomorphic computation control system. The system comprises several components, including a homomorphic encryption module, a data transmission module, a data verification module, and a blockchain access control module. Each module utilizes blockchain technology to achieve encrypted data transmission, homomorphic computation, result verification, and access control, ensuring the security and controllability of data during cross-border flows.

[0028] A dynamic control system for cross-border data flow permissions based on homomorphic encryption and blockchain mainly consists of four modules: a homomorphic encryption module, a data transmission module, a data verification module, and a blockchain permission management module. The homomorphic encryption module generates homomorphic encryption public and private keys, publishes the public key to the blockchain network, and allows trusted nodes to obtain the public key for business computation from the blockchain network to homomorphically encrypt data, forming encrypted data. The data transmission module allows nodes to perform homomorphic computations on the encrypted data using the public key and transmit the results to a verification server for verification. The data verification module, located on the verification server, receives the encrypted computation results, decrypts them using the private key, performs plaintext computations, compares the encrypted and plaintext results, and sends data operation instructions based on the comparison. The blockchain permission management module records and manages the data transmission and reading permissions of each node using blockchain technology, dynamically adjusting these permissions through a heartbeat mechanism. All modules work collaboratively to ensure the security and controllability of data during cross-border flows.

[0029] The homomorphic encryption module further includes a key generation unit, a public key distribution unit, a public key acquisition unit, and a data encryption unit. The key generation unit is responsible for generating the public and private key pairs required for homomorphic encryption; the public key is used to encrypt data, and the private key is used for decryption and verification. The public key distribution unit publishes the generated homomorphic encryption public key to the blockchain network, ensuring that each trusted node can obtain the latest public key information. The public key acquisition unit allows each trusted node to obtain the homomorphic encryption public key used for this business calculation from the blockchain network. In the data encryption unit, the data transmission party uses the acquired public key to homomorphically encrypt the verified data, forming encrypted data to ensure the confidentiality of the data during transmission. In the data transmission module, each node (including relay nodes and target nodes) uses the homomorphic public key to perform homomorphic computation on the received encrypted data. Homomorphic computation allows operations on ciphertext without decryption, maintaining data confidentiality. After the computation is completed, each node transmits the encrypted computation result to the verification server for verification, ensuring the correctness and integrity of the data transmission.

[0030] The data verification module (located on the verification server) includes the following functional units: The encrypted decryption unit uses a homomorphic private key to decrypt the received encrypted operation result and recover the original operation result; the plaintext operation unit performs plaintext operation on the original data to obtain the expected operation result; the result comparison unit compares the encrypted decryption operation result with the plaintext operation result and sends data operation instructions (such as continue transmission or stop transmission) to the data node according to the comparison result.

[0031] The blockchain permission management module includes the following functional units: a permission recording unit, which records and manages the data transmission and reading permissions of each node based on blockchain technology, ensuring the immutability and traceability of permission information; a heartbeat communication unit, which verifies that the server communicates with each node in a fixed period to transmit and update permission parameters, ensuring the real-time performance and effectiveness of permission management; and a permission adjustment unit, which dynamically adjusts the data transmission and reading permissions of nodes based on the parameters received during the heartbeat communication, including the number of homomorphic operations and the increase or decrease of data transmission and reading permissions.

[0032] Example: Application of digital access control technology based on homomorphic encryption In this embodiment, during the authorized data flow process, the data will pass through multiple relay nodes and target nodes. More specifically, it utilizes the aforementioned cross-border data flow permission dynamic control system based on homomorphic encryption and blockchain, namely, digital permission control technology based on homomorphic encryption, to ensure the accuracy and security of data transmission and data reading permissions for each node. This involves two aspects: first, verifying whether each relay node and target node has data transmission rights; and second, ensuring that each node follows the permission control rules during data reading. The specific technical solution execution path is as follows: Figure 1-3 As shown: A method for dynamic control of cross-border data flow permissions based on homomorphic encryption and blockchain. The core logic of its data transmission link verification technology based on homomorphic encryption is that the result of homomorphic operation on encrypted data, after decryption, is consistent with the result of the operation on plaintext. This embodiment requires each relay point through which the data flows to perform homomorphic operation and send it to the verification server for verification. Only after successful verification is the data allowed to be transmitted or proceed to the next step. The implementation of this technology is divided into the following three stages and steps: S1. Preparation Phase: In this embodiment, the data transmission party generates a homomorphic encryption public key and private key through the key generation unit of the homomorphic encryption module; the public key publishing unit publishes the public key to the blockchain network for each trusted node to obtain; each trusted node obtains the public key from the blockchain network through the public key acquisition unit; the data transmission party uses the data encryption unit to homomorphically encrypt the verified data to form encrypted data.

[0033] S2. Data transmission stage: In this embodiment, each node uses a homomorphic public key to perform homomorphic computation on the received encrypted data; after the computation is completed, the encrypted computation result is transmitted to the verification server for verification.

[0034] S3, Data Verification Stage: In this embodiment, the verification server uses the homomorphic private key to decrypt the encrypted operation result through the encrypted decryption unit of the data verification module; the plaintext operation unit performs plaintext operation on the original data to obtain the expected result; the result comparison unit compares the operation result after encrypted decryption with the plaintext operation result, and sends a data operation instruction according to the comparison result.

[0035] S4. Permission Management and Dynamic Adjustment Stage: In this embodiment, the permission recording unit of the blockchain permission management module records the initial permission information of each node; the heartbeat communication unit communicates with each node in a fixed period to transmit and update permission parameters; the permission adjustment unit dynamically adjusts the data transmission and reading permissions of the nodes according to the received parameters to ensure the flexibility and real-time nature of permission management.

[0036] The homomorphic encryption module in this embodiment implements data transmission link verification technology based on homomorphic encryption. The specific steps are as follows: Step 1: Generate a key pair: Step 2: Publish the public key, and... Published to the blockchain network; Step 3: Obtain the public key. Each trusted node obtains the homomorphic encrypted public key used for this business computation from the blockchain network. ; Step 4: Data verification by the data transmission party Homomorphic encryption is performed to form dense data. During the data transmission phase, each node uses its homomorphic public key to perform homomorphic computation on the encrypted data: … When the data is transmitted to the node that needs to be verified, the result of the encrypted operation will be transmitted to the verification server for verification.

[0037] Data verification phase. After receiving the homomorphic operation data for verification, the verification server uses the homomorphic private key to decrypt the encrypted data and obtain the result of the encrypted operation.

[0038] At the same time, the verification server performs plaintext calculations and obtains the plaintext calculation results.

[0039] Finally, the results of the encrypted operation are compared with the results of the plaintext operation. If Then send a message to the data node agreeing to continue the data operation.

[0040] In this embodiment, the blockchain-based ABE data read access control technology in the data transmission module is based on the core idea that when data is transmitted to the target node, the target node checks its own attributes using its private key to see if they meet the encrypted access policy. The target node's attributes are divided into two parts: one part is attributes unique to the target node, such as the network card physical address; the other part is attributes transmitted to the target node server in encrypted form by the cryptographic server.

[0041] This embodiment ensures that the target node's attributes meet the expected data read control requirements. Furthermore, by controlling dynamic attribute values, it allows the data transmitter to control whether the target node has permission to read cross-border e-government data before data reception, thereby increasing the security and reliability of cross-border e-government data transmission. The detailed explanation of this solution is as follows: Encryption creation stage. Random selection. Calculate the ciphertext: in This is an attribute of the destination server, used to calculate the master key component: Simultaneously calculate the key component of dynamic attributes: Component for calculating target node server attribute keys: Ciphertext is generated using a key component: Authorization Confirmation Phase. Following the homomorphic encryption-based data transmission link verification in the previous step, after verifying the determinism of the transmission link, the cryptographic server will synchronously download the target node's public key from the blockchain server and encrypt the dynamic attribute value. The encrypted secret component value is transmitted to the target node.

[0042] Data reading phase. The target node decrypts using the private key to obtain dynamic attributes. Decryption component: Target node server calculates private key Based on the following bilinear mapping used in ciphertext generation: Calculate the intermediate value: Calculate the dynamic decryption component: Calculate the decryption key: Decrypt the data and obtain its content: In this embodiment, the design of the blockchain-based homomorphic operation control system mainly addresses the following three issues: first, controlling the number of homomorphic operations performed on nodes during cross-border transmission of e-government data; second, changing the data transmission permissions of nodes; and third, changing the read permissions of nodes, specifically as follows: Figure 3 As shown, a heartbeat mechanism is used to ensure that the verification server communicates with each node once within a fixed period, transmitting and updating parameters during the communication. This includes the following aspects: Heartbeat mode design. The system sets a fixed period, such as every hour or every minute. Within each fixed period, the verification server communicates with each node once to ensure the real-time performance and synchronization of the system.

[0043] Parameter passing and updating: During heartbeat communication, the verification server transmits necessary parameters to each node, including the number of homomorphic operations, data transmission permissions, and read permissions. Each node updates accordingly based on the received parameters to ensure that the node state is consistent with the system requirements.

[0044] At the same time, the number of homomorphic operations is controlled, allowing the system to arbitrarily increase or decrease the number of homomorphic operations: In this embodiment, regarding data transmission permission management, the system uses blockchain technology to record and manage the data transmission permissions of each node, dynamically adjusting these permissions based on actual needs and security policies. Regarding read permission management, when data is transmitted to the target node, the system verifies the target node's read permissions and dynamically updates them as needed, ensuring that only authorized nodes can read the data. This part primarily controls the attribute values ​​transmitted via a heartbeat mode to control whether the target node can decrypt the data.

[0045] This invention combines homomorphic encryption, attribute-based encryption (ABE), and blockchain technology to form a comprehensive data flow access control solution. It is applicable to fields such as e-government, finance, and healthcare that involve the cross-border flow of large amounts of sensitive data. Through this technology, the access permissions of relay nodes and target nodes in the cross-border data transmission process can be effectively managed, ensuring the correctness of the data flow direction and chain, while improving the efficiency and security of data transmission.

Claims

1. A dynamic control system for cross-border data flow permissions based on homomorphic encryption and blockchain, characterized in that: include: The homomorphic encryption module is used to generate homomorphic encryption public and private keys, and publish the homomorphic encryption public key to the blockchain network. Each trusted node obtains the homomorphic encryption public key for business calculation from the blockchain network and performs homomorphic encryption on the data to form encrypted data. The data transmission module is used by each node to perform homomorphic computation on the encrypted data using the homomorphic public key, and then transmits the encrypted computation result to the verification server for verification. The data verification module, located on the verification server, is used to receive the encrypted operation result, decrypt it using a homomorphic private key to obtain the encrypted operation result, perform plaintext operation to obtain the plaintext operation result, compare the encrypted operation result with the plaintext operation result, and send data operation instructions based on the comparison result. The blockchain permission management module is used to record and manage the data transmission and reading permissions of each node based on blockchain technology, and dynamically adjusts the data transmission and reading permissions of nodes through a heartbeat mode.

2. The cross-border data flow permission dynamic control system based on homomorphic encryption and blockchain according to claim 1, characterized in that: The homomorphic encryption module further includes: The key generation unit is used to generate homomorphic encryption public and private keys; The public key publishing unit is used to publish homomorphic encrypted public keys to the blockchain network; The public key acquisition unit is used by each trusted node to obtain a homomorphic encrypted public key for business computation from the blockchain network. The data encryption unit is used by the data transmission party to verify the data and perform homomorphic encryption to form encrypted data.

3. The cross-border data flow permission dynamic control system based on homomorphic encryption and blockchain according to claim 1, characterized in that: The data verification module also includes: The encrypted decryption unit is used to decrypt the encrypted operation result using a homomorphic private key to obtain the result of the encrypted operation. The plaintext operation unit is used to perform plaintext operations and obtain the plaintext operation results; The result comparison unit is used to compare the encrypted operation result with the plaintext operation result and send data operation instructions to the data node based on the comparison result.

4. The cross-border data flow permission dynamic control system based on homomorphic encryption and blockchain according to claim 1, characterized in that: The blockchain access control module also includes: The permission recording unit is used to record the data transmission and reading permissions of each node based on blockchain technology; The heartbeat communication unit is used to verify that the server communicates with each node in a fixed period to transmit and update parameters. The permission adjustment unit is used to dynamically adjust the data transmission and read permissions of nodes based on the parameters received during the heartbeat communication process.

5. The cross-border data flow permission dynamic control system based on homomorphic encryption and blockchain according to claim 4, characterized in that: The heartbeat communication unit further includes: The period setting subunit is used to set a fixed period time; The communication execution subunit is used to perform heartbeat communication between the verification server and each node in each fixed period.

6. The cross-border data flow permission dynamic control system based on homomorphic encryption and blockchain according to claim 4, characterized in that: The permission adjustment unit further includes: The homomorphic operation count adjustment subunit is used to increase or decrease the number of homomorphic operations on nodes according to actual needs; The data transmission permission adjustment subunit is used to dynamically adjust the data transmission permissions of nodes according to security policies. The read permission adjustment subunit is used to dynamically adjust the read permissions of the target node according to the security policy.

7. A method for dynamic control of cross-border data flow permissions based on homomorphic encryption and blockchain, characterized in that: Includes the following steps: S1. Generate a homomorphic encryption public key and private key, and publish the homomorphic encryption public key to the blockchain network. Each trusted node obtains the homomorphic encryption public key for business calculation from the blockchain network and performs homomorphic encryption on the data to form encrypted data. S2. Each node uses a homomorphic public key to perform homomorphic computation on the encrypted data and transmits the encrypted computation result to the verification server for verification. S3. The verification server receives the encrypted operation result, decrypts it using the homomorphic private key to obtain the encrypted operation result, performs plaintext operation to obtain the plaintext operation result, compares the encrypted operation result with the plaintext operation result, and sends data operation instructions based on the comparison result. S4. Based on blockchain technology, record and manage the data transmission and reading permissions of each node, and dynamically adjust the data transmission and reading permissions of the nodes through heartbeat mode.

8. The method for dynamic control of cross-border data flow permissions based on homomorphic encryption and blockchain according to claim 7, characterized in that: The step of dynamically adjusting the data transmission and read permissions of nodes through heartbeat patterns also includes: A1. Set a fixed periodic time; A2. During each fixed period, the verification server communicates with each node via heartbeat to transmit and update parameters; A3. Based on the received parameters, dynamically adjust the node's data transmission and read permissions.

9. The method for dynamic control of cross-border data flow permissions based on homomorphic encryption and blockchain according to claim 7, characterized in that: The step of homomorphically encrypting data to form encrypted data further includes: the data transmission party verifying the data; and using the homomorphic encryption public key to encrypt the verified data to form encrypted data.

10. The method for dynamic control of cross-border data flow permissions based on homomorphic encryption and blockchain according to claim 7, characterized in that: The verification server receives the encrypted operation result, decrypts it using a homomorphic private key, performs a plaintext operation to obtain the plaintext operation result, compares the encrypted operation result with the plaintext operation result, and sends a data operation instruction based on the comparison result. The steps also include: if the encrypted operation result and the plaintext operation result are consistent, sending an instruction to the data node to agree to continue the next step of data operation; if the encrypted operation result and the plaintext operation result are inconsistent, sending an instruction to the data node to stop the data operation.

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