Block chain-based data access control method for instrument control system

Abstract

The invention belongs to the technical field of data security and block chains, and particularly relates to an instrument control system-oriented block chain-based data access control method, which specifically comprises the following steps that: a secret key generation center generates an attribute-based private key and an access control strategy according to the attribute of a registered user, and the access control strategy is a downward compatible three-layer authority structure; the secret key generation center distributes the private key and the control strategy to corresponding instrument control equipment, and submits the control strategy to a block chain for storage; the instrument control equipment encrypts the generated data according to the received access control strategy, generates encrypted data and a verifiable commitment value, and submits the encrypted data and the verifiable commitment value to the block chain for storage; and the user reads the encrypted data and the access control strategy from the block chain, checks the permission level of the block chain by using the private key, and executes corresponding availability, readability or updatability operation according to the permission level of the block chain.

Description

Technical Field

[0001] This invention belongs to the field of data security and blockchain technology, specifically relating to a blockchain-based data access control method for instrumentation and control systems. Background Technology

[0002] Industrial instrumentation and control systems (ICS) are a core component of industrial automation, responsible for real-time monitoring of key parameters such as temperature, pressure, and flow rate during the production process. They regulate production equipment through controllers to ensure production safety and product quality. In process industries such as chemical, petroleum, and power, ICS generate massive amounts of sensor data and operation logs every second. This data not only records the real-time status of the production process but also includes crucial information such as equipment operating parameters, safety alarm messages, and operator instructions. With the rapid development of the Industrial Internet and intelligent manufacturing, ICS data is of significant value to enterprises in production decision-making, predictive maintenance of equipment, tracing the source of safety incidents, and compliance auditing.

[0003] Traditional instrumentation and control data management typically employs centralized database systems, with system administrators maintaining access control policies. However, this approach suffers from several problems: First, data is easily tampered with and difficult to trace, making it impossible to provide reliable historical records in the event of a security incident; second, access control is coarse-grained, making it difficult to implement fine-grained permission management for different user roles (ordinary operators, engineers, system administrators, etc.); third, access policies are separated from data storage, allowing malicious administrators or compromised centralized services to bypass policy restrictions and provide access to sensitive data to unauthorized users. Especially in complex instrumentation and control environments involving collaboration across multiple business departments, the lack of a unified identity authentication and data access control mechanism across business domains leads to both data silos and security vulnerabilities.

[0004] To address these challenges, leveraging the decentralized, immutable, and auditable characteristics of blockchain technology to construct instrumentation and control data access control schemes has become a research hotspot. While blockchain can provide a tamper-proof storage foundation for instrumentation and control data, achieving fine-grained access control, backward-compatible hierarchical permission management (updatable permissions include readable permissions, and readable permissions include usable permissions), and secure data querying with multi-party participation while ensuring data privacy still faces numerous technical challenges. Existing technologies such as attribute-based encryption, blockchain identity authentication, and data index management, although making progress in their respective fields, are insufficient to simultaneously meet the comprehensive needs of instrumentation and control systems for access control throughout the entire data lifecycle.

[0005] Existing work has explored data access control, identity authentication, and blockchain data management technologies from different perspectives. Regarding data access control, Saha et al.'s paper, "AALMOND: Decentralized Adaptive AccessControl of Multi-Party Data Sharing in Industrial Networks," proposes a decentralized adaptive access control scheme based on blockchain and smart contracts for industrial networks. In terms of identity authentication, Zhang et al.'s paper, "Stateless Blockchain-Based Lightweight Identity Management Architecture for Industrial IoT Applications," proposes a lightweight identity management architecture based on decentralized identifiers for the Industrial Internet of Things (IIoT), while Chen et al.'s paper, "XAuth: Efficient privacy-preserving cross-domain authentication," studies cross-domain privacy-preserving identity authentication, achieving cross-domain identity mutual recognition. Regarding blockchain applications in industrial scenarios, Park et al.'s paper, "BPPS: Blockchain-enabled privacy-preserving scheme for demand-response management in smart grid environments," proposes a blockchain-based privacy protection scheme for smart grid demand response management. In terms of blockchain data management and querying, Li et al.'s paper "FlexIM: Efficient and Verifiable Index Management in Blockchain" optimizes the index structure through reinforcement learning, Sui et al.'s paper "ScorpioBase: An Efficient Batched Blockchain System for Traceability Applications in Supply Chain" uses batch signing to reduce storage overhead, and Zhang et al.'s paper "Earth Observation Data Provenance: A Blockchain-Based Solution" proposes an on-chain and off-chain hybrid storage architecture to improve scalability.Regarding data updability, Zhang et al.'s paper, "Dynamic trust-based redactable blockchain supporting update and traceability," proposes an editable blockchain based on chameleon hashing, allowing users holding trapdoor keys to update data. However, these works either separate access policies from data storage, failing to prevent malicious servers from bypassing the policies, or fail to achieve backward-compatible hierarchical permission management (updatable permissions should include both read and usable permissions), or pose privacy leakage risks in multi-party scenarios. They struggle to simultaneously meet the comprehensive needs of instrumentation and control systems for fine-grained access control, hierarchical permission inheritance, data privacy protection, and controllable updates.

[0006] With the deepening development of the Industrial Internet and intelligent manufacturing, the massive amounts of data generated by instrumentation and control systems are playing an increasingly important role in production decision-making, equipment maintenance, safety traceability, and compliance auditing. This data needs to be securely accessed and managed by users with different roles (operators, engineers, administrators, etc.), while ensuring its authenticity, integrity, and traceability. However, existing technologies for data access control in instrumentation and control systems have the following significant shortcomings: First, the security risks arising from the decoupling of data and policies: Many current data access control methods separate access policies from data storage, with access policies typically stored on centralized servers and maintained by administrators. In attribute-based encryption schemes, although the access policy is embedded in the ciphertext to control decryption permissions, the decrypted data can be arbitrarily stored, disseminated, and used, failing to achieve full lifecycle access control for the data. In industrial IoT identity authentication schemes, although decentralized identity management is achieved, identity authentication and data access permissions are still separated, requiring centralized servers to execute access policies. This architecture allows data storage providers (such as blockchain nodes and servers) to have complete control over the data access process, potentially leading to deliberate violations of data owner policies, providing data services to unauthorized users (such as former employees or users with expired permissions) or directly stealing sensitive data, seriously threatening production safety and data integrity.

[0007] Second, there is a lack of a backward-compatible hierarchical access control mechanism: Existing technologies, when handling hierarchical access control, mostly adopt a method of setting independent access policies and keys for each access level, failing to achieve automatic permission inheritance. In practical instrumentation and control applications, users with data update permissions should be able to perform data read and query operations, and users with data read permissions should be able to perform query operations. However, existing solutions require high-privilege users to obtain multiple sets of keys to perform different levels of operations, which not only does not meet actual business needs but also increases the complexity of key management. Although blockchain access control solutions can set role inheritance relationships through smart contracts, this inheritance relationship lacks cryptographic guarantees and still relies on centralized service execution, failing to prevent malicious servers from performing permission overreach operations. Furthermore, existing solutions lack a unified framework to simultaneously manage data availability, readability, and updability, making it difficult to guarantee consistent security policy implementation.

[0008] Third, insufficient privacy protection and multi-party collaboration: Most existing solutions pose privacy risks throughout the entire lifecycle of data querying, reading, and updating. In blockchain-based data management solutions, to support efficient querying and traceability, data is typically stored in plaintext or simple encryption. Query nodes need to access the original data to build indexes or perform query operations, which may lead to the leakage of sensitive information in scenarios involving multiple parties. While existing homomorphic encryption schemes can perform computations on ciphertext, the decryption key is usually held by a single entity. If this entity is compromised or acts dishonestly, data leakage will occur. Especially in scenarios where instrumentation data query services require multiple servers to collaborate, the lack of effective key splitting and collaborative decryption mechanisms fails to protect data privacy and poses a single point of failure risk. Summary of the Invention

[0009] In view of this, the present invention provides a blockchain-based data access control method for instrumentation and control systems. This method enables instrumentation and control equipment to securely store data on the blockchain, while ensuring the enforcement of data access policies through cryptographic mechanisms.

[0010] The technical solution for implementing the present invention is as follows: A blockchain-based data access control method for instrumentation and control systems, the specific process of which is as follows: Key generation and policy settings: The key generation center generates attribute-based private keys based on registered user attributes. and access control policies The access control policy is a backward-compatible three-tier permission structure, including availability policy, readability policy, and updability policy; the key generation center will use the private key. and control strategies Distribute to the corresponding instrumentation and control equipment, and simultaneously implement the control strategy. Submitted to blockchain storage; Data encryption: Instrumentation and control equipment uses the received access control policy. For the generated data Encryption processing is performed to generate encrypted data. and verifiable commitment value And submit it to the blockchain storage; Data Access and Updates: Users read encrypted data from the blockchain. and access control policies and using the private key Check its permission level and perform the appropriate availability, readability, or updability operations based on its permission level.

[0011] Optionally, the present invention describes performing corresponding availability, readability, or updability operations based on the permission level, specifically as follows: Users with data availability rights submit encrypted query requests to the blockchain. After the smart contract performs homomorphic inference, it sends the ciphertext result to the cloud server for collaborative decryption and returns the plaintext result. Users with data readability permissions can pull encrypted data from the blockchain and decrypt it using the recovered key parameters to obtain plaintext data; After decrypting and updating the data, users with data updability permissions re-encrypt the data, calculate a new chameleon hash random value, and submit the updated encrypted data to the blockchain to achieve verifiable data updates.

[0012] Optionally, the key generation center of this invention uses the user's attribute set. The KeyGen algorithm is executed to generate the user's private key. The specific process is as follows: First, choose random values ,in Indicates the size of the attribute set. Indicates the first Each attribute value; Then, the key generation center calculates the three components of the user's private key ( , , ); Finally, generate the complete user key. .

[0013] Optionally, the key generation center of this invention generates access control policies. The specific process is as follows: First, formulate raw data access control policies. The control strategy uses a tree structure consisting of internal nodes and leaf nodes. Each internal node contains three secret nodes, forming a three-tiered, downward-compatible permission structure: Availability Strategy Readability strategies and updateability strategy ; Secondly, choose a random value. As the root secret of the updability policy, it is achieved through access control policies. Secret sharing mechanism calculation ,in and These are the root secrets of readability and usability strategies, respectively. For the first The secret value of each leaf node. This represents the total number of leaf nodes in the control strategy tree; Next, calculate the parameters for each leaf node. and

[0014]

[0015] Calculate the parameters corresponding to the three secret nodes. and ;

[0016] Finally, the calculated parameters are integrated into the original policy. In the corresponding nodes, the processed control strategy is generated. .

[0017] Optionally, the specific process of data encryption processing in the instrumentation and control equipment of the present invention is as follows: First, choose the Chameleon hash key. and random values And generate homomorphic encryption key pairs. ; Secondly, based on the key Calculate the Chameleon Hash public key and various encryption parameters to obtain the Chameleon Hash commitment value:

[0018]

[0019] in, For the order of Cyclic group generator, This represents a string concatenation operation. Hash all parameters into a finite field The value in the parameter Used to encrypt chameleon hash keys to support updability. Used to encrypt raw data to support readability. Used to encrypt homomorphic public keys to support availability. The original data is homomorphically encrypted with ciphertext; Then, the homomorphic encryption private key Divided into Individual shares , of which One share can recover the original private key, but less than Individual shares cannot obtain any information; key shares are transmitted via a secure channel. Distributed to the One cloud server; Finally, the device will encrypt the data. Chameleon Hash Commitment Value Submit to blockchain storage.

[0020] Optionally, the present invention also includes a data verification stage during the data encryption phase, allowing all participants to read publicly available information from the blockchain. And verify the integrity of the data.

[0021] Optionally, the permission check described in this invention specifically includes: First, if the node These are leaf nodes; users compute the leaf node's value using their private key. :

[0022] Secondly, if the node is an internal node, and the user has already calculated the direct child nodes connected to that internal node... Number greater than Users can combine its child nodes and utilize Lagrange parameters. Calculate the internal node's for:

[0023] Finally, the internal nodes consist of three secret nodes, utilizing the three secret nodes... Calculate the three secret nodes Based on parameters of successful recovery Users determine their permission levels;

[0024] in, .

[0025] Optionally, the user operation process for data availability permissions described in this invention is as follows: First, users with availability permissions use the recovery... Export the homomorphic encryption public key Using homomorphic encryption public key Request the required data Encrypt and submit to the blockchain ; Secondly, smart contracts on the blockchain utilize stored encrypted data. and user submissions Performing a homomorphic operation on the ciphertext field yields the encrypted result. ; Next, encrypt the result. The message is sent to the first cloud server, which decrypts it using its share of the key and then passes it to the second cloud server, and so on, until at least... After partially decrypting the results from each cloud server, the decryption is performed on the aggregated cloud servers, and the final result is returned to the user. .

[0026] Optionally, the user operation process for data readability permissions described in this invention is as follows: The user with readability permissions restored Read encrypted data from the blockchain Restore original data .

[0027] Optionally, the user operation process for data updability permission in this invention is as follows: First, a user with update permissions uses the restore function. Recover the Chameleon hash key ; Secondly, by utilizing backward compatibility permissions, users can... Recovering original data from the blockchain and the data Update to obtain new data ;Utilizing backward compatibility permissions, users can use Recover the homomorphic encryption public key Generate new encrypted data: Secondly, the user uses the Chameleon hash key. Calculate a new chameleon hash random value and generate a new encrypted data packet, which is then submitted to the blockchain to replace the original encrypted data, thus completing the data update.

[0028] Beneficial effects: First, regarding scenario adaptability, existing technologies employ simple read / write binary permissions or role-based access control, which cannot meet the specific needs of industrial instrumentation and control systems. This application proposes a three-tiered permission structure based on usability, readability, and modifiability, precisely matching the different needs of operators (querying and reasoning only), engineers (reading complete data), and administrators (modifying configuration parameters). This fine-grained permission division reduces the risk of data leakage.

[0029] Secondly, regarding the flexibility of access control, existing attribute-based encryption schemes require independent policy and key settings for each access level, necessitating higher-privilege users to acquire multiple sets of keys. This application's three-level nested policy tree design achieves cryptographically guaranteed automatic inheritance of permissions. Higher-privilege users can automatically restore lower-privilege parameters when traversing the policy tree without requiring additional key acquisition, simplifying management while ensuring the enforcement of access boundaries.

[0030] Third, regarding privacy protection in multi-party collaborations, existing technologies either rely on a single entity holding the decryption key, posing a single point of failure risk, or require the data owner to participate in decryption, impacting service efficiency. This application divides the homomorphic encryption private key into multiple shares through threshold secret sharing and distributes them to cloud servers. User-submitted encrypted queries are subjected to homomorphic inference on the ciphertext domain by a blockchain smart contract, then partially decrypted and transmitted sequentially by multiple cloud servers, ultimately aggregating to generate the plaintext result. This design achieves data that is "usable but not visible," as a single cloud server cannot access the plaintext data; only at least... Decryption requires collaboration among multiple servers, effectively preventing single points of failure and coordinated attacks.

[0031] In summary, this application significantly improves the security, flexibility, and practicality of data access control in instrumentation and control systems through technological innovations in areas such as scenario adaptation, backward compatibility permission management, and multi-party collaborative privacy protection. It solves the core problems of existing technologies in industrial applications and has good application and promotion value. Attached Figure Description

[0032] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 System model diagram; Figure 2 This is a flowchart of the workflow of this method; Figure 3 This is a schematic diagram of a policy control tree. Detailed Implementation

[0034] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0035] It should be noted that, unless otherwise specified, the following embodiments and features can be combined with each other; and, based on the embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0036] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this disclosure, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using structures and / or functionalities other than one or more of the aspects set forth herein.

[0037] This application provides a blockchain-based data access control method for instrumentation and control systems. This method enables instrumentation and control equipment to securely store data on the blockchain, while ensuring the enforcement of data access policies through cryptographic mechanisms.

[0038] like Figure 1 As shown, the system model of this method consists of five entities: a key generation center, instrumentation and control equipment, cloud servers, users, and a blockchain. The key generation center, as a trusted authority, is responsible for system initialization, generating master key pairs, authenticating user and device attributes, and issuing user keys. The instrumentation and control equipment is the physical device that generates instrumentation and control data. After receiving data access control policies, it automatically encrypts the generated data and distributes the homomorphic encryption key to multiple cloud servers. The cloud servers collaborate to perform data query operations using their respective key shares, completing decryption calculations without obtaining plaintext data. Users, as data consumers, are divided into four categories based on their permission levels: unauthorized users, usability users (can query or use), readable users (can read complete data), and updatable users (can update data). The blockchain, as a decentralized storage and auditing platform, stores encrypted instrumentation and control data, data hash values, and metadata, providing publicly verifiable data integrity guarantees for the entire system.

[0039] like Figure 2As shown in the figure, this application provides a blockchain-based data access control method for instrumentation and control systems, which mainly includes four core stages: system initialization, key generation and policy setting, data encryption and verification, and data access.

[0040] During the system initialization phase, the key generation center generates master key pairs and system public parameters (i.e., bilinear mapping parameters and hash functions) and publishes them to the blockchain.

[0041] During the key generation and policy setting phase, users register their attribute information with the key generation center and obtain the corresponding private key. At the same time, the key generation center formulates access control policies and stores them on the blockchain. The control policies are then sent to the instrumentation and control equipment.

[0042] During the data encryption and verification phase, the instrumentation and control equipment performs homomorphic encryption on the data according to the control strategy, generating encrypted data, chameleon hash values ​​and encryption parameters, and submits them to the blockchain for storage. At the same time, the homomorphic encryption key is divided into multiple shares and distributed to each cloud server. All participants can verify the integrity of the data through the public information on the blockchain.

[0043] During the data access and update phase, users first use their private key to traverse the access policy tree to verify their permission level, and then perform corresponding operations according to their permissions: (1) Availability: Users submit encrypted query requests to the blockchain, and the smart contract performs homomorphic inference and sends the ciphertext result to the cloud server for collaborative decryption and returns the plaintext result; (2) Readability: Users pull encrypted data from the blockchain and use the recovered key parameters to decrypt and obtain plaintext data; (3) Updability: After decrypting the data and completing the update, users re-encrypt the data and calculate a new chameleon hash random value, and submit the updated encrypted data to the blockchain to realize the verifiable update of the data.

[0044] This embodiment ensures the cryptographic enforcement of data access policies, achieves backward-compatible access control, and protects data privacy and integrity through multi-party collaboration and blockchain storage.

[0045] The above process will be explained in detail below: Initialization: In this phase, the key generation center performs system initialization operations, establishing the cryptographic foundation for the entire system. The key generation center performs these operations based on security parameters. Execute the Setup algorithm to generate the master key. and the master key The master key contains two keys within a finite field. A secret value randomly selected from... and public key This includes bilinear mapping parameters and a hash function, specifically defined as follows:

[0046] in, It is a bilinear mapping tuple. Define a finite field for large prime numbers , For the order of Cyclic group generator, For bilinear mappings to satisfy the bilinear property The three hash functions are defined as follows: Map strings of arbitrary length to groups The elements in Group The elements in the mapping are mapped to binary strings. Mapping strings of arbitrary length to finite fields The elements in the key generation center will include the master public key. Published to the blockchain for use by all participants, master key The confidential storage is only for use by the key generation center.

[0047] Key generation and policy setting: In this stage, users register with the key generation center and obtain attribute-based private keys. At the same time, the key generation center formulates access control policies and distributes them to instrumentation and control devices.

[0048] User Registration: Users submit their attribute set to the key generation center. Registration is then completed. The key generation center first verifies the authenticity of the user's identity and attributes, and then calls the KeyGen algorithm to generate a corresponding private key for that user. The key generation center transmits the private key through a secure channel. Distribute to users. Once a user receives the private key, they can use it to access data that satisfies their set of attributes.

[0049] KeyGen (Key Generation): Based on the user's attribute set. The key generation center executes the KeyGen algorithm to generate user private keys. The algorithm first selects random values ,in Indicates the size of the attribute set. Indicates the first Each attribute value. Then, the key generation center calculates the three components of the user's private key:

[0050]

[0051]

[0052] in, and These represent the master key; Finally, a complete user key is generated. .

[0053] PolicySet: The key generation center sets the raw data access control policy. The access control policy is a tree structure, consisting of internal nodes (non-leaf nodes) and leaf nodes. Three of the internal nodes are secret nodes, forming a three-tiered, backward-compatible permission structure: Availability Policy Readability strategies and updateability strategy Satisfying the containment relationship The key generation center selects a random value. The root secret, serving as the updateability strategy, is computed through the secret-sharing mechanism of the access control tree. ,in and These are the root secrets of readability and usability strategies, respectively. For the first The secret value of each leaf node, such as Figure 3 As shown. For each leaf node in the access control tree Key generation center calculates the following parameters:

[0054] in, This indicates the number of leaf nodes in the control policy tree.

[0055] For the three secret nodes (corresponding to updability, readability, and availability respectively), the key generation center calculates:

[0056] These parameters Integrate into the original strategy In the corresponding nodes, the processed strategy is generated. The key generation center will process the strategy. Stored on the blockchain, and control policies Send it to the corresponding instrumentation and control equipment.

[0057] Data encryption and verification: In this stage, the instrumentation and control equipment encrypts the generated data according to the received access control policy and generates a verifiable commitment value, which can be verified by all participants to ensure the integrity of the data.

[0058] DataPro (Data Processing): Instrumentation and control equipment receives access control policies from the key generation center. The generated industrial data The ModelPro algorithm is used for encryption. First, the device selects a Chameleon hash key. and random values And generate homomorphic encryption key pairs. The device calculates the Chameleon hash public key and various encryption parameters:

[0059]

[0060]

[0061]

[0062]

[0063] in, This represents a homomorphic encryption algorithm. This indicates an XOR operation. (Parameters) Used to encrypt chameleon hash keys to support updability. Used to encrypt raw data to support readability. Used to encrypt homomorphic public keys to support availability. The original data is homomorphically encrypted with ciphertext. The device calculates the Chameleon Hash Promise value:

[0064] in, This represents a string concatenation operation. Hash all parameters into a finite field The value in the middle. The equipment utilizes... The threshold secret sharing scheme homomorphically encrypts the private key. Divided into Individual shares , of which One share can recover the original private key, but less than Each share cannot obtain any information. The device transmits the key share via a secure channel. Distributed to the A cloud server. Finally, the device will encrypt the data. Chameleon Hash Commitment Value Submit to blockchain storage.

[0065] IntCheck (Integrity Check): In this step, all participants can also read public information from the blockchain. To verify the integrity of the data, participants execute the IntCheck algorithm, utilizing the one-way verification equation of chameleon hashing:

[0066] because The above equation is equivalent to:

[0067] If the equation is true, the verification passes, indicating that the encrypted data... The data has not been tampered with; otherwise, it indicates that the data may have been maliciously modified. Due to the one-way nature of chameleon hashes, the trapdoor key is unknown. In such cases, attackers cannot forge encrypted data that satisfies verification.

[0068] Data access: In this stage, users first verify their access permissions, and then perform corresponding data operations according to their permission levels, including data querying, data reading, and data updating and modification.

[0069] PriCheck (Permission Check): Users read encrypted data from the blockchain. and access control policies Using private key Check its permission level.

[0070] User access control policy This allows us to determine whether each node in the policy tree is a leaf node, an internal node, or a secret node. The user traverses the policy tree from bottom to top. The calculations are performed on each node.

[0071] If node Leaf node user computation :

[0072] If node Is the threshold value An internal node, and the user has already calculated the child nodes directly connected to that internal node. Number greater than Users can combine its child nodes and utilize Lagrange parameters. Calculate the internal node's :

[0073] If node If it is a secret node, then for each ,parameter for User calculation:

[0074] Based on parameters of successful recovery ( The user determines their permission level, where These correspond to updateability, readability, and usability permissions, respectively.

[0075] DataAvail (Data Availability): Users with availability permissions can use the recovery function. Export the homomorphic encryption public key:

[0076] The user prepares a request that needs to process data. Encrypt it using a homomorphic encryption public key. And submit it to the blockchain. Smart contracts on the blockchain utilize the stored encrypted data. and user submissions Performing a homomorphic operation on the ciphertext field yields the encrypted result. Smart contracts will Send to the first cloud server. The first cloud server uses its key share. Decryption of the execution part:

[0077] The first cloud server will contain part of the decryption results. It is passed to the second cloud server, and the second cloud server uses it. Continue with partial decryption, proceeding sequentially. When enough partial decryption results have been collected (at least...),... After (one), perform aggregate decryption:

[0078] in, This represents a partial decryption algorithm. This represents a partial decryption aggregation algorithm. Final result. Return it to the user.

[0079] DataRead: This function allows users with readability permissions to restore data. Read encrypted data from the blockchain Restore the original data:

[0080] Users obtain raw instrumentation and control data The plaintext.

[0081] DataUp: A recovery function used by users with update permissions. Recover the Chameleon hash key:

[0082] Due to backward compatibility with the permission design, users with updateability permissions can also restore [their accounts]. Further recovery To read data, the user through Read from the blockchain Recover the original data :

[0083] Users update the data to obtain new data. Users use homomorphic encryption public keys (pass (Recovered) Generate new encrypted data and :

[0084]

[0085] User based on Chameleon hash key Calculate the new chameleon hash random value:

[0086] User generates new encrypted data packets And submit it to the blockchain. The blockchain system uses... Replace the original Complete the data update.

[0087] Due to the collision properties of chameleon hashing, the updated commitment value remains unchanged, and all participants can still verify data integrity using the IntCheck algorithm.

[0088] This method combines cryptographic techniques such as access control trees, chameleon hashing, and homomorphic encryption to achieve strong coupling between data and policies, and supports backward-compatible hierarchical permission management.

[0089] This invention proposes a blockchain-based data access control method for instrumentation and control systems. Addressing the shortcomings of existing technologies in decoupling data and policies, insufficient granularity of access control, and weak privacy protection in multi-party collaboration, it proposes innovative solutions and technical implementations, specifically including the following aspects: 1. A Three-Tier Data Access Control Framework for Instrumentation and Control Systems: This invention deeply analyzes the actual business scenarios of instrumentation and control systems and innovatively proposes a three-tier permission structure: availability, readability, and modifiability. Availability permissions allow querying and reasoning on instrumentation and control data but cannot obtain the original plaintext; readability permissions allow reading the complete plaintext data but cannot modify historical records; and modifiability permissions allow updating data and ensure verifiability.

[0090] 2. Downward Compatibility Permission Management Mechanism Based on a Three-Level Nested Policy Tree: This invention innovatively designs a three-level nested policy tree structure, where usability policies are subtrees of readability policies, and readability policies are subtrees of modifiability policies. When traversing the policy tree, high-privilege users can simultaneously recover key parameters from multiple levels using the nested structure, inheriting the operational capabilities of low-privilege users.

[0091] 3. Multi-party collaborative data availability service based on threshold key segmentation and on-chain homomorphic inference: This invention innovatively segments the homomorphic encrypted private key into multiple shares through threshold secret sharing and distributes them to cloud servers. The encrypted query submitted by the user is obtained by the blockchain smart contract performing homomorphic inference on the ciphertext domain. Then, multiple cloud servers sequentially perform partial decryption and transmission, and finally aggregate to generate plaintext results.

[0092] Therefore, the present invention can solve the following problems: The first is how to achieve strong coupling between data and policy: bind the data access policy to the data itself through cryptographic mechanisms, so that any data access operation (query, read, update) must meet the policy constraints, and blockchain nodes and servers cannot bypass the policy to execute unauthorized operations.

[0093] Secondly, how to achieve backward compatible access control: design a unified cryptographic framework to implement an updatable > readable > usable access control hierarchy, ensuring that high-privilege users can automatically inherit low-privilege operation capabilities, while preventing access violations and simplifying key management complexity.

[0094] Third, how to protect data privacy throughout the entire process: Protect data privacy throughout the entire lifecycle of data storage, query, retrieval and updating. Through key splitting and multi-party collaborative decryption mechanisms, secure data querying can be achieved without the participation of the data owner, while preventing single points of failure and collusion attacks.

[0095] This invention comprehensively solves the aforementioned technical problems by proposing a data access control method for instrumentation and control systems based on access control trees, chameleon hashing, and homomorphic encryption. This solution, through optimized cryptographic techniques and blockchain storage mechanisms, not only achieves strong coupling between data and policies and backward-compatible access management, but also significantly enhances data privacy protection capabilities through a multi-party collaboration mechanism.

[0096] In summary, the above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A blockchain-based data access control method for instrumentation and control systems, characterized in that, The specific process is as follows: Key generation and policy settings: The key generation center generates attribute-based private keys based on registered user attributes. and access control policies The access control policy is a backward-compatible three-tier permission structure, including availability policy, readability policy, and updability policy; the key generation center will use the private key. and control strategies Distribute to the corresponding instrumentation and control equipment, and simultaneously implement the control strategy. Submitted to blockchain storage; Data encryption: Instrumentation and control equipment uses the received access control policy. For the generated data Encryption processing is performed to generate encrypted data. and verifiable commitment value And submit it to the blockchain storage; Data Access and Updates: Users read encrypted data from the blockchain. and access control policies and using the private key Check its permission level and perform the appropriate availability, readability, or updability operations based on its permission level.

2. The blockchain-based data access control method for instrumentation and control systems according to claim 1, characterized in that, The specific steps for performing appropriate availability, readability, or updability operations based on the user's permission level are as follows: Users with data availability rights submit encrypted query requests to the blockchain. After the smart contract performs homomorphic inference, it sends the ciphertext result to the cloud server for collaborative decryption and returns the plaintext result. Users with data readability permissions can pull encrypted data from the blockchain and decrypt it using the recovered key parameters to obtain plaintext data; After decrypting and updating the data, users with data updability permissions re-encrypt the data, calculate a new chameleon hash random value, and submit the updated encrypted data to the blockchain to achieve verifiable data updates.

3. The blockchain-based data access control method for instrumentation and control systems according to claim 2, characterized in that, The key generation center uses the user's attribute set The KeyGen algorithm is executed to generate the user's private key. The specific process is as follows: First, choose random values ,in Indicates the size of the attribute set. Indicates the first Each attribute value; Then, the key generation center calculates the three components of the user's private key ( , , ); Finally, generate the complete user key. .

4. The blockchain-based data access control method for instrumentation and control systems according to claim 3, characterized in that, The key generation center generates access control policies. The specific process is as follows: First, formulate raw data access control policies. The control strategy uses a tree structure consisting of internal nodes and leaf nodes. Each internal node contains three secret nodes, forming a three-tiered, downward-compatible permission structure: Availability Strategy Readability strategies and updateability strategy ; Secondly, choose a random value. As the root secret of the updability policy, it is achieved through access control policies. Secret sharing mechanism calculation ,in and These are the root secrets of readability and usability strategies, respectively. For the first The secret value of each leaf node. This represents the total number of leaf nodes in the control strategy tree; Next, calculate the parameters for each leaf node. and Calculate the parameters corresponding to the three secret nodes. and ; Finally, the calculated parameters are integrated into the original policy. In the corresponding nodes, the processed control strategy is generated. .

5. The blockchain-based data access control method for instrumentation and control systems according to claim 4, characterized in that, The specific process of data encryption processing for instrumentation and control equipment is as follows: First, choose the Chameleon hash key. and random values And generate homomorphic encryption key pairs. ; Secondly, based on the key Calculate the Chameleon Hash public key and various encryption parameters to obtain the Chameleon Hash commitment value: in, For the order of Cyclic group generator, This represents a string concatenation operation. Hash all parameters into a finite field The value in the parameter Used to encrypt chameleon hash keys to support updability. Used to encrypt raw data to support readability. Used to encrypt homomorphic public keys to support availability. The original data is homomorphically encrypted with ciphertext; Then, the homomorphic encryption private key Divided into Individual shares , of which One share can recover the original private key, but less than Each share cannot obtain any information; key shares are transmitted via a secure channel. Distributed to the One cloud server; Finally, the device will encrypt the data. Chameleon Hash Commitment Value Submit to blockchain storage.

6. The blockchain-based data access control method for instrumentation and control systems according to claim 5, characterized in that, The data encryption phase also includes a data verification step, where all participants can read publicly available information from the blockchain. And verify the integrity of the data.

7. The blockchain-based data access control method for instrumentation and control systems according to claim 4, characterized in that, The specific details of the permission check are as follows: First, if the node These are leaf nodes; users use their private keys to compute the leaf node's... : Secondly, if the node is an internal node, and the user has already calculated the direct child nodes connected to that internal node... Number greater than Users can combine its child nodes and utilize Lagrange parameters. Calculate the internal node's for: Finally, the internal nodes consist of three secret nodes, utilizing the three secret nodes... Calculate the three secret nodes Based on parameters of successful recovery Users determine their permission levels; in, .

8. The blockchain-based data access control method for instrumentation and control systems according to claim 7, characterized in that, The user operation process for the data availability permission is as follows: First, users with availability permissions use the recovery... Export the homomorphic encryption public key Using homomorphic encryption public key Request the required data Encrypt and submit to the blockchain ; Secondly, smart contracts on the blockchain utilize stored encrypted data. and user submissions Performing a homomorphic operation on the ciphertext field yields the encrypted result. ; Next, encrypt the result. The message is sent to the first cloud server, which decrypts it using its share of the key and then passes it to the second cloud server, and so on, until at least... After partially decrypting the results from each cloud server, the decryption is performed on the aggregated cloud servers, and the final result is returned to the user. .

9. The blockchain-based data access control method for instrumentation and control systems according to claim 8, characterized in that, The user operation process for the data readability permission is as follows: The user with readability permissions restored Read encrypted data from the blockchain Restore original data .

10. The blockchain-based data access control method for instrumentation and control systems according to claim 8 or 9, characterized in that, The user operation process for data updability permissions is as follows: First, a user with update permissions uses the restore function. Recover the Chameleon hash key ; Secondly, by utilizing backward compatibility permissions, users can... Recovering original data from the blockchain and the data Update to obtain new data ;Utilizing backward compatibility permissions, users can use Recover the homomorphic encryption public key Generate new encrypted data; Secondly, the user uses the Chameleon hash key. Calculate a new chameleon hash random value and generate a new encrypted data packet, which is then submitted to the blockchain to replace the original encrypted data, thus completing the data update.

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