A BOM-based cross-organization engineering data security collaborative editing method

Abstract

This invention discloses a cross-organizational collaborative editing method for engineering data security based on Bill of Materials (BOM). The method first involves a Trusted Institution (TA) setting global parameters and generating a master key. Participating companies register with the TA, forming a consortium blockchain and deploying smart contracts. Next, the company initiating the collaborative project acts as the lead company, selecting a Service Provider Corporation (SPC). The SPC's public key is bound to a secret shared structure, and the lead company completes data encryption and encapsulation. Then, during the data sharing phase, two processes are included: data decryption and encrypted update. When the service provider company makes modifications, a joint approval process is triggered. Finally, the service provider company can perform multi-version access and trace the behavior when retrieving data entities. This invention effectively solves three core problems faced in cross-organizational collaborative manufacturing scenarios: difficulty in fine-grained sharing, uncontrollable modification authorization, and difficulty in defining and tracing operational responsibility.

Description

Technical Field

[0001] This invention relates to the fields of intelligent manufacturing and data security technology, specifically to a cross-organizational collaborative editing method for engineering data security based on BOM (Bill of Materials) in the manufacturing supply chain. Background Technology

[0002] With the development of intelligent manufacturing, cross-organizational collaborative manufacturing has become an important model for improving product development efficiency. Engineering data such as engineering drawings and 3D models need to be frequently shared, modified, and integrated among multiple parties. However, many enterprises still use traditional methods such as offline copying and intranet isolation for data collaboration, resulting in low collaboration efficiency. This also leads to problems such as difficulty in achieving fine-grained sharing of engineering data, unclear responsibility definition after seamless data fusion, and difficulty in tracing the operational process.

[0003] Existing technologies primarily employ full-file encryption and system-level access control, treating engineering data as an indivisible whole while ignoring its hierarchical structure (such as bills of materials), thus failing to achieve on-demand, fine-grained sharing. Furthermore, CAD drawings and other files are massive in size, making traditional encryption and decryption costly and scalable. While attribute-based encryption and proxy re-encryption mechanisms support some fine-grained control, they are mainly geared towards small documents or sensor data, struggling to adapt to the massive volume and hierarchical nature of engineering data. In addition, existing cross-organizational collaborative editing solutions focus primarily on data integrity, lacking reliable verification and accountability for modifications. It is difficult to distinguish contributions after multiple modifications, and it is impossible to trace responsibility in cases of data errors or infringement. Although commercial platforms support collaborative bills of materials editing, their centralized architecture lacks cross-organizational cryptographic verifiability, failing to provide irrefutable evidence of modifications. Overall, existing technologies for engineering data fail to provide unified support for cross-organizational sharing, modification, approval, version evolution, and behavior auditing, making it difficult to meet the comprehensive requirements of confidentiality, integrity, controllability, and traceability in cross-organizational collaborative manufacturing. Summary of the Invention

[0004] To address the aforementioned issues, this invention proposes a BOM-based method for secure collaborative editing of cross-organizational engineering data. First, based on the BOM structure, engineering data is finely segmented and corresponding data block indexes are established, constructing lightweight index capsules and encrypted data entity blocks. Data entity blocks are retrieved through index capsules, enabling efficient and on-demand sharing of massive amounts of cross-organizational engineering data, avoiding the overhead of full-file transmission and encryption / decryption. Second, a joint approval modification mechanism based on dynamic threshold-based secret sharing is designed to ensure that no single participant can unilaterally tamper with shared data; modification operations must be confirmed by multiple affected parties. Finally, a blockchain-based behavior tracing mechanism is introduced, immutably recording modification requests, multi-party confirmation actions, and key verification factors on the blockchain, forming publicly verifiable modification history evidence, enabling accurate responsibility identification and post-event auditing. This invention can achieve efficient, reliable, and fine-grained multi-party cross-organizational collaborative manufacturing while ensuring the confidentiality of engineering data.

[0005] This invention is a BOM-based method for secure collaborative editing of cross-organizational engineering data. Multiple service provider companies, coordinated by a leading company, access and collaboratively modify encrypted engineering data stored in the cloud. A blockchain-based smart contract mechanism ensures tamper-proof records of modification requests and confirmations, guaranteeing integrity, traceability, and verifiability.

[0006] The proposed solution supports secure, granular, and efficient cross-organizational collaboration among multiple service provider companies (SPCs) in digital manufacturing environments. Engineering data is typically large and highly structured; directly sharing complete data can lead to excessive overhead and unnecessary information exposure. To address this issue, this invention employs... Figure 2 The illustrated method for encapsulating engineering data based on a bill of materials (BOM) combines task-driven index data capsules with independently encrypted data entities, enabling more efficient and secure data sharing.

[0007] In the proposed method, a Leading Company (LC) coordinates collaborative manufacturing projects. For each project, the LC constructs a Bill of Materials (BOM) tree reflecting the hierarchical relationships between assemblies and components. Each node in the BOM tree is encoded using a chameleon hash associated with its data. Leaf nodes represent the smallest indivisible units of data and serve as the smallest granularity for access control and sharing. Instead of encapsulating complete file content, the LC builds cryptographic indexes based on the corresponding BOM tree encodings of the smallest components and packages them as individual granules into a task-driven index data capsule. Each data entity is independently encrypted using a symmetric key under an attribute-based access policy and stored on a semi-trusted cloud server (CS). Thus, the index capsule provides secure references to a set of related data entities without revealing their contents.

[0008] When a Service Provider Company (SPC) is authorized to perform a specific manufacturing task, the Leading Company (LC) issues a corresponding index capsule and decryption token. Using the embedded index within the granules obtained from decrypting the capsule, the SPC can efficiently locate and retrieve the required encrypted data entities from the Cloud Server (CS) without accessing irrelevant data. This index-based sharing mechanism significantly improves retrieval efficiency and scalability in large-scale engineering projects. For data modifications, the method enforces a joint approval mechanism. All affected SPCs must provide cryptographic confirmation before the modification is finalized. The Leading Company (LC) verifies these confirmations and records the modification intent and authorization result on the blockchain via a smart contract. Each update generates a new verification factor, ensuring the chameleon hash value remains constant, thus achieving tamper-proof and verifiable version management.

[0009] By integrating Bill of Materials (BOM)-based engineering data encapsulation, attribute-based encryption, joint approval based on dynamic threshold secret sharing, version control based on chameleon hashing, and blockchain-based behavior traceability, the proposed method enables secure and efficient cross-organizational collaborative manufacturing throughout the engineering data lifecycle.

[0010] Specifically, the proposed method comprises seven stages. First, the TA establishes global parameters and distributes keys based on identity and attributes. Second, the LC generates project-specific cryptographic parameters and constructs a multinomial-based threshold authorization structure. Third, engineering data is partitioned and indexed according to the BOM, encrypted under a fine-grained access policy, and uploaded to the cloud after forming data entities and index capsules. Fourth, the SPC uses tokens issued by the LC to acquire and decrypt capsules, extracts the data entity index, and then retrieves and decrypts the entities. Fifth, the SPC initiates a change request, triggering a blockchain-based multi-party confirmation process. After collecting a sufficient number of valid confirmations, the LC finally determines and uploads the updated entity. Sixth, each data version is uniquely identified by a chameleon hash and version number, supporting verifiable traceability and access to historical versions. Finally, the complete chain of modification actions can be recovered for regulatory accountability. The specific implementation details of the seven stages of the entire scheme are as follows: (i) Initialization: The Trusted Institution (TA) completes the global parameter settings and master key generation. Each participating company registers with the TA. All registered companies jointly form a consortium blockchain and deploy smart contracts.

[0011] In this phase, the Trusted Authority (TA) first completes the global parameter settings and master key generation; then, each participating company registers with the TA, submits its own attribute set, and obtains attribute keys and public-private key pairs; finally, all registered companies jointly form a consortium blockchain and deploy smart contracts.

[0012] (ii) Project initialization: When the collaborative project is launched, the company that launched the collaborative project will act as the leading company LC, and select a group of companies as service providers SPC to participate in the collaboration, and bind the public key of the SPC to a secret sharing structure based on polynomial.

[0013] (III) Data Encryption and Encapsulation: The leading company will transform the engineering drawing set into securely shareable encrypted data entities and lightweight index capsules to complete data encryption and encapsulation.

[0014] This phase is executed by the lead company, and its core task is to transform the complete set of engineering drawings into securely shareable encrypted data entities and lightweight index capsules. First, the lead company establishes a Bill of Materials (BOM) based on project requirements and then finely divides the overall data into independent data blocks according to the BOM. Next, an independent access policy is defined and encrypted for each data block. Then, a chameleon hash value that supports version verification is calculated for each data block, and these blocks are packaged into data entities. Finally, these index granules are encapsulated into index capsules, forming a secure and efficient retrieval portal for massive amounts of data.

[0015] (iv) Data sharing: The data sharing phase includes two processes: data decryption and ciphertext update.

[0016] The data sharing phase is a crucial step in achieving on-demand, fine-grained authorization, encompassing two closely linked processes: data decryption and encrypted updates. When a service provider needs access to specific component drawings, the leading company issues a targeted authorization token and decryption token. The service provider first verifies the authorization and decrypts the index capsule, extracting an index pointing to the target data. It then efficiently retrieves the encrypted data entity from the cloud server using the index. After confirming that its attributes meet the access policy defined on the data block, it decrypts and recovers the original drawing. After access is complete, to ensure forward security and prevent the issued tokens from being reused in the future, the leading company also performs a re-randomization update of the encrypted data in the cloud.

[0017] (v) Joint approval of data modification: When a service provider company reviews the drawings and decides to modify them, the joint approval modification process in this stage is triggered.

[0018] When a service provider company reviews the drawings and decides to modify them, the joint approval modification process at this stage is triggered. The core of this mechanism is that no participating party can unilaterally tamper with shared data, and any modification request must obtain cryptographic confirmation from all other service providers affected by the modification. Specifically, the service provider initiating the modification first encrypts the new data and submits it to the lead company; after review, the lead company notifies all affected parties of the modification intent along with relevant information and publicly records it on the blockchain via a smart contract; after verifying the modification, each affected party generates and submits a cryptographic secret share as proof of consent; only after collecting a sufficient number of valid shares can the lead company reconstruct the chameleon hash private key necessary for modification authorization, thus ultimately completing the update of the encrypted data, generating a verification factor consistent with the new version of the data, and immutably recording the entire modification process on the blockchain. The entire process consists of three steps: preparing and submitting the modification entity, modification notification and multi-party confirmation, and final confirmation of the modification.

[0019] (vi) Multi-version access: Service provider companies are able to perform multi-version access when retrieving data entities.

[0020] Furthermore, service provider companies can perform multi-version access when retrieving data entities, flexibly specifying the target version and independently verifying the legitimacy of the data's source to prevent maliciously forged versions from infiltrating the system. Specifically, when initiating an access request, the service provider company must provide the chameleon hash value of the target data block and the desired version number; if no version number is specified, the system defaults to returning the latest version of the data block. After obtaining the data entity, the service provider company must perform a cryptographic verification: using the publicly available chameleon hash public key, check whether the data content and the attached random number match the identity identifier of the original data block. Only after successful verification can it be confirmed that the data version truly originated from the original data and evolved through a legitimate modification process.

[0021] (vii) Behavior Traceability: Any authorized participant or regulatory auditing body can conduct a complete and compliant review of any collaborative modification process by searching the blockchain. The entry point for traceability is the target component index. Or a specific transaction request .

[0022] Beneficial effects of this invention: This invention proposes a BOM-based cross-organizational engineering data secure collaborative editing method. By organically integrating BOM and index capsule-based sharing technology, dynamic threshold-based secret sharing joint approval technology, and blockchain-based behavior traceability technology, it achieves unified protection of confidentiality, integrity, controllability, and traceability throughout the entire lifecycle of engineering data. This effectively solves the three core problems faced by existing technologies in cross-organizational collaborative manufacturing scenarios: difficulty in fine-grained sharing, uncontrollable modification authorization, and difficulty in defining and tracing operational responsibilities. Specific beneficial effects are as follows.

[0023] By using engineering data sharing technology based on BOM and index capsules, we have achieved efficient, fine-grained, and secure sharing of large-scale engineering data, solving the problems of high overhead, low efficiency, and excessive information exposure in the traditional offline full-file encrypted sharing mode of engineering data.

[0024] This invention creatively combines the hierarchical structure of the Bill of Materials (BOM) with index encapsulation. The leading company divides the complete engineering dataset into independent data blocks based on the BOM tree, defines an independent attribute-based access policy for each data block and encrypts it separately, and simultaneously constructs a path index containing chameleon hash values ​​for each leaf node component along the BOM tree path, encapsulating all indexes into a lightweight index capsule. This design brings three benefits: First, the licensor only needs to decrypt the index capsule to obtain a precise retrieval entry point for the target data, without traversing or downloading the complete massive engineering data, significantly reducing communication and computational overhead; Second, each data block is protected by an independent access policy, achieving true on-demand, fine-grained sharing, with different service provider companies only able to decrypt the subset of data matching their attribute permissions, avoiding excessive exposure of irrelevant information; Third, the index capsule itself is extremely small, and compared to engineering data such as 3D model files that are often hundreds of megabytes in size, its transmission and decryption overhead is almost negligible, demonstrating excellent scalability in collaborative manufacturing scenarios for large-scale complex products.

[0025] By using a joint approval modification technology based on dynamic threshold secret sharing, it ensures that no single participant can unilaterally tamper with the shared data. At the same time, it achieves verifiable version evolution based on chameleon hashing, solving the problems of uncontrolled modification permissions and the trustworthiness of data modified by multiple versions in cross-organizational collaboration scenarios.

[0026] This invention designs a cryptographically enforced multi-party joint approval mechanism. During the project initialization phase, the leading company splits the core secret necessary for modification permissions—the Chameleon Hash private key—into multiple secret shares using a Lagrange interpolation polynomial, and binds these shares to the public keys of each service provider company. Upon any modification request, the leading company automatically identifies all affected participants based on the BOM structure and distributes modification notifications. Each affected party must generate and submit a valid secret share using its own private key as confirmation proof. Only after collecting a sufficient number (reaching a preset threshold) of valid shares can the leading company reconstruct the Chameleon Hash private key, thereby calculating a new verification random number for the new version of the data, completing the ciphertext modification without altering the original data block's identity (i.e., the Chameleon hash value). The effects of this mechanism are as follows: First, it eliminates the possibility of any single company (including the leading company itself) unilaterally tampering with data from a cryptographic perspective. Modification must be collectively authorized by the affected parties, truly achieving multi-party co-governance. Second, the chameleon hash technology ensures that all legitimate modified versions share the same identity identifier, and as the version number increases, service provider companies can independently confirm the same origin relationship between any version and the original data through simple hash verification, realizing the trusted evolution of data versions and anti-counterfeiting traceability.

[0027] By using blockchain-based behavioral traceability technology, the entire collaborative modification process can be recorded and publicly verified in an tamper-proof manner, solving the problems of unauditable operational behaviors and difficulty in defining and tracing responsibilities in cross-organizational collaborative manufacturing.

[0028] This invention features a unified, structured blockchain transaction format (encompassing three types: modification request, confirmation, and final confirmation), anchoring the complete chain of each modification action on the consortium blockchain. The modification request transaction records "who, when, which component, and what modification was initiated"; the confirmation transaction provides non-repudiable evidence, including cryptographic verification factors, of each affected party's consent; and the final confirmation transaction closes the entire process, proving that the final modification was legally completed after meeting the joint approval conditions. These three types of transactions are interconnected, forming a complete and tamper-proof audit trail. The effect is that any authorized participant or regulatory agency can independently search the blockchain to verify the integrity and compliance of any modification, and any subsequent denial or forgery will be easily detected due to the lack of corresponding cryptographic evidence. This provides a solid technical foundation for liability determination, dispute resolution, and compliance auditing in cross-organizational collaborative manufacturing, truly realizing "every action leaves a trace, traces allow for traceability, and traceability allows for accountability." Attached Figure Description

[0029] Figure 1 Schematic diagram of the system model of this invention; Figure 2 Schematic diagram of the data encapsulation method of the present invention; Figure 3 A diagram illustrating the BOM tree structure required to create an index. Detailed Implementation

[0030] The method of this invention relates to the following entities: Trusted Authority (TA): A Trusted Authority (TA) is a fully trusted entity responsible for system initialization and identity management, such as a government agency. Specifically, the TA generates global system parameters and cryptographic keys, and issues public-private key pairs to legitimate participants during the registration phase. It is assumed that the TA is honest and does not participate in routine data operations after the system is established.

[0031] CS (Cloud Server): A cloud server (CS) is a semi-trusted storage provider that offers scalable data storage services. It stores encrypted data entities and supports encrypted retrieval and update operations according to the instructions of the authorized party. While it is assumed that the cloud server follows the prescribed protocols, it is considered "honest but curious," meaning it may attempt to infer sensitive information from the stored data.

[0032] LC (Lead Company): The lead company is responsible for the granular division of engineering data, acts as the coordinator for collaborative projects, and manages access control policies and data modification workflows. It is responsible for segmenting the complete engineering data according to the Bill of Materials (BOM), encrypting and storing the segmented documents, and creating corresponding indexes to package them into capsules. Furthermore, it reviews modification requests, coordinates multi-party confirmation processes, and interacts with smart contracts to record modification intent and authorization results.

[0033] SPC (Service Provider Company): Service Provider Companies possess various attributes, participate in collaborative tasks based on their assigned permissions, and access project data related to their own attributes. Service Provider Companies can decrypt authorized data for legitimate use and initiate data modification requests when necessary. Furthermore, any Service Provider Company affected by modifications initiated by other Service Provider Companies needs to confirm that request.

[0034] Consortium Blockchain and Smart Contracts (SC): A consortium blockchain is maintained by an authorized and trusted company. As a decentralized, tamper-proof ledger, it records key events such as authorization agreements, modification notifications, modification records, and verification parameters. Smart contracts deployed on the blockchain enforce access control logic, automatically distribute notifications, and provide public verifiability for multi-party confirmation processes.

[0035] To clearly illustrate the workflow of the proposed BOM-based cross-organizational engineering data secure collaborative editing method in digital manufacturing for processing engineering data, such as... Figure 1 and Figure 2As shown, taking engineering drawings as an example, the specific implementation details of the entire solution in seven stages are as follows: (a) Initialization In this phase, the Trusted Institution (TA) first completes the global parameter settings and master key generation; then, each participating company registers with the TA, submits its own attribute set, and obtains attribute keys and public-private key pairs; finally, all registered companies jointly establish a consortium blockchain and deploy smart contracts. The specific process is as follows: 1. Trusted Authority (TA) Initialization TA runs the initialization algorithm. First, it determines the global scope of the attributes. And generate bilinear group parameters: select a large prime number. ,structure Cyclic group and target group , They are Bilinear mapping It is a special pairing function that pairs the group Elements and groups The elements in the array are matched one by one, and the result falls into the group. , recorded as Then, the method defines several hash functions used in the process: Mapping bit strings of arbitrary length to modulo Non-zero integer field , Map any string to a group middle; Will Elements in the model are mapped to the modulo Non-zero integer field ; Will The elements in the map are mapped to a fixed length. The bit string. TA randomly selects a random number. As the system's master private key And calculate the master public key. TA kept it secret. Publicly disclosed parameters And all hash functions.

[0036] 2. Company Registration After completing the global initialization, companies intending to participate in the collaboration will obtain the publicly available parameters. Initiate registration with TA. The company first selects a random number. Using identity tokens and calculate ( (This represents string concatenation) and calculates the intermediate value. The company will and its corresponding set of attributes (For example: cloud computing services, large enterprises, private enterprises, listed companies) Submit to TA. TA will then verify the information. It is a global attribute A subset of the data, and then a random number is selected for the company. ∈ Calculation formula = This serves as the company's public key. Then, TA selects a random number. ∈ ,against For each attribute s in the dataset, calculate the attribute key component: , The company's complete attribute key was finally obtained as follows TA will , and Securely sent to the corresponding company. Upon receipt, the company utilizes... Calculate your own private key = · , and save , and TA then registered the company locally. and The corresponding relationship is established to complete the registration; when Not a global attribute A subset of that subset will not be registered. 3. Establishment of a consortium blockchain After all participating companies complete their registration, they collectively form a consortium blockchain network. Each company joins as an authorized node on the consortium blockchain, deploying smart contracts for subsequent collaborative modification processes. The smart contracts pre-define processing logic for three types of transactions: modification requests, confirmations, and final confirmations, and bind each participating company's public key as the basis for signature verification. At this point, an immutable and jointly maintained infrastructure for recording behavior by trusted participants is complete, providing publicly verifiable on-chain support for joint approval and data traceability in all subsequent projects. (II) Project Initialization After system initialization is complete, when each collaborative project is launched, the leading company (LC) that initiated the project first generates dedicated cryptographic parameters for the project. Next, it selects a group of companies as participating service provider companies (SPCs) and binds their public keys to a polynomial-based secret sharing structure, laying the foundation for subsequent joint approval mechanisms. The specific process is as follows.

[0037] 1. Parameter settings for the leading company (LC) Leading company (LC), select two prime numbers. And calculate the product ,as well as Euler's totient function value The private key of the leading company must be guaranteed. and If the numbers are coprime, then a new prime number should be chosen. Then select with Coprime integers And calculate the conditions that are met. integers Define a hash function Mapping bit strings of arbitrary length to modulo Non-zero integer field Finally, generate the Chameleon hash key pair: public key and private key Finally, the leading company selected one larger than... prime numbers This is used for subsequent polynomial construction. At this point, the leading company has completed the setting of project-level cryptographic parameters and publicly released the Chameleon Hash public key.

[0038] 2. Select a Service Provider Company (SPC) and construct a licensing polynomial. After completing the parameter settings, the leading company publishes the project requirements and selects from all registered companies. A number of eligible service provider companies. Each of these selected companies provides its public key. The leading company uses its private key to perform an elliptic curve multiplication with each service provider's public key to obtain a set of point coordinates. To construct a secret structure requiring multi-party authorization for reconstruction, the leading company began constructing interpolation points. The first point was set as... Subsequent points are generated using the public keys of each service provider: for each service provider, calculate... As the x-coordinate of the point, and the corresponding These points serve as the y-coordinates of the points. Using these points, the leading company constructs a model using Lagrange interpolation. Polynomial in the sense of Finally, the company that led the effort destroyed the original secrets. It only stores polynomial coefficients. and prime numbers The public key of the public chameleon hash is public. At this point, an authorization structure bound to multiple identities has been established, providing a cryptographic foundation for joint approval of subsequent data modifications.

[0039] (III) Data Encryption and Encapsulation This phase is executed by the lead company, and its core task is to transform the complete set of engineering drawings into securely shareable encrypted data entities and lightweight index capsules. First, the lead company establishes a Bill of Materials (BOM) based on project requirements and then finely divides the overall data into independent data blocks according to the BOM. Next, an independent access policy is defined for each data block and encrypted. Then, a chameleon hash value that supports version verification is calculated for each data block, and these blocks are packaged into data entities. Finally, these index granules are encapsulated into index capsules, forming a secure and efficient retrieval portal for massive amounts of data. The specific steps are as follows.

[0040] 1. Encrypted data entities After obtaining the publicly available system parameters, the leading company began processing each data block. Based on the bill of materials, the complete engineering data had been divided into representative assembly drawings ( ), Subassembly drawing ( ) and part drawings ( Multiple data blocks of different types, denoted as For each data block, the leading company first tailors an access policy specifically for that data block. This strategy defines which set of attributes a company can decrypt the data block. The access strategy uses a Boolean formula, and any Boolean formula can be transformed into a polynomial-time expression. ,in It is OK A matrix of columns, where each row corresponds to an attribute condition, and is mapped using a function. To associate line numbers with specific attribute names, define the following symbols: ,as well as ,express The maximum number of times the same attribute can be used, where express All values. Also, initialize a version number. The value is 0. Next, the leading company performs the encryption operation. It selects a random secret value. and random vectors , ,calculate ,for ,calculate , Represents a random vector The first in Each element, for ,calculate Then calculate the symmetric key. Then use that key. The original data block is symmetrically encrypted using AES to obtain the ciphertext. The leading company then performed mask calculations. ,in It is a random binary mask of equal length. This represents the XOR operation. Finally, the leading company selects a random number. ,calculate: Get the chameleon hash value , Indicates the data block type, which can be... , and At this point, a complete data block entity is formed. Once constructed, different types of data block entities are represented as follows: = The leading company eventually uploaded all data block entities to the cloud server.

[0041] 2. Encapsulating index capsules After encrypting and uploading all data entities, the leading company began building a retrieval portal, the index capsule, to enable efficient, on-demand retrieval of massive amounts of encrypted data. The process of building the index capsule was based on a Bill of Materials (BOM) tree reflecting the product assembly relationships, such as... Figure 3 As shown, this tree was constructed by the leading company based on the product assembly relationships in the bill of materials. In the diagram, part drawing C and part drawing A are associated with assembly drawing E; assembly drawing E and part drawing B are associated with assembly drawing B; part drawing C and part drawing D are associated with assembly drawing D; part drawing A, assembly drawing B, and assembly drawing D are associated with assembly drawing A; part drawing B is associated with assembly drawing C; and assembly drawing A, assembly drawing C, and part drawing A are associated with final assembly drawing A.

[0042] In a BOM tree, leaf nodes typically represent the most basic part drawings, while intermediate and root nodes represent sub-assembly drawings and final assembly drawings. The leading company starts from the top-level final assembly drawing and works down the BOM tree to each individual part. Generate a unique index granule. Specifically, this is done by... Collect the chameleon hashes of all data blocks corresponding to all nodes along the complete path from the root node to it. .For example Figure 3 As shown in the assembly drawing Departure, via subassembly and Finally, the parts are reached. Then the path is represented as a hash chain. ,Component The index is represented as: The final index of the part obtained by the above method. It is defined as: the hash value of the root node, plus the set of all possible paths to the part, plus the hash value of the part itself. Expressed as a formula: = {The set of all paths}. If the same part is used in multiple different locations within a product, then its multiple paths will be combined into a union within {}, without creating multiple indexes.

[0043] this This constitutes an index particle. When all the index particles of the parts... Once all the data is generated, the leading company will define an overall access strategy for the entire index capsule. This strategy controls who has access to the capsule containing the data index. Then, by running the data capsule encapsulation algorithm, all these index particles and access strategies are processed together to ultimately generate a unique index capsule. and its identifier At the same time, a secret parameter is generated for subsequent decryption and verification. L .

[0044] Ultimately, the index capsule The data was also uploaded to the cloud server. The mask and index granules used for encryption, however, were stored locally by the leading company. At this point, the encryption and encapsulation of the data blocks were complete.

[0045] (iv) Data sharing The data sharing phase is a crucial step in achieving on-demand, fine-grained authorization, encompassing two closely linked processes: data decryption and encrypted update. When a service provider needs access to specific component drawings, the leading company issues a targeted authorization token and decryption token. The service provider first verifies the authorization and decrypts the index capsule, extracting the index pointing to the target data. Then, it efficiently retrieves the encrypted data entity from the cloud server using the index. After confirming that its attributes meet the access policy defined on the data block, it decrypts and recovers the original drawing. After access is complete, to ensure forward security and prevent the issued tokens from being reused in the future, the leading company also re-randomizes and updates the encrypted data in the cloud. The specific process is as follows.

[0046] 1. Data Decryption The service provider company needs access to a certain part When requesting relevant drawings, a request is sent to the lead company. Upon receiving the request, the lead company confirms the request's authorization and then generates a set of authorization credentials for this task. This set of credentials includes a task token. Index capsule identifier and download token Among them, task tokens and download token It is a temporary credential used for subsequent verification and decryption operations. This is used to locate the corresponding index capsule on the cloud server. Simultaneously, it is used for all types of drawings associated with this part (potentially including its corresponding assembly drawings). Subassembly drawing and parts drawings (Itself), the leading company will use the mask previously used for encryption. As a decryption token, it is securely sent to the service provider company.

[0047] The service provider company first utilizes the received Locate and download the corresponding index capsule from the cloud server. Next, the service provider company uses its own attribute key and download token. The decryption algorithm is then invoked to decrypt the index capsule. Upon successful decryption, the service provider company will receive the index particle corresponding to that part. .

[0048] This index granule is essentially a navigation map: it contains the chameleon hash value of the root node, the set of chameleon hash values ​​involved in all component paths leading to that part, and the chameleon hash value of the part's data block itself. The service provider uses all the chameleon hash values ​​recorded in the index granule as search keywords to initiate a query to the cloud server, accurately retrieving all corresponding data entities. . (One of them) Type of data entity For example: = .

[0049] After obtaining the data entity, the service provider company first calculates the original ciphertext. ,verify Next, access control verification and decryption are performed. The service provider company checks whether its own attribute set meets the access policy defined in the data entity. If the set of attributes satisfies this strategy, then a set of constants can be found mathematically. This ensures that a linear combination of these constants and the corresponding row's access strategy matrix vector results in a vector of (1, 0, …, 0). Using this set of constants and its own attribute key… The service provider can perform a bilinear pairing operation on the individual components in the data and the ciphertext components in the data entity to recover the symmetric encryption key. : Ultimately, the service provider company used the recovered For encrypted data Perform AES symmetric decryption to obtain the original plaintext drawings. If the service provider only needs to view the drawings without making any modifications, the process ends here, and a confirmation message is returned to the leading company.

[0050] 2. Update ciphertext To ensure forward security—that is, to guarantee that the token used for this authorization becomes invalid after the task is completed, and to prevent the old decryption token from being maliciously reused to decrypt updated ciphertext—the leading company will update the ciphertext stored on the cloud server after each data access and confirmation. Specifically, the leading company generates a new random mask locally. ', used to replace the old mask Then, it calculates an update token. , The value is the XOR result of the old and new masks, that is... = '⊕ .this It itself does not contain any plaintext information, but possessing it allows one to convert ciphertext protected by the old mask into ciphertext protected by the new mask. The leading company will... Send to the cloud server. The cloud server receives the update token. Then, the masked ciphertext in the stored data entity. Perform a simple XOR operation to obtain the new ciphertext. = ⊕ In this way, the cloud server, completely unaware of the plaintext data content, updates the ciphertext to a new form that can only be recovered using the new mask. After the update, the old mask... Immediately invalidated. Meanwhile, the leading company used it locally. 'Cover the original This completes the update of the local state. At this point, the entire data sharing process is finished, fulfilling both the data delivery to the authorized party and ensuring forward security for future access to the system.

[0051] (v) Data modification under joint approval When a service provider company reviews the drawings and decides to modify them, the joint approval modification process at this stage is triggered. The core of this mechanism is that no participating party can unilaterally tamper with shared data, and any modification request must obtain cryptographic confirmation from all other service providers affected by the modification. Specifically, the service provider initiating the modification first encrypts the new data and submits it to the lead company; after review, the lead company notifies all affected parties of the modification intent along with relevant information and publicly records it on the blockchain via a smart contract; after verifying the modification, each affected party generates and submits a cryptographic secret share as proof of consent; only after collecting a sufficient number of valid shares can the lead company reconstruct the chameleon hash private key necessary for modification authorization, thus ultimately completing the update of the encrypted data, generating a verification factor consistent with the new version of the data, and immutably recording the entire modification process on the blockchain. The entire process consists of three steps: preparing and submitting the modification entity, modification notification and multi-party confirmation, and final confirmation of the modification.

[0052] 1. Entities for preparing and submitting modifications The service provider company decrypted and viewed a certain drawing. Subsequently, it was decided to modify it. The service provider company first revised the drawing data locally, generating the modified data. To ensure the confidentiality of the changes during the submission process, service provider company A randomly selects a new symmetric key. Using the AES symmetric encryption algorithm to Encryption is performed to obtain the modified ciphertext. Subsequently, the service provider company used the public key of the leading company to... Encryption is performed to obtain the encrypted key. This ensures that only the lead company can decrypt and view the modified content. Next, service provider company A packages the modified ciphertext data with the unchanged cryptographic components from the original data entity, constructing a modified entity to be submitted. : = Finally, service provider company A will modify this entity. Along with the encrypted symmetric key One's own identity marker Data entity index and a summary of the modifications described in plain text. (Record which non-confidential process parameters or changes were modified) and submit them to the lead company.

[0053] 2. Modification Notification and Confirmation After receiving the modification request, the leading company first verifies the version number in the data entity. This checks if the request matches the original request to prevent replaying modification requests from older versions. Once verified, the leading company decrypts the request using its own private key. get Then decryption Obtain the modified plaintext data The lead company conducts a compliance review of the modifications. Once confirmed to be correct, based on the Bill of Materials (BOM) tree structure, it analyzes which service provider companies' components will be affected by the modifications, thus determining the set of affected parties. Assuming there are a total of [number missing] parties... One affected party.

[0054] This method uniquely defines the blockchain transaction format, for each transaction... It is a tuple: ,in: It is a globally unique transaction identifier. This indicates the transaction type, corresponding to modification request, confirmation, and final confirmation, respectively. It is the public key address of the transaction publisher. This contains detailed information about the transaction. yes The set of public key addresses of authorized decryptors of the encrypted text. Indicates the time the transaction was submitted. It is the transaction publisher's Digital signature.

[0055] All transactions are submitted via smart contract calls, and the smart contract verifies the signature and... It is stored immutably on the blockchain. This unified format ensures public auditability and non-repudiation, allowing any authorized participant or auditing firm to retrieve and verify the complete sequence of events for any data modification.

[0056] Subsequently, the leading company used the public key of each affected service provider company i to access information containing data entity indexes and modification summaries. Encryption is performed to generate a set of ciphertext notifications. Each affected party can only decrypt their own notification using their own private key. Next, the leading company sends a transaction of type "..." to the smart contract deployed on the consortium blockchain. (i.e., modification request) signed transaction Details of this transaction It includes the identity of the service provider company that initiated the modification, as well as all encrypted notifications sent to the affected parties. After the smart contract verifies the signature of the leading company, it records the transaction immutably on the blockchain and broadcasts it to the entire network.

[0057] Each service provider company is continuously monitoring new transactions generated on the blockchain. When a service provider company discovers a transaction... When the set of public key addresses of the authorized decryptor of a transaction contains its own public key, it extracts its own encrypted notification from that set. Decrypt using your own private key to obtain ( It is based on The modifications described herein should be assessed to evaluate their potential impact on the components under your responsibility.

[0058] If the modification is agreed upon, the service provider company i needs to generate a cryptographic secret share. As proof of consent, the generation mechanism of this share is closely related to the polynomial authorization structure built during the project initialization phase. Specifically, it uses its own private key and the public key of the leading company to calculate the coordinates of a point through elliptic curve dot product. Next, it selects a random number. Calculate a validation factor Then, it uses the public key of the leading company. Shares Encryption is performed to obtain the encrypted share. It will Send to the leading company, and simultaneously submit a transaction of type " (i.e., confirmation) of a signed transaction The transaction It contains the confirmed original request transaction number. one's own identity Encrypted target data entity index, random number and verification factors The public record of this transaction constitutes irrefutable cryptographic evidence that the service provider company agreed to the modification.

[0059] 1. Final confirmation of the modifications The leading company receives and collects encrypted shares from various affected service provider companies. Once the number of shares collected reaches a preset threshold t', it is considered that the modification has obtained sufficient joint authorization from relevant parties, and the leading company can then initiate the final ciphertext modification process.

[0060] First, the leading company needs to verify the validity and freshness of each received secret share. For each share, it downloads the corresponding confirmation transaction from the blockchain. Extract the publicly available random numbers. and validation factor Decrypt using your own private key Restore the share of the explicit Then, a two-step verification is performed: the first step is real-time verification, which involves checking the equation. To determine if the condition is met, the first step is to ensure that the share is the most recently generated share and not a replayed old share. The second step is to verify correctness by using a bilinear mapping to check the equation. Does this hold true? Due to the properties of bilinear mappings, if... If the equation is indeed correctly calculated by service provider company i using its private key and the leading company's public key, then the equation must hold true. Through these two verification steps, the leading company is convinced that the share is genuine, valid, and comes from the correct participant.

[0061] Once all t' valid shares have been collected, the leading company begins to reconstruct the protected core secret: the private key to the Chameleon Hash. The leading company utilizes each effective share in conjunction with polynomial coefficients generated by the leading company itself during the project initialization phase. Calculate the corresponding y-coordinate value This yields a set of pure interpolation points ( , Using this point t', the leading company reconstructs the polynomial g(x) of degree t'-1 through Lagrange interpolation. The constant term g(0) of this polynomial is the chameleon hash private key that is secretly shared and protected. .

[0062] Recover Subsequently, the leading company gained the authority to calculate new random numbers for the modified data without altering the original data block's chameleon hash value. The leading company first used the original data block's access policy to re-execute the standard encryption process during the data encryption phase, using the original symmetric key. For the modified data Encryption is performed to obtain new ciphertext. Next, it generates a new random mask. XOR masking of the new ciphertext yields... ' = ⊕ Then, it uses the private key that was just recovered. Find a new random number for this new ciphertext. This ensures that the chameleon hash value remains unchanged, i.e., satisfies the equation. Here, because the controlling company possesses the private key d, this search process is computationally feasible, which is the core characteristic of Chameleon Hash. Thus, the updated data entity is: = The build is complete. The lead company uploads the new entity to the cloud server. Simultaneously, the new decryption mask is securely stored locally. Update version number records.

[0063] Finally, the leading company submitted a transaction of type " (i.e., final confirmation) A transaction with a signature. The transaction It contains the original modification request transaction number. A set of all confirmed transaction numbers The encrypted target component index and the new version number are recorded. After the smart contract verifies the signature, it records the transaction on the blockchain. The existence of this transaction publicly proves to all participants and auditors that this modification to the component was legally completed by the leading company after meeting the joint approval conditions and collecting sufficient valid confirmations. The entire joint approval data modification process is now complete.

[0064] (vi) Access to multiple versions Furthermore, service provider companies can perform multi-version access when retrieving data entities, flexibly specifying the target version and independently verifying the legitimacy of the data's source to prevent maliciously forged versions from infiltrating the system. Specifically, when initiating an access request, the service provider company must provide the chameleon hash value of the target data block and the desired version number; if no version number is specified, the system defaults to returning the latest version of the data block. After obtaining the data entity, the service provider company must perform a cryptographic verification: using the publicly available chameleon hash public key, check whether the data content and the attached random number match the identity identifier of the original data block. Only after successful verification can it be confirmed that the data version truly originated from the original data and evolved through a legitimate modification process. The specific process is as follows.

[0065] When a service provider needs to access the relevant drawings of a certain part, following the process described in the data sharing phase, it first obtains and decrypts the index capsule. The relevant index particles for the part are then extracted from this data. Each index particle records the chameleon hash values ​​of the data blocks associated with the part. This hash value serves as a unique identifier for the data block throughout its entire lifecycle and remains unchanged after the data is initially encapsulated. Service provider companies use... A retrieval request is initiated to the cloud server using the target identifier. An optional version number can be specified during the request. Specify the specific version required, for example, to rewind and view the design state of a historical version. If only the version number is provided in the request... If no version number is specified, the cloud server will default to returning that it has the version number. Identifier and version number The data entity with the largest value is the latest valid version.

[0066] The cloud server returns the corresponding data entity based on the request. Subsequently, the service provider company conducted a version validity verification. The core of the verification was to confirm that the data content contained in the data entity, although it may have been modified multiple times, did indeed originate from the original data using the chameleon hash value. The original data block is identified, not a version that has been maliciously replaced or fabricated by an attacker.

[0067] The specific verification steps are as follows: The service provider company first uses a decryption token (i.e., a random mask) obtained from the leading company that corresponds to the current version number. ), masked ciphertext in data entities Perform an XOR operation to recover the intermediate ciphertext. = ⊕ Next, it extracts the current random number attached to the data entity. The Chameleon Hash public key disclosed during the project initialization phase and the original chameleon hash value obtained from the index. Verify whether the following equation holds true: If the equation holds true, the verification passes, indicating that the data entity is either the original data entity or the person who possesses the private key. The derivative version was created by the legitimate leading company after obtaining joint approval from multiple parties and modifying the original data.

[0068] (vii) Behavioral tracing Any authorized participant or regulatory auditing body can conduct a complete and compliant review of any collaborative modification process by searching the blockchain. The entry point for traceability is the target component index. Or a specific transaction request .

[0069] First, the auditors used the target component index as a guide to retrieve all modification request transactions related to that component from the blockchain. Every stroke The transaction clearly records: which service provider company (identified by its public key) and when ( The system initiated a modification request, along with the list of public keys of the notified parties involved in the request—that is, the list of authorized decryption public keys in the transaction. Auditors can verify this. The signature confirms that the request was indeed submitted by the party claiming to have initiated it.

[0070] For a specific The transaction, the auditor uses its Using the association condition, retrieve all types that are " (Confirmed) transaction set { }. Each stroke The transaction records the confirmer's public key and the cryptographic verification factor provided by that party. and random numbers And the confirmed original request transaction number. These transactions serve as irrefutable cryptographic evidence that the listed notified parties did indeed receive the modification notification, perform the verification, and give their consent. By verifying each transaction... The signature confirms that these confirmation actions are genuine and not forged.

[0071] Then, the auditor's search type was " (Final confirmation) transaction The transaction was based on the original of and all related of The collection serves as an index, recording the fact that the leading company has confirmed that the modifications have met the joint approval conditions and have been completed. It also includes the updated version number. This allows auditors to further request the actual data entity of that version from the cloud server for cross-validation.

[0072] By linking these three types of transactions, the entire lifecycle of collaborative modification is completely restructured: This proves the initiation of the intention to modify; Each entry in the table independently proves that the corresponding affected party was aware of and agreed to the modification; This serves as final closure evidence, proving that the modification was legally executed by the leading company after collecting a sufficient number of valid confirmations. This transaction-by-transaction, interlocking chain design ensures that no single party can subsequently deny their actions, and any malicious tampering or unauthorized modification of data will be quickly detected due to the inability to provide a complete chain of confirmations. This provides a solid technical foundation for determining liability and resolving disputes in cross-organizational collaborative manufacturing.

Claims

1. A cross-organizational collaborative editing method for engineering data based on BOM, characterized in that, Includes the following steps S1: The trusted institution TA completes the global parameter settings and master key generation. Each participating company registers with TA. All registered companies jointly form a consortium blockchain and deploy smart contracts. S2: When a collaborative project is launched, the company that launches the collaborative project acts as the lead company (LC) and selects a group of companies as service providers (SPCs) to participate in the collaboration. The public key of the SPC is then bound to a secret sharing structure based on a polynomial. S3: The leading company transforms the engineering drawing set into securely shareable encrypted data entities and lightweight index capsules, completing data encryption and encapsulation; S4: The data sharing phase includes two processes: data decryption and ciphertext update. S5: When a service provider reviews the drawings and decides to modify them, the joint approval modification process in this stage is triggered. S6: Service provider companies are able to perform multi-version access and trace behavior when retrieving data entities.

2. The method for secure collaborative editing of cross-organizational engineering data based on BOM according to claim 1, characterized in that, The specific implementation process of step S1 is as follows: Global initialization: First, the Trusted Authority (TA) determines the global attribute scope. And generate bilinear group parameters: select a prime number. ,structure Cyclic group and target group , They are Bilinear mapping group Elements and groups The elements in the array are matched one by one, and the result falls into the group. , recorded as Then, the following hash functions are defined: Mapping bit strings of arbitrary length to modulo Non-zero integer field , Map any string to a group middle; Will Elements in the model are mapped to the modulo Non-zero integer field ; Will The elements in the map are mapped to a fixed length. The bit string; TA randomly selects a random number As the system's master private key And calculate the master public key. ; TA keeps secret Publicly disclosed parameters And all hash functions; Company Registration: After completing global initialization, companies intending to participate in the collaboration obtain public parameters. Initiate registration with TA; the company first selects a random number. Using identity tokens and calculate , This indicates string concatenation and calculates the intermediate value. The company will and its corresponding set of attributes Submit to TA; After TA receives it, when It is a global attribute A subset of the data, and then a random number is selected for the company. ∈ Calculation formula = This serves as the company's public key; then TA selects a random number. ∈ ,against For each attribute s in the dataset, calculate the attribute key component: ； ； The company's complete attribute key was finally obtained as follows TA will , and Securely sent to the corresponding company; upon receipt, the company utilizes... Calculate your own private key = · , and save , and ; TA then registered the company locally. and The corresponding relationship is established to complete the registration; when Not a global attribute A subset of [a subset of a ... Consortium Blockchain Setup: After all participating companies complete their registration, all registered companies jointly establish a consortium blockchain network. Each company joins as an authorized node of the consortium blockchain and deploys smart contracts for subsequent collaborative modification processes. The smart contracts pre-define the processing logic for three types of transactions: modification requests, confirmations, and final confirmations, and bind the public keys of each participating company as the basis for signature verification.

3. The method for secure collaborative editing of cross-organizational engineering data based on BOM according to claim 2, characterized in that, The specific implementation process of step S2 is as follows: Leading Company (LC) Parameter Settings: The company that initiated the collaborative project serves as the leading company (LC). The leading company (LC) is selected from two prime numbers. And calculate the product ,as well as Euler's totient function value Safeguard the private key of the leading company and If the numbers are coprime, then a new prime number should be chosen. Then select with Coprime integers And calculate the conditions that are met. integers Define a hash function Mapping bit strings of arbitrary length to modulo Non-zero integer field Finally, generate the chameleon hash key pair: public key and private key Finally, the leading company selected a larger... prime numbers This is used for subsequent polynomial construction. At this point, the leading company has completed the setting of project-level cryptographic parameters and publicly disclosed the Chameleon Hash public key. Select a Service Provider Company (SPC) and build the licensing polynomial: After completing the parameter settings, the lead company publishes the project requirements and selects from all registered companies. A number of eligible service provider companies; each selected company provides its public key. The leading company uses its private key to perform an elliptic curve multiplication with each service provider's public key to obtain a set of point coordinates. The leading company began constructing interpolation points: the first point was set as follows: Subsequent points are generated using the public keys of each service provider: for each service provider, calculate... As the x-coordinate of the point, and the corresponding As the y-coordinate of the point; Using these points, the leading company constructs a polynomial using Lagrange interpolation. Finally, the leading company destroyed the original secrets. It only stores polynomial coefficients. and prime numbers The public key of the public chameleon hash .

4. The method for secure collaborative editing of cross-organizational engineering data based on BOM according to claim 3, characterized in that, The specific implementation process of step S3 is as follows: Encrypted data entities: The leading company divides the engineering data into representative assembly drawings based on the bill of materials. Subassembly drawing and parts drawings Multiple data blocks of different types, denoted as For each data block, the leading company first customizes an access policy for that data block. Access policy Define which set of attributes allows a company to decrypt the data block; the access strategy uses a Boolean formula, and any Boolean formula can be transformed into a polynomial-time expression. ,in It is OK A matrix of columns, where each row corresponds to an attribute condition, and is mapped using a function. The parentheses associate line numbers with specific attribute names, defining the following symbols: ,as well as ,express The maximum number of times the same attribute can be used, where express All values; at the same time, initialize a version number. The value is 0; then, the leading company performs an encryption operation, selecting a random secret value. and random vectors , ,calculate ,for ,calculate , Represents a random vector The first in Each element, for ,calculate Then calculate the symmetric key. Then use the key The data block is encrypted using AES symmetric encryption to obtain the ciphertext. ; The leading company then performed mask calculations. ,in It is a random binary mask of equal length. This represents the XOR operation; finally, the leading company selects a random number. ,calculate: Get the chameleon hash value , This indicates the data block type; at this point, a complete data block entity is represented. Once constructed, different types of data block entities are represented as follows: = The leading company ultimately uploaded all data block entities to the cloud server; Encapsulation of Index Capsules: After encrypting and uploading all data entities, the leading company begins to build a retrieval entry point, namely the index capsule, to enable retrieval of encrypted data. The process of building the index capsule is based on the Bill of Materials (BOM) tree that reflects the product assembly relationship. This tree is built by the leading company based on the product assembly relationship in the BOM. In a BOM tree, leaf nodes represent the most basic part drawings, while intermediate and root nodes represent sub-assembly drawings and final assembly drawings. The leading company starts from the top-level final assembly drawing and works down the BOM tree to each individual part. Generate a unique index granule: for Collect the chameleon hash values ​​of the data blocks corresponding to all nodes along the complete path from the root node to it. Final index of the part It is defined as: the hash value of the root node, plus the set of all possible paths to the part, plus the hash value of the part itself; if the same part is used in multiple different locations of the product, the multiple paths are included in the union of all path sets, and multiple indexes are not created. Forming an index particle, when all parts' index particles Once all the data is generated, the leading company defines an overall access strategy for the entire index capsule. This strategy controls who has access to the capsule containing the data index; subsequently, by running the data capsule encapsulation algorithm, all index particles and access policies are processed together to ultimately generate a unique index capsule. and its identifier At the same time, a secret parameter is generated for subsequent decryption and verification. L ; Ultimately, the index capsule The data was also uploaded to the cloud server, while the mask and index granules used for encryption were stored locally by the leading company. At this point, the encryption and encapsulation of the data blocks were completed.

5. The method for secure collaborative editing of cross-organizational engineering data based on BOM according to claim 4, characterized in that, The specific implementation process of step S4 is as follows: Data Decryption: Service Provider Company Needs Access to a Certain Part When you need the relevant drawings, submit a request to the leading company. Upon receiving the request, the lead company confirmed the user's permissions and then generated a set of authorization credentials for the task; this set of credentials included a task token. Index capsule identifier and download token Meanwhile, for all types of drawings associated with this part, the leading company removed the mask previously used for encryption. This is sent along with the decryption token to the service provider company. The service provider company first utilizes the received Locate and download the corresponding index capsule from the cloud server. Next, the service provider company uses its own attribute key and download token. The data capsule decryption algorithm is invoked to decrypt the index capsule; upon successful decryption, the service provider company will obtain the index particle corresponding to that part. ; The service provider company uses all the chameleon hash values ​​recorded in the index particles as search keywords to launch a query to the cloud server and retrieve all the corresponding data entities. ; After obtaining the data entity, the service provider company first calculates the original ciphertext. ,verify ; Next, access control verification and decryption are performed. The service provider company checks whether its own attribute set meets the access policy defined in the data entity. If the set of attributes satisfies this strategy, then a set of constants is mathematically found. This ensures that a linear combination of these constants and the corresponding row's access strategy matrix vector results in a vector of (1, 0, …, 0); using this set of constants and its own attribute key... The service provider performs a bilinear pairing operation on each component in the data and the ciphertext component in the data entity to recover the symmetric encryption key. : Ultimately, the service provider company used the recovered For encrypted data Perform AES symmetric decryption to obtain the original plaintext drawing; Update the ciphertext: After each data access and confirmation, the leading company updates the ciphertext stored on the cloud server. Specifically, the leading company generates a new random mask locally. ', calculate an update token , The value is the XOR result of the old and new masks, and the leading company will... Send to the cloud server, the cloud server receives the update token Then, the masked ciphertext in the stored data entity. Perform a simple XOR operation to obtain the new ciphertext. After the update, the old mask Immediately invalidated, while the leading company used it locally. 'Cover the original Once the local status update is complete, the entire data sharing process ends.

6. The method for secure collaborative editing of cross-organizational engineering data based on BOM according to claim 5, characterized in that, The specific implementation process of step S5 is as follows: S5.1: The service provider company decrypts and views the drawings. Subsequently, it was decided to modify it; the service provider company first revised the drawing data locally, generating the modified data. The service provider company randomly selects a new symmetric key. Using the AES symmetric encryption algorithm to Encryption is performed to obtain the modified ciphertext. Subsequently, the service provider company used the public key of the leading company to... Encryption is performed to obtain the encrypted key. Next, the service provider packages the modified ciphertext data with the unchanged cryptographic components from the original data entity to construct a modified entity to be submitted. ; = Finally, the service provider company will modify this entity. Along with the encrypted symmetric key One's own identity marker Data entity index and a summary of the modifications described in plain text. Submitted to the lead company; S5.2: After receiving the modification request, the leading company first verifies the version number in the data entity. After verifying that the information matches the access request, the leading company decrypts the data using its own private key. get Then decryption Obtain the modified plaintext data The lead company conducts a compliance review of the modifications. Once confirmed to be correct, based on the structure of the Bill of Materials (BOM) tree, it analyzes which service provider companies' components will be affected by the modifications, thus determining the set of affected parties. Assuming there are a total of... One affected party; Define the blockchain transaction format, each transaction It is a tuple: ,in It is a globally unique transaction identifier. Indicate the transaction type, corresponding to Modify Request, Confirmation, and Final Confirmation, respectively. It is the public key address of the transaction publisher. This is the transaction details. yes The set of public key addresses of authorized decryptors of the encrypted text. Indicates the time the transaction was submitted. It is the transaction publisher's Digital signature; All transactions are submitted via smart contract calls, and the smart contract verifies the signature and... It is stored immutably on the blockchain; The leading company uses the public key of each affected service provider to access information containing data entity indexes and modification summaries. Encryption is performed to generate a set of ciphertext notifications. Each affected party can only decrypt their own notification using their own private key; next, the leading company sends a request to modify a signed transaction to the smart contract deployed on the consortium blockchain. ;Details of this transaction This includes the identity of the service provider company that initiated the modification, as well as all encrypted notifications sent to the affected parties. After the smart contract verifies the signature of the leading company, it records the transaction immutably on the blockchain and broadcasts it to the entire network. Each service provider company is constantly monitoring new transactions generated on the blockchain; when a service provider company discovers a transaction... When the set of public key addresses of the authorized decryptor of a transaction contains its own public key, it extracts its own encrypted notification from that set. Decrypt using your own private key to obtain ( It is based on Assess the potential impact of the modifications described herein on the components you are responsible for. If the modification is agreed upon, the service provider company will generate a cryptographic secret share. As a certificate of consent, specifically, it uses its own private key and the public key of the controlling company to calculate the coordinates of a point through elliptic curve dot product. Next, select a random number. Calculate a validation factor Then, the service provider company uses the public key of the leading company. Shares Encryption is performed to obtain the encrypted share. ;Will Send it to the leading company, and simultaneously submit a signed confirmation transaction to the smart contract. The transaction It contains the confirmed original request transaction number. one's own identity Encrypted target data entity index, random number and verification factors The public record of this transaction constitutes irrefutable cryptographic evidence that the service provider company agreed to the modification. S5.3: The leading company receives and collects encrypted shares from the various affected service provider companies. Once the number of shares collected reaches the preset threshold t', it is considered that the modification has obtained sufficient joint authorization from relevant parties, and the leading company will then initiate the final ciphertext modification work. First, the leading company needs to verify the validity and freshness of each received secret share; for each share, it downloads the corresponding confirmation transaction from the blockchain. Extract the publicly available random numbers. and validation factor Decrypt using your own private key Restore the share of the explicit Then, a two-step verification is performed: the first step is real-time verification, which involves checking the equation. To determine if the share is valid, ensure that it is a newly generated share and not a replayed old share; The second step is correctness verification, which uses bilinear mapping to check the equations. Is it valid? Once all t' valid shares have been collected, the leading company begins to reconstruct the protected core secret: the private key to the Chameleon Hash. The leading company utilizes each effective share in conjunction with polynomial coefficients generated by the leading company itself during the project initialization phase. Calculate the corresponding y-coordinate value This yields a set of pure interpolation points ( , Using this point t', the leading company reconstructs the polynomial g(x) of degree t'-1 through Lagrange interpolation; the constant term g(0) of this polynomial is the chameleon hash private key that is secretly shared and protected. ; Recover Subsequently, the leading company first used the original data block access strategy to re-execute the standard encryption process during the data encryption phase, using the original symmetric key. For the modified data Encryption is performed to obtain new ciphertext. Next, a new random mask is generated. XOR masking of the new ciphertext yields... Then use the private key that was just recovered. Find a new random number for this new ciphertext. This ensures that the chameleon hash value remains unchanged, i.e., satisfies the equation. The updated data entity is as follows: = The build is complete; the lead company uploads the new entity to the cloud server; simultaneously, it securely stores the new decryption mask locally. Update version number records; Finally, the leading company submits a signed transaction of type final confirmation to the smart contract. The transaction It contains the original modification request transaction number. A set of all confirmed transaction numbers The encrypted target component index and the new version number; after the smart contract verifies the signature, the transaction is recorded on the blockchain.

7. The method for secure collaborative editing of cross-organizational engineering data based on BOM according to claim 6, characterized in that, The specific implementation process of performing multi-version access is as follows: When a service provider needs to access the relevant drawings of a certain part, following the process described in the data sharing phase, it first obtains and decrypts the index capsule. The relevant index particles for the part are extracted from it; the index particles record the chameleon hash values ​​of each data block associated with the part. This hash value serves as a unique identifier for the data block throughout its entire lifecycle and remains unchanged after the data is initially encapsulated; service provider companies use... Use the target identifier to initiate a retrieval request to the cloud server; when making the request, optionally specify a version number. Specify the required version to view the design status of a historical version; if the request only provides... If no version number is specified, the cloud server will default to returning that it has the version number. Identifier and version number The data entity with the largest value is the latest valid version. The cloud server returns the corresponding data entity based on the request. Subsequently, the service provider company conducted version legitimacy verification; the specific verification steps were as follows: the service provider company first used a decryption token, i.e., a random mask, obtained from the leading company that corresponds to the current version number. Masked ciphertext in data entities Perform an XOR operation to recover the intermediate ciphertext. Next, extract the current random number attached to the data entity. The Chameleon Hash public key disclosed during the project initialization phase and the original chameleon hash value obtained from the index. Verify whether the following equation holds true: ; If the equation holds true, the verification passes, indicating that the data entity is either the original data entity or the person who possesses the private key. The derivative version was created by the legitimate leading company after obtaining joint approval from multiple parties and modifying the original data.

8. The method for secure collaborative editing of cross-organizational engineering data based on BOM according to claim 7, characterized in that, The specific implementation process of the behavior tracing is as follows: Any authorized participant or regulatory auditing body can conduct a complete and compliant review of any collaborative modification process by searching the blockchain; the entry point for tracing is the target component index. Or a specific transaction request ; First, the auditors used the target component index as a guide to retrieve all modification request transactions related to that component from the blockchain. Every stroke The transaction clearly records: which service provider initiated the modification request, when, and the list of public keys of the notified parties involved in the request, i.e., the list of authorized decryption public keys in the transaction; the auditor verifies... The signature confirms that the request was indeed submitted by the alleged initiator; For a The transaction, the auditor uses its Using the association condition, retrieve the set of all transactions of type "confirmed". }; each stroke The transaction records the confirmer's public key and the cryptographic verification factor provided by that party. and random numbers And the confirmed original request transaction number, through verification of each transaction. The signature confirms that these confirmation actions are genuine and not forged; Then, the auditor retrieved transactions of the final confirmation type. The transaction was based on the original of and all related of The collection serves as an index, recording the fact that the leading company has confirmed that the modifications have met the joint approval conditions and have been completed. It also includes the updated version number. This allows auditors to request the actual data entity for that version from the cloud server for cross-validation.

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