File processing method and device based on block chain and dynamic watermark, computer equipment and storage medium

Abstract

The invention relates to the technical field of block chains, can be applied to the technical field of medical treatment and finance, and discloses a file processing method and device based on a block chain and a dynamic watermark, computer equipment and a storage medium, and the method comprises the steps: receiving an original file sent by a user, carrying out the encryption processing of the original file, and storing the processed original file; when a file operation request initiated by other users on other block chains for the original file is received, calling the dynamic watermark contract to add a dynamic watermark for the original file, and using the original file added with the dynamic watermark to respond to the file operation request; meanwhile, based on the dynamic watermark and the file operation request, a file processing log is generated, the file processing log is stored in the traceability evidence chain, and the traceability evidence chain provides traceability operation of file processing by using the file processing log under the condition that a traceability demand is generated. And the actual business requirements of the fields of medical treatment, finance and the like on full-process tracking and efficient management of files are met.

Description

Technical Field

[0001] This invention relates to the field of blockchain technology and can be applied to the fields of medical and financial technologies. In particular, it relates to a document processing method, apparatus, computer equipment, and storage medium based on blockchain and dynamic watermarking. Background Technology

[0002] In the digital age, secure file handling has become a focal point of concern across numerous fields. With the rapid development of internet technology, various digital files, such as documents, images, and videos, are being processed more and more frequently across platforms and systems. Therefore, ensuring the integrity and authenticity of files during processing and preventing the loss of traceability after file leakage have become critical issues that urgently need to be addressed.

[0003] In related technologies, to protect file copyright and verify file integrity, watermarks need to be embedded in the file in a specific way. The presence of the watermark identifies the file's ownership and integrity status. Simultaneously, for file storage, files are uploaded to a blockchain for storage, leveraging the blockchain's immutability to ensure file security. Additionally, some systems record file movement information within the system for internal traceability when needed.

[0004] However, the applicant recognizes that the relevant technology has at least the following technical problems: With the continuous advancement of AI (Artificial Intelligence) technology, AI-powered watermark removal tools have emerged. These tools can effectively eliminate watermarks, making the success rate of using watermarks to protect file copyright and verify integrity relatively low. Moreover, for large files such as video files, on-chain storage leads to a significant increase in storage costs and consumes a large amount of blockchain storage resources. In addition, the circulation information can only be traced within the system. When files are transferred across platforms, it is impossible to track their circulation path, which makes it difficult to meet the needs of actual business for full-process file tracking. Summary of the Invention

[0005] This invention provides a file processing method, apparatus, computer equipment, and storage medium based on blockchain and dynamic watermarking, to solve the technical problems of low success rate, large consumption of blockchain storage resources, and difficulty in meeting the needs of full-process file tracking in actual business.

[0006] Firstly, a file processing method based on blockchain and dynamic watermarking is provided, which is applied to a private blockchain system and includes: Receive the original file sent by the user, encrypt the original file, and store the processed original file; When a file operation request is received from another user on another blockchain for the original file, the dynamic watermark contract is invoked to add a dynamic watermark to the original file, and the original file with the added dynamic watermark is used to respond to the file operation request. Simultaneously, based on the dynamic watermark and the file operation request, a file processing log is generated and stored in the traceability evidence chain. When a traceability requirement arises, the traceability evidence chain uses the file processing log to provide traceability operations for file processing.

[0007] Secondly, a file processing device based on blockchain and dynamic watermarking is provided. This device is applied to a private blockchain system and includes: An encryption module is used to receive an original file sent by a user, encrypt the original file, and store the processed original file. The watermarking module is used to call the dynamic watermarking contract to add a dynamic watermark to the original file when it receives a file operation request initiated by other users on other blockchains for the original file, and to respond to the file operation request using the original file with the added dynamic watermark. The log storage module is used to generate a file processing log based on the dynamic watermark and the file operation request, store the file processing log in the traceability evidence chain, and use the file processing log to provide traceability operations for file processing when a traceability requirement arises.

[0008] Thirdly, a computer device is provided, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the computer program, implements the steps of the file processing method based on blockchain and dynamic watermarking as described in any of the first aspects above.

[0009] Fourthly, a storage medium is provided, the computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps of the file processing method based on blockchain and dynamic watermarking as described in any of the first aspects above.

[0010] The aforementioned solution, implemented using a blockchain-based file processing method, apparatus, computer equipment, and storage medium with dynamic watermarking, can receive original files sent by users, encrypt the original files, and store the processed original files. When a file operation request for the original file is received from another user on another blockchain, a dynamic watermarking contract is invoked to add a dynamic watermark to the original file. The original file with the added dynamic watermark is then used to respond to the file operation request. Simultaneously, based on the dynamic watermark and the file operation request, a file processing log is generated and stored in the traceability evidence chain for use in traceability evidence. When traceability is required, the chain utilizes file processing logs to provide traceability operations for file processing. By adding dynamic watermarks, it prevents watermark corruption and ensures the success rate of protecting file copyright and verifying integrity through watermarks. In addition, by forming a dual-chain storage architecture with the traceability evidence chain, the private chain system stores the original files while storing the file processing logs on the traceability evidence chain. This avoids the problem of excessive storage resource consumption caused by storing a large amount of data directly on a single chain, and can record the entire file flow process in detail, meeting the actual business needs of medical, financial and other fields for full-process file tracking and efficient management. Attached Figure Description

[0011] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments of the present invention 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.

[0012] Figure 1 This is a schematic diagram of an application environment for a file processing method based on blockchain and dynamic watermarking according to an embodiment of the present invention; Figure 2 This is a flowchart illustrating a file processing method based on blockchain and dynamic watermarking in one embodiment of the present invention; Figure 3 This is a schematic diagram of the private blockchain initialization process; Figure 4 This is a flowchart illustrating a specific implementation of step S10; Figure 5 This is a flowchart illustrating a specific implementation of step S20; Figure 6 This is a flowchart illustrating a specific implementation of step S30; Figure 7 This is a schematic diagram of the overall architecture of a file processing method based on blockchain and dynamic watermarking in one embodiment of the present invention; Figure 8This is another flowchart illustrating a file processing method based on blockchain and dynamic watermarking in one embodiment of the present invention; Figure 9 This is a schematic diagram of a file processing device based on blockchain and dynamic watermarking according to an embodiment of the present invention; Figure 10 This is a schematic diagram of the structure of a computer device according to an embodiment of the present invention; Figure 11 This is another structural schematic diagram of a computer device according to one embodiment of the present invention. Detailed Implementation

[0013] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0014] The document processing method based on blockchain and dynamic watermarking provided in this invention can be applied to, for example... Figure 1 In this application environment, registered users on the private blockchain system can send original files to the system via a client. The private blockchain system receives the original files, encrypts them, and stores them. When it receives file operation requests from other users on other blockchains, the private blockchain system calls a dynamic watermark contract to add a dynamic watermark to the original file and responds to the file operation requests using the watermarked original file. Simultaneously, based on the dynamic watermark and the file operation requests, the private blockchain system generates a file processing log and stores it in the traceability evidence chain. The traceability evidence chain then uses the file processing log to provide traceability operations for file processing when traceability is required. In this invention, for documents in the medical and financial fields, dynamic watermarks are added to prevent watermark corruption, thus ensuring the success rate of using watermarks to protect document copyright and verify integrity. Furthermore, by forming a dual-chain storage architecture with the traceability evidence chain, the private chain system stores the original file while simultaneously storing the file processing log on the traceability evidence chain. This avoids the excessive storage resource consumption problem caused by storing large amounts of data directly on a single chain, and provides detailed recording of the entire file flow process, meeting the practical business needs of medical, financial, and other fields for full-process file tracking and efficient management. The client can be, but is not limited to, various personal computers, laptops, smartphones, tablets, and portable wearable devices. The invention will be described in detail below through specific embodiments.

[0015] Please see Figure 2 As shown, Figure 2 A flowchart illustrating a file processing method based on blockchain and dynamic watermarking provided in this embodiment of the invention, applied to a private blockchain system, includes the following steps: S10: Receive the original file sent by the user, encrypt the original file, and store the processed original file.

[0016] The document processing method based on blockchain and dynamic watermarking provided by this invention can be applied to private blockchain systems. These systems can be online medical or financial platforms that store data on their platforms. The private blockchain is a blockchain network built and operated within this system, where the number of nodes and access permissions are controlled, allowing only authorized entities to participate in network maintenance and data interaction. This closed nature endows the private blockchain with a high degree of privacy and controllability. The private blockchain employs distributed ledger technology, with ledger data synchronously stored and updated across multiple authorized nodes. Each node maintains a complete or partial copy of the ledger, ensuring data redundancy and high availability. Even if some nodes fail or are attacked, the entire network can still operate normally, guaranteeing data integrity and consistency. Before implementing any embodiment of this invention, the private blockchain needs to be initialized; see [link to relevant documentation]. Figure 3 During initialization, the administrator node in the private blockchain initiates a request to the CA (Certificate Authority System). The CA system generates a root certificate (specifically, using the SM2 algorithm). The root certificate is the foundation of the entire private blockchain certificate system, used to verify the legitimacy of other certificates, ensuring the trustworthiness and security of the certificate issuance process, and providing basic guarantees for identity authentication and data encryption in the private blockchain. Subsequently, the CA system is responsible for deploying at least three consensus nodes to the node cluster. The node cluster completes node certificate registration and feeds back relevant information to the CA system. Afterward, the CA system returns the network configuration to the administrator node, while the administrator node prompts the node cluster to initialize the smart contract and returns the generated contract address to the administrator node. This completes a series of key configuration and information interaction steps for the initialization of the private blockchain, laying the foundation for subsequent file storage and the addition of dynamic watermarks.

[0017] In a private blockchain system environment, relay nodes are set up to connect with users. When a user sends an original file via a relay node, the private blockchain system first encrypts the received file. After encryption, the encrypted file is stored in designated storage nodes within the private blockchain system. These storage nodes can be distributed across different locations within the private blockchain network to improve data reliability and availability. Thus, by encrypting and storing the original file within the private blockchain system, file privacy is effectively protected, preventing unauthorized access and tampering. This provides reliable file storage for scenarios with high data security requirements, such as those in the medical and financial sectors.

[0018] For example, in a large hospital, patient medical records contain a wealth of sensitive information, such as personal identification, disease diagnosis, and treatment plans. Doctors can send the original patient medical records to a private blockchain system, which encrypts and stores the records. This ensures that only authorized medical personnel can access and decrypt these records, protecting patient privacy. Similarly, when financial institutions process customer financial reports and transaction records, which involve customer funds and trade secrets, they can encrypt and store the original documents in a private blockchain system. Only authorized internal personnel can access the document content, effectively preventing information leakage and unauthorized alteration, and maintaining the stability of the financial market and customer trust.

[0019] Among them, such as Figure 4 As shown, step S10, which involves receiving the original file sent by the user, encrypting the original file, and storing the processed original file, includes the following steps: S11: Based on the relay node, receive the original file sent by the user and identify whether the file attribute information of the original file meets the fragmentation conditions.

[0020] In the file receiving phase of the private blockchain system, relay nodes receive the original files sent by users. These relay nodes act as intermediate nodes in file transmission, buffering and forwarding to ensure stable and efficient file transfer to the private blockchain system. After receiving the original file, the private blockchain system identifies its file attribute information, which includes at least file type and file size. File type refers to the file format, such as DICOM (Digital Imaging and Communications in Medicine) format medical image files in the medical field, or PDF format financial statement files in the financial field; file size indicates the file's dimensions. The private blockchain system compares the file type with the preset type indicated by the fragmentation conditions, and simultaneously compares the file size with the size threshold indicated by the fragmentation conditions. Specifically, if the file type matches the preset type and the file size is greater than or equal to the size threshold, the file attribute information is deemed to meet the fragmentation conditions; if the file type does not match the preset type or the file size is less than the size threshold, the file attribute information is determined to not meet the fragmentation conditions.

[0021] In this way, by accurately identifying file attribute information and making judgments based on fragmentation conditions, the subsequent processing method can be determined according to the actual characteristics of the file, providing a basis for rationally allocating storage resources and optimizing the file processing flow, thereby improving the efficiency and targeting of file processing.

[0022] For example, in a hospital's radiology department, doctors need to upload a large number of DICOM format medical image files to a private blockchain system for storage and management. These image files are typically large, such as high-resolution CT (Computed Tomography) images. When a file is received via a relay node, the system identifies the file type as DICOM, matching the preset medical image file type, and if the file size exceeds a set size threshold (e.g., 10MB), then the file attributes meet the fragmentation criteria, preparing for subsequent fragmentation processing. Similarly, a financial institution needs to store a large number of PDF format financial statement files. Some of these files are rich in content and large in size. When the files are transmitted to the private blockchain system via a relay node, the system identifies the file type as PDF. If this matches the preset financial statement file type and the file size reaches or exceeds a size threshold (e.g., 10MB), then the system meets the fragmentation criteria for appropriate subsequent processing.

[0023] S12: When the file attribute information meets the fragmentation conditions, the original file is fragmented and encrypted, and the fragmented and encrypted original file is stored.

[0024] In this embodiment of the invention, after determining that the file attribute information meets the fragmentation conditions, the private blockchain system performs fragmentation on the original file according to a preset file fragmentation standard. The file fragmentation standard is a rule pre-set based on the characteristics and storage requirements of the file, such as fragmenting according to a fixed size. After fragmentation, the original file is divided into multiple file fragments. Subsequently, the private blockchain system encrypts each file fragment. The encryption algorithm can be selected according to the security requirements of the file, such as AES (Advanced Encryption Standard) algorithm, SM4 (SM4 Cryptographic Algorithm), etc. After encryption, the private blockchain system generates a corresponding fragment content identifier for each file fragment. The fragment content identifier is information used to uniquely identify each encrypted file fragment, specifically it can be a CID (Content Identifier). After obtaining multiple fragment content identifiers, the private blockchain system uses these identifiers to construct an identifier index tree. The identifier index tree is a data structure that can efficiently organize and manage fragment content identifiers, facilitating subsequent searching and access to file fragments. Finally, the private blockchain system stores the identifier index tree, thus completing the fragmentation and encryption of the original file.

[0025] In this way, by fragmenting and encrypting files that meet the fragmentation criteria, and storing the fragment content identifiers as an index tree, we can improve file storage efficiency by dividing large files into smaller fragments for distributed storage and management. On the other hand, encryption ensures the security of file fragments, while the identifier index tree improves the retrieval efficiency of file fragments, meeting the needs of the medical and financial sectors for secure file storage and fast access.

[0026] For example, for large DICOM medical image files from the aforementioned hospitals, they can be segmented into multiple smaller fragments according to preset standards. Each fragment is encrypted, and a fragment content identifier is generated and stored in an index tree. This way, when doctors need to view the images later, they can quickly locate the required file fragment through the index tree, decrypt it, and stitch it together for display, ensuring both secure storage of the image files and improved viewing efficiency. As another example, large PDF financial statement files from financial institutions, after being segmented and encrypted, are stored in an identifier index tree. When the report needs to be viewed, the relevant fragment can be quickly found based on the index tree, decrypted, and the complete report content presented, ensuring the security of the report data and ease of access, meeting the requirements of data security and efficient processing in financial operations.

[0027] S13: When the file attribute information does not meet the fragmentation conditions, the original file is encrypted as a whole to obtain the overall content identifier of the original file, and the overall content identifier is stored to complete the storage of the original file.

[0028] In this embodiment of the invention, if the file attribute information does not meet the fragmentation conditions, the private blockchain system will directly encrypt the original file as a whole. Specifically, algorithms such as AES and SM4 can be used to encrypt the original file to ensure the security of the file content. After encryption, an overall content identifier is generated for the original file. This overall content identifier is used to uniquely identify the entire encrypted file and can also be a whole CID. Finally, the overall content identifier is stored, thus completing the storage operation of the original file. In this way, by encrypting and storing files that do not meet the fragmentation conditions as a whole, the processing flow is simplified, unnecessary fragmentation operations are avoided, and the efficiency of file processing is improved. At the same time, overall encryption can also ensure the security of the file, meeting the basic requirements for secure file storage in the medical and financial fields.

[0029] For example, some small, commonly formatted text medical record files in hospitals, such as patient basic information documents, may not meet the sharding criteria if the file type is inconsistent with the preset type or the file size is smaller than the size threshold. The private blockchain system directly encrypts the entire file, generating a complete content identifier and storing it. This ensures the security of the medical record files while simplifying the processing flow and improving storage efficiency. Similarly, small notification documents or simple transaction confirmation documents from financial institutions, if they do not meet the sharding criteria, can be encrypted as a whole, generating a complete content identifier for storage. This ensures file security while quickly completing the file storage operation, meeting the high efficiency requirements of file processing in financial operations.

[0030] S20: When a file operation request for the original file is received from another user on another blockchain, the dynamic watermark contract is invoked to add a dynamic watermark to the original file, and the original file with the added dynamic watermark is used to respond to the file operation request.

[0031] In this embodiment of the invention, when the private blockchain system receives a file operation request from another user on another blockchain (which may be a consortium blockchain or a public blockchain) for a stored original file, the private blockchain system invokes a dynamic watermark contract pre-deployed on the private blockchain system. The dynamic watermark contract is a smart contract that defines the rules and algorithms for adding a dynamic watermark to a file. Unlike traditional static watermarks, dynamic watermarks can dynamically generate a bimodal watermark based on information such as the file's operation address, operation time, and the user performing the operation, providing stronger anti-tampering and tracking capabilities. After the contract is executed, a dynamic watermark can be added to the original file. Then, the original file with the added dynamic watermark can be used to respond to file operation requests, such as allowing users to view, download, or edit the file, thereby effectively preventing the watermark from being destroyed and ensuring the success rate of protecting file copyright and verifying integrity through watermarks.

[0032] For example, a large hospital stores patients' medical records in a private blockchain system. When other partner insurance institutions request to view these records, the private blockchain system uses a dynamic watermarking contract to add a dynamic watermark to the file, including the viewing location, viewing time, and viewing institution information, ensuring that patient privacy is not compromised. As another example, a financial institution stores clients' financial reports and transaction records in a private blockchain system. When other partner insurance institutions request to view these documents, a dynamic watermark is added to the report, containing information such as the viewing location, institution name, and viewing time.

[0033] Among them, such as Figure 5 As shown, in step S20, that is, when a file operation request for the original file is received from another user on another blockchain, the dynamic watermark contract is invoked to add a dynamic watermark to the original file, and the original file with the added dynamic watermark is used to respond to the file operation request, including the following steps: S21: Receive file operation requests and identify the file operation requests.

[0034] In this embodiment of the invention, the private blockchain system maintains a constant monitoring state. When a file operation request is initiated by another user on another blockchain regarding the original file, the private blockchain system receives the request. Subsequently, the file operation request is identified, and the user's specific operational intent is determined by parsing the instruction information within the request. The other blockchains can be consortium blockchains or public blockchains that have cross-chain interaction requirements with the private blockchain system. The file operation request contains key information such as the type of operation the user wants to perform on the original file. By identifying this key information, different operation requests, such as downloading or forwarding, can be accurately distinguished, ensuring that corresponding operations are performed based on the user's actual needs. This improves the accuracy and relevance of the response, providing support for ensuring the smooth execution of the file operation process.

[0035] For example, in a medical information sharing scenario, a hospital's private blockchain system stores patients' original medical image files. When another collaborating hospital's blockchain sends a file operation request to the private blockchain system, the private blockchain system, upon receiving the request, identifies that the collaborating hospital wants to download the images for further diagnosis, providing clear direction for subsequent permission verification and file processing. As another example, a financial institution's private blockchain system manages important original financial report files. When a regulatory agency's blockchain sends a file operation request, the private blockchain system identifies that the regulatory agency wants to download the report for review, thus initiating the corresponding processing flow to ensure the smooth conduct of regulatory work.

[0036] S22: When identifying and determining that a file operation request instructs the download of the original file, verify the permissions of other users. If the verification is successful, call the dynamic watermark contract to add explicit and implicit watermarks as dynamic watermarks to the original file so that other users can download it.

[0037] In this embodiment of the invention, when a file operation request is identified indicating that the original file should be downloaded, the private chain system first verifies the permissions of other users. The permission verification can be based on pre-set permission management rules to check whether other users are qualified to download the original file.

[0038] Upon successful verification, the private blockchain system invokes the dynamic watermarking contract. This contract, a smart contract, defines the specific rules and algorithms for adding dynamic watermarks to files. By invoking the contract, the private blockchain system adds both explicit and implicit watermarks to the original file. Specifically, to construct the watermark, the system obtains user identifiers (such as a user's unique digital identity DID) and geocoding (such as GeoHash) from other users, determines the file hash value of the original file (such as a TxID used to uniquely identify the file content), and constructs a first timestamp based on the time the file operation request was received. Using this information, the system then begins the watermark construction process. The explicit watermark is the watermark information visible to the user. The private blockchain system combines the user identifier and the first timestamp to form the first explicit text, then invokes the dynamic watermarking contract to add the explicit watermark to the original file using this text, making the watermark visible to the user. Meanwhile, the private blockchain system will use invisible watermark embedding technology (such as DCT-PM frequency domain embedding technology, which has the characteristics of being resistant to editing and screen capture) to process the file hash value and user geocoding, and add an invisible watermark to the original file. Thus, through explicit and implicit bimodal watermarking, dynamic watermarking can be added.

[0039] Afterwards, the private blockchain system will query the file formats associated with other blockchains and convert the original file with the added dynamic watermark according to the file format to meet the download needs of other users.

[0040] Through the above process, dynamic watermarks are added during the download operation. The explicit watermark in the dynamic watermark allows the recipient to clearly identify the source and usage information of the file, while the implicit watermark provides a deeper level of copyright protection and integrity verification without affecting the user's normal viewing. Moreover, the dynamic watermark can be continuously refreshed over time. At the same time, the file format is converted according to the recipient's blockchain to improve the file's compatibility and usability, ensuring the normal use of the file in different blockchain environments.

[0041] Continuing with the example of medical information sharing, after a partner hospital verifies the information, it downloads the patient's medical image files. A visible watermark displays the partner hospital's DID (Decentralized Identifier) ​​and download timestamp, while a hidden watermark embeds the file's hash value and the hospital's geocode. If the image files are subsequently illegally disseminated, the visible watermark allows tracing back to the downloading hospital, while the hidden watermark verifies the file's integrity and originality. Furthermore, the private blockchain system converts the image files into a format supported by the partner hospital's blockchain, facilitating viewing and diagnosis by their doctors. Similarly, in the financial sector, after a regulatory agency verifies the information and downloads a financial report, a visible watermark includes the agency's identifier and download time, while a hidden watermark ensures the report's content is not tampered with. After format conversion, the agency can easily access and use the report for review, while the watermark information protects the report's copyright and security.

[0042] S23: When identifying and determining the file operation request instruction to forward the original file, determine the recipient of the forwarding operation, refer to the recipient's recipient information, call the dynamic watermark contract to update the dynamic watermark currently added to the original file, forward the updated original file to the recipient, and record the file flow path of this forwarding.

[0043] In this embodiment of the invention, when a file operation request is identified and determined to indicate the forwarding of the original file, the private blockchain system first identifies the recipient of the forwarding operation and obtains the recipient's information, which includes key content such as the recipient's identifier and geocode. Referring to the recipient information, the private blockchain system invokes a dynamic watermarking contract to update the dynamic watermark currently added to the original file. Specifically, the private blockchain system determines the recipient's identifier and geocode based on the recipient information, determines the file hash value of the original file, constructs a second timestamp based on the time the file operation request was received, and combines the recipient's identifier and the second timestamp to form a second explicit text. The dynamic watermarking contract uses this second explicit text to update the explicit watermark in the dynamic watermark currently added to the original file. Simultaneously, an implicit watermark embedding technique is used to process the file hash value and the recipient's geocode to update the implicit watermark in the dynamic watermark currently added to the original file. After the watermark update is completed, the updated original file is forwarded to the recipient, and the file flow path of this forwarding is recorded for subsequent tracking and querying.

[0044] It's important to note that since forwarding files typically occurs after other users have viewed the file, the original file may already have a dynamic watermark embedded. In this case, if another user requests to forward the original file, the private blockchain system will update the dynamic watermark to dynamically change it, further enhancing file security. Additionally, in practical applications, if the original file didn't previously have a dynamic watermark—meaning other users haven't viewed the original file but only forwarded it—a dynamic watermark can be added directly without requiring an update.

[0045] In this way, updating the dynamic watermark during the forwarding process can reflect the file's circulation information in real time, making the file's copyright and usage trajectory clearer. In addition, recording the file circulation path provides detailed data support for file traceability. In the event of copyright disputes or file security issues, the file circulation process can be quickly and accurately tracked, protecting the rights of the file owner.

[0046] For example, when Hospital A forwards a patient's medical imaging files to Hospital B, the private blockchain system updates the explicit watermark to Hospital B's identifier and forwarding timestamp, and updates the implicit watermark by embedding relevant geocoding and other information. It records the path the file takes from Hospital A's private blockchain system to Hospital B. If subsequent abnormal use of the imaging files occurs, the source can be traced through the transfer path and watermark information, ensuring the security and proper use of patient imaging data. As another example, when a financial institution forwards a financial report to a partner institution, it updates the watermark information to reflect the new recipient and usage time, and records the file transfer path. If the report content is leaked or tampered with during the cooperation process, the problem can be quickly located based on the transfer path and watermark, maintaining the security and stability of financial information.

[0047] S30: Simultaneously, based on dynamic watermarks and file operation requests, generate file processing logs and store them in the traceability evidence chain. When a traceability requirement arises, the traceability evidence chain uses the file processing logs to provide traceability operations for file processing.

[0048] While adding dynamic watermarks to the original files and responding to file operation requests, the private blockchain system also generates file processing logs based on the dynamic watermark information and the content of the file operation requests. The file processing logs record in detail the file operation time, the user performing the operation, the operation type (such as viewing, downloading, editing, etc.), and information related to the dynamic watermark. The private blockchain system then stores these file processing logs in the traceability evidence chain, a blockchain used to store file operation records. This chain works in conjunction with the private blockchain system storing the original files, forming a dual-chain storage architecture. When a traceability requirement arises, the traceability evidence chain utilizes the stored file processing logs to provide traceability operations for file processing, such as querying the file's operation history and tracing the file's flow path. In this way, using a dual-chain storage architecture to simultaneously store files and record the process of file operations avoids storing large amounts of data directly on a single chain, reducing the consumption of blockchain storage resources. Simultaneously, it enables detailed recording of the entire file flow process, meeting the needs of real-world business operations in the medical and financial sectors for full-process file tracking, and improving the transparency and traceability of file management.

[0049] For example, a large hospital stores patient medical records in a private blockchain system. When other cooperating insurance institutions request to view these records, the private blockchain system generates a file processing log and stores it in a traceability evidence chain. In the event of a medical record leak, the traceability evidence chain can be used to quickly trace the flow of the medical records, identify the point at which the problem occurred, and take timely measures to protect patient privacy. As another example, in financial transactions, a transaction contract goes through multiple departments and personnel from drafting and review to execution. By storing the transaction contract in a private blockchain system and storing the operation records in a traceability evidence chain, in the event of a transaction dispute, the traceability evidence chain can be used to view the contract's operation history, clarify the responsibilities of each link, provide strong evidence for resolving disputes, and maintain the normal order of the financial market.

[0050] Among them, such as Figure 6 As shown, step S30, which involves generating a file processing log based on the dynamic watermark and file operation request, and storing the file processing log in the traceability evidence chain, includes the following steps: S31: Obtain the identifier of the private blockchain system as the source blockchain identifier, and obtain the identifiers of other blockchains as the target blockchain identifier.

[0051] In this embodiment of the invention, during the process of generating file processing logs based on dynamic watermarks and file operation requests, the source and destination information of the file operation must first be clarified. Therefore, the private blockchain system obtains its own identifier through an internally preset blockchain identifier management mechanism, using it as the source blockchain identifier. The source blockchain identifier is used to uniquely identify the private blockchain system that initiated the file operation-related processing. Simultaneously, the private blockchain system obtains the identifiers of other blockchains, using them as target blockchain identifiers. The target blockchain identifier identifies the external blockchain that initiated the file operation request. It should be noted that the blockchain identifier mentioned in this embodiment of the invention is a unique code or name pre-set during the construction of the blockchain network, capable of accurately distinguishing different blockchains.

[0052] By accurately acquiring the source and target blockchain identifiers, the origin and destination information of file operations can be clearly recorded, providing foundational data for subsequent file tracing. This allows the tracing process to clearly identify the flow direction of files between different blockchains, enhancing the completeness and accuracy of tracing information. For example, in a cross-chain sharing scenario for medical information, a hospital's private blockchain system stores patients' medical image files. When another partner hospital's blockchain initiates a file download request, it acquires the identifier of the hospital's private blockchain system as the source blockchain identifier and the identifier of the partner hospital's blockchain as the target blockchain identifier. During subsequent tracing, it can be clearly determined which hospital's private blockchain system the image file originated from and which partner hospital's blockchain it flowed to. As another example, a financial institution's private blockchain system manages financial reporting documents. When a regulatory agency's blockchain initiates a document viewing request, it acquires the source blockchain identifier of the financial institution's private blockchain system and the target blockchain identifier of the regulatory agency's blockchain. During subsequent tracing of operations on the reporting documents, it can be clearly determined that the report was provided to the regulatory agency's blockchain from the financial institution's private blockchain system, facilitating the tracking of file flow.

[0053] S32: Based on the signatures of other users on the original file during authentication, generate an aggregate signature, organize the dynamic watermark, source chain identifier, target chain identifier and aggregate signature, generate a file processing log, and transmit the file processing log to the traceability evidence chain so that the traceability evidence chain stores the file processing log in the traceability chain database.

[0054] In practical applications, other users need to authenticate themselves before performing file operations. During the authentication process, the original file is signed. Therefore, the private blockchain system collects this signature information and uses aggregate signature technology to generate aggregate signatures. Aggregate signatures integrate multiple signature information into one signature, which can reduce the amount of data storage while ensuring the validity and security of the signature. Specifically, it can be BLS (Boneh-Lynn-Shacham, a cryptographic digital signature scheme based on bilinear mapping) aggregate signature.

[0055] Then, the dynamic watermark information, the previously obtained source chain identifier, target chain identifier, and generated aggregate signature are organized and used to generate a file processing log according to a preset log format. After generating the log, the file processing log is transmitted to the tracing evidence chain. Upon receiving the log, the tracing evidence chain stores it in the tracing chain database. The tracing chain database is used to store the file processing log and has high reliability and security to ensure the integrity and queryability of the log data.

[0056] By generating aggregated signatures and integrating relevant information to create file processing logs, data storage volume can be effectively reduced while ensuring the integrity and security of user authentication information. Furthermore, storing these logs in the traceability chain database provides a reliable data storage and query mechanism for file traceability. When traceability is needed, relevant information about file operations can be quickly and accurately obtained, meeting the needs of the medical and financial sectors for end-to-end file tracking and security management. For example, when users at partner hospitals download medical image files, they authenticate and sign. The private blockchain system uses the accumulated signatures to generate aggregated signatures, combining the dynamic watermark of the image file, the source chain identifier of the hospital's private blockchain system, the target chain identifier of the partner hospital's blockchain, and the aggregated signature to generate a file processing log, which is then stored in the traceability chain. When copyright disputes or leaks of image files occur, querying the logs through the traceability chain allows for understanding the file operation process, source, and target, clarifying responsibility, and protecting patient privacy and hospital rights. For example, when regulatory agencies review financial reports, they sign them. The private blockchain system uses the accumulated signatures to generate an aggregated signature and generate a file processing log, which is then stored in the traceability evidence chain. If the report content is abnormally disseminated or tampered with, the log information in the traceability evidence chain can be used to trace the report's operational process, determine which link in the process went wrong, and ensure the safe and compliant use of financial information.

[0057] In another alternative implementation, the private blockchain system continuously monitors for traceability needs. When a traceability need is detected, the traceability evidence chain invokes a pre-deployed audit contract. This audit contract, a smart contract, defines the specific rules and operational steps of the traceability process. After invoking the audit contract, the traceability process officially begins. The traceability evidence chain extracts relevant file processing logs from the traceability blockchain database and integrates this log information according to preset rules and formats to generate an evidence package. The evidence package encapsulates information related to the file processing process, including detailed records of file operations, watermark information, blockchain identifiers, and other key content. After generating the evidence package, the traceability evidence chain transmits it to a designated regulatory agency. Upon receiving the evidence package, the regulatory agency can refer to its contents to perform traceability processing to ascertain the file's circulation process, operational details, and other information.

[0058] By invoking an audit contract to initiate a standardized tracing process and generating an evidence package for transmission to regulatory agencies, the tracing work can be carried out efficiently and systematically. Furthermore, the evidence package integrates comprehensive document processing information, providing regulatory agencies with clear and accurate tracing evidence, improving the efficiency and accuracy of tracing, facilitating timely identification and resolution of problems, and ensuring the safe and compliant use of documents. For example, in medical information management, suppose a patient's medical image file experiences abnormal dissemination, generating a tracing requirement. After detecting this requirement, the tracing evidence chain invokes an audit contract to initiate the tracing process. The audit contract, according to preset rules, extracts the file processing logs from the tracing chain database, showing the image file's journey from original storage to multiple forwardings and other operations. This log information is then integrated to generate an evidence package, which includes the time of each operation, the blockchain identifier of the operator, and added watermark information. The evidence package is then transmitted to the medical regulatory agency. By referring to the evidence package, the agency can clearly understand how the image file flowed from the hospital's private blockchain system, which partner hospitals or institutions' blockchains it passed through, and whether any violations occurred, thus enabling timely measures to protect patient privacy and the security of medical information. For example, in the financial sector, if a financial institution's important financial report is suspected of being leaked, a need for tracing the source arises. After detecting this need, the tracing evidence chain invokes the audit contract to initiate the tracing process. The audit contract guides the system to extract relevant file processing logs from the tracing chain database, generating an evidence package containing the report operation time, the blockchain of the operating party, signature information, watermark content, etc., and transmitting it to the financial regulatory agency. Based on the evidence package, the regulatory agency can accurately trace the flow path of the report, determine which link the leak occurred at, and safeguard the normal order of the financial market and the legitimate rights and interests of financial institutions.

[0059] In summary, the overall architecture of the technical solution of this invention can be found in [reference needed]. Figure 7 When a file uploaded by a user via the client is received for storage, the system first verifies the user's permissions using the permission management module to ensure the user has legitimate authorization. On one hand, after permission verification, a smart contract is invoked to automate business logic execution and provide lightweight evidence storage. A public traceability chain records file operation logs and other information, and cross-chain relay enables BLS aggregation and interaction with external systems, ensuring data traceability. On the other hand, a dynamic watermarking engine generates dynamic dual-mode watermarks, including explicit and implicit watermarks, providing dual protection for the file. Simultaneously, the private chain system manages private data, combining IPFS storage for sharding and encryption, improving data storage security and efficiency.

[0060] See Figure 8The logical process of this invention's technical solution can be summarized as follows: Assume that the original file sent by user A on chain A is received by a relay node. After receiving the file, the relay node converts its format and provides it to user B on chain B. Simultaneously, it generates a cross-chain certificate and, by calling an audit contract, stores information including the source chain identifier, target chain identifier, and BLS aggregate signature in the traceability chain database. When a file leakage event occurs, the traceability process is initiated. The traceability system can query cross-chain records. When needed, the traceability chain database returns an evidence package containing the original TxID, conversion log, and signature verification. If there is a need for judicial evidence, the evidence collection terminal obtains the evidence package and generates judicial evidence, which is then submitted to the regulatory agency, thereby achieving full traceability and supervision of the cross-chain file transfer process.

[0061] As can be seen, in the above solution, for documents in the medical and financial fields, dynamic watermarks are added to prevent the watermarks from being destroyed, thus ensuring the success rate of protecting document copyright and verifying integrity through watermarks. In addition, by forming a dual-chain storage architecture with the traceability evidence chain, the private chain system stores the original documents while storing the document processing logs on the traceability evidence chain. This avoids the problem of excessive storage resource consumption caused by storing a large amount of data directly on a single chain, and can record the entire document flow process in detail, meeting the actual business needs of medical, financial and other fields for full-process document tracking and efficient management.

[0062] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0063] In one embodiment, a file processing device based on blockchain and dynamic watermarking is provided, which corresponds one-to-one with the file processing method based on blockchain and dynamic watermarking described in the above embodiments. For example... Figure 9 As shown, the file processing device based on blockchain and dynamic watermarking includes an encryption module 901, a watermark adding module 902, and a log storage module 903. Detailed descriptions of each functional module are as follows: The encryption module 901 is used to receive the original file sent by the user, encrypt the original file, and store the processed original file. The watermarking module 902 is used to call the dynamic watermarking contract to add a dynamic watermark to the original file when it receives a file operation request initiated by other users on other blockchains for the original file, and to respond to the file operation request using the original file with the added dynamic watermark. The log storage module 903 is used to generate a file processing log based on the dynamic watermark and the file operation request, store the file processing log in the traceability evidence chain, and use the file processing log to provide traceability operations for file processing when a traceability requirement is generated.

[0064] In one embodiment, the encryption module 901 is configured to receive the original file sent by the user based on a relay node, identify whether the file attribute information of the original file meets the fragmentation conditions, wherein the file attribute information includes at least file type and file size. When the file type is consistent with a preset type indicated by the fragmentation conditions and the file size is greater than or equal to a size threshold indicated by the fragmentation conditions, the file attribute information is determined to meet the fragmentation conditions; when the file type is inconsistent with the preset type or the file size is less than the size threshold, the file attribute information is determined to not meet the fragmentation conditions. When the file attribute information meets the fragmentation conditions, the original file is fragmented and encrypted, and the fragmented and encrypted original file is stored. When the file attribute information does not meet the fragmentation conditions, the original file is encrypted as a whole to obtain an overall content identifier of the original file, and the overall content identifier is stored to complete the storage of the original file.

[0065] In one embodiment, the encryption module 901 is used to divide the original file into multiple file segments according to a preset file segmentation standard; to encrypt each file segment to generate a segment content identifier corresponding to each file segment, thereby obtaining multiple segment content identifiers; to construct an identifier index tree using the multiple segment content identifiers, and to store the identifier index tree to complete the segmentation and encryption processing of the original file.

[0066] In one embodiment, the watermark adding module 902 is used to receive the file operation request and identify the file operation request; when the identification determines that the file operation request indicates downloading the original file, the permissions of the other users are verified; if the verification is successful, the dynamic watermark contract is invoked to add explicit and implicit watermarks as dynamic watermarks to the original file so that the other users can download it; when the identification determines that the file operation request indicates forwarding the original file, the recipient of the forwarding operation is determined, and with reference to the recipient's recipient information, the dynamic watermark contract is invoked to update the currently added dynamic watermark of the original file, the updated original file is forwarded to the recipient, and the file flow path of this forwarding is recorded.

[0067] In one embodiment, the watermarking module 902 is used to obtain the user identifier and user geocode of the other users, determine the file hash value of the original file, and construct a first timestamp with reference to the time point when the file operation request is received; combine the user identifier and the first timestamp to form a first explicit text, and call the dynamic watermarking contract so that the dynamic watermarking contract uses the first explicit text to add an explicit watermark to the original file; simultaneously call the dynamic watermarking contract to process the file hash value and the user geocode using invisible watermark embedding technology to add an invisible watermark to the original file, so that the explicit watermark and the invisible watermark are used as the dynamic watermark added to the original file; query the file format associated with the other blockchain, and convert the original file after adding the dynamic watermark with reference to the file format so that the other users can download it.

[0068] In one embodiment, the watermark adding module 902 is used to determine the recipient identifier and recipient geocode based on the recipient information, determine the file hash value of the original file, and construct a second timestamp with reference to the time point when the file operation request was received; combine the recipient identifier and the second timestamp to form a second explicit text, and call the dynamic watermark contract so that the dynamic watermark contract updates the explicit watermark in the currently added dynamic watermark of the original file using the second explicit text; simultaneously, call the dynamic watermark contract to process the file hash value and the recipient geocode using invisible watermark embedding technology, and update the invisible watermark in the currently added dynamic watermark of the original file, so as to complete the update of the currently added dynamic watermark of the original file.

[0069] In one embodiment, the log storage module 903 is used to obtain the identifier of the private chain as the source chain identifier and the identifier of the other blockchain as the target chain identifier; based on the signature of the original file by the other user during identity verification, an aggregate signature is generated; the dynamic watermark, the source chain identifier, the target chain identifier, and the aggregate signature are organized to generate the file processing log, and the file processing log is transmitted to the traceability evidence chain, so that the traceability evidence chain stores the file processing log in the traceability chain database; wherein, when the traceability requirement is detected, the traceability evidence chain calls the audit contract to start the traceability process, and generates an evidence package based on the file processing log, and transmits the evidence package to the regulatory agency so that the regulatory agency can refer to the evidence package for traceability processing.

[0070] This invention provides a file processing device based on blockchain and dynamic watermarking. It receives original files sent by users, encrypts them, and stores the processed files. When a file operation request is received from another user on another blockchain, a dynamic watermarking contract is invoked to add a dynamic watermark to the original file. The device then responds to the file operation request using the watermarked original file. Simultaneously, based on the dynamic watermark and the file operation request, a file processing log is generated and stored in a traceability evidence chain. This traceability evidence chain provides traceability operations for file processing when traceability is required. By adding a dynamic watermark, the watermark is protected from damage, ensuring the success rate of protecting file copyright and verifying integrity through watermarking. Furthermore, by forming a dual-chain storage architecture with the traceability evidence chain, the private blockchain system stores the original files while simultaneously storing the file processing logs on the traceability evidence chain. This avoids the excessive storage resource consumption caused by storing large amounts of data directly on a single chain, and provides detailed recording of the entire file flow process, meeting the practical business needs of medical, financial, and other fields for full-process file tracking and efficient management.

[0071] Specific limitations regarding the file processing device based on blockchain and dynamic watermarking can be found in the limitations of the file processing method based on blockchain and dynamic watermarking mentioned above, and will not be repeated here. Each module in the aforementioned file processing device based on blockchain and dynamic watermarking can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in or independent of the processor in a computer device in hardware form, or stored in the memory of a computer device in software form, so that the processor can call and execute the operations corresponding to each module.

[0072] In one embodiment, a computer device is provided, which may be a server, and its internal structure diagram may be as follows: Figure 10 As shown, the computer device includes a processor, memory, network interface, and database connected via a system bus. The processor provides computing and control capabilities. The memory includes non-volatile and / or volatile storage media and internal memory. The non-volatile storage media stores the operating system, computer programs, and database. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage media. The network interface is used to communicate with external clients via a network connection. When the computer program is executed by the processor, it implements the functions or steps of a blockchain-based dynamic watermarking file processing method on the server side.

[0073] In one embodiment, a computer device is provided, which may be a client, and its internal structure diagram may be as follows: Figure 11As shown, the computer device includes a processor, memory, network interface, display screen, and input devices connected via a system bus. The processor provides computing and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs stored in the non-volatile storage media. The network interface is used to communicate with an external server via a network connection. When executed by the processor, the computer program implements client-side functions or steps of a file processing method based on blockchain and dynamic watermarking.

[0074] In one embodiment, a computer device is provided, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to perform the following steps: Receive the original file sent by the user, encrypt the original file, and store the processed original file; When a file operation request is received from another user on another blockchain for the original file, the dynamic watermark contract is invoked to add a dynamic watermark to the original file, and the original file with the added dynamic watermark is used to respond to the file operation request. Simultaneously, based on the dynamic watermark and the file operation request, a file processing log is generated and stored in the traceability evidence chain. When a traceability requirement arises, the traceability evidence chain uses the file processing log to provide traceability operations for file processing.

[0075] In one embodiment, a computer-readable storage medium is provided having a computer program stored thereon, the computer program performing the following steps when executed by a processor: Receive the original file sent by the user, encrypt the original file, and store the processed original file; When a file operation request is received from another user on another blockchain for the original file, the dynamic watermark contract is invoked to add a dynamic watermark to the original file, and the original file with the added dynamic watermark is used to respond to the file operation request. Simultaneously, based on the dynamic watermark and the file operation request, a file processing log is generated and stored in the traceability evidence chain. When a traceability requirement arises, the traceability evidence chain uses the file processing log to provide traceability operations for file processing.

[0076] It should be noted that the functions or steps that can be implemented by the computer-readable storage medium or computer device described above can be referred to the relevant descriptions on the server side and client side in the foregoing method embodiments. To avoid repetition, they will not be described one by one here.

[0077] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the embodiments of the above methods. Any references to memory, storage, databases, or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in a variety of forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), dual data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), RAMbus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.

[0078] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is used as an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above.

[0079] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A file processing method based on blockchain and dynamic watermarking, characterized in that, The method is applied to a private blockchain system, including: Receive the original file sent by the user, encrypt the original file, and store the processed original file; When a file operation request is received from another user on another blockchain for the original file, the dynamic watermark contract is invoked to add a dynamic watermark to the original file, and the original file with the added dynamic watermark is used to respond to the file operation request. Simultaneously, based on the dynamic watermark and the file operation request, a file processing log is generated and stored in the traceability evidence chain. When a traceability requirement arises, the traceability evidence chain uses the file processing log to provide traceability operations for file processing.

2. The method according to claim 1, characterized in that, The process of receiving the original file sent by the user, encrypting the original file, and storing the processed original file includes: Based on the relay node receiving the original file sent by the user, the system identifies whether the file attribute information of the original file meets the fragmentation conditions. The file attribute information includes at least file type and file size. When the file type is consistent with the preset type indicated by the fragmentation conditions and the file size is greater than or equal to the size threshold indicated by the fragmentation conditions, the system determines that the file attribute information meets the fragmentation conditions. When the file type is inconsistent with the preset type or the file size is less than the size threshold, the system determines that the file attribute information does not meet the fragmentation conditions. When the file attribute information meets the fragmentation conditions, the original file is fragmented and encrypted, and the fragmented and encrypted original file is stored. When the file attribute information does not meet the fragmentation conditions, the original file is encrypted as a whole to obtain the overall content identifier of the original file, and the overall content identifier is stored to complete the storage of the original file.

3. The method according to claim 2, characterized in that, The step of fragmenting and encrypting the original file, and storing the fragmented and encrypted original file, includes: The original file is divided into multiple file fragments according to a preset file fragmentation standard. Each file segment is encrypted to generate a segment content identifier corresponding to each file segment, resulting in multiple segment content identifiers; Using the multiple fragment content identifiers, an identifier index tree is constructed and stored to complete the fragmentation and encryption processing of the original file.

4. The method according to claim 1, characterized in that, When a file operation request for the original file is received from another user on another blockchain, the dynamic watermark contract is invoked to add a dynamic watermark to the original file, and the original file with the added dynamic watermark is used to respond to the file operation request, including: Receive the file operation request and identify the file operation request; When the file operation request is identified as indicating that the original file should be downloaded, the permissions of the other users are verified. If the verification is successful, the dynamic watermark contract is invoked to add explicit and implicit watermarks as dynamic watermarks to the original file so that the other users can download it. When the file operation request is identified and determined to indicate that the original file should be forwarded, the recipient of the forwarding operation is determined. Referring to the recipient's recipient information, the dynamic watermark contract is invoked to update the dynamic watermark currently added to the original file. The updated original file is then forwarded to the recipient, and the file flow path of this forwarding is recorded.

5. The method according to claim 4, characterized in that, The step of calling the dynamic watermark contract to add explicit and implicit watermarks as dynamic watermarks to the original file so that other users can download it includes: Obtain the user identifier and user geocode of the other users, determine the file hash value of the original file, and construct a first timestamp with reference to the time point when the file operation request was received; The user identifier and the first timestamp are combined to form the first explicit text, and the dynamic watermark contract is invoked so that the dynamic watermark contract uses the first explicit text to add an explicit watermark to the original file. Simultaneously, the dynamic watermark contract is invoked, and the file hash value and the user geocode are processed using the invisible watermark embedding technology to add an invisible watermark to the original file, so that the explicit watermark and the invisible watermark can be used as the dynamic watermark added to the original file. The file formats associated with other blockchains are queried, and the original file after adding the dynamic watermark is converted to the correct format so that other users can download it.

6. The method according to claim 4, characterized in that, The step of referencing the recipient's information and invoking the dynamic watermark contract to update the currently added dynamic watermark on the original file includes: Based on the recipient information, the recipient identifier and recipient geocode are determined, the file hash value of the original file is determined, and a second timestamp is constructed with reference to the time point when the file operation request was received; The recipient identifier and the second timestamp are combined to form a second explicit text, and the dynamic watermark contract is invoked so that the dynamic watermark contract updates the explicit watermark in the dynamic watermark currently added to the original file using the second explicit text. Simultaneously, the dynamic watermark contract is invoked, and the hidden watermark embedding technology is used to process the file hash value and the recipient geocode, updating the hidden watermark in the dynamic watermark currently added to the original file, so as to complete the update of the dynamic watermark currently added to the original file.

7. The method according to claim 1, characterized in that, The step of generating a file processing log based on the dynamic watermark and the file operation request, and storing the file processing log in the traceability evidence chain, includes: Obtain the identifier of the private chain as the source chain identifier, and obtain the identifiers of the other blockchains as the target chain identifier; Based on the signatures of the original file by other users during authentication, an aggregate signature is generated. The dynamic watermark, the source chain identifier, the target chain identifier, and the aggregate signature are then organized to generate the file processing log. The file processing log is then transmitted to the tracing evidence chain so that the tracing evidence chain stores the file processing log in the tracing chain database. When the source tracing requirement is detected, the source tracing evidence chain invokes the audit contract to initiate the source tracing process, generates an evidence package based on the file processing log, and transmits the evidence package to the regulatory agency so that the regulatory agency can refer to the evidence package for source tracing processing.

8. A document processing device based on blockchain and dynamic watermarking, characterized in that, The device is applied to a private blockchain system and includes: An encryption module is used to receive an original file sent by a user, encrypt the original file, and store the processed original file. The watermarking module is used to call the dynamic watermarking contract to add a dynamic watermark to the original file when it receives a file operation request initiated by other users on other blockchains for the original file, and to respond to the file operation request using the original file with the added dynamic watermark. The log storage module is used to generate a file processing log based on the dynamic watermark and the file operation request, store the file processing log in the traceability evidence chain, and use the file processing log to provide traceability operations for file processing when a traceability requirement arises.

9. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the file processing method based on blockchain and dynamic watermarking as described in any one of claims 1 to 7.

10. A storage medium, wherein the computer-readable storage medium stores a computer program, characterized in that, When the computer program is executed by the processor, it implements the steps of the file processing method based on blockchain and dynamic watermarking as described in any one of claims 1 to 7.

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