Bidding document fine-grained privacy protection method and system based on smart contract

Abstract

The invention discloses a bidding document fine-grained privacy protection method and system based on an intelligent contract, and relates to the technical field of information security. S1, a bidding demand is published; s2, a bidder applies for public and private keys; s3, the bidder prepares bidding content; s4, the bidder deploys an intelligent contract; s5, the bidding person decrypts the bidding file; s6, a ciphertext bidding comparison protocol; according to the method, the bidding document is encrypted by using the Paillier homomorphic encryption algorithm, and any bidder and tenderer form a two-party calculation environment, so that any bidder and tenderer can perform homomorphic calculation on the encrypted bidding document; an encrypted bidding file timing decryption and bidding price privacy comparison mechanism is established through cooperation of an intelligent contract and a threshold Paillier; according to the method, the intelligent contract and the threshold Paillier are adopted at the same time, the time when the bid invitation person obtains a certain part of private keys of any bidder is controlled through the runnable intelligent contract, and then it is ensured that the bid invitation person cannot obtain the decrypted bidding file of the bidder before the specified time.

Description

Technical Field

[0001] The present invention relates to the field of information security technology, and in particular to a fine-grained privacy protection method and system for bidding documents based on smart contracts. Background Art

[0002] In the bidding process, the privacy protection of bidding documents is of vital importance. Existing bidding document encryption protection schemes, such as blockchain technology or encryption technology, can provide certain protection, but there are still some defects. Although blockchain technology can record all key steps in the bidding process and ensure the transparency and traceability of data, it may also lead to excessive disclosure of sensitive information involved in the bidding process, affecting commercial privacy. In addition, encryption technology can protect the bidder's private data from being accessed or read by unauthorized personnel, prevent the leakage of sensitive information, and ensure that only the owner of the data has the right to access and decrypt the information. However, the existing encryption algorithm needs to frequently update the public and private keys to ensure encryption security, and cannot support bidding data encryption operations, which increases the time and communication overhead of the operation, and it is difficult to ensure the privacy security of the bidding documents. In summary, the existing bid document privacy protection scheme has the following problems: 1) While ensuring data transparency and traceability, blockchain technology may lead to excessive disclosure of sensitive information, increase the risk of commercial privacy leakage in the bidding process, and fail to effectively protect the bidder's business secrets, resulting in poor practicality; 2) There is a problem of insufficient privacy protection capabilities. Although the existing encryption technology can protect the bidder's privacy data, it requires frequent updates of public and private keys to maintain the security of encryption; 3) At the same time, the existing encryption algorithm is difficult to support the operation of encrypted data, resulting in increased computing time and communication overhead, and overall low efficiency. Therefore, it is necessary to explore new technical solutions to further strengthen the privacy protection of bid documents and ensure that the bidder's business secrets and competitive advantages are effectively protected. Therefore, the present invention is designed for the privacy protection of bid documents before the bid opening during bidding, and proposes a fine-grained privacy protection method and system for bid documents based on smart contracts.

[0003] The above information disclosed in this Background section is only for enhancement of understanding of the background of the present disclosure and therefore it may contain information that does not constitute the prior art that is already known to one of ordinary skill in the art. Summary of the invention

[0004] The purpose of the present invention is to provide a fine-grained privacy protection method and system for bidding documents based on smart contracts to solve the problems in the above-mentioned background technology.

[0005] In order to achieve the above object, the present invention provides the following technical solution: a fine-grained privacy protection method and system for bidding documents based on smart contracts, comprising the following steps: S1. Release the bidding requirements. The tenderer releases the encrypted bidding requirements through the blockchain platform and sets the bidding deadline; S2. The bidder applies for public and private keys. The bidder generates a public key through the platform for encrypting the bidding documents, and a private key for decrypting and signing the documents; S3. The bidder prepares the bidding content. The bidder prepares the bidding documents and encrypts the contents to ensure secure transmission; S4. The bidder deploys a smart contract. The bidder deploys a smart contract through the blockchain and sets the decryption time of the bidding documents; S5. The tenderer decrypts the bidding documents. After the bidding deadline, the tenderer uses the private key to decrypt the bidding documents and verify their integrity. S6. Ciphertext bidding comparison protocol, which encrypts and compares bid prices through smart contracts to ensure the fairness and privacy of the bidding process.

[0006] Preferably, in S1, the specific steps are as follows: the tenderer publishes the tender requirements through a decentralized blockchain platform, wherein the tender requirements must include the bid opening time. , which is the deadline for submission of bidding documents; all bidding documents must be submitted through designated channels before the deadline; after the bidding documents are successfully submitted, the smart contract automatically generates submission confirmation information and sends it to the bidder to ensure that the bidding documents have been received and cannot be tampered with.

[0007] Preferably, in S2, the specific steps are as follows: the bidder of the tender demand issued by the tenderer applies for the Paillier public and private key from the public key infrastructure PKI ; The Paillier public and private keys applied by each bidder to PKI are consistent; Bidders who are willing to participate in the bidding split the Paillier private key into two parts of the private key and , the split private keys of each bidder are different from each other; Among them, Paillier is a threshold Paillier cryptosystem; the Paillier generation steps are: Key generation: Randomly generate two strong prime numbers p and q of k bits, that is, p=2p'+1, q=2q'+1, where p' and q' are large prime numbers, calculate N=p·q and the greatest common divisor λ of p-1 and q-1, and calculate the inverse element μ of λ modulo N; output the public key pk=(g, N) and the private key sk=(λ, N), where g=N+1; the λ in the private key is split into λ1 and λ2, where λ1 is a random number of 80-112 bits, and λ2=λ·μ-λ1; Encryption: Given a message m, m is required to be a natural number not exceeding N. Encrypt m by calculating [m] = (m + m·N)·rN, where r is a positive integer not less than 112 bits and not exceeding N. Decryption: Given the ciphertext [m] of message m, decryption is done by calculating m=([m]λmodN2-1) / N; Partial decryption: Partial decryption takes a partial private key and encrypted ciphertext as input and calculates [m]λimodN2, where i=1 or 2; Threshold decryption: Threshold decryption takes two partially decrypted ciphertexts as input and obtains the final message m by calculating ([m]λ1modN2·[m]λ2modN2modN2-1) / N; Digital signature generation process: Hash calculation: Perform hash calculation on the message M to obtain the hash value H(M) of the message. , where Hash is a hash function; Signature generation: Use the private key sk to sign the hash value H(M) to obtain the signature S , where Sign is the signature function; Digital signature verification process: Hash calculation: Perform hash calculation on the message M to obtain the hash value H(M) of the message: ; Signature Verification: Use the public key pk to verify the signature S and whether it matches the hash value H(M);

[0008] If the verification result is True, it means the signature is valid and the message has not been tampered with; If False, the signature is invalid and the message may have been tampered with or the signature does not match.

[0009] Preferably, in S3, the specific steps are as follows: After the bidder has prepared the bidding documents, use the public key generated in S2 Encrypted bidding documents : ; Using one of the private keys Partially decrypt the encrypted bidding documents: , except for encrypted quotes Besides; The bidder chooses another partial private key , and use its private key to sign this part of the private key: ; The bidder will encrypt the bid , partially decrypted bidding documents 、Paillier public key And the signature of part of the private key It is sent to the tenderer as the bid content of the bidder; the bidder sends his signature to the tenderer, and the tenderer needs to submit the same signature to the smart contract during the subsequent bid opening to obtain the corresponding private key.

[0010] Preferably, in S4, the specific steps are as follows: any bidder deploys a smart contract on any blockchain that supports smart contracts, and the smart contract performs the following operations: back, If a bidder submits the signature of part of the private key in S3 to the smart contract , the smart contract performs the signature verification operation of the bidder: , where r is 0 or 1, 0 means verification failed, 1 means verification passed, If the verification is successful, the smart contract will transfer part of the private key in step 3 Send the tenderer; If the verification fails, it will not be sent.

[0011] Preferably, in S5, the specific steps are as follows: In S5, the specific steps are as follows: In the bid opening module, obtain a part of the private key of a bidder The bidder first uses this part of the private key The encrypted bidding documents provided by this bidder Partial decryption , and then use the decryption calculation to obtain the partial decrypted ciphertext And the partial decrypted ciphertext provided by this policyholder Perform the threshold decryption operation to obtain the final decrypted bidding document. The formula is as follows: .

[0012] Preferably, in S6, the specific steps are as follows: In S5, the specific steps are as follows: In the bid opening module, the tenderer needs to perform a secure comparison of all bidders' quotations under ciphertext, so as to ensure the fairness and justice of the entire bidding process and not disclose the bidders' privacy data; thus, a secure comparison protocol for ciphertext quotations is derived: Input: Tenderer's ciphertext quotation , .

[0013] Output: The tenderer obtains , where if ,but On the contrary, if ,but ; Calculation by the tenderer: The bidder tosses a coin to generate a random , when hour, and ; when Time, meter and ,in are two random numbers that satisfy and , ; calculate ; Will Sent to bidders; Bidder calculation: , ; when ,at this time ; when ,at this time ; Will Send to the tenderer; The tenderer calculates and compares the results : when hour, ; when hour, .

[0014] Preferably, it includes a blockchain platform module, a key management module, a bidding document encryption module, a smart contract module, a blockchain platform module, a file decryption module and a bidding comparison module; Used to publish encrypted bidding requirements and ensure the transparency and non-tamperability of bidding information; Key management module, used to generate public-private key pairs for bidders and tenderers, the public key is used to encrypt bidding documents, and the private key is used to sign and decrypt documents; Bidding document encryption module, used to encrypt bidding documents prepared by bidders to ensure the secure transmission of bidding documents; Smart contract module, used to deploy smart contracts through blockchain, set the decryption time of bidding documents, and automatically execute the bidding process; File decryption module, used by the tenderer to use the private key to decrypt the bidding documents after the bidding deadline, and verify their integrity and authenticity; Bidding comparison module, used to execute the ciphertext bidding comparison protocol through smart contracts, encrypt and compare the bidders' quotations, and ensure the fairness and privacy of the bidding process.

[0015] Preferably, the key management module and the bidding document encryption module include: A public key generation module is used to generate a unique bidder public key, which is used by the bidder to encrypt the content of the bid document to ensure that the bid document remains private and secure during transmission; The private key generation module is used to generate a unique bidder private key, which is held by the bidder and used to digitally sign the bidding document to ensure the authenticity of the document source and to decrypt the encrypted file; The bidding document encryption processing module uses the generated public key to encrypt the bidding document before submission, ensuring that the document will not be obtained or tampered with by unauthorized parties during transmission; The public and private key management module is used to manage the public and private key pairs of bidders and tenderers, ensure the safe storage of the generated public and private key pairs throughout the bidding process, prevent key leakage or tampering, and ensure data security.

[0016] Preferably, the smart contract module and the bidding comparison module include: The bidding document decryption time setting module sets the decryption time of the bidding document through the smart contract to ensure that the bidding document can be automatically decrypted at the scheduled time after the bidding deadline so that the tenderer can view the document content; The digital signature verification module verifies the bidding documents by using the public key provided by the tenderer to ensure that the bidding documents have not been tampered with during transmission and to verify the authenticity and integrity of the bidding documents; The encrypted quotation comparison module is used to automatically compare and analyze encrypted bid quotations through smart contracts, ensuring that bidders' quotations remain encrypted during the comparison process, preventing price leakage and ensuring bidding fairness; The bidding process recording module records the entire bidding process through blockchain, including the submission time of the bid, the encrypted comparison results, and the generation of the final bidding results, ensuring the transparency of the bidding process while protecting the bidders' privacy data.

[0017] In the above technical scheme, the technical effects and advantages provided by the present invention are: first, a bidding key management mechanism based on threshold Paillier. In the bidding system designed by the present invention, bidders generate their own Paillier public and private keys through the public key infrastructure, and split their private keys into two threshold private keys. Compared with the previous bidding system, the key management of the present invention is generated by the bidders themselves, avoiding frequent key updates. Secondly, the encrypted bidding document management technology supported by homomorphic computing. The present invention encrypts the bidding documents with the Paillier homomorphic encryption algorithm, and makes any bidder and the tenderer constitute a two-party computing environment, so that any bidder and the tenderer can perform homomorphic computing on the encrypted bidding documents. Finally, the privacy protection of encrypted bidding documents coordinated by smart contracts and threshold Paillier. In the present invention, in order to ensure that the tenderer cannot obtain the bidding documents before the bid opening and thus protect the privacy of the bidding documents, the present invention simultaneously adopts smart contracts and threshold Paillier, and controls the time when the tenderer obtains a part of the private key of any bidder through an executable smart contract, thereby ensuring that the tenderer cannot obtain the encrypted bidding documents of the bidder before the specified time. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present application and the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0019] Figure 1 This is a step diagram of the privacy protection method of the invention.

[0020] Figure 2 This is a schematic diagram of the privacy protection method module of the present invention.

[0021] Figure 3 The following is a business flow chart of the invention.

[0022] Figure 4 This is a flow chart of the privacy protection method of the invention. DETAILED DESCRIPTION

[0023] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of forms and should not be construed as limited to the examples set forth herein; rather, these example embodiments are provided so that the description of the present disclosure will be more comprehensive and complete, and the concept of the example embodiments will be fully conveyed to those skilled in the art.

[0024] The present invention provides Figures 1 to 3A bidding document fine-grained privacy protection method and system based on smart contracts is shown, characterized in that it includes the following steps: S1. Release the bidding requirements. The tenderer releases the encrypted bidding requirements through the blockchain platform and sets the bidding deadline; S2. The bidder applies for public and private keys. The bidder generates a public key through the platform for encrypting the bidding documents, and a private key for decrypting and signing the documents; S3. The bidder prepares the bidding content. The bidder prepares the bidding documents and encrypts the contents to ensure secure transmission; S4. The bidder deploys a smart contract. The bidder deploys a smart contract through the blockchain and sets the decryption time of the bidding documents; S5. The tenderer decrypts the bidding documents. After the bidding deadline, the tenderer uses the private key to decrypt the bidding documents and verify their integrity. S6. Ciphertext bidding comparison protocol, which encrypts and compares bid prices through smart contracts to ensure the fairness and privacy of the bidding process.

[0025] In S1, the specific steps are as follows: The tenderer publishes the tender requirements through a decentralized blockchain platform, which must include the bid opening time. , which is the deadline for submission of bid documents; all bid documents must be submitted through designated channels before the deadline; after the bid documents are successfully submitted, the smart contract automatically generates submission confirmation information and sends it to the bidder to ensure that the bid documents have been received and cannot be tampered with; publishing bidding requirements is the first step in the bidding process and the basis for ensuring transparency and fair competition in bidding. The tenderer publishes bidding requirements through a decentralized blockchain platform to provide project information to potential bidders. This information usually includes the overall description of the project, technical requirements, scope of work, budget, delivery time, evaluation criteria, etc. These detailed descriptions help bidders fully understand the needs of the project and assess whether they have the ability to execute the project. In this process, the tenderer needs to pay special attention to clearly expressing the core requirements of the project to avoid misunderstandings of the project content by bidders. For example, the tenderer may detail technical specifications, compliance requirements, specific resources required for the project, and the expected final results. This ensures that bidders can accurately grasp the scope and objectives of the project when preparing bidding documents.

[0026] In addition, the tenderer needs to specify the deadline for document submission, i.e. the bid opening time, in the tender notice. This is an important mechanism to ensure the fairness of the tender process, because after this date, all bid documents will be locked and cannot be modified. The tamper-proof nature of blockchain technology plays a key role in this regard. All submission and modification records of bid documents will be transparently recorded on the blockchain to ensure the fairness of the subsequent process. In order to ensure the security of data, the tenderer also usually requires the bidder to encrypt the bid documents submitted by the tenderer. The specific requirements for encryption, such as the type of encryption algorithm used, the key length, and the method of data submission, will be detailed in the notice. This not only helps to improve the security of the bid documents, but also prevents the documents from being maliciously stolen or tampered with during transmission. The tenderer needs to clearly require the format of the bid documents and the encryption standard to ensure that all bidders follow the same technical specifications, so as to avoid affecting the fairness of the evaluation due to inconsistent file formats or encryption methods.

[0027] In addition, the announcement should also include a confirmation mechanism after the bid documents are submitted. After each bidder successfully submits the documents, the system will automatically generate a submission confirmation message to ensure that all parties know that their bid documents have been received and safely stored on the blockchain. In this way, both the tenderer and the bidder can be sure that the documents have been successfully submitted and that the documents will not be modified or lost before the bid opening time arrives. Another important content is the qualification requirements. The tenderer will specify the qualifications or conditions that the bidder must have, such as experience in previous projects, financial status, etc. Qualification requirements can ensure that only qualified bidders participate in the bidding, thereby improving the quality and success rate of the project. Usually, the tenderer will list specific evaluation criteria in the announcement, detailing the importance of technical solutions, quotations, project management capabilities, etc., which will help bidders to optimize their bid content in a targeted manner and increase the possibility of winning the bid.

[0028] Finally, when issuing tender requirements, it is also necessary to ensure that the tender notice contains a communication mechanism. The tenderer should provide contact information or set up an inquiry window in the notice so that bidders can consult on unclear points when preparing their bid documents. Usually this communication mechanism will be open within a specific time window to ensure that all bidders have enough time to understand the tender requirements and clarify issues. This communication can not only help bidders prepare documents better, but also help reduce misunderstandings in the bidding process and avoid bid failures due to information asymmetry. In the modern bidding process, blockchain technology provides transparency and immutability for the entire communication process. All supplementary information or clarification issues will be recorded on the blockchain to ensure that all bidders have access to the same information and opportunities.

[0029] In S2, the specific steps are as follows: Bidders of the tender requirements issued by the tenderer apply for Paillier public and private keys from the public key infrastructure PKI ; The Paillier public and private keys applied by each bidder to PKI are consistent; Bidders who are willing to participate in the bidding split the Paillier private key into two parts of the private key and , the split private keys of each bidder are different from each other; Among them, Paillier is a threshold Paillier cryptosystem; the Paillier generation steps are: Key generation: Randomly generate two strong prime numbers p and q of k bits, that is, p=2p'+1, q=2q'+1, where p' and q' are large prime numbers, calculate N=p·q and the greatest common divisor λ of p-1 and q-1, and calculate the inverse element μ of λ modulo N; output the public key pk=(g, N) and the private key sk=(λ, N), where g=N+1; the λ in the private key is split into λ1 and λ2, where λ1 is a random number of 80-112 bits, and λ2=λ·μ-λ1; Encryption: Given a message m, m is required to be a natural number not exceeding N. Encrypt m by calculating [m] = (m + m·N)·rN, where r is a positive integer not less than 112 bits and not exceeding N. Decryption: Given the ciphertext [m] of message m, decryption is done by calculating m=([m]λmodN2-1) / N; Partial decryption: Partial decryption takes a partial private key and encrypted ciphertext as input and calculates [m]λimodN2, where i=1 or 2; Threshold decryption: Threshold decryption takes two partially decrypted ciphertexts as input and obtains the final message m by calculating ([m]λ1modN2·[m]λ2modN2modN2-1) / N; Digital signature generation process: Hash calculation: Perform hash calculation on the message M to obtain the hash value H(M) of the message. , where Hash is a hash function; Signature generation: Use the private key sk to sign the hash value H(M) to obtain the signature S , where Sign is the signature function; Digital signature verification process: Hash calculation: Perform hash calculation on the message M to obtain the hash value H(M) of the message: ; Signature Verification: Use the public key pk to verify the signature S and whether it matches the hash value H(M);

[0030] If the verification result is True, it means the signature is valid and the message has not been tampered with; If it is False, it means that the signature is invalid, the message may be tampered with or the signature does not match; the bidder's application for public and private keys is an important step to ensure the privacy and security of the bidding process data. In the blockchain system, the bidder applies for a pair of public and private keys through the public key infrastructure (PKI) to encrypt its bidding documents and signature data. This is very important for the role of public and private keys. The public key is used to encrypt the bidding documents, while the private key is used to sign and decrypt the documents to ensure the privacy and non-tamperability of the documents. Bidders usually apply for public and private keys through a trusted third-party organization, and this process is automated. The applied public key can be made public to other relevant parties, especially the tenderer, for the processing of encrypted data, while the private key is kept by the bidder himself for signing documents and subsequent decryption operations. The asymmetric encryption characteristics of public and private keys make it impossible for anyone to decrypt or read the content even if the bidding documents are intercepted during transmission. Only the person holding the corresponding private key can decrypt the data.

[0031] The process of applying for public and private keys is not only a necessary technical step, but also an important part of ensuring that the bidding process meets compliance requirements. After submitting a key application to the PKI, the bidder will receive a unique key pair generated by the system. These key pairs are generated by modern encryption algorithms (such as RSA or ECC), ensuring the security of the bidding documents. The main function of the public key is to encrypt the bidding documents, which means that the documents written by the bidder can only be decrypted and viewed by the tenderer who holds the corresponding private key after encryption. At the same time, the bidder needs to use the private key to digitally sign the document. The signature is an important means to verify the integrity and authenticity of the document. By verifying the bidder's signature, the tenderer can ensure that the document has not been tampered with during transmission and that the document is indeed submitted by the bidder. This encryption and signing mechanism not only protects the confidentiality of the bidding documents, but also prevents malicious bidding or document forgery.

[0032] The management of private keys is a key link in the entire process. Bidders must ensure the safe storage and use of private keys. Usually, bidders will use security devices such as hardware security modules (HSM) that are specifically used to store keys to prevent private keys from being leaked or abused. The leakage of private keys may cause the bidding documents to be tampered with or forged by others, which will seriously affect the bidder's bidding opportunities. Under the premise of security, bidders use private keys to sign the bidding documents and encrypt their core content. The correct use of private keys is the basis for ensuring that the documents are not modified during transmission. It can ensure that the bidding documents remain highly secure and unchangeable even if they are intercepted or stored in an untrusted environment. With the support of blockchain technology, the public keys of all bidders will be recorded in the blockchain to ensure that the release of public keys is open and transparent. This transparency ensures that all bidding documents can be verified through public keys, which improves the credibility of the entire bidding process.

[0033] In addition, the use of public and private keys not only ensures the security of bidding documents, but also improves the legitimacy and compliance of the entire bidding process. As a legally recognized electronic certificate, digital signatures can serve as effective evidence in contract disputes or legal disputes to prove the source and integrity of bidding documents. Therefore, the bidder's application for public and private keys is not only a technical operation, but also a legal protection measure. Through this technical means, bidders can be sure that their data is safe when submitting documents, and the tenderer can also verify the authenticity of the documents, thereby ensuring the fairness and transparency of the entire bidding process.

[0034] In S3, the specific steps are as follows: After the bidder has prepared the bid documents, he uses the public key generated in S2 Encrypted bidding documents : ; Using one of the private keys Partially decrypt the encrypted bidding documents: , except for encrypted quotes Besides; The bidder chooses another partial private key , and use its private key to sign this part of the private key: ; The bidder will encrypt the bid , partially decrypted bidding documents 、Paillier public key And the signature of part of the private key The bidder sends the signature to the tenderer, and the tenderer needs to submit the same signature to the smart contract to obtain the corresponding private key when the bid is opened. After applying for the public and private keys, the bidder enters the most critical link, that is, preparing the bid content. The preparation of the bid content is not only the writing of the technical plan, but also the preparation of commercial quotations, project plans and related qualification documents. The bidder first needs to have an in-depth understanding of the requirements in the tender notice and write a detailed technical plan that meets the project goals based on these requirements. This technical plan needs to cover the background understanding of the project, the specific methods of technical implementation, the required resources and the project execution plan. For example, in software development projects, bidders may need to describe the development framework, technology stack, staffing, time nodes and other details to ensure that the tenderer can fully understand the bidder's understanding and execution capabilities of the project. The technical plan is not only a statement of the project, but also should demonstrate the bidder's professional ability and technical strength. Especially when the tender project has complex technical requirements, the bidder needs to demonstrate its unique technical solution capabilities through its plan.

[0035] At the same time, commercial quotation is also a crucial part of the preparation of bidding content. The quotation not only includes the total cost, but also needs to break down the specific cost of each work. Especially in large projects, a detailed quotation structure can allow the tenderer to better understand the cost allocation. Bidders should formulate reasonable quotations based on the scale, difficulty, required resources and their own profit expectations of the project. Reasonable quotations are crucial in competition. Too high quotations may lead to the loss of the opportunity to win the bid, while too low quotations may affect the profitability of bidders. In many cases, bidders are also required to provide successful cases of similar projects to prove their execution capabilities and successful experience in similar projects. These cases not only increase the credibility of the bid, but also demonstrate the bidder's project management and technical delivery capabilities. In addition, the preparation of the bid documents also needs to include the company's qualification certificate, the professional qualifications of the team members, and the project management method to meet the tenderer's requirements for qualified suppliers of the project. During the preparation process, bidders also need to ensure that the various parts of the bid documents are clearly structured and logically reasonable, and can fully demonstrate their ability to execute the project.

[0036] After the bidding documents are prepared, the bidder needs to encrypt all the contents. Using the public key applied for previously, the bidder encrypts all the bidding documents to ensure that the documents will not be stolen or tampered with by the outside during the transmission and storage process. The encryption operation not only protects the privacy of the documents, but also ensures that the documents maintain integrity during the transmission process. Even if the documents are intercepted, unauthorized persons cannot decrypt the contents. This operation is usually completed through automated encryption tools. Bidders only need to upload the documents to the blockchain platform, and the platform will automatically encrypt the documents according to the public key. At the same time, bidders also need to use private keys to digitally sign the bidding documents. The purpose of the signature is to ensure the source and authenticity of the documents. After receiving the documents, the tenderer will confirm the integrity of the documents by verifying the bidder's signature and ensure that the documents have not been tampered with during the transmission process. This process not only ensures the privacy of the documents, but also improves the transparency and trust of the bidding process.

[0037] Before submitting the documents, bidders need to conduct multiple checks to ensure the accuracy and consistency of all information. Once the documents are submitted to the blockchain platform, they cannot be modified. Therefore, bidders need to ensure the correctness and completeness of the technical solutions, quotations, qualification documents, etc. before submission. In some cases, bidders may use the professional consulting services of a third party to optimize their bid documents to ensure that the documents not only meet the bidding requirements but also stand out from the competition. Finally, the bid documents are uploaded through the blockchain platform. Once the documents are submitted, the system will automatically generate a submission timestamp and record it on the blockchain. In this way, all submitted operations can be transparently tracked and verified to ensure the fairness and immutability of the bidding process. After the documents are submitted, bidders can check the submission status of their documents through the platform and wait for the bid opening time to arrive.

[0038] In S4, the specific steps are as follows: Any bidder deploys a smart contract on any blockchain that supports smart contracts. The smart contract performs the following operations: back, If a bidder submits the signature of part of the private key in S3 to the smart contract , the smart contract performs the signature verification operation of the bidder: , where r is 0 or 1, 0 means verification failed, 1 means verification passed, If the verification is successful, the smart contract will transfer part of the private key in step 3 Send the tenderer; If the verification fails, it will not be sent; after the bid documents are prepared and encrypted, the bidder needs to deploy the smart contract through the blockchain platform. The deployment of smart contracts is a key link in the automation and transparency of the bidding process. It ensures that every operation can be automatically executed on the blockchain through a series of preset rules and conditions. The deployment of smart contracts usually occurs before the bid documents are submitted, and the bidder sets the contract content according to the requirements of the blockchain platform. The main function of the contract is to ensure that all operations can be executed according to the specified time and conditions during the bidding process without manual intervention. The smart contract contains the encrypted information of the bid documents, submission time, signature verification rules, etc., and once deployed, all operations will be automatically triggered according to the set conditions. For example, the smart contract can pre-set the submission time window of the bid documents, and automatically lock the bid when the bid opening time arrives to prevent the bidder from submitting or modifying the documents after the deadline.

[0039] Another important function of deploying smart contracts is to ensure the verification and processing of bidding documents. Smart contracts can automatically check the encryption format of bidding documents, the validity of signatures, and the integrity of documents. For any documents that do not meet the requirements, smart contracts will automatically refuse to receive them and notify bidders to make corrections. At the same time, smart contracts can also set up multiple verification mechanisms to ensure that every step of the bidding documents after submission meets security and regulatory requirements. Through smart contracts, bidders can ensure that the documents will not be tampered with or leaked after submission, and all operation records will be transparently stored on the blockchain to form an audit record that cannot be tampered with. The application of blockchain technology makes every submitted document and every performed operation traceable, thereby ensuring the fairness and transparency of the entire bidding process.

[0040] The automated execution of smart contracts also simplifies many complex processes. In the past, a lot of manual operations were required during the bidding process to verify the integrity of documents, the accuracy of time, etc., but with smart contracts, these operations have become highly automated. For example, smart contracts can automatically decrypt bidding documents at a preset time, or compare bidders' quotations according to set rules. These operations do not require human intervention. Smart contracts execute processes according to code to ensure that all bidders are subject to the same rules, avoiding unfair competition caused by human factors. By deploying smart contracts, bidders not only simplify the entire bidding process, but also improve the security and transparency of data through blockchain technology. In addition, the deployment of smart contracts can also help bidders reduce operating costs and improve efficiency, because all operations are executed automatically without additional human intervention.

[0041] During the execution of the smart contract, bidders can also view the status of document submission and the execution of the smart contract in real time through the blockchain platform. This transparency not only improves the trust of bidders, but also enhances the openness and traceability of the entire bidding process. The deployment of smart contracts also provides a basis for the subsequent decryption of bidding documents and bidding comparison. When the bid opening time arrives, the smart contract will automatically unlock and start the decryption program to send the encrypted bidding documents to the tenderer. In this process, all operations are recorded on the blockchain, ensuring that both bidders and tenderers can view the entire process of the operation, thereby improving the credibility and efficiency of the bidding process. By deploying smart contracts, bidders ensure the automated execution of the entire process, while laying a solid foundation for the subsequent decryption and bidding process.

[0042] In S5, the specific steps are as follows: In the bid opening module, obtain a part of the private key of a bidder The bidder first uses this part of the private key The encrypted bidding documents provided by this bidder Partial decryption , and then use the decryption calculation to obtain the partial decrypted ciphertext And the partial decrypted ciphertext provided by this policyholder Perform the threshold decryption operation to obtain the final decrypted bidding document. The formula is as follows: ; It is worth noting that in S2, bidders only need to apply for public and private keys from PKI once, and they can be used for multiple different bids. Specifically, when bidding for other projects again, bidders only need to split the private key sk into two parts in a new way. and There are many ways to split the bid. Repeating steps 3-5 can complete the new bidding process, thus avoiding the frequent update of public and private keys. When the bid opening time TTT arrives, the tenderer needs to start decrypting the bid documents submitted by all bidders through the blockchain platform. This is a crucial step in the entire bidding process, because the decrypted bid documents will be used as the basis for evaluating and selecting the successful bidder. During the submission stage of the bid documents, all documents have been encrypted by the bidder, which means that the tenderer needs to use part of the private key submitted by the bidder to decrypt these documents to read the contents. The decryption process ensures the privacy and security of the bid documents. During the bidding process, no third party can obtain the detailed information of these documents except the bidder and the tenderer. The decryption process is usually automatically triggered by a smart contract, which will unlock the file within the specified time according to the pre-set rules and transmit the encrypted data to the tenderer.

[0043] In the decryption process, the immutability of blockchain technology plays a vital role. The decryption operations of all bidding documents will be recorded on the blockchain, ensuring that each step of the operation can be traced and no one can tamper with the bidding documents. The smart contract will automatically obtain some private keys provided by the bidders and use these private keys to decrypt the core content of the documents, such as quotations, technical solutions and other important information. This process ensures that the tenderer can read all bidding documents smoothly and conduct a detailed review and comparison of each bidder's proposal. The tenderer's operation of decrypting files must also be carried out strictly in accordance with the rules of the blockchain platform. Any decryption operation that does not meet the specifications will be rejected by the system to prevent illegal acquisition of data or operational errors.

[0044] The decrypted bidding documents include the bidder's technical solution, quotation, project plan and other core information. The tenderer needs to conduct a detailed evaluation of these contents to determine which bidder can provide the most competitive solution. The decrypted documents will clearly show the quotation details and technical capabilities of each bidder, which will serve as the main basis for the evaluation committee to conduct the evaluation. During the technical solution evaluation stage, the tenderer will carefully review each bidder's understanding of the project and technical solutions to ensure that the solutions provided can effectively meet the project requirements. At the same time, the quotation part is also a key factor in the evaluation process. The tenderer needs to ensure that the bidder's quotation is reasonable and competitive. Therefore, when decrypting the documents, the tenderer needs to pay special attention to the technical details and quotation parts of the documents to ensure that each bidder's solution meets the requirements set out in the initial tender notice.

[0045] The decrypted files will be stored on the blockchain, and the tenderer and the review committee members can view the contents of all bidding documents through the blockchain. The immutability of the blockchain ensures that the decrypted files will not be modified again, and all operation records are transparently displayed on the blockchain, ensuring the fairness and transparency of the review process. During the evaluation process, the tenderer can also make further clarifications or supplementary requests to the bidder as needed to ensure that every detail in the bidding documents can be clearly answered. In addition, the tenderer can also use the smart contracts of the blockchain platform to set some automated evaluation criteria, such as automated comparison of certain key indicators (such as quotations, project duration, etc.), thereby improving the efficiency of the review.

[0046] It is worth noting that the decrypted bidding documents are not only used to evaluate technical solutions and quotations, but also involve discussions on contract terms. The bidding documents for many projects will include a preliminary draft of the contract terms, and bidders can propose amendments based on their own business strategies and project experience. During the decryption stage, the tenderer also needs to carefully review these terms to ensure the rationality and enforceability of the contract terms. In this way, the tenderer can not only select the best technical solutions and quotations during the review, but also ensure that the execution of future projects has solid legal guarantees. The process of decrypting bidding documents is a core part of the bidding process. It ensures the security and integrity of the bidding data and provides a basis for subsequent bid evaluation and contract negotiations.

[0047] In general, the process of decrypting bidding documents by the tenderer is not only technical but also strategic. On the technical level, the decryption operation needs to ensure the security and privacy of data to prevent data leakage or tampering; on the strategic level, the content of the decrypted file will directly affect the decision-making of the bid. Therefore, when decrypting bidding documents, the tenderer must ensure both the security of the process and the fairness and transparency of the evaluation.

[0048] In S6, the specific steps are as follows: In the bid opening module, the tenderer needs to perform a secure comparison of all bidders' quotations under ciphertext to ensure the fairness of the entire bidding process and not leak the bidders' privacy data; this leads to a secure comparison protocol for ciphertext quotations: Input: Tenderer's ciphertext quotation , .

[0049] Output: The tenderer obtains , where if ,but On the contrary, if ,but ; Calculation by the tenderer: The bidder tosses a coin to generate a random , when hour, and ; when Time, meter and ,in are two random numbers that satisfy and , ; calculate ; Will Sent to bidders; Bidder calculation: , ; when ,at this time ; when ,at this time ; Will Send to the tenderer; The tenderer calculates and compares the results : when hour, ; when hour, ; When all bid documents are successfully decrypted, the tenderer will enter the final critical step, which is to execute the Ciphered Bidding Comparison Protocol (CBCP). The main purpose of this protocol is to compare bids through encrypted data without revealing the bidders' bid details, and finally determine the most competitive bidder. The Ciphered Bidding Comparison Protocol is a special bidding method based on encryption algorithms and blockchain technology, which ensures that the bid information of all participants will not be leaked during the comparison process, but accurate bidding results can still be obtained. In traditional bidding, bidders' bids are public, while CBCP protects the bids through encryption technology, and only the final comparison results will be publicly displayed.

[0050] When executing the ciphertext bidding comparison protocol, the tenderer does not need to decrypt the bidder's specific quotation, but automatically performs the comparison of encrypted data through the smart contract. The smart contract will homomorphically encrypt the quotation data of each bidder according to the preset rules, and then compare these encrypted data. The advantage of this encrypted comparison is that even if competitors can see the encrypted data, they cannot infer the actual quotation of the bidder through this data. Therefore, the ciphertext bidding comparison protocol greatly enhances the privacy and fairness of the bidding process, while ensuring the accuracy of the quotation comparison.

[0051] During the ciphertext bidding process, the smart contract will automatically perform the bid comparison operation of each bidder and derive the final ranking based on the comparison results. The tenderer can view the comparison process and results in real time through the blockchain platform to ensure that all operations are transparent and fair. The role of the smart contract in this link is crucial. It is not only responsible for performing the comparison of encrypted data, but also can automatically calculate the competitiveness ranking of each bidder and generate the final winning result. During the execution process, all operation records will be transparently saved on the blockchain to ensure the immutability of the entire bidding process. This fully automated bidding comparison method reduces the possibility of manual intervention and greatly improves the efficiency and fairness of the bidding process.

[0052] Another advantage of the ciphertext bidding comparison protocol is its data security. Since all quotation data is submitted and compared in encrypted form, even the tenderer or other relevant parties cannot obtain the actual quotation information of the bidder during the comparison process. This fully encrypted comparison method ensures the privacy of quotation information during the bidding process and prevents the possibility of information leakage. In addition, the ciphertext bidding comparison protocol can also adjust parameters through smart contracts to adapt to different types of projects and bidding requirements. For example, some projects may focus more on technical solutions rather than the lowest quotation. Smart contracts can automatically adjust the comparison criteria according to preset weights to ensure that the evaluation process meets the actual needs of the project.

[0053] After the execution of the encrypted bidding comparison protocol is completed, the smart contract will automatically generate the final winning result and notify all participating bidders. The tenderer can select the winning bidder based on the execution result of the smart contract and start the subsequent contract negotiation and project execution. In this process, the encrypted bidding comparison protocol not only ensures the privacy and fairness of the bidding process, but also greatly improves the efficiency of the bidding and reduces the disputes and opacity that may arise in the traditional bidding process. All participants can view the entire bidding process through the blockchain platform to ensure that they have equal opportunities to compete in the bidding process.

[0054] In short, the Ciphertext Bidding Comparison Protocol solves the problems of price leakage and unfair competition in the traditional bidding process through the combination of encryption technology and smart contracts. It provides bidders with higher privacy protection and also provides tenderers with a more transparent and fair bidding method. With the development of blockchain technology, the Ciphertext Bidding Comparison Protocol will become an important tool in the bidding of more large-scale projects in the future, which not only ensures the efficiency and security of the bidding process, but also provides strong support for the digital transformation of the bidding industry.

[0055] It includes blockchain platform module, key management module, bidding document encryption module, smart contract module, blockchain platform module, file decryption module and bidding comparison module; Used to publish encrypted bidding requirements and ensure the transparency and immutability of bidding information; Key management module, used to generate public and private key pairs for bidders and tenderers, the public key is used to encrypt bidding documents, and the private key is used to sign and decrypt documents; Bidding document encryption module, used to encrypt the bidding documents prepared by the bidder to ensure the secure transmission of the bidding documents; Smart contract module, used to deploy smart contracts through blockchain, set the decryption time of bidding documents, and automatically execute the bidding process; File decryption module, used for the tenderer to use the private key to decrypt the bidding documents after the bidding deadline, and verify its integrity and authenticity; Bidding comparison module, used to execute the ciphertext bidding comparison protocol through smart contracts, encrypt and compare the bidders' quotations, and ensure the fairness and privacy of the bidding process; Key management module and bidding document encryption module include: A public key generation module is used to generate a unique bidder public key, which is used by the bidder to encrypt the content of the bid document to ensure that the bid document remains private and secure during transmission; The private key generation module is used to generate a unique bidder private key, which is held by the bidder and used to digitally sign the bidding document to ensure the authenticity of the document source and to decrypt the encrypted file; The bidding document encryption processing module uses the generated public key to encrypt the bidding document before submission, ensuring that the document will not be obtained or tampered with by unauthorized parties during transmission; The public and private key management module is used to manage the public and private key pairs of bidders and tenderers, ensure the safe storage of the generated public and private key pairs throughout the bidding process, prevent key leakage or tampering, and ensure data security; The smart contract module and bidding comparison module include: The bidding document decryption time setting module sets the decryption time of the bidding document through the smart contract to ensure that the bidding document can be automatically decrypted at the scheduled time after the bidding deadline so that the tenderer can view the document content; The digital signature verification module verifies the bidding documents by using the public key provided by the tenderer to ensure that the bidding documents have not been tampered with during transmission and to verify the authenticity and integrity of the bidding documents; The encrypted quotation comparison module is used to automatically compare and analyze encrypted bid quotations through smart contracts, ensuring that bidders' quotations remain encrypted during the comparison process, preventing price leakage and ensuring bidding fairness; The bidding process recording module records the entire bidding process through blockchain, including the submission time of the bid, the encrypted comparison results, and the generation of the final bidding results, ensuring the transparency of the bidding process while protecting the bidders' privacy data.

[0056] First of all, in the bidding process, the key management module is one of the cores of the entire system. The key management module is responsible for generating and managing the public and private key pairs of bidders and tenderers. In the specific implementation, the key management module generates a unique public key for each bidder through the public key generation module, which is used to encrypt the bidding documents. The bidder applies for the public key through the platform, which is allocated by the smart contract on the blockchain and stored on the blockchain, making it impossible to be tampered with or forged. The bidder then uses the public key to encrypt the prepared bidding documents to ensure the security of the bidding documents during network transmission. At the same time, the key management module also generates a unique private key for each bidder through the private key generation module. The private key is held by the bidder and used to sign the bidding documents. It is used when the tenderer decrypts the bidding documents to ensure the authenticity of the source of the documents. The private key is also managed by the smart contract and ensures that it is securely protected throughout the bidding process and will not be obtained or used by unauthorized third parties.

[0057] Secondly, after the bidder prepares the bid documents through the system, the bid document encryption processing module is responsible for encrypting the documents. Once the bid documents are encrypted, they will be transmitted through the blockchain to ensure the confidentiality and non-tamperability of the documents during the transmission process. The entire process is strictly carried out in accordance with the pre-set bidding schedule, and no bid documents can be decrypted or viewed in advance after encryption. Blockchain technology is used to ensure that the records of each encrypted document are traceable and non-tamperable, thereby preventing any improper behavior before the bidding deadline. Through this combination of encryption and blockchain storage, the file data security of each bidder is guaranteed, and the transparency and fairness of the entire bidding process are improved.

[0058] The smart contract module plays a vital role in this system. Smart contracts are pre-set code programs that are automatically executed when predetermined conditions are met. Once the bid document is encrypted and submitted, the smart contract module will automatically set the decryption time of the bid document, usually after the bid deadline. The bid deadline is pre-set by the tenderer and solidified on the blockchain through smart contracts. All bidders must submit documents before the deadline. Once the deadline arrives, the smart contract will trigger the automatic decryption of the file. The tenderer can use the private key generated by the key management module to decrypt and view the content of the bid document. In this process, the digital signature verification module will also verify the signature of the decrypted bid document through the bidder's public key obtained in advance by the tenderer to ensure that the source of the document has not been tampered with or forged.

[0059] The encrypted quotation comparison module is another important part of this system. The quotation information contained in the bidding document is encrypted when submitted, and all bidders' quotations are submitted in encrypted form to ensure that price information will not be leaked during the entire bidding process. After the tenderer decrypts the file, the system automatically compares and analyzes the encrypted quotations of all bidders through smart contracts. Since each bidder's quotation is submitted in encrypted form, the smart contract will compare the bidders' quotations in encrypted form to ensure the fairness of the bidding process. In this way, the tenderer can avoid manual operation or improper intervention, and all quotation comparison processes are executed by transparent and reliable smart contracts on the blockchain, ensuring the objectivity and fairness of the entire bidding process.

[0060] Finally, the transparency and privacy of the entire bidding process are guaranteed by the bidding process recording module. Blockchain technology is used to record every step of the bidding in detail, including the submission time of the bidding documents, the comparison results of the encrypted quotations, and the final winner of the bidding. Due to the immutability of blockchain, all operation records cannot be changed or deleted, ensuring the transparency and traceability of the bidding process. This feature is particularly helpful for the tenderer or other relevant parties to review the entire bidding process after the bidding is completed, protecting the legitimate rights and interests of all parties to the bidding.

[0061] In summary, the bidding system based on blockchain technology of the present invention successfully realizes the security of bidding documents, the transparency of bidding process and the fairness of bidding process through the combination of key management, file encryption, smart contract and bidding comparison module, and has extremely high practical value and security. In practical applications, this system can not only effectively prevent the leakage of bidding documents, but also ensure the fairness and justice of bidding process, greatly improving the efficiency and transparency of bidding process.

[0062] The above description is only by way of illustration of certain exemplary embodiments of the present invention. It is undoubted that those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A fine-grained privacy protection method for bidding documents based on smart contracts, characterized by: The fine-grained privacy protection method for bidding documents based on smart contracts includes the following steps: S1. Release the bidding requirements. The tenderer releases the encrypted bidding requirements through the blockchain platform and sets the bidding deadline; S2. The bidder applies for public and private keys. The bidder generates a public key through the platform for encrypting the bidding documents, and a private key for decrypting and signing the documents; S3. The bidder prepares the bidding content. The bidder prepares the bidding documents and encrypts the contents to ensure secure transmission; S4. The bidder deploys a smart contract. The bidder deploys a smart contract through the blockchain and sets the decryption time of the bidding documents; S5. The tenderer decrypts the bidding documents. After the bidding deadline, the tenderer uses the private key to decrypt the bidding documents and verify their integrity. S6. Ciphertext bidding comparison protocol, which encrypts and compares bid prices through smart contracts to ensure the fairness and privacy of the bidding process.

2. A fine-grained privacy protection method for bidding documents based on smart contracts according to claim 1, characterized in that: In S1, the specific steps are as follows: The tenderer publishes the tender requirements through a decentralized blockchain platform, which must include the bid opening time. All bidding documents must be submitted through designated channels before the deadline; after the bidding documents are successfully submitted, the smart contract automatically generates submission confirmation information and sends it to the bidder to ensure that the bidding documents have been received and cannot be tampered with.

3. A fine-grained privacy protection method for bidding documents based on smart contracts according to claim 1, characterized in that: In S2, the specific steps are as follows: The bidders of the tender requirements issued by the tenderer apply for the Paillier public and private keys from the public key infrastructure PKI ; The Paillier public and private keys applied by each bidder to PKI are consistent; Bidders who are willing to participate in the bidding split the Paillier private key into two parts of the private key and , the split private keys of each bidder are different from each other; Among them, Paillier is a threshold Paillier cryptosystem; the Paillier generation steps are: Key generation: Randomly generate two strong prime numbers p and q of k bits, that is, p=2p'+1, q=2q'+1, where p' and q' are large prime numbers, calculate N=p·q and the greatest common divisor λ of p-1 and q-1, and calculate the inverse element μ of λ modulo N; output the public key pk=(g, N) and the private key sk=(λ, N), where g=N+1; the λ in the private key is split into λ1 and λ2, where λ1 is a random number of 80-112 bits, and λ2=λ·μ-λ1; Encryption: Given a message m, m is required to be a natural number not exceeding N. Encrypt m by calculating [m] = (m + m·N)·rN, where r is a positive integer not less than 112 bits and not exceeding N. Decryption: Given the ciphertext [m] of message m, decryption is done by calculating m=([m]λmodN2-1) / N; Partial decryption: Partial decryption takes a partial private key and encrypted ciphertext as input and calculates [m]λimodN2, where i=1 or 2; Threshold decryption: Threshold decryption takes two partially decrypted ciphertexts as input and obtains the final message m by calculating ([m]λ1modN2·[m]λ2modN2modN2-1) / N; Digital signature generation process: Hash calculation: Perform hash calculation on the message M to obtain the hash value H(M) of the message. , where Hash is a hash function; Signature generation: Use the private key sk to sign the hash value H(M) to obtain the signature S , where Sign is the signature function; Digital signature verification process: Hash calculation: Perform hash calculation on the message M to obtain the hash value H(M) of the message: ； Signature Verification: Use the public key pk to verify the signature S and whether it matches the hash value H(M); If the verification result is True, it means the signature is valid and the message has not been tampered with; If False, the signature is invalid and the message may have been tampered with or the signature does not match.

4. A fine-grained privacy protection method for bidding documents based on smart contracts according to claim 1, characterized in that: In S3, the specific steps are as follows: After the bidder has prepared the bid documents, he uses the public key generated in S2 Encrypted bidding documents : ; Using one of the private keys Partially decrypt the encrypted bidding documents: , except for encrypted quotes Besides; The bidder chooses another partial private key , and use its private key to sign this part of the private key: ; The bidder will encrypt the bid , partially decrypted bidding documents 、Paillier public key And the signature of part of the private key Issued to the tenderer as the tender content of the bid; The bidder sends a signature to the tenderer, and the tenderer needs to submit the same signature to the smart contract during the subsequent bid opening to obtain the corresponding private key.

5. A fine-grained privacy protection method for bidding documents based on smart contracts according to claim 1, characterized in that: In S4, the specific steps are as follows: Any bidder deploys a smart contract on any blockchain that supports smart contracts. The smart contract performs the following operations: back, If a bidder submits the signature of part of the private key in S3 to the smart contract , the smart contract performs the signature verification operation of the bidder: , where r is 0 or 1, 0 means verification failed, 1 means verification passed, If the verification is successful, the smart contract will transfer part of the private key in step 3 Send the tenderer; If the verification fails, it will not be sent.

6. A fine-grained privacy protection method for bidding documents based on smart contracts according to claim 1, characterized in that: In S5, the specific steps are as follows: In the bid opening module, obtain a part of the private key of a bidder The bidder first uses this part of the private key The encrypted bidding documents provided by this bidder Partial decryption , and then use the decryption calculation to obtain the partial decrypted ciphertext And the partial decrypted ciphertext provided by this policyholder Perform the threshold decryption operation to obtain the final decrypted bidding document. The formula is as follows: .

7. A fine-grained privacy protection method for bidding documents based on smart contracts according to claim 1, characterized in that: In S6, the specific steps are as follows: In the bid opening module, the tenderer needs to perform a secure comparison of all bidders' quotations under ciphertext to ensure the fairness of the entire bidding process and not leak the bidders' privacy data; this leads to a secure comparison protocol for ciphertext quotations: Input: Tenderer's encrypted quotation , ; Output: The tenderer obtains , where if ,but On the contrary, if ,but ; Calculation by the tenderer: The bidder tosses a coin to generate a random , when hour, and ; when Time, meter and ,in are two random numbers that satisfy and , ; calculate ; Will Sent to bidders; Bidder calculation: ， ； when ,at this time ; when ,at this time ; Will Send to the tenderer; The tenderer calculates and compares the results : when hour, ; when hour, .

8. A fine-grained privacy protection system for bidding documents based on smart contracts, used to implement the fine-grained privacy protection method for bidding documents based on smart contracts in any one of claims 1 to 7 above, characterized in that: It includes blockchain platform module, key management module, bidding document encryption module, smart contract module, blockchain platform module, file decryption module and bidding comparison module; The blockchain platform module is used to publish encrypted bidding requirements and ensure the transparency and immutability of bidding information; The key management module is used to generate public and private key pairs for bidders and tenderers. The public key is used to encrypt bidding documents, and the private key is used to sign and decrypt documents. The bidding document encryption module is used to encrypt the bidding documents prepared by the bidder to ensure the safe transmission of the bidding documents; Smart contract module, which is used to deploy smart contracts through blockchain, set the decryption time of bidding documents, and automatically execute the bidding process; The file decryption module is used by the tenderer to decrypt the bidding documents using the private key after the bidding deadline, and to verify their integrity and authenticity. The bidding comparison module is used to execute the ciphertext bidding comparison protocol through smart contracts, encrypt and compare the bidders' quotations, and ensure the fairness and privacy of the bidding process.

9. A fine-grained privacy protection system for bidding documents based on smart contracts according to claim 8, characterized in that: in, The key management module and bidding document encryption module include: A public key generation module is used to generate a unique bidder public key, which is used by the bidder to encrypt the content of the bid document to ensure that the bid document remains private and secure during transmission; The private key generation module is used to generate a unique bidder private key, which is held by the bidder and used to digitally sign the bidding document to ensure the authenticity of the document source and to decrypt the encrypted file; The bidding document encryption processing module uses the generated public key to encrypt the bidding document before submission, ensuring that the document will not be obtained or tampered with by unauthorized parties during transmission; The public and private key management module is used to manage the public and private key pairs of bidders and tenderers, ensure the safe storage of the generated public and private key pairs throughout the bidding process, prevent key leakage or tampering, and ensure data security.

10. A fine-grained privacy protection system for bidding documents based on smart contracts according to claim 8, characterized in that: in, The smart contract module and bidding comparison module include: The bidding document decryption time setting module sets the decryption time of the bidding document through the smart contract to ensure that the bidding document can be automatically decrypted at the scheduled time after the bidding deadline so that the tenderer can view the document content; The digital signature verification module verifies the bidding documents by using the public key provided by the tenderer to ensure that the bidding documents have not been tampered with during transmission and to verify the authenticity and integrity of the bidding documents; The encrypted quotation comparison module is used to automatically compare and analyze encrypted bid quotations through smart contracts, ensuring that bidders' quotations remain encrypted during the comparison process, preventing price leakage and ensuring bidding fairness; The bidding process recording module records the entire bidding process through blockchain, including the submission time of the bid, the encrypted comparison results, and the generation of the final bidding results, ensuring the transparency of the bidding process while protecting the bidders' privacy data.

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