Oblique photography three-dimensional model transaction evidence storage scheme based on block chain and zero watermark

Abstract

The invention discloses an oblique photography three-dimensional model transaction evidence storage scheme based on a block chain and a zero watermark, and the scheme comprises the steps: firstly constructing the zero watermark through the skewness of model data, and storing the zero watermark and encrypted transaction data in an interstellar file system; secondly, a transaction evidence storage system is designed based on an intelligent contract, lightweight information such as a data storage address is deployed in a block chain based on the system, and dependence on a trusted third party is eliminated. And then, the two transaction parties call the smart contract through the system to carry out transaction, so that the traceability and non-tampering of the transaction record are ensured. Finally, the two transaction parties can verify the copyright information, integrity and authenticity of the data through the transaction voucher information, thereby effectively maintaining the legitimate rights and interests of the two transaction parties. Experimental results show that copyright protection of the data is achieved through the zero-watermarking algorithm, transparency and credibility of the transaction process are achieved through the transaction evidence storage scheme, and legal rights and interests of the two transaction parties can be guaranteed.

Description

Technical Field

[0001] The present invention belongs to the field of geographic information security and data transaction, and relates to a transaction and notarization scheme for oblique photography three-dimensional models based on blockchain and zero watermark. Background Art

[0002] In recent years, with the continuous development of geographic information technology, oblique photography 3D models, as a special 3D model, provide accurate basic data support for digital twins in virtual space. This type of data has the characteristics of high value, sensitive information and easy duplication. Therefore, in the process of data circulation, it is necessary to ensure that the entire transaction process is traceable to protect the rights and interests of all parties and promote the safe circulation of data. Traditional data transactions use digital watermarking technology to covertly add copyright information to the data, and store the copyright information as transaction evidence in a third party. However, this type of transaction method depends on the credibility of both parties and third parties. When there are rebels in the transaction parties or third parties, the legitimate rights and interests of both parties cannot be guaranteed. Therefore, how to build a safe and reliable transaction mechanism to avoid malicious framing by data copyright holders and illegal abuse and reselling of data by middlemen and data buyers, and ensure the fairness and credibility of transactions, is an urgent problem to be solved in the current oblique photography 3D model data transaction process.

[0003] Blockchain technology has the characteristics of decentralization, traceability, tamper-proof and transparency, which effectively makes up for the defects of traditional transaction methods. Therefore, by combining blockchain technology, the problem of untrustworthiness in the data transaction process can be effectively solved. As the core component of blockchain, smart contract technology has the characteristics of programmability, automatic execution and trusted operation, which further enhances the application ability of blockchain in trusted transactions. Therefore, in order to enable data to be traded safely and reliably, the method of combining blockchain and digital watermarking has become an advantageous choice. At present, there are trusted transaction methods combining blockchain and digital watermarking, such as Xu et al. combining Hyperledger Fabric with interstellar file storage to design a zero watermark registration scheme, which ensures the safe and reliable registration of watermarks and related parameter information, while realizing lossless copyright protection of remote sensing images. Wang et al. realized the keyword search function of images stored in the system based on Ethereum smart contracts, solved the data expansion problem of blockchain through the interstellar file storage system, and realized the copyright traceability of images. These methods mainly protect the rights and interests of copyright holders, ignore the legitimate rights and interests of data buyers, and lead to insufficient fairness and credibility of transactions.

[0004] In view of the lack of a secure and reliable transaction solution for oblique photography 3D models, this paper proposes a transaction and notarization solution for oblique photography 3D models based on blockchain and zero watermark based on the technical features of blockchain and digital watermark. This solution utilizes the tamper-proof characteristics of blockchain and the ability of zero watermark technology to protect data copyright, and realizes secure and reliable transaction notarization of oblique photography 3D model data. Summary of the invention

[0005] The main technical problem solved by the present invention is how to provide a method that not only solves the problem that traditional data transaction methods rely on the credibility of both parties to the transaction and a third party, but also fairly protects the legitimate rights and interests of both parties to the transaction, which can save costs and improve security and credibility. It is a three-dimensional model transaction notarization solution based on blockchain and zero watermark with broad application prospects.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: to provide an oblique photography three-dimensional model transaction notarization solution based on blockchain and zero watermark, including: a zero watermark generation step, a zero watermark detection step and an oblique photography three-dimensional model transaction notarization system based on blockchain and zero watermark.

[0007] Zero watermark generation steps include:

[0008] Read the original copyright image W, apply Logistic mapping to encrypt the copyright image, and obtain the encrypted copyright image W′;

[0009] Read the vertices of the original oblique photography 3D model and find the 1-neighborhood point coordinates of each vertex;

[0010] Perform SVD on each vertex corresponding to the 1-domain point to obtain the right singular value vector V and the last component of the right singular value vector

[0011] according to Calculate the dot product and angle with the unit normal vector in the Z-axis direction; set the angle threshold, and take the vertices with angles greater than the threshold as feature points;

[0012] Calculate the Euclidean distance between the vertex and the feature point, and group all vertices according to the principle of minimum distance;

[0013] Calculate the center point coordinates of all vertices in each group, and calculate the distance r between the vertex and the center point coordinates; sort r, and use the following formula to calculate the skewness corresponding to the group according to the Z value of the coordinates of the 2 / 3 points with the largest distance; where n represents the number of vertices in each group, z i represents the Z coordinate corresponding to the i-th point, μ represents the mean value of the data set, σ represents the standard deviation of the data set, and S represents the value of skewness;

[0014] Using the dot product dp of the above vectors, a stable index between the watermark information and the copyright information is established according to the following formula, where index is the index value, dp represents the dot product of the two vectors, l is the length of the one-dimensional watermark information, and u is the magnification factor; index = [dp × 10 u ]mod l

[0015] The voting principle is used to determine the watermark information. The voting principle requires setting a list equal to the size of the copyright information, denoted as M = {m′ i =0, i=1,2,…,l};

[0016] If the skewness corresponding to the group is greater than zero, the watermark information at the corresponding index is 1, otherwise it is 0;

[0017] After all groups have generated watermark information, they are binarized using the following formula:

[0018] Convert the generated one-dimensional watermark information M′ into a two-dimensional sequence to obtain the final watermark information M″;

[0019] The zero watermark M* is generated by performing an XOR operation on M″ and the encrypted copyright information W′ through the following formula, where XNOR is the XNOR operator symbol; M*=XNOR(W′,M″)

[0020] The generated zero watermark is used to store transaction information in the InterPlanetary File System.

[0021] Zero watermark detection steps include:

[0022] Read the oblique photography three-dimensional model data of the watermark information to be detected;

[0023] The same watermark information is generated by using the aforementioned zero watermark generation method for the oblique photography three-dimensional model data;

[0024] XOR the watermark information with the zero watermark stored in the Interstellar File System to obtain the copyright image to be detected;

[0025] Decrypting the copyright image to be detected to obtain the detected copyright image;

[0026] Calculate the similarity between the copyright image to be detected and the original copyright image.

[0027] The oblique photography 3D model transaction and notarization system based on blockchain and zero watermark includes:

[0028] Data information notarization module, data transaction execution module, smart contract and interstellar file storage system;

[0029] Data information storage module: It is mainly for the copyright holders of the data to realize the reliable storage of data information; through smart contracts 1, it ensures that the relevant information and data summary of the copyright holder can be permanently and tamper-proof stored in the blockchain;

[0030] Data transaction execution module: mainly for data buyers, to verify and execute data transaction conditions; through smart contracts 2, to ensure the transparency and immutability of transaction records, and automatically obtain information such as the storage address of data in the Interstellar File System;

[0031] Smart contract: The copyright holder and the buyer interact through smart contracts, and the information of both parties and transaction records are stored in the blockchain through smart contracts;

[0032] Interstellar File System: Given a hash value, the corresponding file can be found for download. When the copyright holder uploads the data to the Interstellar File Storage System, the Interstellar File System will return the unique hash address corresponding to the data. The buyer can query and download the data through the Interstellar File System.

[0033] The execution process of the oblique photography 3D model transaction and notarization system based on blockchain and zero watermark includes:

[0034] When the data buyer obtains the data of interest, the data buyer submits a transaction application to the data copyright holder. When the identity verification is successful, the data copyright holder obtains the public key of the data buyer;

[0035] The copyright holder encrypts the data with the purchaser's public key and uploads it to the Interstellar File System along with the zero-watermark image to obtain the corresponding hash value for storage;

[0036] At the same time, the copyright holder divides the data into blocks and calculates the Merkle tree root of the data; and processes the data with Hash256 as the unique ID of the data;

[0037] The copyright holder uploads the data and zero-watermark storage hash address value, transaction conditions, data Merkle tree root, data ID and other information to the blockchain through smart contract 1 in the data information storage module of the system, and obtains the corresponding contract address;

[0038] The copyright holder sends the contract address to the buyer. The buyer enters the contract address, transaction conditions and buyer information through the data transaction execution module in the system. The system verifies and executes the transaction by calling smart contract 2. After verification, the system returns the hash value of the data storage to the buyer.

[0039] The buyer downloads the encrypted data from the Interstellar File System based on the hash value and decrypts the data using the private key;

[0040] Smart Contract 2 stores the entire transaction process in the blockchain.

[0041] The security and fairness of the oblique photography 3D model transaction and storage system based on blockchain and zero watermark include:

[0042] Deposit: Both parties involved in the transaction need to pay a corresponding deposit to encourage both parties to abide by the transaction rules and complete the entire transaction process as required. Once one party violates the regulations, its deposit will be deducted;

[0043] Function execution constraints: Through the requirements and modifier keywords of the Solidity language in the smart contract, each function in the smart contract is constrained to ensure that the function can only be accessed and called by designated users;

[0044] Data storage: The copyright holder encrypts the data using the buyer's public key, uploads it to the Interstellar File System, and submits the returned hash address to the buyer through a smart contract;

[0045] Data transaction: During the transaction, the copyright holder sends the data and the storage address of the zero watermark in the Interstellar File System, the Merkle tree root of the data, and the ID of the data to the buyer;

[0046] When storing data, the data is encrypted with the purchaser's public key, so that no one except the purchaser and the copyright holder can obtain the data.

[0047] When the data buyer finds that the data does not meet the requirements, the corresponding data ID is generated for the data and compared with the data ID stored in the smart contract; if the data information matches, the data obtained by the buyer is authentic; if it does not match, it indicates that the copyright owner has violated the rules;

[0048] When the copyright holder encounters transaction data leakage or theft, the zero watermark can be used to effectively verify the copyright owner of the data; and when the purchaser makes malicious accusations against the copyright holder or the copyright holder provides false data to the purchaser, both parties to the transaction can compare the data ID and the Merkle tree root of the data stored in the transaction information with the value of the suspicious data, thereby safeguarding the rights and interests of both parties.

[0049] The present invention discloses a solution for storing oblique photography 3D model transactions based on blockchain and zero watermark. The solution utilizes the tamper-proof characteristics of blockchain and the ability of zero watermark technology to protect data copyright, thereby realizing efficient and reliable storage of oblique photography 3D model data transactions. Experiments show that the solution can provide a new solution for reliable storage of oblique photography 3D model data transactions, and provide strong technical support for the safe circulation, reliable transactions and wide application of data. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only schematic diagrams of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0051] Figure 1 A flowchart of a transaction and notarization scheme for oblique photography three-dimensional models based on blockchain and zero watermark provided for an implementation example of the present invention;

[0052] Figure 2 (a)- Figure 2 (d) 4 oblique photography 3D model example data provided for the implementation example of the present invention;

[0053] Figure 3 (a)- Figure 3 (d) zero-watermark images constructed from four oblique photography three-dimensional models provided in the embodiment of the present invention;

[0054] Figure 4 A flowchart of the rights protection of both parties to a transaction provided for an implementation example of the present invention; DETAILED DESCRIPTION

[0055] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0056] The following is a detailed description of a transaction and storage scheme of a three-dimensional model of oblique photography based on blockchain and zero watermark in conjunction with the accompanying drawings and implementation examples. Figure 1 A flow chart of the evidence storage solution implemented by the present invention;

[0057] Zero watermark generation example:

[0058] Read the original copyright image W, apply Logistic mapping to encrypt the copyright image, and obtain the encrypted copyright image W′;

[0059] Read the vertices of the original oblique photography 3D model, find the 1-neighborhood point coordinates of each vertex, and attach Figure 2 (a)-(d) are four oblique photography 3D model example data provided by the embodiment of the present invention;

[0060] Perform SVD on each vertex corresponding to the 1-domain point to obtain the right singular value vector;

[0061] According to equations (1) and (2), the last component of the right singular value vector Calculate the dot product dp and the angle θ with the unit normal vector of the Z axis; set the angle threshold, and take the vertices with θ greater than the threshold as feature points. Represents the unit normal vector corresponding to the Z axis;

[0062] According to formula (3), the Euclidean distance between the vertex and the feature point is calculated, and all vertices are grouped according to the minimum distance principle. In the formula, d represents the Euclidean distance; Fe j =(x j ,y j , z j ) represents the coordinates of the feature points; P i =(x i ,y,z i ) represents the coordinates of the vertex.

[0063] Calculate the center point coordinates of all vertices in each group, and then calculate the distance r between the vertex and the center point coordinates; sort r, select the Z value corresponding to the coordinates of the 2 / 3 points with the largest distance, and calculate the skewness corresponding to the group according to formula (4). In the formula, n represents the number of vertices in each group, z i represents the Z coordinate corresponding to the i-th point, μ represents the mean value of the data set, σ represents the standard deviation of the data set, and S represents the value of skewness;

[0064] Using the dp value of the corresponding feature point in each group, a stable index between the watermark information and the copyright information is established according to formula (5), where index is the index value, l is the length of the one-dimensional watermark information, and u is the magnification factor; index = [dp × 10 u ]mod l (5)

[0065] Since the number of selected feature points is much larger than the length of the watermark, the index values ​​corresponding to different feature points may be the same. Therefore, the voting principle is needed to determine the watermark information. The voting principle requires setting a list equal to the size of the copyright information, denoted as M = {m′ i =0, i=1,2,…,l}; the voting principle is as shown in formula (6). If the skewness corresponding to the group is greater than zero, the watermark information at the corresponding index is 1, otherwise it is 0;

[0066] After all groups have generated watermark information, they are binarized using formula (7);

[0067] Convert the generated one-dimensional watermark information M′ into a two-dimensional sequence to obtain the final watermark information M″;

[0068] Through formula (8), M″ is XORed with the encrypted copyright information W′ to generate the zero watermark M * , where XNOR is the exclusive OR operator, Figure 3 (a)-(d) are zero-watermark images constructed using the oblique photography three-dimensional model provided by the embodiment of the present invention; M * =XNOR(W′,M″) (8)

[0069] The generated zero watermark is stored in the InterPlanetary File System to maintain copyright protection during the circulation of data;

[0070] Zero watermark detection example:

[0071] Read the oblique photography three-dimensional model data of the watermark information to be detected;

[0072] The same watermark information is generated by using the aforementioned zero watermark generation method for the oblique photography three-dimensional model data;

[0073] XOR the watermark information with the zero watermark stored in the blockchain to obtain the copyrighted image to be detected;

[0074] Perform Logistic mapping decryption on the copyright image to be detected to obtain the detected copyright image;

[0075] The similarity between the detected copyright image and the original copyright image is calculated to determine the copyright owner of the data.

[0076] An example of the execution process of the oblique photography 3D model transaction and notarization system based on blockchain and zero watermark is as follows:

[0077] When the data buyer obtains the data of interest, the data buyer submits a transaction application to the data copyright owner. During this process, the copyright owner needs to authenticate the buyer to ensure that the buyer's identity is authentic and valid. After the identity authentication is successful, the copyright owner will obtain the buyer's public key for use in the subsequent data encryption process;

[0078] The copyright holder encrypts the data with the purchaser's public key, ensuring that only the purchaser can decrypt it, and uploads it together with the zero-watermark image to the Interstellar File System to obtain the corresponding hash value for storage;

[0079] At the same time, after the copyright holder divides the data into blocks, it calculates the Merkle tree root of the data to detect the approximate location where the data has been tampered with and ensure the integrity of the data; and processes the data with Hash256 as the unique ID of the data to ensure that each piece of data can be distinguished from other data;

[0080] The copyright holder uploads the data and zero-watermark storage hash address value, transaction conditions, data Merkle tree root, data ID and other information to the blockchain through smart contract 1 in the data information storage module of the system, and the copyright holder will obtain a unique contract address;

[0081] The copyright holder sends the contract address to the buyer, and the buyer conducts the transaction through the data transaction execution module in the system;

[0082] The buyer enters the contract address, transaction conditions and buyer information in the system. The system verifies and executes the transaction by calling smart contract 2. After the verification is passed, the buyer obtains the hash value of the data storage;

[0083] The purchaser downloads the encrypted data from the Interstellar File System based on the hash value;

[0084] The purchaser uses the private key to decrypt the data and use it;

[0085] Smart Contract 2 stores the entire transaction process in the blockchain.

[0086] The security and fairness guarantee mechanism of the oblique photography 3D model transaction and storage system based on blockchain and zero watermark is as follows:

[0087] Deposit: In order to ensure the smooth progress of the transaction and motivate both parties to abide by the rules, the system has established a deposit mechanism. Both parties involved in the transaction need to pay a corresponding deposit to encourage both parties to abide by the transaction rules and complete the entire transaction process as required. Once one party fails to complete the transaction as required or violates the agreement, the system will deduct the corresponding deposit according to the provisions of the smart contract, so as to punish the defaulting party and ensure the fairness of the transaction;

[0088] Function execution constraints: By using the Solidity language's requirement statements and modifier keywords in smart contracts, each function can be constrained to ensure that only specific users are allowed to access and call the function, thereby improving the security of the contract and the standardization of operations;

[0089] Data storage: the copyright holder encrypts the data with the buyer’s public key, uploads it with a zero watermark to the Interstellar File System, and submits the generated hash address to the buyer through a smart contract;

[0090] Data transaction: During the transaction, the copyright holder sends the data and the storage address of the zero watermark in the Interstellar File System, the Merkle tree root of the data, and the ID of the data to the buyer, providing the buyer with the key information needed to ensure the integrity of the data and verify its authenticity, ensuring that the buyer can accurately verify the source of the data and that it has not been tampered with;

[0091] If the data buyer finds that the data does not meet the requirements, he can generate the corresponding data ID and the Merkle tree root of the data and compare them with the data ID and Merkle tree root stored in the smart contract; if the two are consistent, it means that the data received by the buyer is authentic; if they are inconsistent, it means that the copyright owner has violated the rules;

[0092] When the copyright holder encounters transaction data leakage or theft, the zero watermark technology can be used to effectively verify the copyright owner of the data; and when the buyer makes malicious accusations against the copyright holder or the copyright holder provides false data to the buyer, both parties to the transaction can use the data ID and the Merkle tree root of the data stored in the transaction information to compare with the corresponding value of the suspicious data. This comparison process will ensure the authenticity and integrity of the data, further protect the legitimate rights and interests of both parties to the transaction, and prevent any party from being unfairly harmed; Appendix Figure 4 A flowchart of rights protection for both parties of a transaction provided for an implementation example of the present invention;

[0093] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A transaction and storage scheme for oblique photography 3D models based on blockchain and zero watermark, characterized in that: include: Zero watermark generation step, zero watermark detection step and oblique photography three-dimensional model transaction and notarization system based on blockchain and zero watermark, wherein: The steps of generating watermark information include: Perform Logistic encryption on the copyright image to obtain the encrypted copyright matrix W′; Read the vertices of the original oblique photography 3D model and find the 1-neighborhood point coordinates of each vertex; Perform SVD on the 1-neighborhood point coordinates of each vertex to obtain the right singular value vector V and the last component of the right singular value vector according to Calculate the dot product and angle with the unit normal vector in the Z-axis direction; set the angle threshold, and take the vertices with angles greater than the threshold as feature points; Calculate the Euclidean distance between the vertex and the feature point, and group all vertices according to the principle of minimum distance; Calculate the center point coordinates of all vertices in each group, and then calculate the distance r between the vertex and the center point coordinates; sort r, select the Z value corresponding to the coordinates of the 2 / 3 points with the largest distance, and use the following formula to calculate the skewness corresponding to each group, where n represents the number of vertices in each group, and z i represents the Z coordinate corresponding to the i-th point, μ represents the mean value of the data set, σ represents the standard deviation of the data set, and S represents the value of skewness; Using the dp value of the corresponding feature point in each group, a stable index between the watermark information and the copyright information is established according to the following formula, where index is the index value, dp represents the dot product of two vectors, l is the length of the one-dimensional watermark information, and u is the magnification factor; index=[dp×10 u ]mod l Set a list with the same size as the copyright information, denoted as M = {m i ′=0,i=1,2,…,l}, the voting principle is used to determine the watermark information; If the skewness corresponding to the group is greater than zero, the watermark information at the corresponding index is 1, otherwise it is 0; After all groups have generated watermark information, they are binarized using the following formula: The generated one-dimensional watermark information M′ is converted into a two-dimensional sequence to obtain the final watermark information M″; M″ is XORed with the encrypted copyright information W′ by the following formula to generate the zero watermark M * , where XNOR is the exclusive OR operator; M*=XNOR(W′,M″) Store the generated zero watermark into the InterPlanetary File System; The watermark information detection steps include: Read the oblique photography three-dimensional model data of the watermark information to be detected; Generate watermark information using the method of the watermark information generation step; The generated watermark information is compared with the zero watermark M stored in the Interstellar File System. * Perform XOR operation; The result of XOR operation is decrypted by Logistic mapping to obtain the copyright image to be detected; Calculate the similarity between the copyright image to be detected and the original copyright image; The oblique photography 3D model transaction and notarization system based on blockchain and zero watermark includes: Data information storage module: It is mainly for the copyright holders of data to realize the reliable storage of data information; through smart contracts 1, it ensures that the relevant information and data summary of the copyright holder can be permanently and tamper-proof stored in the blockchain; Data transaction execution module: mainly for data buyers, to verify and execute data transaction conditions; through smart contracts 2, to ensure the transparency and immutability of transaction records, and automatically obtain information such as the storage address of the data in the Interstellar File System; Smart contract: The copyright holder and the buyer interact through smart contracts, and the information of both parties and transaction records are stored in the blockchain through smart contracts; Interstellar File System: Given a hash value, the corresponding file can be found and downloaded. When the copyright holder uploads the data to the Interstellar File Storage System, the Interstellar File System will return the unique hash address corresponding to the data. The buyer can query and download the data through the Interstellar File System.

2. The oblique photography 3D model transaction and evidence storage solution based on blockchain and zero watermark according to claim 1 is characterized in that: The execution process of the oblique photography three-dimensional model transaction and evidence storage system based on blockchain and zero watermark includes: When the data buyer obtains the data of interest, the data buyer submits a transaction application to the data copyright holder. When the identity verification is successful, the data copyright holder obtains the public key of the data buyer; The copyright holder encrypts the data with the purchaser's public key and uploads it to the Interstellar File System along with the zero-watermark image to obtain the corresponding hash value for storage; At the same time, the copyright holder divides the data into blocks and calculates the Merkle tree root of the data; and processes the data with Hash256 to obtain the unique ID of the data; The copyright holder uploads the data and zero-watermark storage hash address value, transaction conditions, data Merkle tree root, data ID and other information to the blockchain through smart contract 1 in the data information storage module of the system, and obtains the corresponding contract address; The copyright holder sends the contract address to the buyer. The buyer enters the contract 1 address, transaction conditions and buyer information through the data transaction execution module in the system to conduct the transaction. The system verifies and executes the transaction by calling smart contract 2. After the verification is passed, the system returns the hash value of the data storage to the buyer. The buyer downloads the encrypted data from the Interstellar File System based on the hash value and decrypts the data using the private key; Smart Contract 2 stores the entire transaction process in the blockchain.

3. The oblique photography 3D model transaction and evidence storage solution based on blockchain and zero watermark according to claim 1 is characterized in that: The blockchain-based and zero-watermark-based oblique photography three-dimensional model transaction and evidence storage system contains security and fairness guarantee mechanisms, including: Deposit: Both parties involved in the transaction need to pay a corresponding deposit to encourage both parties to abide by the transaction rules and complete the entire transaction process as required. Once one party violates the regulations, its deposit will be deducted; Function execution constraints: By using the Solidity language's requirement statements and modifier keywords in smart contracts, each function can be constrained to ensure that only specific users are allowed to access and call the function, thereby improving the security of the contract and the standardization of operations; Data storage: the copyright holder encrypts the data with the buyer’s public key, uploads it with a zero watermark to the Interstellar File System, and submits the generated hash address to the buyer through a smart contract; Data transaction: During the transaction, the copyright holder sends the data and the storage address of the zero watermark in the Interstellar File System, the Merkle tree root of the data, and the ID of the data to the buyer.

4. The oblique photography 3D model transaction and evidence storage solution based on blockchain and zero watermark according to claim 3 is characterized in that: The transaction data is encrypted using the purchaser's public key and then stored, so that no one except the purchaser and the copyright holder can obtain the traded data.

5. The oblique photography 3D model transaction and evidence storage solution based on blockchain and zero watermark according to claim 3 is characterized in that: The transaction parties can verify the data and protect their rights through transaction information, including: When the data buyer finds that the data does not meet the requirements, they can generate the corresponding data ID and the Merkle tree root of the data and compare them with the data ID and Merkle tree root stored in the smart contract; If the two are consistent, it means that the data received by the purchaser is authentic and reliable; if they are inconsistent, it means that the copyright holder has violated the law; When the copyright holder encounters transaction data leakage or theft, the zero watermark can be used to effectively verify the copyright owner of the data; and when the buyer makes malicious accusations against the copyright holder or the copyright holder provides false data to the buyer, both parties to the transaction can use the data ID and the Merkle tree root of the data stored in the transaction information to compare with the corresponding value of the suspicious data, thereby protecting the legitimate rights and interests of both parties.

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