A verifiable privacy-preserving cross-chain system based on relay chains

Abstract

The present invention provides a verifiable privacy-protected cross-chain system based on a relay chain, which belongs to the field of blockchain. The system includes: a source chain, a target chain, a financial chain and a relay chain; the sender initiates a cross-chain transaction request through the source chain and forwards it to the relay chain; the relay chain forwards the cross-chain transaction request to the receiver in the target chain; the receiver performs a cross-chain transaction based on the cross-chain transaction request, and forwards the transaction result to the relay chain through the target chain; the relay chain generates a cross-chain transaction record, and re-encrypts it to obtain a credit ciphertext for storage; the financial institution generates a credit inquiry request after receiving the financing application of the financing enterprise, and forwards it to the relay chain through the financial chain; the relay chain determines the credit ciphertext of the corresponding financing enterprise according to the credit inquiry request, and forwards it to the financial institution; the financial institution jointly with the corresponding financing enterprise decrypts the credit ciphertext to obtain the plaintext credit information of the corresponding financing enterprise. The present invention improves the security and efficiency of cross-chain transactions and cross-chain financing.

Description

Technical Field

[0001] The present invention relates to the field of blockchain, and in particular to a verifiable privacy-preserving cross-chain system based on a relay chain. Background Art

[0002] In the field of supply chain finance, different enterprises use heterogeneous blockchain platforms to exchange business data, involving upstream chains, logistics chains, downstream chains, and financial chains. The single-chain architecture can no longer meet the large amount of information exchange needs in supply chain finance, and the interconnection between heterogeneous blockchains is an urgent problem to be solved. At the same time, there are a large number of financing scenarios in supply chain finance, and the risk information assessment of financing enterprises by financial institutions is the basis of financing, which also requires a large amount of information exchange to complete. However, due to the heterogeneity of information on different chains and the decentralization of cross-chain information exchange, the trusted verification of cross-chain information has become a challenge. It is urgent to use cross-chain technology and verifiable privacy protection technology to achieve reliable and secure transmission of cross-chain information. In the financing scenario, it is necessary to collect and evaluate the credit information of enterprises by collecting information from multiple chains. This process is important but inefficient. Since the information structures stored in different heterogeneous chains are different, how to quickly and uniformly query the credit information of enterprises from other multiple chains through the relay chain is a problem; at the same time, since business transaction information belongs to sensitive information of enterprises, how to protect the privacy of cross-chain transaction information is also a problem. In the existing cross-chain solutions, the standardized processing of information in multi-source heterogeneous cross-chain scenarios is not considered. In the cross-chain solutions using the relay chain as the core, the transaction information on the relay chain is not fully utilized, resulting in low multi-chain query efficiency and complicated operations. At the same time, the large amount of cross-chain business information retained on the relay chain has not achieved targeted privacy protection, and cannot well guarantee the security, verifiability and reliability of the information. Summary of the invention

[0003] The purpose of this invention is to provide a verifiable privacy-preserving cross-chain system based on a relay chain, which can improve the security and efficiency of cross-chain transactions and cross-chain financing.

[0004] To achieve the above object, the present invention provides the following solutions:

[0005] A verifiable privacy-preserving cross-chain system based on a relay chain, comprising: a source chain, a target chain, a financial chain and a relay chain; the source chain, the target chain and the financial chain are all connected to the relay chain; the nodes in the source chain are senders, the nodes in the target chain are receivers, and the nodes in the financial chain are financial institutions;

[0006] The sender is used to initiate a cross-chain transaction request through the source chain; the source chain is used to forward the cross-chain transaction request to the relay chain;

[0007] The relay chain is used to forward the cross-chain transaction request to the corresponding receiver in the target chain; the receiver is used to perform a cross-chain transaction based on the cross-chain transaction request, and forward the transaction result to the relay chain through the target chain;

[0008] The relay chain is also used to generate a cross-chain transaction record according to the cross-chain transaction request and the transaction result, re-encrypt the cross-chain transaction record, obtain the corresponding credit ciphertext and save it;

[0009] The financial institution is used to generate a credit inquiry request after receiving a financing application from a financing enterprise, and forward the credit inquiry request to the relay chain through the financial chain; the financing enterprise is a node in the source chain or a node in the target chain;

[0010] The relay chain is also used to determine the credit ciphertext corresponding to the financing enterprise according to the credit inquiry request, and forward the credit ciphertext to the corresponding financial institution in the financial chain;

[0011] The financial institution is also used to jointly decrypt the credit information ciphertext with the corresponding financing enterprise to obtain the plaintext credit information of the corresponding financing enterprise for financing.

[0012] Optionally, the relay chain is also used to verify the validity of the cross-chain transaction request, and forward the cross-chain transaction request to the corresponding recipient in the target chain after the verification.

[0013] Optionally, the relay chain is also used to forward the transaction result to the corresponding sender in the source chain.

[0014] Optionally, the relay chain uses a threshold homomorphic encryption algorithm to re-encrypt the cross-chain transaction records.

[0015] Optionally, the financial institution is also used to verify the credit data source of the credit ciphertext.

[0016] Optionally, the financial institution is also used to establish a point-to-point encrypted transmission channel with the financing enterprise to decrypt the credit investigation ciphertext.

[0017] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects: a relay chain is used as an intermediate bridge to realize cross-chain transactions and cross-chain financing between heterogeneous chains, thereby improving the security of cross-chain transactions and cross-chain financing, and re-encrypting cross-chain transaction records on the relay chain, thereby improving the efficiency of cross-chain transactions and cross-chain financing. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] 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 will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0019] Figure 1 The overall architecture diagram of the relay chain-based verifiable privacy-preserving cross-chain system provided by the present invention;

[0020] Figure 2 The overall flow chart of cross-chain transactions and cross-chain financing for the present invention;

[0021] Figure 3 A module diagram of the relay chain-based verifiable privacy-preserving cross-chain system provided by the present invention.

[0022] Explanation of symbols: 1-sender, 2-source chain, 3-relay chain, 4-target chain, 5-receiver, 6-financing enterprise, 7-financial chain, 8-financial institution. DETAILED DESCRIPTION

[0023] 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.

[0024] The purpose of this invention is to provide a verifiable privacy-preserving cross-chain system based on a relay chain. A verifiable privacy-preserving cross-chain protocol is proposed for supply chain finance scenarios, and detailed designs are made for relay storage, credit inquiry, privacy protection and other processes to improve the security and transmission efficiency of cross-chain information exchange, so as to promote the application of blockchain in supply chain scenarios.

[0025] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] like Figure 1 As shown, the verifiable privacy protection cross-chain system based on relay chain provided by the present invention includes: source chain 2, target chain 4, financial chain 7 and relay chain 3. The source chain 2, the target chain 4 and the financial chain 7 are all connected to the relay chain 3. The source chain 2, the target chain 4, the financial chain 7 and the relay chain 3 are all blockchains.

[0027] The node in the source chain 2 is the sender 1, the node in the target chain 4 is the receiver 5, and the node in the financial chain 7 is the financial institution 8. The financing enterprise 6 is a node in the source chain 2 or a node in the target chain 4.

[0028] Among them, sender 1 is the data sending user, who is the owner of the transaction information of source chain 2. The user is registered on relay chain 3 and can initiate cross-chain requests.

[0029] Receiver 5 is a data receiving user, who is the recipient of transaction information on target chain 4.

[0030] Source Chain 2 is the blockchain where the node that initiates the cross-chain transaction is located, and stores the business information and transaction information generated by each enterprise in the supply chain finance.

[0031] Target chain 4 is the blockchain where the receiving node of the cross-chain transaction is located, and is responsible for receiving cross-chain information.

[0032] Relay Chain 3 is the core of the entire cross-chain system, and is mainly responsible for application chain management, cross-chain transaction management, trusted verification of cross-chain transactions, and encrypted storage of cross-chain transactions.

[0033] The financial institution 8 is responsible for initiating a credit inquiry request to the relay chain 3 during the financing stage, obtaining the historical transaction records of the enterprise 6 requesting financing, and conducting a credit assessment.

[0034] The financial chain 7 is an alliance chain composed of financial institutions 8, which is responsible for recording financial business data, such as loan contracts, corporate credit results and other information.

[0035] The financing enterprise 6 is the financing initiator and is responsible for selectively providing some credit data to the financial institution 8 through P2P data connection or offline operation.

[0036] The following is a detailed introduction to the overall process of cross-chain transactions and cross-chain financing.

[0037] The sender 1 is used to initiate a cross-chain transaction request through the source chain 2. The source chain 2 is used to forward the cross-chain transaction request to the relay chain 3.

[0038] The relay chain 3 is used to forward the cross-chain transaction request to the corresponding receiver 5 in the target chain 4. The receiver 5 is used to perform a cross-chain transaction based on the cross-chain transaction request, and forward the transaction result to the relay chain 3 through the target chain 4.

[0039] Furthermore, the relay chain 3 is also used to verify the validity of the cross-chain transaction request, and forward the cross-chain transaction request to the corresponding receiver 5 in the target chain 4 after the verification is passed.

[0040] The relay chain 3 is also used to generate a cross-chain transaction record according to the cross-chain transaction request and the transaction result, re-encrypt the cross-chain transaction record, obtain the corresponding credit ciphertext and save it. The relay chain 3 is also used to forward the transaction result to the corresponding sender 1 in the source chain 2. Specifically, the relay chain 3 uses a threshold homomorphic encryption algorithm to re-encrypt the cross-chain transaction record.

[0041] The threshold homomorphic encryption algorithm requires at least two keys to decrypt, ensuring that a single party cannot obtain the plaintext. The present invention uses the Paillier threshold homomorphic encryption algorithm for encryption.

[0042] The financial institution 8 is used to generate a credit inquiry request after receiving the financing application from the financing enterprise 6, and forward the credit inquiry request to the relay chain 3 through the financial chain 7.

[0043] The relay chain 3 is also used to determine the credit ciphertext corresponding to the financing enterprise 6 according to the credit inquiry request, and forward the credit ciphertext to the corresponding financial institution 8 in the financial chain 7.

[0044] The financial institution 8 is also used to jointly decrypt the credit information ciphertext with the corresponding financing enterprise 6 to obtain the plaintext credit information of the corresponding financing enterprise 6 for financing.

[0045] Furthermore, the financial institution 8 is also used to verify the credit data source of the credit ciphertext, and after the verification is passed, jointly with the corresponding financing enterprise 6 to decrypt the credit ciphertext.

[0046] Specifically, the financial institution 8 is also used to establish a point-to-point encrypted transmission channel with the financing enterprise 6 to decrypt the credit investigation ciphertext.

[0047] The present invention completes the cross-chain data interoperability in the supply chain finance scenario through the transaction stage and the financing stage. The overall flow chart is as follows: Figure 2 The following will explain in detail the operation process of the transaction stage and the financing stage.

[0048] (1) Transaction phase: The node on source chain 2 initiates a cross-chain transaction request and generates metadata for this business transaction, including transaction ID, sender address, receiver address and other information. Source chain 2 verifies the identity through the smart contract module and encrypts the data. If the verification is successful, it initiates a cross-chain information exchange request and forwards the request to relay chain 3. Relay chain 3 listens to the cross-chain exchange request and verifies the signature of the sending node. After confirming that the cross-chain transaction is legal, it generates a corresponding record on relay chain 3. Relay chain 3 forwards the cross-chain transaction to target chain 4. The node on target chain 4 verifies the cross-chain transaction. After confirming that it is correct, it returns the confirmation transaction result to relay chain 3. After receiving the transaction result, relay chain 3 uses the Paillier homomorphic encryption threshold algorithm to re-encrypt the business data in the cross-chain transaction and save it on relay chain 3.

[0049] The present invention performs data re-encryption on the relay chain 3 to ensure the privacy of the transaction information stored on the relay chain 3, and also lays the foundation for the second stage of credit inquiry, assisting in verifiable credit inquiry.

[0050] (2) Financing stage: After receiving the financing application from the financing enterprise 6, the financial institution 8 constructs a transaction query containing the address of the financing enterprise and other information, and initiates a credit inquiry request to the relay chain 3. The relay chain 3 searches for the relevant cross-chain transaction records based on the address of the financing enterprise, returns the homomorphically encrypted credit information, and saves the query operation record of the financial institution 8 on the chain. After receiving the credit ciphertext, the financial institution 8 verifies the authenticity of the information. Since the financial institution 8 has only one key and can only obtain partially decrypted ciphertext, the financial institution 8 needs to obtain another part of the key from the corresponding financing enterprise 6 to decrypt the credit plaintext. The financial institution 8 uses an offline communication method to initiate a point-to-point encrypted connection to the enterprise user, requesting the financing enterprise 6 to partially decrypt the ciphertext. The financing enterprise 6 selects the partially decrypted ciphertext according to the protocol and returns it to the financial institution 8. The financial institution 8 combines the partial decryption results provided by the financing enterprise 6 to obtain the plaintext credit information, complete the risk assessment, and decide whether to approve the financing application of the financing enterprise 6 based on the assessment results.

[0051] In order to better understand the solution of the present invention, the following is a further explanation from different modules. The present invention proposes a verifiable privacy protection cross-chain protocol (VPPC protocol) and completes the system design based on this protocol, such as Figure 3 As shown, it mainly includes cross-chain transaction processing module, smart contract module, privacy protection module, message forwarding module, cross-chain data re-encryption module, cross-chain credit inquiry module, security verification module and offline communication module.

[0052] (1) The cross-chain transaction processing module is the core module of the first phase, responsible for handling the entire process control of cross-chain transactions, including: providing a cross-chain transaction submission interface, checking the transaction format and parameter legitimacy, and receiving valid cross-chain transactions. The cross-chain transaction processing module is connected to the smart contract module to verify and execute the smart contract logic in the cross-chain transaction.

[0053] Specifically, the cross-chain transaction processing module is used to parse cross-chain transaction details, verify signatures, obtain key information such as the target chain, and use the cross-chain queue monitoring function to obtain the cross-chain transaction request initiated in the source chain from the source chain transaction queue, and parse the cross-chain transaction information. The cross-chain transaction request will carry the unique identifier of the target chain, such as the target chain ID; query the mapping table according to the target chain ID to obtain the target chain information. The system will maintain a mapping table of the cross-chain network topology, recording the IDs and key information of different chains, such as network addresses, consensus mechanisms, interface protocols, etc.

[0054] After parsing, the on-chain verification rules are called to fully verify the validity of the cross-chain transaction, including:

[0055] Transaction format verification: Verify whether the cross-chain transaction format and structure are correct and comply with the transaction encoding specifications of the source chain.

[0056] Signature verification: Call the signature verification algorithm of the chain to verify whether the transaction signature is valid.

[0057] Smart contract verification: Verify whether the relevant information of cross-chain transactions is correct through smart contracts, such as transaction syntax, parameters, etc.

[0058] Duplicate transaction verification: Check whether this transaction hash has been confirmed on the chain to avoid duplicate execution.

[0059] If the above verification passes, it means the transaction is valid and can be transmitted to the target chain. If the above verification fails, it means the cross-chain transaction verification is invalid, the transaction is discarded, and the processing result is returned to the sender, and the invalid transaction is recorded in the log.

[0060] Drive cross-chain transactions to be executed on the target chain, while continuously monitoring cross-chain transaction feedback results, waiting for the target chain to confirm the transaction, and obtaining the target chain execution results. Among them, the nodes on the target chain will confirm the transaction according to the consensus algorithm and generate a transaction receipt. The cross-chain transaction processing module obtains the transaction receipt information of the target chain through the client, parses the receipt, and extracts the transaction execution results. If the transaction is successful, the cross-chain data re-encryption module will be triggered, and the successful transaction result will be returned to the source chain; if the transaction fails, the source chain transaction will be rolled back, and the transaction result will be recorded as a failure in the relay chain.

[0061] The cross-chain transaction processing module follows the cross-chain business data exchange protocol: the nodes in the source chain construct cross-chain transactions containing encrypted business data and send them to the relay chain. The relay chain verifies the validity of the transaction and forwards it to the nodes in the target chain. The nodes in the target chain confirm receipt and notify the relay chain. After receiving the confirmation, the relay chain re-encrypts the business data using the homomorphic encryption algorithm and records it in the ledger.

[0062] (2) The smart contract module is responsible for the compilation, verification and execution of smart contracts. The smart contract module connects to the cross-chain transaction processing module to receive trigger requests and return execution results.

[0063] The smart contract module is used to develop, deploy and execute cross-chain smart contracts suitable for supply chain scenarios. It has the following functions: standardized supply chain contract templates to quickly implement typical supply chain business processes; contracts support cross-chain calls, and one contract can trigger a contract on another chain; support for uploading logistics information to the chain to form traceable supply chain data; realize automatic triggering of payments based on contracts and automation of supply chain capital flows; the access control module is responsible for identity authentication and authority control.

[0064] (3) The privacy protection module is used to encrypt and control access to sensitive user data and transaction information. The privacy protection module is connected to the cross-chain transaction processing module and the smart contract module to protect the privacy data involved in the transaction from being leaked. The main functions include: using symmetric encryption algorithms to encrypt or hash key transaction data to avoid plain text storage and transmission of important information; using encrypted communication protocols in cross-chain transactions to prevent sensitive information from being obtained by intermediate nodes during cross-chain transmission; and providing a policy configuration interface to allow users to customize the level of transaction privacy protection.

[0065] In this embodiment, corresponding smart contract modules and privacy protection modules are deployed in the source chain, target chain, financial chain and relay chain.

[0066] (4) The message forwarding module is responsible for transmitting messages and events between different chains. The message forwarding module is connected to the cross-chain transaction processing module to obtain messages related to cross-chain transactions and state changes and forward them to the target chain. The message forwarding module plays the role of message transfer in the system and is responsible for reliably transmitting cross-chain transaction information from the source chain to the target chain. In the present invention, the relay chain is the implementation subject of the message forwarding module.

[0067] The message forwarding module first receives cross-chain interaction requests or transactions from the source chain; parses the transaction to obtain information such as the target chain identifier and request purpose, selects the target chain required to execute the request based on the parsed information, establishes a connection with the target chain based on the communication protocol, and forwards the cross-chain transaction to the target chain. Once the target chain processes the forwarded message and generates a response, the message forwarding module is responsible for receiving and parsing the response data of the target chain.

[0068] (5) The cross-chain data re-encryption module is connected to the message forwarding module and is used to re-encrypt and store the data on the relay chain after the message is successfully transmitted across the chain. The cross-chain data re-encryption module is deployed in the relay chain.

[0069] The cross-chain data re-encryption module is called in the later stage of the cross-chain transaction phase, and the transaction records on the relay chain are re-encrypted through the Paillier homomorphic encryption threshold algorithm. After receiving the response from the target chain, the transaction records are processed accordingly according to the response result.

[0070] Specifically, the initiator initiates a cross-chain transaction request on the source chain, selects a recipient, generates transaction information, encrypts the transaction information using the recipient's public key, obtains preliminary encrypted information, and sends the preliminary encrypted information to the relay chain. After the relay chain node verifies the validity of the preliminary encrypted information, it adds a verification signature to the preliminary encrypted information and re-encrypts the preliminary encrypted information using a threshold homomorphic encryption algorithm. The ciphertext after threshold homomorphic encryption is recorded in the relay chain ledger. The relay chain node distributes partial keys to the sender and the nodes on the financial chain. The present invention sets the threshold value to 2, that is, two keys are needed to decrypt the ciphertext to obtain the plaintext after decryption.

[0071] The process of re-encrypting the initial encrypted information using the threshold encryption algorithm is as follows: the relay chain node generates a random number r as a partial key. The encryption public key T and multiple decryption private keys are calculated according to the threshold encryption algorithm formula using the initiator's public key, the receiver's public key and the random number r. At least two private keys are required to decrypt the ciphertext. The relay node parses the credit information from the transaction information according to the cross-chain protocol, and uses the public key T and the threshold encryption algorithm to encrypt the credit information to obtain the ciphertext after threshold homomorphic encryption.

[0072] (6) The cross-chain credit inquiry module realizes cross-chain inquiry of users’ credit records on various chains and is the core module of the second phase. The cross-chain credit inquiry module is connected with the cross-chain transaction processing module and the security verification module to obtain and verify the user’s cross-chain credit information during credit inquiry. The cross-chain credit inquiry module is deployed in the relay chain.

[0073] The cross-chain credit inquiry module mainly provides the following functions: construct a credit inquiry transaction based on the credit inquiry request initiated by the financial institution, call the relay chain query interface, and pass in the address of the financial institution; record the inquiry transaction and timestamp in the relay chain; the relay chain consensus node queries the credit ciphertext stored on the relay chain based on the source chain ID and sending node address of the credit inquiry request; propagate cross-chain records to the relay chain nodes through the cross-chain information asynchronous consensus mechanism, and the consensus node returns the credit ciphertext to the financial institution.

[0074] Usually, credit inquiries will directly require enterprises to provide credit information such as relevant transaction records. In this case, there is a possibility that enterprises provide false information, thereby increasing the risk of financing. At the same time, it is noted that this does not fully utilize the information on the relay chain. Therefore, credit inquiries will verify the information provided by enterprises based on the transaction records stored on the relay chain. At the same time, it can also ensure that the query actions of financial institutions are recorded by the relay chain, ensuring traceability.

[0075] The cross-chain credit inquiry module follows the corporate financing information inquiry protocol: the financing enterprise initiates a financing application to the financial institution. The financial institution constructs an inquiry transaction and requests the relay chain to return the credit information of the financing enterprise. The relay chain returns the credit ciphertext to the financial institution based on the historical transaction records of the financing enterprise. The financial institution establishes a point-to-point encrypted channel with the financing enterprise. The financing enterprise chooses to partially decrypt and return it to the financial institution. The financial institution uses the partial decryption results to verify the authenticity and integrity of the information. The financial institution decides whether to approve the application based on the enterprise risk assessment results.

[0076] (7) The security verification module is responsible for the security verification of transactions and on-chain operations, including signature verification, permission control, etc. The security verification module is connected with the cross-chain transaction processing module and the cross-chain credit inquiry module to perform security verification on the operation requests of each module to ensure that the obtained corporate credit data is authentic and reliable. The security verification module is deployed in each node of the financial chain.

[0077] The workflow is as follows: obtain the credit ciphertext from the cross-chain credit inquiry module, and perform identity check and verification on the credit data source based on the returned data signature. Specifically, the digital certificate verification method is adopted. The credit data source carries a digital certificate to verify whether the certificate chain comes from an authoritative CA and whether the certificate content matches the data source identity. The match indicates that the data source is reliable. After that, the credit ciphertext is hashed and matched with the returned content hash to ensure that it has not been tampered with during the data transmission process; if the data has been tampered with, the data information is discarded and the information verification failure is fed back. After the financing enterprise provides a partial decryption result, the homomorphic encryption property is used to verify the matching of the decryption result and the ciphertext, and the credit data is decrypted. The received credit data plaintext is format checked to ensure that it conforms to the predetermined structure, and the binding relationship between the data and the specific enterprise is confirmed through the enterprise identifier, and stored in the local database for use.

[0078] (8) The offline communication module is connected to the cross-chain credit inquiry module to assist the cross-chain credit inquiry module in completing the acquisition of complete credit information. Its workflow is as follows: monitor the offline communication request initiated by the financial institution, obtain the target user of the execution request, establish a point-to-point secure encrypted transmission channel, and transmit the decryption request for the ciphertext segment; after the target user receives the communication request, it sends the data to the financial institution through the transmission channel again, and completes the offline communication between the two ends after confirmation by both parties. The offline communication module is deployed in each node in the financial chain.

[0079] The present invention realizes cross-chain interoperability between different blockchains for supply chain finance business scenarios, adopts the relay chain as an intermediate bridge to realize cross-chain transactions and financing between heterogeneous chains, re-encrypts transaction information on the relay chain, unifies the data format and encrypts and stores information, and assists in the completion of the first-stage cross-chain transaction; uses the Paillier threshold homomorphic encryption algorithm to realize the verifiability of credit information, adopts two-stage information acquisition to ensure information security, and greatly improves the efficiency of the financing stage.

[0080] In summary, the present invention has the following technical effects:

[0081] (1) Low security risk: Cross-chain access control can effectively reduce the security risk of cross-chain operations. At the same time, the relay chain uses the Paillier homomorphic encryption algorithm to encrypt and store transaction records during cross-chain operations, ensuring the security of data on the relay chain and reducing the risk of data leakage. When retrieving historical transaction records from the relay chain, the transaction participants need to provide another part of the ciphertext in order to obtain the transaction records, ensuring that the transaction records will not be abused while achieving data verifiability.

[0082] (2) High financing efficiency: Cross-chain transactions are completed through two-stage transactions, making full use of the information stored on the relay chain to assist credit inquiries, without the need to broadcast credit information requests to all chains, which improves the efficiency of information inquiries. At the same time, financial institutions can only partially decrypt credit information, which also ensures the verifiability of credit information. After obtaining the credit information on the relay chain, another part of the financing enterprise's information is obtained through point-to-point transmission, which ensures the overall efficiency of financing.

[0083] (3) Verifiability: The secondary storage of information on the relay chain uses the Paillier homomorphic encryption algorithm, with the threshold set to 2. Two private key holders are required to decrypt the plaintext. At the same time, it can verify whether the information provided by both parties is true and accurate, avoiding the possibility of companies maliciously providing false credit information.

[0084] (4) Good versatility: It realizes cross-chain transactions and financing between heterogeneous blockchains. Since the information storage formats between heterogeneous blockchains are different, in cross-chain transaction scenarios, the relay chain will unify the format before re-encrypting the data for storage so that different blockchains can use the information after retrieving it.

[0085] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0086] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A verifiable privacy-preserving cross-chain system based on a relay chain, characterized in that: The relay chain-based verifiable privacy protection cross-chain system includes: a source chain, a target chain, a financial chain and a relay chain; the source chain, the target chain and the financial chain are all connected to the relay chain; the nodes in the source chain are senders, the nodes in the target chain are receivers, and the nodes in the financial chain are financial institutions; The sender is used to initiate a cross-chain transaction request through the source chain; the source chain is used to forward the cross-chain transaction request to the relay chain; The relay chain is used to forward the cross-chain transaction request to the corresponding receiver in the target chain; the receiver is used to perform a cross-chain transaction based on the cross-chain transaction request, and forward the transaction result to the relay chain through the target chain; The relay chain is also used to generate a cross-chain transaction record according to the cross-chain transaction request and the transaction result, re-encrypt the cross-chain transaction record, obtain the corresponding credit ciphertext and save it; specifically, the initiator initiates a cross-chain transaction request on the source chain, selects a recipient, generates transaction information, encrypts the transaction information using the recipient's public key, obtains preliminary encrypted information, and sends the preliminary encrypted information to the relay chain; after the relay chain node verifies the validity of the preliminary encrypted information, it adds a verification signature to the preliminary encrypted information, and re-encrypts the preliminary encrypted information using a threshold homomorphic encryption algorithm, and records the ciphertext after threshold homomorphic encryption in the relay chain ledger; the relay chain node distributes part of the key to the sender and the nodes on the financial chain; The financial institution is used to generate a credit inquiry request after receiving a financing application from a financing enterprise, and forward the credit inquiry request to the relay chain through the financial chain; the financing enterprise is a node in the source chain or a node in the target chain; The relay chain is also used to determine the credit ciphertext corresponding to the financing enterprise according to the credit inquiry request, and forward the credit ciphertext to the corresponding financial institution in the financial chain; The financial institution is also used to jointly decrypt the credit information ciphertext with the corresponding financing enterprise to obtain the plaintext credit information of the corresponding financing enterprise for financing.

2. The relay chain-based verifiable privacy protection cross-chain system according to claim 1, characterized in that: The relay chain is also used to verify the validity of the cross-chain transaction request, and after the verification is passed, forward the cross-chain transaction request to the corresponding recipient in the target chain.

3. The relay chain-based verifiable privacy protection cross-chain system according to claim 1, characterized in that: The relay chain is also used to forward the transaction result to the corresponding sender in the source chain.

4. The relay chain-based verifiable privacy protection cross-chain system according to claim 1, characterized in that: The relay chain uses a threshold homomorphic encryption algorithm to re-encrypt the cross-chain transaction records.

5. The relay chain-based verifiable privacy protection cross-chain system according to claim 1, characterized in that: The financial institution is also used to verify the credit data source of the credit ciphertext.

6. The relay chain-based verifiable privacy protection cross-chain system according to claim 1, characterized in that: The financial institution is also used to establish a point-to-point encrypted transmission channel with the financing enterprise to decrypt the credit investigation ciphertext.

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