A cross-chain data privacy protection method against malicious nodes based on trust relay chain

Abstract

The present invention relates to the field of computer technology, and discloses a cross-chain data privacy protection method against malicious nodes based on a trust relay chain. The present invention runs a trust relay chain in a blockchain system; the node with the highest global trust is taken as a proxy node, and after initialization, the data is encrypted before uploading the private data, and the encrypted data is uploaded to a node on blockchain X; when a node on blockchain Y needs to obtain data on blockchain X, a data acquisition request is sent to the proxy node, and the proxy node requests a re-encryption key from the data owner, and the proxy node uses the re-encryption key to convert the ciphertext CT into a re-encrypted ciphertext, and then runs a decryption algorithm, and if the attributes of the node meet the LSSS access structure, the data is successfully decrypted. Based on attribute proxy re-encryption and a trust relay chain, the present invention realizes efficient, secure, and flexible cross-chain data privacy protection, and improves the relay chain's ability to resist malicious nodes.

Description

Technical Field

[0001] The present invention relates to the field of computer technology, and in particular to a cross-chain data privacy protection method against malicious nodes based on a trust relay chain. Background Art

[0002] With the widespread application of blockchain technology, a large number of blockchain projects based on different application scenarios and design concepts have emerged, forming many isolated value systems. This has led to difficulties in data interaction and business collaboration between blockchains, and cross-chain technology has emerged. However, cross-chain technology faces many challenges in its development, such as the notary mechanism may cause centralized trust problems and single point failure risks, and the hash locking mechanism has risks such as transaction condition leakage, timeout and data transmission failure.

[0003] In cross-chain data interaction, privacy protection is crucial. Existing research mainly focuses on homomorphic encryption, zero-knowledge proof, proxy re-encryption, etc., but there are still various problems. For example, the method based on homomorphic encryption lacks privacy protection in cross-chain transaction amounts; the protocol based on zero-knowledge proof and coin mixing technology faces the risk of man-in-the-middle attacks; the scheme based on conditional proxy re-encryption has centralization risks; the platform using multi-party computing and threshold signature schemes has potential security risks.

[0004] In addition, attacks from malicious nodes also pose a huge threat to cross-chain systems, such as tampering with data, forging transaction information, or denying services, which seriously affects system reliability and availability. Therefore, how to effectively protect data privacy and resist malicious node attacks in a cross-chain environment has become an urgent problem to be solved. Summary of the invention

[0005] In order to solve the defects of the prior art, the present invention provides a cross-chain data privacy protection method against malicious nodes based on a trust relay chain.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0007] The cross-chain data privacy protection method against malicious nodes based on the trust relay chain includes the following steps:

[0008] Step 1: Build a trust relay chain and run the trust relay chain in a cross-chain blockchain system consisting of blockchain X and blockchain Y; select the node with the highest global trust in the trust relay chain as the proxy node, and the remaining nodes as relay nodes, and initialize them; the construction method of the trust relay chain is: any node in the blockchain system The interests are all from one dimensional vector representation, node The interest is recorded as ,… Each blockchain has a chain center and also uses a dimensional vector representation, denoted by ; ,in, is the interest scalar 1, is the interest scalar 2, is the scalar of interest n, Service Scalar 1, Service Scalar 2, scalar n for service; node Interest and Trust in Relay Chains Chain Center The similarity is calculated using the cosine similarity formula as follows ,in is the scalar of interest k, is the service scalar k, n is the vector dimension, and each trust relay chain is composed of links whose distance from the chain center is less than a given threshold If , then the node Allowed to join the trust relay chain b;

[0009] Step 2: After the blockchain system is initialized, the user encrypts the data with the system public key, user private data and an LSSS access structure before uploading the private data. The encrypted data is uploaded to a node on blockchain X in the blockchain system. The node stores the data encryption information on blockchain X for other nodes to query and verify.

[0010] Step 3: When a node on blockchain Y in the blockchain system needs to obtain data on blockchain X, the node on blockchain Y sends a data acquisition request to the proxy node. The proxy node requests the re-encryption key RK from the data owner. The proxy node uses the re-encryption key RK to convert the ciphertext CT into the re-encrypted ciphertext RCT. After the node on blockchain Y obtains the re-encrypted ciphertext RCT, it uses the decryption algorithm to decrypt it. If the node's attributes satisfy the LSSS access structure, the data can be successfully decrypted; otherwise, the decryption fails.

[0011] Further preferably, the global trust degree is calculated as follows: i For node N j The local trust degree is expressed as , i and j are the numbers of different nodes, and the trust relay chain b is connected to node N j The number of nodes that have had service interactions is , then node N j The global trust TV(j) is expressed as:

[0012] ;

[0013] in is the local trust, if node N i and node N j There are N ij times historical interaction record, then node N i For node N j The local trust of is expressed as:

[0014] ;

[0015] in, Indicates the number of successful transactions. It indicates the number of transaction failures. It stipulates that if there is no interaction record between the two parties, the local trust is 0.

[0016] Further preferably, the proxy node regularly broadcasts the latest global trust table to the nodes in the trust relay chain. The global trust table and the inter-chain transaction table are created by the first proxy node of the trust relay chain, wherein the global trust table contains the node name and the corresponding global trust degree; the inter-chain transaction table entry contains the chain name of the source node, the source node, the group name of the destination node, the destination node and the transaction evaluation.

[0017] Further preferably, the initialization method in step 1 is that the proxy node runs the public parameter initialization algorithm and outputs the system public parameters ,in, and is a cyclic group of order 2 prime number p; g, , g and g1 are the generators of G, random numbers , is the domain of integers of p, is a bilinear map, , , is a bit string of arbitrary length, H1 and H2 are collusion-resistant hash functions, Indicates g Power;

[0018] Any blockchain system The relay node obtains the public parameter PP from the trust relay chain, the blockchain system Attribute Authority in Run the key construction algorithm and input the blockchain system The set of all attributes in , choose a random number , generate blockchain system System Master Key , system public key , , where x is a user attribute, is the number of the blockchain system, and N is the number of blockchain systems participating in the cross-chain;

[0019] According to the user attribute set in the system and the system master key , generate user attribute key , where the random number .

[0020] Further preferably, the method of encrypting data using the system public key, user privacy data and an LSSS access structure described in step 2 is:

[0021] Enter the system public key , user privacy data and a LSSS access structure , where M is a matrix, is the number of attributes in the access structure, r is the number of columns in the matrix, is a function that maps attributes to rows of the matrix M by first selecting a random shared secret value , generate a random vector , Represents a random vector The second element in Represents a random vector The rth element in , calculate the secret component ,in , is the t-th row vector of the matrix M, and then selects a random element , calculate the ciphertext , where the first ciphertext module , the second ciphertext module The third ciphertext module , the fourth ciphertext module , is the first ciphertext pair of the fourth ciphertext module, is the fourth ciphertext module A ciphertext pair.

[0022] It is further preferred to dynamically manage the nodes in the trust relay chain, which is divided into two situations: active exit and passive leaving of the nodes in the trust relay chain.

[0023] Further optimization, trust the nodes in the relay chain to actively exit, divided into the following three situations:

[0024] If we trust the node N in the relay chain jTo leave, first of all, N j To the proxy node GH i Send a leave message, then the proxy node GH i To node N j Send a confirmation message to allow it to leave, and broadcast node N to all nodes in the trust relay chain j For messages that have left, all nodes update their neighbors in a timely manner;

[0025] If the current proxy node GH i To leave, first, proxy node GH i Send a leave request message to the relay node and transfer the inter-chain transaction table it maintains to the relay node; then, the relay node selects the node with the second highest global trust from the global trust table as the new proxy node and sends it to the GH. i Send a confirmation message to allow it to leave, and broadcast the new proxy node information to all nodes in the trust relay chain;

[0026] If a relay node were to leave, the trusted relay chain would no longer exist.

[0027] Further preferably, passive leaving means: if the relay node detects that the global trust of a node is lower than a threshold, the node is added to the blacklist of the trust relay chain, and at the same time, all nodes in the trust relay chain are notified, and the node updates its neighbors.

[0028] The present invention also provides an anti-malicious node cross-chain data privacy protection system based on a trust relay chain, comprising:

[0029] Vector setting module: Set an interest vector for each node in the blockchain and a chain center vector for each blockchain to indicate the core business direction of the blockchain;

[0030] Trust relay chain building module: Use the cosine similarity formula to calculate the similarity between each node and the central vector of the blockchain chain; when the similarity of the node is higher than the preset threshold, the node is allowed to join the trust relay chain associated with the blockchain;

[0031] Proxy node election module: After the trust relay chain is built, the global trust of each node is calculated by collecting historical interaction records between nodes. The node with the highest global trust is elected as the proxy node, responsible for data re-encryption and trust management of cross-chain transactions.

[0032] Data owner encryption data module: used to encrypt data;

[0033] Data upload module: used for data upload;

[0034] Data request and re-encryption module: used for data request and re-encryption;

[0035] Data decryption and access control module: used for data decryption and access control;

[0036] Transaction record and trust update module: used to record transaction information and update the global trust table;

[0037] Active exit and passive leaving module: used to handle the active exit and passive leaving of nodes in the trust relay chain.

[0038] The beneficial effects of the present invention are as follows: the present invention can effectively solve the problems faced by the prior art, such as incomplete privacy protection, low efficiency of encryption mechanism, and centralized proxy re-encryption service, and at the same time cope with the challenges brought by malicious node attacks. The present invention is based on attribute proxy re-encryption and trust relay chain, aiming to achieve efficient, secure, and flexible cross-chain data privacy protection and improve the relay chain's ability to resist malicious nodes. The present invention not only improves the security and privacy of cross-chain transactions, but also effectively resists attacks from malicious nodes by introducing trust relay chain and global trust management mechanism. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0040] Figure 1 It is a diagram of the interaction relationship between the trust relay chains of the cross-chain system;

[0041] Figure 2 This is a schematic diagram of the cross-chain data privacy protection model;

[0042] Figure 3 This is a graph showing the changes in the system interaction success rate after malicious nodes join. DETAILED DESCRIPTION

[0043] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0044] like Figure 1-Figure 3 As shown, the present invention provides a method for cross-chain data privacy protection against malicious nodes based on a trust relay chain, comprising the following steps:

[0045] Step 1: Build a trust relay chain and run the trust relay chain in a cross-chain blockchain system consisting of blockchain X and blockchain Y; the node with the highest global trust in the trust relay chain will serve as the proxy node, and the remaining nodes will be relay nodes and initialized.

[0046] In blockchain X and blockchain Y, each node is set with an interest vector to indicate its interest in a specific field (such as supply chain management, intellectual property protection). At the same time, a chain center vector is set for each blockchain to indicate the core business direction of the blockchain.

[0047] The cosine similarity formula is used to calculate the similarity between each node and the chain center vector of blockchain X (or blockchain Y). When the similarity of a node is higher than the preset threshold, the node is allowed to join the trust relay chain associated with blockchain X (or blockchain Y).

[0048] After the trust relay chain is built, the global trust of each node is calculated by collecting historical interaction records between nodes. The node with the highest global trust is elected as the proxy node, responsible for data re-encryption and trust management of cross-chain transactions.

[0049] The method for constructing the trust relay chain is:

[0050] Any node in the blockchain system The interests are all from one dimensional vector representation, node The interest is recorded as ,… Each blockchain has a chain center and also uses a dimensional vector representation, denoted by ; ,in, is the interest scalar 1, is the interest scalar 2, is the scalar of interest n, Service Scalar 1, Service Scalar 2, scalar n for service; node Interest and Trust in Relay Chain Chain Center The similarity is calculated using the cosine similarity formula as follows ,in is the scalar of interest k, is the service scalar k, n is the vector dimension, and each trust relay chain is composed of links whose distance from the chain center is less than a given threshold If , then the node Allowed to join the trust relay chain b.

[0051] The calculation method of the global trust is as follows: i For node N j The local trust degree is expressed as , i and j are the numbers of different nodes, and the trust relay chain b is connected to node Nj The number of nodes that have had service interactions is , then node N j The global trust TV(j) is expressed as:

[0052] ;

[0053] in is the local trust, if node N i and node N j There are N ij times historical interaction record, then node N i For node N j The local trust of is expressed as:

[0054] ;

[0055] in, Indicates the number of successful transactions. It indicates the number of transaction failures. It stipulates that if there is no interaction record between the two parties, the local trust is 0.

[0056] The proxy node regularly broadcasts the latest global trust table to the nodes in the trust relay chain. The global trust table and inter-chain transaction table are created by the first proxy node of the trust relay chain. The global trust table contains the node name and the corresponding global trust degree; the inter-chain transaction table entry contains the chain name of the source node, the source node, the group name of the destination node, the destination node and the transaction evaluation.

[0057] The initialization method is that the proxy node runs the public parameter initialization algorithm and outputs the system public parameters ,in, and is a cyclic group of order 2 prime number p; g, , g and g1 are the generators of G, random numbers , is the domain of integers of p, is a bilinear map, , , is a bit string of arbitrary length, H1 and H2 are collusion-resistant hash functions, Indicates g In the present invention, unless otherwise specified, the superscript indicates an exponential form;

[0058] Any blockchain system The relay node obtains the public parameter PP from the trust relay chain, the blockchain system Attribute Authority in Run the key construction algorithm and input the blockchain system The set of all attributes in , choose a random number , generate blockchain system System Master Key , system public key , , where x is a user attribute, is the number of the blockchain system, and N is the number of blockchain systems participating in the cross-chain;

[0059] According to the user attribute set in the system and the system master key , generate user attribute key , where the random number .

[0060] Step 2: After the blockchain system is initialized, the user encrypts the data with the system public key, user private data and an LSSS access structure before uploading the private data. The encrypted data is uploaded to a node on blockchain X in the blockchain system. The node stores the data encryption information on blockchain X for other nodes to query and verify.

[0061] The method of encrypting data using a system public key, user privacy data and an LSSS access structure is:

[0062] Enter the system public key , user privacy data and a LSSS access structure , where M is a matrix, is the number of attributes in the access structure, r is the number of columns in the matrix, is a function that maps attributes to rows of the matrix M by first selecting a random shared secret value , generate a random vector , Represents a random vector The second element in Represents a random vector The rth element in , calculate the secret component ,in , is the t-th row vector of the matrix M, and then selects a random element , calculate the ciphertext , where the first ciphertext module , the second ciphertext module The third ciphertext module , the fourth ciphertext module , is the first ciphertext pair of the fourth ciphertext module, is the fourth ciphertext module A ciphertext pair.

[0063] Step 3: When the node on blockchain Y in the blockchain system needs to obtain data on blockchain X, the node on blockchain Y sends a data acquisition request to the proxy node. The proxy node requests the re-encryption key RK from the data owner. The proxy node uses the re-encryption key RK to convert the ciphertext CT into the re-encrypted ciphertext RCT. After the node on blockchain Y obtains RCT, it uses the decryption algorithm to decrypt it. If the node's attributes satisfy the LSSS access structure, the data can be successfully decrypted; otherwise, the decryption fails.

[0064] After the user initiates a data acquisition request, the proxy node requests the re-encryption key RK from the data owner. The proxy node uses the re-encryption key RK to convert the ciphertext CT into the re-encrypted ciphertext RCT. The proxy node records this transaction in the trust relay chain and updates the global trust table. The user obtains RCT to run the decryption algorithm, inputs the re-encrypted ciphertext RCT, and the user's attribute key , the specific steps of the algorithm are as follows:

[0065] for ,and ,like{ } is the effective share of the secret value s according to the matrix M, and the user attribute set Satisfy access structure ,Right now , then there exists a constant set , is the tth constant, so that Established, then, calculate to obtain the pre-variable , and then calculate the formula to obtain the important secret value , and then obtain the user's private data , then the proxy node updates the global trust after the node transaction is completed and checks whether the node trust is below the global trust threshold. After each cross-chain transaction, the proxy node records the transaction information and updates the global trust table. If the node exhibits good behavior in the transaction (such as correctly decrypting and legally using the data), its global trust may increase; otherwise, it may decrease.

[0066] Dynamic management of nodes within the trust relay chain is divided into two situations: active exit and passive exit of nodes within the trust relay chain.

[0067] The nodes in the trust relay chain actively exit in the following three situations:

[0068] If we trust the node N in the relay chainj To leave, first of all, N j To the proxy node GH i Send a leave message, then the proxy node GH i To node N j Send a confirmation message to allow it to leave, and broadcast node N to all nodes in the trust relay chain j For messages that have left, all nodes update their neighbors in a timely manner;

[0069] If the current proxy node GH i To leave, first, the agent node GH i Send a leave request message to the relay node and transfer the inter-chain transaction table it maintains to the relay node; then, the relay node selects the node with the second highest global trust from the global trust table as the new proxy node and sends it to the GH. i Send a confirmation message to allow it to leave, and broadcast the new proxy node information to all nodes in the trust relay chain;

[0070] If a relay node were to leave, the trusted relay chain would no longer exist.

[0071] Passive leaving means: if the relay node detects that the global trust of a node is lower than the threshold, the node will be added to the blacklist of the trust relay chain, and all nodes in the trust relay chain will be notified at the same time, and the node will update its neighbors.

[0072] The trust relay chain will handle the active and passive exit of nodes in the chain (such as being blacklisted because the trust level is below the threshold) accordingly. This includes updating the global trust table, broadcasting node departure messages, etc. to ensure the stability and security of the system.

[0073] Figure 1 The architecture and interaction relationship of the trust relay chain in the cross-chain system are shown. The trust relay chain is located in the center and connects each blockchain system participating in the cross-chain. In each blockchain system, there are multiple nodes, and the nodes are connected through a certain trust relationship. The interest vector of the node and the chain center vector are similarity calculated by the cosine similarity formula to determine whether the node can join the trust relay chain. The nodes in the trust relay chain are divided into proxy nodes and relay nodes. The proxy node is responsible for maintaining the global trust table and the inter-chain transaction table, and regularly broadcasts the latest information to other nodes. The lines between nodes represent the transaction interaction relationship, and the historical records of transaction interactions are used to calculate the local trust between nodes, and then calculate the global trust.

[0074] Figure 2The overall process and key components of cross-chain data privacy protection are depicted. The entire model shows the entire process of data upload, storage, access control and data decryption based on the source chain, destination chain, trust relay chain, attribute center and interstellar file system, highlighting the collaborative relationship between the components and how to use blockchain technology to ensure the privacy and security of data in a cross-chain environment, and prevent data leakage and unauthorized access.

[0075] Figure 3 Indicates the change in the system interaction success rate after the addition of malicious nodes: In the initial stage, when the system is in normal operation, the interaction success rate remains at a high level (for example, around 95%), indicating that when there is no interference from malicious nodes, transactions and data interactions between nodes can proceed smoothly. When the proportion of malicious nodes reaches 0.5, the interaction success rate only decreases by 2%, indicating that this solution has a high ability to resist malicious nodes.

[0076] Assume that there are two independent blockchain systems, Blockchain X and Blockchain Y. Blockchain X focuses on supply chain management, involving data records of the entire process from production to sales of goods; while Blockchain Y focuses on intellectual property protection, recording the ownership and transaction information of various innovative achievements. Now, a multinational company needs to cross-chain interact its supply chain data on Blockchain X with the intellectual property data on Blockchain Y to achieve more efficient business collaboration and data analysis.

[0077] The present invention also provides an anti-malicious node cross-chain data privacy protection system based on a trust relay chain, comprising:

[0078] Vector setting module: In blockchain X and blockchain Y, each node is set with an interest vector to indicate its interest in a specific field (such as supply chain management, intellectual property protection); at the same time, a chain center vector is set for each blockchain to indicate the core business direction of the blockchain;

[0079] Trust relay chain building module: Use the cosine similarity formula to calculate the similarity between each node and the center vector of blockchain X or blockchain Y; when the similarity of a node is higher than a preset threshold, the node is allowed to join the trust relay chain associated with blockchain X or blockchain Y;

[0080] Proxy node election module: After the trust relay chain is built, the global trust of each node is calculated by collecting historical interaction records between nodes. The node with the highest global trust is elected as the proxy node, responsible for data re-encryption and trust management of cross-chain transactions.

[0081] Data owner encryption data module: On blockchain X, data owners (such as a supply chain company) need to upload their supply chain data to cloud storage. Before uploading, the data owner encrypts the data using the system public key, user privacy data and an LSSS access structure to ensure that only nodes that meet the access structure can decrypt the data;

[0082] Data upload module: The encrypted data is uploaded to a node on blockchain X, which stores the data encryption information on the blockchain for other nodes to query and verify;

[0083] Data request and re-encryption module: When a node on blockchain Y (such as an intellectual property agency) needs to obtain data on blockchain X, it sends a data acquisition request to the proxy node. The proxy node requests the re-encryption key RK from the data owner and uses RK to convert the ciphertext CT into the re-encrypted ciphertext RCT;

[0084] Data decryption and access control module: After the node on blockchain Y obtains RCT, it uses its attribute key to run the decryption algorithm. If the node's attributes satisfy the LSSS access structure, the data can be successfully decrypted. Otherwise, the decryption fails;

[0085] Transaction record and trust update module: After each cross-chain transaction, the proxy node will record the transaction information and update the global trust table. If the node exhibits good behavior in the transaction (such as correctly decrypting and legally using data), its global trust may increase; otherwise, it may decrease.

[0086] Active exit and passive departure module: For active exit and passive departure of nodes in the chain (such as being blacklisted due to trust being below the threshold), the trust relay chain will handle it accordingly. This includes updating the global trust table, broadcasting node departure messages, etc., to ensure the stability and security of the system.

[0087] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A cross-chain data privacy protection method against malicious nodes based on a trust relay chain, characterized in that: The following steps are involved: Step 1: Build a trust relay chain and run the trust relay chain in a cross-chain blockchain system consisting of blockchain X and blockchain Y; select the node with the highest global trust in the trust relay chain as the proxy node, and the remaining nodes as relay nodes, and initialize them; the construction method of the trust relay chain is: any node in the blockchain system The interests are all from one dimensional vector representation, node The interest is recorded as ,… Each blockchain has a chain center and also uses a dimensional vector representation, denoted by ; ,in, is the interest scalar 1, is the interest scalar 2, is the scalar of interest n, Service Scalar 1, Service Scalar 2, scalar n for service; node The interest and trust in the relay chain b is the center of the chain The similarity is calculated using the cosine similarity formula as follows ,in is the scalar of interest k, is the service scalar k, n is the vector dimension, and each trust relay chain is composed of links whose distance from the chain center is less than a given threshold If , then the node Allowed to join the trust relay chain b; Step 2: After the blockchain system is initialized, the user encrypts the data with the system public key, user private data and an LSSS access structure before uploading the private data. The encrypted data is uploaded to a node on blockchain X in the blockchain system. The node stores the data encryption information on blockchain X for other nodes to query and verify. Step 3: When the node on blockchain Y in the blockchain system needs to obtain data on blockchain X, the node on blockchain Y sends a data acquisition request to the proxy node. The proxy node requests the re-encryption key RK from the data owner. The proxy node uses the re-encryption key RK to convert the ciphertext CT into the re-encrypted ciphertext RCT. After the node on blockchain Y obtains the re-encrypted ciphertext RCT, it uses the decryption algorithm to decrypt it. If the node's attributes satisfy the LSSS access structure, the data is successfully decrypted; otherwise, the decryption fails.

2. According to claim 1, a method for protecting cross-chain data privacy against malicious nodes based on a trust relay chain, characterized in that: The calculation method of the global trust is as follows: i For node N j The local trust degree is expressed as , i and j are the numbers of different nodes, and the trust relay chain b is connected to node N j The number of nodes that have had service interactions is , then node N j The global trust TV(j) is expressed as: ； in is the local trust, if node N i and node N j There are N ij times historical interaction record, then node N i For node N j The local trust of is expressed as: ； in, Indicates the number of successful transactions. It indicates the number of transaction failures. It stipulates that if there is no interaction record between the two parties, the local trust is 0.

3. According to claim 1, a method for protecting cross-chain data privacy against malicious nodes based on a trust relay chain, characterized in that: The proxy node regularly broadcasts the latest global trust table to the nodes in the trust relay chain. The global trust table and inter-chain transaction table are created by the first proxy node of the trust relay chain. The global trust table contains the node name and the corresponding global trust degree; the inter-chain transaction table entry contains the chain name of the source node, the source node, the group name of the destination node, the destination node and the transaction evaluation.

4. According to claim 1, a method for protecting cross-chain data privacy against malicious nodes based on a trust relay chain, characterized in that: The initialization method described in step 1 is that the proxy node runs the public parameter initialization algorithm and outputs the system public parameters ,in, and is a cyclic group of order 2 prime number p; g, , g and g1 are the generators of G, random numbers , is the domain of integers of p, is a bilinear map, , , is a bit string of arbitrary length, H1 and H2 are collusion-resistant hash functions, Indicates g Power; Any blockchain system The relay node obtains the public parameter PP from the trust relay chain, the blockchain system Attribute Authority in Run the key construction algorithm and input the blockchain system The set of all attributes in , choose a random number , generate blockchain system System Master Key , system public key , , where x is a user attribute, is the number of the blockchain system, and N is the number of blockchain systems participating in the cross-chain; According to the user attribute set in the system and the system master key , generate user attribute key , where the random number .

5. According to claim 4, a method for protecting cross-chain data privacy against malicious nodes based on a trust relay chain is characterized in that: The method described in step 2 to encrypt data using the system public key, user private data and an LSSS access structure is: Enter the system public key , user privacy data and a LSSS access structure , where M is a matrix, is the number of attributes in the access structure, r is the number of columns in the matrix, is a function that maps attributes to rows of the matrix M by first selecting a random shared secret value , generate a random vector , Represents a random vector The second element in Represents a random vector The rth element in , calculate the secret component ,in , is the t-th row vector of the matrix M, and then selects a random element , calculate the ciphertext , where the first ciphertext module , the second ciphertext module The third ciphertext module , the fourth ciphertext module , is the first ciphertext pair of the fourth ciphertext module, is the fourth ciphertext module A ciphertext pair.

6. According to claim 1, a method for protecting cross-chain data privacy against malicious nodes based on a trust relay chain, characterized in that: Dynamic management of nodes within the trust relay chain is divided into two situations: active exit and passive exit of nodes within the trust relay chain.

7. According to claim 6, a method for protecting cross-chain data privacy against malicious nodes based on a trust relay chain, characterized in that: The nodes in the trust relay chain actively exit in the following three situations: If we trust the node N in the relay chain j To leave, first of all, N j To the proxy node GH i Send a leave message, then the proxy node GH i To node N j Send a confirmation message to allow it to leave, and broadcast node N to all nodes in the trust relay chain j For messages that have left, all nodes update their neighbors in a timely manner; If the current proxy node GH i To leave, first, the agent node GH i Send a leave request message to the relay node and transfer the inter-chain transaction table it maintains to the relay node; then, the relay node selects the node with the second highest global trust from the global trust table as the new proxy node and sends it to the GH. i Send a confirmation message to allow it to leave, and broadcast the new proxy node information to all nodes in the trust relay chain; If a relay node were to leave, the trusted relay chain would no longer exist.

8. According to claim 6, a method for protecting cross-chain data privacy against malicious nodes based on a trust relay chain, characterized in that: Passive leaving means: if the relay node detects that the global trust of a node is lower than the threshold, the node will be added to the blacklist of the trust relay chain, and all nodes in the trust relay chain will be notified at the same time, and the node will update its neighbors.

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