A cross-chain data sharing method

Abstract

The technical solution of this invention provides a cross-chain data sharing method. A select group of high-trust nodes from various blockchains act as notaries for cross-chain data sharing, forming a notary chain responsible for cross-chain interaction and data transmission. This method leverages the inherent characteristics and security mechanisms of blockchain to address the centralization issue of notaries. A notary is randomly selected as an agent to perform conditional proxy re-encryption, transforming the shared ciphertext from supporting decryption by the data provider to supporting decryption by the data requester. The conditional proxy re-encryption key is generated by the data provider, thus preventing the leakage of the data provider's private key. The InterPlanetary File System (IPS) is linked to all blockchains. Data on each blockchain is encrypted and stored in the IPS, while key information such as the file fingerprint, related keys, and data hash of the data storage are encrypted and stored on the blockchain.

Description

Technical Field

[0001] This invention relates to a cross-chain data sharing scheme. By using a notary mechanism, introducing conditional proxy re-encryption technology, and combining the InterPlanetary File System, it transforms the non-supporting data sharing between blockchains into supporting data sharing. At the same time, it uses a random number calculation and comparison method to randomly determine the proxy and execute the conditional proxy re-encryption operation, which belongs to the field of blockchain technology. Background Technology

[0002] Based on node access criteria and openness, blockchains can be categorized into public blockchains, private blockchains, and consortium blockchains. In practical applications, each blockchain develops vertically and independently, with all transactions confined to its own chain. There is no business interaction between chains, resulting in a lack of trust and rendering many blockchain projects like isolated "information islands." While security is guaranteed, this approach is severely incompatible with the current trend of interconnectedness in society, and the development of single-chain systems will inevitably hinder the long-term development of blockchain. The lack of interoperability between blockchains greatly limits their application scope; therefore, achieving value interconnection between chains is a key focus of current blockchain research.

[0003] The notary mechanism is currently the cross-chain mechanism with the lowest implementation difficulty. Its principle is to use a trusted third-party intermediary to complete the reception, forwarding, and verification of cross-chain messages between two untrusted chains. This mechanism can automatically monitor events on different chains, determine the authenticity of on-chain events through a consensus mechanism, and respond promptly. It can also verify the signatures of received and forwarded cross-chain messages, ensuring the security and validity of cross-chain transactions.

[0004] Proxy re-encryption is an encryption technique that securely transforms ciphertext. Specifically, the proxy uses a re-encryption key to convert the ciphertext encrypted by the data provider into ciphertext that the data requester can decrypt. Conditional proxy re-encryption optimizes the granularity of proxy re-encryption, enabling fine-grained restrictions on the proxy's re-encryption operations. Specifically, it adds a condition value to traditional proxy re-encryption, requiring the proxy to meet this condition value before performing a re-encryption operation.

[0005] The InterPlanetary File System (IPS) is a network transmission protocol that supports distributed storage and file sharing. Its decentralized nature contributes to a more open and secure network operation. It integrates technologies such as distributed hash tables, the BitTorrent protocol, and the Git version control system, and links them to a blockchain to achieve permanent storage and sharing of data files. It supports various types of data storage and features versioning, content addressability, and data traceability. Using the IPS can alleviate the storage pressure on the blockchain, allowing the blockchain to store critical information and saving more storage space. Summary of the Invention

[0006] The purpose of this invention is to design a cross-chain data sharing scheme.

[0007] To achieve the above objectives, the technical solution of the present invention provides a cross-chain data sharing method, characterized by comprising the following steps:

[0008] Step 1: Each blockchain participating in cross-chain sharing contains numerous ordinary nodes, which are responsible for maintaining the routine operations of their respective blockchains. At the same time, all blockchains participating in cross-chain sharing are independent of each other and can only conduct intra-chain transactions, not cross-chain interactions.

[0009] Each blockchain is linked to the InterPlanetary File System (IPS), which leverages the distributed storage advantages of IPS to facilitate data upload and download between user nodes on different chains.

[0010] Step 2: Select some high-credit nodes from various blockchains to serve as notaries for cross-chain data sharing. The notaries form a notary chain, which is specifically responsible for cross-chain interaction tasks and data sharing between blockchains. Successful notaries need to pay a certain amount of deposit in order to carry out relevant cross-chain interaction work.

[0011] Step 3: When performing cross-chain interaction, a notary is randomly selected from the selected notary group through random number calculation and comparison to act as the agent for cross-chain interaction and be responsible for the conditional proxy re-encryption operation of the cross-chain interaction ciphertext.

[0012] When sharing data, the data requester issues a data sharing request. The notary on the notary chain verifies the data sharing request. After verification, the agent sends it to the data provider. The data provider parses the data sharing request and shares the target data with the data requester.

[0013] Preferably, in step 1, the routine work includes consensus among nodes and on-chain data storage.

[0014] Preferably, each node on the blockchain performs system initialization, determines fixed parameters for a specific scenario, obtains its own corresponding key, and possesses its own transaction data.

[0015] Preferably, in step 3, a verifiable secret sharing technique (k,n) is used during the random number calculation process, specifically including the following steps:

[0016] Step 3011: The system generates a random number share for each notary, then splits the random number share into n random number share sharers and broadcasts them to other notaries;

[0017] Step 3012: When each notary receives the random number share value from other notaries, they verify its legality, sign it after verification, and then broadcast it to other notaries.

[0018] Step 3013: When the notary gathers the shared value of random number shares verified and signed by k other notaries, a verified random number share can be synthesized and then broadcast to the other notaries.

[0019] Step 3014: After the notary receives k verified random number shares, he can calculate and synthesize a master random number, and then use this master random number and his own public key to calculate the hash value.

[0020] Step 3015: Compare the hash values ​​calculated by each notary public. The notary public with the smallest hash value is the agent to be determined.

[0021] Preferably, step 3, transferring shared data specifically includes the following steps:

[0022] Step 3021: The data requester publishes and signs a shared data request, and then submits it to the notary chain;

[0023] Step 3022: The notaries on the notary chain verify the authenticity of the shared data request and sign it. When the number of notary signatures on the shared data request exceeds 2 / 3 of the total number of notaries, it is considered legitimate and is sent to the data provider by the agent, along with the public key of the data requester.

[0024] Step 3023: After receiving the shared data request verified by the notary chain, the data provider parses the shared data request, understands the data requester's data needs, generates the corresponding random symmetric key, sets the re-encryption condition value corresponding to this data sharing, and generates the corresponding conditional proxy re-encryption key using its own private key, the data requester's public key, and the re-encryption condition value.

[0025] Step 3024: The data provider uses a random symmetric key to encrypt the shared data into ciphertext and stores it in the InterPlanetary File System (IPS), obtains the corresponding IPS file fingerprint, and then uses its own public key to encrypt key information, including the file fingerprint and the random symmetric key, into key ciphertext and embeds a re-encryption condition value. Then, the key ciphertext and the condition proxy re-encryption key are sent to the proxy.

[0026] Step 3025: The agent uses the conditional agent re-encryption key to re-encrypt the key ciphertext, obtains the new ciphertext, and forwards the new ciphertext to the data requester.

[0027] Step 3026: The data requester receives the new ciphertext, decrypts it using its private key to obtain the key information corresponding to the shared data, then downloads the corresponding shared data ciphertext from the InterPlanetary File System, decrypts it using a random symmetric key, and obtains the target shared data.

[0028] Step 3027: The data requester pays a certain amount of remuneration to the data provider and all notaries involved in cross-chain data sharing.

[0029] This invention selects high-trust nodes from various blockchains to act as notaries for cross-chain data sharing, forming a notary chain responsible for cross-chain interactions and data transfer. Leveraging the inherent characteristics and security mechanisms of blockchain, it addresses the centralization issue of notaries. A notary is randomly selected as an agent to perform conditional proxy re-encryption, transforming the shared ciphertext from supporting decryption by the data provider to supporting decryption by the data requester. The conditional proxy re-encryption key is generated by the data provider, thus preventing the leakage of their private key. The InterPlanetary File System (IPS) connects all blockchains, with data from each blockchain encrypted and stored within IPS. Key information such as the file fingerprint, related keys, and data hash of the data storage is encrypted and stored on-chain. This hybrid on-chain and off-chain storage model effectively reduces the storage pressure on the blockchain.

[0030] Compared with the prior art, the significant advantages of this invention are:

[0031] (1) This invention addresses the traditional notary mechanism and improves the selection and management of notaries. The notaries are high-credit nodes selected from various blockchains participating in cross-chain sharing, and all the notaries form a notary chain. The inherent characteristics and security mechanisms of the blockchain can solve the problem of the centralization of notaries.

[0032] (2) The present invention adopts a random determination method for the agent, which reduces the probability of the agent being targeted by attacks, thereby ensuring the security of cross-chain data sharing.

[0033] (3) The present invention adopts a hybrid storage mode combining blockchain and interplanetary file system to reduce the storage pressure of blockchain.

[0034] (4) This invention establishes a credit constraint and incentive strategy for notaries, namely, a notary who is successfully elected needs to pay a certain amount of deposit. At the same time, after the sharing is completed, the data requester needs to pay a certain amount of remuneration to the data provider and the notary, thereby providing incentives for ordinary nodes and notaries to participate in data sharing in good faith. Attached Figure Description

[0035] Figure 1This is a network architecture diagram of a cross-chain data sharing solution;

[0036] Figure 2 This is a flowchart of the cross-chain data sharing solution. Detailed Implementation

[0037] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0038] like Figure 1 As shown, the network architecture of the cross-chain data sharing method disclosed in this embodiment actually comprises three parts: the blockchains participating in cross-chain sharing, the notary chain composed of notaries, and the InterPlanetary File System (IPS) cluster. Each blockchain is associated with the IPS, leveraging the distributed storage advantages of the IPS to facilitate data upload and download by user nodes on different chains. For the security of shared data storage, user nodes need to encrypt the data before uploading it to the IPS. The file fingerprint and the random symmetric key used to encrypt the shared data are stored on their respective blockchains as a basis for future sharing traceability. The notary chain is composed of some high-credit nodes from each blockchain, and these selected nodes also act as notaries for cross-chain data sharing, specifically responsible for cross-chain interaction tasks and the transmission of shared data between blockchains.

[0039] like Figure 2As shown, the data requester initiates a data sharing request and attaches their signature to facilitate verification of its legitimacy by a notary on the notary blockchain. Upon receiving the data sharing request, the notary verifies and signs it. Once verified, the request and the data requester's public key are forwarded to the data provider. The data provider randomly generates a symmetric key to encrypt the shared data and uploads it to the InterPlanetary File System (IPS), obtaining the file fingerprint corresponding to the shared data. Simultaneously, a proxy re-encryption condition value is set, and the provider uses their public key to encrypt the file fingerprint, random symmetric key, and other key information into a key ciphertext, embedding it into the re-encryption condition value. This key ciphertext with the embedded condition value is first stored on the blockchain to ensure the immutability of the shared information. Then, using their private key, the data requester's public key, and the re-encryption condition value, a conditional proxy re-encryption key is generated. The key ciphertext and the generated conditional proxy re-encryption key are sent to the proxy. Upon receiving the key ciphertext and the conditional proxy re-encryption key, the proxy directly uses the conditional proxy re-encryption key to encrypt the key ciphertext into a new ciphertext and sends the new ciphertext to the data requester. After receiving the new ciphertext from the agent, the data requester can decrypt it using their private key to obtain the key information corresponding to the shared data. They then download the corresponding ciphertext based on the file fingerprint in the InterPlanetary File System (IPS), and finally decrypt it using a symmetric key to obtain the plaintext shared data. Finally, the data requester pays a certain amount of money to both the data provider and the notary.

Claims

1. A cross-chain data sharing method, characterized in that, Includes the following steps: Step 1: Each blockchain participating in cross-chain sharing contains numerous ordinary nodes, which are responsible for maintaining the routine operations of their respective blockchains. At the same time, all blockchains participating in cross-chain sharing are independent of each other and can only conduct intra-chain transactions, not cross-chain interactions. Each blockchain is linked to the InterPlanetary File System (IPS), which leverages the distributed storage advantages of IPS to facilitate data upload and download between user nodes on different chains. Step 2: Select some high-credit nodes from various blockchains to serve as notaries for cross-chain data sharing. The notaries form a notary chain, which is specifically responsible for cross-chain interaction tasks and data sharing between blockchains. Successful notaries need to pay a certain amount of deposit in order to carry out relevant cross-chain interaction work. Step 3: When performing cross-chain interaction, a notary is randomly selected from the selected notary group through random number calculation and comparison to act as the agent for cross-chain interaction and be responsible for the conditional proxy re-encryption operation of the cross-chain interaction ciphertext. When sharing data, the data requester issues a data sharing request. The notary on the notary chain verifies the data sharing request. After the verification is successful, the agent sends it to the data provider. The data provider parses the data sharing request and shares the target data with the data requester. The specific steps involved in transferring shared data are as follows: Step 3021: The data requester publishes and signs a shared data request, and then submits it to the notary chain; Step 3022: The notaries on the notary chain verify the authenticity of the shared data request and sign it. When the number of notary signatures on the shared data request exceeds 2 / 3 of the total number of notaries, it is considered legitimate and is sent to the data provider by the agent, along with the public key of the data requester. Step 3023: After receiving the shared data request verified by the notary chain, the data provider parses the shared data request, understands the data requester's data needs, generates the corresponding random symmetric key, sets the re-encryption condition value corresponding to this data sharing, and generates the corresponding conditional proxy re-encryption key using its own private key, the data requester's public key, and the re-encryption condition value. Step 3024: The data provider uses a random symmetric key to encrypt the shared data into ciphertext and stores it in the InterPlanetary File System (IPS), obtains the corresponding IPS file fingerprint, and then uses its own public key to encrypt key information, including the file fingerprint and the random symmetric key, into key ciphertext and embeds a re-encryption condition value. Then, the key ciphertext and the condition proxy re-encryption key are sent to the proxy. Step 3025: The agent uses the conditional agent re-encryption key to re-encrypt the key ciphertext, obtains the new ciphertext, and forwards the new ciphertext to the data requester. Step 3026: The data requester receives the new ciphertext, decrypts it using its private key to obtain the key information corresponding to the shared data, then downloads the corresponding shared data ciphertext from the InterPlanetary File System, decrypts it using a random symmetric key, and obtains the target shared data. Step 3027: The data requester pays a certain amount of gratitude to the data provider and all notaries involved in cross-chain data sharing.

2. The cross-chain data sharing method of claim 1, wherein, In step 1, the routine work includes consensus among nodes and on-chain data storage.

3. The cross-chain data sharing method of claim 1, wherein, Each node on the blockchain initializes its system, determines fixed parameters for a specific scenario, obtains its own key, and possesses its own transaction data.

4. The cross-chain data sharing method of claim 1, wherein, In step 3, a verifiable secret sharing technique (k,n) is used during the random number calculation process, specifically including the following steps: Step 3011: The system generates a random number share for each notary, then splits the random number share into n random number share sharers and broadcasts them to other notaries; Step 3012: When each notary receives the random number share value from other notaries, they verify its legality, sign it after verification, and then broadcast it to other notaries. Step 3013: When the notary gathers the shared value of random number shares verified and signed by k other notaries, a verified random number share can be synthesized and then broadcast to the other notaries. Step 3014: After the notary receives k verified random number shares, he can calculate and synthesize a master random number, and then use this master random number and his own public key to calculate the hash value. Step 3015: Compare the hash values ​​calculated by each notary public. The notary public with the smallest hash value is the agent to be determined.

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