A distributed oracle implementation method and system based on threshold signature

Abstract

The present invention belongs to the field of blockchain technology, and provides a distributed oracle implementation method and system based on threshold signature. The method is applied to the oracle network, including: receiving a request event sent by the blockchain to establish a TLS connection with a specified external data source; according to the request event, the nodes with private key shares use their own private key shares to sign to obtain their own signature shares, and broadcast; if the number of signature shares received by any node in the oracle network exceeds the threshold value t, a complete signature is constructed and sent to the blockchain; so that the blockchain uses the public key to verify the complete signature, and obtains the callback function specified by the user contract according to the request identifier, and executes the result of the callback function and returns it to the user contract; wherein, the private key share and public key are: the distributed key generation protocol is used to generate the private key share and public key for each node. The present invention will not restore the complete key during the signing process.

Description

Technical Field

[0001] The present invention belongs to the technical field of blockchain, and in particular to a distributed oracle implementation method and system based on threshold signature. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] The blockchain system is a closed system. In order to ensure the consistency of data on each node, the execution of smart contracts needs to produce deterministic and consistent results. If smart contracts are allowed to access external data, the execution results of smart contracts on each node may be inconsistent due to network fluctuations, node performance, and other reasons, making it impossible to reach a consensus. Therefore, smart contracts cannot actively obtain external data through network calls, access to the file system, and other operations. Some real-world needs require smart contracts to have the ability to access data in the real world, so an oracle is needed to obtain real-world data and input the data into the smart contract. The oracle can be regarded as a trusted intermediary for blockchain smart contracts to access external data, providing secure data feeding services for smart contracts and realizing data interoperability between on-chain and off-chain.

[0004] The oracle needs to protect the security of the process from obtaining data to returning it to the chain, and ensure the availability and integrity of the obtained data, that is, the data finally returned comes from the target data source and the data is not tampered with during the transmission process, and the requested external data is always accessible to avoid single point failure.

[0005] Provable, the original Oraclize project, started in 2015 and is one of the earliest oracle services used by Ethereum. Provable is a centralized oracle based on the TLSNotary protocol. It establishes a three-party TLS handshake between the data source, the auditor, and the audited party. The auditor and the audited party each hold a split TLS key share, and the auditor provides proof of data authenticity to prove that the data comes from the specified data source. Provable runs a customized open source system image on AWS as the auditor, and AWS can prove that the image has not been modified since it was instantiated. Provable has a single point of failure problem, and TLSNotary is only applicable to TLS1.0 and 1.1 versions.

[0006] Town Crier is the earliest proposed centralized TEE-based oracle solution. Town Crier uses TLS to ensure the security of the data transmission process between the oracle node and the data source, and uses the trusted execution environment provided by Intel SGX to protect the key negotiation and encryption and decryption of data packets in TLS, as well as the data processing and transaction construction after receiving the data to prevent the data from being tampered with in the chain process. However, Town Crier also has single point failure and scalability issues.

[0007] The Chinese patent application number "2020114580559" discloses a method and device for blockchain data on-chain based on threshold signatures and oracles, including an aggregation layer for distributing key shares for signatures of each node. When signing, each node first sends the key share to the aggregation layer, recovers the complete key at the aggregation layer, and then uses the key for signing. However, when the complete key is recovered at the aggregation layer, there is a possibility of key leakage during the signing process and the risk of single point failure of the aggregation layer.

[0008] To sum up, most of the existing oracle solutions are single-node oracle solutions that protect data security. Even multi-node oracle solutions have the possibility of key leakage during the signing process and the risk of single point failure in the aggregation layer. Summary of the invention

[0009] In order to solve the technical problems existing in the above-mentioned background technology, the present invention provides a distributed oracle implementation method and system based on threshold signature, which uses a distributed key generation protocol to generate key shares of each node, which are generated by negotiation of each node, without the need for a third-party aggregation layer to distribute keys. When signing, each node first generates its own signature share, and then broadcasts it to other nodes. Any node that receives a signature share exceeding the threshold value can construct a complete signature. The complete key will not be restored during the signing process, and no aggregation layer is required to construct a complete signature, avoiding the possibility of key leakage during the signing process and the risk of single-point failure of the aggregation layer.

[0010] In order to achieve the above object, the present invention adopts the following technical solution:

[0011] The first aspect of the present invention provides a method for implementing a distributed oracle based on threshold signatures.

[0012] A distributed oracle implementation method based on threshold signature, applied to an oracle network, comprising:

[0013] Receive request events sent by the blockchain to establish a TLS connection with the specified external data source;

[0014] According to the request event, the nodes with private key shares use their own private key shares to sign and obtain their own signature shares, and then broadcast;

[0015] If the number of signature shares received by any node in the oracle network exceeds the threshold value t, a complete signature is constructed and sent to the blockchain;

[0016] After the blockchain uses the public key to verify the complete signature, it obtains the callback function specified by the user contract according to the request identifier, and returns the result of executing the callback function to the user contract;

[0017] The private key share and public key are: a distributed key generation protocol is used to generate a private key share and a public key for each node.

[0018] Furthermore, the request event includes: a request identifier, an external data source address, and a request parameter, and the request identifier specifies a specific identifier ReqID for the blockchain request.

[0019] The second aspect of the present invention provides a method for implementing a distributed oracle based on threshold signatures.

[0020] A distributed oracle implementation method based on threshold signature, applied to blockchain, includes:

[0021] A distributed key generation protocol is used to generate a private key share and public key for each node;

[0022] According to the request of the user contract, a request event is sent to the oracle network, so that the oracle network establishes a TLS connection with the specified external data source according to the request event, signs the request event with their respective private key shares to obtain their respective signature shares, and broadcasts them;

[0023] Receive the complete signature sent by the oracle network, where the complete signature is constructed when the number of signature shares received by any node in the oracle network exceeds the threshold value t;

[0024] After the complete signature is verified using the public key, the callback function specified by the user contract is obtained according to the request identifier, and the result of executing the callback function is returned to the user contract.

[0025] Furthermore, the request event includes: a request identifier, an external data source address, and a request parameter, wherein the request identifier specifies a specific identifier ReqID for the blockchain request;

[0026] The third aspect of the present invention provides a distributed oracle implementation system based on threshold signatures.

[0027] A distributed oracle implementation system based on threshold signatures, on which a computer program is stored. When the program is executed by a processor, it implements the distributed oracle implementation method based on threshold signatures as described in the first aspect or implements the steps in the distributed oracle implementation method based on threshold signatures as described in the second aspect.

[0028] A fourth aspect of the present invention provides a computer-readable storage medium.

[0029] A computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the distributed oracle implementation method based on threshold signature as described in the first aspect or implements the steps in the distributed oracle implementation method based on threshold signature as described in the second aspect.

[0030] A fifth aspect of the present invention provides a computer device.

[0031] A computer device comprises a memory, a processor and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the distributed oracle implementation method based on threshold signature as described in the first aspect or the steps in the distributed oracle implementation method based on threshold signature as described in the second aspect are implemented.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] TLS is used between the oracle node and the external data source to ensure the security of the data transmission process. SGX is used to ensure that the data will not be tampered with during the process of the oracle node obtaining the data, processing the data and constructing the transaction chain. At the same time, the remote proof function provided by SGX can verify whether the new node is trustworthy when the new node joins.

[0034] Using multiple oracle nodes to form an oracle network avoids the problem of single point failure of nodes; using a distributed key generation protocol to generate a private key share for each node avoids the introduction of a trusted third party; using threshold signatures to reach consensus on request data between nodes avoids the performance problems caused by all nodes directly uploading request data to the chain and having contracts perform data processing, aggregation and verification. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0036] Figure 1 It is a flow chart of the distributed oracle implementation method based on threshold signature shown in the present invention. DETAILED DESCRIPTION

[0037] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0038] It should be noted that the following detailed descriptions are all illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0039] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0040] It should be noted that the flowcharts and block diagrams in the accompanying drawings illustrate the possible implementation architecture, functions and operations of the methods and systems according to various embodiments of the present disclosure. It should be noted that each box in the flowchart or block diagram can represent a module, a program segment, or a part of a code, and the module, program segment, or a part of a code may include one or more executable instructions for implementing the logical functions specified in each embodiment. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in an order different from that marked in the accompanying drawings. For example, two boxes represented in succession can actually be executed substantially in parallel, or they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the flowchart and / or block diagram, and the combination of boxes in the flowchart and / or block diagram can be implemented using a dedicated hardware-based system that performs a specified function or operation, or can be implemented using a combination of dedicated hardware and computer instructions.

[0041] Embodiment 1

[0042] like Figure 1 As shown, this embodiment provides a distributed oracle implementation method based on threshold signature, and the method includes the following steps:

[0043] Receive request events sent by the blockchain to establish a TLS connection with the specified external data source;

[0044] According to the request event, the nodes with private key shares use their own private key shares to sign and obtain their own signature shares, and then broadcast;

[0045] If the number of signature shares received by any node in the oracle network exceeds the threshold value t, a complete signature is constructed and sent to the blockchain;

[0046] After the blockchain uses the public key to verify the complete signature, it obtains the callback function specified by the user contract according to the request identifier, and returns the result of executing the callback function to the user contract;

[0047] The private key share and public key are: a distributed key generation protocol is used to generate a private key share and a public key for each node.

[0048] Embodiment 2

[0049] This embodiment provides a method for implementing a distributed oracle based on threshold signatures.

[0050] A distributed oracle implementation method based on threshold signature, applied to blockchain, includes:

[0051] A distributed key generation protocol is used to generate a private key share and public key for each node;

[0052] According to the request of the user contract, a request event is sent to the oracle network, so that the oracle network establishes a TLS connection with the specified external data source according to the request event, signs the request event with their respective private key shares to obtain their respective signature shares, and broadcasts them;

[0053] Receive the complete signature sent by the oracle network, where the complete signature is constructed when the number of signature shares received by any node in the oracle network exceeds the threshold value t;

[0054] After the complete signature is verified using the public key, the callback function specified by the user contract is obtained according to the request identifier, and the result of executing the callback function is returned to the user contract.

[0055] The substantive contents adopted in Example 1 and Example 2 are the same. Here, the specific implementation schemes of Example 1 and Example 2 are introduced. The whole scheme includes three parties: blockchain, oracle service, and external data source.

[0056] The trusted execution environment in the solution is provided by Intel SGX technology. SGX provides remote attestation capabilities that can verify that the code and data protected in the trusted environment have not been tampered with.

[0057] The threshold signature in the scheme uses the BLS threshold signature scheme, which can be roughly divided into four stages: key distribution, signature, recovery of complete signature, and signature verification. This scheme uses a distributed key generation protocol in the key distribution stage, which can calculate the respective private key shares and the public key for verifying the complete signature for each node without the need for a trusted third party. In the signing stage, multiple parties with private key shares can generate their own signature shares, and a complete signature can be constructed with more than the threshold value t signature shares. In the signature verification stage, the signature can be verified using the public key generated in the key generation stage.

[0058] The implementation of the oracle service includes two parts: on-chain and off-chain. The off-chain part is a oracle network composed of multiple oracle nodes, each of which runs in a trusted execution environment provided by Intel SGX, responsible for listening to various events released by the on-chain oracle contract, performing distributed key generation, obtaining data, signing data to generate their own signature shares and constructing complete signatures, constructing transactions on the chain, etc. The on-chain part consists of multiple oracle contracts, including: the node management contract NodeManagerContract, which is used to record the information of each node in the current oracle network, such as the account address and network address of the node on the chain, and provides new node registration and node information query methods; the key management contract KeyManagerContract, which is used to store the public key generated by the distributed key generation protocol executed by the entire oracle network for verifying the complete signature, and calculate the threshold value according to the number of current oracle nodes; the oracle contract OracleContract, which is used to provide a method for requesting external data to the user contract and a method for returning data to the oracle node.

[0059] New node joining: When a new oracle node joins, it first needs to execute the registration method Transaction(NodeManagerContract.Register, AccountAddr, NetAddr) provided by the above node management contract to register its own blockchain account address and network address. The node management contract publishes a registration event log RegisterEvent(AccountAddr, NetAddr) containing the new node account address and network address. After the existing oracle node listens to the registration event, it initiates a remote proof request to the new node. The new node generates an SGX remote proof for other nodes to verify. After the verification passes, the new node joins the oracle network. The node management contract stores the identity information of the new node. The key management contract calculates the threshold value t and publishes the key generation event KeyGenEvent(t). After the node listens to the event, it executes the distributed key generation protocol, regenerates the private key share KeySharei of each node and the public key PubKey used to verify the complete signature. After any node puts the public key on the chain, other nodes no longer put the public key on the chain, but only need to verify whether the public key on the chain is correct. If the node finds that the public key on the chain is different from the locally generated public key, it executes the public key dispute method Transaction(KeyManagerContract.Diapute, AccountAddr) provided by the key management contract. When the number of nodes that dispute the correctness of the current public key exceeds the threshold, the distributed key generation protocol is re-executed.

[0060] User contract requests external data: The external data source can be any data source that can be accessed through TLS. When the user contract needs to obtain external data, it calls the external data request method provided by the above oracle contract, passing in the external data source address, request parameters, and callback function Transaction(OracleContract.Request, ReqAddress, ReqParams, CallbackFunc). The oracle contract specifies a specific identifier ReqID for the request and stores the request. At the same time, it publishes an event log RequestEvent(ReqID, ReqAddress, ReqParams) containing the identifier, external data source address, and request parameters. After the oracle node listens to the event, it executes the request, establishes a TLS connection with the specified external data source, obtains data according to the request parameters, and uses their respective private key shares to sign to obtain their respective signature shares Signi, and then each node broadcasts their own calculated The signature share, according to the principle of threshold signature, when the number of identical signature shares received by any node in the oracle network exceeds the threshold value t, the complete signature Sign can be calculated. The first node that calculates the complete signature broadcasts the complete signature, notifies other nodes to stop the calculation and constructs a transaction to call the return data method provided by the oracle contract to upload the result and the complete signature to the chain Transaction(OracleContract.Response, ReqID, Result, Sign). After receiving the result and signature, the oracle contract uses the public key stored in the key management contract for verification. After the verification is passed, the callback function specified by the user contract is obtained according to the request identifier ReqID, and the callback function is executed to return the result to the user contract Transaction(UserContract.CallbackFunc, Result).

[0061] Embodiment 3

[0062] This embodiment provides a distributed oracle implementation system based on threshold signatures.

[0063] A distributed oracle implementation system based on threshold signatures, on which a computer program is stored. When the program is executed by a processor, it implements the distributed oracle implementation method based on threshold signatures as described in Example 1 or implements the steps in the distributed oracle implementation method based on threshold signatures as described in Example 2.

[0064] Embodiment 4

[0065] This embodiment provides a computer-readable storage medium having a computer program stored thereon. When the program is executed by a processor, it implements the distributed oracle implementation method based on threshold signature as described in Embodiment 1 or implements the steps in the distributed oracle implementation method based on threshold signature as described in Embodiment 2.

[0066] Embodiment 5

[0067] This embodiment provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, it implements the distributed oracle implementation method based on threshold signature as described in Example 1 or implements the steps in the distributed oracle implementation method based on threshold signature as described in Example 2.

[0068] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of hardware embodiments, software embodiments, or embodiments combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage and optical storage, etc.) containing computer-usable program code.

[0069] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0070] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0071] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0072] A person skilled in the art can understand that all or part of the processes in the above-mentioned embodiments can be implemented by instructing the relevant hardware through a computer program, and the program can be stored in a computer-readable storage medium, and when the program is executed, it can include the processes of the embodiments of the above-mentioned methods. The storage medium can be a disk, an optical disk, a read-only memory (ROM) or a random access memory (RAM), etc.

[0073] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. 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 distributed oracle implementation method based on threshold signature, characterized in that: Applied to oracle networks, including: Receive request events sent by the blockchain to establish a TLS connection with the specified external data source; According to the request event, the nodes with private key shares use their own private key shares to sign and obtain their own signature shares, and then broadcast; If the number of signature shares received by any node in the oracle network exceeds the threshold value t, a complete signature is constructed and sent to the blockchain; After any node uploads the public key to the chain, other nodes no longer upload the public key to the chain, and only need to verify whether the public key that has been uploaded is correct; if the node finds that the public key uploaded is different from the public key generated locally, the public key dispute method provided by the key management contract is executed; when the number of nodes that dispute the correctness of the current public key exceeds the threshold, the distributed key generation protocol is re-executed; After the blockchain uses the public key to verify the complete signature, it obtains the callback function specified by the user contract according to the request identifier, and returns the result of executing the callback function to the user contract; The private key share and public key are: a distributed key generation protocol is used to generate a private key share and a public key for each node; When a new oracle node joins, the registration method provided by the node management contract is executed to register the blockchain account address and network address of the node. The node management contract publishes a registration event log containing the new node account address and network address. After the existing oracle node listens to the registration event, it initiates a remote proof request to the new node. The new node generates an SGX remote proof for other nodes to verify. After the verification passes, the new node joins the oracle network. The node management contract stores the identity information of the new node. The key management contract calculates the threshold value t and publishes a key generation event. After the node listens to the event, it executes the distributed key generation protocol to regenerate the private key share of each node and the public key used to verify the complete signature.

2. The distributed oracle implementation method based on threshold signature according to claim 1 is characterized in that: The request event includes: a request identifier, an external data source address, and a request parameter, wherein the request identifier specifies a specific identifier ReqID for the blockchain request.

3. The distributed oracle implementation method based on threshold signature according to claim 1 is characterized in that: The blockchain includes: The node management contract is used to record the information of each node in the current oracle network, and provides methods for registering new nodes and querying node information; The key management contract is used to store the key generated by the distributed key generation protocol executed by the entire oracle network for verification. The public key of the complete signature and the threshold value calculated based on the current number of oracle nodes; The oracle contract is used to provide the user contract with a method for requesting external data and to provide the oracle node with a method for returning data.

4. A distributed oracle implementation method based on threshold signature, characterized in that: Applications in blockchain include: A distributed key generation protocol is used to generate a private key share and public key for each node; According to the request of the user contract, a request event is sent to the oracle network, so that the oracle network establishes a TLS connection with the specified external data source according to the request event, signs the request event with their respective private key shares to obtain their respective signature shares, and broadcasts them; Receive the complete signature sent by the oracle network, where the complete signature is constructed when the number of signature shares received by any node in the oracle network exceeds the threshold value t; After any node uploads the public key to the chain, other nodes no longer upload the public key to the chain, and only need to verify whether the public key that has been uploaded is correct; if the node finds that the public key uploaded is different from the public key generated locally, the public key dispute method provided by the key management contract is executed; when the number of nodes that dispute the correctness of the current public key exceeds the threshold, the distributed key generation protocol is re-executed; After the complete signature is verified using the public key, the callback function specified by the user contract is obtained according to the request identifier, and the result of executing the callback function is returned to the user contract; When a new oracle node joins, the registration method provided by the node management contract is executed to register the blockchain account address and network address of the node. The node management contract publishes a registration event log containing the new node account address and network address. After the existing oracle node listens to the registration event, it initiates a remote proof request to the new node. The new node generates an SGX remote proof for other nodes to verify. After the verification passes, the new node joins the oracle network. The node management contract stores the identity information of the new node. The key management contract calculates the threshold value t and publishes a key generation event. After the node listens to the event, it executes the distributed key generation protocol to regenerate the private key share of each node and the public key used to verify the complete signature.

5. The distributed oracle implementation method based on threshold signature according to claim 4 is characterized in that: The request event includes: a request identifier, an external data source address, and a request parameter, wherein the request identifier specifies a specific identifier ReqID for the blockchain request; Or, the blockchain includes: The node management contract is used to record the information of each node in the current oracle network, and provides methods for registering new nodes and querying node information; The key management contract is used to store the public key generated by the distributed key generation protocol executed by the entire oracle network for verifying the complete signature, and calculate the threshold value based on the current number of oracle nodes; The oracle contract is used to provide the user contract with a method for requesting external data and to provide the oracle node with a method for returning data.

6. A distributed oracle implementation system based on threshold signature, on which a computer program is stored, characterized in that: When the program is executed by a processor, it implements the distributed oracle implementation method based on threshold signature as described in any one of claims 1-3 or implements the steps in the distributed oracle implementation method based on threshold signature as described in any one of claims 4-5.

7. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, it implements the distributed oracle implementation method based on threshold signature as described in any one of claims 1-3 or implements the steps in the distributed oracle implementation method based on threshold signature as described in any one of claims 4-5.

8. A computer device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the program, it implements the distributed oracle implementation method based on threshold signature as described in any one of claims 1-3 or implements the steps in the distributed oracle implementation method based on threshold signature as described in any one of claims 4-5.

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