KR102123320B1 - Smart Contract System and Smart Contract method - Google Patents

Abstract

Disclosed is a smart contract system and method. In a smart contract method according to an aspect, a seller node registers a sale on a blockchain, and in a state in which a professional member node participates, the seller node negotiates a contract for the sale with the buyer node to prepare an electronic contract, , Verifying the legal validity of the created electronic contract, verifying the smart contract code corresponding to the electronic contract by the seller node, and extracting and extracting personal information and sensitive information from the electronic contract by the seller node De-identifying and encrypting personal information and sensitive information, and storing the electronic contract in which the seller node has personal information and sensitive information de-identified and encrypted in a distributed data storage, and wherein the seller node stores the electronic contract. It may include the step of registering in the blockchain.

Description

Smart contract system and smart contract method

It is related to blockchain-based smart contract technology.

Initially, blockchain has received attention as a technology for storing cryptocurrency, but it is currently receiving attention as a technology utilized as a platform through a smart contract of blockchain. Smart contracts can be defined as a protocol that complies with highly developed contracts in a trusted computer Internet environment. Smart contracts are a type of contract that implements certain conditions as executable code. In Ethereum, they can be distributed to blockchains through transactions. Ethereum is a kind of cryptocurrency system based on blockchain, and is building an environment that can efficiently distribute and execute smart contracts. In Ethereum, there are externally owned accounts controlled by secret keys and contract accounts controlled by code, and users create transactions through externally owned accounts to distribute smart contracts, or You can run the code included in the smart contract.

In the case of using a smart contract in the field of electronic contracts, in order for a contract having a legal effect to be established, information that can identify individuals between contracting parties, that is, personal information is required, in which case, personal information is stored in a block. However, if such personal information is recorded in plain text on the blockchain, the information stored on the blockchain is basically disclosed to all participants participating in the network, so confidential data and personal information registered on the blockchain may be unintentionally disclosed. There is a risk.

Republic of Korea Registered Patent Publication No. 10-1849917 (May 31, 2018)

It is an object of the present invention to provide a smart contract system and method that can solve information protection problems that may occur in a blockchain-based smart contract.

In a smart contract method according to an aspect, a seller node registers a sale on a blockchain, and in a state in which a professional member node participates, the seller node negotiates a contract for the sale with the buyer node to prepare an electronic contract, , Verifying the legal validity of the created electronic contract, verifying the smart contract code corresponding to the electronic contract by the seller node, and extracting and extracting personal information and sensitive information from the electronic contract by the seller node De-identifying and encrypting personal information and sensitive information, and storing the electronic contract in which the seller node has personal information and sensitive information de-identified and encrypted in a distributed data storage, and wherein the seller node stores the electronic contract. It may include the step of registering in the blockchain.

The professional member node may be a node for legal advice on the contract.

In the step of verifying the legal validity, the seller node opens a side channel at the request of the buyer node, and the seller node engages with the buyer node through the side channel under the participation of the professional member node Negotiating, and when the seller node negotiates the contents of the contract, the open side channel is terminated, and the seller node stores the conversations generated on the side channel in a distributed data storage, and the seller The node may include generating an electronic contract and verifying the legal validity of the generated electronic contract.

The side channel may be a state channel of Ethereum.

The opening and closing of the side channel may be performed through the private key signature of the seller node and the buyer node.

In the step of verifying the smart contract code, the seller node may perform at least one of a cross-compatibility check, execution code verification, and transaction validation so that no error occurs in the code when the smart contract code is executed.

The smart contract method may further include a step in which the seller node calls a controller node to resolve the error when the smart contract code verification error occurs.

The controller node may be a node that mediates and audits transactions and detects abnormalities on the blockchain network to normalize transactions.

The step of de-identifying and encrypting may further include the step of the seller node notifying the information subject of the presence or absence of the personal information and the sensitive information, and receiving consent from the information subject to use the information. .

The step of de-identifying and encrypting may further include the step of setting, by the seller node, an expiration date for the use of information according to an instruction of the information subject for the encrypted and de-identified information.

The smart contract method may further include granting a role to each node constituting the blockchain network through an application or a server.

The step of granting the role includes assigning a role of a normal user node to a node that has undergone primary authentication, and a seller node, a buyer node, a professional member node, or a controller to a node that has undergone secondary authentication after primary authentication. It may further include the step of granting the role of one of the nodes.

The primary authentication is to register a wallet address, and the secondary authentication may be to authenticate a real name.

The primary authentication is to sign up for an application or server, and the secondary authentication can be to register a wallet address and to authenticate a real name.

The authority for each role can be implemented as one smart contract.

When executing smart contracts and smart contracts, the risk of disclosure of personal and sensitive information can be eliminated.

1 is a block diagram showing an embodiment of a smart contract system.
2 is a flowchart illustrating an embodiment of a method of assigning a role on a blockchain network to a node.
3 is a flowchart illustrating another embodiment of a method of assigning a role on a blockchain network to a node.
4 is a flowchart illustrating an embodiment of a smart contract method.
5 is a flowchart illustrating an embodiment of a method for registering a sale in a blockchain.
6 is a flowchart illustrating an embodiment of a method for negotiating a contract between a seller node and a buyer node.
7 is a flowchart illustrating an embodiment of a method of protecting personal information and sensitive information.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that in adding reference numerals to the components of each drawing, the same components have the same reference numerals as possible even though they are displayed on different drawings. In addition, in the description of the present invention, when it is determined that the detailed description of the related known functions or configurations may unnecessarily obscure the subject matter of the present invention, the detailed description will be omitted.

On the other hand, for each step, each step may occur differently from the order specified unless a specific order is explicitly stated in the context. That is, each step may be performed in the same order as specified, may be performed substantially simultaneously, or may be performed in the reverse order.

Terms to be described later are terms defined in consideration of functions in the present invention, which may vary according to a user's or operator's intention or practice. Therefore, the definition should be made based on the contents throughout this specification.

Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. The terms are only used to distinguish one component from other components. Singular expressions include plural expressions unless the context clearly indicates otherwise, and terms such as'include' or'have' include features, numbers, steps, actions, components, parts, or combinations thereof. It should be understood that it is intended to designate the existence of one, and does not preclude the existence or addition possibility of one or more other features or numbers, steps, operations, components, parts or combinations thereof.

In addition, the division of the components in the present specification is only divided by the main functions of each component. That is, two or more components may be combined into one component, or one component may be divided into two or more for each subdivided function. In addition, each of the constituent parts may additionally perform some or all of the functions of other constituent parts in addition to the main functions of the constituent parts, and some of the main functions of each constituent part are dedicated by other constituent parts It may be performed. Each component may be implemented in hardware or software, or a combination of hardware and software.

1 is a block diagram showing an embodiment of a smart contract system.

The smart contract system 100 according to an embodiment may perform a reliable smart contract method based on a blockchain in consideration of personal information protection and information protection.

Referring to FIG. 1, the smart contract system 100 may include a plurality of nodes 110.

The plurality of nodes 110 may be interconnected to form a blockchain network 10. The blockchain network 10 may mean a P2P distributed network composed of a plurality of nodes 110 storing a distributed ledger of the blockchain. Since the blockchain network 10 is configured such that at least some of the nodes 110 can perform the same processing, even if some of the nodes 110 are shut down or tampered with, the entire system may not be affected. The node 110 may mean any computing device connected to the blockchain network 10. The node 110 may include a digital wallet, a blockchain copy, a verification engine, a mining engine, and a P2P network distribution function.

According to an embodiment, the blockchain network 10 may be a consortium blockchain network. That is, each node 110 may participate in the blockchain network 10 through a subscription and authentication procedure.

The blockchain network 10 can verify the transactions made by each node 110, generate a block including a transaction using a consensus algorithm, and share the generated block across the network to reflect it on the blockchain. At this time, the consensus algorithm includes PoW (Proof of Work), PoS (Proof of Stake), DPoS (Delegated Proof of Stake), PoI (Proof of Importance), PBFT (Practical Byzantine Fault Tolerance), Tendermint (DPoS + PBFT), etc. It can contain.

Each node 110 may be assigned a role on the blockchain network 10 through a subscription and authentication procedure. According to an embodiment, each node 110 may be assigned a role according to membership registration, wallet address registration, or additional authentication of a user through an application installed on each node 110 or a predetermined server.

According to one embodiment, the smart contract system 100 verifies using the wallet address of the node 110 of the blockchain network 10, and each node 110 is assigned to a role (general user, seller, buyer) , Professional members, controllers). The smart contract system 100 assigns a role to each node 110 and then, when a user accesses the contract information, if the contract information includes sensitive information or personal information, after verifying whether the user is accessible, access Appropriate authority can be given to whether and to which operation is available.

Table 1 shows an example of a role and authority of a node.

According to an embodiment, authority according to the role of the node 110 may be implemented and used as a single smart contract. Through this, it can be applied according to the rules set without exception, and if it is necessary to change the status, it can be managed by updating the status of the contract.

2 is a flowchart illustrating an embodiment of a method of assigning a role on a blockchain network to a node.

Referring to FIG. 2, the node 110 may perform primary authentication by registering a user's wallet address through the application or server 120 (210 ). The application or the server 120 may register the user's wallet address to grant the normal user role to the node 110 whose primary authentication is completed (220 ).

The node 110 that has been granted a general user role may register itself as a general user on the blockchain 130. For example, the node 110 can register itself as a general user on the blockchain 130 by creating a role registration transaction and sharing the role registration transaction with all nodes on the blockchain network.

If the node 110 wants to participate directly in the contract, the node 110 may perform secondary authentication of additional authentication (eg, real-name authentication) through the application or server 120 (250 ).

The application or the server 120 may grant the role of a seller, a buyer, a professional member, or a controller 250 to the node 110 whose secondary authentication is completed according to the selection of the node 110 (250 ).

The node 110, which has been granted the role of a seller, a buyer, a professional member, or a controller, may register itself as a seller, a buyer, a professional member, or a controller in the blockchain 130. For example, the node 110 may register itself as a seller, buyer, professional member, or controller in the blockchain 130 by sharing the role registration transaction with all nodes on the blockchain network by creating a role registration transaction.

3 is a flowchart illustrating another embodiment of a method of assigning a role on a blockchain network to a node. Unlike the FIG. 2, the embodiment of FIG. 3 cannot participate in a blockchain network in the case of a general user node. That is, the general user node can only search for the property registered in the application or the server 120 through the application or the server 120, and cannot directly participate in the blockchain network.

Referring to FIG. 3, the node 110 may perform primary authentication by performing membership registration of the application or server 120 through the application or server 120 (310 ).

The application or the server 120 may grant a normal user role to the node 110, which has completed primary authentication through membership registration (320).

If the node 110 wants to directly participate in the contract through the blockchain network, the node 110 performs secondary authentication by registering the wallet address and additional authentication (eg, real name authentication) through the application or the server 120. It can be performed (330).

The application or the server 120 may grant a role of a seller, a buyer, a professional member, or a controller (340) to the node 110 whose secondary authentication is completed according to the selection of the node 110.

The node 110, which has been granted the role of a seller, a buyer, a professional member, or a controller, may register itself as a seller, a buyer, a professional member, or a controller in the blockchain 130. For example, the node 110 may register itself as a seller, buyer, professional member, or controller in the blockchain 130 by sharing the role registration transaction with all nodes on the blockchain network by creating a role registration transaction.

4 is a flowchart illustrating an embodiment of a smart contract method. The smart contract method of FIG. 4 may be performed by the smart contract system 100 of FIG. 1.

Referring to FIG. 4, the seller node 111 may register the sale with the blockchain 130 through an application or a server (410). For example, the seller node 111 may register the sale on the blockchain 130 by inputting the sale information through an application or a server and creating a sale registration transaction to share the sale registration transaction with all nodes on the blockchain network. have.

The purchaser node 112 may search for a listing registered in the blockchain 130 and view the listing information (420 ).

The buyer node 112 who wants to purchase a registered product on the blockchain 130 can negotiate the contents of the sales contract with the seller node 111 to create an electronic contract and verify the legal validity of the electronic contract (430) ). At this time, if necessary, the seller node 111 and the buyer node 112 may call a professional member node, and negotiate the contents of the contract with the participation of the professional member node, prepare an agreement electronic contract, and verify the legal validity of the electronic contract. . At this time, as described in Table 1, the professional member node is a node for legal advice on legal matters, and can perform legal advice and review contract contents.

According to an embodiment, negotiation of the contents of the sales contract between the seller node 111 and the buyer node 112 may be performed through a side channel (eg, a state channel of Ethereum) separate from the main channel. . Negotiation of the contents of the trading contract can include sensitive content, so there is no need to make it in the main blockchain network where all nodes participate. Therefore, according to one embodiment, the negotiation of the contents of the sales contract between the seller node 111 and the buyer node 112 is performed in the side channel, and the negotiation contents are signed with the private key of the participant, such as distributed data storage (for example, IPFS (Inter -Planetary File System) or Swarm), you can expect the integrity and non-repudiation of data and reduce unnecessary fees due to transaction occurrence.

On the other hand, the electronic contract is a contract variable (for example, identification information of the party (name, social security number, address, phone number, etc.), contract terms and contents (amount, date, etc.) so that the user can easily create it without writing a code. Etc.).

When the electronic contract is completed between the seller node 111 and the buyer node 112, the seller node 111 may verify the smart contract code (440). According to an embodiment, the seller node 111 may perform a cross-compatibility check, execution code verification, transaction validation, data/transaction format verification, and the like so that the smart contract code corresponding to the electronic contract can be executed without error. .

Most people who actually participate in the contract are not programmable. Accordingly, according to an embodiment, the smart contract system may implement a standard contract in the form of a smart contract, and create an electronic contract based on the contract variable received from the HTML page written in the contract form. Each contract is not distributed every time as a smart contract, and the entered data can be stored on the blockchain to ensure integrity. Each contract can be loaded into a pre-distributed smart contract and stored therein. Accordingly, the smart contract system may perform cross-compatibility check, execution code verification, transaction validation, and data/transaction format verification, so that errors in the code do not occur when the smart contract code is executed due to the input data.

As a result of verifying the smart contract code, the seller node 111 may call the controller node to resolve the error (450). At this time, as shown in Table 1, the controller node can arbitrate and audit transactions, detect anomalies in the convex chain network, perform transaction normalization, and mediate them in the event of a dispute between contracting parties.

The seller node 111 may extract personal information and sensitive information from the electronic contract, and apply the de-identification and/or encryption to the extracted personal information and sensitive information and store it in a distributed data storage (eg, IPFS or Swarm). (460). At this time, the seller node 111 may notify the information subject of this fact and receive additional consent for the use of the information. In addition, the seller node 111 may evaluate the adequacy of information on the encrypted and de-identified information, and then set a validity period for using the information according to the command of the information subject. At this time, if there is no command from the information subject, a predetermined period (eg, information retention period according to laws and regulations) may be set as an effective period for information use.

Meanwhile, the personal information and sensitive information that have expired for the use of information can be logically deleted in the following two ways.

First, by using the delete function provided by Ethereum, it is possible to delete personal information and sensitive information that have passed the validity period. In this case, asset information can be logically deleted through the delete function provided by Ethereum, and the value of EVM (Ethereum Virtual Machine) Storage can be initialized.

Second, it is possible to delete personal information and sensitive information whose validity period has expired by deleting the reference address value for personal information stored in the distributed data storage. In this case, the reference address of the distributed data storage where the actual information is stored can be deleted so that the data stored in the distributed data storage can no longer be retrieved from the corresponding smart contract.

The seller node 111 may register the electronic contract with the blockchain 130 (470). For example, the seller node 111 may register an electronic contract in the blockchain 130 by creating a contract registration transaction and sharing the contract registration transaction with all nodes on the blockchain network.

Meanwhile, in FIG. 4, the smart contract code verification 440, the controller node call 450 in case of an error, the de-identification and encryption of personal information and sensitive information 460, and the electronic contract registration 470 are seller nodes 111. Is described as performing, but is not limited thereto. That is, the above-described processes 440, 450, 460, and 470 may be performed by the buyer node 112, or may be performed by both the seller node 111 and the buyer node 112.

5 is a flowchart illustrating an embodiment of a method for registering a sale in a blockchain. The property registration method of FIG. 5 may be an embodiment of step 410 of FIG. 4.

Referring to FIG. 5, the seller node may create the sale information through an application or a server (410).

The seller node may determine whether there is personal information or sensitive information in the created sale information (520), and if there is personal information or sensitive information, the personal information or sensitive information may be de-identified and encrypted and stored in a distributed data storage (530). ). In addition, the seller node may register the sale on the blockchain 130 by sharing the sale registration transaction with all nodes on the blockchain network by creating a sale registration transaction (540).

6 is a flowchart illustrating an embodiment of a method for negotiating a contract between a seller node and a buyer node. The consultation method of FIG. 6 may be an embodiment of step 430 of FIG. 4.

Referring to FIG. 6, the buyer node 112 signs the private channel with the private key to request the seller node 111 to open the side channel (610), and the seller node 111 accepts the side channel open request and the user It can be signed with the private key of (620). The seller node 111 may open the side channel and request participation of the professional member node to the professional member node as needed (630).

The seller node 111 and the buyer node 112 may negotiate the contents of the contract through the side channel with the participation of the professional member node (640). At this time, the professional member node may provide legal advice to the seller node 111 and the buyer node 112 in the process of negotiating the contents of the contract.

The seller node 111 may sign with its own private key when negotiation of the contract is completed, and terminate the side channel when the buyer node 112 signs with the private key (650).

The seller node 111 may hash all the conversations that have occurred on the side channel and store them in a distributed data store (660).

The seller node 111 checks the final contract and signs it with its own private key, and the buyer node 112 signs it with the private key to create an electronic contract, and validates the legal validity of the electronic contract according to the advice of a professional member node Can (670).

7 is a flowchart illustrating an embodiment of a method of protecting personal information and sensitive information. The method of protecting personal information and sensitive information of FIG. 7 may be an embodiment of step 460 of FIG. 4.

Referring to FIG. 7, the seller node may analyze the electronic contract (710 ), and determine whether personal information or sensitive information is included in the electronic contract (720 ).

If it is determined that the seller node contains personal information or sensitive information in the electronic contract, the seller node may extract personal information or sensitive information to perform de-identification and encryption (730). At this time, the seller node may notify the information subject of the presence or absence of personal information or sensitive information, and receive additional consent for the use of information from the information subject.

The seller node may set an expiration date for the use of the information according to the command of the information subject for the encrypted and de-identified information (740 ). At this time, if there is no command from the information subject, a predetermined period (eg, information retention period according to laws and regulations) may be set as an effective period for information use.

The seller node may store the electronic contract in a distributed data store after de-identifying and encrypting personal information or sensitive information (750).

On the other hand, the electronic contract stored in this way can confirm the requesting subject and the authority of the subject, check the validity period for the use of the information, and then check again in plain text form when all the conditions are satisfied.

One aspect of the present invention can be embodied as computer readable code on a computer readable recording medium. The codes and code segments that implement the above program can be easily inferred by computer programmers in the art. The computer-readable recording medium may include any kind of recording device in which data readable by a computer system is stored. Examples of the computer-readable recording medium may include ROM, RAM, CD-ROM, magnetic tape, floppy disk, optical disk, and the like. In addition, the computer-readable recording medium can be distributed over network coupled computer systems so that the computer-readable code is written and executed in a distributed fashion.

So far, the present invention has been focused on the preferred embodiments. Those skilled in the art to which the present invention pertains will understand that the present invention may be implemented in a modified form without departing from the essential characteristics of the present invention. Therefore, the scope of the present invention is not limited to the above-described embodiments, it should be interpreted to include various embodiments within the scope equivalent to the contents described in the claims.

100: smart contract system
110: node
120: application or server
130: Blockchain
111: Merchant node
112: buyer node
10: Blockchain network

Claims (15)

The seller node registering the sale on the blockchain;
In a state in which a professional member node participates, the seller node negotiates the content of the contract with the buyer node to create an electronic contract, and verifies the legal validity of the created electronic contract;
Verifying the smart contract code corresponding to the electronic contract by the seller node;
The seller node extracting personal information and sensitive information from the electronic contract and de-identifying and encrypting the extracted personal information and sensitive information;
Storing, by the seller node, an electronic contract in which personal information and sensitive information are de-identified and encrypted in a distributed data storage; And
The seller node registering the electronic contract on a blockchain; Including,
The step of verifying the legal validity,
The seller node opening a side channel at the request of the buyer node;
Negotiating the contract contents with the buyer node through the side channel by the seller node participating in the specialized member node;
The seller node terminating the open side channel when negotiation of the contract is completed;
Storing, by the seller node, conversations occurring on the side channel in a distributed data storage; And
The seller node generating an electronic contract and verifying the legal validity of the generated electronic contract; Containing,
Smart contract method. According to claim 1,
The professional member node,
A node for legal advice on the above contract,
Smart contract method. delete According to claim 1,
The side channel,
Ethereum's status channel,
Smart contract method. According to claim 1,
The opening and closing of the side channel,
Through the private key signature of the seller node and the buyer node,
Smart contract method. According to claim 1,
The step of verifying the smart contract code,
The seller node performs at least one of a cross-compatibility check, execution code verification, and transaction validation, so that an error in the code does not occur when the smart contract code is executed,
Smart contract method. According to claim 1,
If the seller node encounters an error as a result of verifying the smart contract code, calling a controller node to resolve the error; Further comprising,
Smart contract method. The method of claim 7,
The controller node,
A node that mediates and audits transactions and detects abnormalities on the blockchain network to normalize transactions,
Smart contract method. According to claim 1,
The step of de-identification and encryption,
The seller node notifying the information subject of the presence or absence of the personal information and the sensitive information, and receiving consent from the information subject to use the information; Further comprising,
Smart contract method. According to claim 1,
The step of de-identification and encryption,
Setting, by the seller node, an effective period for information use according to an instruction of an information subject to the encrypted and de-identified information; Further comprising,
Smart contract method. According to claim 1,
Assigning a role to each node constituting the blockchain network through an application or a server; Further comprising,
Smart contract method. The method of claim 11,
Step of granting the role,
Granting a role of a normal user node to a node that has performed primary authentication;
Assigning a role of one of a seller node, a buyer node, a professional member node, or a controller node to the node that has performed the second authentication after the first authentication; Further comprising,
Smart contract method. The method of claim 12,
The first authentication is to register the wallet address,
The second authentication is to authenticate the real name,
Smart contract method. The method of claim 12,
The first authentication is to sign up for an application or server,
The second authentication is to register the wallet address and authenticate the real name,
Smart contract method. The method of claim 11,
The authority for each role is implemented as one smart contract,
Smart contract method.

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