KR20220079751A - Smart Contract System Using External Storage Based on Blockchain And Method Therefor - Google Patents

Abstract

According to one aspect of the present disclosure, in order to provide a transaction object of a smart contract to a purchaser, off-chain data is stored in an external storage linked with a block chain network. We provide a smart contract method and system that provides a transaction target to a buyer by encrypting and storing the encrypted data step by step and decrypting the encrypted data step by step using on-chain data.

Description

Smart Contract System Using External Storage Based on Blockchain And Method Therefor

The present invention relates to a smart contract system and method using external storage.

The content described in this section merely provides background information for the present embodiment and does not constitute the prior art.

In a conventional centralized network environment, the intervention of a trusted third party is required in a transaction of a resource. However, in a centralized network environment, there are problems such as that the transaction takes time and money, the reliability of a third party cannot be guaranteed, and the transaction cannot be led by the parties to the resource transaction.

Accordingly, blockchain technology, a decentralized system, was introduced. However, with the current block chain technology, one party who has either a transaction resource on the network, that is, a transaction object or a transaction consideration, is a transaction target. Alternatively, if the transaction consideration is pre-registered in the blockchain network, there is a possibility that the party who pre-registers may suffer loss in the transaction. Here, the pre-registration means that either one of the transaction object or the transaction price is registered in the smart contract with priority over the other. For example, if a transaction target is pre-registered in the block chain network in a situation where the transaction party cannot know whether a transaction is established, the confidentiality of data about the transaction target may be damaged. In addition, when large data is registered in the blockchain network, the speed of the network is lowered, and there is inefficiency in that all nodes in the network must register large data in the ledger.

In order to solve such performance degradation and inefficiency problems, on-chain data that stores and manages transaction-related data in the blockchain network and external storage linked to the blockchain network are stored and managed. A method of storing and managing data by classifying it as off-chain data has been proposed. However, in the case of linking the block chain network and external storage, there is a problem of being exposed to hacking or illegal copying of data as in the conventional centralized network environment.

Therefore, it is necessary to devise a transaction system that can prevent the loss of the party who pre-registered the resource and the degradation and inefficiency of the block chain network in the transaction of the resource.

According to one aspect of the present disclosure, in order to provide a transaction object of a smart contract to a purchaser, off-chain data is stored in an external storage linked with a block chain network. The main purpose is to provide a smart contract method and system that provides a transaction target to a buyer by encrypting and storing the encrypted data step by step and decrypting the encrypted data step by step using on-chain data.

According to one aspect of the present disclosure, in a smart contract method using external storage, the process of receiving a secret key and the transaction target from one node of a block chain network; According to a preset order, n hash codes (n is a natural number greater than or equal to 2) are generated based on the secret key, the transaction target is divided into n pieces of data, and the divided data is divided into the reverse order of the preset order. Encrypting based on the hash code and storing the n number of external storage (external storage) each; and registering a root code, which is a hash code last generated according to the preset order among the hash codes, and the secret key in a distributed ledger of the blockchain network. It provides a smart contract method, characterized in that

According to another aspect of the present disclosure, in the above-described transaction object providing method, the storing in each of the external storages includes generating first to n-th hash codes according to the preset order, but based on the secret key generating the first hash code, and generating the second to n-th hash codes based on a hash code having an index smaller than that of each hash code by one; and dividing the transaction target into first to n-th data according to the preset order, and encrypting the divided data in the reverse order of the preset order based on a hash code corresponding to each index, and n-th to n-th data There is provided a smart contract method comprising the steps of sequentially generating a first encrypted value, and sequentially storing the generated encrypted value in nth to first external storage, respectively.

According to another aspect of the present disclosure, in the above-described transaction object providing method, the process of acquiring the transaction object includes a first position value and a first value from the position modulation value and the encryption key modulation value using the secret key. A process of obtaining each encryption key; and decrypting the n-th to first encryption values based on the obtained first position value and the obtained first encryption key according to the preset order, and performing integrity verification for each decryption to verify the integrity of the transaction target. It provides a smart contract method comprising the process of acquiring

According to another aspect of the present disclosure, in the above-described transaction object providing method, the integrity of the entire transaction is verified based on the root code and the obtained n-th hash code, and the obtained n-th hash code is applied to the block. It provides a smart contract method, characterized in that it further comprises the process of adding to the distributed ledger of the chain network.

According to one aspect of the present disclosure, in providing a transaction target for a smart contract, the transaction target is encrypted step-by-step in an external storage linked with the blockchain network and distributed and stored, and encrypted data based on on-chain data is stored step by step By providing a method of providing a transaction target that enables the acquisition of a transaction object by decrypting it with / or has the effect of preventing tampering.

According to another aspect of the present disclosure, by registering the last decrypted data in the blockchain network, the integrity of the entire transaction can be verified, and there is an effect of non-repudiation of the transaction party or a third party.

Accordingly, when the method for providing a transaction target according to various aspects of the present disclosure is used, there is an effect of safely transacting large-capacity content between third parties who do not trust each other without degrading network performance.

1 is a conceptual diagram illustrating a smart contract system using external storage according to an embodiment of the present disclosure.
2 is a flowchart illustrating a smart contract method according to an embodiment of the present disclosure.
3 is an exemplary diagram of a method of storing divided and encrypted data in an external storage according to an embodiment of the present disclosure.
4 is an exemplary diagram illustrating an encryption process according to an embodiment of the present disclosure.
5 is an exemplary diagram illustrating a decoding process according to an embodiment of the present disclosure.

Hereinafter, some embodiments of the present disclosure will be described in detail with reference to exemplary drawings. It should be noted that, in adding the reference numerals to the components of each drawing, the same components are to have the same reference numerals as much as possible even if they are displayed on different drawings. In addition, in describing the present disclosure, if it is determined that a detailed description of a related known configuration or function may obscure the gist of the present disclosure, the detailed description thereof will be omitted.

In addition, in describing the components of the present disclosure, terms such as second and first may be used. These terms are only for distinguishing the elements from other elements, and the essence, order, or order of the elements are not limited by the terms. Throughout the specification, when a part 'includes' or 'includes' a certain element, this means that other elements may be further included, rather than excluding other elements, unless otherwise stated. . In addition, the '... Terms such as 'unit' and 'module' mean a unit that processes at least one function or operation, which may be implemented as hardware or software or a combination of hardware and software.

DETAILED DESCRIPTION The detailed description set forth below in conjunction with the appended drawings is intended to describe exemplary embodiments of the present disclosure and is not intended to represent the only embodiments in which the present disclosure may be practiced.

The present disclosure is a smart contract method using external storage, storing a transaction object in the external storage, and after the smart contract is established, the transaction object stored in the external storage to the buyer Describe how to provide In the present disclosure, on-chain data, which is data stored in a distributed ledger of a blockchain network, and off-chain data, which is stored in external storage, are distinguished. Through this, the disadvantage caused by the seller's pre-registration of the transaction target is prevented, and the spread of the distributed ledger due to the data size of the transaction target and the slowdown of the block chain network are prevented.

1 is a conceptual diagram illustrating a smart contract system using external storage according to an embodiment of the present disclosure.

In the present disclosure, a seller provides a secret key as on-chain data, and provides a transaction target as off-chain data. Here, the transaction target may be content, for example, pictures, videos, software, music, etc., but is not limited thereto, and transactions in the market such as bonds with warrants It can be anything that can be. The smart contract system divides the transaction target, encrypts each divided transaction target sequentially, and stores them in an external storage. A transaction is established by registering the transaction consideration that the buyer can fulfill the transaction conditions of the smart contract in the distributed ledger of the blockchain network, specifically, the database of the smart contract. Such transaction consideration may be money, coins, stock, content, etc., but is not limited thereto and may be any consideration that can be provided in exchange for a transaction in the market. Execution of the contract is performed by generating information, such as a transaction, used by the blockchain network to decrypt data distributed and stored in external storage, and delivering a secret key to the purchaser. The implementation of this contract can be completed by verifying the data integrity of the data decrypted by the buyer and adding the verification result to the distributed ledger of the blockchain network. In addition to these verification results, the effect of non-repudiation occurs in the transaction by this smart contract system.

Referring to FIG. 1 , a seller (or a seller node of a blockchain network, hereinafter omitted) generates a transaction related to a transaction proposal and registers it in the blockchain network, and all nodes in the blockchain network send the transaction proposal. make it viewable. In this case, the transaction proposal may include information on conditions for establishing a transaction and a transaction target. The seller further registers the secret key in the blockchain network to be transmitted to the buyer (or the buyer node of the blockchain network, hereinafter omitted) that satisfies the conditions of the smart contract. The secret key is a key capable of decrypting the location where the transaction object is stored and the encrypted transaction object, and the secret key is preferably an encrypted key based on the public key of the purchaser.

The seller uploads the transaction object to the external storage. At this time, the transaction target is divided, encrypted based on the secret key, and distributed and stored in physically or logically divided external storage. Due to distributed storage, it is possible to prevent problems such as data hacking or illegal copying that may occur when a transaction object is uploaded to an external storage.

The blockchain network is the information used to encrypt and distributedly store the transaction object in external storage, the storage location of the transaction object, the encryption key that can decrypt the transaction object, and/or the root code for verifying the integrity of the transaction. ), etc. are further registered in the distributed ledger so that the performance of the contract is performed. Here, it is preferable that the root code is a code that can ensure the data integrity of the decrypted transaction object when decrypting the transaction object during the transaction execution process. A specific example of the root code will be described later with reference to FIG. 3 .

When a transaction is established by satisfying the transaction conditions such as registering the transaction price in the block chain network, the buyer receives the secret key, the storage location of the transaction target, and/or the encryption key that can decrypt the transaction target from the block chain network. The encrypted transaction object is downloaded from the external storage, and the encrypted transaction object is decrypted to obtain the transaction object. Here, the method of receiving the secret key from the block chain network is, for example, a method in which the block chain network generates a transaction for the secret key of the smart contract, and the purchaser node calls a function to obtain the secret key from the smart contract. However, the present invention is not limited thereto and may be performed in a manner obvious to those skilled in the art. At this time, since the data integrity of the decrypted transaction target must be guaranteed, the purchaser can additionally receive the root code to verify the integrity of the entire transaction. Alternatively, by registering the information generated as a result of decryption in the blockchain network, all nodes in the blockchain network share the integrity of the transaction.

2 is a flowchart illustrating a smart contract method according to an embodiment of the present disclosure.

In FIG. 1, when the seller registers a transaction proposal, an embodiment in which a smart contract is established by the buyer satisfying the transaction conditions of the proposal has been described. It can be established by satisfying the transaction conditions, but is not limited thereto.

The buyer requests a service by generating a transaction on the blockchain network (S200).

The seller who wants to provide the service requested by the buyer generates a transaction and registers the transaction proposal for the provision of the transaction object in the block chain network (S202).

The buyer inquires one or more registered transaction proposals and registers the transaction price suggested by a specific purchaser in the blockchain network (S204). At this time, the registered transaction price may be a part of the total transaction price as a deposit, and after the buyer obtains the transaction price with data integrity verified, the remaining transaction price can be registered in the blockchain network to be paid to the seller. As such, it is self-evident that the specific transaction method that provides the transaction target and transaction consideration varies depending on the contents of the smart contract.

The seller who has requested the transaction uploads the transaction object to the external storage (S206) and registers the secret key used for encryption of the transaction object in the block chain network (S208). The private key is preferably a key encrypted by a public key provided by the purchaser, and the purchaser can decrypt the private key using a private key corresponding to his or her public key. The seller can verify the information (such as the storage location of Fig. 2) that can know the location of the transaction object stored in a distributed manner, information that can decrypt the transaction object stored in the distribution (such as the encryption key in Fig. 2) and/or the integrity of the entire transaction. Possible information (such as the root code in FIG. 2) is further registered in the block chain network (S208).

The seller divides and encrypts the uploaded transaction object based on the secret key, the root code, the storage location of the transaction object, the encryption key, and the like, and distributes and stores the uploaded transaction object in external storage (S210).

Here, the precedence of steps S208 and S210 may be changed, and steps S206 to S210 may be performed in parallel.

If the transaction consideration registered in step S204 satisfies the transaction conditions of the transaction proposal, a smart contract is established (S214). The establishment of such a smart contract is preferably made after all steps S200 to S212 are performed, but it is self-evident that some steps can be created, changed, or omitted.

According to the establishment of the smart contract, the blockchain network delivers the secret key, the storage location of the transaction object (or an address value that can refer to the transaction object, etc.) and/or the encryption key to the purchaser (S216). This transfer can be performed by generating a transaction containing the private key, the storage location of the transaction target and/or the encryption key to the purchaser node.

The purchaser downloads the transaction object from the external storage using the received storage location, encryption key and/or secret key (S218), and decrypts the downloaded transaction object (S220).

The buyer additionally receives the root code from the block chain network (S222), finally verifies the data integrity of the decrypted transaction target (S224), and registers the verification result in the block chain network (S226).

When it is successfully verified and the contract execution of the smart contract is completed (S228), the blockchain network pays the transaction price to the seller (S230). As a result of the verification, if data integrity is not recognized, the blockchain network may not pay the transaction price to the seller, pay only a portion, or request the seller to re-upload the transaction object, but this is an example and In this case, it is preferable to process according to the method preset in the smart contract system or the contract between the seller and the buyer.

In step S228, it is preferable that the confirmation of the completion of the smart contract is performed in consideration of the transaction target and whether the transaction price conforms to the contract contents in light of the contents of the smart contract. For example, the quality of the transaction object provided by the seller, whether forgery/falsification of the transaction price provided by the buyer, etc. may be further considered.

2 illustrates that each process is sequentially executed, this is merely illustrative of the technical idea of an embodiment of the present disclosure. In other words, one of ordinary skill in the art to which an embodiment of the present disclosure pertains may change the order described in FIG. Since it may be applied by various modifications and variations to be executed in parallel, it is not limited to the time series sequence of FIG. 2 .

3 is an exemplary diagram of a method of storing divided and encrypted data in an external storage according to an embodiment of the present disclosure.

Referring to FIG. 3, the smart contract system divides the transaction target according to a preset order (eg, data arrangement order), encrypts it in the reverse order of the divided order, and decrypts it again in the reverse order of the encrypted order, that is, the preset order. Data confidentiality can be guaranteed.

The smart contract system (or external storage, hereinafter omitted) divides the transaction target into n pieces of data (n is a natural number greater than or equal to 2), that is, first data to n-th data according to a preset order. The smart contract system uses n encryption keys corresponding to each index of the divided data, that is, the first encryption key to the nth encryption key, in order to encrypt each divided data using each encryption key. create That is, the first encryption key is used to encrypt the first data. In this case, in order to generate n encryption keys differently, an ECC (Elliptic Curve Cryptography)-based child key generation algorithm, etc. may be used.

This encryption key is used again in the process of decrypting the encrypted data, but unlike in the encryption process, the encrypted value of an index that is one less than itself must be decrypted before decryption can proceed to obtain the encryption key of the next index. . For example, each encryption value may include an encryption key of an index 1 larger than itself, and in this case, the n th encryption value is an encryption key of an index 1 larger than itself because there is no encryption key of an index larger than itself. It may be configured not to include.

The smart contract system encrypts each divided data in the reverse order of the preset order, that is, the index of the divided data is in descending order, and distributes and stores the encrypted data in each location of the external storage. Specifically, the smart contract system generates an n-th encryption value by encrypting n-th data using an n-th encryption key, and distributes and stores the n-th encryption value to obtain an n-th position value that can refer to the n-th encryption value. acquire After that, after encrypting the (n-1)th data using the (n-1)th encryption key (generating the (n-1)th encryption value), the (n-1)th position value is Save the password value. This process continues until the first encryption value is stored in the external storage.

Here, the external storage may be a distributed hash table, and accordingly, the first to n-th position values may be hash keys for referencing each node of the distributed hash table.

This position value is used again in the process of decrypting the encrypted data, but unlike in the encryption process, the encryption value of the previous index must be decrypted before decryption is performed so that the position value of the next index can be obtained. For example, each cryptographic value may further include the encrypted position value of the index 1 larger than itself, and in this case, since the nth cryptographic value does not have a position value of the index 1 larger than itself, the position value of the index 1 larger than itself is included. It may be configured not to include.

4 is an exemplary diagram illustrating an encryption process according to an embodiment of the present disclosure.

The encryption process according to an embodiment of the present disclosure is performed to verify the data integrity of the decrypted data in each subsequent decryption step. The n pieces of divided data are encrypted in descending order of the index, and each encrypted data is encrypted using the data used in the encryption process of the previously encrypted data, that is, data whose index is 1 larger than itself. The smart contract system further uses a hash code in the encryption process to verify the integrity of the data when decrypting the encrypted data. This hash code is composed of a first hash code to an n-th hash code to correspond to each index of the divided data, the first hash code is generated using a secret key, and the second to n-th hash code is generated just before It is generated based on the hash code.

Referring to FIG. 4 , the smart contract system generates a first hash code by inputting the first data and the secret key as input values of a preset function (eg, a hash function) in the order of increasing index of each divided data. . Thereafter, the second hash code is generated by inputting the second data and the first hash code as input values of a preset function. The smart contract system increments the index of each data by 1 and repeats the above-described procedure to generate a first hash code to an n-th hash code. At this time, the n-th hash code is a code for verifying the integrity of the entire transaction, and becomes the root code and is registered in the blockchain network.

The smart contract system obtains the nth to first encryption values obtained by encrypting each divided data in the reverse order of the order in which the transaction target is divided, that is, the index of the divided data decreases by 1, and stores the obtained encryption value in the external storage. distributed storage. The smart contract system obtains the n-th encryption value by encrypting the n-th data and the root code using the n-th encryption key. The obtained n-th encryption value is stored in an external storage location that can be inquired as an n-th location value. Thereafter, the smart contract system encrypts the (n-1)th data, the (n-1)th hash code, the nth position value, and the nth encryption key using the (n-1)th encryption key, thereby 1) Obtain an encryption value. The smart contract system decrements the index of each data by 1, repeats the above-described procedure, generates an nth cryptographic value to a first cryptographic value, and obtains a first location value.

The smart contract system generates an encoded location reference by performing a hexadecimal operation (eg, arithmetic and logic calculation) on the first location value and the secret key, and sets the first encryption key and the secret key to 16 Generates an encoded encrypt key by performing a hexadecimal operation. These position modulation values and encryption key modulation values are added to the distributed ledger of the blockchain network, respectively, and transmitted to the node of the purchaser where the smart contract is established.

5 is an exemplary diagram illustrating a decoding process according to an embodiment of the present disclosure.

FIG. 5 shows an example of decrypting data encrypted and distributed according to FIG. 4 .

In the decryption process according to an embodiment of the present disclosure, the process of decrypting the encrypted data verifies the data integrity of the decrypted data in each step of decryption, and if the data integrity is not verified in any step, the integrity of the entire transaction is verified. performed so that it cannot be The n encrypted values are decrypted in the ascending order of the index, and each decrypted data is decrypted using the data obtained in the process of decrypting the immediately decrypted data, that is, data having an index smaller than itself by one. The data obtained during the decryption process is a location value that can refer to the next encryption value to be decrypted and a hash code used for decryption.

Referring to FIG. 5, the smart contract system transmits the secret key, the location modulation value, and the encryption key modulation value to the purchaser's node, and the purchaser node performs an inverse operation based on the secret key to perform an inverse operation on the location modulation value and the encryption key modulation value. A first position value and a first encryption key are obtained from each.

The purchaser node acquires and decrypts each encryption value from the external storage in the reverse order of the encryption order of the encryption value, that is, the index of the encryption value increases by 1. The purchaser node obtains the first encryption value using the first location value, and decrypts the first encryption value using the first encryption key to obtain the first data, the first hash code, the second location value, and the second encryption key. to acquire Thereafter, the buyer node increments the index by 1 and repeats the above-described procedure to generate the first data to the n-th data to obtain the entire transaction target.

On the other hand, when data is decrypted through only the above-described procedure, there is a problem in that it cannot be guaranteed whether the data decrypted by the buyer node matches the transaction price uploaded by the seller (seller node). Accordingly, it is preferable to further perform a process of verifying the integrity of the data based on the decrypted data for each procedure described above.

Referring to FIG. 5 , the purchaser node verifies the data integrity of the decrypted data using the first data and the first hash code. Specifically, the purchaser node inputs the first data obtained by decrypting the first encryption value and the received secret key as the input value of the preset function used to generate the first hash code, and the generated value is the first password. Data integrity is verified by determining whether the value matches the first hash code obtained by decrypting it. Thereafter, the purchaser node inputs the second data and the first hash code obtained by decrypting the second encryption value as an input value of a preset function, and the value generated by decrypting the second encryption value is obtained by decrypting the second hash code and Data integrity is verified by determining whether they match. The purchaser node increments the index by 1 and performs the aforementioned integrity verification procedure for each decryption process. After the nth data integrity verification procedure is performed, the purchaser node receives the nth hash code obtained by decrypting the nth encryption value and the root code received from the blockchain network (or inquiring the distributed ledger), that is, the decrypted root code. It is possible to verify the integrity of the entire transaction by further determining whether it is a match or not. At this time, if any one integrity verification procedure fails in the decryption process, the integrity verification of the root hash is not performed. Therefore, the integrity verification of the root hash means verifying the integrity of the entire transaction.

Another embodiment of verifying the integrity of the entire transaction is to register the decrypted root code in the blockchain network. As a result, all nodes in the blockchain network share information about the integrity of the entire transaction, which has the effect of preventing one party or a third party from denying the transaction in the future.

Various implementations of storage, networks, processes, steps, etc. described in the specification may include digital electronic circuits, integrated circuits, field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), computer hardware, It may be implemented in firmware, software, and/or a combination thereof. These various implementations may include being implemented in one or more computer programs executable on a programmable system. The programmable system includes at least one programmable processor (which may be a special purpose processor) coupled to receive data and instructions from, and transmit data and instructions to, a storage system, at least one input device, and at least one output device. or may be a general-purpose processor). Computer programs (also known as programs, software, software applications or code) contain instructions for a programmable processor and are stored on a "computer-readable recording medium".

The computer-readable recording medium includes all types of recording devices in which data readable by a computer system is stored. These computer-readable recording media are non-volatile or non-transitory, such as ROM, CD-ROM, magnetic tape, floppy disk, memory card, hard disk, magneto-optical disk, and storage device. It may further include a medium or a transitory medium such as a data transmission medium. In addition, the computer-readable recording medium may be distributed in network-connected computer systems, and computer-readable codes may be stored and executed in a distributed manner.

Various implementations of the systems and techniques described herein may be implemented by a programmable computer. Here, the computer includes a programmable processor, a data storage system (including volatile memory, non-volatile memory, or other types of storage systems or combinations thereof), and at least one communication interface. For example, the programmable computer may be one of a server, a network appliance, a set-top box, an embedded device, a computer expansion module, a personal computer, a laptop, a Personal Data Assistant (PDA), a cloud computing system, or a mobile device.

The above description is merely illustrative of the technical idea of this embodiment, and a person skilled in the art to which this embodiment belongs may make various modifications and variations without departing from the essential characteristics of the present embodiment. Accordingly, the present embodiments are intended to explain rather than limit the technical spirit of the present embodiment, and the scope of the technical spirit of the present embodiment is not limited by these embodiments. The protection scope of this embodiment should be interpreted by the following claims, and all technical ideas within the scope equivalent thereto should be interpreted as being included in the scope of the present embodiment.

Claims (16)

In a smart contract method using external storage,
A process of receiving a secret key and the transaction target from one node of the block chain network;
According to a preset order, n hash codes (n is a natural number greater than or equal to 2) are generated based on the secret key, the transaction target is divided into n pieces of data, and the divided data is divided into the reverse order of the preset order. Encrypting based on the hash code and storing the n number of external storage (external storage) each; and
A process of registering a root code, which is a hash code last generated according to the preset order among the hash codes, and the secret key in a distributed ledger of the blockchain network
A smart contract method comprising a. According to claim 1,
The root code is the last divided data according to the reverse order of the preset order among the divided data and the hash code generated second from the last according to the preset order among the hash codes as an input value of a preset function. A smart contract method, characterized in that it is obtained by inputting it. According to claim 1,
The process of storing in each of the external storage is,
First to n-th hash codes are generated according to the preset order, the first hash codes are generated based on the secret key, and the second to n-th hash codes are generated based on a hash code having an index 1 smaller than each hash code. The process of generating n hash codes; and
The transaction target is divided into first to n-th data according to the preset order, and the divided data is encrypted in the reverse order of the preset order based on a hash code corresponding to each index to n-th to n-th data. 1 A process of sequentially generating an encrypted value, and sequentially storing the generated encrypted value in n-th to first external storage, respectively
A smart contract method comprising a. 4. The method of claim 3,
The first hash code is obtained by inputting the first data and the secret key as input values of a preset function,
The second to nth hash codes are obtained by inputting divided data corresponding to each index and a hash code having an index smaller than that of each hash code by one as an input value of the preset function. 4. The method of claim 3,
The process of storing each in the external storage is,
Further using the first to nth encryption keys (encrypt key), the nth to nth data by encrypting the first to nth data using an encryption key corresponding to each index together with a hash code corresponding to each index 1 A smart contract method characterized by generating a cryptographic value. 6. The method of claim 5,
In the n-th to the first position value that is each position value for referring to the n-th to the first encryption value in the n-th to the first external storage, the (n-1) to the first encryption value is each A smart contract method, characterized in that it is generated by further encrypting a position value having an index 1 greater than the cryptographic value. 7. The method of claim 6,
The n-th to the first external storage is each node constituting a distributed hash table, respectively,
The n-th to the first location value is a hash key for referencing each node of the distributed hash table in which the n-th to the first cryptographic value is stored. 7. The method of claim 6,
The process of registering in the distributed ledger of the blockchain network is,
A smart contract method, characterized in that the first location value and the first encryption key are further registered in the distributed ledger of the block chain network. 9. The method of claim 8,
The registration of the first position value and the first encryption key,
The position modulation value generated by hexadecimal operation of the first position value and the secret key and the encryption key modulation value generated by hexadecimal operation of the first encryption key and the secret key are further added to the distributed ledger of the blockchain network A smart contract method, characterized in that it is performed by registering. 10. The method of claim 9,
When one node of the block chain network achieves the transaction condition of the smart contract, the process of transferring the secret key, the location modulation value, and the encryption key modulation value to the node that has achieved the transaction condition
A smart contract method further comprising a. 11. The method of claim 10,
A process of obtaining the transaction target by decrypting the n-th to the first encryption value according to the preset order by using the position modulation value and the encryption key modulation value
A smart contract method further comprising a. 12. The method of claim 11,
The process of acquiring the transaction target is
obtaining a first position value and a first encryption key from the position modulation value and the encryption key modulation value using the secret key, respectively; and
Based on the obtained first position value and the obtained first encryption key, the nth to first encryption values are decrypted according to the preset order, and integrity verification is performed for each decryption to obtain a transaction target whose integrity is verified. process of obtaining
A smart contract method comprising a. 13. The method of claim 12,
The process of acquiring the transaction target for which the integrity has been verified,
A first encryption value is obtained using the obtained first location value, and the obtained first encryption value is decrypted using the obtained first encryption key to obtain first data, a first hash code, and a second location value. and obtaining a second encryption key, inputting the obtained first data and the secret key as an input value of the preset function, and comparing the obtained first hash code with a value generated to verify the integrity of the first data A smart contract method characterized in that it is performed. 14. The method of claim 13,
The process of acquiring the transaction target for which the integrity has been verified,
With respect to the ith position value (1< i < n, i is a natural number), the ith encryption key, and the ith encryption value, the ith encryption value obtained using the ith position value is obtained, and the ith encryption value is obtained. The i-th encryption value is decrypted using the key to obtain the i-th data, the i-th hash code, the (i+1)-th position value, and the (i+1)-th encryption key, and the obtained i-th data and the obtained A smart contract method, characterized in that integrity verification is performed by comparing an i-th hash code obtained by inputting a (i-1)-th hash code as an input value of the preset function and a value generated. 15. The method of claim 14,
The process of acquiring the transaction target for which the integrity has been verified,
The n-th encryption value is obtained by using the obtained n-th position value, and the obtained n-th encryption value is decrypted using the obtained n-th encryption key to obtain n-th data and an n-th hash code. A smart contract method, characterized in that integrity verification is performed by comparing the value generated by inputting the n-th data and the obtained (n-1)-th hash code as an input value of the preset function with the obtained n-th hash code . 15. The method of claim 14,
The process of verifying the integrity of the entire transaction based on the root code and the obtained n-th hash code, and adding the obtained n-th hash code to the distributed ledger of the blockchain network
A smart contract method further comprising a.

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