KR102311354B1 - Blockchain transaction method with reduced transaction size using cryptographic hash algorithm - Google Patents

Abstract

The present invention relates to a blockchain transaction method in which a transaction size is reduced using a cryptographic hash algorithm, and more particularly, to a transaction method in a blockchain-based system including a plurality of blockchain nodes, a hash value of a recipient public key, It is characterized in its configuration to generate and propagate a transaction composed of the hash value and amount of the sender's signature.
In addition, the present invention relates to a blockchain transaction method in which a transaction size is reduced by using a cryptographic hash algorithm, and more particularly, as a transaction method in a blockchain-based system including a plurality of blockchain nodes, the blockchain comprising: A fixed block in which all transactions included in a block are in a stable state and an unfixed block including at least one unstable transaction, (a) a hash of the recipient's public key generating a transaction comprising a value, a hash value of the sender's signature, and an amount; (b) for verification in the non-fixed block, storing transaction information with a sender public key and sender signature in an unauthorized transaction pool, and propagating the transaction; and (c) if the block containing the transaction is included in the fixed block, removing the transaction information from the unauthorized transaction pool.
According to the blockchain transaction method in which the transaction size is reduced by using the cryptographic hash algorithm proposed in the present invention, by generating and propagating a transaction consisting of the hash value of the recipient public key, the hash value of the sender's signature, and the amount, By significantly reducing the transaction size with the public key and signature size, various quantum-resistant digital signatures can be introduced into the blockchain, ultimately increasing the quantum-resistant digital signature compatibility of the blockchain and reducing the overall blockchain size. have.

Description

A blockchain transaction method that reduces the transaction size using a cryptographic hash algorithm {BLOCKCHAIN TRANSACTION METHOD WITH REDUCED TRANSACTION SIZE USING CRYPTOGRAPHIC HASH ALGORITHM}

The present invention relates to a blockchain transaction method, and more particularly, to a blockchain transaction method in which a transaction size is reduced using a cryptographic hash algorithm.

Digital signature schemes based on asymmetric encryption algorithms such as RSA and ECC are usually used for digital signatures. However, when a practically usable quantum computer is implemented, the performance of the processor can be greatly improved. can solve The Shore algorithm can compute the factorization and discrete log problems, which are the basis of public key encryption algorithms, within polynomial time, making RSA and ECC weak encryption algorithms. The Grover algorithm can halve the security complexity of existing cryptographic algorithms, so the security of cryptographic algorithms such as hash functions and symmetric keys is halved.

Most distributed ledgers and blockchains use ECC-based Electronic Signature Scheme (ECDSA). Distributed ledgers and blockchains that use them cannot be expected to be of long-term use when considering quantum computers. In preparation for this, research is underway to introduce Post-Quantum Cryptography into the block chain. The combination of quantum-resistant cryptography and blockchain is called Post-Quantum Blockchain, and is resistant to attacks on quantum algorithms such as Shore algorithm and Grover algorithm.

However, if an arbitrary quantum-resistant cipher is introduced into the blockchain as it is to implement a quantum-resistant blockchain, a problem with the bloated public key and signature size may become a problem, or the signature verification time may become longer. Therefore, there is a need to develop a technology that can solve this problem.

On the other hand, as prior art related to the present invention, Patent Registration No. 10-1950912 (title of the invention: blockchain-based transaction verification system and method thereof, registration date: February 15, 2019) has been disclosed.

The present invention has been proposed to solve the above problems of the previously proposed methods, and by generating and propagating a transaction consisting of a hash value of a recipient public key, a hash value of a sender's signature, and an amount of money, By significantly reducing the transaction size with the signature size, various quantum-resistant digital signatures can be introduced into the blockchain, ultimately increasing the quantum-resistant digital signature compatibility of the blockchain and reducing the overall blockchain size. The purpose of this is to provide a blockchain transaction method that reduces the transaction size by using a mathematical hash algorithm.

A blockchain transaction method in which the transaction size is reduced by using a cryptographic hash algorithm according to a feature of the present invention to achieve the above object,

A transaction method in a blockchain-based system including a plurality of blockchain nodes, comprising:

It is characterized in that it generates and propagates a transaction composed of the hash value of the recipient's public key and the hash value of the sender's signature.

Preferably,

(1) storing the hash value of the recipient public key in transaction data;

(2) calling the signature function;

(3) signing the hash value of the previous transaction and the recipient public key with the sender private key; and

(4) generating a hash value of the sender's signature of step (3) and storing it in the transaction data,

It is possible to create a transaction composed of the hash value of the recipient's public key and the hash value of the sender's signature.

Preferably,

The blockchain uses monetary assets to convert values into amounts and transacts,

Generate and propagate a transaction consisting of the hash value of the recipient's public key, the hash value of the sender's signature, and the amount,

(1) storing the hash value and amount of the recipient public key in transaction data;

(2) calling the signature function;

(3) signing the hash value of the previous transaction, the recipient public key and the amount with the sender private key; and

(4) generating a hash value of the sender's signature of step (3) and storing it in the transaction data,

It is possible to generate a transaction composed of the hash value of the recipient's public key, the hash value of the sender's signature, and an amount.

More preferably, after step (4),

(5) The method may further include generating transaction information including the transaction data and additional information about the transaction.

Even more preferably,

The transaction information includes a sender public key and a sender signature,

The transaction information is stored in an unauthorized transaction pool, and when all transactions in blocks including transactions in the pool become stable, the transaction information may be removed from the unauthorized transaction pool.

Even more preferably, the transaction information includes:

It may further include the public key of the recipient for verification of the recipient and a hash value of the transaction.

Preferably, the blockchain comprises:

A fixed block in which all transactions included in the block are in a stable state and an unfixed block including at least one unstable transaction may be included.

More preferably,

For verification in the non-fixed block, a sender's public key and sender's signature are attached, and when the non-fixed block becomes a fixed block, the attached sender's public key and sender's signature can be removed from the transaction.

In addition, the block chain transaction method in which the transaction size is reduced by using a cryptographic hash algorithm according to the features of the present invention to achieve the above object,

A transaction method in a blockchain-based system including a plurality of blockchain nodes, comprising:

The block chain includes a fixed block in which all transactions included in the block are in a stable state and an unfixed block including at least one unstable transaction,

(a) generating a transaction consisting of a hash value of a recipient public key and a hash value of a sender's signature;

(b) for verification in the non-fixed block, storing transaction information with a sender public key and sender signature in an unauthorized transaction pool, and propagating the transaction; and

(c) when the block containing the transaction is included in the fixed block, removing the transaction information from the unauthorized transaction pool.

According to the blockchain transaction method in which the transaction size is reduced by using the cryptographic hash algorithm proposed in the present invention, by generating and propagating a transaction consisting of the hash value of the recipient public key, the hash value of the sender's signature, and the amount, By significantly reducing the transaction size with the public key and signature size, various quantum-resistant digital signatures can be introduced into the blockchain, ultimately increasing the quantum-resistant digital signature compatibility of the blockchain and reducing the overall blockchain size. have.

1 is a diagram showing the predicted average transaction size, block size, and overall size of the chain for a quantum-resistant digital signature scheme.
2 is a diagram illustrating an existing transaction structure;
3 is a diagram showing fixed blocks and non-fixed blocks in the main chain.
4 is a diagram illustrating a flow of a blockchain transaction method in which a transaction size is reduced using a cryptographic hash algorithm according to an embodiment of the present invention.
5 is a diagram illustrating a transaction structure according to a block chain transaction method in which a transaction size is reduced using a cryptographic hash algorithm according to an embodiment of the present invention.
6 is a diagram illustrating a detailed flow of step S100 in a block chain transaction method in which a transaction size is reduced using a cryptographic hash algorithm according to an embodiment of the present invention.
7 is a diagram illustrating an algorithm for the implementation of step S100 of the block chain transaction method in which the transaction size is reduced using a cryptographic hash algorithm according to an embodiment of the present invention.
8 is a diagram illustrating an algorithm for processing of step S300 in a block chain transaction method in which a transaction size is reduced using a cryptographic hash algorithm according to an embodiment of the present invention.
9 is a diagram illustrating an algorithm for verifying a fixed block in a blockchain transaction method in which a transaction size is reduced using a cryptographic hash algorithm according to an embodiment of the present invention.
10 is a view showing the average signature and verification time and standard deviation in each experimental environment.

Hereinafter, preferred embodiments will be described in detail so that those of ordinary skill in the art can easily practice the present invention with reference to the accompanying drawings. However, in describing a preferred embodiment of the present invention in detail, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted. In addition, the same reference numerals are used throughout the drawings for parts having similar functions and functions.

In addition, throughout the specification, when a part is connected to another part, this includes not only the case where it is directly connected, but also the case where it is indirectly connected with another element interposed therebetween. In addition, the inclusion of any component means that other components may be further included, rather than excluding other components, unless otherwise stated.

The present invention relates to a block chain transaction method in which the transaction size is reduced using a cryptographic hash algorithm, and the block chain transaction method in which the transaction size is reduced using a cryptographic hash algorithm according to a feature of the present invention, including a memory and a processor It may consist of software that is written in hardware. For example, the blockchain transaction method in which the transaction size is reduced by using the cryptographic hash algorithm of the present invention can be stored and implemented in a personal computer, a notebook computer, a server computer, a PDA, a smart phone, a tablet PC, and the like. Hereinafter, for convenience of description, a subject performing each step may be omitted.

In a blockchain-based system, a plurality of transactions can be gathered to form a block, and a block can be configured in the form of a block chain. A node can be implemented as a server or computer, and each node is equipped with a blockchain, which can be called a blockchain node. In a blockchain-based system including a plurality of blockchain nodes, a node creates a transaction according to an event such as a payment, each node receives and verifies transaction information, and propagates the transaction to the next designated nodes. .

Digital signature schemes based on asymmetric cryptographic algorithms such as RSA and ECC are usually used for digital signatures for transactions. However, as the practical implementation of quantum computers is imminent, research is underway to introduce Post-Quantum Cryptography into the blockchain.

All quantum-resistant cryptography has a larger public key size and signature size than ECDSA. A public key differs by a minimum of 2 times to a maximum of 64 times, and a signature differs by a minimum of 22 times and a maximum of 1920 times. If such a quantum-resistant digital signature is applied as it is, the size of the transaction will also increase proportionally, and the size of the block and blockchain will also increase proportionally. Therefore, as the blockchain storage space becomes very large, it is expected that the resources and costs borne by one node will be amplified.

1 is a diagram showing predictions of the average transaction size, block size, and overall size of the chain for a quantum-resistant digital signature scheme. 1 is based on the total size of the Bitcoin blockchain as of 09:00 (GMT+0900) on April 14, 2019, about 207.66 GB, the average number of transactions is 2,763, and the number of blocks is 578,151. It is an estimate of the average transaction size, block size, and overall size of the chain for the signature scheme. Assuming that the number of blocks equal to that of current Bitcoin is accumulated, as can be seen in FIG. 1, the size of the entire chain for the quantum-resistant digital signature scheme was estimated to be from a minimum of about 54Tb to a maximum of 1,924Tb. This increase in the size of the public key/signature pair will double the weight of the block chain and become a significant burden. Therefore, there is a need for a method to reduce the burden on the public key/signature size.

A block chain transaction method in which a transaction size is reduced using a cryptographic hash algorithm according to an embodiment of the present invention is a transaction method in a block chain-based system including a plurality of block chain nodes, the hash value of the recipient public key and the sender You can create and propagate a transaction that consists of a hash value of a signature. However, when the blockchain uses monetary assets to convert the value into an amount and transacts, a transaction consisting of the hash value of the recipient's public key, the hash value of the sender's signature, and the amount can be generated and propagated. That is, in the present invention, in the case of a block chain that does not exchange values according to the characteristics of the block chain, the transaction is composed of the hash value of the recipient's public key and the hash value of the sender's signature, and the value is obtained using monetary assets such as cryptocurrency In the case of a block chain that converts and transacts , it is possible to compose a transaction by including an amount in addition to the hash value of the recipient's public key and the hash value of the sender's signature.

Therefore, according to the block chain transaction method in which the transaction size is reduced by using the cryptographic hash algorithm proposed in the present invention, the hash value of the recipient public key, not the recipient public key, and the public key of the sender's signature other than the sender's signature are included. By using a cryptographic hash algorithm, the size of a transaction with a bloated public key and signature size can be significantly reduced. Therefore, various quantum-resistant digital signatures can be introduced into the blockchain, ultimately increasing the quantum-resistant digital signature compatibility of the blockchain and reducing the size of the overall blockchain.

Hereinafter, for convenience of explanation, a transaction structure including an amount is described as a basis, and in the case of a block chain that does not exchange value, the rest may be processed in the same way, except that the amount is excluded.

2 is a diagram illustrating an existing transaction structure. In the structure shown in FIG. 2, a transaction includes all information such as a sender's signature, sender's public key, receiver's public key, and amount. On the other hand, in the block chain transaction method in which the transaction size is reduced using a cryptographic hash algorithm according to an embodiment of the present invention, only the hash value of the recipient public key, the hash value of the sender's signature, and the amount are included using the cryptographic hash algorithm. By proposing a transaction structure that

Hereinafter, with reference to FIG. 2, concepts and symbols used for description in the present invention will be described.

Block: FIG. 2 is an example representing a block structure, and the present invention follows the following structure as a basic block structure.

Mainchain: The longest chain that nodes consider valid through consensus is called the mainchain.

Tip: The block at the end of the main chain is called a tip.

Transaction: A transaction is denoted by TX. In order to use a coin, the sender may call a transaction containing the previously received coin transfer history, and in this case, the called transaction is indicated as PrevTX.

Public key private key pair: In the _{present invention, pub s} and priv _s are expressed to indicate the sender's key pair, and the recipient's key pair is expressed as pub _r and priv _r .

Amount: The amount of coins the sender receives in a transaction is called amount.

Hash function: It is a function expression H(x)=h that performs a hash function, and maps a hash value h of a fixed bit length from an input x of an arbitrary finite bit length to an output. A hash function can be considered safe only if it satisfies three properties: (a) preimage resistance, (b) 2nd-preimage resistance, and (c) collision resistance.

Signature: Transactions usually include the sender's signature. In the present invention, the elements included in the sender's signature σ _s are abbreviated, and it can be made through the following Equation (1).

That is, the hash value H (PrevTX) of the previous transaction containing the reception details of the coin to be used is put in for reference, and the public key pub _{r of the} recipient and the amount amount are signed with _{the private key priv s of the sender.} From this, the signature σ _s can be derived.

Signature verification: Equation 2 below is a functional expression for verifying a signature. The signature σ can be validated using the node's public key pub.

When the node's public key pub and signature σ are verified, the verification value v is obtained, and the verification value 0 means true and 1 means false. That is, if v=0, the transaction is valid.

Security parameters: When a transaction is included in a block, the transaction is said to be confirmed. Also, if a block is added following a block including a transaction, the confirmation number increases by the number of blocks added. As the number of approvals increases, the probability of a transaction being manipulated decreases, and when the number of approvals is k or more, the status of a transaction can be expressed as stable. In this case, k is a security parameter. The number of approvals depends on the height of the block containing the transaction, and the security parameter k is a fixed constant, which can be set by the developer/operator.

In Equation 3, if the number of approvals of a transaction is less than k, the state of the transaction is unstable and is expressed as 1. When the number of approvals of a transaction is more than k, the state of the transaction is stable and is expressed as 0.

Fixed block / non-fixed block: When all TXs included in a block have a stable state, the block is called a fixed block. In other words, a fixed block is a block that is more than k blocks away from the tip of the main chain. Also, a block that is less than k from the tip of the main chain is called an unfixed block, and the TX included in the unfixed block is unstable.

3 is a diagram showing fixed blocks and non-fixed blocks in the main chain. As shown in FIG. 3 , the block chain includes at least one fixed block in which all transactions included in the block are in a stable state and at least one unstable block (unfixed block) may include.

Hereinafter, a detailed flow of a blockchain transaction method in which a transaction size is reduced using a cryptographic hash algorithm according to an embodiment of the present invention will be described in detail using the concept as described above.

4 is a diagram illustrating a flow of a blockchain transaction method in which a transaction size is reduced using a cryptographic hash algorithm according to an embodiment of the present invention. As shown in FIG. 4, the block chain transaction method in which the transaction size is reduced by using a cryptographic hash algorithm according to an embodiment of the present invention is a transaction consisting of a hash value of the recipient's public key and a hash value of the sender's signature. A step of generating (S100), for verification in a non-fixed block, storing the transaction information with the sender public key and the sender signature attached to the unauthorized transaction pool, and propagating the transaction (S200), and When the block is included in the fixed block, it may be implemented including the step (S300) of removing the transaction information from the unapproved transaction pool.

In step S100, it is possible to generate a transaction composed of the hash value of the receiver's public key and the hash value of the sender's signature. At this time, when the blockchain uses monetary assets to convert the value into an amount and transacts, a transaction consisting of the hash value of the recipient's public key, the hash value of the sender's signature, and the amount can be created. 5 is a diagram illustrating a transaction structure according to a block chain transaction method in which a transaction size is reduced using a cryptographic hash algorithm according to an embodiment of the present invention.

In the present invention, we propose a new transaction structure and consensus mechanism for applying quantum-resistant digital signatures. If the structure of the existing transaction is simplified, it consists of the sender's signature and public key pair, the receiver's public key, and the remittance amount. As shown in Fig. 2, the components of the existing transaction are largely divided into two types. There is the sender's signature σ _s (sigS in FIG. 2) and public key pub _s (pubS in FIG. 2) for proof of ownership of the amount to be used, and the recipient's public key pub _r (in FIG. 2) as information about the recipient of the amount pubR), the amount of the amount received is recorded. In this case, the signature is the hash value of the previous transaction, the public key of the recipient, and the value of signing the amount.

However, if quantum-resistant cryptography is applied to the existing structure as it is, the size of the transaction may be enlarged as described above. Accordingly, in the present invention, it is intended to reduce the size of the public key/signature by proposing a transaction consisting of a value and an amount obtained by hashing the signature of the sender and the public key of the receiver. As shown in FIG. 5, the proposed transaction consists _{of only the hash value of the sender's signature σ s} (sigSHash in FIG. 5), _{the hash value of the recipient's public key pub r} (pubRHash in FIG. 5), and the amount of the received amount. can The sender's public key pub _s is removed from the transaction, the signature hash value is used to verify the signature, and the public key hash value and amount can be stored as information about the recipient.

On the other hand, since a public key/signature pair is required for signature verification, in the present invention, {pub _s , σ _s } is transmitted together and used for verification in steps S200 and S300, which will be described in detail later, and after a certain period of time, {pub _s , σ _s } is proposed as a new way to destroy.

5, the transaction information TXinfo includes the transaction data itself (txdata in FIG. 5), the hash value of the transaction (hashvalue in FIG. 5), the verification result (v in FIG. 5), and the transaction. The block height (height in Fig. 5), the sender's public key and signature (pubS, sigS in Fig. 5), the recipient's public key (pubR in Fig. 5) to confirm the destination, and whether the transaction is stable or unstable There is a status field (status in FIG. 5) indicating whether it is unstable. This transaction information is kept in the Unconfirmed Transaction Pool. At this time, if the hash function is performed by grafting the Grover algorithm and the birthday attack, the specificity is lowered. Therefore, in the present invention, the same stability is maintained by increasing the length of the hash function (HashSizes in FIG. 5).

6 is a diagram illustrating a detailed flow of step S100 in a block chain transaction method in which the transaction size is reduced using a cryptographic hash algorithm according to an embodiment of the present invention, and FIG. 7 is an embodiment of the present invention. It is a diagram showing an algorithm for the implementation of step S100 of the block chain transaction method in which the transaction size is reduced using a cryptographic hash algorithm according to the As shown in FIG. 6, the block chain transaction method in which the transaction size is reduced using a cryptographic hash algorithm according to an embodiment of the present invention includes the steps of storing the hash value and amount of the recipient public key in the transaction data (S110) ), calling the signature function (S120), signing the hash value of the previous transaction, the recipient public key and the amount with the sender's private key (S130), and generating a hash value of the sender's signature and storing it in the transaction data (S140) ) may be implemented, and may further include a step (S150) of generating transaction information including transaction data and additional information about the transaction. In the present invention, a transaction may be created and propagated in a manner as shown in FIGS. 6 and 7 .

The input of the transaction creation algorithm is the sender's key pair {pub _s , priv _s } used for signing and verification, the receiver's public key pub _r and the amount received, the hash H of the previous TX referenced to use the coin (PrevTX), The output may be TXinfo, which is data about the transaction including the transaction TX.

In step S110, the hash value and the amount of the public key of the recipient may be stored in the transaction data. That is, in step S110, first, the hash value of the recipient's public key and the amount are put into TX (①, ② in FIG. 7). At this time, in the case of a block chain that does not exchange values according to the characteristics of the block chain, only the hash value of the recipient public key can be stored in the transaction data without the amount of money.

In step S120, the signature function may be called (3 in FIG. 7).

In step S130, the hash value of the previous transaction, the recipient's public key, and the amount can be signed with the sender's private key (④ in FIG. 7). At this time, in the case of a block chain that does not exchange value according to the characteristics of the block chain, the hash value of the previous transaction and the recipient public key can be signed with the sender's private key without an amount.

In step S140, a hash value of the sender's signature in step 130 may be generated and stored in the transaction data. That is, _{a hash value of the signature value σ s} is generated and input to the transaction ( ⑤ in FIG. 7 ). In this way, the transaction TX may be generated by performing steps S110 to S140.

In step S150, transaction information TXinfo including transaction data and additional information about the transaction may be generated. Here, the transaction information includes a sender public key and a sender signature, and may further include a receiver public key and a hash value of the transaction for receiver confirmation. More specifically, in step S150, TX is put in TXinfo including additional information about the transaction (⑥ in FIG. 7), and information for verification {pub _s , σ s } may be attached (⑦ and _{σ s in FIG. 7)} ⑧). _{You can attach pub r} to confirm the recipient (⑨ in FIG. 7), and add a hash value of the transaction (⑩ in FIG. 7).

A block chain may include a fixed block in which all transactions included in the block are in a stable state and an unfixed block including at least one unstable transaction. In the present invention, for verification in a non-fixed block, the sender's public key and sender's signature are attached to the transaction information TXinfo, and in the non-fixed block, the attached public key and signature pair {pub _s , σ _s } is used in the existing method ( For example, the block can be verified in the same way as P2PKH). When a non-fixed block becomes a fixed block, the attached sender public key and sender signature can be removed from the transaction.

In step S200, for verification in the non-fixed block, transaction information with the sender's public key and sender's signature attached may be stored in an unauthorized transaction pool, and the transaction may be propagated. That is, the transaction information TXinfo is added to the unapproved transaction pool, nodes propagate the information, and the transaction information can be kept in the unapproved transaction pool until the state changes stably.

In step S300, if the block containing the transaction is included in the fixed block, transaction information may be removed from the unauthorized transaction pool. More specifically, in step S200, the transaction information TXinfo generated in step S100 is stored in an unapproved transaction pool, and in step S300, when all transactions of blocks including transactions in the pool are in a stable state, Transaction information including the signature pair {pub _s , σ _s } can be removed from the unauthorized transaction pool.

8 is a diagram illustrating an algorithm for processing of step S300 in a block chain transaction method in which a transaction size is reduced using a cryptographic hash algorithm according to an embodiment of the present invention. The pool must be updated periodically to determine the status of transactions. The algorithm shown in FIG. 8 may perform a function of accepting the propagated transaction through verification and removing the stable transaction from the pool.

As shown in Fig. 8, as input of the protocol, there are TXinfo and TX, a security parameter k required to check the status of a transaction, and a tip height n of the main chain. As outputs, v, which is the verification result of the transaction, and status indicating the status of the transaction are updated, and TXinfo is displayed. First, in order to verify the transaction, it is possible to check whether the receiver's signature and the sender's public key recorded in the transaction are appropriate.

Specifically, if the signature hash value of TX is not the same as the signature hash value of TXinfo, or when the public key hash value of TX is not the same as the public key hash value of TXinfo, the protocol is terminated (① in FIG. 8) ). Call the signature verification function, put the sender's signature and public key in the transaction information (② to ④ in FIG. 8), and add the verification value back to the transaction information (⑤ and ⑥ in FIG. 8). If the verification value is not valid, the protocol is terminated ( ⑦ in FIG. 8 ), and transaction information is added to the pool only when valid ( ⑧ in FIG. 8 ). Also, if the block containing the transaction is included in the fixed block because the height of the block in the pool is lower than nk ( ⑨ in FIG. 8 ), the state of the transaction is changed to stable ( ⑩ in FIG. 8 ). In the future, TXinfo with stable status is removed from the unauthorized transaction pool.

When the transaction structure and verification method proposed in the present invention are introduced, block verification can be performed in the same manner as in the existing method because the sender's public key and signature pair required for transaction verification are attached to non-fixed blocks. Since the fixed block has little possibility of being changed, verification of the fixed block may be briefly performed. Hereinafter, the verification of the fixed block will be described in detail.

In a fixed block, verification of blocks and block headers can be performed. That is, when a fixed block is received, the validity of the block can be checked by verifying the block and the block header.

9 is a diagram illustrating an algorithm for verifying a fixed block in a block chain transaction method in which a transaction size is reduced using a cryptographic hash algorithm according to an embodiment of the present invention. That is, the algorithm of FIG. 9 is an example of a verification protocol for a fixed block block.

As illustrated in FIG. 9 , first, it is checked whether the hash of the previous block of the current block header matches the hash of the actual previous block, and if it does not match, a false value is returned (① in FIG. 9). In order to check whether the PoW of the generated block has been properly performed, it is checked whether the hash value of the block is smaller than the previously set target difficulty, otherwise a false value is returned (② in FIG. 9 ). In this way, the block is verified, and only when the verification is true (3 in FIG. 9), the block can be added.

Security Review

The block chain transaction method that reduces the transaction size using a cryptographic hash algorithm according to an embodiment of the present invention guarantees the integrity of each block through the chain structure like the previous block chain, and protects the attacker's tampered block through PoW Examine whether the traits that make it unacceptable are maintained. Two attack scenarios are assumed for review. It examines whether the integrity of the block chain is maintained in the present invention through an attack scenario that inserts a manipulated block in the middle, and examines whether the security of PoW is maintained through an attack scenario that takes over the main chain following the manipulated block.

Assume that a malicious user attempts to illegally steal assets by writing a crafted block following chain C, which is z distance from the tip height of the main chain. To make a main chain by adding a block to the chain C containing the manipulated block, the following conditions must be satisfied for both fixed and non-fixed blocks. In this case, each block is _{represented by B i} , and i means the height of the corresponding block. x is the number of blocks in the attacker's chain C, and k is the security parameter.

① For the fixed block B _i , the following Equation 4 must be satisfied for the nodes to accept the block.

② For the non-fixed block B _i , the following Equation 5 must be satisfied for the nodes to accept the block.

Based on the above conditions, review the attack scenarios a) and b) as follows.

a) An attack that inserts a manipulated block in the middle

_{If a manipulated block B i} ` is inserted in the middle of chain C and an existing chain is subsequently added, the following equation (6) must be satisfied for _{block B i+1.}

This is equivalent to obtain the 2 ^nd preimage of H (B _i) which satisfies the following equation (7), is against the security of the hash function.

Since all the conditions of Equation 7 must be satisfied for the fixed/non-fixed block, it is impossible to insert the modulated fixed/non-fixed block in the middle of the chain. Therefore, it can be seen that the integrity characteristics of the block chain are maintained the same in the present invention.

b) An attack that hijacks the main chain by creating blocks after the manipulated block

In order to take over the main chain, an attacker must create blocks faster than a good node, and the success rate of the attack depends on the consensus algorithm. The present invention generates blocks according to a PoW consensus algorithm. Since the following Equation 8 must be satisfied for the block B _i generated regardless of the fixed/non-fixed block, it can be considered that the fixed/non-fixed block is agreed upon according to PoW.

In PoW, the probability of an attacker catching up with a chain that is z blocks away depends on the probability p that a good node finds the next block, the probability q that the attacker finds the next block, and the number of blocks z that must catch up. The block generation probability has a high correlation with the hash rate of the attacker and the good node, and the present invention does not affect this. In addition, the number of blocks to be caught up z is the same as the security parameter k, which is a criterion for a transaction to be stably changed and usable, and in the present invention, k is an independent constant and is not changed according to the present invention. Therefore, the present invention generates a block according to PoW, and the probability that the attack b) succeeds in the present invention is the same as the existing 51% attack probability.

Therefore, the present invention does not significantly impair the inherent security of the existing blockchain and PoW.

Implementation and performance experiments

For the experiment of the present invention, the implemented quantum resistant blockchain (hereinafter BPQB) was developed/implemented based on bitcoin core version 0.15.1, which is an open source of bitcoin. Bitcoin core is a representative block chain with many limitations, such as a fixed block size and inability to execute smart contracts. Since the Bitcoin core shows the limitations of the block chain well, it was judged that it is suitable to study the areas that need to be improved in order to introduce quantum-resistant cryptography in the future, and this was selected as the base source.

In addition, the quantum resistance algorithm applied the lattice-based pqNTRUSign digital signature algorithm. pqNTRUSign is a modular grid-based digital signature scheme that uses NTRU lattice with a Gaussian sampler or a uniform sampler. Since pqNTRUSign has a smaller public key/signature size compared to other cryptographic algorithms, it will be possible to minimize the capacity of the unauthorized transaction pool to be borne by each node. Considering that all nodes receive transactions through signature verification, the signature verification time is short compared to other cryptographic algorithms, so we decided that the verification speed would be appropriate for implementing a practical blockchain. To measure the performance of BPQB, the signature and verification time were measured 50 times each in two PC test environments.

10 is a view showing the average signature and verification time and standard deviation in each experimental environment. The blockchain performs signature verification of all propagated transactions for transaction validation. Therefore, the most important factor in performance is the verification time. As shown in Figure 10, bitcoin 0.15.1 is faster than BPQB, but the average value of BPQB is ms (millisecond), which is a value of 10 ms or less, so it can be used practically. The signature time for BPQB is about 602 ms and bitcoin 0.15.1 is about 0.4 ms, showing a significant difference, but since it only affects the time that an individual creates a transaction, it is judged that there will not be much difficulty in practical use.

As described above, according to the block chain transaction method in which the transaction size is reduced by using the cryptographic hash algorithm proposed in the present invention, a transaction composed of the hash value of the recipient's public key, the hash value of the sender's signature, and the amount By propagating, it is possible to introduce various quantum-resistant digital signatures into the blockchain by significantly reducing the transaction size with bloated public keys and signature sizes, ultimately increasing the quantum-resistant digital signature compatibility of the blockchain and improving the overall blockchain. The size can also be reduced.

Various modifications and applications of the present invention described above are possible by those skilled in the art to which the present invention pertains, and the scope of the technical idea according to the present invention should be defined by the following claims.

S100: A step of generating a transaction consisting of a hash value of the recipient's public key and a hash value of the sender's signature
S110: Storing the hash value of the recipient public key in the transaction data
S120: Calling the signature function
S130: Signing the hash value of the previous transaction and the recipient public key with the sender private key
S140: A step of generating a hash value of the sender's signature and storing it in the transaction data
S150: generating transaction information including transaction data and additional information about the transaction
S200: For verification in a non-fixed block, storing the transaction information with the sender public key and the sender signature attached to the unauthorized transaction pool, and propagating the transaction
S300: When the block containing the transaction is included in the fixed block, the step of removing the transaction information from the unapproved transaction pool

Claims (9)

A blockchain-based system including a plurality of blockchain nodes, a blockchain transaction method that reduces the transaction size by using a cryptographic hash algorithm to reduce the burden on the size of the public key and signature when introducing quantum-resistant digital signatures,
If the transaction consists of only the hash value of the recipient's public key and the hash value of the sender's signature, or if the block chain converts the value into an amount using a monetary asset, the hash value of the recipient's public key, the hash value of the sender's signature, and Create and propagate the composed transaction,
(1) storing the hash value of the recipient's public key, or the hash value and the amount of the recipient's public key, in transaction data;
(2) calling the signature function;
(3) signing the hash value and the recipient public key of the previous transaction, or the hash value of the previous transaction, the hash value and the amount of the recipient public key, with the sender private key; and
(4) generating a hash value of the sender's signature of step (3) and storing it in the transaction data,
generating a transaction composed only of the hash value of the recipient public key and the hash value of the sender's signature, or consisting only of the hash value of the recipient's public key, the hash value of the sender's signature, and the amount
The blockchain is
Includes a fixed block in which all transactions included in the block are in a stable state and an unfixed block including at least one unstable transaction,
For verification in the non-fixed block, a sender public key and sender signature are attached, and when the non-fixed block becomes a fixed block, the attached sender public key and sender signature are removed from the transaction,
In the fixed block, a block chain transaction method that reduces the transaction size using a cryptographic hash algorithm, characterized in that the block and block header are verified to confirm the validity of the block. delete delete The method of claim 1, wherein after step (4),
(5) A block chain transaction method in which a transaction size is reduced using a cryptographic hash algorithm, characterized in that it further comprises the step of generating transaction information including the transaction data and additional information about the transaction. 5. The method of claim 4,
The transaction information includes a sender public key and a sender signature,
The transaction information is stored in an unapproved transaction pool, and when all transactions of blocks including transactions in the pool become stable, the transaction information is removed from the unauthorized transaction pool A blockchain transaction method that reduces the transaction size using a cryptographic hash algorithm. The method of claim 5, wherein the transaction information,
A block chain transaction method that reduces the transaction size using a cryptographic hash algorithm, characterized in that it further includes the recipient public key and the hash value of the transaction for verification of the recipient. delete delete In a blockchain-based system including a plurality of blockchain nodes, in order to reduce the burden on the size of public keys and signatures when introducing quantum-resistant digital signatures, it is a blockchain transaction method that reduces the transaction size using a cryptographic hash algorithm. ,
The block chain includes a fixed block in which all transactions included in the block are in a stable state and an unfixed block including at least one unstable transaction,
(a) A transaction consisting of only the hash value of the recipient's public key and the hash value of the sender's signature, or if the block chain converts the value into an amount using monetary assets and generating a transaction consisting of only the amount;
(b) for verification in the non-fixed block, storing transaction information with a sender public key and sender signature in an unauthorized transaction pool, and propagating the transaction; and
(c) if the block containing the transaction is included in the fixed block, removing the transaction information from the unauthorized transaction pool;
In step (a),
(1) storing the hash value of the recipient's public key, or the hash value and the amount of the recipient's public key, in transaction data;
(2) calling the signature function;
(3) signing the hash value and the recipient public key of the previous transaction, or the hash value of the previous transaction, the hash value and the amount of the recipient public key, with the sender private key; and
(4) generating a hash value of the sender's signature of step (3) and storing it in the transaction data,
generating a transaction composed only of the hash value of the recipient public key and the hash value of the sender's signature, or consisting only of the hash value of the recipient's public key, the hash value of the sender's signature, and the amount
For verification in the non-fixed block, a sender public key and sender signature are attached, and when the non-fixed block becomes a fixed block, the attached sender public key and sender signature are removed from the transaction,
In the fixed block, a block chain transaction method in which the transaction size is reduced using a cryptographic hash algorithm, characterized in that the block and block header are verified to confirm the validity of the block.

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