KR20210033846A - Blockchain transaction method with reduced transaction size using cryptographic hash algorithm - Google Patents

Abstract

The present invention relates to a blockchain transaction method for reducing a transaction size using a cryptographic hash algorithm. The blockchain transaction method generates and propagates a transaction consisting of a hash value of a public key of a recipient, a hash value of the signature of a sender, and the amount.

Description

Blockchain transaction method with reduced transaction size using cryptographic hash algorithm {BLOCKCHAIN TRANSACTION METHOD WITH REDUCED TRANSACTION SIZE USING CRYPTOGRAPHIC HASH ALGORITHM}

The present invention relates to a block chain transaction method, and more specifically, to a block chain transaction method in which the transaction size is reduced using a cryptographic hash algorithm.

For digital signatures, digital signature schemes based on asymmetric cryptographic algorithms such as RSA and ECC are usually used. However, when a practically usable quantum computer is implemented, the performance of the processor can be vastly improved, and it is a problem that cannot be computed with an existing computer using quantum algorithms such as the Shores algorithm and the Grovers algorithm. Can be solved. The Shore algorithm can compute factorization and discrete log problems, which are the basis of public key cryptographic algorithms, within polynomial time, so RSA and ECC become weak cryptographic algorithms. Grover's 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 digital signature scheme (ECDSA). Distributed ledgers and blockchains using this cannot be expected to be used for a long time when quantum computers are considered. In preparation for this, research is underway to introduce Post-Quantum Cryptography to the blockchain. The combination of quantum resistant cryptography and blockchain is called a post-quantum blockchain, and is resistant to quantum algorithm attacks 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, there may be a problem with a large public key and signature size, or a problem that the signature verification time is lengthened. Therefore, it is necessary to develop a technology that can solve this problem.

Meanwhile, as a prior art related to the present invention, Patent 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. 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, the large public key and Cryptography that can significantly reduce the size of transactions with signature sizes to introduce various quantum-resistant electronic signatures into the blockchain, and ultimately increase the compatibility of quantum-resistant electronic signatures of the blockchain and reduce the overall size of the blockchain. Its purpose is to provide a blockchain transaction method that reduces the size of a transaction by using a hash algorithm.

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,

As a transaction method in a blockchain-based system including a plurality of blockchain nodes,

The constructional feature is that a transaction consisting of the hash value of the recipient's public key and the hash value of the sender's signature is generated and propagated.

Preferably,

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

(2) calling a 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 in step (3) and storing it in the transaction data,

A transaction consisting of the hash value of the recipient public key and the hash value of the sender's signature may be generated.

Preferably,

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

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 the amount of the recipient public key in transaction data;

(2) calling a signature function;

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

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

A transaction consisting of the hash value of the recipient public key, the hash value of the sender's signature, and the amount may be generated.

More preferably, after step (4),

(5) The step of generating transaction information including the transaction data and additional information on the transaction may be further included.

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 a block including a transaction in the pool become stable, the transaction information may be removed from the unauthorized transaction pool.

Even more preferably, the transaction information,

The recipient public key for confirming the recipient and a hash value of the transaction may be further included.

Preferably, the block chain,

All transactions included in the block may include a fixed block in a stable state and an unfixed block including at least one unstable transaction.

More preferably,

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

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

As a transaction method in a blockchain-based system including a plurality of blockchain nodes,

The blockchain 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) storing the transaction information attached to the sender public key and the sender signature in an unauthorized transaction pool for verification in the non-fixed block, 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 is another structural feature.

According to the blockchain transaction method in which the transaction size is reduced by using the cryptographic hash algorithm proposed in the present invention, a transaction consisting of the hash value of the recipient public key, the hash value of the sender's signature, and the amount is generated and propagated. By drastically reducing the size of transactions with public keys and signature sizes, various quantum-resistant electronic signatures can be introduced into the blockchain, and ultimately, quantum-resistant electronic signature compatibility of the blockchain can be increased, and the size of the overall blockchain can also be reduced. have.

1 is a diagram showing an average transaction size, a block size, and the overall size of the chain for a quantum resistant electronic signature scheme predicted and displayed.
2 is a diagram illustrating an existing transaction structure.
3 is a view showing a fixed block and a non-fixed block in the main chain.
4 is a diagram illustrating a flow of 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.
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 showing 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 showing an algorithm for implementing step S100 of 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.
8 is a diagram showing an algorithm for processing 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 showing 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.
10 is a diagram showing the average signature and verification time and standard deviation in each experimental environment.

Hereinafter, preferred embodiments will be described in detail with reference to the accompanying drawings so that those of ordinary skill in the art may easily implement the present invention. 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 subject matter 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 said to be connected to another part, this includes not only the case that it is directly connected, but also the case that it is indirectly connected with another element interposed therebetween. In addition, the inclusion of certain components means that other components may be further included rather than excluding other components unless specifically stated to the contrary.

The present invention relates to a blockchain transaction method in which a transaction size is reduced using a cryptographic hash algorithm, and a blockchain transaction method in which the transaction size is reduced using a cryptographic hash algorithm according to a feature of the present invention includes a memory and a processor. It can be configured with software that is recorded 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 smartphone, 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. Nodes can be implemented as servers or computers, and each node is equipped with a blockchain, which can be referred to as a blockchain node. In a blockchain-based system including multiple blockchain nodes, a node creates a transaction according to an event such as payment, each node receives and verifies the transaction information, and propagates the transaction to the next designated node. .

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 on introducing Post-Quantum Cryptography into the blockchain is underway.

All quantum resistant ciphers have a larger public key size and signature size than ECDSA. Public keys differ by a minimum of 2 times and a maximum of 64 times, and signatures differ by a minimum of 22 times and a maximum of 1920 times. If such 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 proportionately. Therefore, it is expected that the resources and costs borne by one node will be amplified as the block chain storage space becomes very large.

1 is a diagram illustrating predicted and displayed average transaction size, block size, and overall chain size for a quantum resistant electronic signature scheme. Figure 1 shows that at 09:00 on April 14, 2019 (GMT+0900), the total size of the Bitcoin blockchain is about 207.66 GB, the average number of transactions is 2,763, and the number of blocks is 578,151, each quantum resistant electron For the signature scheme, the average transaction size, block size, and overall size of the chain were estimated. Assuming that the number of blocks equal to the current bitcoin is accumulated, as can be seen in FIG. 1, the size of the entire chain for the quantum resistant electronic signature scheme was estimated to be about 54 Tb at the minimum and 1,924 Tb at the maximum. This increase in the size of the public key/signature pair will increase the weight of the blockchain, which will be a significant burden. Therefore, there is a need for a way to reduce the burden on the size of the public key/signature.

A blockchain 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 blockchain-based system including a plurality of blockchain nodes, and includes a hash value of a recipient public key and a sender. A transaction consisting of the hash value of the signature can be created and propagated. However, when the blockchain transacts by converting value into an amount using a monetary asset, it can 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. That is, in the present invention, in the case of a block chain that does not exchange value according to the characteristics of the block chain, a transaction is constructed with the hash value of the recipient's public key and the hash value of the sender's signature, and value In the case of a blockchain that converts to an amount and transacts, in addition to the hash value of the recipient's public key and the hash value of the sender's signature, a transaction can be formed by further including an amount.

Therefore, according to the blockchain transaction method in which the transaction size is reduced using the cryptographic hash algorithm proposed in the present invention, the hash value of the recipient public key rather than the recipient public key, and the public key of the sender's signature rather than the sender's signature, are included. By using a cryptographic hash algorithm, the size of transactions with large public keys and signature sizes can be drastically reduced. Therefore, various quantum resistant electronic signatures can be introduced into the blockchain, ultimately increasing the compatibility of the blockchain's quantum resistant electronic signature, and reducing the overall size of the blockchain.

In the following, for convenience of explanation, a transaction structure including an amount is basically described, and in the case of a blockchain that does not exchange value, the rest can be processed in the same manner, except that the amount is excluded.

2 is a diagram illustrating an existing transaction structure. In the structure as shown in FIG. 2, a transaction includes all information such as a sender's signature, a sender's public key, a recipient's public key, and an amount. On the other hand, in the blockchain 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 a cryptographic hash algorithm. By proposing a transaction structure that can be used, the transaction size can be significantly reduced.

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 of expressing a block structure, and the present invention follows the following structure as a basic block structure.

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

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

Transaction: Transaction is indicated by TX. In order to use the coin, the sender sometimes calls a transaction containing the previously received coin transmission history, and in this case, the called transaction is represented by PrevTX.

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

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

Hash function: 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. The hash function can be considered safe only when three properties are satisfied: (a) preimage resistance, (b) 2nd-preimage resistance, and (c) collision resistance.

Signature: Transactions usually contain the sender's signature. In the present invention, _{the element that enters the sender's signature σ s} is abbreviated and can be made through Equation 1 below.

That is, the hash value H (PrevTX) of the previous transaction containing the reception details of the coin to be used is put for reference, and the recipient's public key pub _r and the amount amount are signed with the sender's private key priv _s. This allows us to derive _{the signature σ s.}

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

Verification of the node's public key pub and signature σ results in a verification value v, where 0 means true and 1 means false. That is, if v=0, the transaction is valid.

Security parameter: When a transaction is included in a block, the transaction is said to have been confirmed. In addition, when a block is added following a block containing a transaction, the confirmation number increases by the number of blocks added. As the number of approvals increases, the possibility of a transaction being manipulated decreases, and when the number of approvals is more than k, the status of the 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 and can be set by the developer/operator.

In Equation 3, if the number of approvals of the 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 corresponding block is called a fixed block. In other words, a fixed block refers to a block that is more than k blocks away from the tip of the main chain. In addition, blocks that are less than k from the tip of the main chain are called unfixed blocks, and TX included in the unfixed blocks is unstable.

3 is a diagram showing a fixed block and a non-fixed block in the main chain. As shown in Figure 3, the blockchain is an unfixed block including at least one or more fixed blocks and unstable transactions in which all transactions included in the block are in a stable state. It 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 above-described concept.

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

In step S100, a transaction consisting of a hash value of a recipient public key and a hash value of a sender's signature may be generated. At this time, when the blockchain transacts by converting the value into an amount using a monetary asset, a transaction consisting of the hash value of the recipient 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, a new transaction structure and consensus mechanism for applying quantum resistant digital signatures is proposed. Simplifying the structure of the existing transaction consists of the sender's signature and public key pair, the recipient's public key, and the amount of remittance. As shown in Fig. 2, the components of an existing transaction are largely divided into two types. There is a sender's signature σ _s (sigS in Fig. 2), a 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 on the recipient of the amount pubR), the amount of the received amount amount is recorded. At this time, the signature is the hash value of the previous transaction, the recipient's public key, and the signed value.

However, if the quantum resistant cipher is applied to the existing structure as it is, as described above, the size of the transaction may be enlarged. Therefore, in the present invention, the public key/signature size is reduced by proposing a transaction consisting of a value and amount obtained by hashing the sender's signature and the receiver's public key. As shown in FIG. 5, the proposed transaction consists only _{of 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. I can. The sender's public key pub _s may be removed from the transaction, the signature hash value may be stored for signature verification purposes, and the public key hash value and amount may be stored as information about the recipient.

Meanwhile, since a public key/signature pair is required for signature verification, in the present invention, {pub _s and σ _s } are transmitted together and used for verification in steps S200 and S300 that will be described in detail later, and after a certain period of time, {pub _s We propose a new method to destroy, σ _{s }.}

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. Block height (height in FIG. 5), sender's public key and signature (pubS, sigS in FIG. 5), recipient's public key to verify destination (pubR in FIG. 5), and whether the transaction is stable (stable) unstable There is a status field (status in FIG. 5) indicating whether it is unstable. This transaction information is stored in the Unconfirmed Transaction Pool. At this time, if the hash function is combined with the Grover algorithm and the birthday attack, the ratio is lowered. Therefore, in the present invention, it is intended to maintain the same stability by increasing the length of the hash function (HashSizes in FIG. 5).

6 is a diagram showing 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. A diagram showing an algorithm for the implementation of step S100 of the blockchain transaction method in which the transaction size is reduced by using the cryptographic hash algorithm according to the following. 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 storing a hash value and an amount of a recipient public key in 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 the hash value of the sender's signature and storing it in the transaction data (S140) ), and generating transaction information including transaction data and additional information on the transaction (S150). In the present invention, transactions can 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 recipient's public key pub _r and the amount received, the hash H (PrevTX) of the previous TX referenced to use the coin, The output can be TXinfo, which is data about transactions including transaction TX.

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

In step S120, it is possible to call the signature function (3 in Fig. 7).

In step S130, the hash value, the recipient public key, and the amount of the previous transaction may be signed with the sender private key (4 in FIG. 7). At this time, in the case of a blockchain that does not exchange value according to the characteristics of the blockchain, 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 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 on 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 for verifying the recipient and a hash value of the transaction. More specifically, in step S150, TX is put into TXinfo including additional information on the transaction (6 in FIG. 7), and information for verification {pub _s , σ _s } may be attached (7 in FIG. 7 and ⑧). _{It is possible to attach pub r} for identifying the recipient (⑨ in Fig. 7) and add the hash value of the transaction (⑩ in Fig. 7).

The blockchain 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 or more unstable transactions. In the present invention, for verification in a non-fixed block, the sender public key and the 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 } are used in the conventional method ( For example, the block can be verified in the same way as P2PKH). When the 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, the sender public key and transaction information attached with the sender's signature may be stored in an unauthorized transaction pool, and the transaction may be propagated. That is, the transaction information TXinfo is added to the unauthorized transaction pool, the node propagates the information, and the transaction information can be stored in the unauthorized transaction pool until the state changes stably.

In step S300, if the block containing the transaction is included in the fixed block, the 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 unauthorized transaction pool, and in step S300, when all transactions of the block containing the transaction in the pool become stable, Transaction information including signature pairs {pub _s , σ _s } can be removed from the unauthorized transaction pool.

8 is a diagram illustrating an algorithm for processing 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 needs to be updated periodically to understand the status of the transaction. The algorithm shown in FIG. 8 may perform a function of accepting a propagated transaction through verification and removing a stable transaction from the pool.

As shown in FIG. 8, inputs of the protocol include 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 output, v, which is the verification result of the transaction, and the 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 recorded in the transaction and the sender's public key are appropriate.

Specifically, when the signature hash value of TX is not the same as the signature hash value of TXinfo, or 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 to the transaction information again (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 if it is valid (8 in Fig. 8). In addition, when the height of the block containing the transaction in the pool is lower than nk and is included in the fixed block (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 pool of unauthorized transactions.

When the transaction structure and verification method proposed in the present invention are introduced, the sender's public key and signature pair required for transaction verification are attached to the non-fixed block, so that the block verification can be performed in the same manner as the existing method. Since the fixed block has almost no possibility of change, the fixed block can be briefly verified. Hereinafter, the verification of the fixed block will be described in detail.

In the fixed block, the block and the block header can be verified. That is, when a fixed block is received, the validity of the block can be verified by performing verification on 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 previous block hash of the current block header matches the actual hash of the previous block, and if not, a false value is returned (1 in FIG. 9). In order to check whether the PoW of the generated block is properly performed, it is checked whether the hash value of the block is smaller than the previously set target difficulty level, and if not, a false value is returned (2 in FIG. 9). In this way, the block is verified, and the block can be added only when the verification is true (③ in FIG. 9).

Security review

The blockchain transaction method in which the transaction size is reduced using a cryptographic hash algorithm according to an embodiment of the present invention guarantees the integrity of each block through a chain structure as in the previous block chain, and protects the attacker's forged blocks through PoW. Examine whether the characteristics that make it difficult to accept are maintained. Two attack scenarios are assumed for review. In the present invention, the integrity of the block chain is maintained through an attack scenario in which a manipulated block is inserted in the middle, and whether the security of the PoW is maintained through an attack scenario in which the manipulated block is subsequently hijacked the main chain.

Suppose a malicious user attempts to illegally steal assets by creating a manipulated block following Chain C, which is z away from the tip height of the main chain. In order to make the main chain by adding a block to the chain C containing the manipulated block, the following conditions must be satisfied for the fixed block and the non-fixed block. At this time, 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 nodes accept the block only when the following Equation 4 is satisfied.

② For the non-fixed block B _i , the nodes accept the block only when the following equation (5) is satisfied.

According to the above conditions, review attack scenarios a) and b) as follows.

a) Attack that inserts a manipulated block in the middle

_{Assuming that the manipulated block B i} `is inserted in the middle of the chain C and the existing chain is then 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 blockchain 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 seize the main chain, an attacker must create a block faster than a good node, and the attack success rate depends on the consensus algorithm. The present invention generates a block according to the PoW consensus algorithm. Since the following Equation 8 must be satisfied for the block B _i generated regardless of the fixed/non-fixed blocks, it can be seen that the fixed/non-fixed blocks are agreed upon along the PoW.

In PoW, the probability that an attacker catches up to a chain 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 of the present invention does not affect this. In addition, the number of blocks z to be caught up is the same as the security parameter k, which is a criterion at which the transaction is stably changed and usable. 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 experiment

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

In addition, a lattice-based pqNTRUSign digital signature algorithm was applied to the quantum tolerance algorithm. pqNTRUSign is a modular lattice-based electronic signature scheme that uses NTRU lattice with a Gaussian sampler or a uniform sampler. Since pqNTRUSign has a smaller public key/signature size than other cryptographic algorithms, it will be able 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 shorter than that of other cryptographic algorithms, so it was determined 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 experimental environments.

10 is a diagram showing the average signature and verification time and standard deviation in each experimental environment. Blockchain performs signature verification of all transactions that are propagated to verify transaction validity. Therefore, the most important factor in the performance area is verification time. As shown in FIG. 10, bitcoin 0.15.1 is faster than BPQB, but since the average value of BPQB is less than 10 ms in ms (millisecond), it may be practically used. The signing time is about 602 ms for BPQB and about 0.4 ms for bitcoin 0.15.1, but this only affects the time when an individual creates a transaction.

As described above, according to the blockchain transaction method in which the transaction size is reduced using the cryptographic hash algorithm proposed in the present invention, a transaction consisting of the hash value of the recipient public key, the hash value of the sender's signature, and the amount is generated. By propagating, it is possible to introduce a variety of quantum resistant electronic signatures into the blockchain by drastically reducing the size of transactions with large public keys and signature sizes, ultimately increasing the compatibility of quantum resistant electronic signatures of the blockchain, and You can also reduce the size.

The present invention described above can be modified or applied in various ways by those of ordinary skill in the technical field to which the present invention belongs, and the scope of the technical idea according to the present invention should be determined by the following claims.

S100: Step of generating a transaction consisting of a hash value of the recipient public key and a hash value of the sender's signature
S110: Storing the hash value of the recipient public key in transaction data
S120: Step of calling the signature function
S130: Signing the hash value of the previous transaction and the recipient public key with the sender private key
S140: 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 on the transaction
S200: For verification in a non-fixed block, storing the sender public key and the transaction information attached to the sender's signature in an unauthorized transaction pool, and propagating the transaction
S300: If the block containing the transaction is included in the fixed block, removing the transaction information from the unauthorized transaction pool

Claims (9)

As a transaction method in a blockchain-based system including a plurality of blockchain nodes,
A blockchain transaction method in which a transaction size is reduced using a cryptographic hash algorithm, characterized in that a transaction consisting of a hash value of a recipient public key and a hash value of a sender's signature is generated and propagated. The method of claim 1,
(1) storing the hash value of the recipient public key in transaction data;
(2) calling a 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 in step (3) and storing it in the transaction data,
A blockchain transaction method in which a transaction size is reduced using a cryptographic hash algorithm, characterized in that generating a transaction consisting of the hash value of the recipient public key and the hash value of the sender's signature. The method of claim 1,
The blockchain uses monetary assets to convert values into amounts and transact,
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 the amount of the recipient public key in transaction data;
(2) calling a signature function;
(3) signing the hash value, the recipient public key, and the amount of the previous transaction with the sender private key; And
(4) generating a hash value of the sender's signature in step (3) and storing it in the transaction data,
A blockchain transaction method in which a transaction size is reduced using a cryptographic hash algorithm, characterized in that generating a transaction consisting of the hash value of the recipient public key, the hash value of the sender's signature, and the amount. The method of claim 2 or 3, wherein after step (4),
(5) A blockchain transaction method in which the transaction size is reduced using a cryptographic hash algorithm, further comprising generating transaction information including the transaction data and additional information on the transaction. The method of claim 4,
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 of a block containing a transaction 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,
Blockchain transaction method in which the transaction size is reduced using a cryptographic hash algorithm, characterized in that it further includes the recipient public key for confirming the recipient and a hash value of the transaction. The method of claim 1, wherein the block chain,
A cryptographic hash algorithm, characterized in that all transactions included in the block include a fixed block in a stable state and an unfixed block including at least one unstable transaction. Blockchain transaction method that reduces the transaction size by using. The method of claim 7,
For verification in the non-fixed block, a sender public key and a 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 a transaction. A blockchain transaction method that reduces the transaction size using a hash algorithm. As a transaction method in a blockchain-based system including a plurality of blockchain nodes,
The blockchain 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) storing the transaction information attached to the sender public key and the sender signature in an unauthorized transaction pool for verification in the non-fixed block, and propagating the transaction; And
(c) If the block containing the transaction is included in the fixed block, a block chain in which the transaction size is reduced using a cryptographic hash algorithm, comprising the step of removing the transaction information from the unauthorized transaction pool. Transaction method.

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