KR20210064803A - Leaderless block-chain consensus method and device - Google Patents

Abstract

A leaderless blockchain consensus method and a device thereof are disclosed. The leaderless blockchain consensus method comprises the following steps of: (a) calculating a random value for a current round; (b) selecting a block proposal node by using the calculated random value; (c) receiving a block generated from the block proposal node; and (d) verifying the received block and, if valid, adding a signature to a header of the block, and transmitting only block header information, to which the signature is added, to another node.

Description

Leaderless block-chain consensus method and device

The present invention relates to a leaderless blockchain consensus method and apparatus.

A blockchain is a list of records called blocks that are linked using encryption. Each block contains a cryptographic hash of the previous block, making the blockchain resistant to modification. By design, the blockchain is an open, decentralized ledger that enables efficient, verifiable, and permanent recording of transactions between two parties.

Writing a block to the blockchain requires the consensus of the majority of the network. Two conventional consensus protocols are mainly used.

The first is Nakamoto Consensus, or Proof of Work (PoW). PoW has high node scalability, but has disadvantages in terms of latency and throughput. To solve the shortcomings of Nakamoto Consensus, we explored the possibility of classical consensus protocols such as Byzantine Fault Tolerance (BFT) protocols. The pragmatic Byzantine Fault Tolerance (PBFT) protocol is an efficient solution to the Byzantine General's problem of operating in a weakly synchronous environment.

메시지 복잡도를 가지므로 노드의 수개 많은 블록 체인으로 적용할 수 없는 단점을 가지고 있다. However, PBFT has excellent performance,

Since it has message complexity, it has the disadvantage that it cannot be applied to several block chains of nodes.

(01) Republic of Korea Patent Publication No. 10-2033848 (2019.10.11.)

The present invention is to provide a leaderless blockchain consensus method and apparatus.

Another object of the present invention is to provide a leaderless blockchain consensus method and apparatus in which each node can independently select the same block proposer in a single round.

내에 블록 체인 합의가 가능하도록 할 수 있는 리더가 없는 블록 체인 합의 방법 및 그 장치를 제공하기 위한 것이다. In addition, the present invention provides even if the number of nodes increases

It is to provide a leaderless blockchain consensus method and device that can enable blockchain consensus within.

According to one aspect of the present invention, a leaderless blockchain consensus method is provided.

According to an embodiment of the present invention, (a) calculating a random value for the current round; (b) selecting a block proposal node using the calculated random value; (c) receiving a block generated from the block proposal node; and (d) verifying the received block and, if valid, adding a signature to the header of the block, and transmitting only the block header information to which the signature is added to another node. may be provided.

The random value for the current round may be calculated using the random value used in the previous round and the signature of the block generated in the previous round.

After step (d), the method further comprises the step of receiving a shared signature added to the block header from other neighboring nodes, but adding the block to the block chain when a valid signature is greater than or equal to a security threshold by analyzing the shared signature It may further include the step of

The security threshold may be set to half of the total number of shard members.

Steps (a) to (d) are performed in one round, but may be independently performed at each node.

When a valid block is not received from the block proposal node during the block waiting time, the method may include generating an empty block, signing it, and transmitting it to the other node.

In step (d), when two valid blocks are received from the block proposal node, only one block is verified and signed, and the other block can be ignored.

According to another aspect of the present invention, there is provided a device capable of agreeing on a blockchain without a leader.

According to an embodiment of the present invention, a memory for storing at least one instruction; a processor executing an instruction stored in the memory, the instruction comprising: (a) calculating a random value for a current round; (b) selecting a block proposal node using the calculated random value; (c) receiving a block generated from the block proposal node; and (d) after verifying the received block, if valid, adding a signature to the header of the block, and transmitting only the block header information to which the signature is added to another node may be provided.

By providing a leaderless blockchain consensus method and apparatus according to an embodiment of the present invention, each node can independently select the same block proposer in a single round.

내에 블록 체인 합의가 가능하도록 할 수 있다. In addition, the present invention provides even if the number of nodes increases

It can enable blockchain consensus within the

1 is a flowchart illustrating a branchless blockchain consensus method without a leader according to an embodiment of the present invention.
2 is a diagram illustrating block verification pseudocode according to an embodiment of the present invention;
3 is a diagram illustrating a method of selecting a block proposer in each node according to an embodiment of the present invention.
4 is a diagram illustrating a pseudo code for a block consensus process according to an embodiment of the present invention.
5 is a diagram illustrating a time until a block chain agreement according to an embodiment of the present invention.

As used herein, the singular expression includes the plural expression unless the context clearly dictates otherwise. In this specification, terms such as “consisting of” or “comprising” should not be construed as necessarily including all of the various components or various steps described in the specification, some of which components or some steps are It should be construed that it may not include, or may further include additional components or steps. In addition, terms such as "...unit" and "module" described in the specification mean a unit that processes at least one function or operation, which may be implemented as hardware or software, or a combination of hardware and software. .

In the present invention, without a leader, shard members (each node) independently generate random values in each round, and based on this, any one of the shard members can be independently selected as a block proposer. In addition, in the present invention, if a valid block generated by a block proposer is signed by a shard member (node) above the security threshold, the block can be added to the block chain as a valid consensus for all shard members. In the following, it should be understood that a block is arbitrary data, even if there is no separate description. It goes without saying that data can also be transactional data, and the format of the data itself can vary widely.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a flowchart illustrating a branchless blockchain consensus method without a leader according to an embodiment of the present invention, FIG. 2 is a diagram illustrating block verification pseudocode according to an embodiment of the present invention, and FIG. 3 is this It is a diagram illustrating a method of selecting a block proposer in each node according to an embodiment of the present invention, and FIG. 4 is a diagram illustrating a pseudo code for a block consensus process according to an embodiment of the present invention, FIG. 5 is a diagram illustrating the time until block chain agreement according to an embodiment of the present invention.

In step 110, each node 100 calculates a random value.

First, for convenience of understanding and explanation, it is assumed that each node 100 recovers and knows the list of public keys for all shard members.

This will first be briefly described.

In one embodiment of the present invention, a block proposer is selected in one round, and after the signature and verification of the block generated by the block proposer is completed, it may be added to the block chain. This will be more clearly understood by the following description.

)와 개인키를 가지고 있는 것을 가정하기로 한다.

이며, t는 보안 임계치라고 정의하기로 한다. Each node 100 has a verification vector (

) and a private key.

, and t is defined as the security threshold.

로 설정되는 것을 가정하기로 한다. 또한, m은 각 노드(즉, 샤드 구성원)의 크기(size)를 나타낸다. In addition, according to the Joint-Feldman DKG protocol,

Assume that it is set to . Also, m represents the size of each node (ie, shard member).

인 것을 가정하기로 하며,

는 서명 검증을 위해 이용될 수 있다. 각 노드(샤드 멤버)의 개인키에 대응하는 공개키(

)는 수학식 1에 의해 복구될 수 있다. the public key

It is assumed that

can be used for signature verification. The public key corresponding to the private key of each node (shard member) (

) can be recovered by Equation (1).

와 j에 의해 검증될 수 있다. Here, j represents the shard member index, and the shared signature generated by the shard member (j) is

and j can be verified.

Accordingly, in one embodiment of the present invention, it is assumed that each node has the list of public keys sorted from low to high according to the hash value of the public key after recovering the list of public keys of all shard members. .

Accordingly, each node 100 may calculate the random value of the current round based on the random value of the previous round. That is, each node 100 may calculate a random value by using the hash value of the random value used in the previous round.

For example, each node 100 may calculate a random value to be used in the current round using Equation (2).

는 이전 라운드에서 사용된 랜덤값을 나타내고,

는 이전 라운드에서 생성된 블록의 서명을 나타낸다. here,

represents the random value used in the previous round,

represents the signature of the block generated in the previous round.

Accordingly, each node 100 may calculate the random value used in the previous round and the result (hash value) of applying the signature of the previous round to the hash function as a random value.

In step 115, each node 100 selects a block proposer using the calculated random value.

For example, each node 100 may select a block proposer using Equation 3 below.

Here, mod() represents the remainder operator. That is, each node 100 may select a block proposer by performing a mod operation on a random value using the shard member size.

Since each node 100 calculates a random value by applying the same hash function with the same information and selects a block proposer with an index corresponding to the result of mod operation with the shard member size, the same result is derived (Fig. see 3).

To recap, the random value used in the previous round and the signature of the shard member of the last valid block in the previous round are known to all nodes. Accordingly, each node 100 may independently calculate a random value without a separate interaction. In addition, since each node 100 already knows the shard member list, each node 100 can select the same block proposer based on the same random value.

In step 120, each node 100 determines whether a valid block is received from the block proposer (block proposal node) within the block waiting time.

If a valid block is not received during the block wait time, in step 125, each node 100 signs the empty block and then erases the block wait time stamp.

For convenience of understanding and explanation, methods such as verifying and signing a block will be first described. As already described above, each node 100 may select a block proposer according to the same operation result. Accordingly, each node 100 already knows information about the selected block proposer.

과

를 우선 가정하기로 한다. 여기서,

는 이중선형 매핑 함수이다. 공개키는

의 엘리먼트이며, 서명은

의 엘리먼트인 것을 가정하기로 한다. two cycle groups

and

is to be assumed first. here,

is a bilinear mapping function. the public key

is an element of , and the signature is

Assume that it is an element of .

)를 해당 라운드의 랜덤값으로 설정하기로 한다. 즉,

가 블록 제안자의 정보인 것으로 가정하기로 한다. A generation point that is a random number (

) is set as the random value of the round. In other words,

It is assumed that is information of the block proposer.

), 검증 벡터(

) 및 공개키(

)를 가지고 있는 것을 가정하기로 한다. As already mentioned above, shard members use their own private key (

), the validation vector (

) and public key (

) is assumed to have

Each node can sign the message using the shared private key after applying the message to the hash function. If this is expressed as an equation, it is the same as in equation (4).

)를 가지고 있으므로, 이를 이용하여 서명(

)을 검증할 수 있다. 이를 수학식으로 나타내면, 수학식 5와 같다. Each node (shard member) has a public key (

), so use it to sign (

) can be verified. If this is expressed as an equation, it is as in Equation 5.

를 적용하여 도출된 결과와 각 노드가 메시지를 해시한 결과와 공개키를 검증 함수에 적용한 결과가 동일한지 여부를 판단하여 각 노드는 블록 제안자로부터 수신한 블록의 유효성을 검증할 수 있다.For example, in the verification function, the signature included in the block header received from the block proposer (the signature of the block proposer) and

Each node can verify the validity of the block received from the block proposer by judging whether the result derived by applying , the result of each node hashing the message and the result of applying the public key to the verification function are the same.

Each node (shard constituency) receives t different signatures based on “Lagrage interpolaton” for signature sharing, and can recover the aggregated signatures in the current round. If this is expressed as an equation, it is expressed as equation (6).

According to the property of "Lagrage interpolaton", the result of the aggregated signature is unique. Accordingly, the aggregated signature can be verified using the public key.

This can be expressed as Equation (7).

When a valid block is received during the block waiting time, in step 130, each node 100 verifies the block, adds a signature to the block header, and transmits it to a neighboring node.

The block proposer (block proposal node) selected by each node creates a block by inserting the block proposer's signature into the block header using the gossip protocol in the Bitcoin P2P network.

Any node 100 may receive a block generated from a block proposer (block proposal node). Here, for the block, the block proposer's signature may be included in the header.

)을 이용하여 블록에 포함된 서명을 검증할 수 있다. 즉, 블록이 수신되면 정직한 노드는 블록 제안자의 인덱스, 이전 블록에 대한 포인터 및 트랜잭션 리스트를 포함하여 블록의 유효성을 체크할 수 있다. The node that receives the block from the block proposer receives a verification vector and a random value (

) to verify the signature included in the block. That is, when a block is received, an honest node can check the validity of the block, including the block proposer's index, a pointer to the previous block, and a list of transactions.

In step 135, each node 100 determines whether a majority consensus on blocks received from the block proposer is completed.

After verifying the block, each node 100 adds a signature to the block header, and does not randomly transmit it. However, each node 100 shares the block header signature with the neighboring nodes and receives the signature list from the neighboring nodes.

That is, each node can transmit the signature list to all neighboring nodes after adding the signature to a list (referred to as a signature list for convenience) when a signature is shared from a neighboring node. That is, when any node receives a signature list from a neighboring node, the signature list may be updated and then transmitted again.

라운드 메시지 교환 후에 정직한 노드는 정직한 샤드 구성원(노드)로부터 t 이상의 서명 공유가 가능하다. For example, if each node has r neighbors,

After round message exchange, honest nodes can share more than t signatures from honest shard members (nodes).

Therefore, in one embodiment of the present invention, when more than half of all shard members have signed a block, it is considered that the shard members have agreed to record the block created by the block proposer in the block chain.

Accordingly, when t or more signatures are shared by each node 100 through the sharing of the signature list with neighboring nodes, it can be determined that the agreement on the corresponding block is completed. The pseudo code for this is shown in FIG. 4 .

If more than t valid signatures are shared during the signature waiting time, in step 140, each node 100 adds a block to the block chain.

However, if t or more valid signatures are not shared during the signature waiting time, in step 145, each node 100 signs an empty block and then resets the time stamp of the signature waiting time.

The pseudo code for block verification is shown in FIG. 2 .

로 가정하기로 한다. A time until consensus on a block will be described with reference to FIG. 5 . In order to have a strong shard that can withstand Byzantine faults, the size of the shard must be large. However, smaller shards are more advantageous in terms of transaction speed. Given the trade-off, we set the shard size to 400 nodes, and the security threshold is

to assume that

It is assumed that the connection bandwidth between each node is limited to 20Mbps, and the latency of all communication links is 100ms.

가 된다. 각 노드에는 20개의 이웃 노드가 있고,

라운드 내에서 정직한 노드는 다른 정직한 노드와 서명을 공유받을 수 있다. 따라서, 전체

의 시간이 필요하다. As shown in Figure 5, the time to transmit the block is

becomes Each node has 20 neighbors,

In a round, honest nodes can share signatures with other honest nodes. Therefore, the whole

time is needed

가 소요되므로, 블록이 합의되기까지 약 5초의 시간이 소요되는 것을 알 수 있다. Based on the above, a message can be received from the entire network after about 12 to 15 hops, with a latency of 100 ms on all communication links.

It can be seen that it takes about 5 seconds for the block to be agreed upon.

6 is a block diagram schematically illustrating the configuration of a node according to an embodiment of the present invention. Hereinafter, each node should be understood as a device constituting a shard network, and may be a computing device having computational power and communication capability.

Referring to FIG. 1 , according to an embodiment of the present invention, a node 100 includes a communication unit 610 , a memory 615 , and a processor 620 .

The communication unit 610 is a means for transmitting and receiving data with other devices (eg, other nodes) through a communication network.

For example, the communication unit 610 may receive a block from another node, a block header including a signature, and the like.

Also, the communication unit 610 may transmit a block header including its own signature to another node under the control of the processor 620 .

The memory 615 stores at least one instruction (program code) necessary to perform the leaderless branchless blockchain consensus method.

The processor 620 is a means for controlling the components (eg, the communication unit 610 , the memory 615 , etc.) of each node according to an embodiment of the present invention.

In addition, the instruction executed by the processor 620 may perform each step for the leaderless branchless blockchain consensus method described with reference to FIGS. 1 to 5 .

The apparatus and method according to an embodiment of the present invention may be implemented in the form of program instructions that can be executed through various computer means and recorded in a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, and the like, alone or in combination. The program instructions recorded on the computer readable medium may be specially designed and configured for the present invention, or may be known and available to those skilled in the computer software field. Examples of the computer-readable recording medium include magnetic media such as hard disks, floppy disks and magnetic tapes, optical media such as CD-ROMs and DVDs, and magnetic media such as floppy disks. - Includes magneto-optical media and hardware devices specially configured to store and execute program instructions, such as ROM, RAM, flash memory, and the like. Examples of program instructions include not only machine language codes such as those generated by a compiler, but also high-level language codes that can be executed by a computer using an interpreter or the like.

The hardware devices described above may be configured to operate as one or more software modules to perform the operations of the present invention, and vice versa.

So far, the present invention has been looked at focusing on the embodiments thereof. Those of ordinary skill in the art to which the present invention pertains will understand that the present invention can be implemented in modified forms without departing from the essential characteristics of the present invention. Therefore, the disclosed embodiments should be considered in an illustrative rather than a restrictive sense. The scope of the present invention is indicated in the claims rather than the foregoing description, and all differences within the scope equivalent thereto should be construed as being included in the present invention.

100: node
610: communication department
615: memory
620: processor

Claims (12)

(a) calculating a random value for the current round;
(b) selecting a block proposal node using the calculated random value;
(c) receiving a block generated from the block proposal node;
(d) if valid after verifying the received block, adding a signature to the header of the block, and transmitting only the block header information to which the signature is added to another node.
The method of claim 1,
The random value for the current round is,
A leaderless blockchain consensus method, characterized in that it is calculated using the random value used in the previous round and the signature of the block generated in the previous round.
The method of claim 1,
After step (d),
Further comprising the step of receiving a shared signature added to the block header from other neighboring nodes,
and analyzing the shared signature and adding the block to the block chain if the valid signature is greater than or equal to a security threshold.
4. The method of claim 3,
The security threshold is
A leaderless blockchain consensus method characterized by being set to half of the total number of shard members.
The method of claim 1,
Steps (a) to (d) are performed in one round, and each node is independently performed in a leaderless blockchain consensus method.
The method of claim 1,
and if a valid block is not received from the block proposal node during the block waiting time, generating an empty block, signing it, and transmitting it to the other node.
7. The method of claim 6,
In step (d),
When two valid blocks are received from the block proposal node, only one block is verified and signed, and the other block is ignored.
A computer-readable recording medium product on which a program code for performing the method according to any one of claims 1 to 7 is recorded.
a memory storing at least one instruction;
A processor that executes instructions stored in the memory,
The command is
(a) calculating a random value for the current round;
(b) selecting a block proposal node using the calculated random value;
(c) receiving a block generated from the block proposal node;
(d) After verifying the received block, if valid, adding a signature to the header of the block, and transmitting only the block header information to which the signature is added to another node.
10. The method of claim 9,
The random value for the current round is,
A node characterized in that it is calculated using the random value used in the previous round and the signature of the block generated in the previous round.
10. The method of claim 9,
After step (d),
Further comprising the step of receiving a shared signature added to the block header from other neighboring nodes,
A node further performing the step of analyzing the shared signature and adding the block to the block chain if the valid signature is greater than or equal to a security threshold.
12. The method of claim 11,
The security threshold is
A node characterized by being set to half of the total number of shard members.

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