WO2020082213A1

WO2020082213A1 - Network expandability blockchain implementation method

Info

Publication number: WO2020082213A1
Application number: PCT/CN2018/111248
Authority: WO
Inventors: 王泽宇; 管侠
Original assignee: 深圳市哈希树科技有限公司
Priority date: 2018-10-22
Filing date: 2018-10-22
Publication date: 2020-04-30

Abstract

Disclosed is a network expandability blockchain implementation method. The implementation method comprises: a segment and leadership election, consensus synchronization based on segment leadership, a reputation evaluation mechanism and a global synchronization algorithm. The embodiment of the present invention proposes a parallel chain structure, separating transaction and consensus into two chains, so as to improve the expandability of a blockchain network. The consensus part is performed in a reputation chain, and a reputation chain network pays attention to the security to support the high-speed transaction of a transaction chain network with the appropriate speed. Based on the advantages of the reputation evaluation mechanism, the embodiment of the present invention proposes a network slicing method based on the reputation evaluation mechanism. After the network slicing, the nodes with honesty and excellent performance are more likely to become the leader of the segment, thereby implementing the high throughput of the network without reducing the security of the blockchain network.

Description

Method for implementing network scalability block chain

Technical field

The present invention relates to the field of blockchain technology, and in particular to a network scalability blockchain implementation method.

Background technique

Blockchain is an open distributed ledger system, and multiple participants jointly maintain a set of ledger through a consensus mechanism. Taking the bitcoin system as an example, any electronic computer in the world can access the bitcoin network without authorization; each bitcoin node has a complete unified public account book backup of the entire network, recording all bitcoin transaction information For any node to conduct a transaction, the information needs to be synchronized to every node in the network, and the account books on all nodes can verify the behavior of this transaction and update it in time. In the blockchain network, the distribution of accounting rights is carried out through a consensus mechanism. At present, the more common blockchain consensus mechanisms include Proof of Work (POW), Proof of Stake (POS) and other methods, in which Proof of Work (POW) calculates a random number that meets the rules through hash operations and enumeration To obtain the accounting right of the current cycle, and all nodes are stored together after the entire network is verified. The advantage of proof-of-work (POW) is that it is completely decentralized, and all network nodes can enter and leave the network arbitrarily; the disadvantage is that it requires a lot of computing resources to obtain accounting rights, and the consensus period is long, and it cannot be used on a large scale.

Proof-of-stake (POS) is also a very representative method of allocating accounting rights. When generating new block accounting, network nodes attach their own addresses to the block network to prove the proportion of their corresponding equity. At the same time, the node uses the private key corresponding to the address to sign the block information to prove that it indeed owns the asset corresponding to the address. If a person has more rights and interests in the network, then under the assumption of a rational person, he will more actively maintain the normal operation of the network, so in the long run, the expected accounting right ratio of a node should be related to the rights and interests it holds. The proportions are equal. The shortcomings of proof-of-stake are also obvious. First of all, it will lead to the tendency of centralization of the network; secondly, the current proof-of-stake mechanism cannot resist the attack of computing power. A user with less equity can get much higher than his equity by investing a lot of computing power Proportionate accounting rights.

The traditional public blockchain is very weak in scalability and slow in transaction processing, which brings many inconveniences to the user experience.

Summary of the invention

The purpose of the embodiments of the present invention is to provide a network scalability block chain implementation method to solve the technical problem that the traditional public blockchain network scalability is very weak.

To achieve the above purpose, an embodiment of the present invention provides a network scalability blockchain implementation method, which includes: all verification nodes will be assigned to different groups at the beginning of each round of consensus cycle Form a number of shards; each shard elects a leader with a positive correlation probability based on the credit scores of the nodes in the corresponding group generated by historical behavior; the transaction initiator sends a transaction to the shard responsible for processing the transaction, and then the shard runs Based on the consensus synchronization algorithm led by shards, generate transaction blocks and reputation blocks; based on the behavior of all the validators in the consensus, all network verification nodes calculate the reputation score through the reputation evaluation mechanism and reach consensus on the reputation score; calculate in the reputation score After completion, the network verification node uses a common signature to generate the reputation block, which includes a reputation score, a list of confirmed transaction blocks, previous reputation blocks, and a common signature; and at the end of each consensus cycle , Each sharding group generates a status block, which records transaction blockchain and reputation blockchain Packet, then the network node based on the authentication, synchronization and update the stored credit value from all slice state blocks, the end of the next cycle begins a consensus.

Preferably, the verification node uses the hash value of the state block of the previous consensus cycle to generate a random number to introduce randomness, and then the verification node is randomly allocated to each shard.

Preferably, in the election mechanism of the leader, the verification node higher than the median of the credit score ranking becomes the shard leader with the probability that the credit score is positively correlated.

Preferably, each transaction has a unique identifier, an input UTXO list and an output UTXO list; all network verification nodes send the transaction to the shard responsible for input UTXO, and output the UTXO listed in these transactions.

Preferably, in the consensus synchronization algorithm based on the shard leadership, for the shard i, it is used to verify the transaction whose ID is divided by the remainder of the shard group number plus 1 plus 1.

Preferably, for on-chip transactions, the consensus synchronization algorithm based on shard leadership includes: the on-chip leader sends a list signature containing the transaction ID to all nodes on the chip; each network verification node checks the transactions in the transaction list ID and decide whether to accept, reject or fail to confirm the transaction; the network verification node will sign their decision and pass it to the on-chip leader; the leader generates a transaction block after collecting the decision of the verification node, the transaction block contains all network verifiers The signature of the leader and the signature of the leader; each network verification node checks the information of the relevant block; if more than half of the verification nodes issue an alarm, then the on-chip leader will be removed from the network, and the segment will regenerate the leader; when several A transaction block is generated, and no alarm is received, the network verification node will calculate the reputation value of the corresponding node, and generate a reputation block after co-signing.

Preferably, for cross-shard transactions, in the consensus synchronization algorithm based on shard leadership, the input shard sends the transaction list and the transaction decision list to the relevant output shard and other input shards.

Preferably, the transaction decision list of the network verification node contains multiple signatures, and each signature is used to sign a subset of the transaction list, and the transactions in a subset are sent to the same output fragment to reduce the bandwidth cost.

Preferably, the consensus synchronization algorithm based on sharding leadership uses parallel processing. If different transactions do not conflict with each other, the transactions will be processed in parallel in different blocks; the parallel processing method includes: each transaction list The transaction decision list and transaction block contain the number of iterations used to indicate the consensus period of the round; and the leader can send a new transaction list once it receives all the transaction decisions of the previous round from the network verification node.

Preferably, the formula for calculating the reputation score is:

Among them, l is the number of transactions generated after the reputation block in the previous reputation evaluation cycle; T (j) is the transaction amount of transaction j; S (j) is the scaling factor of transaction j, which is used to differentially reward or punish verification nodes Behavior; in the reputation score calculation, different scaling factors are set for different behaviors, so that the punishment for dishonest behavior is greater than the reward for honest behavior. For "unknown" decisions, the network verification node will neither obtain reputation scores nor lose reputation fraction.

The embodiments of the present invention have the following advantages:

1) The embodiment of the present invention proposes a parallel chain structure, which separates the transaction and the consensus into two chains to improve the scalability of the blockchain network; the consensus part is carried out on the reputation chain, and the reputation chain network focuses on security to take appropriate Speed supports high-speed transactions in the trading chain network;

2) The embodiment of the present invention uses a reputation evaluation mechanism to enhance the security and incentives of the blockchain network. On the one hand, the reputation consensus mechanism based on the historical performance of the nodes selects network nodes with honesty and excellent processing performance, while giving them more Expect network contributions and rewards; on the other hand, it is easier to find potential network spoilers and malicious nodes and remove them from the network in time to ensure the security of the blockchain network.

3) Based on the advantages of the reputation evaluation mechanism, an embodiment of the present invention proposes a network sharding method based on the reputation evaluation mechanism. After the network is sliced, honest and excellent nodes have a greater chance of becoming shard leaders, thereby achieving high network throughput At the same time, it does not reduce the security of the blockchain network.

BRIEF DESCRIPTION

1 is a flowchart of a method for implementing network scalability blockchain provided by an embodiment of the present invention;

2 is a schematic structural diagram of a blockchain network system for a network scalability blockchain implementation method provided by an embodiment of the present invention;

3 is a schematic diagram of a data structure of a reputation block (RB) and a status block (SB) and a multi-party signature in a synchronization process in a method for implementing network scalability blockchain provided by an embodiment of the present invention;

4 is a schematic diagram of the data structure of a transaction list (TxList), a transaction decision (TxDec), and a transaction decision list (TxDecSet) in a method for implementing network scalability blockchain provided by an embodiment of the present invention.

detailed description

The following describes the implementation of the present invention by specific specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

In the following description, for the purpose of illustration rather than limitation, specific details such as specific system structures, interfaces, and technologies are proposed so as to thoroughly understand the present invention. However, those skilled in the art should understand that the present invention can also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, circuits, and methods are omitted to avoid unnecessary details hindering the description of the present invention.

Example 1

Sharding technology is currently one of the most promising directions for improving the scalability of blockchains. By dividing the transactions on the network into different fragments, each node on the network only needs to process a small part of the transactions and verify the transactions in parallel with other network nodes to complete a large amount of work. The current sharding technology is mainly divided into: network sharding, which refers to the use of randomness, the network randomly extracts nodes to form fragments to prevent malicious nodes from overfilling a single shard; transaction sharding, in a UTXO-based system, the system sends The address of the author is assigned a shard to ensure that two double-spend transactions will be verified in the same shard. The system can easily detect double-spend transactions without any cross-shard communication; state sharding, in In the case of state sharding, each shard only retains a part of the state, which is the most difficult solution for sharding technology.

Referring to FIG. 1, a method for implementing network scalability blockchain provided by an embodiment of the present invention includes: sharding and leadership election, consensus synchronization based on sharding leadership, reputation evaluation mechanism, and global synchronization algorithm. The embodiment of the present invention builds a consensus mechanism through the reputation evaluation mechanism, based on which network segmentation is performed, the scalability of the blockchain network is improved, and the transaction processing speed of the network is improved.

Referring to FIG. 2, it is a schematic structural diagram of a blockchain network system for a network scalability blockchain implementation method provided by an embodiment of the present invention. First conduct sharding and leadership elections, and then consensus synchronization. At the same time, these two parts are included in the reputation mechanism designed by the embodiment of the present invention; the consensus ends, and finally the related transactions are packaged into the blockchain network synchronously globally.

Sharding and leader election. In this process, all the verification nodes will be assigned to different groups at the beginning of each consensus cycle to form a number of shards. Each sharding group will choose the leader of the group. The specific process is as follows: when a new consensus cycle e starts, all the verification nodes are assigned to different groups and the leader is elected with a positive correlation probability based on the credit scores generated by the historical behavior of the nodes in the group. In particular, the verification node uses the hash value of the previous state block to generate a random number to introduce randomness, and then the node is randomly allocated to each shard.

Further, during the random assignment of the verification nodes, a sharding algorithm is used to ensure that the total reputation value of each shard is substantially equal. The sharding algorithm includes:

Enter:

Random sequence:

Among them, e represents the e-th consensus cycle, SBH represents the hash value of each verification node status block, and k represents the k-th verification node;

Cumulative reputation score set:

Among them, w represents the cumulative reputation score calculation period, r represents the cumulative reputation score of each verification node, and k represents the kth verification node;

Output:

Total set of shard members: C = {c ₁ , c ₂ , ..., c _n }, where n represents the n-th shard and c represents the member set of each shard;

Shard leader set: L = {l ₁ , l ₂ , ..., l _n }, where n represents the nth shard and l represents the leader of each shard;

initialization,

Among them, i loops from 1 to n;

Use Seed ^e as a random generator RNG in the loop;

The elements in the cumulative reputation score set R ^w

Sort from largest to smallest to form a cumulative reputation score sorting set R ^sort :

Among them, sort means that the elements in the cumulative reputation score set R ^w

Sort by largest to smallest;

For each of R ^sort

carried out:

Find a sequence {t ₁ , t ₂ , ..., t _j } to form a subset of C

And meet:

Minimum value

Generate a random integer x from the random generator RNG;

Will work with each

The corresponding verification node v _{g is} assigned to

Where u = x divided by the remainder of j + 1;

The loop ends until all verification nodes are randomly assigned.

In addition, in the design of the leadership's election mechanism, the verification node higher than the median of the credit score ranking becomes the shard leader with the probability that the credit score is positively correlated. Specifically, the leadership election algorithm of the leadership election mechanism includes:

For each element c _n in the shard member total set C, execute:

rm = the median of the cumulative reputation scores of all the verification nodes included in c _n ;

For each verification node v _j included in c _n , execute:

in case,

Then, generate a random floating-point number from the random generator RNG:

in case,

Then, p _{i, j} = + ∞

When p _{i, m} = the minimum value in (p _{i, 1} , p _{i, 2} , ... p _{i, j} ), l _n = v _m ;

A c _n execution ends;

Until each element in the shard member ensemble C is traversed, the shard member ensemble C ends the execution loop;

The leadership election algorithm ends the cycle.

Based on the consensus synchronization of the shard leader, the transaction initiator sends a transaction (tx) to the shard responsible for processing the transaction, and then the shard runs the consensus synchronization algorithm based on the shard leader to generate transaction blocks and reputation blocks; in addition, For cross-slice transactions, the embodiment of the present invention uses an atomic cross-slice mechanism to ensure that double spending does not occur.

Referring to FIG. 4, similar to Bitcoin, in the embodiment of the present invention, each transaction (tx) will have a unique identifier, input UTXO list and output UTXO list; all network verification nodes send the transaction to the shard responsible for input UTXO, And output the UTXO listed in these transactions. UTXO (UnspentTransactionOutputs) is the basic unit of bitcoin transactions and is the unspent transaction output. It is a core concept of bitcoin transaction generation and verification. For shard i, in the embodiment of the present invention, it will be used to verify the transaction where the transaction ID is divided by the remainder of the number of shard groups plus one and is i. Since the input of UTXO may come from different shards, the implementation method involved in the embodiments of the present invention can handle intra-slice and cross-slice transactions.

Referring to FIG. 4, for on-chip transactions, the consensus synchronization algorithm based on shard leadership includes: the on-chip leader (shard leader l _j ) signs the list containing the transaction ID (TxList, Sig _lj is the shard leader l _j Signature) is sent to all nodes in the slice (shard member V _i ); each network verification node checks the transaction ID in the transaction list and decides whether to accept, reject or fail to confirm the transaction; the network verification node signs their decision (TxDec, Sig _i is the signature of each network verification node) and then passed to the on-chip leader; the leader generates a transaction block after collecting the decision of the verification node, the transaction block contains the signatures of all network verifiers (sig ₁ , sig ₂ … Sig _i … sig _m ) and the signature of the leader

Each network verification node checks the information of the relevant block; referring to Figure 3, if more than half of the verification nodes issue an alarm, the on-chip leader will be removed from the network and the shard will regenerate the leader; when there are several transaction areas When the block is generated and no alarm is received, the network verification node will calculate the reputation value of the corresponding node and generate a reputation block after co-signing.

Referring to FIG. 4, for cross-shard transactions, in the consensus synchronization algorithm based on shard leadership, the input shard sends the transaction list (TxList) and the transaction decision list (TxDecSet) to the relevant output shard and other input shards .

It is worth mentioning that, whether it is an on-chip transaction or a cross-chip transaction, the transaction decision list (TxDecSet) of the network verification node contains multiple signatures sig ₁ , sig ₂ … sig _i … sig _m , and each signature is used to Sign a subset of the transaction list, and the transactions in a subset are sent to the same output shard to reduce bandwidth costs; for a cross-shard transaction, if the relevant UTXO is not used or locked, the shard will be accepted , Otherwise the transaction will be rejected; both the input shard and the output shard will lock the relevant UTXO; when receiving the proof of acceptance of the transaction decision list containing the input UTXO from all relevant input shards, the output shard will be on the transaction block Add the transaction; when the input shard receives proof of acceptance from another related input shard, the related transaction and its UTXO will be released; and if one of the input shards rejects the transaction, the related input and output shard will be aborted transaction.

In order to further improve the transaction processing capability of the implementation method disclosed in the embodiment of the present invention, the consensus synchronization algorithm based on sharding uses parallel processing. If different transactions do not conflict with each other, transactions will be processed in parallel in different blocks. ; More specifically, the method of parallel processing includes: each transaction list, transaction decision list, and transaction block contains the number of iterations used to indicate the round of consensus cycle; and once the leader receives the previous round from the network verification node You can send a new list of transactions when all transactions are decided. Recalling the consensus protocol in the embodiment of the present invention, since the synchronization protocol is adopted, it ensures that before receiving the transaction list of the current round, most honest nodes have completed the work of sending the previous round of transaction decision list to the leader. Therefore, the network verification node can determine whether the new transaction list is valid.

The reputation evaluation mechanism, which effectively supports the aforementioned sharding and consensus synchronization scheme. Based on the consensus of the behavior of all validators, all network verification nodes calculate the reputation score through the reputation evaluation mechanism and reach consensus on the reputation score. Through cumulative reputation evaluation, the sharding and leadership election mechanism can be more secure and efficient. For an intra-segment transaction, after the end of the consensus period, the reputation score in the shard can be calculated separately and uniformly by all shard members based on the transaction conclusion set and transaction block, and the reputation score mechanism can be pluggable as needed. , The formula for calculating the reputation score is:

Among them, l is the number of transactions generated after the reputation block in the previous reputation evaluation cycle; T (j) is the transaction amount of transaction j; S (j) is the scaling factor of transaction j, used to differentially reward or punish the verification node behavior.

In the reputation score calculation, different scaling factors are set for different behaviors, so that the punishment for dishonest behavior is greater than the reward for honest behavior. Because illegal transactions are more dangerous than being rejected, if a certain network verification node gives “Yes” and most others give “No”, the network verification node will be given more punishment. For "unknown" decisions, network verification nodes will neither obtain reputation scores nor lose reputation scores, because these verification nodes usually have lower performance and cannot communicate in time (CPU, hard disk, bandwidth, etc.).

Refer to Figure 3, in the figure:

Is the reputation block of shard c ₁ in the e-1th consensus cycle,

Is the honest node reputation block of shard c ₁ in the e-th consensus cycle,

Is the reputation block of malicious node / potentially malicious node of slice c ₁ of the e-th consensus cycle,

Is the honest node state block of shard c ₁ ,

It is a malicious node / potentially malicious node status block of shard c ₁ , TB is an honest node transaction block, and TB ′ is a malicious node / potential malicious node transaction block. Nonce is an arbitrary one used only once in cryptography. Or a non-repetitive random value, after the reputation score calculation is completed, the network verification node uses a common signature to generate the reputation block, the reputation block includes a reputation score, a list of confirmed transaction blocks, previous reputation blocks and Sign together. Specifically, the generation of the reputation block is run by the block leader and the network verification node in two consecutive rounds, including announcement and commitment, challenge and response to the hash message signature of the reputation block of the previous cycle, and these signatures include consent The number of block verifiers and identity information, and the other shards to check the collective signature, if more than half of the network verification nodes sign on the block, then accept the transaction block; the reputation block provides evidence that more than half of the network verification nodes Accept transaction blocks. In a consensus cycle, sharding will pack reputation blocks into the reputation chain.

Global synchronization algorithm, at the end of each consensus cycle, each shard group generates a status block, packages the transaction blockchain and reputation blockchain records, and then the network verification node is based on the status area from all shards Block, synchronize and update the stored reputation value, and the next consensus cycle begins after the end. In order to reduce the huge network overhead for the entire blockchain node to communicate with each other, the network verification node uses a multi-party signature to generate the status block, and the network verification node uses a proof-of-work method to generate randomness in the status block The number is used for sharding and leadership elections in the next consensus cycle.

Although the present invention has been described in detail above with general description and specific embodiments, it can be modified or improved on the basis of the present invention, which is obvious to those skilled in the art. Therefore, these modifications or improvements made on the basis of not deviating from the spirit of the present invention belong to the scope claimed by the present invention.

Claims

A network scalability block chain implementation method, characterized in that the implementation method includes:

All verification nodes will be assigned to different groups to form several shards at the beginning of each round of consensus;

Each shard elects a leader with a positive correlation probability based on the credit scores of historical behaviors of the nodes in the corresponding group;

The transaction initiator sends the transaction to the shard responsible for processing the transaction, and then the shard runs a consensus synchronization algorithm based on the shard leader to generate transaction blocks and reputation blocks;

Based on the behavior of all validators in the consensus, all network verification nodes calculate the reputation score through the reputation evaluation mechanism and reach consensus on the reputation score;

After the reputation score calculation is completed, the network verification node uses a common signature to generate the reputation block, the reputation block includes a reputation score, a list of confirmed transaction blocks, a previous reputation block, and a common signature; and

At the end of each consensus cycle, each shard group generates a status block, packages the transaction blockchain and reputation blockchain records, and then the network verification node based on the status blocks from all shards, synchronizes and Update the stored reputation value and start the next consensus cycle after the end.
The method for implementing network scalability blockchain according to claim 1, wherein the verification node uses the hash value of the state block of the previous consensus cycle to generate a random number to introduce randomness, and then Verification nodes are randomly assigned to each shard.
A method for implementing network scalability blockchain according to claim 1, characterized in that, in the leadership's election mechanism, the verification node higher than the median of the credit score ranking becomes the probability of positive correlation of the credit score becomes Sharding leadership.
A method for implementing network scalability blockchain according to claim 1, characterized in that each transaction has a unique identifier, input UTXO list and output UTXO list; all network verification nodes send the transaction to the input UTXO And output the UTXO listed in these transactions.
A method for implementing network scalability blockchain according to claim 1, wherein in the consensus synchronization algorithm based on shard leadership, for shard i, it is used to verify the transaction ID divided by the shard The remainder of the group number is increased by 1 for the transaction of i.
A method for implementing network scalability blockchain according to claim 5, characterized in that, for on-chip transactions, the consensus synchronization algorithm based on shard leadership includes:

The leader in the chip sends the list signature containing the transaction ID to all nodes in the chip;

Each network verification node checks the transaction ID in the transaction list and decides whether to accept, reject or fail to confirm the transaction;

The network verification node will sign their decision and pass it to the on-chip leader;

The leader generates a transaction block after collecting the decision of the verification node. The transaction block contains the signatures of all network verifiers and the signature of the leader;

Each network verification node checks the relevant block information;

If more than half of the verification nodes issue an alarm, the on-chip leader will be removed from the network, and the shard will regenerate the leader;

When several transaction blocks are generated and no alert is received, the network verification node will calculate the reputation value of the corresponding node and generate a reputation block after co-signing.
A method for implementing network scalability blockchain according to claim 5, characterized in that, for cross-shard transactions, in the consensus synchronization algorithm based on shard leadership, input shards will be a transaction list and a transaction decision list Send to the relevant output shard and another input shard.
A method for implementing network scalability blockchain according to claim 6 or 7, wherein the transaction decision list of the network verification node contains multiple signatures, and each signature is used to sign a transaction list In a subset, transactions in a subset are sent to the same output shard to reduce bandwidth costs.
A method for implementing network scalability blockchain according to claim 6 or 7, characterized in that the consensus synchronization algorithm based on shard leadership adopts parallel processing, if different transactions do not conflict with each other, then Transactions will be processed in parallel in different blocks; the parallel processing method includes:

Each transaction list, transaction decision list, and transaction block contains the number of iterations used to indicate the round of consensus cycles; and

Once the leader receives all the transaction decisions of the previous round from the network verification node, it can send a new transaction list.
A method for implementing network scalability blockchain according to claim 1, wherein the formula for calculating the reputation score is:

Among them, l is the number of transactions generated after the reputation block in the previous reputation evaluation cycle;

T (j) is the transaction amount of transaction j; S (j) is the scaling factor of transaction j, used to differentially reward or punish the behavior of the verification node;

In the reputation score calculation, different scaling factors are set for different behaviors, so that the punishment for dishonest behavior is greater than the reward for honest behavior. For "unknown" decisions, the network verification node will neither obtain reputation score nor lose reputation score.