JP7073240B2 - Blockchain management system, blockchain management method and blockchain management program - Google Patents

Description

The present invention relates to a system, method and program for managing a plurality of blockchains.

Conventionally, a blockchain, which is a distributed database, has been proposed as a data recording method that is difficult to falsify, and is used in various systems (see, for example, Non-Patent Documents 1 to 3).

Satoshi Nakamoto. Bitcoin: A peer-to-peer electronic cash system, 2008. Somplinsky, Y. et al. , Zohar, A. : Accelerating bitcoin's transaction processing. Fast money grows on stories, not chains. IACR Cryptography ePrint Archive 2013 (2013) 881. Lewenberg, Y. et al. , Sampolinsky, Y. , Zohar, A. : INCLUSIVE block chain protocols. In: Financial Cryptography and Data Security-19th International Conference, FC2015, San Juan, Puerto Rico, January 26-30, 2015, Revised Select. (2015) 528-547.

Normally, in blockchain, consensus building is performed by users by a predetermined consensus algorithm in order to guarantee the validity of the recorded data.
However, when local blockchains are operated by multiple organizations (groups), the risk of collusion attacks in consensus increases as the scale of each blockchain decreases, resulting in a decrease in reliability.

An object of the present invention is to provide a blockchain management system, a blockchain management method, and a blockchain management program that can improve the reliability of each of a plurality of blockchains.

In the blockchain management system according to the present invention, a group consisting of a plurality of nodes belongs to a different blockchain from each other, and each node reaches a consensus for the block when the block of the blockchain to which the own node belongs is generated. As a participant, in addition to the node belonging to the blockchain, a selection unit for randomly selecting a plurality of nodes belonging to another blockchain is provided.

The selection unit may select a plurality of nodes belonging to the other blockchain by a selection function using at least a part of the hash value of the block generated immediately before in the blockchain to which the own node belongs as an input.

The selection function is a cryptographic hash function, and the selection unit extracts a plurality of IDs having a predetermined bit length from the output of the hash function, and a plurality of IDs belonging to the other blockchain corresponding to the IDs. You may select a node.

The selection unit may input a value obtained by concatenating a predetermined initial vector to the block generated immediately before the hash function.

The selection unit may update the initial vector if the consensus is not established.

The selection unit may determine the number of a plurality of nodes belonging to the other blockchain to be selected according to the number of nodes in the blockchain to which the own node belongs.

In the blockchain management method according to the present invention, a group consisting of a plurality of nodes belongs to a different blockchain from each other, and each node reaches a consensus for the block when the block of the blockchain to which the own node belongs is generated. As a participant, in addition to the node belonging to the blockchain, a plurality of nodes belonging to other blockchains are randomly selected.

In the blockchain management program according to the present invention, when a group consisting of a plurality of nodes belongs to a different blockchain from each other and a block of the blockchain to which the own node belongs is generated for each node, the consensus for the block is reached. As a participant, in addition to the node belonging to the blockchain, a plurality of nodes belonging to other blockchains are randomly selected.

According to the present invention, the reliability of each of the plurality of blockchains is improved.

It is a figure which shows the functional structure of the blockchain management system which concerns on embodiment. It is a figure which shows the structure of the block which concerns on embodiment. It is a figure which illustrates the node which participates in the process of the consensus which concerns on embodiment.

Hereinafter, an example of the embodiment of the present invention will be described.
FIG. 1 is a diagram showing a functional configuration of a node 10 (information processing device or information processing device group) belonging to each of a plurality of blockchains to be managed in the blockchain management system 1 according to the present embodiment.
A group consisting of a plurality of nodes 10 arranged in each organization that manages each of the blockchains belongs to different blockchains.
The node 10 includes a selection unit 11 and a generation unit 12.

When the selection unit 11 generates a block to be stored in the blockchain A to which the own node belongs, as a participant in the consensus for this block, in addition to the node 10 belonging to the blockchain A, another blockchain B, ... · · Randomly select a plurality of nodes 10 belonging to.
At this time, the selection unit 11 has a plurality of members belonging to other blockchains B, ... Select node 10 of.

The selection function may be a cryptographic hash function.
Specifically, the selection unit 11 extracts, for example, a plurality of IDs having a predetermined bit length from the output of the hash function, and selects a plurality of nodes 10 corresponding to these IDs.

For example, when the output of the hash function is 000101011, this output is divided into three (000/101/011), and each of them is converted into an integer to obtain three IDs (0, 5, 3). The ID is pre-allocated to the nodes 10 of the other blockchains B, ..., So that the node 10 of the blockchain A to which the own node 10 belongs is not selected.

The ID extraction method is not limited to this. For example, the extracted ID may be further divided into an ID for selecting the blockchain and an ID for selecting the node 10 in the blockchain. Further, for example, in order to avoid bias between blockchains, nodes 10 in the blockchain may be randomly selected by ID while selecting all blockchains in order.

At this time, the selection unit 11 inputs a value obtained by concatenating a predetermined initial vector to the block generated immediately before to the hash function.
Further, when the consensus is not established, the selection unit 11 updates the initial vector by incrementing or the like so that the same node 10 group is not extracted.

The selection unit 11 may determine the number of a plurality of nodes 10 to be selected according to the number of nodes 10 in the blockchain A to which the own node 10 belongs. For example, the block to which the own node 10 belongs to the consensus may be determined. The ratio of the number of participants from the chain A to the number of participants from other blockchains B, ... May be adjusted to the same level, or the number of all participants may be adjusted to a certain number.

The generation unit 12 generates a block in which one or a plurality of transaction data are recorded and stores it in the blockchain.
At this time, the generation unit 12 executes a consensus process in which the node 10 of the blockchain A to which the own node 10 belongs and the node 10 selected by the selection unit 11 participate. Only when a consensus is established, the generated block is stored in the blockchain A, and this block is distributed and shared to the node 10 belonging to the blockchain A.

For the consensus processing, a protocol based on a majority vote, such as PBFT (Practical Byzantine Fault Tolerance), may be adopted.
Participants in the selected consensus indicate their intention to agree or not, but the node 10 that refuses to participate may be automatically regarded as disagreement, for example.

FIG. 2 is a diagram showing a configuration of blocks stored in the block chain according to the present embodiment.
A plurality of transaction data recorded in each block of the blockchain is managed by a tree structure such as a Merkle hash tree, and the root hash of this tree structure is stored in the block.
Further, the block contains the hash value of the immediately preceding block and the initial vector used for inputting the selection function, and a digital signature of, for example, a representative or the like is given by combining these.

FIG. 3 is a diagram illustrating a node 10 participating in the consensus processing according to the present embodiment.
In this example, the five blockchains A to E are locally managed by different groups, and the consensus processing is executed in the blockchain A.

Here, it is assumed that the plurality of nodes 10 belonging to the blockchain A include a normal node 10 and an unauthorized node 10 which is an attacker. The smaller the blockchain, the higher the risk of collusion attacks by a small number of attackers. For example, in blockchain A, half of the total becomes an attacker, and a legitimate consensus process cannot be established.

Therefore, when the consensus processing is executed in the blockchain A, the participants are selected from the blockchains B to E in addition to the node 10 of the blockchain A. As a result, the population of participants becomes large, and the proportion of illegal nodes 10 included in the participants can be kept low.

Further, even if an attempt is made to send an unauthorized node 10 as a consensus participant from an external blockchain (for example, blockchain D), the external node 10 is randomly selected, so that an attacker can use a plurality of blockchains. A large number of collusions must be deployed across the board, making attacks difficult. For example, even if a large number of invalid nodes 10 exist in the blockchain D, these are not always selected, and further, the nodes 10 are also selected from the other blockchains B, C, and E, and as a result, the nodes 10 are selected. , The proportion of attackers in the total number of participants in the consensus is kept low.

According to the present embodiment, the blockchain management system 1 is configured by distributing a plurality of blockchains by a plurality of different groups. When generating a block in each blockchain, in addition to the node 10 belonging to the blockchain storing the block, a plurality of nodes 10 belonging to another blockchain are randomly selected as participants in the consensus.

Therefore, when the blockchain management system 1 processes consensus in each of the plurality of blockchains, the blockchain management system 1 adds nodes 10 belonging to other blockchains as participants and enlarges the population to counter the collusion attack. Increased resistance. As a result, the blockchain management system can improve the reliability of each of the plurality of blockchains.
In particular, when the scale of the local blockchain becomes smaller with an emphasis on efficiency or convenience, the risk of collusion attacks increases and reliability decreases because the number of nodes 10 belonging to this blockchain is small in the past. rice field. Since the blockchain management system 1 of the present embodiment can increase the number of nodes 10 participating in the consensus, the reliability can be improved regardless of the scale of the blockchain.

Further, since the blockchain management system 1 only adds participants to the consensus and does not change the consensus method adopted, it can be easily realized without modifying the existing platform.

In the blockchain management system 1, each node 10 selects a node 10 belonging to another blockchain by a selection function in which at least a part of the hash value of the immediately generated block in the blockchain to which the node 10 belongs is input. To participate in the consensus.
Therefore, since the selected node 10 is uniquely determined from the immediately preceding block, the validity of the process can be verified after the fact.

The blockchain management system 1 uses a cryptographic hash function as a selection function, and extracts a plurality of IDs having a predetermined bit length from the output of this hash function, thereby easily selecting a plurality of nodes 10 corresponding to the IDs. can.

The blockchain management system 1 can also input a value obtained by concatenating a predetermined initial vector to the block generated immediately before to the hash function. By preparing the initial vector for each application, the blockchain management system 1 can easily realize the selection process dedicated to the present embodiment in a verifiable manner.
Further, the blockchain management system 1 can avoid the situation where the same node 10 group is selected again by updating the initial vector when the consensus is not established.

The blockchain management system 1 determines the number of a plurality of nodes 10 to be selected from other blockchains according to the number of nodes 10 belonging to the blockchain, so that an appropriate number can be obtained regardless of the scale of the blockchain. Participants can reach consensus.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments. Moreover, the effects described in the above-described embodiments are merely a list of the most suitable effects resulting from the present invention, and the effects according to the present invention are not limited to those described in the embodiments.

The blockchain management method by the blockchain management system 1 is realized by software. When realized by software, the programs that make up this software are installed in the information processing device (computer). Further, these programs may be recorded on a removable medium such as a CD-ROM and distributed to the user, or may be distributed by being downloaded to the user's computer via a network. Further, these programs may be provided to the user's computer as a Web service via a network without being downloaded.

1 Blockchain management system 10 Nodes 11 Selection part 12 Generation part

Claims (7)

It is a blockchain management system that has multiple groups consisting of multiple nodes, each of which belongs to a different blockchain to be managed.
When each node generates a block of the blockchain to which its own node belongs, it was generated immediately before in the blockchain to which its own node belongs in addition to the node belonging to the blockchain as a participant in the consensus for the block. Multiples belonging to another blockchain that input a block into a hash function, input a part of the output of the hash function into a choice function whose output is uniquely determined for the input, and correspond to the output of the selection function. A blockchain management system with a selection section that randomly selects the nodes of. The selection function is a cryptographic hash function and is
The blockchain management according to claim 1, wherein the selection unit extracts a plurality of IDs having a predetermined bit length from the output of the hash function, and selects a plurality of nodes belonging to the other blockchain corresponding to the IDs. system. The blockchain management system according to claim 2, wherein the selection unit inputs a value obtained by concatenating a predetermined initial vector to the block generated immediately before to the hash function. The blockchain management system according to claim 3, wherein the selection unit updates the initial vector when the consensus is not established. The block according to any one of claims 1 to 4, wherein the selection unit determines the number of a plurality of nodes belonging to the other blockchain to be selected according to the number of nodes in the blockchain to which the own node belongs. Chain management system. Groups of multiple nodes belong to different blockchains,
When each node generates a block of the blockchain to which its own node belongs, it was generated immediately before in the blockchain to which its own node belongs in addition to the node belonging to the blockchain as a participant in the consensus for the block. Multiples belonging to another blockchain that input a block into a hash function, input a part of the output of the hash function into a choice function whose output is uniquely determined for the input, and correspond to the output of the selection function. A blockchain management method that randomly selects the nodes of. Groups of multiple nodes belong to different blockchains,
When generating a block of the blockchain to which the own node belongs to each node, as a participant in the consensus for the block, in addition to the node belonging to the blockchain, it was generated immediately before in the blockchain to which the own node belongs. Multiples belonging to another blockchain that input a block into a hash function, input a part of the output of the hash function into a choice function whose output is uniquely determined for the input, and correspond to the output of the selection function. A blockchain management program that allows you to randomly select a node in.

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