According to the access mechanism, blockchain can be divided into three basic types: Public Block Chain, Consortium Block Chain and Private Block Chain.

(1) Public chain

The public blockchain is the earliest blockchain. As the name suggests, it is public, open, and the most widely used blockchain. The public chain is the blockchain with the highest degree of openness and the highest degree of decentralization. Its data update, storage and operation do not depend on a centralized server, but on every node on the network, which means The data on the public chain is jointly recorded and maintained by thousands of network nodes on the global Internet, and no one can tamper with the data.

In the public chain, every participant has the right to access the distributed ledger, every record is not monitored and regulated by any organization, program development organizations and personnel have no right to interfere with users, the blockchain can protect its users, and the public chain relies on encryption technology To ensure its security, it is generally suitable for B2C, C2C or C2B application scenarios such as cryptocurrency, bulk-oriented e-commerce, and Internet finance.

(2) Alliance chain

A consortium chain refers to a blockchain whose consensus process is controlled by pre-selected nodes. Multiple pre-selected nodes are designated as bookkeepers within a group. The generation of each block is jointly determined by all pre-selected nodes (pre-selected nodes participate in the consensus process.) ), other access nodes can participate in transactions, but do not ask about the bookkeeping process (essentially, it is still managed bookkeeping, but it becomes distributed bookkeeping), and anyone else can make limited queries through the open API of the blockchain.

The alliance chain is limited to the participation of alliance members, and the read and write permissions on the blockchain are formulated according to the rules of the alliance. The alliance chain network is jointly maintained by member institutions, and network access is generally accessed through the gateway nodes of member institutions. The alliance chain platform should provide security management functions such as member management, authentication, authorization, monitoring, and auditing. A consortium chain is a blockchain that requires registration and permission, and its consensus process is controlled by pre-selected nodes. Generally speaking, it is suitable for B2B scenarios such as inter-institutional transactions, settlement or clearing. For example, the system of payment, settlement and settlement between banks can use the form of alliance chain to use the gateway nodes of each bank as the accounting node.

(3) Private chain

The private chain is not open to the outside world, and only authorized nodes can participate and view the blockchain type of data. The typical application of private chain is the blockchain developed by the central bank to issue central bank digital currency. This chain can only be recorded by the central bank, and it is impossible for individuals to participate. There are also some large companies that are working on private chains, such as Alibaba, Baidu, JD.com, etc. They mainly focus on the role of blockchain in data security, supply chain and other industry pain points.

Different from the complete decentralization of the public chain, the private chain is a blockchain with certain centralized control. The read and write permissions of the private chain are controlled by an organization and institution. Read permissions are either open to the outside world, or restricted to any degree. Relevant applications can include database management, auditing or even a company. Conservative giants (traditional finance) all want to experiment with private blockchains, while the applications of public chains such as Bitcoin have been industrialized, and the application products of private chains are still being explored.