One article to understand the three types of blockchain: public chain, private chain and alliance chain
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Reprinted from: Observer Online www.blockob.com of block chain: the release Wen
Before introducing the public chain, private chain and alliance chain in detail, we have a general understanding of these concepts from the simplest literal meaning:
＊Public Blockchain: A public blockchain with read and write permissions open to everyone.
＊Private Blockchain: Private blockchain, with read and write permissions to control a certain node.
＊Consortium Blockchain: Consortium Blockchain, read and write permissions are open to the nodes joining the alliance.
The difference is in read and write permissions and the degree of decentralization. In general, the higher the degree of decentralization, the higher the credibility, and the slower the transaction speed.
▶ Public chain
Representative: Bitcoin blockchain, Ethereum smart contract
The verification nodes of the public chain are all over the world, and everyone participates in accounting and maintaining all transaction data on the blockchain.
The public chain can run stably, thanks to specific consensus mechanisms, such as the Bitcoin blockchain relies on Proof of Work (PoW), Ethereum currently relies on Proof of Stake (PoS), etc. Among them, Token (token, also known as "token" ) It can incentivize all participating nodes to be “willing to cooperate actively” to jointly maintain the security of data on the chain. Therefore, the public chain cannot operate without tokens.
1) All transaction data is open and transparent.
Although all nodes on the public chain are anonymous (more precisely, "non-real name") join the network, but any node can view the account balances and transaction activities of other nodes.
2) It cannot be tampered with.
The public chain is a highly decentralized distributed ledger, and it is almost impossible to tamper with transaction data unless the tamperer controls 51% of the computing power of the entire network and more than 500 million RMB in operating funds. Blockchain Watch (www.blockob.com) mentioned this in the article "What is Blockchain".
1) Low throughput (TPS).
High decentralization and low throughput are the dilemmas that public chains have to face. For example, the most mature public chain-the Bitcoin blockchain-can only process 7 transactions per second (according to the size of each transaction is 250 Bytes), the number of transactions that can be processed during the peak period is even lower.
2) The transaction speed is slow.
Low throughput will inevitably bring slow transaction speed. The bitcoin network is extremely congested, and sometimes a transaction can take several days to process, and there are hundreds of transfer fees.
▶ Private chain
Representative: Ant Financial
According to the "2017 Global Blockchain Enterprise Patent Ranking", Alibaba ranked first with 49 patents, and these patents are all from Ant Financial Technology Lab.
The read and write permissions of the private chain are in the hands of an organization or institution, and the organization determines the degree of openness of the blockchain chain according to its own needs; it is suitable for financial scenarios such as data management and auditing.
1) Faster transaction speed and lower transaction cost
Only a small number of nodes on the chain also have a high degree of trust, and each node is not required to verify a transaction. Therefore, compared with public chains that need to be verified by most nodes, private chains have faster transaction speeds and lower transaction costs.
2) Not easy to be maliciously attacked
Compared with a centralized database, the private chain can prevent a certain internal node from tampering with the data. Intentionally concealing or tampering with data is easy to find, and the source of the error can be traced when an error occurs.
3) To better protect the privacy of the organization itself, transaction data will not be disclosed to the entire network.
Blockchain is the best solution for building social trust, and "decentralization" is the core value of blockchain. However, the private chain controlled by an organization or institution is different from the concept of "decentralization". If it is too centralized, it is not much different from other centralized databases.
▶ Alliance chain
Representative: Hyperledger (Hyperledger)
Super ledger is based on transparent and decentralized distributed ledger technology. Members of the alliance (including Intel, Accenture, etc.) work together to create an open standard for distributed ledger to realize value exchange. It is very suitable for the financial industry, as well as energy, Insurance, Internet of Things and other industries.
The alliance chain is jointly maintained by the member nodes in the alliance, and the nodes can only join the alliance network after being authorized.
The alliance chain is a kind of private chain, but the degree of privacy is different, and its permission design requirements are more complicated than the private chain; but the alliance chain is more credible than the pure private chain.
to sum up:
In the landing scenarios that have high requirements for credibility and security, but are not demanding for transaction speed, the public chain has more development potential.
For landing applications that pay more attention to privacy protection, transaction speed, and internal supervision, it is more appropriate to develop a private chain or alliance chain.
 Blockchain chooses only two of the three aspects of high efficiency, decentralization and security. This is the “impossible triangle” paradox of blockchain. Therefore, no matter whether it is a public chain, a private chain, or an alliance chain, there will be one or the other deficiencies, or-they have no absolute advantages and disadvantages, and different blockchain types should be viewed according to specific landing applications.