Chapter 2 Core Technology Concepts

1. Definition and Principle

1. definition

In the definition given on Wikipedia, the blockchain is analogous to a distributed database technology. By maintaining the chain structure of data blocks, it can maintain continuously growing and tamper-resistant data records.

2. Fundamental

First assume that there is a distributed ledger of data records, which only allows additions and does not allow deletions. The basic structure of the bottom layer of the ledger is a linear linked list, which is also the source of its name "blockchain". The linked list consists of a series of "blocks" (as shown in the figure below), and subsequent blocks record the hash value (pre hash) of the preceding block. For new data to be added, it must be placed in a new block.

3. Working process (take Bitcoin as an example)

a. The Bitcoin client initiates a transaction

b. After the node in the network receives it, it starts to calculate, trying to find a nonce string (random string), so that the hash result of the candidate block satisfies a certain condition (such as less than a certain value).

c. After the nonce string is found, it will be broadcast. After other nodes receive it, they will verify the legitimacy of the string. If it is found that it does meet the agreed conditions, it will recognize the block as a legal new block and add it to itself maintained on the blockchain. When a majority of nodes add a block to the blockchain structure they maintain, the block is accepted by the network, and the transactions included in the block are confirmed.

 

The above process of calculating and finding the nonce string is called Proof of Work (PoW). At present, there is no known fast heuristic algorithm to make the hash result meet certain conditions, and only tentative brute force calculations can be performed. The more attempts (and the greater the workload), the greater the calculated probability.

 

2. Deepening and classification of technology

1. The evolution of blockchain

2. Blockchain and Distributed Accounting

Compared with traditional accounting technology, distributed ledgers based on blockchain should include the following features:

a. To maintain a growing chain, only records can be added, and records that have occurred cannot be tampered with;

b. Decentralization, or multi-centralization, can reach consensus without centralized control, and use distributed as much as possible for implementation;

c. Use the cryptographic mechanism to ensure that transactions cannot be denied and destroyed, and try to protect the privacy of user information and records.

3. Classification

According to the different participants, it can be divided into public (public) chain, consortium (consortium) chain and private (private) chain.

 

3. Key Issues and Challenges

1. Non-repudiation and privacy protection
2. Distributed consensus
3. Transaction performance
4. Extensibility
5. Security
6. Databases and Storage Systems
7. Integration and Operations

 

四、趋势与展望

 

五、认识上的误区

1. 区块链不等于比特币
2. 区块链不等于数据库
3. 区块链并非一门万能的颠覆性技术