北京大学 区块链,北京大学区块链专业课程表

北京大学区块链专业课程表将带来更多的学习机会，让我们更好的了解区块链技术。比特币是一种去中心化的数字货币，它采用区块链技术作为其底层技术。比特币利用区块链技术实现了去中心化的数字货币交易，让用户可以安全、快捷、便捷的进行网络交易。比特币的出现，让区块链技术受到了极大的关注，也推动了区块链技术的发展。

比特币的出现只是区块链技术的一部分，智能合约也是区块链技术的重要组成部分。智能合约是一种可以在区块链上实现的自动执行的合约，它可以用来实现自动执行的交易，而无需人为干预。智能合约可以替代传统的合约，让交易更加安全、可靠、便捷。

区块链技术在不断发展，去中心化应用也在不断增多。去中心化应用是指利用区块链技术实现的应用，它可以实现去中心化的交易，让用户可以安全、快捷、便捷的进行网络交易。去中心化应用不仅可以用于金融领域，还可以用于游戏、医疗、教育等各个领域，推动了区块链技术的发展。

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Ⅰ Beijing Java Course Shares the Consensus Algorithm in Blockchain Technology

We have shared with you many times some explanations and analysis of knowledge points about blockchain technology. . Today, in the Beijing Java course, we will learn about some basic definitions and characteristics of consensus algorithms in blockchain technology.

A brief look at the blockchain

The chain in our general ideology is an iron chain, made of iron. One link after another. Figuratively, the blockchain can also be understood in this way, except that it is not made of iron, but connected by blocks with a certain data structure. This is a simple prototype

Popular explanation of consensus

The so-called consensus, in layman’s terms, means that we all agree on the understanding of something. For example, we have daily meetings to discuss issues, or we can judge whether an animal is a cat. After looking at it with the naked eye, we feel it looks like a cat. If it meets the characteristics of a cat, then we think it is a cat. Consensus is a rule.

Continue to use our meeting example. Participants in the meeting discuss and solve problems through meetings.

Compared with the blockchain, miners participating in mining use a certain consensus method (algorithm) to make their own ledger consistent with the ledgers of other nodes. The deeper meaning of keeping the ledger consistent is to keep the block information in the chain consistent.

Why is consensus needed? Is it possible to not need it? Of course not. Without the rules of consensus in life, everything will be chaotic. The blockchain loses consensus rules, and each node does its own thing, losing its consistent meaning.

The corresponding relationship between these two examples is as follows:

Meeting people = mining miners

Meeting = consensus method (algorithm)

Talk about solving problems = make your own ledger consistent with the ledgers of other nodes

If you don’t understand the concept of a node, please first understand it as a miner. A node contains many roles, and miners are one of them.

Consensus algorithm

Currently in the blockchain, nodes allow their own ledgers to match those of other nodes. There are several consensus methods (algorithms) that maintain consistency:

PoW, represented by Bitcoin (BTC)

Disadvantages:

The emergence of mining pools violates the original intention of decentralization to a certain extent, and also makes 51% attacks possible, affecting its security.

There is a huge waste of computing power. Look at the mining pool that consumes a lot of electricity resources. As the difficulty increases, not enough is mined to pay the electricity bill

PoS, represented by Ethereum (ETH), transitioning from PoW to PoS

Disadvantages:

The cost of saboteurs attacking the network is very low, and they can compete if they own tokens

In addition, nodes with a large number of tokens can obtain accounting rights. The probability will be greater, which will make the network consensus dominated by a few wealthy accounts, thus losing fairness.

II What is blockchain? Explanation of blockchain technology

Blockchain is distributed data storage, point-to-point transmission, consensus mechanism, encryption algorithm, etc. New application models of computer technology. Blockchain is an important concept of Bitcoin. It is essentially a decentralized database.

At the same time, as the underlying technology of Bitcoin, it is a series of data blocks generated using cryptographic methods. Each data block contains a batch of Bitcoin network transaction information, which is used to verify its Validity of information (anti-counterfeiting) and generation of the next block.

The blockchain is a public data list, and each record in it is called a block. These blocks are connected together like a chain to form a blockchain. Just like an idiom solitaire, there must be some connection between adjacent words to form a word chain. The same is true for blockchain, but the connection between blocks is much more complex.

(2) Extended reading on blockchain technology explanation published by Peking University

Blockchain technology innovation does not mean speculating on virtual currencies, and that kind of behavior should be prevented Use blockchain to issue virtual currencies and speculate on air coins. At the same time, we should also note that blockchain is still in its early development stage and needs further development and improvement in terms of security, standards, supervision, etc.

The general direction is not wrong, but it is necessary to avoid rushing in and duplicating construction, and to open up the imagination space of the blockchain in orderly competition. China has a good foundation in the field of blockchain. Some large Internet companies have already laid out their plans. The talent pool is relatively sufficient and the application scenarios are rich. It is fully qualified to achieve a leading position in this new track.

From a larger perspective, human beings can develop civilization because they have achieved effective cooperation among large-scale groups of people. The "invisible hand" explained by Adam Smith also realizes the division of labor and cooperation in human society through the market mechanism.

From this perspective, blockchain has greatly expanded the breadth and depth of human trust and collaboration. Perhaps, blockchain is not only the next generation of Internet technology, but also the next generation of cooperation mechanisms and organizational forms.

Ⅲ Easy-to-understand explanation of blockchain

The popular explanation of blockchain technology is as follows:

To put it simply: blockchain is the use of a package of existing A new generation of network system formed using advanced network technology. This network system has a new structure, a new mechanism, and unprecedented new value. Five major technologies or innovations were specifically used: encryption technology, P2P network technology, distributed storage technology, consensus mechanism, and smart contracts.

Essentially: it is a shared database, and the data or information stored in it has the characteristics of "unforgeable", "full traces", "traceable", "open and transparent" and "collectively maintained". ” and other characteristics. Based on these characteristics, blockchain technology has laid a solid foundation for "trust and sales" and created a reliable "cooperation" mechanism. Yunchun has broad application prospects.

2. Openness.

In addition to encrypting the private information of all parties to the transaction, the blockchain data is open to everyone and provides a flexible script code system. The entire system information is highly transparent and within the rules specified by the system. Nodes cannot deceive each other.

3. Autonomy.

Consensus technology, smart contracts.

IV Popular explanation of blockchain technology

Blockchain is a new application model of computer technology such as distributed data storage, point-to-point transmission, consensus mechanism, and encryption algorithm. Blockchain is an important concept of Bitcoin, which is essentially a decentralized database. At the same time, as the underlying technology of Bitcoin, it is a series of data blocks generated by cryptographic technology. Each data block contains a batch of Bitcoin network transaction information, which is used to verify the validity of its information (anti-counterfeiting) and generate the next data block.
First of all, it is a special distributed database that is essentially readable and writable. The unit then entered into the database is a "block", which is decentralized.
It doesn’t seem to be easy to understand when explained in this way, so let’s give a simple example.

When we shop on Taobao, because neither the buyer nor the seller knows each other's credit, we need to introduce a third-party platform - Alipay. Alipay is a trustworthy platform. The buyer first gives money to Alipay. After the seller delivers the goods, the buyer receives the money and notifies Alipay, who then lends the money to the seller. In this way, there is no need to worry about credit issues in the transaction.

IV Peking University Jade Bird Design Training: The Element Architecture of Blockchain Technology

With the continuous development of the Internet, more and more people have learned about some of the characteristics and uses of blockchain technology. situation, today we will introduce what some elements of the blockchain are in Zhengzhou.
Composition of Blockchain Blockchain consists of blocks and chains.
Each block contains three elements: data, hash value, and the hash value of the previous block.
The first element of the block is data.
The data stored in the block is related to the type of blockchain.
For example, blocks in the Bitcoin blockchain save relevant transaction information, including sellers, buyers, and the amount of Bitcoin traded.
The second element of the block is the hash value.
Each block contains a hash value, which is used to identify a block and all the content it contains.
Once a block is created, its hash value is calculated accordingly.
Change blockSomething in it will cause the hash value to change.
So in other words: hashes are helpful when you want to detect changes to content in a block.
If the fingerprint of a block changes, it is no longer the same block as before.
The third element of the block is the hash of the previous block.
This element allows links to be formed between blocks and makes the blockchain very secure.
For example, suppose we have a blockchain containing 3 blocks.
Each block contains its own hash value and the hash value of the previous block.
Block No. 3 points to Block No. 2, and Block No. 2 points to Block No. 1.
But block No. 1 is a bit special, it cannot point to the previous block because it is the first block.
We call block 1 the genesis block.
So, now let's assume you tampered with the second block.
This will cause the hash value of the second block to change, so the data stored in block No. 3 will be wrong and illegal.
Once the data stored in block 3 is illegal, the following blocks must also be illegal.
So if a person wants to tamper with any block in the blockchain, it must modify this block and all blocks after this block.
This will be a heavy task.
Blockchain's Proof of Work However, the method of using hash values ​​alone is not enough to prevent users from tampering with blocks.
Because today's computer computing speed is powerful enough and can calculate thousands of hash values ​​per second.
java course http://www.kmbdqn.cn/ suggests that you can completely tamper with a block and recalculate the hash values ​​of other blocks, thus making your block legal again.

VI How to understand the decentralization of blockchain technology

On the Internet, the most typical example of centralization is the portal website, which connects the Internet to All the information on the Internet is collected on its own platform, forming a central node, and then many branches extend from this node, but usually only one node is making decisions. Jinwowo Network Technology analysis believes that the characteristics leading to centralization are:

1. The central node controls the distributed node information

2. The branch nodes do not control other node information (centralization , the transaction is not public).

And the pain point of centralization is that system security depends on the security of the central node, and distributed nodes have no control over this.