区块链 图解,区块链图文解释

区块链是一种分布式数据库技术，它允许用户以安全可靠的方式来存储和交换信息。它是一种分布式账本技术，可以记录所有交易的历史，而不需要任何中央机构来管理。

区块链的图文解释是，它是一种以分布式的方式来存储和交换数据的技术，它通过使用密码学和分布式记账技术来确保数据的安全性、完整性和可靠性。它利用一系列的数据块（称为“区块”）来存储信息，这些数据块被分布在多个节点上，每个节点都可以查看和验证数据的完整性。

区块链的优势在于，它可以提供安全性和可靠性，因为它不受任何中央机构的控制，而且可以确保数据的完整性和安全性。此外，它还可以提供高度可审计性，因为所有的交易都被记录在区块链上，任何人都可以查看并验证所有的交易历史。

区块链技术的应用非常广泛，它可以用来处理货币交易、智能合约、分布式计算、供应链管理等等。例如，它可以用来记录金融交易，以确保交易的安全性，以及可以用来跟踪物流信息，以确保供应链的完整性。

总之，区块链技术可以为用户提供安全可靠的数据存储和交换方式，它可以用来处理复杂的金融交易和供应链管理，从而提高数据的安全性和可靠性。

Ⅰ Comic illustration: What is blockchain

Comic illustration: What is blockchain

What is blockchain?
Blockchain, English Blockchain, is essentially a decentralized distributed database. Anyone can become a node of this huge network as long as they set up their own server and connect to the blockchain network.
Since the blockchain is essentially a database, what exactly is stored in it? Let’s take a look at the basic unit of blockchain: Block.
A block is divided into two parts:
1. Block header
The block header stores the header information of the block, including the hash value (PreHash) of the previous block. The hash value of the block body (Hash), the timestamp (TimeStamp), etc.
2. Block body
The block body stores the detailed data (Data) of this block. This data contains several rows of records, which can be transaction information or some other information.
What does the hash value just mentioned mean?
Everyone must have heard of MD5. MD5 is a typical hash algorithm that can convert a string of plaintext of any length into a string of fixed length (128 bits). This string is the hash value.
In our blockchain, a more complex hash algorithm called SHA256 is used. After a series of complex calculations, the latest data information (such as transaction records) will eventually be converted into a 256-bit hash value string through this hash algorithm, which is the Hash in the block header. The format is as follows:

Blocks and Hash have a one-to-one correspondence, and Hash can be regarded as the unique identifier of the block.
How are different blocks related to each other? Rely on Hash and PreHash to associate. The PreHash value of each block is equal to the Hash value of the previous block.
Why do we need to calculate the hash value of the block?
Since the blockchain is a chain structure, there must be a head node (the first block) and a tail node (the last block) of the chain. Once someone calculates the hash value of the latest data in the blockchain, which is equivalent to packaging the latest transaction records, a new block will be created and connected to the end of the blockchain.
The Hash of the new block header is the hash value just calculated, and the PreHash is equal to the Hash of the previous block. The data in the block body stores the transaction records before packaging, and this part of the data information has become unmodifiable.
This process of calculating Hash values ​​and creating new blocks is called mining.
The server used for massive calculations is called a mining machine.
The workers who operate calculations are called miners.
Compute HashWhat’s so hard about it? Let’s give the most superficial explanation. The formula for calculating the hash value is as follows:
Hash = SHA-256 (Hash of the last block + basic information of the new block + transaction record information + random number)
Among them, the transaction record information is also a string of hash values, and its calculation involves a data structure Merkle Tree. Interested friends can check the relevant information, we will not introduce it for now.
The key computational difficulty here lies in the generation of random numbers. In order to increase the difficulty of Hash calculation, the wretched inventor of the blockchain requires that the first 72 bits of the Hash result must be 0. This probability is too small.
Since (the Hash of the last block + the basic information of the new block + the transaction record information) is fixed, whether the Hash that meets the requirements can be obtained depends entirely on the value of the random number. Miners must go through massive calculations and repeatedly generate random numbers in a general attempt to "get lucky" before they can get the correct Hash and successfully mine.
At the same time, the block header also contains a dynamic difficulty coefficient. When the world's hardware computing power becomes faster and faster, the difficulty coefficient of the blockchain will also increase, making the entire network capable of completing the task every 10 minutes on average. A new block is generated.
Friends, do you understand how difficult mining is? It should be added that different blockchain applications are different in details. The mining rules described here take Bitcoin as an example.
Applications of Blockchain

The concept of Bitcoin (BitCoin) was first proposed by Satoshi Nakamoto in 2008, and then based on this idea, open source software and P2P built on it were designed and released. network. Bitcoin is a P2P form of digital currency. Peer-to-peer transmission means a decentralized payment system.
What is a P2P network?
Traditional currencies are uniformly issued by the central bank, and all personal savings are uniformly managed by banks. This is a typical centralized system.
Bitcoin is deployed on a decentralized network composed of many peer nodes around the world. Every node is qualified to record and issue this digital currency.
As for the underlying data storage of Bitcoin, it is based on blockchain technology. Each transaction in Bitcoin corresponds to a row in the block data. A simple diagram is as follows:
Each row of the transaction record contains a timestamp, transaction details, and digital signature.
The table is only for ease of understanding. The actual stored transaction details are anonymous, and only the wallet addresses of the payer and payee are recorded.
As for digital signatures, they can be understood as anti-counterfeiting marks for each single transaction, generated by an asymmetric encryption algorithm.
Let’s talk about the rewards of Bitcoin miners:
The Bitcoin protocol stipulates that miners who mine new blocks will receiveThe reward has been 50 Bitcoins since 2008, and has been halved every 4 years. Currently, it is 12.5 Bitcoins in 2018. The new Bitcoins in circulation are all born in this way. No wonder everyone is so eager to mine Bitcoins!
Advantages and Disadvantages of Blockchain
Advantages of Blockchain:
1. Decentralization
Blockchain does not rely on a central node. The data of the entire system is All peer nodes in the entire network are jointly maintained and can store and verify data. In this way, unless the attacker hacks more than half of the nodes in the entire network, the entire system will not be destroyed.
2. Information cannot be tampered
The data in the block cannot be tampered with. Once the data is tampered with even a little bit, the hash value corresponding to the entire block will change accordingly, and it will no longer be a valid hash value, and the subsequent linked blocks will also be broken.
Disadvantages of blockchain:
1. Excessive consumption of energy
To generate a new block, a large amount of server resources must be used to perform a large number of unnecessary trial calculations, which seriously consumes electricity.
2. Network delay of information
Take Bitcoin as an example. Any transaction data needs to be synchronized to all other nodes. The synchronization process will inevitably be affected by network transmission delay, resulting in a long time consuming.
A few additional points:
1. Part of the content of this comic refers to Ruan Yifeng’s blog post "Blockchain Introductory Tutorial". I would like to thank this great master for his popular science.
2. Due to limited space, the knowledge about Merkle Tree and asymmetric encryption has not been discussed in detail for the time being. Interested friends can check the information for further study.

Ⅱ Tutorial for getting started with blockchain

However, there are very few simple and easy-to-understand introductory articles. What exactly blockchain is and what makes it special is rarely explained.
Next, I will try to write a best-understood blockchain tutorial. After all, it is not difficult. The core concept is very simple and can be explained clearly in a few sentences. I hope that after reading this article, you will not only understand the blockchain, but also understand what mining is, why mining is getting more and more difficult, and other issues.
It should be noted that I am not an expert in this area. Although I have been paying attention to it for a long time, my detailed understanding of blockchain started at the beginning of this year. You are welcome to correct any errors or inaccuracies in the article.
1. The essence of blockchain
What is blockchain? In a word, it is a special distributed database.
First of all, the main function of blockchain is to store information. Any information that needs to be saved can be written to the blockchain and read from it, so it is a database.
Secondly, anyone can set up a server, join the blockchain network, and become a node. In the world of blockchain, there is no central node. Every node is equal and stores the entire database. You can write/read to any nodeFetch data, because all nodes will eventually be synchronized to ensure that the blockchain is consistent.
2. The biggest features of blockchain
Distributed databases are not a new invention, and there have been such products on the market for a long time. However, blockchain has a revolutionary feature.
Blockchain has no administrator, it is completely centerless. Other databases have administrators, but blockchain does not. If one wanted to add auditing to the blockchain, it would not be possible because it is designed to prevent the emergence of a central authority.
It is precisely because it is unmanageable that blockchain can be uncontrollable. Otherwise, once big companies and large groups control the management, they will control the entire platform, and other users will have to take orders from them.
However, without an administrator, everyone can write data into it. How can we ensure that the data is trustworthy? What if it is modified by a bad person? Please read on, this is the wonderful thing about blockchain place.
3. Block
Blockchain is composed of blocks. Blocks are much like database records. Every time data is written, a block is created.
Each block contains two parts.
Head: records the characteristic values ​​of the current block
Body: actual data
The block header contains multiple characteristic values ​​of the current block.
Generation time
Hash of the actual data (i.e. block body)
Hash of the previous block
...
Here, you need to understand what a hash is , which is necessary to understand blockchain.
The so-called hashing means that the computer can calculate a characteristic value of the same length for any content. The hash length of the blockchain is 256 bits, which means that no matter what the original content is, a 256-bit binary number will be calculated in the end. And it can be guaranteed that as long as the original content is different, the corresponding hash must be different.
For example, the hash of the string 123 is (hexadecimal), which is 256 bits when converted to binary, and only 123 can get this hash. (Theoretically, it is possible for other strings to get this hash, but the probability is extremely low and can be approximated as impossible.)
Therefore, there are two important inferences.
Corollary 1: The hash of each block is different, and the block can be identified by the hash.
Corollary 2: If the content of the block changes, its hash will definitely change.
4. The non-modifiable nature of Hash
Blocks and hashes have a one-to-one correspondence, and the hash of each block is calculated based on the block header (Head). That is to say, the characteristic values ​​​​of the block header are connected together in order to form a very long string, and then the hash is calculated on this string.
Hash = SHA256 (block header)
The above is the calculation formula of block hash. SHA256 is the hash algorithm of the blockchain. Note that this formula only contains the block header, not the block body, that isIt is said that the hash is uniquely determined by the block header. As mentioned earlier, the block header contains a lot of content, including the hash of the current block body and the hash of the previous block. This means that if the content of the current block body changes, or the hash of the previous block changes, it will definitely cause the hash of the current block to change.
This point has great significance for blockchain. If someone modifies a block, the hash of the block changes. In order for subsequent blocks to still be connected to it (because the next block contains the hash of the previous block), the person must modify all subsequent blocks in sequence, otherwise the modified block will be removed from the blockchain . Due to the reasons mentioned later, hash calculation is very time-consuming, and it is almost impossible to modify multiple blocks in a short period of time, unless someone controls more than 51% of the computing power of the entire network.
It is through this linkage mechanism that the blockchain ensures its own reliability. Once the data is written, it cannot be tampered with. This is just like history, what happened happened, and it can’t be changed from now on.
Each block is connected to the previous block, which is where the name blockchain comes from.
5. Mining
Since synchronization between nodes must be ensured, the adding speed of new blocks cannot be too fast. Just imagine, you have just synchronized a block and are preparing to generate the next block based on it, but at this time, another node generates a new block, and you have to give up half of the calculations and synchronize again. Because each block can only be followed by one block, you can only generate the next block after the latest block. So, you have no choice but to sync as soon as you hear the signal.
So, the inventor of the blockchain, Satoshi Nakamoto (this is a pseudonym, and his true identity is still unknown) deliberately made it difficult to add new blocks. His design is that on average, the entire network can generate a new block every 10 minutes, which is only six per hour.
This output speed is not achieved through commands, but by deliberately setting up massive calculations. In other words, only through an extremely large amount of calculations can the effective hash of the current block be obtained and the new block added to the blockchain. Because the amount of calculation is too large, it cannot be done quickly.
This process is called mining, because the difficulty of calculating a valid hash is like finding a grain of sand that meets the conditions among the sand in the world. The machine that calculates hashes is called a mining machine, and the person who operates the mining machine is called a miner.
6. Difficulty coefficient
After reading this, you may have a question. People say that mining is difficult, but isn’t mining just about using a computer to calculate a hash? This is the strength of computers. How could it be? It becomes very difficult, why can’t it be calculated?
It turns out that not just any hash can be used, only hashes that meet the conditions will be accepted by the blockchain. This condition is particularly harsh, causing most hashes to fail to meet the requirements and must be recalculated.
It turns out that the block header contains a difficulty coefficient (difficulty), which determines the difficulty of calculating the hash. For example, the 100,000th blockThe difficulty coefficient is 14484.16236122.
The blockchain protocol stipulates that the target value (target) can be obtained by dividing the difficulty coefficient by a constant. Obviously, the greater the difficulty coefficient, the smaller the target value.
The validity of the hash is closely related to the target value. Only hashes smaller than the target value are valid, otherwise the hash is invalid and must be recalculated. Since the target value is very small, the chance that the hash is smaller than this value is extremely slim, and it may be calculated 1 billion times before it is considered a hit. This is the fundamental reason why mining is so slow.
As mentioned earlier, the hash of the current block is uniquely determined by the block header. If the hash of the same block needs to be calculated repeatedly, it means that the block header must keep changing, otherwise it is impossible to calculate different hashes. All feature values ​​in the block header are fixed. In order to make the block header change, Satoshi Nakamoto deliberately added a random item called Nonce.
Nonce is a random value. The role of the miner is actually to guess the value of Nonce so that the hash of the block header can be smaller than the target value so that it can be written to the blockchain. Nonce is very difficult to guess. At present, we can only use trial and error one by one through exhaustive methods. According to the protocol, Nonce is a 32-bit binary value, which can reach a maximum of 2.147 billion. The Nonce value of the 100,000th block is 274148111. It can be understood that the miner started from 0 and calculated 274 million times before obtaining a valid Nonce value so that the calculated hash can meet the conditions.
If you are lucky, you may find Nonce in a while. If you are unlucky, you may have calculated it 2.147 billion times without finding the Nonce, that is, it is impossible to calculate a hash that meets the conditions for the current block body. At this time, the protocol allows miners to change the block body and start a new calculation.
7. Dynamic adjustment of difficulty coefficient
As mentioned in the previous section, mining is random, and there is no guarantee that a block will be produced in exactly ten minutes. Sometimes it can be calculated in one minute, and sometimes it may take several hours. No result. Overall, with the improvement of hardware equipment and the increase in the number of mining machines, the computing speed will definitely become faster and faster.
In order to keep the output rate constant at ten minutes, Satoshi Nakamoto also designed a dynamic adjustment mechanism for the difficulty coefficient. He stipulated that the difficulty factor should be adjusted every two weeks (2016 blocks). If the average block generation speed in these two weeks is 9 minutes, it means that it is 10% faster than the legal speed, so the next difficulty factor will be increased by 10%; if the average block generation speed is 11 minutes, it means It is 10% slower than the legal speed, so the difficulty factor of the next step must be lowered by 10%.
The difficulty coefficient is adjusted higher and higher (the target value is getting smaller and smaller), which makes mining more and more difficult.
8. Forks of the blockchain
Even if the blockchain is reliable, there is still an unresolved problem: if two people write data to the blockchain at the same time, that is to say, two people write data to the blockchain at the same time. block join as itThey are all connected to the previous block, forming a fork. Which block should be adopted at this time?
The current rule is that new nodes always adopt the longest blockchain. If there is a fork in the blockchain, it will look at which branch is behind the fork to reach 6 new blocks first (called six confirmations). Based on a block calculation of 10 minutes, it can be confirmed in one hour.
Since the generation speed of new blocks is determined by computing power, this rule means that the branch with the most computing power is the authentic blockchain.
9. Summary
Blockchain, as an unmanaged distributed database, has been running for 8 years since 2009 without major problems. This proves it works.
However, in order to ensure the reliability of data, blockchain also has its own price. The first is efficiency. You have to wait at least ten minutes to write data to the blockchain. All nodes synchronize the data, which requires more time. The second is energy consumption. The generation of blocks requires miners to perform countless meaningless calculations. This is Very energy consuming.
Therefore, the applicable scenarios of blockchain are actually very limited.
There is no management authority that all members trust
The written data does not require real-time use
The benefits of mining can make up for its own costs
If the above conditions cannot be met, then the traditional database is Better solution.
Currently, the largest application scenario (and possibly the only application scenario) of blockchain is the cryptocurrency represented by Bitcoin.

Ⅲ What is the principle of blockchain

When I saw some answers arguing about the definition of blockchain, I suddenly realized that my answer to explaining the principle had always been For those who are interested in Bitcoin, the industry does not have a particularly clear and unique answer to the definition of blockchain. Here are the characteristics that a "blockchain" should have that I have summarized based on the papers I have read:

1. A data structure in the form of a "hash chain" (explained below) is used to save basic data

2. There are multiple nodes participating in system operation (distributed )

3. Reach a consensus on the consistency of basic data through a certain protocol or algorithm (consensus protocol/algorithm).

Since Bitcoin is currently one of the most typical and influential applications of blockchain, after understanding how Bitcoin uses blockchain, you can then understand other various forms of blockchain applications. It will be much easier.

IV Briefly explain what blockchain is

Blockchain is a term in the field of information technology. In essence, it is a shared database, and the data or information stored in it has the characteristics of "unforgeable", "full traces left", "traceable", "open and transparent" and "collectively maintained". Based on these characteristics, blockchain technology has laid a solid foundation of "trust" and created a reliable "cooperation" mechanism, which has broad application prospects.

January 10, 2019The Cyberspace Administration of China issued the "Blockchain Information Service Management Regulations". On October 24, 2019, during the 18th collective study session of the Political Bureau of the CPC Central Committee, General Secretary Xi Jinping emphasized that “blockchain should be used as an important breakthrough for independent innovation of core technologies” and “accelerate the development of blockchain technology and industrial innovation.” . "Blockchain" has entered the public eye and become the focus of society.

On December 2, 2019, the word was selected into the top ten buzzwords of 2019 by "Biwenqiezi".

(4) One-minute illustrated blockchain extended reading:

Blockchain financial application:

Since 2016, Major financial giants have also taken notice and launched blockchain innovation projects one after another to explore the possibility of applying blockchain technology in various financial scenarios. In particular, Puyin Group took the lead in pioneering the “blockchain+” standard digital currency.

The standard digital currency is an asset that has been identified, evaluated, confirmed, insured, etc. by a third-party organization and written into the blockchain through rigorous digital algorithms to form a standard correspondence between the asset and the digital currency. relationship, called a standard digital currency.

In order to realize the great leap forward development of blockchain finance, in order to promote the new development of China's economy, accelerate the circulation of global assets, and realize the dream of rejuvenation that generations of people have been striving for, Puyin Group will Puyin Blockchain Finance Guiyang Strategy Release Ceremony was held in Guizhou on the 9th;

At the meeting, the digital circulation of assets through blockchain, the blockchain financial transaction model, and the relationship between blockchain services and blockchain services will be discussed. The application of social public industries will be discussed. This conference will mark the beginning of the application of blockchain finance and the transformation and development of a new financial ecosystem.

IV What are the development prospects of digital currency? Can it be regarded as a scam?

Due to the continued popularity of Bitcoin, people have begun to pay close attention to this digital currency. However, People from all walks of life are paying more attention to the technical architecture behind Bitcoin - blockchain technology. This technology is considered by many institutions to be the most likely to trigger the fifth round of technological revolution after steam engines, electricity, information and Internet technologies. Core Technology.

Bitcoin may fall, but the long-term direction of digital currencies must be to rise, and it will rise particularly violently. In 2017, the total market value of global digital currencies was only US$647 billion, less than 10% of the global physical gold market value, and accounted for less than 0.01% of the total national stock value. The launch of AAC comes at the right time, and miners know that the earlier they enter, the more tokens they can mine and the more profits they can earn. The birth of Acute Angle Cloud will bring generous returns to its partners.

2017 can be considered the first year of blockchain technology, and 2018 is likely to be the year of the explosion of blockchain technology. Acute Angle Cloud is likely to usher in the fast train of blockchain technology. explosive growthLong, the Acute Angle PC released at CES2018 is likely to become another blockbuster product in the blockchain.

VI What is the blockchain that is impacting the financial industry?

The principle of blockchain has been talked about by many people recently, and blockchain (Blockchain) has obviously been used by many It seems that blockchain technology can be used in all walks of life, but to a certain extent, it is like a black box. Everyone knows that blockchain has many features and benefits, but they don’t know how it does it. In fact, as long as you understand the principles of blockchain, you don’t have to be so hesitant.

Blockchain is not a single innovative technology, but brings together many cross-field technologies, including cryptography, mathematics, algorithms and economic models, combined with peer-to-peer network relationships, using mathematical foundations to It can establish a trust effect and become a decentralized system that can operate without relying on mutual trust or a single centralized organization. Bitcoin is the first P2P system created using blockchain technology. Electronic cash system is used to implement a digital currency system that is decentralized and ensures transaction security and traceability.

However, how exactly does the blockchain work, and what key technologies does it contain, making it called a trust machine? In the P2P network, can transaction verification be completed without going through traditional trust institutions (such as banks, stock exchanges, third-party institutions and other centralized institutions)?

To understand the operating principle of the blockchain, you can first distinguish between the two parts of the transaction (Transaction) and the block (Block). Here we start from the generation of a transaction in the blockchain to the completion of verification. The process and diagram of a block to understand the operating principle of the blockchain, and further dismantle the five key blockchain technologies to see how it can achieve what everyone calls a zero-trust foundation, decentralization, and traceability It cannot be tampered with.

Looking at the blockchain operation process from a transaction

In the Bitcoin blockchain, when a transaction is generated through a certain node or wallet, the transaction Needs to be sent to other nodes for verification. The method is to encrypt the transaction data with a digital signature and use the Hash function to obtain a unique hash value representing the transaction, and then broadcast this hash value to other participating nodes in the Bitcoin blockchain network for verification. .

Generate a new transaction

When a new transaction is generated, it will first be broadcast to other participating nodes in the blockchain network

Each node will put several new transactions into the block

Each node will collect several unverified transaction hash values ​​into the block, and each block can contain hundreds or thousands of transactions. Transactions

Determine who will verify these transactions

Each node performs proof-of-work calculations to determine who can verify the transaction, and the node that calculates the result the fastest will verify the transaction. This is the way to achieve consensus.

The node that obtains the verification right will broadcast the block to all nodes

The node that completes POW the fastest will broadcast its block to other nodes
< br />Each node verifies and connects the new block

Other nodes will confirm whether the transaction contained in this block is valid, confirm that it has not been repeatedly spent and has a valid digital signature, and then accept the block , at this time the block is officially connected to the blockchain, and the data can no longer be tampered with.

Transaction verification completed

Once all nodes accept the block, the previous blocks that have not completed the POW work will become invalid, and each node will re-create a block and continue POW calculation work next time.

It can be seen that the principle of blockchain is not complicated, and its wide application is natural. There are many companies that have achieved fruitful results in applying blockchain principles to reality. Bubi Company is a leading blockchain service provider in China. It has made many breakthroughs in blockchain technology platforms and can meet the needs of tens of millions of people. level user-scale scenarios, and has the ability to quickly build upper-layer application services. Bubi blockchain platform is divided into basic framework layer (BubiChain) and application adaptation layer (Bubi Application Adapters).

Ⅶ What is blockchain and where can you learn it

Definition of blockchain

In a narrow sense, blockchain is a way to store data in chronological order Blocks are connected in a sequential manner to form a chain data structure, and are cryptographically guaranteed to be a distributed ledger that cannot be tampered with or forged.

Broadly speaking, blockchain technology uses block chain data structures to verify and store data, uses distributed node consensus algorithms to generate and update data, and uses cryptography to ensure Security of data transmission and access, a new distributed infrastructure and computing method that uses smart contracts composed of automated script codes to program and operate data.

There are many channels to learn about blockchain

① You can buy some blockchain-related books and learn some blockchain-related knowledge in your spare time. I can also take notes and look up relevant information

②Watch some blockchain videos on the Internet. The content is easy to understand and comes with relevant examples, which is also very good. a way of learning.

③You can participate in some offline blockchain learning and exchange meetings, or participate in some training courses, and teachers will specifically answer your questions.

To sum up

All roads lead to Rome, and there are many channels to learn blockchain. The one that suits you is the one that suits you.The best

Ⅷ Illustration of what is blockchain

Blockchain is so popular that it has begun to affect my life. I don’t even want to understand it anymore. Let’s look at it today. See what exactly blockchain is.

Structure of this article:

As its name suggests,
A blockchain is a chain composed of a set of blocks.
A block is a block of information that contains information. , the chain also contains information.

Blockchain technology was first developed by a group of researchers in 1991 to time-stamp digital documents so that these documents cannot be tampered with. It essentially played no other role after that, until 2009, when Satoshi Nakamoto used blockchain technology to create the digital cryptocurrency Bitcoin.

A blockchain is a distributed ledger that is completely open to everyone. It has a very interesting property: once certain data is recorded in a blockchain, the data is very It is difficult to change.

Let’s take a look at the composition of a block:

Each block contains some data, the hash value of this block, and the hash value of the previous block. Hope value.

The data saved in the block is related to the type of blockchain. For example, the blocks in the Bitcoin blockchain save relevant transaction information, including sellers, buyers, and transaction Bitcoins. quantity.

Each block contains a hash value. The hash value is used to identify a block and all the content it contains, and it is unique, like a fingerprint. Once a block is created, its hash value is calculated accordingly. If you change something in the block, the hash value will change. If the fingerprint of a block changes, it will no longer be the previous block.

The third element contained in the block is the hash value of the previous block. This element allows links to be formed between blocks and makes the blockchain very secure.

Suppose we have a blockchain containing 3 blocks
Each block contains its own hash value and the hash value of the previous block
No. 3 Block points to block No. 2, and block No. 2 points to block No. 1
Block No. 1 is a bit special, it cannot point to the previous block because it is the first
We put 1 The block number is called the genesis block.

Now suppose we tamper with the second block
This will cause the hash value of the second block to change
This will then cause block 3 and all subsequent blocks connected to block 3 to become illegal
Because the previous block number they stored has now become illegal
, changing one block alone will jointly cause all subsequent content to become invalid.

But to prevent tampering, hashing is not enough
Because today’s computer computing speed is powerful enough and can calculate thousands of hash values ​​per second
This way You can tamper with a block and recalculate the hashes of other blocks, making your block legal again.

So in order to reduce this risk, the blockchain also uses a technology called proof of work
This is a mechanism that slows down the creation process of new blocks
In the Bitcoin area In the blockchain, it takes about 10 minutes to complete the required proof of work and add a new block to the blockchain
This mechanism makes the tampering of the blockchain more difficult
because once it is tampered Once a block is obtained, the proof of work of all subsequent blocks needs to be recalculated.

Therefore, the security of blockchain technology mainly comes from hash value and workload proof mechanism.

Blockchain also has a mechanism to protect its own security, which is distributed
Compared to using a centralized entity to manage the blockchain network, blockchain uses A peer-to-peer network that anyone can join
When someone joins this network, he will get a copy of the entire blockchain
This person can use this to verify that all The blocks are still legal and untampered, that is, different nodes can use this to verify each other.

When someone creates a new block,
the new block is sent to everyone on the network.
Everyone then verifies the block to ensure that it has not been tampered with.
If everything is verified correct, then everyone can add the new block to their own area. On the blockchain
We can call it that everyone on the network has reached a "consensus".

All nodes in the blockchain network reach a consensus
They agree on which blocks in the network are legal and which are illegal
Those that have been tampered withThe block will be rejected by other users on the network
So, to successfully tamper with a blockchain, you need to tamper with all blocks on the blockchain
Recomplete the proof of work for each block , and control more than 50% of the users in the blockchain network
Only in this way will the blocks you tamper with will be recognized by everyone
It can be said that this is basically impossible to do!

Blockchain technology itself is also constantly developing
For example, a later technological improvement is called smart contracts
Smart contracts are simple programs stored on the blockchain
br /> It can automatically execute based on the conditions recorded in the contract. As long as the conditions are met, transactions will be automatically completed in accordance with the contract
For example, automated Bitcoin transactions can be realized under specific conditions.

Learning materials:
https://www.youtube.com/watch?v=SSo_EIwHSd4

Ⅸ What is "Blockchain Cat Raising" and how to play it (very Detailed tutorial)

This time, cats meow in the blockchain world again.

In a few days, "blockchain cat raising" has become a hot topic in the currency circle.

CryptoKitties is the first virtual pet game that uses blockchain technology and runs on the Ethereum network.

Her appearance has a certain historical significance, and it has now become the most popular project on the Ethereum blockchain, once accounting for 20% of the entire Ethereum traffic. The market has reached millions of dollars in transaction volume and is still growing rapidly...

The concept is simple. You use Ethereum to buy a cat. Each cat is unique. As long as you don't sell it, it is 100% owned by you and cannot be copied or destroyed.

The fun part is that you can go to the market to find cats to breed with, or you can buy a cat, match two of them, and the resulting kitten will be yours.

Each kitten extracts a certain sequence from its parents and combines it. Whether it is coat color, markings, pupils, hairstyle, expression, tail and other characteristics, they are all random. There are 4 billion types in total. Possibility of change. Then you can sell your cat on the market, and you set the price yourself.

Another point is that every 15 minutes, a gen 0 creation cat will be born. Its price is equivalent to the average price of the latest 5 cats sold, plus an increase of 50%. .Of course, Genesis cats are very popular. After all, they are virgins and they give birth to kittens the fastest.

Isn’t this a bit like our story of chickens laying eggs and eggs laying chickens, and our descendants are endless?

Of course, having a baby takes time.

The birth of a kitten has always been from fast to slow~slow~slow~, and the gap ranges from one minute to a week.

The shorter the time it takes for your cat to give birth, the better. This allows the newborn CryptoKitties to be sold quickly and continue to breed. This also means an increase in income.

The more babies you have, the longer the cat’s cooldowns will take, and the birth rate will also slow down.

Another interesting thing is that giving birth to kittens is a complex and random breeding system, which means that there are always some mutant attributes (attributes) appearing in it, and these become collectibles or in-demand items. .

1. Enter the official website of CryptoKitties: cryptokitties.co and click sign in to jump to the registration page. You need to install the Ethereum light wallet MetaMask plug-in on your chrome or firefox browser. (This process needs to be learned. There are three ways here. Do it as you like, guest. Password: 1rjo)

2. Click on the Mertamask plug-in to install it.

3. Accept the terms and enter your password.

4. You must remember the generated 12 English word passwords. Save it together with the jason file.

5. Then the wallet creation is completed. Enter the cryptokitties.co website to see your account, set your name, email, etc.

Method 1: If you have ETH in other Ethereum wallets, such as imtoken, you can directly transfer it to your CryptoKitties address.

Method 2: Two of the three OTC Bitcoin exchanges mentioned in this article: Coincola and bitcoinworld both support ETH transactions, and you can also transfer them directly.

Method three: It is the coinbase recommended by Matamask, but it shows US only.

1. Go to the marketplace to find the cat you like (as shown below).

2. After you like it, click buy now.

The details page shows the cat’s detailed information, serial number, and price trend chart (the price continues to increase or decrease over time in 1 or 2 days) ), the current purchase price, and the cooling time for giving birth to kittens, etc.

3. After clicking ok, buy this kitty, matamask will pop up to display the detailed estimated cost. If there are no results, maybe your mining fee is not enough, or the cat is sold. Try more. The max transaction fee shows the maximum transaction fee, which is generally not reached. Just wait for the transaction to be completed after the summit. To cancel the transaction, click reject.

During the transaction process, you can click on the transaction to enter https://etherscan.io to view the details. Or view historical transaction information on the ECG-like icon on the right side of the website.

4. Transaction successful! Congratulations, you have your first virtual cat. How to make more?

One way, life.

Pair up two by two. There is also a transaction fee for giving birth to kittens. The speed of birth depends on the speed of the parents.

Breed kitty gives birth to kittens;

Sell kitty sells kittens

Gift kitty gives kittens to friends

Another way is to rent.

Sire to the public, which means renting out your cat as a male cat, setting the initial price and end price and date, and acting as a sperm bank.

sire to my kitties means letting your two cats XXOO have kittens.

The final way is to sell.

When a kitten is born, you will be notified by email. You can choose to sell, set the price and then sell.

If someone buys it, you will be notified by email.

Okay, let’s be cat slaves happily~

Original text: http://li-wu.net/how-to-cryptokitties.html