区块链中一个区块的随机数是什么意思,区块链中一个区块的随机数是什么

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A. Are there 7 core technologies for blockchain operation that you should know?

How many of the 7 core technologies for blockchain operation do you know?< br>1. Blockchain links
As the name suggests, blockchain is a chain composed of blocks. Each block is divided into two parts: block header and block body (including transaction data). The block header includes the hash (PrevHash) value (also called hash value) of the previous block used to implement block linking and the random number (nonce) used to calculate the mining difficulty. The hash value of the previous block is actually the hash value of the header of the previous block, and the rules for calculating random numbers determine which miner can obtain the power to record the block.
2. Consensus Mechanism
Blockchain was born with Bitcoin and is the basic technical architecture of Bitcoin. Blockchain can be understood as a decentralized accounting system based on the Internet. A decentralized digital currency system like Bitcoin requires blockchain to ensure the consistency of accounting by each honest node without a central node. Therefore, the core of blockchain technology is a consensus mechanism that reaches a consensus on the legality of transactions among individuals who have no basis for trust in each other without central control.
There are currently four main categories of blockchain consensus mechanisms: PoW, PoS, DPoS, and distributed consensus algorithms.
3. Unlocking scripts
Scripts are an important technology for automatic verification and automatic execution of contracts on the blockchain. Each output of each transaction does not strictly point to an address, but to a script. A script is like a set of rules that govern how the recipient can spend the assets locked on this output.
The legality verification of transactions also relies on scripts. Currently it relies on two types of scripts: locking scripts and unlocking scripts. The locking script is a condition added to the output transaction, implemented through a script language, and is located at the output of the transaction. The unlocking script corresponds to the locking script. Only if the conditions required by the locking script are met, the corresponding assets on this script can be spent, which is located at the input of the transaction. Many flexible items can be expressed through scripting language. The interpretation script is similar to a "virtual machine" in our programming field, which is distributed and runs on every node in the blockchain network.
4. Transaction Rules
Blockchain transactions are the basic units that constitute blocks, and are also the actual effective content that the blockchain is responsible for recording. A blockchain transaction can be a transfer or other transactions such as the deployment of smart contracts.
In the case of Bitcoin, a transaction refers to a payment transfer. The trading rules are as follows:
1) The input and output of the transaction cannot be empty.
2) For each input of the transaction, if its corresponding UTXO output can be found in the current transaction pool, the transaction will be rejected. Because the current transaction pool is a transaction that has not been recorded in the blockchain, and each input of the transaction should come from a confirmed UTXO. If found in the current transaction pool, it is a double spend transaction.
3) In transactionFor each input, its corresponding output must be a UTXO.
4) Each input unlocking script must work with the corresponding output locking script to verify the compliance of the transaction.
5. Transaction Priority
The priority of blockchain transactions is determined by the blockchain protocol rules. For Bitcoin, the priority of a transaction being included in a block is determined by the time it takes for the transaction to be broadcast to the network and the size of the transaction. As the time it takes for a transaction to be broadcast to the network increases and the chain age of the transaction increases, the priority of the transaction is increased and will eventually be included in the block. For Ethereum, the priority of a transaction is also related to the transaction fee that the publisher of the transaction is willing to pay. The higher the transaction fee that the publisher is willing to pay, the higher the priority of the transaction being included in the block.
6.Merkle proof
The original application of Merkle proof is the Bitcoin system (Bitcoin), which was described and created by Satoshi Nakamoto in 2009. The Bitcoin blockchain uses Merkle proofs in order to store transactions in every block. This makes the transaction unable to be tampered with and makes it easy to verify whether the transaction is included in a specific block.
7.RLP
RLP (Recursive Length Prefix, recursive length prefix encoding) is a main encoding method for object serialization in Ethereum. Its purpose is to encode any nested sequence of binary virtual data. Lu Ji

B. Why are the letters in the blockchain private key only between a-f

Private key: It is actually a set of random numbers. About the blockchain We have already introduced the random number
Public key: The private key is generated by the elliptic curve encryption algorithm, but the private key cannot be obtained through the public key. The function of the public key is to use your own private key to encrypt information when transacting with the other party, and then the other party uses its own public key to decrypt and obtain the original information. This process is commonly known as signature.
Address: Since the public key is too long and is inconvenient to use in transactions, the public key hash is encrypted with SHA256, RIPEMD160, and Base58 algorithms to generate an address

First, use a random number generator to generate a "Private key". Subsequent public keys and addresses will be generated by the private key, so the importance of the private key can be summarized in one sentence: "Whoever masters the private key has the right to use the wallet!"

『Private key 』The 'public key' is generated through elliptic curve algorithm (SECP256K1) algorithm encryption. This is an asymmetric one-way encryption algorithm. Knowing the private key can calculate the public key, but knowing the public key cannot reversely calculate the private key

The "public key" undergoes a one-way Hash algorithm (SHA256, RIPEMD160 )Generate "Public Key Hash"

Convert aThe byte address version number is connected to the "Public Key Hash" header (for the pubkey address of the Bitcoin network, this byte is "0"), and then SHA256 operations are performed twice on it, and the first 4 characters of the result are The section serves as the check value of the "public key hash" and is connected at the end.

Use BASE58 to encode the result of the previous step (customized version of Bitcoin) to get the "wallet address".

C. 108 knowledge points for getting started with blockchain

1. What is blockchain

Putting the information of multiple transactions and indicating the block The information is packaged together, and the verified package is the block.

Each block stores the hash value of the previous block, creating a relationship between blocks, that is to say, a chain. Together they are called blockchain.

2. What is Bitcoin

The concept of Bitcoin was proposed by Satoshi Nakamoto in 2009, with a total number of 21 million. The Bitcoin chain generates a block approximately every 10 minutes, and this block is mined by miners for 10 minutes. As a reward to miners, a certain number of Bitcoins will be issued to miners, but this certain number is halved every four years. Now it's 12.5. If this continues, all Bitcoins will be available in 2040.

3. What is Ethereum

The biggest difference between Ethereum and Bitcoin is the smart contract. This allows developers to develop and run various applications on it.

4. Distributed ledger

It is a database that is shared, replicated and synchronized among network members. To put it bluntly, all users on the blockchain have accounting functions and the content is consistent, which ensures that the data cannot be tampered with.

5. What is quasi-anonymity?

I believe everyone has a wallet, and the wallet address (a string of characters) used to send transactions is quasi-anonymity.

6. What is open transparency/traceability

The blockchain stores all data from history to the present, anyone can view it, and can also view any data in history.

7. What is tamper-proof

Historical data and current transaction data cannot be tampered with. The data is stored in the block on the chain and has a hash value. If the block information is modified, its hash value will also change, and the hash values ​​of all blocks following it must also be modified to form a new chain. At the same time, the main chain is still conducting transactions to generate blocks. The modified chain must always generate blocks synchronously with the main chain to ensure that the length of the chain is the same. The cost is too high, just to modify a piece of data.

8. What is anti-DDoS attack

Ddos: Hackers control many people’s computers or mobile phones and allow them to access a website at the same time. Since the bandwidth of the server is limited, the influx of large amounts of traffic may cause the website to fail to work properly and suffer loss. However, the blockchain is distributed and there is no central server. If one node fails, other nodes will not be affected. Theoretically, if more than 51% of the nodes are attacked, problems will occur.

9. Definition of main chain

Taking Bitcoin as an example, at a certain point in time, a block is mined by two miners at the same time, and then 6 blocks are generated first. The chain of blocks is the main chain

10. Single chain/multi-chain

Single chain refers to the data structure that handles everything on one chain. The core essence of the multi-chain structure is composed of public chain + N sub-chains. There is only one, but in theory there can be countless sub-chains, and each sub-chain can run one or more DAPP systems

11. Public chain/alliance chain/private chain

Public Chain: Everyone can participate in the blockchain

Alliance chain: Only alliance members are allowed to participate in accounting and query

Private chain: Writing and viewing permissions are only controlled by one person In the hands of the organization.

12. Consensus layer, data layer, etc.

There are six overall structures of the blockchain: data layer, network layer, consensus layer, incentive layer, contract layer, and application layer. Data layer: a layer that records data, belonging to the underlying technology; network layer: a structure for building a blockchain network, which determines how users are organized. Consensus layer: Provides a set of rules to allow everyone to reach agreement on the information received and stored. Incentive layer: Design incentive policies to encourage users to participate in the blockchain ecosystem; Contract layer: Generally referred to as "smart contracts", it is a set of contract systems that can be automatically executed and written according to their own needs. Application layer: Applications on the blockchain, similar to mobile apps. Former Distributed Storage R&D Center

13. Timestamp

The timestamp refers to January 1, 1970 Day 0 hours 0 minutes 0 seconds 0... The total number of seconds from the current time to now, or the total number of nanoseconds and other very large numbers. Each block is generated with a timestamp indicating when the block was generated.

14. Block/block header/block body

Block is the basic unit of blockchain, and block header and block body are components of blockchain. The information contained in the block header includes the hash of the previous block, the hash of this block, timestamp, etc. The block body is the detailed data in the block.

15. Merkle tree

Merkle tree, also called binary tree, is a storageA data structure for storing data. The bottom layer is the original data contained in all blocks. The upper layer is the hash value of each block. The hash of this layer is combined in pairs to generate a new hash value, forming a new layer. , and then go up layer by layer, until a hash value is generated. Such a structure can be used to quickly compare large amounts of data, and you can quickly find the bottom-level historical data you want without downloading all the data.

16. What is expansion?

The size of a Bitcoin block is about 1M and can save 4,000 transaction records. Expansion means making the block larger so that more data can be stored.

17. What is a chain?

Each block will save the hash of the previous block, creating a relationship between the blocks. This relationship is a chain. Data such as block transaction records and status changes are stored through this chain.

18. Block height

This is not the height mentioned in terms of distance. It refers to the total number of blocks between the block and the first block on the chain. This height indicates which block it is, and is just for identification purposes.

19. Fork

Two blocks were generated at the same time (the transaction information in the block is the same, but the hash value of the block is different), and then in Two chains are forked from these two blocks. Whoever generates 6 blocks from these two links first will be the main chain, and the other chain will be discarded.

20. Ghost Protocol

Mining pools with high computing power can easily generate blocks faster than mining machines with low computing power, resulting in most of the blocks on the blockchain being generated by these mining pools with high computing power. However, the blocks generated by mining machines with low computing power are not stored on the chain because they are slow, and these blocks will be invalid.

The ghost protocol allows blocks that should be invalidated to remain on the chain for a short time, and can also be used as part of the proof of work

. In this way, miners with small computing power will contribute more to the main chain, and large mining pools will not be able to monopolize the confirmation of new blocks.

21. Orphan block

As mentioned before, orphan blocks are blocks generated at the same time. One of them forms a chain, and the other does not form a chain. Then this block that does not form a chain is called an orphan block.

22. Uncle block

The orphan block mentioned above, through the ghost protocol, makes it part of the proof of work, then it will not be discarded and will be saved in the main chain superior. This block is the next one

23 replay attack

It is the hacker’s attack that has already been sentThe message sent to the server is sent again. Sometimes this can deceive the server into responding multiple times.

24. Directed acyclic graph

Also called data set DAG (directed acyclic graph), DAG is an ideal multi-chain data structure. Most of the blockchains mentioned now are single chains, that is, one block is connected to another block, and DAG is multiple blocks connected. The advantage is that several blocks can be generated at the same time, so the network can process a large number of transactions at the same time, and the throughput will definitely increase. However, there are many shortcomings and it is currently in the research stage.

25. What is mining

The mining process is to perform a series of conversions, connections and hash operations on the above six fields, and continue to try them one by one. The random number you are looking for, and finally successfully find a random number that meets the conditions: the value after hashing is smaller than the hash value of the preset difficulty value, then the mining is successful, and the node can broadcast the area to neighboring nodes. block, neighboring nodes receive the block and perform the same operation on the above six fields to verify compliance, and then forward it to other nodes. Other nodes also use the same algorithm to verify. If there are 51% of nodes in the entire network If all verifications are successful, even if this block is truly "mined" successfully, each node will add this block to the end of the previous block, delete the list in the block that is the same as its own record, and resurrect again. the above process. Another thing to mention is that regardless of whether the mining is successful or not, each node will pre-record the reward of 50 Bitcoins and the handling fees of all transactions (total input-total output) in the first item of the transaction list (this is " The most fundamental purpose of "mining" is also the fundamental reason to ensure the long-term stable operation of the blockchain), the output address is the address of this node, but if the mining is unsuccessful, the transaction will be invalidated without any reward. Moreover, this transaction called "production transaction" does not participate in the "mining" calculation.

26. Mining machines/mines

Mining machines are computers with various configurations, and computing power is the biggest difference between them. A place where mining machines are concentrated in one place is a mining farm

27. Mining pool

Miners unite to form a team, and the computer group under this team is a mining pool. Mining rewards are distributed based on your own computing power contribution.

28. Mining difficulty and computing power

Mining difficulty is to ensure that the interval between generating blocks is stable within a certain short time, such as Bitcoin is issued in 10 minutes

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Block 1. The computing power is the configuration of the mining machine.

29. Verification

When verification in the blockchain is a confirmation of the legality of the transaction, each node will verify the transaction once when the transaction message is propagated between nodes. Whether the transaction is legal. For example, verify whether the transaction syntax is correct and whether the transaction amount is greater than0, whether the entered transaction amount is reasonable, etc. After passing the verification, it will be packaged and handed over to the miners for mining.

30. Transaction broadcast

The node sends information to other nodes through the network.

31. Mining fees

For the blockchain to work non-stop like a perpetual motion machine, miners need to maintain the system. Therefore, the miners must be given favorable fees to make it sustainable.

32. Transaction confirmation

When a transaction occurs, the block recording the transaction will be confirmed for the first time, and will be confirmed in every area on the chain after the block. Block is reconfirmed: When the number of confirmations reaches 6 or more, the transaction is generally considered safe and difficult to tamper with.

33. Double transaction

That is, I have 10 yuan, I use the 10 yuan to buy a pack of cigarettes, and then instantly use the 10 yuan that has not yet been paid. Bought another cup of coffee. So when verifying the transaction, you need to confirm whether the 10 yuan has been spent.

34. UTXO unspent transaction output

It is a data structure containing transaction data and execution code, which can be understood as digital currency that exists but has not yet been consumed.

35. Transactions per second TPS

That is throughput, tps refers to the number of transactions the system can process per second.

36. Wallet

Similar to Alipay, it is used to store digital currencies, and blockchain technology is more secure.

37. Cold wallet/hot wallet

A cold wallet is an offline wallet. The principle is to store it locally and use QR code communication to prevent the private key from touching the Internet. A hot wallet is an online wallet. The principle is to encrypt the private key and store it on the server. When it is needed, it is downloaded from the server and decrypted on the browser side.

38. Software Wallet/Hardware Wallet

A software wallet is a computer program. Generally speaking, a software wallet is a program that interacts with the blockchain and allows users to receive, store, and send digital currencies and can store multiple keys. Hardware wallets are smart devices that specialize in handling digital currencies.

39. Airdrop

The project sends digital currency to each user’s wallet address.

40. Mapping

Mapping is related to the issuance of blockchain currency and is a mapping between chains. For example, there are some blockchain companies that have not completed the development of the chain in the early stage. They rely on Ethereum to issue their own currency. The issuance and transactions of the early currency are all operated on Ethereum. As the company develops, the company's own chainAfter the development is completed, the company wants to map all the previous information on Ethereum to its own chain. This process is mapping.

41. Position

Refers to the ratio of the investor’s actual investment to the actual investment funds

42. Full position

All funds are bought Enter Bitcoin

43. Reduce the position

Sell some of the Bitcoins, but not all of them

44. Heavy positions

Compared with Bitcoin, Bitcoin accounts for a larger share of funds

45. Short position

Compared with Bitcoin, the share of funds is larger

46. Short position

Sell all the Bitcoins you hold and convert them all into funds.

47. Stop loss

After obtaining a certain profit, sell the Bitcoin held to keep the profit

48. Stop loss

After losses reach a certain level, sell the Bitcoins you hold to prevent further losses

49. Bull market

Prices continue to rise and the outlook is optimistic

50. Bear market

Prices continue to fall, and the outlook is bleak

51. Long (long)

The buyer believes that the currency price will rise in the future, buys the currency, and waits for the currency price After rising, sell at a high price to take profits

52. Short position (short selling)

The seller believes that the currency price will fall in the future, and sells the currency he holds (or borrows it from the trading platform) (coin) sell, wait for the price of the currency to fall, buy at a low price to take profits

53. Open a position

Buy virtual currencies such as Bitcoin

54 . Cover the position

Buy Bitcoin and other virtual currencies in batches, for example: buy 1 BTC first, and then buy 1 BTC later

55. Full position

All funds are purchased at one time to buy a certain virtual currency

56. Rebound

When the currency price falls, the price rebounds and adjusts because it falls too fast

57 .Consolidation (sideways)

The price fluctuation is small and the currency price is stable

58. Yin fall

The currency price declines slowly

59. Diving (Waterfall)

The currency price fell rapidly and to a great extent

60. Cutting meat

After buying Bitcoin, the price of the currency fell. To avoid expanding losses, sell Bitcoin at a loss. Or after borrowing the currency to go short, the currency price rises, and you buy Bitcoin at a loss

61. Hold on

Expect the currency price to rise, but unexpectedly the currency price falls after buying; or expect the currency price fell, but unexpectedly, after selling, the currency price rose

62. Unwinding

After buying Bitcoin, the currency price fell, causing a temporary book loss, but then the currency price rebounded and the loss was reversed To make a profit

63. Go short

After selling Bitcoin because of the bearish market outlook, the price of the currency continued to rise, and I was unable to buy it in time, so I failed to make a profit

64. Overbought

The currency price continues to rise to a certain height, the buyer's power is basically exhausted, and the currency price is about to fall

65. Oversold

The currency price continues to fall to a certain low, the seller's power has basically been exhausted, and the currency price is about to rise

66. Lure bulls

The currency price has been consolidating for a long time, and it is more likely to fall. Most of the short sellers have sold Bitcoin, and suddenly the short sellers pulled up the price of the currency, inducing the long parties to think that the price of the currency will rise and buy one after another. As a result, the short sellers suppressed the price of the currency and locked up the long parties.

67. Lure shorts

After buying Bitcoin, bulls deliberately suppress the price of the currency, making short sellers think that the price of the currency will fall and sell them one after another. As a result, they fall into the trap of bulls

68. What is NFT

The full name of NFT is "Non-Fungible Tokens", which is a non-fungible token. Simply put, it is an indivisible token on the blockchain. Copyright certificate is mainly used to confirm and transfer the rights of digital assets. The difference from digital currency is that it is unique and indivisible. In essence, it is a unique digital asset.

69. What is the Metaverse

The Metaverse is a collection of virtual time and space, consisting of a series of augmented reality (AR), virtual reality (VR) and the Internet (Internet) Composed of digital currency, which carries the function of value transfer in this world.

70. What is DeFi

DeFi, the full name is Decentralized Finance, which is "decentralized finance" or "distributed finance". "Decentralized finance", as opposed to traditional centralized finance, refers to various financial applications established in open decentralized networks. The goal is to establish a multi-level financial system based on blockchain technology and cryptocurrency. as a basis, re-create andImprove the existing financial system

71. Who is Satoshi Nakamoto?

72. Bitcoin is different from Q Coin

Bitcoin is a decentralized digital asset with no issuing entity. Q Coin is an electronic currency issued by Tencent. It is similar to electronic points, but it is not actually a currency. Q Coin requires a centralized issuing institution. Q Coin can only be recognized and used because of the credit endorsement of Tencent. The scope of use is also limited to Tencent's games and services. The value of Q coins is entirely based on people's trust in Tencent.

Bitcoin is not issued through a centralized institution, but it is widely recognized around the world because Bitcoin can self-certify its trust. The issuance and circulation of Bitcoin are jointly accounted for by miners across the entire network, and are not A central authority is also needed to ensure that no one can tamper with the ledger.

73. What is a mining machine?

Taking Bitcoin as an example, a Bitcoin mining machine is a professional equipment that competes for accounting rights by running a large amount of calculations to obtain new Bitcoin rewards. It is generally composed of a mining chip, a heat sink and a fan, and only performs A single calculation program consumes a lot of power. Mining is actually a competition between miners for computing power. Miners with more computing power have a greater probability of mining Bitcoin. As the computing power of the entire network increases, it becomes increasingly difficult to mine bits with traditional equipment (CPU, GPU), and people have developed chips specifically for mining. The chip is the core part of the mining machine. The operation of the chip will generate a large amount of heat. In order to dissipate heat, Bitcoin mining machines are generally equipped with heat sinks and fans. Users download Bitcoin mining software on their computers, use the software to assign tasks to each mining machine, and then start mining. Each currency has a different algorithm and requires different mining machines.

74. What is quantitative trading?

Quantitative trading, sometimes also called automated trading, refers to the use of advanced mathematical models to replace human subjective judgments, which greatly reduces the impact of investor sentiment fluctuations and avoids extreme fanaticism or pessimism in the market. make irrational investment decisions. There are many types of quantitative trading, including cross-platform trading, trend trading, hedging, etc. Cross-platform trading means that when the price difference between different target platforms reaches a certain amount, sell on the platform with a higher price and buy on the platform with a lower price.

75. Blockchain asset over-the-counter trading

Over-the-counter trading is also called OTC trading. Users need to find their own counterparties and do not need to match the transaction. The transaction price is determined by negotiation between the two parties. The two parties can fully communicate through face-to-face negotiation or telephone communication.

76. What is a timestamp?

The blockchain ensures that each block is connected sequentially through timestamps. Timestamps enable every piece of data on the blockchain to have a time stamp. Simply put, a timestamp proves when something was posted on the blockchain.What happened cannot be tampered with by anyone.

77. What is a blockchain fork?

Upgrading software in a centralized system is very simple, just click "Upgrade" in the app store. However, in decentralized systems such as blockchain, "upgrading" is not that simple, and a disagreement may even cause a blockchain fork. Simply put, a fork refers to a disagreement when the blockchain is "upgraded", resulting in a fork in the blockchain. Because there is no centralized organization, every code upgrade of digital assets such as Bitcoin needs to be unanimously recognized by the Bitcoin community. If the Bitcoin community cannot reach an agreement, the blockchain is likely to form a fork.

78. Soft fork and hard fork

Hard fork means that when the Bitcoin code changes, the old nodes refuse to accept the blocks created by the new nodes. Blocks that do not comply with the original rules will be ignored, and miners will follow the original rules and create new blocks after the last block they verified. A soft fork means that old nodes are not aware of the changes to the Bitcoin code and continue to accept blocks created by new nodes. Miners may work on blocks they have no understanding of, or validation of. Both soft forks and hard forks are "backwards compatible" to ensure that new nodes can verify the blockchain from scratch. Backward compatibility means that new software accepts data or code generated by old software. For example, Windows 10 can run Windows XP applications. Soft forks can also be "forward compatible".

79. Classification and application of blockchain projects

Judging from the current mainstream blockchain projects, blockchain projects mainly fall into four categories: Category 1: Currency; The second category: platform category; the third category: application category; the fourth category: asset tokenization.

80. USDT against the US dollar

USDT is Tether USD, a token launched by Tether that is against the US dollar (USD). 1USDT=1 US dollar, users can use USDT and USD for 1:1 exchange at any time. Tether implements a 1:1 reserve guarantee system, that is, each USDT token will have a reserve guarantee of 1 US dollar, which supports the stability of the USDT price. The unit price of a certain digital asset is USDT, which is equivalent to its unit price in US dollars (USD).

81. Altcoins and alternative coins

Altcoins refer to blockchain assets that use the Bitcoin code as a template and make some modifications to its underlying technology blockchain, among which Those with technological innovations or improvements are also called alternative coins. Because the Bitcoin code is open source, the cost of plagiarism in Bitcoin is very low. You can even generate a brand new blockchain by simply copying the Bitcoin code and modifying some parameters.

82. Three major exchanges

Binance: https://accounts.binancezh.ac/zh-CN

Okex: https://www.ouyi.top/

Huobi: https: //www.huobi.af/zh-cn

83. Market software

Mytoken: http://www.mytoken.com/

Not small Number: https://www.feixiaohao.co/

84. Information website

Babbitt: https://www.8btc.cn

Golden Finance: http://www.jinse.com/

Coin World News: http://www.bishijie.com

85. Blockchain Browser

BTC: https://btc.com/

ETH: https://etherscan.io/

BCH: https://blockchair.com/bitcoin-cash /blocks

LTC: http://www.qukuai.com/search/ltc

ETC: https://gastracker.io/

86. Wallet

Imtoken: https://imatoken.net/

Bitpie: https://bitpie.com/

87. Decentralized Exchange

uniswap: https://uniswap.org

88. NFT Exchange

Opensea: https: //opensea.io

Super Rare: https://superrare.com/

89. Ladder

Bring your own, buy a reliable ladder

90. Platform currency

Digital currency issued by the platform, used to deduct handling fees, transactions, etc.

91. Niumarket, bear market

Bull market: rising market

Bear market: falling market

92. Blockchain 1.0

Based on distributed ledger Currency trading system, represented by Bitcoin

93. Blockchain 2.0

The contract blockchain technology represented by Ethereum (smart contract) is 2.0

94. Blockchain 3.0

In the era of intelligent Internet of Things, it goes beyond the financial field to provide decentralized solutions for various industries

95. Smart Contract

Smart Contract is a computer protocol designed to disseminate, verify or execute contracts in an information-based manner. Simply put, an electronic contract is set in advance and once confirmed by both parties, the contract is automatically executed.

96. What is a token?

The token economy is an economic system with Token as the only reference standard, which is equivalent to a pass. If you own Token, you have rights and interests, and you have the right to speak.

Big data is the means of production, AI is the new productivity, and blockchain is the new production relationship. Big data refers to a collection of data that cannot be captured, managed and processed within a certain time range using conventional software tools. It is a massive, high-growth and high-volume data set that requires new processing models to have stronger decision-making power, insight discovery and process optimization capabilities. Diverse information assets. Simply understood, big data is massive data accumulated over a long period of time and cannot be obtained in the short term. Blockchain can be used as a way to obtain big data, but it cannot replace big data. Big data is only used as a medium running in the blockchain and has no absolute technical performance, so the two cannot be confused. (A simple understanding of production relations is labor exchange and consumption relations. The core lies in productivity, and the core of productivity lies in production tools)

ICO, Initial Coin Offering, initial public token issuance, is the first step in the blockchain digital currency industry. Crowdfunding. It is the most popular topic and investment trend in 2017, and the country launched a regulatory plan on September 4. Speaking of ICO, people will think of IPO, and the two are fundamentally different.

99. Five characteristics of digital currency

The first characteristic: decentralization

The second characteristic: having open source code

The third feature: independent electronic wallet

The fourth feature: constant issuance

The fifth feature: global circulation

100. What is decentralization?

It has no issuer, does not belong to any institution or country, and is a publicly issued currency designed, developed and stored on the Internet by Internet network experts.

100. What is measurement (scarcity)?

Once the total amount of issuance is set, it is permanently fixed, cannot be changed, cannot be over-issued at will, and is subject to global Internet supervision. Because the difficulty of mining and mining changes over time, the longer the time, the greater the difficulty of mining, and the fewer coins are mined, so it is scarce.

101. What is open source code?

The alphanumeric code is stored on the Internet. Anyone can find out the source code of its design, everyone can participate, can mine it, and it is open to the world.

102. What is anonymous transaction? Private wallet private?

Everyone can register and download the wallet online without real-name authentication. It is completely composed of encrypted digital codes. It can be sent and traded globally in real-time point-to-point without resorting to banks or any institutions. It cannot be traced by anyone without my authorization. ,Inquire.

A contract transaction refers to an agreement between a buyer and seller to receive a certain amount of an asset at a specified price at a certain time in the future. The objects of contract trading are standardized contracts formulated by the exchange. The exchange stipulates standardized information such as commodity type, transaction time, quantity, etc. A contract represents the rights and obligations of the buyer and seller.

105. Digital Currency Industry Chain

Chip manufacturers, mining machine manufacturers, and mining machine agents mine and export to exchanges for retail investors to speculate in coins< /p>

106. Who is Erben?

Erben: Digital Currency Value Investor

Investment style: Steady

Building a community: Erben’s Miscellaneous Talks (High Quality Price Investment Community)

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107. Two investment strategies

Combining long and short term, focusing on price investment, no contracts, no short-term play

Reasonable layout, scientific operation, prudent and conservative, making periodic money

108. Two books?

Welcome currency friends and seek common development

D. What is the popular explanation of blockchain

Question 1: What is blockchain and can it be used in popular terms? Explain the principle of 10-point blockchain in easy-to-understand language: decentralized distributed accounting system
The core of blockchain technology is allThe currently participating nodes jointly maintain transactions and databases, which makes transactions based on cryptographic principles rather than trust, so that any two parties that reach an agreement can directly conduct payment transactions without the participation of a third party.
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Technically speaking, a block is a data structure that records transactions, reflecting the flow of funds for a transaction. The blocks of transactions that have been reached in the system are connected together to form a main chain, and all nodes participating in the calculation record the main chain or part of the main chain. A block contains the following three parts: transaction information, hash hash formed by the previous block, and random number. Transaction information is the task data carried by the block, specifically including the private keys of both parties to the transaction, the number of transactions, the digital signature of electronic currency, etc.; the hash formed by the previous block is used to connect the blocks to realize the past The order of transactions; random numbers are the core of transaction completion. All miner nodes compete to calculate the answer to the random number. The node that gets the answer the fastest generates a new block and broadcasts it to all nodes for update, thus completing a transaction.
1.1 What is Blockchain
Blockchain (BlockChain) refers to a technical solution that collectively maintains a reliable database through decentralization and trustlessness. This technical solution mainly allows any number of nodes participating in the system to associate and generate a series of data blocks (blocks) using cryptographic methods. Each data block contains all the information exchange data of the system within a certain period of time, and generates The data fingerprint is used to verify the validity of its information and chain to the next database block.
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In layman’s terms, blockchain technology refers to a way for all people to participate in accounting. Behind all systems there is a database, which is a big ledger. Then who will keep this ledger becomes very important. At present, it is whoever owns the system who keeps the accounts. Each bank’s account books are kept by each bank, and Alipay’s account books are kept by Alibaba. But now in the blockchain system, everyone in the system has the opportunity to participate in accounting. If there are new transaction data changes within a certain period of time, everyone in the system can do accounting. The system will judge the person who has the fastest and best accounting during this period, write the recorded content to the ledger, and Send the contents of the ledger during this period to all other people in the system for backup. In this way, everyone in the system has a complete ledger. Therefore, this data becomes very safe. A tamperer needs to modify more than half of the system node data at the same time to truly tamper with the data. Such tampering would be extremely costly, making it nearly impossible. For example, Bitcoin has been running for more than 7 years. Countless hackers around the world have tried to attack Bitcoin, but so far there have been no transaction errors. It can be considered that the Bitcoin blockchain has been proven to be a safe and reliable system.
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1.2 Why is there blockchain innovation?
Human beings need to communicate during their activities, and communication is based onInformation-based. In the past, information circulation was not convenient enough to meet the information needs of market participants, so intermediaries and centers were born. This centralized system has problems such as high cost, low efficiency, value dispersion, "information islands" and insecure data storage. However, due to technical and environmental factors, this system continued to operate for many years until the emergence of the Internet. The starting point of the first generation of the Internet is the TCP/IP protocol, which is an open code that implements a unified format for peer-to-peer transmission of information by all nodes on the network, and brings the basic values ​​of freedom and equality required by a global unified market into programmed, protocol-based, and reliably Execution. The Internet eliminates low-value, high-cost intermediate chains and achieves low-cost and high-efficiency global information transmission in a decentralized manner.
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However, the first generation of the Internet did not solve the problem of information credibility. Activities that can be decentralized on the Internet must be activities that do not require credit endorsement, and activities that require credit guarantee must be activities involving centralized third-party intermediaries. Therefore, Internet technology that cannot establish global credit has encountered great obstacles in its progress - people cannot participate in any value exchange activities on the Internet in a decentralized manner. To realize value exchange, people still need third-party intermediaries based on credit (such as banks, clearing agencies, exchanges). The global centralized credit system still has problems such as high operating costs, low efficiency, and vulnerability to attacks and damage. For example, each country's legal currency has different credit values ​​and incompatible clearing systems, which adds a lot of cost to global trade.
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Therefore, what the second generation Internet must break through is: how to establish global credit in a decentralized manner? Let...>>

Question 2: What is blockchain? What does it mean in layman’s terms? What is China’s attitude towards blockchain? What can blockchain do? Blockchain, a great technology that accompanied the birth of Bitcoin, is currently being used in the financial field to significantly reduce transaction costs and improve efficiency, which is enough to excite Wall Street. However, this is just the tip of the iceberg. Its potential applications are very broad and will subvert every aspect of our lives in the future.
Blockchain is an important concept of Bitcoin. It is essentially a decentralized database and serves as the underlying technology of Bitcoin. One of the most basic characteristics of Bitcoin is decentralization. In recent months, financial giants have gradually begun to pay attention to Bitcoin's technology and used it in non-monetary fields, such as stock trading, election voting, etc. (1) Art Industry
Artists can use blockchain technology to declare ownership and issue numberable, 100% edition works in digital form for any type of artwork. It even includes a marketplace where artists can buy and sell through their website without the need for any intermediary services.
(2), roomReal estate industry
Use blockchain technology to solve various problems faced by everyone involved in real estate, including the naming process, land registration, agency intermediaries, etc.
(3) Insurance industry
Financial industry They have always been the most sensitive to advanced technology. Traditional banking and securities industry giants have been involved in the booming blockchain venture capital investment since 2014, with total global investment reaching US$1 billion within two years.
(4) P2P wallet
Personal assets can be traded through this P2P wallet in the future without going through any central institution, such as Bitcoin.
Most blockchains are in their infancy, mainly overseas. There are very few good domestic blockchain projects, so it is not recommended for any non-professionals to invest in blockchain projects. If you are very interested in blockchain technology and have a technical or financial background, it is recommended that you consider starting a business in this area. In terms of the blockchain protocol system, the lowest layer is the underlying technology of the blockchain, including the technical protocols of the blockchain, as well as some platform routing and basic algorithms; in the middle layer, some application interfaces and some credentials must be solved Issuance and verification, including some industry platform services, big data analysis, etc. This is a very rough classification, and there should be more detailed classifications; the top ones are some applications of blockchain, including finance Some applications and some applications in other aspects, the Internet of Things and so on.
Introduction to Bubi Blockchain
Bubi Blockchain has been focusing on the research and development and innovation of blockchain technology and products since its establishment. It has a number of core technologies and has achieved substantial results in many aspects. Radical innovation has resulted in a number of core technological achievements, such as: mathematically provable distributed consensus technology, fast large-scale ledger access technology, multi-chain general ledger technology that supports business expansion, and interconnection technology between heterogeneous blockchains. wait. On April 25, "Gege Points" introduced the concept of blockchain into the points system, jointly opened it up with multiple parties, issued and redeemed points, and promoted the circulation of points. Each cooperative institution can jointly participate in transaction verification, ledger storage, and real-time settlement; the third-party payment platform of the enterprise points issuer makes the entry and exit of points more flexible. Bubi has developed its own basic blockchain service platform, which has been applied in equity, supply chain, points, credit and other fields. Bubi has been committed to building an open value circulation network with decentralized trust as the core, allowing digital assets to flow freely.
A simple understanding of blockchain is a technology at the bottom of Bitcoin, which is also a peer-to-peer electronic cash system that can realize peer-to-peer value delivery. We should distinguish between Bitcoin, Bitcoin blockchain, blockchain and blockchain. Blockchain technology and other concepts. In countries with relatively developed finance in the past, finance and blockchain technology have a long history, and the legislation of digital currencies and blockchain networks is also very important. With the advent of the financial era, large financial institutions are studying blockchain technology, and they have their own teams and concepts.Thinking about technology, banks in various regions are gradually participating in digital currency discussions to apply and support this technology. Not only that, the impact of blockchain on enterprises is also huge. For larger domestic enterprises, Bubi Blockchain is also applied In various fields such as equity, supply chain, points, etc., major domestic financial institutions and enterprises have taken a fancy to the value of new industries and developed their own blockchain platforms. Blockchain has instantly become a new innovative industry in China. In terms of overseas internationalization, the United States has already obtained 15 blockchain patents at the end of last year compared to China. Blockchain financial applications are entering a new stage in an all-round way. Various applications will become more and more in-depth, and related changes will also become more and more profound. It has attracted more and more attention and will form a huge new trend... >>

Question 3: What is blockchain technology? What exactly is blockchain? What is blockchain? 1. Data blockchain is an important concept in the Bitcoin financial system. It records transaction record data on the entire Bitcoin network, and these data are shared by all Bitcoin nodes. Through the data block, we can query each transaction record. A look at the history of Bitcoin transactions. 2. Example: There are three persons A, B, and C. All funds of A and B are kept by C. And every financial transaction must be recorded by C. Now assume that A and B each have 1 million in custody of C. Then: A spends 80,000 yuan to B, then C's account book record will subtract 80,000 yuan from A's name, and add 80,000 yuan to B's name. If B transfers 50,000 yuan to A, C will add 50,000 yuan to A's name and subtract 50,000 yuan to B's name in the account book. A spends 50,000 yuan to B, then C's account book record will subtract 50,000 yuan from A's name, and add 50,000 yuan to B's name. 3. The role of the data blockchain is similar to that of C’s account record book. It records the user’s ownership of Bitcoin and the records of all users’ Bitcoin transactions. It’s just that this “account record book” is recorded by the mining software of every Bitcoin miner on the network. If a Bitcoin transaction is confirmed by the data blockchain, the relevant information will be recorded in the data blockchain. Bitcoin’s “account record book” is called the data blockchain. All data blockchains on the network form Bitcoin’s distributed network database system. 4. The essence of data blockchain technology is a decentralized and distributed structure of data storage, transmission and certification methods. It uses data blocks to replace the current Internet's dependence on central servers, so that all data changes or transaction items are recorded. On a cloud system, the self-certification of data during data transmission is theoretically realized. In a far-reaching sense, this transcends the traditional and conventional information verification paradigm that relies on a center and reduces the cost of establishing global "credit." This point-to-point verification will produce a "basic protocol", which is a new form of distributed artificial intelligence and will establish a new interface and shared interface between human brain intelligence and machine intelligence.

Question 4: What is blockchain: This is a more reasonable explanation of blockchainEasy to understand Blockchain refers to a technical solution that collectively maintains a reliable database through decentralization and trustlessness.
In layman’s terms, blockchain technology refers to a way for all people to participate in accounting. There is a database behind all systems. You can think of the database as a big ledger. Then who will keep this ledger becomes very important. Currently, whoever owns the system keeps the accounts. Tencent keeps the accounts of WeChat, and Alibaba keeps the accounts of Taobao. But now in the blockchain system, everyone in the system has the opportunity to participate in accounting. If there are any data changes within a certain period of time, everyone in the system can do accounting. The system will judge the person who has the fastest and best accounting during this period, write his recorded content into the ledger, and record this Within a period of time, the contents of the ledger are sent to all other people in the system for backup. In this way, everyone in the system has a complete ledger. In this way, we call it blockchain technology.
Blockchain technology has become the darling of the financial community in China and has become a hot topic. Domestic Puyin Group has launched Puyin, a tea-based digital currency.

Question 5: Explain in an easy-to-understand manner what blockchain is. Blockchain can be understood as a database system in a sense. The development of blockchain can be divided into 1.0 and 2.0
1.0 is represented by Bitcoin, and its main application is virtual currency or digital currency application. The blockchain at this time can only be used for simple digital currency transactions.
2.0 is represented by the now popular ethereum (Ethereum) and the upcoming hyperledger. The blockchain at this stage can not only meet the corresponding digital currency transactions, but also use smart contracts to customize currency or asset transactions. If we use the database analogy, the emergence of smart contracts can be understood as allowing users to define functions or stored procedures in the database and call and execute them.
Different from traditional databases, the blockchain introduces consensus mechanism, incentive mechanism, p2p (network), hash and other specific elements, making it open, decentralized and non-tamperable. characteristic.

Question 6: What is blockchain? Can anyone explain it in simple terms? Blockchain is the underlying technology of Bitcoin. It is like a ledger that records all transactions. It is decentralized. What is decentralization? For example, when you buy something on Taobao, you place an order and pay in Alipay. Alipay will not transfer the money to the seller until you receive the goods. Alipay is the third party in that center. Without it, it means decentralization, just like buying things offline. If you pay with one hand and get the goods with the other hand, there is no third party.
The blockchain itself is a series of cryptographic correlations, and the data generatedpiece.
Look carefully to see if it looks like a ledger. The pieces one by one are blocks, and connected together they are the blockchain.
Many companies are developing this technology, including ours, and its prospects are incredible. For details, you can go to our official website and hope to adopt it, thank you

Question 7: What is blockchain technology? What is blockchain? How to explain the concept of blockchain? People in each industry have different understandings, and relevant explanations are gradually emerging due to more and more real-life applications. With the popularization of this blockchain technology, the related results are getting bigger and bigger. If we want to understand this technology, we must have an in-depth understanding of reality.
In the past six months, the concept of blockchain has gradually become popular in China, and a blockchain whirlwind has taken off in the financial circle. Blockchain has attracted the attention and favor of more and more people in the industry due to its unique technical advantages. Blockchain technology, which is decentralized (or multi-centered), highly transparent, cannot be tampered with, and has no single point of failure, is entering the field of vision of financial institutions and enterprises. It has at least been used in digital currency, payment exchange, registration and settlement, Digital assets, traceability and anti-counterfeiting, supply chain, Internet of Things and many other fields have moved from theoretical discussions to practical applications.
"Blockchain" was first introduced with "Bitcoin" released in early 2009. Blockchain has become the basic protocol and technical application for the launch, recording, and circulation of Bitcoin. Although Bitcoin has been controversial since its inception and cannot even be regarded as a "currency" by governments and monetary authorities, the blockchain technology used in Bitcoin has been recognized by governments, including governments and monetary authorities. extensive attention.
Why has blockchain become a rapidly heating up hot technology and topic?
The most important of these may be that the launch of Bitcoin based on blockchain technology has opened up a new relationship with traditional society ( The exploration and attempt of new technologies and rule systems such as Internet user identity verification, wealth confirmation, transaction records, notarization and verification, which have little connection with offline) and are completely applied to the online world (online), provide people with the opportunity to adapt to the Internet society. Development provides alternative paths and unlimited imagination.
Judging from its application in Bitcoin, blockchain is a set of new network blocks (BLOCK, also called communities) formed by combining encryption technology with the Internet. Bitcoin configuration, netizen identity verification, and Bitcoin (value) confirmation formed by mining, Bitcoin transaction records, and extended encryption of Bitcoin cross-block flow (value transfer) (added block and transaction time identification, etc. Internet protocol rules and accounting (Ledger) system including block chain, full encryption, mutual authentication, etc., including factor) registration and verification. Precisely because Bitcoin is not a substitute for offline legal currency, but is issued and managed by non-legal currency authorities, it mainly imitates the model of gold and is completely coordinated by the Internet infrastructure.A new, decentralized online currency (virtual currency) protected and supported by consensus and strict encryption technology, thus forming a new set of currency rules and systems that are different from and not subject to real social laws, and can Buy, sell or exchange fiat currency. It has been more than 8 years since Bitcoin was launched. There has been no record of funds or user information being stolen. Its security has been verified, and its efficiency and cost of fund settlement also have obvious advantages. This has made people's confidence in the blockchain technology used in Bitcoin continue to increase, and people have become more and more aware that although blockchain is a technology and protocol pioneered and applied by Bitcoin, the blockchain Chain is not the same as Bitcoin, and its application is by no means limited to Bitcoin. The application of blockchain can be decentralized or centralized; it can be a public chain model or a private chain model. Therefore, after Bitcoin, blockchain technology is also constantly developing and innovating, and constantly exploring new application fields, especially in the financial field.
The reason why blockchain is valued highly by more and more people is because the development and widespread application of the Internet have caused more and more economic exchanges and transaction activities to be conducted online, and the online world (or online world) society) is rapidly expanding, enriching and active, and online transactions must solve the efficiency and security protection issues of the parties' identity verification, value verification, transaction records, inspection and verification, etc., and require strict intermediaries and agreements (rules or constitutions). In this regard, traditional thinking and customary practices are to follow the development trajectory of the transfer of offline transactions to online and push the common rules and practices of the real (offline) society to the online (network) society. However, in practice, it is increasingly It is difficult to adapt to the needs of online transactions.
For example, for the identity verification of the parties, the natural choice is to use the information on the identity documents protected by the laws of various countries as the basis, and then add account or transaction passwords, as well as facial recognition, iris, fingerprints and other biometrics to conduct online transactions. Verification, but this method first makes the citizen identity information in the cross-border interconnected online world subject to the administrative jurisdiction of real society... >>

Question 8: Easy to understand Explain clearly what is blockchain. The English name of blockchain is Blockchain. Block literally means block, block, and chain means chain, chain. Therefore, together they are translated into blockchain.
1. Use cryptography technology to encrypt and decrypt so that records cannot be tampered with. Common blockchain encryption methods include hash algorithm, RSA algorithm, elliptic curve algorithm, etc.;
2. The huge amount of calculation needs to be supported by a reasonable reward mechanism. Because every transaction must be recorded, Bitcoin’s blockchain has more than 60 gigabytes so far. Every new transaction requires confirmation of the information related to the trading account to ensure that the transaction is valid. The huge amount of calculation requires a computer with powerful computing power.Finish.
In order to encourage the participation of powerful computing power, Bitcoin provides two rewards: one is to issue a certain number of Bitcoins to these computers every day; instead, all transfer fees are awarded to these computers. (The technical term for these computers is "mining machines", and the people who hold the mining machines are called "miners".)
Biying China is working hard on the digitization of assets and has launched the digital currency crowdfunding platform Biying China.

Question 9: What is the so-called "blockchain"? Blockchain itself is a tool called decentralization and trustlessness. For example, when you graduate from university, the current practice is to have a certificate recognized and issued by an authoritative agency as your certificate. This setting is more troublesome, because this is a piece of paper, and paper can be forged, so there will be various gaps. The issuing authority is also a person, and there will be various gaps in the middle. As long as it is related to people, whoever There are various possibilities related to media. The blockchain provides a great opportunity. As soon as you graduate, you will have a record on the blockchain. No one can change this record. This thing exists objectively. You, as a physical existence , and then as a data existence, the blockchain was born. In this case, anyone who wants to check where you graduated can easily solve the problem. This is similar to the big data often involved in social networking (WeChat) and payment platforms (Alipay, Yibao).

Question 10: What does blockchain mean? Regarding blockchain, I think you have already seen the concept on the Internet. Let me explain it based on my understanding!
First, let’s talk about its characteristics: 1. Openness and transparency 2. Decentralization 3. Anonymity 4. Information cannot be tampered with, eliminated 5. No trust cost
Blockchain is like a public ledger , everyone has the right to record and read, and everyone will jointly supervise to ensure its accuracy, and the recorded content will be permanently saved, and can only be added but not deleted! However, as the number of blocks continues to increase, costs will increase and efficiency will decrease. (I’m not sure whether technology can be used to make up for this. I hope someone who understands technology can point it out.)
Blockchain is divided into public chain, private chain, and alliance chain. Public chain: accessible to everyone, everyone has read and write permissions, completely open, transparent and decentralized. Private chain: Open to individuals or institutions, in which the owner of the private chain can set various permissions to make it partially centralized. Alliance chain: Open to specific organizations or groups, it is also "partially decentralized". According to the ledger at the beginning, members can view and transact, but cannot record and confirm bills, or require permission from the alliance. (The latter two do not have cost and efficiency issues)
Regarding blockchain, countries have begun to recruit talents in this area. For this, you can search online for "Central Bank Recruiting Digital Currency R&D Personnel". In addition, you can learn more about blockchain throughTo increase understanding of its existing applications, we usually refer to public chains. Currently used in foreign countries are Bitcoin, Ethereum and other domestic Xiaoyi blockchains
1. Open and transparent :Every piece of data is verified by everyone and can be viewed by everyone at any time.
2. Decentralization: For example, when we shop on Taobao, we conduct transactions through the intermediary Taobao, and blockchain allows both supply and demand parties to directly contact each other for direct transactions through blockchain technology.
3. Anonymity: No personal privacy information is required to complete transactions on the blockchain, only your unique alphanumeric signature is required.
4. Information cannot be tampered with or deleted: Once the data has been verified and recorded, no one has the authority to modify it, let alone delete it!
5. No trust cost: The trust crisis in reality will not appear in the blockchain. Transactions in the blockchain do not require you to trust the other party. Only when both of you have enough "digital assets" to trade can it be carried out, and Under the supervision of the entire network, transactions will not be broken. If you have no idea about the cost of trust, just think about how many intermediaries there are in your city, or just think about Jack Ma, and you will know how big the cost of trust is.
I am still learning more about blockchain. I am Li Ailin. If you have any questions, you can discuss and learn together!

E. How can a novice understand the hash calculation in the blockchain in seconds

​ How can a novice understand the hash calculation in the blockchain in seconds

When I was learning about blockchain, I found that there was a word that appeared repeatedly like a ghost, "Hash", written in English as "HASH".

That classmate who said he had diarrhea, get out of here! !

This "hash" is said to be a function derived from cryptography. Try searching and you will find a bunch of papers, either horizontal or vertical, tables or pictures, and another Hei doesn't understand xyzabc. Brother, I just want to understand the basic knowledge of blockchain. Why is it so difficult for me? ! My longest password is 123456, and the more complicated one is 654321. When it is the most complicated, add an a at the end. The complicated password you wrote to me obviously feels like my brain is being drained, and my only brain cells are dying in batches! In order to let novice students like me understand this, I reluctantly tried to explain hash calculation in a fool's language, not seeking the most accurate but the simplest and easiest to understand. Let’s start below:

# 1. What is a hash algorithm

## 1. Definition: A hash algorithm converts a string of any length into a fixed-length character string.

It can be seen from here that it can be understood as inputting a string of numbers to the "hash operation", and it will output a string of numbers.

If we define the "increment by one algorithm" ourselves, then if we input 1, it will output 2; if we input 100, it will output 101.

If we define the "uppercase algorithm" ourselves, then input "abc" and output "ABC".

Haha, don’t hit me yet! This is really just the concept of a function.

## 2. Features:

What are the characteristics of this hash algorithm compared with my "increment by one algorithm" and "uppercase algorithm"?

1) **Certainty, fast calculation**: The result is the same no matter how you calculate it, and the calculation efficiency is high.

2) **Irreversible**: It means knowing that the output cannot deduce the value of the input.

3) **Unpredictable results**: Just change the input a little, and the results will be completely irregular.

In short, this hash operation is a black box and a good helper for encryption! When you say "11111", it encrypts it into "" for you. When you say "11112", it encrypts it into "" for you. Anyway, the input and output are in the sky and under the ground. Even if the input is related, the two outputs are not related.

# 2. The use of hash operations in the blockchain

## 1. Data encryption

**Transaction data is processed through hashing Hash operation is performed to encrypt, and the corresponding hash value is written into the block header**. As shown in the figure below, a block header contains the hash value of the previous block and the hash value of the next block.

1), **Identify whether the block data has been tampered with**: The hash value of the blockchain can uniquely and accurately identify a block. Any node in the blockchain can pass a simple hash The hash value of this block can be obtained by hash calculation. The calculated hash value has not changed, which means that the information in the blockchain has not been tampered with.

2), **Connect each block into a blockchain**: Each block contains the hash value of the previous block and the value of the next block, which is equivalent to The hash value of the previous block is linked to the end of the previous block, and the hash value of the next block is linked to the head of the next blockchain, thus forming a blockchain with a chain structure.

## 2. Encrypted transaction address and hash

In the block header in the above figure, there is a hash value of the Merkle root (Merkle root), which What is it used for?

First, understand what Merkle root is? It is the root of a binary tree structure. What is a binary tree? What is a root? Just look at the picture below to find out. One can be divided into two, two can be divided into four, and four can be divided into eight. It is called a binary tree. BasicallyThe topmost node is called the root.

Where does this root data come from? After the hash value of each transaction in a block is obtained, the hash values ​​are then hashed, and then hashed, and then hashed again, until the top value is reached.

What’s going on after hashing like this for a long time? What does it do?

1), **Quickly locate each transaction**: Since transactions are stored linearly, locating a transaction requires traversal, which is inefficient and time-consuming. Such a binary tree can quickly Locate the deal you are looking for.

To give an inappropriate example: How to find an arbitrary integer between 0-100? (Assuming the answer is 88) A better way is to ask: 1. Is it larger or smaller than 50? 2. Is it larger or smaller than 75? 3. Is it larger or smaller than 88? You can quickly locate the answer with just a few questions.

2), **Verify whether the transaction data has been tampered with**: From the transaction to the hash value of each binary tree, any change in any number will cause the Merkle root value to change. At the same time, if an error occurs, you can quickly locate the error.

## 3. Mining

There is a parameter in our block header called **random number Nonce. The process of finding this random number is called "mining" **! Any machine on the network only needs to find a suitable number to fill in the Nonce position of its own block, so that the hash value of the data in the 6 fields (80 bytes) of the block header is more than 18 Starting with 0, whoever found "the gold"! Since there is no way for us to write a number that satisfies 18 zeros in advance and then infer Nounce, the only way is to try one by one starting from 0 to see if the result meets the requirements. If not, try the next one until it is found.

What are you looking for this number for? What's the point of doing this?

1), **Fairly find the computer with the strongest computing power**: This is a bit like I have a sand here, and let me tell you that it is the same as a grain of sand on that beach, you Find the same ones. The feasible way is to pick up each pill and compare them! Then the person with the fastest speed is most likely to reach the sand first. This is the so-called "proof of work POW". If you find this sand first, I think you will compare the most and do the most work.

2), **Dynamic adjustment of difficulty**: In order to ensure that a block is produced in 10 minutes, Bitcoin will calculate the difficulty of finding this nonce number every 2016 blocks (2 weeks) , if the average time of these 2016 blocks is less than 10 minutes, increase itDifficulty, if it is more than ten minutes, lower the difficulty. In this way, no matter how the mining computing power of the entire network changes, the random number nonce can be calculated within 10 minutes.

# 3. What are the hash operations?

Having said so many hash operations, it seems that hash operations are just one type, but in fact they are not! As hash operations in cryptography, many schools have been derived from the continuous development. After watching "Man Tou Bao", I still feel that the internal mechanism is too complicated. I will list it as follows for now, so that novices can have an impression and know what is going on.

It can also be seen from the table below that hash operations are also constantly developing. There are various algorithms, and various applications are also flexibly applying single or multiple algorithm. In the Bitcoin system, hash operations basically use the SHA256 algorithm, while Litecoin uses the SCRYPT algorithm. Quark and Dash use many algorithms in series layer by layer. Heavycoin (HAV) However, the following algorithms are connected in parallel, and parts from each are mixed together for use. The POW phase of Ethereum uses the ETHASH algorithm, and ZCASH uses EQUIHASH.

It should be noted that various algorithms for hash operations are constantly being upgraded and improved, and the algorithms used by various currencies are not static and are also being continuously optimized.

**Summary**: Hash operations are widely used in various blockchain projects. Taking Bitcoin as an example, we can see that in **data encryption and transaction data positioning , mining, etc. all play an extremely important role**. As a branch of cryptography, hashing continues to develop and extend. As ordinary novices, if we want to understand some basic concepts of blockchain, understanding this level is enough.

F. What are the three sets of metadata contained in the block header in blockchain technology

1. The hash value of the previous block. Used for pre-index blocks
2. Mining difficulty, random value (for proof of work calculation), timestamp
3. Merkel tree, which can summarize and quickly summarize the verification blocks The root data of all transaction data.

G. How to understand the blockchain economy in a popular way

The principle of blockchain: decentralized distributed accounting system
The core of blockchain technology is All currently participating nodes jointly maintain transactions and databases, which makes transactions based on cryptographic principles rather than trust, so that any two parties that reach an agreement can directly conduct payment transactions without the participation of a third party.
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Technically speaking, a block is a data structure that records transactions, reflecting the flow of funds for a transaction. The blocks of transactions that have been reached in the system are connected together to form a main chain, and all nodes participating in the calculation record the main chain or part of the main chain. A block containsThe next three parts: transaction information, hash hash formed by the previous block, and random number. Transaction information is the task data carried by the block, specifically including the private keys of both parties to the transaction, the number of transactions, the digital signature of electronic currency, etc.; the hash formed by the previous block is used to connect the blocks to realize the past The order of transactions; random numbers are the core of transaction completion. All miner nodes compete to calculate the answer to the random number. The node that gets the answer the fastest generates a new block and broadcasts it to all nodes for update, thus completing a transaction.

1.1 What is Blockchain

Blockchain (BlockChain) refers to a technical solution that collectively maintains a reliable database through decentralization and trustlessness. This technical solution mainly allows any number of nodes participating in the system to associate and generate a series of data blocks (blocks) using cryptographic methods. Each data block contains all the information exchange data of the system within a certain period of time, and generates The data fingerprint is used to verify the validity of its information and chain to the next database block.
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In layman’s terms, blockchain technology refers to a way for all people to participate in accounting. Behind all systems there is a database, which is a big ledger. Then who will keep this ledger becomes very important. At present, it is whoever owns the system who keeps the accounts. The account books of each bank are kept by each bank, and the account books of each bank are kept by Alibaba. But now in the blockchain system, everyone in the system has the opportunity to participate in accounting. If there are new transaction data changes within a certain period of time, everyone in the system can do accounting. The system will judge the person who has the fastest and best accounting during this period, write the recorded content to the ledger, and Send the contents of the ledger during this period to all other people in the system for backup. In this way, everyone in the system has a complete ledger. Therefore, this data becomes very safe. A tamperer needs to modify more than half of the system node data at the same time to truly tamper with the data. Such tampering would be extremely costly, making it nearly impossible. For example, Bitcoin has been running for more than 7 years. Countless hackers around the world have tried to attack Bitcoin, but so far there have been no transaction errors. It can be considered that the Bitcoin blockchain has been proven to be a safe and reliable system.
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1.2 Why is there blockchain innovation

Human beings need to communicate during their activities, and communication is based on information. In the past, information circulated It was not convenient enough to meet the information needs of market participants, so intermediaries and centers were born. This centralized system has problems such as high cost, low efficiency, value dispersion, "information islands" and insecure data storage. However, due to technical and environmental factors, this system continued to operate for many years until the emergence of the Internet. The starting point of the first generation of the Internet is the TCP/IP protocol, which is an open code that implements a unified format for peer-to-peer transmission of information by all nodes on the network, integrating the needs of the global unified market.The necessary basic values ​​of freedom and equality should be programmed, agreed and enforced. The Internet eliminates low-value, high-cost intermediate chains and achieves low-cost and high-efficiency global information transmission in a decentralized manner.
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However, the first generation of the Internet did not solve the problem of information credibility. Activities that can be decentralized on the Internet must be activities that do not require credit endorsement, and activities that require credit guarantee must be centralized activities involving third-party intermediaries. Therefore, Internet technology that cannot establish global credit encounters great obstacles in its progress - people cannot participate in any value exchange activities on the Internet in a decentralized manner. To realize value exchange, people still need third-party intermediaries based on credit (such as banks, clearing houses, exchanges). The global centralized credit system still has problems such as high operating costs, low efficiency, and vulnerability to attacks and damage. For example, each country's legal currency has different credit values ​​and incompatible clearing systems, which adds a lot of cost to global trade.
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Therefore, what the second generation Internet must break through is: how to establish global credit in a decentralized manner? Let value delivery be carried out at low cost and with high efficiency. We need to create a technology in the Internet that can engage in value exchange activities without ensuring that people trust each other, so as to achieve true decentralization and third-party intermediaries, and realize the transformation from the information Internet to The transformation of the Internet of Value.

1.3 Blockchain Application

Bubi Blockchain has been used in equity, supply chain, points and other fields, and is conducting trials and application tests with exchanges and banks. .
Shubei wallet, as a points application on the Bubi blockchain, has recently been launched, which is a good example for the application of blockchain technology in various industries.

1.4 Why the financial industry needs blockchain

Trust is the foundation of the financial industry. In order to maintain trust, the development of the financial industry has spawned a large number of high-cost, inefficient, and single-point-of-failure intermediaries, including custody, third-party payment, notaries, banks, exchanges, etc. Blockchain technology uses new encryption authentication technology and decentralized consensus mechanisms to maintain a complete, distributed, and tamper-proof ledger, allowing participants to communicate through a unified The ledger system ensures the security of funds and information. This has huge implications for finance. Therefore, global financial giants are exploring blockchain applications. On the one hand, they are to prevent the risk of being subverted. On the other hand, they are also "for my own use" to improve efficiency and reduce costs, thereby consolidating, optimizing and expanding existing power.
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First, blockchain can reduce trust risks. Blockchain technology is open source and transparent. Participants in the system can know the operating rules of the system, verify the authenticity and integrity of the ledger content and ledger construction history, and ensure that the transaction history is reliable and has not been tampered with, which is equivalent to Improved system traceabilityResponsibility reduces the trust risk of the system. For example, blockchain can avoid current Internet financial P2P scams, fraud and other incidents.
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Second, blockchain can improve the efficiency of payment, transaction, and settlement. On the blockchain, the process of transaction confirmation is the process of clearing, settlement and auditing. Blockchain uses distributed accounting, and all transactions are displayed in real time on a spreadsheet similar to global sharing, and are settled in real time, greatly improving efficiency. For example, the U.S. securities settlement system is T+3, but blockchain can increase efficiency to the minute level, which can reduce settlement risks by 99%, thereby effectively reducing capital costs and systemic risks.
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Third, blockchain can reduce operating costs. Various financial business systems and back-end work often face long processes and multiple links. Today, both Visa and Master are centralized operations, and currency transfers must go through a third party. This makes cross-border transactions, currency exchange rates, internal accounting, and time costs too high, and brings risks to capital. Blockchain can simplify and automate lengthy financial service processes, reduce front-end and back-end interactions, and save a lot of manpower and material resources. This is of great significance to optimizing financial business processes and improving financial competitiveness. The Bank of Spain believes that blockchain technology will help the financial industry reduce bookkeeping costs by $20 billion by 2022.
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Fourth, blockchain can effectively prevent failures and attacks. The traditional financial model is centered on finance such as exchanges or banks. Once the center fails or is attacked, it may cause the entire network to be paralyzed and transactions to be suspended. The blockchain is supported by many distributed nodes and computer servers on a peer-to-peer network. Problems in any part will not affect the overall operation, and each node saves a copy of the blockchain data. Therefore, the blockchain has built-in business continuity and has extremely high reliability and fault tolerance.
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Fifth, blockchain can improve the level of automation. Since all files or assets can be embodied in the form of codes or ledgers, smart contracts and automated transactions can be implemented on the blockchain by setting up data processing programs on the blockchain. For example, smart contracts can write a set of financial terms into the agreement to ensure automatic execution of the contract and payment of breach of contract.
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Sixth, blockchain can meet regulatory and auditing requirements. Records stored on the blockchain have the characteristics of transparency, traceability, and immutability. Any record, once written to the blockchain, is permanently saved and cannot be tampered with. Any transaction between two parties can be tracked and queried.
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In addition to the above positive effects on existing systems and business models, blockchain can also drive the birth of new business models. On the one hand, the characteristics of blockchain technology enable it to realize some business models that are difficult to achieve in a centralized model. On the other hand, blockchain greatly encourages innovation and collaboration in the whole society through the openness and collaboration of source code. Of course, blockchain will have many financial applications.Problems and challenges are also considered in the article in specific applications.

The working principle of blockchain technology is not difficult to understand. If we focus on the application research of specific blockchain technology, we can find that the working principle of this blockchain technology is ubiquitous.

H. Bitcoin What are "Blocks" in the Bitcoin network

Each block contains information about all recent transactions, a Nonce (random number) and the previous one The hash value of the block. When the entire block's SHA-256 hash is lower than the current target, it is marked as "resolved" (published and verified by multiple nodes). Usually it is difficult to reach the target with one hash, so the Nonce must be increased and the block must be re-hashed millions of times to reach the target. Bitcoin transactions are broadcast into the network via remitter, and all mining nodes (clients) collect the Bitcoins and add them to the block they are working on. If the transaction volume is large and exceeds the average transaction volume, the network will deduct a small transaction fee. The first transaction in each block is special: it creates new Bitcoins for the first person to mine a valid block. Other nodes (clients) will only accept the block if the transaction amount is correct. The number of Bitcoins generated per block is 50, which decreases by half every 210,000 blocks (approximately 4 years). The network attempts to create 6 blocks per hour. Every 2016 blocks (approximately two weeks), all Bitcoin clients compare this goal to the actual number of blocks created, modifying the block acquisition difficulty percentage to maintain this goal. The client considers the "longest" blockchain to be valid. The "length" of the entire blockchain refers to the chain with the most added difficulty, not the chain with the most blocks. This prevents someone from forging and creating a large number of low-difficulty blocks, tricking the network into accepting them as the "longest" chain. How many blocks have been collected so far? Click here to view the current number of blocks collected. What is the maximum number of blocks? There is no maximum number. Will blocks continue to be added to the end of the blockchain at a rate of one every 10 minutes? Even after all 21 million Bitcoins have been collected? [b] Yes. Blocks are used to prove that transactions existed at a specific time. After all Bitcoins have been mined, transactions will still occur. So whenever someone trades Bitcoin, blocks will still be created. [b] How long does it take to collect a valid block? No one can say accurately. There is a mining calculator that will tell you how long it might take. What does it mean if I calculate that the progress of a block has increased by 1%? There is no such thing as a 1% increase in progress. Each operation does not increase the progress. Calculate that your odds of getting Bitcoin after 24 hours are the same as when you started calculating. This is the same as if you spin 37 coins at the same time and make them all land heads. Every time you try, your chance of success isidentical.

I. What is the relationship between hashing and random numbers in the blockchain?

The hash value of the blockchain in Bitcoin transactions is a piece of code that can be used Query the number of confirmations of Bitcoin on the block, the handling fees paid by individuals, platforms, and wallets to miners, and you can also check the congestion of the network

J. How to understand blockchain and blockchain technology

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Blockchain technology uses mathematical methods to realize distributed accounting and solve trust issues, thereby completing decentralization and will have a profound impact in many fields such as communications, finance, Internet of Things, and government management.
Blockchain refers to a technical solution that collectively maintains a reliable database through decentralization and trustlessness. It is a technical method for all people to participate in accounting. The previous accounting methods were centralized and required a centralized intermediary, whether the intermediary was a traditional government, financial institution, notary agency or an emerging e-commerce platform or online payment platform.
In economics, information is sufficient. In fact, very large intermediaries exist precisely because of insufficient information. The existence of intermediaries increases transaction costs and raises transaction thresholds. Blockchain technology is essentially a large-scale collaboration tool. It uses pure technology to make direct value transfer possible for the first time, and continues the trend of decentralization and disintermediation of the Internet. Disintermediary blockchain technology will greatly subvert the information intermediary industry.
Blockchain technology is the basic technology for constructing the Bitcoin data structure and encrypted transmission of transaction information. This technology realizes the issuance and transaction of Bitcoin. The core of blockchain technology is that all currently participating nodes jointly maintain transactions and databases, making transactions based on cryptographic principles rather than trust, so that any two parties who reach an agreement can directly conduct payment transactions without the participation of a third party.
Technically speaking, a block is a data structure that records transactions, reflecting the flow of funds for a transaction. The blocks that have reached transactions in the system are connected together to form a main chain, and all nodes participating in the calculation record the main chain or part of the main chain.
A block contains the following three parts: transaction information, hash hash formed by the previous block and random number. Transaction information is the task data carried by the block, specifically including the private keys of both parties to the transaction, the number of transactions, the digital signature of electronic currency, etc.; the hash formed by the previous block is used to connect the blocks to realize the past The order of transactions; the random number is the core of the transaction. All nodes compete to calculate the answer to the random number. The node that gets the answer the fastest generates a new block and broadcasts it to all nodes for update, thus completing a transaction.