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Ⅰ You have to know the operating principles and development of blockchain!

1. Why is there innovation in blockchain?
The starting point of the first generation of the Internet is the TCP/IP protocol, which implements a unified format for peer-to-peer transmission of information by all nodes on the network. Open code. However, the impact of such an uncomplicated innovation on mankind is epoch-making. It has programmed, agreed, and enforced the basic values ​​required by a unified global market: "freedom, equality, and fraternity." Then the STMP email protocol, HTTP domain name protocol, etc. were derived, achieving low-cost and high-efficiency global information transmission in a decentralized manner. As Alibaba Vice President Gao Hongbing said:
"The Internet is to eliminate the (information) supply chain that has very low value and high cost - it is open, interconnected, peer-to-peer, globalized, and decentralized."
We know: The essence of the market is also decentralized. It automatically executes the decentralized agreement of "equivalent exchange". Just as Nobel Prize winner Ronald Coase summed up: "The market economy is based on two On the basis of deep cognition: admitting ignorance and tolerating uncertainty." Adam Smith also described the market as: "the invisible hand"! Therefore, the market must require the low-cost flow of information decentralization, and the Internet has adapted to the global Under the general climate formed by the unified market, it turned out to be.
However, the first generation of Internet decentralized solved the problem of low-cost and efficient transmission of information, but it did not solve the problem of credit of information. Therefore, what the second-generation Internet must break through is: how to establish global credit in a decentralized manner so that value transfer can be carried out at low cost and with high efficiency.
So what are the problems with the original centralized credit system? As we all know: centralized credit, such as the legal currencies of various countries, has different credit values, and the clearing systems are also incompatible, which adds a lot of cost to global trade. The current global credit system centered on the US dollar has a "Triffin Paradox" in its mechanism (the essence is that a country's legal currency cannot simultaneously resolve the conflict between its own economic interests and global economic needs). Therefore, in 2009, the Governor of the Central Bank of China, Zhou Ogawa called for the creation of a super-sovereign storage currency. In the same year, Satoshi Nakamoto disclosed the first-generation blockchain source code-"Bitcoin" online.
2. How does the blockchain system operate?
First of all, Satoshi Nakamoto knew very well that establishing a credit system for payment must solve the problem of preventing "duplicate payments", that is, no counterfeit currency can be created. The centralized credit system relies on state machinery to prevent counterfeit currency. What about "Bitcoin"? Satoshi Nakamoto's great innovation is to "timestamp" every transaction. There is a block (block: equivalent to a network account book) every ten minutes, and all network transactions for these ten minutes are correctly timestamped. The question is who will cover it? Satoshi Nakamoto did not assume that everyone on the Internet is Lei Feng. He agreed with Adam Smith: people in the market are greedy. He asked the so-called "miners" to compete for the accounting rights of each block for ten minutes. The rules of competition are correct.While keeping accounts, you need to solve the SHA256 problem. Whoever can prove that his computer has the fastest computing power (the so-called PROOF OF WORK mechanism) can compete for the legal accounting rights of these ten-minute blocks and get twenty-five Bitcoin rewards. This is the so-called "mining" process. It is actually a decentralized credit process that establishes a network-wide ledger - the blockchain. Therefore, the more essential function of miners is "bookkeepers"!
Satoshi Nakamoto is here In its Bitcoin white paper, the process of establishing this credit system is described in detail:
Step 1: In order for the entire network to recognize it as valid, each transaction must be broadcast to each node (node: that is, the miner);
The second step: Each miner node must correctly timestamp each transaction in these ten minutes and record it in that block;
The third step: Each miner node must Compete for the legal accounting rights of this ten-minute block by solving the SHA256 puzzle, and strive to get a reward of twenty-five bitcoins (fifty bitcoins every ten minutes for the first four years, decreasing by half every four years);< br>Step 4: If a miner node solves the SHA256 puzzle of these ten minutes, it will publish all the timestamped transactions recorded in its ten-minute blocks to the entire network, and they will be checked by other miner nodes in the entire network;< br>Step 5: Other miner nodes in the entire network check the correctness of the block accounting (because they are also stamping the accounting at the same time, but they have not competed for the legal block accounting rights, so there is no reward), there is no error Finally, they will compete for the next block after the legal block, thus forming a single chain of legal accounting blocks, which is the general ledger of the Bitcoin payment system - the blockchain.
Generally speaking, each transaction must undergo six block confirmations, that is, six ten-minute accounting, before it can finally be recognized as a legal transaction on the blockchain. The following is the accounting format of Bitcoin:
So the so-called "Bitcoin" is such a billing system: it includes the owner electronically signing with the private key and paying to the next owner, and then the entire network's "miners" "Time stamp the account and form a blockchain.
3. What are the innovations in Bitcoin’s blockchain finance?
Similar to gold, trying to establish decentralized credit on the global Internet may allow value to flow across the entire network at high speed and at low rates (currently each transfer The transfer rate is one ten thousandth);
The total amount of currency is agreed upon by the cryptographic protocol;
Compared to gold, digital currency is infinitely divisible;
The value of currency can be based on a large number of P2P transactions ;
Full transparency in financial management (every transaction can be traced on the blockchain).
Bitcoin’s blockchain-wide accounting system has established a market value of US$10 billion, the highest on the global Internet. Therefore, Wu Xiaoling, dean of Tsinghua PBC School of Finance, pointed out: The blockchain experiment established distributed credit, which is an upgraded version of Internet TCP/IP, upgrading from information transmission to value transmission;
4. Bitcoin’s blocks What are the inherent flaws of chain systems?
The Bitcoin blockchain system has been successful since it was open sourced on the Internet in 2009, but it also shows some inherent flaws that are difficult to overcome:
The total amount cannot change with the market situation and will inevitably rise and fall;
Mining is high-carbon. Only less than 1% of miners can compete for the accounting rights of less than ten minutes of blocks. More than 99% of other miners participating in the competition waste their computing power;
About 10% every year. Inflation has greatly increased the cost of the Bitcoin financial ecosystem and even threatened her survival;
As a decentralized self-organizing DAC system, the operating costs of the accounting and issuance functions are too high.
As a global payment system, its efficiency is far from meeting the actual requirements of global trade. The Bitcoin network currently confirms a maximum of 7 transactions per second. In comparison, Visa's network system can process 10,000 transactions per second at the fastest, and Alipay's record is 80,000 transactions per second on Singles' Day in 2014!
5. Block The development of chain technology 2.0:
As the 2.0 upgrade and development of blockchain, it first focuses on solving the high-carbon mining of Bitcoin accounting:
When we discuss how to overcome the high carbon of Bitcoin mining and accounting Professor Liu Taoxiong from the Tsinghua Institute of Economics pointed out that mining competition relies on computing power. In the end, only one company competes for the legal accounting rights, and the other 99% of the miner nodes are mined for nothing, which is a waste of resources. It is obviously unreasonable. If The whole network transparently knows the legal accounting rights of the next block, and it is randomly generated in the entire network, which eliminates the high carbon cost of competitive accounting! After hearing this, we all praised Professor Liu for his brilliant idea, because the second generation is now more successful. Coin NXT has this mechanism. Their white paper is called "Transparent Forging". However, the probability of the accounting rights going to someone is directly proportional to the NXT token holdings in each miner node wallet. This is called the proof of equity mechanism ( PROOF OF STOCK). Of course, this also triggered a debate about the unfairness of NXT’s distribution of tokens to early investment developers!
RIPPLE is a semi-decentralized blockchain solution that uses “trusted gateways” to conduct block operations. The credibility of chain accounting is based on the consensus ledger protocol that these gateways will not do evil at the same time.
The most ambitious attempt is Ethereum, which combines blockchain technology with Turing completeness, hoping to develop a basic platform that can support the construction of various blockchain systems in the future. The development of various credit currencies, digital assets, smart protocols and even financial derivatives. The system design is to unify blockchain accounting on the ETHERUM platform and be used by all developers. Maybe their official version will be released in the near future.
6. Possible applications of blockchain innovation in other fields:
Now, blockchain’s attempts to establish decentralized credit are no longer limited to the financial world, but have attracted attention from all fields of society, especially in At present, some of China’s central credits, such as the “Red Cross Society”, are in a state of “collapse”.Blockchain can provide a new way of thinking and technical options for social management. Here are some new developments and related discussions we have learned about:
The combination of blockchain and the Internet of Things unifies digital assets and atomic assets. Eradicate the difference between consumer assets and cash assets, expand public credit, and accelerate value circulation; (IBM-Samsung)
Establish an intellectual property protection system on the blockchain, keep accounts of the use of intellectual property across the entire network, and establish global advertising Market;
Whether blockchain can provide technical support for the issuance of protocol-based cryptographic currencies in emerging economies along the Belt and Road Initiative;
Blockchain + cloud computing can develop into decentralized self-media and community systems;< br>Blockchain can build a decentralized equity crowdfunding system, allowing innovative projects to enter the circulation field in advance;
Blockchain can develop a fully transparent financial management system;
Blockchain supports the establishment of a global Centralized corporate organization.
In short, in this era when credit has become a scarce resource, the technological innovation of blockchain, as a distributed credit model, provides new opportunities for finance, social management, talent evaluation and decentralized organization construction in the global market. All provide a broad development prospect.

II Does anyone know how to make a directed acyclic graph (DAG) using a program, and how to apply it to economic empirical studies

Let’s talk about the area Blockchain is still immature and has various problems, such as slow processing speed, high handling fees, security risks, etc. These are the most intuitive experiences for users, and the experience is not very good. There is another problem with blockchain, and that is the problem of high concurrency.
What is the problem of high concurrency? Let’s briefly talk about it. High concurrency is a problem in the computer field. Simply put, the problem of high concurrency is that the system cannot run multiple tasks smoothly at the same time.
Many tasks are running at the same time, and a large number of users come in. The system cannot bear so many tasks, and high concurrency problems will occur, and your system will be stuck. Just like during the Spring Festival travel rush, the 12306 system is always stuck. Yes, it may be caused by high concurrency issues.
The traditional Internet still has high concurrency problems, and the blockchain network naturally also has this problem. After all, the maturity level of the blockchain is still far behind the traditional Internet. However, without a safe, reliable and efficient public chain, the development of the entire blockchain industry will be severely restricted, and the implementation of applications will be empty talk.
In this context, DAG technology was proposed. The full name of DAG is "Directed Acyclic Graph", which is translated into Chinese as "Directed Acyclic Graph".
What is DAG directed acyclic graph, and what role does it play? Let’s explain it below.
1. DAG: a new type of data structure
DAG, the Chinese name is "directed acyclic graph", literally, "directed" means that it has a direction,
"No ring" means itThere is no loop and cannot form a closed loop. Therefore, DAG is actually a new type of data structure. This data structure has direction and cannot form a closed loop.
In terms of traditional blocks, we always use "block" as the unit, and a block often contains multiple transaction information. In DAG, there is no concept of blocks, but "units" are used as units. Each unit records the transactions of a single user. The units are not blocks, but transactions. In this way, It can save the time of packaging and producing blocks.
To put it simply, the biggest difference between blockchain and DAG directed acyclic graph is that blockchain is a distributed ledger that stores and verifies transactions one block after another, while DAG stores and verifies each transaction. Transactions are viewed as a block, and each transaction can be linked to multiple previous transactions for verification.
2. The working principle of DAG
In traditional blockchains, take Bitcoin for example, it has a single-chain structure, and blocks are arranged in the order of timestamps. (Figure 1), the data is recorded on a main chain. To use an inappropriate metaphor, this
"single chain" structure is a chain arranged in one line.
The blockchain only has a single chain, and it cannot be executed concurrently if the blocks are packaged. New blocks will be added to the original longest chain, and all nodes will follow the longest chain and continue to spread infinitely in the order of timestamps. For DAG, each newly added unit is not only added to one unit of the longest chain, but also to all previous units (Figure 2).
For example: Suppose I publish a new transaction. At this time, the DAG structure already has 2 valid transaction units, then my transaction unit will actively link to the previous 2 at the same time to verify and Confirm until it is linked to the genesis unit, and the hash of the previous unit will be included in its own unit.
In other words, if you want to make a transaction, you must verify the previous transaction, specifically verify several transactions, and proceed according to different rules. This verification method allows DAG to write many transactions asynchronously and concurrently, and ultimately forms a topological tree structure, which greatly improves scalability.
According to the DAG directed acyclic graph, every transaction directly participates in maintaining the entire network. When a transaction is initiated, it is directly broadcast to the entire network, skipping the block packaging stage of miners. This saves the time of packaging transactions and producing blocks, and improves the efficiency of blockchain transaction processing.
As time goes by, the blockchains of all transactions are connected to each other to form a graph structure. If you want to change the data, it is not just a matter of a few blocks, but the data change of the entire block graph. . In comparison, the DAG model is more complex and more difficult to change.
To summarize, DAG, as a new type of decentralized data structure, is a type of generalized blockchain and has decentralized attributes, but the difference between the two is:
District Block chain componentsIt is Block (block), and the DAG component unit is TX (transaction).
Blockchain is single-threaded, and DAG is multi-threaded.
All transaction records in the blockchain are recorded in the same block, and each DAG transaction is recorded separately in each transaction.
Blockchain requires miners, DAG does not require miners.
3. Representative of DAG: IOTA
The most famous current representative project of DAG is undoubtedly IOTA. It can be said that it is precisely because the currency IOTA rushed into the fourth place in the market value rankings in the second half of 2017 that people truly realized its underlying technology: DAG directed acyclic graph.
IOTA proposed the concept of "tangle" based on the DAG directed acyclic graph. In IOTA, there is no concept of block, and the smallest unit of consensus is a transaction. Each transaction will reference the hashes of the two past transaction records, so that the previous transaction will prove the legitimacy of the past two transactions and indirectly prove the legitimacy of all previous transactions. In this way, a small number of nodes such as miners in traditional blockchains are no longer needed to verify transactions and package blocks, thus improving efficiency and saving transaction costs.
4. Current situation of DAG
Although theoretically, DAG directed acyclic graph can make up for some shortcomings of traditional blockchain, it is not mature yet and has been applied to the digital currency field for a relatively short time. , still relatively young.
It has not taken 10 years to verify the security of the entire system like Bitcoin, nor has it achieved a wide range of application scenarios like Ethereum. However, some voices are now proposing to adopt the "traditional blockchain + DAG" data structure, but there are no very outstanding cases yet, so I won't go into details here.
To summarize, in this section we introduce the derivative technology of blockchain: DAG directed acyclic graph, which is a brand-new data structure that can significantly improve the efficiency and concurrency of blockchain processing transactions. improvement.

Ⅲ 108 knowledge points for getting started with blockchain

1. What is blockchain

Combine the information of multiple transactions and the information indicating the block The information is packaged and put 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. WhatWhat 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, a large amount of traffic The influx of data may cause the website to fail to function properly, resulting in losses. 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 data structure for storing data. The bottom layer is the original data contained in all blocks, and the upper layer is each The hash value of a block, the hash of this layer is combined in pairs to generate a new hash value, forming a new layer, and then upwards 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 blocks is the same, only the hash values ​​of the blocks are different), and then two chains are forked from these two blocks. Whoever generates 6 blocks first from these two links 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

23 replay attack

The hacker resends the message that has been sent to the server. 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. aboveprocess. 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 syntax of the transaction is correct, whether the transaction amount is greater than 0, 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 secondQuantity TPS

That is throughput, tps refers to the number of transactions that 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. With the development of the company, the company's own chain development has been 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. Bull (long)

The buyer believes that the currency price will rise in the future and buys Input currency, wait for the currency price to rise, 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 borrow currency from the trading platform) sell it, and after the currency price drops, buy it at a low price to take profits

53. Open a position

Buy virtual currencies such as Bitcoin

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54. Cover the position

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

55. Full position

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Buy all the funds at once for a certain virtual currency

56. Rebound

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

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57. Consolidation (sideways)

The price fluctuation is small and the currency price is stable

58. The currency price declines

The currency price slowly declines

59. Diving (waterfall)

The currency price fell rapidly and to a large extent

60. Cutting meat

After buying Bitcoin , the currency price fell, and Bitcoin was sold at a loss to avoid further losses. 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 raise the price of the currency, inducing the bulls to think that the price of the currency will rise and buy one after another. As a result, the short sellers sell Bitcoin.Suppressing the price of the currency, locking up the bulls

67. Short baiting

After the bulls bought Bitcoin, they deliberately suppressed the price of the currency, making the short sellers think that the price of the currency would fall, and they sold them one after another. As a result, I fell into the trap of bulls

68. What is NFT

The full name of NFT is "Non-Fungible Tokens", which means non-fungible tokens. To put it simply, currency is an indivisible copyright certificate on the blockchain. It 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 and improve 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 using traditional equipment (CPU, GPU).As the chips get bigger, people develop 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, timestamps prove when something happened on the blockchain and 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, such as WiWindows 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/

Non-small account: 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 < /p>

85. Blockchain Explorer

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 and buy reliable ladders

90. Platform currency

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

91. Bull market, 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, and AI is the new productionPower, blockchain is a 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. contract trading buyThe object of sale is a standardized contract formulated by the exchange. The exchange stipulates standardized information such as product type, trading 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)

p>

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

IV What is "blockchain"

Blockchain technology is a way to decentralize and eliminate trust. Techniques for jointly maintaining reliable databases. Four keywords can be used to describe blockchain technology: trust reduction, decentralization, collective maintenance and reliable database.

When we talk about the concept of "blockchain", Bitcoin is definitely a topic that will not be ignored. In recent years, Bitcoin has begun to enter the public eye, especially in 2017, which has continued to skyrocket throughout the year, making many people aware of this emerging thing.

Blockchain is actually the underlying technology of Bitcoin. Bitcoin exists because people on the Internet who don’t know each other can move and trade digital currency through the Bitcoin network. And this is driven by blockchain technology. All Bitcoin transactions are recorded on the blockchain ledger. To a certain extent, in the application of Bitcoin, the blockchain plays the role of the underlying database of the bank transaction system. Both are for "keeping accounts". Although it is not very prudent to refer to the blockchain directly as a "database", for the sake of ease of understanding, let's temporarily call it a decentralized, shared and encrypted database. If described in professional terms, blockchain is a distributed ledger technology.

Blockchain can usually be divided into the following types:

1. Public blockchain. Anyone can access data on a public blockchain, and anyone can issue transactions waiting to be written to the blockchain. Participants in the consensus process (corresponding to miners in Bitcoin at the time) maintain the security of the database through cryptography and built-in economic incentives.

2. Collaborative blockchain. The nodes participating in the blockchain arePre-selected, nodes are likely to have good network connections. Other consensus algorithms other than proof-of-work can be used on such a blockchain. For example, a blockchain has been established among a hundred financial institutions, and it is stipulated that more than two-thirds of the institutions must agree to reach a consensus. The data on such a blockchain can be either public or shared internally by these node participants.

3. Private blockchain. The participating nodes are only individual users, and the access and use of data are subject to strict permission management. Most of the internally used blockchain technologies announced by some financial institutions recently are vague and may fall into this range.

The blockchain is a public ledger. There is no centralized hardware or management organization. Anyone can automatically verify the authenticity of the ledger and easily discover whether the ledger has been tampered with by others.

In a word, the blockchain is a public ledger that can be verified by everyone.

The concept of being verifiable by everyone is crucial to blockchain.

Bitcoin uses the blockchain to record all transactions, so anyone knows the number of Bitcoins on each account.

So, as a publicly verifiable ledger, what are some use cases for blockchain?

In fact, there are many use cases that can be thought of. Blockchain is suitable for any data that can be recorded on a public ledger. Here are 4 examples:

1. Decentralized domain name server, namely domain currency. The domain name server is actually a ledger that records domain names.

2. Trustless public key encryption, such as https that discards unreliable certification authorities.

3. Ownership records, truthfully record the items and their corresponding owners.

4. Contracts and performance guarantees, the account book truthfully records the parties to the contract and saves the contract text.

But don’t forget that blockchain also has a very important component.

The ledger recorded using blockchain technology will always be updated. New data such as transactions, domain name inputs, records and contracts will be converted into hash values ​​of the same length by the hash algorithm and saved. However, hashing algorithms are not only not free but also very expensive.

Therefore, the ledger itself needs to have a recognition system to recognize the person who enters the block hash value.

In Bitcoin, this system is called mining and is rooted in the Bitcoin protocol. Bitcoin miners use a hash algorithm to convert transactions waiting for verification into hash values, and charge a certain amount of Bitcoin as a service fee.

Therefore, for non-monetary use cases, blockchain needs to find a way to bear the high cost of hashing algorithms.

I would like to remind everyone that my answer mainly focuses on the possible applications of blockchain technology.Among the use cases, not all aspects of blockchain are covered, such as why hashing algorithms are so expensive. I'm sure you can find a lot of detailed information about Bitcoin and other blockchain applications online.

Supplement

Although blockchain technology has many advantages, there are still some less than ideal use cases. For example, there is no way to convert Bitcoin into any national currency; a ledger with billions of data entries would take up space and be impractical.

Bitcoin has shown the world that blockchain technology is feasible in principle, and people are also trying to solve these increasingly prominent problems, such as technological transformation of Bitcoin or the introduction of a completely Different blockchain technologies. I think the following two methods are worth trying: one is to split the ledger according to certain standards such as the payer address, and the other is to introduce a main blockchain to verify the sub-blockchain. Blockchain technology is ever-changing and dazzling, and it’s unknown whether someone is already making such an attempt. But Bitcoin is still the world's first currency blockchain, what others call a cryptocurrency.

Whether in the technology circle or the financial circle, blockchain has become the hottest word, no one. Blockchain has core advantages such as decentralization and trustlessness, and can perfectly solve problems such as information asymmetry, high transaction costs, and trust of strangers in the development of the sharing economy, making "individual economy" possible. Based on this, blockchain technology is considered to be the core technology that has the greatest potential to trigger the fifth wave of disruptive revolution after steam engines, electricity, information and Internet technology.

In this context, a blockchain craze was born in society, and everyone praised it overwhelmingly. Dialectics tells us that everything has flaws, and only by seeing the pros and cons of things can we make rational decisions. Therefore, in this article, Xue Hongyan (Hong Yanweiyu), a senior researcher at Suning Financial Research Institute, focuses on pouring some cold water on the blockchain.

| What is Blockchain

Blockchain, English Blockchain, has a rather mysterious technological flavor in its name, and can be simply broken down into "data blocks" and "links". Each data block contains all the information exchange data of the system within a certain period of time, and is encrypted using cryptographic methods; the link means that each block has a link relationship with the next block, thus forming a blockchain.

It is generally believed that blockchain has two major characteristics: decentralization and trustlessness. A brief introduction is as follows:

Since each block contains all the information exchange data of the system within a specific period of time, Therefore, each block is equal, and the damage of a single block does not affect the security of the entire system, so the blockchain has decentralized characteristics.

Similarly, since each block contains all the information of the system, the authenticity of the information isIt can be cross-verified. Only by breaking through more than 51% of the nodes can the information be tampered with. In a large enough blockchain system, the cost is extremely high. It can be considered that the information in the blockchain is true, so the blockchain has the ability to Trust characteristics.

Most people’s understanding of blockchain begins with Bitcoin. The relationship between the two is that blockchain is the underlying technology and concept, and Bitcoin is only the most popular application of blockchain at present. .

Maybe the above is not popular enough. Finally, let me summarize, what do you think the blockchain is? Is it a disruptive new technology? NO! According to Xue Hongyan (Hong Yanweiyu), a senior researcher at Suning Financial Research Institute, blockchain is not so much a new technology as it is a new ideological concept. The information encryption and other technologies included in the blockchain have been around for a long time, and it is more of a conceptual innovation. This is also the reason why the blockchain has a huge impact. New technologies will be surpassed sooner or later, ranging from one or two years to four to five years; only innovative ideas have enough energy to affect all aspects of the economy and society.

| Blockchain is expected to change the underlying rules of the financial system

In applications in the financial field, blockchain will change the transaction process and record keeping methods, thus significantly reducing transaction costs. It has significantly improved efficiency and is considered to have a broad market environment in digital currency, cross-border payment and clearing, bill trading, securities issuance and trading, property rights transactions, customer credit reporting, anti-fraud, and anti-money laundering.

Such a good technology is naturally sought after by everyone. Like many traditional financial people, Hong Yanweiyu resisted it at first, thinking that this thing was not that great, and did not do any research specifically. Later, as the research on financial technology gradually deepened, it was discovered that blockchain was an obstacle that could not be bypassed, because whether it was robo-advisory, big data risk control or online lending, they were only technological innovations at the financial business level and risk control level. It has not penetrated the bottom layer of the financial system. What is the underlying layer of the financial system? Naturally, it is payment and settlement, transaction rules and system interaction. What the blockchain changes is precisely the underlying rules.

Therefore, throughout the world, financial institutions are the most active in researching blockchain. If nothing else, they are really afraid. After the decentralization and trustless features of the blockchain are fully utilized, what else will the intermediaries of financial institutions do? It is estimated that this is also the first feeling of many people who have a preliminary understanding of blockchain.

In this article, Hong Yanweiyu focuses on pouring cold water on this view.

| Subverting the financial system, blockchain still faces two mountains

Marxist dialectics tells us that everything has two sides. The more prominent the advantages, the more obvious the flaws. It’s just the perspective. Just different. The two major problems with blockchain subverting the financial system lie precisely in the two major advantages of decentralization and trustlessness.

First, let’s talk about decentralization. First of all, we must make it clear that centralization must meanIs it inefficient? Of course not. Within a specific scope, the concentration of resources brought about by centralization can greatly improve efficiency. This is also the reason why human beings evolve from individuals to villages to tribes and then to countries in the process of evolution. Take UnionPay as an example. UnionPay is the clearing and settlement center for the domestic banking industry. After UnionPay is established, each bank only needs to connect with UnionPay to realize transactions with all banks. If it is decentralized, without UnionPay, each bank will need to When communicating with all counterparties, which one is more efficient? Therefore, there is no need to beat centralization to death with a stick. The decentralization feature of blockchain is destined to only play a role in specific fields (that is, fields that are not suitable for centralization). How can it subvert everything?

Furthermore, it is a matter of trust. There is nothing wrong with detrusting itself, but the technical logic behind it is deeply flawed. Blockchain relies on universal accounting to achieve trustlessness, that is, all transaction information is retained in each block for system cross-verification to identify authenticity. Here comes the problem. Each block retains all transaction information. There is no problem on a small blockchain. However, as more and more information is added, it will inevitably lead to an explosive growth of transaction information and will also bring information. Dramatic increase in storage costs. At the same time, the greater the amount of information, the longer cross-validation takes and the lower the efficiency. Therefore, the blockchain solves the trust problem, but it brings about rising costs and declining efficiency.

Nothing in the world is perfect, and the same is true for blockchain.

As a conclusion, Hongyanweiyu wants to clarify that blockchain, as a conceptual innovation, does have great value and can also have a disruptive impact in specific fields. However, the current one-sided thinking about blockchain is problematic. Eastern wisdom tells us that "the most brilliant and the golden mean", in the face of anything, it is wisest to maintain the golden mean.

(Text/Xue Hongyan, senior researcher at Suning Financial Research Institute; WeChat public account: Hongyan Weiyu)

As early as a few years ago, the word "mining" came with Bitcoin is well known for its popularity. Many people know about Bitcoin first and then the blockchain, and they even don’t know about the blockchain yet. By definition, blockchain is a series of data blocks generated using cryptographic methods. Each data block contains information about a Bitcoin network transaction, which is used to verify the validity (anti-counterfeiting) and generation of its information. Next block.

I am not a computer technology expert. The following introduction to blockchain comes from reading and comments from expert friends and is for reference only.

If you want to use one word to explain blockchain, it is: distributed accounting.

To understand what this word means, you need to first understand that traditional accounting has a center. For example, in a bank, when you withdraw money from a bank deposit or lend money to others through the bank, the bank is the center, and all these transactions are based on the bank's credit. What if the bank cheats? Or worse, the countryWhat about cheating? The Kuomintang's indiscriminate issuance of gold yuan coupons at the end of its rule in mainland China, as well as the hyperinflation in Weimar Germany and Zimbabwe, which made the currency less valuable than toilet paper, are very famous examples.

Golden Yuan Coupons

This is the problem that blockchain is aimed at. They believe that decentralized accounting is non-modifiable and non-repudiable. How to achieve decentralized accounting? The basic idea is that all users store all transaction records, making it very difficult to illegally modify the ledger through mathematical methods. In this way, the reliability of the ledger is guaranteed.

Specifically, all users exhaustively enumerate random number variables, and the first user to obtain a specific required hash function value (Hash) will have the right to record this round of transactions and obtain the corresponding Bitcoins award. It is transmitted in the form of data blocks, and the data blocks are connected into a chain by appending at the end, so it is called a block chain.

After listening to the introduction, you may feel that this idea is interesting, but it is not as exciting or revolutionary as advertised. Your feeling is right. In fact, the basic logic of blockchain has some unavoidable problems.

For example, the current size of the complete Bitcoin public ledger has exceeded 150 G, and is rapidly increasing at a rate of tens of G per year - just to support 5 million users and 30 million transactions per year. If its processing volume is one day comparable to that of Alipay, the size of the Bitcoin ledger will increase by more than 500 terabytes per year. This is equivalent to backing up the Alipay server's storage data on all users' personal computers. Do you think this is a good idea?

For another example, in the traditional banking system, if you lose your password, it is no big deal. Just report it to the system in time, and your wealth will not disappear. But in the blockchain system, if you lose your password, it will be a huge trouble, and your currency will not be recovered. Not happy? Is it surprising?

Blockchain is a new application model of computer technologies such as distributed data storage, point-to-point transmission, consensus mechanism, and encryption algorithms. The so-called consensus mechanism is a mathematical algorithm that establishes trust and obtains rights and interests between different nodes in the blockchain system

In layman’s terms, it is playing mahjong. Four people can take turns to be the banker, and each other can shoot four people. They all have their own ledger records, but if you want to modify the ledger, you must have more than 50% of the modification rights, so the cost of cheating on the ledger is very high.

In the future, blockchain will be used more in finance to combat money laundering and fraud, because all information can be traced, and in culture it can be used for copyright protection, etc.

< /p>

I have seen many people’s explanations of blockchain using official rhetoric, and some may not even explain it themselves.None of them are clear. I will explain the blockchain in vernacular below to ensure that everyone can understand it.

What is blockchain? Let me give an analogy. In 50 years, you can buy an electric fan from the supermarket. This electric fan will automatically mine coins for you when it is blowing. You can mine coins automatically while using the electric fan. When you use this electric fan, When the fan breaks down, you can use the mined coins to repair the electric fan. Of course, you can also use the mined coins to buy a new electric fan. Many people think wrongly! Wouldn’t the profits of merchants be less? Let me tell you about a certain brand. When the products of this brand are sold to you, the products themselves may even be sold to you at a loss. However, once the number of users becomes large and the users become more sticky, they can be paid through membership fees or service fees. Such small fees or other ways to make profits. Just like this, the mined coins can be purchased and repaired. Although the merchant's profit may be reduced, the merchant has gained more users and greater user stickiness. By this time, it only takes a minute for the merchant to make money.

And the electric fan you bought is equivalent to winding it up for you. What is winding up? If you put your electric fan on the street now, and 10 people come to snatch it, you have no way to prove that the ownership of this electric fan is yours. Once you put it on the chain, it is equivalent to being tied to you. Once it’s settled, you can prove it.

Therefore, the essence of blockchain is to help make people’s lives more convenient. It is equivalent to upgrading on the basis of the Internet, making it safer and more convenient. This is blockchain! It's that simple.

The security of the blockchain is reflected in its irreversibility and the data cannot be tampered with. We all know that in today's society, any data can be modified and conquered by hackers, but the data in the blockchain is impossible to change. Once generated, it cannot be modified unless all users in the blockchain work together. Agree to modify the data, but this is unlikely to happen.

At present, the blockchain is still very immature, just like the Internet bubble burst in 2000. When the bubble bursts, a truly valuable blockchain Internet will be hatched. company.

The wheel of history will not go backwards. Many people are unwilling to accept blockchain. Just like telling you that you can shop online 20 years ago, this is the same ridiculous thing. Time will eventually prove it. .

1. The main function of blockchain is to store information. Any information that needs to be saved can be written to the blockchain and read from it, so it is a database.

2. Anyone can set up a server, join the blockchain network and become a node. In the world of blockchain, there is no central node. Every node is equal and stores the entire data.library. You can write/read data to any node, because all nodes will eventually be synchronized to ensure that the blockchain is consistent.

3. Everyone works on the same blockchain, everyone publicly shares the current state of the blockchain, everyone agrees on the rules for new data submission and tampering with the blockchain is prohibited. It is difficult to operate in terms of computing power.

If we assume that the database is a ledger, reading and writing the database is an accounting behavior:

Anyone can verify this public ledger, but there is no single The user can control it. Participants in the blockchain system will jointly maintain the update of the ledger: it can only be modified according to strict rules and consensus, and there is a very exquisite design behind this.

(1) Accounting, the system will find the person with the fastest and best accounting within a period of time, let this person do the accounting, and then broadcast the information on this page of the account book to everyone else on the entire network. node, which is equivalent to changing the database record; (consensus mechanism, cryptography)

(2) Verification, other valid nodes in the entire network check the correctness of the block accounting, and stamp the time Stamp to confirm that the block is legal; (timestamp, mathematics)

(3) Form a single chain, that is, compete for the next block after the previous legal block; (smart contract, encryption technology)

p>

(4) Storage, the account book is stored in blocks. As transactions increase, new data blocks will be appended to the existing chain to form a chain structure; (distributed structure, information technology) < /p>

(5) Backup, every participating trader is a node of the block network, and each node has a complete backup of the public account book, which is a distributed ledger.

Features

1. The blockchain has no administrator and is completely centerless. It is precisely because it cannot be managed that the blockchain cannot be controlled. Without an administrator, everyone can write data into it. In order to ensure the trustworthiness of the data: the technology of blockchain makes it impossible to tamper with the data once it is written.

2. Close to zero trust cost.

The cycle time required for Internet companies to build their credit is extremely long. For example, Taobao often takes several years to build its credit. In the blockchain, everyone trusts the code, algorithm and rules, so the cost of trust is extremely low.

3. The marginal cost of constructing and trading assets approaches zero.

If traditional assets are to be used for trading, they need to rely heavily on third parties, such as investment banks, banks, securities firms, etc., for packaging and endorsement, and the fees and thresholds are extremely high. With blockchain, these will not be a problem, and the cost is extremely low.

The value transfer attribute of the blockchain also naturally solves the payment problem, and has the genes to support global payments.

Blockchain, simply put, it is the underlying technology that supports ICO (virtual currency). The popular Bitcoin is an application of ICO. In other words, the connotation of blockchain is richer, and its main features are:

1. Blockchain is equivalent to digital trust. Both parties to the transaction can independently enter into digital contracts, and companies providing blockchain services are equivalent to Digital trust company;

2. The purpose and characteristics of blockchain are "3 de-intermediaries" - de-intermediation, de-currency, de-sovereignty; yes

3. Bitcoin is An application of blockchain, Bitcoin is a cryptocurrency, and all blockchains apply digital encryption technology;

4. The "3 Go" feature is targeted at the financial industry, and only when high frequency is required Blockchain is only needed in the financial field of transactions;

5. Large platforms with a user base are more suitable for applying blockchain, and small companies’ participation is of little value, so Zuckerberg’s 2018 New Year’s wish includes To study digital cryptocurrency. Kodak also launched a digital currency, sending its stock price soaring.

Furthermore, when it comes to Bitcoin, it can be cashed out and exchanged into the currencies of most countries. Users can use Bitcoin to purchase some virtual items, and they can also use Bitcoin to purchase real-life items. In this sense, Bitcoin is similar to the world's currency, close to gold.

Peter Thiel, co-founder of PayPal and an early investor in Facebook, believes that Bitcoin is "undervalued" by people and compares it to gold. He said: "If one day Bitcoin becomes the online equivalent of gold, then it will have room for appreciation."

But on January 3, the "People's Daily" published an article saying, "Whether it is from The increase can still be seen from the value of the currency itself. There is a bubble in the price of Bitcoin. This is an issue that needs no discussion." Data show that in the past 2017, Bitcoin has skyrocketed and plummeted: within a year, the price skyrocketed about 20 times, and in one day It fell more than 40% within the period.

Indeed, Bitcoin has risks. However, blockchain with richer connotations obviously still has greater room for development.

Last night, screenshots of Xu Xiaoping, founder of ZhenFund, encouraging the embrace of the blockchain revolution in an internal group were posted online. In his view, the blockchain revolution has indeed arrived. “I strongly encourage everyone internally to embrace the blockchain revolution and learn blockchain technology. This is my understanding after long-term observation and thinking. I feel responsible to tell our entrepreneurs. I don’t want my understanding of blockchain The views have been misunderstood as views on ICO."

However, in the context of Internet companies and investment institutions collectively entering the market, the government will definitely take measures.

Recently, the U.S. Securities and Exchange Commission (SEC) has expressed concerns about this and shelved the plans of two U.S. companies to launch Bitcoin exchange-traded funds (ETFs).proposal.

In fact, this is only a matter of time. Because the "three-go" feature of blockchain is inherently contradictory to government centralization.

IV Blockchain technology concept

Blockchain technology concept

Blockchain technology concept, nowadays, blockchain Chain has become an area of ​​concern for most people, and many companies have already studied the technology in depth. However, there are still people who don’t know much about it. Here I will share an article about the concept of blockchain technology.

Blockchain technology concept 1

Basic concepts and working principles of blockchain

1. Basic concepts

Blockchain is a distributed data storage, point-to-point New application models of computer technologies such as transmission, consensus mechanisms, and encryption algorithms. The so-called consensus mechanism is a mathematical algorithm that establishes trust and obtains rights and interests between different nodes in the blockchain system.

Blockchain is an important concept of Bitcoin. It is essentially a decentralized database and serves as the underlying technology of Bitcoin. The blockchain is a series of data blocks generated using cryptographic methods. Each data block contains information about a Bitcoin network transaction, which is used to verify the validity of the information, prevent counterfeiting, and generate the next block.

In a narrow sense, blockchain is a chained data structure that combines data blocks in a sequential manner in chronological order, and is cryptographically guaranteed to be non-tamperable and non-tamperable. Fake distributed ledger.

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

2. Working principle

The blockchain system consists of data layer, network layer, consensus layer, incentive layer, contract layer and application layer. Among them, the data layer encapsulates the underlying data blocks and related basic data and basic algorithms such as data encryption and timestamps; the network layer includes distributed networking mechanisms, data dissemination mechanisms, and data verification mechanisms; the consensus layer mainly encapsulates network nodes Various consensus algorithms; the incentive layer integrates economic factors into the blockchain technology system, mainly including the issuance mechanism and distribution mechanism of economic incentives; the contract layer mainly encapsulates various scripts, algorithms and smart contracts, and is the core of the blockchain The basis of programmable features; the application layer encapsulates various application scenarios and cases of the blockchain. In this model, the chain block structure based on timestamps, the consensus mechanism of distributed nodes, economic incentives based on consensus computing power, and flexible programmable smart contracts are the most representative innovations of blockchain technology.

Blockchain mainly solves the trust and security issues of transactions, so it proposes four technological innovations to address this issue:

1. Distributed ledger, which means that transaction accounting is performed by multiple accounts distributed in different places. The nodes work together, and each node records a complete account, so they can all participate in supervising the legality of the transaction and can also jointly testify for it.

Different from traditional distributed storage, the uniqueness of blockchain distributed storage is mainly reflected in two aspects: First, each node of the blockchain stores complete data according to the block chain structure. For data, traditional distributed storage generally divides the data into multiple parts for storage according to certain rules. Second, the storage of each node in the blockchain is independent and of equal status, relying on the consensus mechanism to ensure storage consistency, while traditional distributed storage generally synchronizes data to other backup nodes through the central node. [8]

No node can record ledger data independently, thus avoiding the possibility of a single bookkeeper being controlled or bribed to record false accounts. Also because there are enough accounting nodes, theoretically speaking, the accounts will not be lost unless all nodes are destroyed, thereby ensuring the security of the accounting data.

2. Asymmetric encryption and authorization technology. Transaction information stored on the blockchain is public, but account identity information is highly encrypted and can only be accessed with authorization from the data owner. , thus ensuring data security and personal privacy.

3. The consensus mechanism is how all accounting nodes reach a consensus to determine the validity of a record. This is both a means of identification and a means of preventing tampering. Blockchain proposes four different consensus mechanisms, which are suitable for different application scenarios and strike a balance between efficiency and security.

The consensus mechanism of the blockchain has the characteristics of "the minority obeys the majority" and "everyone is equal". "The minority obeys the majority" does not entirely refer to the number of nodes, but can also be the computing power and the number of shares. Or other characteristic quantities that the computer can compare. "Everyone is equal" means that when a node meets the conditions, all nodes have the right to give priority to the consensus result, which will be directly recognized by other nodes and may eventually become the final consensus result. Taking Bitcoin as an example, it uses proof of work. Only when more than 51% of the accounting nodes in the entire network are controlled, it is possible to forge a non-existent record. When there are enough nodes joining the blockchain, this is basically impossible, thus eliminating the possibility of fraud.

4. Smart contracts. Smart contracts are based on these trustworthy and non-tamperable data. Some predefined rules and terms can be automatically executed. Take insurance as an example. If everyone's information, including medical information and risk occurrence information, is true and trustworthy, it will be easy to implement automated claims settlement in some standardized insurance products.

3. Others

InternetWhat is exchanged is information, and what the blockchain exchanges is value. Human history and the history of the Internet can be understood in eight words: if they are divided for a long time, they must be combined. For a long time, they must be combined. In the era of long-term separation, all network information is scattered on the Internet. It is very difficult for everyone to mine information. At this time, platforms such as Google and Facebook will appear. , the only thing it does is recombine all our information. In the Internet era, what the monopoly giants reorganize is information, rather than generating their own information. The information generated is entirely our own. Once the information is reorganized, a new monopoly giant will emerge, so it will be an era of long-lasting separation. Now, due to the emergence of blockchain technology, it has entered an era of integration and division. It is a new multi-centralization. After the new multi-centralization, new value will be generated. These data will be in our own hands, and personal data will generate value. It belongs to oneself. This is the most exciting era of this era.

What is the value of blockchain? A low-cost mechanism to establish trust, establish data rights, and resolve data property rights.

At present, blockchain technology continues to develop, including the current development of single chains to multi-chains, and the technology can be further expanded. I think there may still be disruptions in the future, especially in transactions and other aspects. , especially many disruptive scenarios for existing industries.

The essence of blockchain is to establish trusted information exchange on untrustworthy networks.

One Belt, One Road + One Chain. The bigger thing about blockchain is not to create trust, but to allow trust to be transmitted losslessly, reducing the friction cost of society as a whole, thereby improving the overall efficiency.

Now the blockchain itself is still in its initial stage, so it includes the information transmission and encryption of the blockchain. Quantum encryption and other encryption appear in this process, which actually attacks the encryption algorithm used by the blockchain itself. This phenomenon also occurs from time to time. Including blockchain is also a recognition of assets, a recognition of digital assets, but now many of us use cryptographic algorithms, or as the key for us to decrypt, but if you forget the password, it is very likely that your current assets will be lost. If you lose them, you won't be able to get back your original assets. Therefore, there are still some hidden dangers in asset management, including information transmission and some security aspects. Of course, from a technical perspective, the processing speed of our blockchain itself, or its scalability, is because from the perspective of the working mechanism, the entire ledger must be copied to all participants, so in the blockchain Its operational efficiency and scalability are still relatively limited. We feel that these still need further development in terms of technology.

The underlying technologies of the blockchain platform also form blockchain wallets, blockchain browsers, node elections, mining machines, mining pools, development components, development modules, technical communities and project communities. and a series of ecosystems. The perfection of these ecosystems directly determines the efficiency and effectiveness of the underlying platform of the blockchain.

4. Mundell’s Impossible Triangle

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Decentralization, efficiency, and security are impossible to achieve the ultimate in all three at the same time.

Blockchain technology concept 2

The essence of blockchain is a distributed accounting technology, as opposed to centralized accounting technology, which is widely used in our current lives. exist. Blockchain is a new application model of computer technology such as distributed data storage, point-to-point transmission, consensus mechanism, and encryption algorithm.

Blockchain is an important concept of Bitcoin. It is essentially a decentralized database. At the same time, as the underlying technology of Bitcoin, it is a series of related cryptographic methods. Each data block contains a batch of Bitcoin network transaction information, which is used to verify the validity and anti-counterfeiting of the information and generate the next block.

In a narrow sense, blockchain is a chained data structure that combines data blocks in a sequential manner in chronological order, and is cryptographically guaranteed to be non-tamperable and non-tamperable. Fake distributed ledger.

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

The popular understanding of blockchain technology is: connecting the front, back, left and right blocks of "things" into a chain using one technology, but each block The original data of the block cannot be tampered with. It is a "linked module" technology in the field of Internet of Things that allows participants to trust. The application of blockchain technology is inseparable from the Internet and the Internet of Things. It is based on the integration and interaction of the two, but allows participants to remain independent, decentralized, and work together. With this set of value chain co-construction and sharing, technology.

Characteristics of blockchain: decentralization, openness, autonomy, information cannot be tampered with, and anonymity.

Blockchain is a network that can deliver value. The demand for a network that can deliver value is an important reason for the emergence of blockchain technology. Blockchain emerged driven by the need to protect information with ownership or other value. Through public and private key cryptography, distributed storage and other technical means, blockchain ensures on the one hand the efficient transmission of valuable information, and on the other hand ensures that this information will not be easily copied and tampered with during the transmission process.

Understand the connotation of blockchain from the inevitability of its birth. Blockchain is a distributed accounting technology that solves the shortcomings of centralized accounting and solves the problem of distributed consistency. It is also The connected Internet is upgraded to a value network that ensures the safe and efficient transmission of valuable information.

Blockchain Technology Concept 3

Blockchain: Blockchain is like a globally unique account book.In other words, it is a database that records all transaction history in the network.

Ethereum Virtual Machine (EVM): It allows you to write more powerful programs on Ethereum and script programs on Bitcoin. It is also sometimes used to refer to the Ethereum blockchain, which is responsible for executing smart contracts and everything.

Node: You can run a node to read and write to the Ethereum blockchain, that is, using the Ethereum Virtual Machine. Full nodes require downloading the entire blockchain. Light nodes are still under development.

Miner: Mining, that is, the node that processes blocks on the blockchain. You can see some of the currently active Ethereum miners on this page: stats.ethdev.com.

Proof of Work: Miners are always competing to solve some mathematical problem. The first one to solve the problem (calculate the next block) will be rewarded with Ether coins. All nodes then update their own blockchain. All miners who want to figure out the next block have an incentive to stay in sync with other nodes and maintain the same blockchain, so the entire network can always reach consensus. (Note: Ethereum is planning to move to a proof-of-stake system (POS) without miners, but that is outside the scope of this article.)

Ethereum: Abbreviation ETH. A true digital currency that you can buy and use. Here is a chart from one of the exchanges where Ethereum can be traded. At the time of writing, 1 Ether is worth 65 cents.

Gas: Executing programs and saving data on Ethereum consumes a certain amount of Ethereum. Gas is converted from Ethereum. This mechanism is used to ensure efficiency.

DApp: The Ethereum community calls applications based on smart contracts decentralized applications (Decentralized App). The goal of DApp is (or should be) to have a friendly interface for your smart contracts, plus some extras, such as IPFS, a decentralized network that can store and read data, not from the Ethereum team but in a similar spirit ). DApp can run on a centralized server that can interact with Ethereum nodes, or it can run on any Ethereum equal node. (Take a minute to think about this: Unlike ordinary websites, DApps cannot run on ordinary servers. They need to submit transactions to the blockchain and read important data from the blockchain rather than a centralized database. Compared to typical users When logging into the system, the user may be represented as a wallet address and other user data is stored locally. Many things will be structured differently from current web applications.)

Ethereum client, smart contract language

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Writing and deploying smart contracts does not require you to run an Ethereum node. Browser-based IDEs and APIs are listed below. But if it is for learning, you should still run an Ethereum node to understand the basic components, and running a node is not difficult.

Clients available for running Ethereum nodes

Ethereum has many client implementations in different languages, that is, multiple methods of interacting with the Ethereum network, , including C++, Go, Python, Java, Haskell, etc. Why do we need so many implementations? Different implementations can meet different needs. For example, the goal of Haskell implementation is to be mathematically verifiable, to make Ethereum more secure, and to enrich the entire ecosystem.

At the time of writing this article, I am using the client geth (go-ethereum) implemented in the Go language. At other times, I also use a tool called testrpc, which uses the Python client pyethereum. Later examples will use these tools.

About mining: Mining is fun, a bit like caring for your houseplant, but also a way to learn about the entire system. Although the current price of Ethereum may not even cover the electricity bill, who knows in the future. People are creating many cool DApps that may make Ethereum more and more popular.

Interactive console: Once the client is running, you can synchronize the blockchain, create a wallet, and send and receive Ethereum. One way to use geth is through the Javascript console. In addition, you can use cURL-like commands to interact with the client through JSON RPC. The goal of this article is to take you through the process of DApp development, so I won’t go into details about this. But we should remember that these command line tools are useful for debugging, configuring nodes, and using wallets.

Running the node on the test network: If you run the geth client on the official network, it will take quite a while to download the entire blockchain and synchronize with the network. You can determine if synchronization has occurred by comparing the last block number printed in the node logs with the latest block listed on stats.ethdev.com. ) Another problem is that running smart contracts on the official network requires real Ethereum. Running the node on the test network does not have this problem. At this time, there is no need to synchronize the entire blockchain. Just create your own private chain, which saves time for development.

Testrpc: Use geth to create a test network. Another faster way to create a test network is to use testrpc. Testrpc can help you create a bunch of test accounts with funds at startup. It also runs faster and is therefore better suited for development and testing. You can start with testrpc, and then as the contract slowly takes shape, move to the test network created by geth - the startup method is very simple, you only need to specify a networkid: geth --networkid "12345". Here is the code repository of testrpc, we will talk about it belowSpeaking of it.

Next, let’s talk about the available programming languages, and then we can start the real programming. Solidity is the programming language used to write smart contracts.

There are several languages ​​to choose from when writing smart contracts: Solidity, which is somewhat similar to Javascript, has a file extension of .sol. Serpent, which is similar to Python, has a file name ending in .se. There is also a Lisp-like LLL. Serpent has been popular for a while, but now the most popular and stable one is Solidity, so just use Solidity. I heard you like Python? Use Solidity.

solc compiler: After writing the smart contract with Solidity, you need to use solc to compile it. It is a component from a C++ client implementation. Again, different implementations complement each other. Here is how to install it. If you don't want to install solc, you can also use a browser-based compiler, such as Solidity real-time compiler or Cosmo. The programming sections below will assume you have solc installed.

web3.js API. After the Solidity contract is compiled and sent to the network, you can use Ethereum's web3.js JavaScript API to call it and build web applications that can interact with it.