Liande De "100 Questions on Blockchain" is released: an encyclopedia-like block chain literacy reader (Part 1) _ China

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Topic:What are the new rules for stock transfers

Looking back at history, before that, every industrial revolution was almost a process of social tearing, and even a process of redistribution of social class and wealth.

But the blockchain world has just begun to sprout, and the current situation is endless. While in full swing, while at the same time confused and hesitating; while passionate, while wilting cutting, scams continue. Perhaps the biggest problem of the entire market's doubts is not what the blockchain will become in the future, but what the blockchain is, what it can do, and how it can be related to me. So in the last month, we visited many blockchain carers in China, the United States, Europe, Japan, and South Korea, screened more than 100 blockchain issues that everyone cares about most, and interviewed many professionals through Q&A. Sort out the way.

Our stupid effort was finally jointly produced by Titanium Media and Linked and formed this special issue "100 Questions on Blockchain-A Comprehensive Understanding of Blockchain" to help everyone clearly explain the area of ​​understanding. Block chain, analyze the block chain, hope this special issue booklet can also become your important assistant "red book" for learning the block chain.

* Tips: Since the beginning of 2018, Titanium Media has split the blockchain content and data-related businesses based on its judgment on the blockchain trend and determination to invest in gravity, and established Lende Technology With ChainDD USA, in the past two years, ChainDD has achieved rapid development, and at the same time, it has also become more and more aware of the great value of this field and the coexistence of chaos. We would rather give up many opportunities for speculation and do a lot of such original stupid Kungfu, I hope this kind of dumb kungfu can benefit more people. If you have any ideas for further exchanges, you are also welcome to attend the CHAINSIGHTS Fintech and Blockchain China Summit to be held on December 8, 2019 with the participation of Linktech, which is also an important part of the 2019 T-EDGE Global Innovation Conference , Many domestic and foreign financial policy leaders, traditional financial institutions, emerging blockchain giants and other leaders from all walks of life will gather.

* Tips: Since the beginning of 2018, Titanium Media has split the blockchain content and data-related businesses based on its judgment on the blockchain trend and determination to invest in gravity, and established Lende Technology With ChainDD USA, in the past two years, ChainDD has achieved rapid development, and at the same time, it has also become more and more aware of the great value of this field and the coexistence of chaos. We would rather give up many opportunities for speculation and do a lot of such original stupid Kungfu, I hope this kind of dumb kungfu can benefit more people. If you have any ideas for further exchanges, you are also welcome to attend the CHAINSIGHTS Fintech and Blockchain China Summit to be held on December 8, 2019 with the participation of Linktech, which is also an important part of the 2019 T-EDGE Global Innovation Conference , Many domestic and foreign financial policy leaders, traditional financial institutions, emerging blockchain giants and other leaders from all walks of life will gather.

1. What is a blockchain?

2. What are the characteristics of blockchain?

3. What is Bitcoin and what is the relationship with the blockchain?

4. Who is Satoshi Nakamoto?

5. What does the decentralization of the blockchain mean and how safe is it?

6. What is point-to-point transmission?

7. What is a blockchain node?

8. What is the block height?

9. What is a smart contract?

10. What is a consensus mechanism?

11. What is Segregated Witness?

12. What is digital currency?

13. What is a token?

14. What is mining?

15. What is a mining machine?

16. What is computing power?

17. What are mining pools and mines?

18. What is a wallet, wallet address, private key, and public key?

19. What is the expansion of the blockchain?

Two. Technical Development

20. What mainstream blockchain technologies are there now?

21. What structure does the blockchain consist of?

22. Where does the data exist? Does each node have to have a large enough storage medium?

23. How is cryptography applied in the blockchain?

24. What does distributed data storage in the blockchain mean?

25. How does the distributed storage of the blockchain ensure security?

26. There are roughly several types of consensus mechanisms. What are the differences?

27. Is there a performance bottleneck in the blockchain?

28. How does blockchain achieve data sharing?

29. Why can the blockchain be tamper-proof?

30. How to establish trust between different nodes in the blockchain system?

31. Why does the blockchain fork?

32. What is blockchain cypherpunk?

33. Blockchain efficiency improvement?

34. How many transactions can there be on a block?

35. Why can Bitcoin transactions be proven after confirming more than 6 blocks?

36. Are the blockchains independent after forking?

37. How to calculate the difficulty of proof of work?

38. How to build a public chain?

39. What concepts must be known about the public chain?

40. How to realize decentralization and distributed ledger?

41. Can quantum computers destroy Bitcoin?

42. Does the code of the blockchain project need to be open source? why?

3. Digital Assets Chapter

43. What is the relationship between encrypted digital currency and blockchain?

44. Is the currency market the same as the stock market?

45. What is the central bank's digital currency? Can ordinary people use it? How to get it?

46. What are the active digital currency exchanges in China and who are the main operating entities?

47. Will digital currency replace the current physical currency in the future?

48. What impact will digital currency have on the existing financial system?

49. Ordinary people buy cryptocurrency, do they need real-name authentication in the future?

50. Can ordinary people participate in mining and how to mine?

51. Do all currencies need to be produced by mining?

52. What is the nature of the value of digital currency?

53. How do I personally want to send a coin of my own?

54. What should I pay attention to when mining?

55. Do the coins produced by mining have transaction value?

56. What kind of encrypted wallet is the safest? What kind of wallet is the most convenient?

57. How to store and trade Bitcoin?

58. Do transactions on the blockchain require a fee? How is it determined? Who decides how much?

59. How does a Bitcoin transaction count as a successful transaction?

60. What kind of digital currency is Libra launched by Facebook? Is it related to the blockchain?

61. What are ICO, STO, IEO?

62. What is the relationship between the dark web, cryptocurrency and blockchain?

63. How to distinguish between public chain, private chain, and alliance chain?

Fourth, application landing chapter

64. What is the development process of blockchain applications?

65. What are the current factors restricting the development of blockchain?

66. What is the current status of China's blockchain?

67. What are the applications and successful examples of blockchain applications?

68. What are the active mining machine manufacturers in China, and what are their technology and business conditions?

69. How many well-known public chains are there currently?

70. What industry is suitable for blockchain?

71. What role does blockchain play in "decentralized finance"?

72. What is chain change? How do companies transform the chain through the token economy?

73. What are the "blockchain concept stocks"?

74. How do startups find direction and positioning in the blockchain industry? Is this a game between major manufacturers?

75. Application scenarios of blockchain products

76. How about the talent market in the blockchain industry? (Average salary, user demand)

77. Comparison of the scale of the blockchain market across the country

78. The latest views of investment institutions on the blockchain

79 .What changes can the blockchain bring to society?

80. What is the general situation and future development of the current blockchain market environment?

81. Why should the country re-push blockchain technology?

82. What jargons are there in the blockchain? What do all those "jargons" mean?

83. What is the effect or influence of the blockchain on the actual life of ordinary people?

84. Is it possible to use digital currencies such as Bitcoin to buy goods in daily life?

V. Policies

85. In the context of the domestic development of blockchain, will the government's attitude towards the digital currency market change?

86. In the future, can enterprises independently issue coins for financing?

87. What is the current global attitude towards blockchain and digital currency?

88. What is the current global view of Libra?

89. What are the current countries' views on central bank digital currencies?

90. At present, what blockchain-related policies have been issued by various local governments in China?

91. I heard that Hong Kong has begun to issue virtual bank licenses. How many companies have obtained licenses?

92. How will China advance the development of the blockchain industry in the future?

93. What does China need to do to develop the blockchain in an orderly manner?

94. What are the requirements of relevant management departments for China's vigorous development of blockchain?

VI. Risks

95. What are the disadvantages of blockchain?

96. Is there a risk of theft of digital currency?

97. If an encrypted exchange is stolen, how can users recover their losses by law?

98. How to simply distinguish whether a blockchain project is a scam (air coin)?

99. How to identify whether a blockchain project is an MLM currency?

100. If I typed the cryptocurrency into the wrong address, or was cheated and stolen, can I get it back? What legal channels are there to protect my legal rights?

Part I (Chapters 1-3) 1. Core Concepts

1. What is a blockchain?

Blockchain is a data transmission method that integrates cryptography, distributed storage, smart contracts, consensus algorithms and other emerging technologies. It is essentially an integrated technology rather than The invention of a specific technology.

Blockchain is essentially a distributed database system that applies cryptography technology, multi-party participation, joint maintenance, continuous growth and non-tamperable, also known as distributed shared ledger. In the process of data upload, the data will be packed together to form a data block, and the packaged data block has another scientific name called a block, and each block is connected in chronological order to form a data block. The chain network, because the entire network structure is composed of blocks and chains, so it is named Blockchain. As a shared ledger, it can be understood that each ledger page is a block, each block is filled with transaction records, and the blocks are connected and closely connected to form a chain structure.

Therefore, the blockchain uses oneThis decentralized way solves the problems of trust endorsement and value transmission.

2. What are the characteristics of blockchain?

The characteristics of the blockchain: anonymity, scalability, openness, irrevocability, non-tampering, and encryption security.

Blockchain is a transparently shared general ledger. This ledger is open to the entire network. When you get its public key, you will know how much money is in the account, so any time Value conversion, interested people from all over the world can watch you by the side, conversion is confirmed by miners for you, so it is an Internet consensus mechanism. There is no way to tamper with this ledger, because your behavior is not recorded by you, not by you, but by other people on this network to determine whether this is the case.

3. What is Bitcoin and what is the relationship with the blockchain?

On November 1, 2008, a person named Satoshi Nakamoto published a paper entitled "Bitcoin: A Peer-to-Peer Electronic Cash System" on the Internet. This is the first time Bitcoin has appeared in people's eyes. The Bitcoin algorithm client was launched on January 3, 2009, and this special financial system was officially launched. This day was also the first "Genesis Block" of Bitcoin to appear. The first block reward is 50 bitcoins. 10 minutes after the genesis block is released, the first 50 bitcoins are generated, and the total amount of money at this time is 50. Then Bitcoin increased at a rate of about 50 every 10 minutes. Therefore, January 3, 2009 has always been defined as the birth date of Bitcoin.

According to Satoshi Nakamoto’s Bitcoin white paper algorithm, the total amount of Bitcoin issuance is limited to 21 million. When the total amount reaches 10.5 million (50% of 21 million), the block reward is halved to 25 A. When the total amount reaches 15.75 million (5.25 million new output, which is 50% of 1050), the block reward is halved to 12.5. The currency system used to have no more than 10.5 million in 4 years, and the total number after that will be permanently limited to approximately 21 million.

With the automatic and good operation of Bitcoin since 2009, more and more users around the world have begun to hold Bitcoin and trade Bitcoin. This set of technical underlying systems that support Bitcoin operation has also begun to be affected. The attention of the technical community. Later generations began to study the formation mechanism and link mechanism of the block, and found that the underlying block system of Bitcoin is essentially a decentralized database. At the same time, as the underlying technology of Bitcoin, it is a series of data related to the use of cryptographic methods. Block, each data block contains a batch of Bitcoin network transaction information, used to verify the validity of the information (anti-counterfeiting) and generate the next block, and this is named Blockchain. Blockchain, as the underlying technology system of Bitcoin, has become well-known, and more and more people have begun to tap the value of blockchain in other applications. Therefore, some people call Bitcoin the first successful application of blockchain, but in terms of the time when the concept appeared, there was Bitcoin first and then blockchain.

4. Who is Satoshi Nakamoto?

As the inventor of Bitcoin, Satoshi Nakamoto is known as the "Father of Bitcoin". But since 2010, he has gradually faded out and the project has been handed over to other members of the Bitcoin community.

It is worth mentioning that Satoshi Nakamoto is a very low-key person. His identity is still a mystery to this day, but the Bitcoin account under his name has not been moved yet, and it is still Bitcoin Global The largest currency holding account. Although people have made many speculations about his identity, and some people have jumped out to say that he is Satoshi Nakamoto, the credibility of these claims is really too low.

* Chainde has invited and had a conversation with Martii Malmi, the first core developer of the Satoshi Nakamoto Bitcoin project, and talked about Satoshi Nakamoto and the early Bitcoin development process, interested You can move to the chain to view the detailed text:

"[Chain Dede Global Travel·Beijing] Looking for Satoshi Nakamoto: The Blockchain Future in the Post-Bitcoin Era"

5. What does the decentralization of the blockchain mean and how secure is it?

Decentralization, for example, like Taobao, which is usually used for shopping on Taobao, it is actually centralized. Whether it is choosing goods or payment transactions, it is both for buyers and sellers. A platform that cannot be bypassed is Alibaba. As a central platform, it maintains the entire online shopping ecosystem. The so-called decentralization is to remove the center of Alibaba and re-establish a new set of data that everyone can manage together and can trade freely. On the regulatory side, centralization hasThere are many problems. In the central language model, data is stored in the central server. Once this server is down, the entire network will have problems. In addition, industry data is concentrated in a few giant companies. Because data management is not transparent, once The consequences of data leakage are catastrophic.

The benefit of decentralization lies in the fact that everyone participates in data maintenance, and data information is no longer centralized, thus solving these problems. Therefore, decentralization can be said to be an uninnovated change in the Internet world. Everyone Can participate equally in the management and maintenance of data. Blockchain is hailed as a trend because of the fairness of decentralization.

Blockchain is a distributed database technology. Distributed technology mainly refers to storage architecture. The distributed architecture adopted by the blockchain not only stores the ledger data on each node, but each node must contain the data of the entire ledger. This completely distributed architecture brings higher security than centralized, and no one can destroy all nodes at the same time.

6. What is point-to-point transmission?

Peer-to-peer (P2P) is also called peer-to-peer interconnection network technology. There is no central node in the network, and the rights of each node are the same. Transactions can be performed between two points. After the transaction is successful, all nodes in the entire network will record the transaction. The advantage of this model is that it does not gather dependencies on a few servers, thus avoiding a single point of failure.

7. What is a blockchain node?

The terminal responsible for maintaining the operation of the network can be called a node. In the Internet field, all data operations of an enterprise are concentrated in its own server, so this server is a node. For example, the WeChat we use handles so many chat messages and transfers every day. The storage and operation of these data are in Tencent's server. Then this server that processes data can be called a "node"

Blockchain is a decentralized distributed database. It does not rely on which centralized server, but by Qianqian Composed of tens of thousands of "small servers". As long as we download a blockchain client, we become one of the thousands of "small servers".

Nodes are divided into "full nodes" and "light nodes". A full node is a node that has all the transaction data of the entire network, and a light node is a node that only has transaction data related to itself. The more and more nodes are distributed, the more decentralized the blockchain network, and the safer and more stable the network operation.

8. What is the block height?

The Bitcoin network produces a block that records transactions approximately every 10 minutes. From the initial 1 block and 2 blocks, it slowly accumulates to nearly 500,000 blocks now. The height of the Bitcoin block refers to how many blocks are generated. For example, BCX forks at height 498888, which means that Bitcoin executes the fork operation when the 498888th block is generated.

9. What is a smart contract?

Smart Contract (Smart Contract) is not a new concept. As early as 1995, it was proposed by cross-field legal scholar Nick Szabo: Smart Contract is a set of commitments defined in digital form ( Promises), including agreements on which contract participants can execute these promises. In the blockchain field, the essence of a smart contract can be said to be a piece of code running in the blockchain network. It implements the automatic processing of traditional contracts in the form of computer instructions and completes the business logic assigned by the user.

10. What is a consensus mechanism?

The consensus mechanism is how to reach a consensus between all bookkeeping nodes to determine the validity of a record. This is not only a means of identification, but also 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 completely refer to the number of nodes, but also the computing power and the number of shares. Or other features that can be compared by computers. "Everyone is equal" means that when nodes meet the conditions, all nodes have the right to give priority to the consensus result, and it may be the final consensus result after being directly recognized by other nodes.

* For more information about the consensus mechanism, please refer to the article on Link Dede

"【Get to the vernacular] On the way to the final upgrade of Ethereum, why change the consensus mechanism? 》

11. What is Segregated Witness?

Usually abbreviated as SegWit, it is a way to expand the blockchain.

At present, each block on the blockchain not only records the specific information of each transfer transaction, that is, how many bitcoins the account receives or transfers at which point in time, but also contains the details of each transaction. Digital signatures, and digital signatures account for a relatively large proportion. When packing blocks, miners need to use digital signatures to verify each transaction one by one, and then record the transaction in the block after confirming that there is no problem. Segregated witness is to take out the digital signature information in the block, so that each block can carry more transactions, so as to achieve the purpose of expansion. ”

12. What is digital currency?

Digital currency is also called encrypted currency, which is a kind of virtual currency based on node network and digital encryption algorithm. Currency.

Not issued by the central bank or the authorities, nor linked to legal tender, but because it is accepted by the public, it can be used as a means of payment, and can also be transferred, stored or traded in electronic form.

13. What is a token?

It can be seen in the blockchain field Work is a circulated encrypted digital equity certificate.

(1) Equity certificate (a kind of equity certificate in digital form, representing a kind of right, an inherent intrinsic value and use value);

(2) Encryption (in order to prevent tampering, protect privacy, etc.);

(3) Circulation (transaction, exchange, etc.).

14. What is mining?

Mining is to use a chip to perform a calculation related to a random number, and then exchange the corresponding digital currency as a reward after the answer is obtained.

Previously, mining used computers to perform related calculations to obtain digital currency rewards. However, with the continuous increase of computing power, the cost of using computers to mine is getting higher and higher. Later, there has been a special acquisition of digital currency. This kind of machine is also called a mining machine.

15. What is a mining machine?

Used to mine (produce) cryptocurrency Machine.

Broadly speaking, a mining machine can be any machine that can run mining programs, such as professional mining machines, home computers, smart phones, servers, smart routers, smart watches, smart TVs, etc. .

In a narrow sense, mining machines refer to professional mining equipment, such as ASIC mining machines, graphics card mining machines, and exclusive mining machines (PFS mining machines) for some currencies.

16. What is computing power?

Computing power (also known as hash rate) is a unit of measurement for the processing power of the Bitcoin network. It is a computer (CPU) calculation The output speed of the hash function.

In the process of obtaining bitcoin through "mining", we need to find the corresponding solution m, and for any 64-bit hash value, we need There is no fixed algorithm to find its solution m. It can only rely on the random hash collision of the computer. How many hash collisions a mining machine can make per second is the representative of its "computing power". The unit is written as hash/s. It is the so-called proof of work mechanism POW (Proof Of Work).

17. What are mining pools and mines?

After the computing power of the entire network has increased to a certain level, the probability of a single machine digging a block becomes very low. The development of this phenomenon has prompted some geeks on "bitcointalk" to develop a method that can combine a small amount of computing power to operate jointly. The website built in this way is called a "mining pool" (MiningPool).

The income distribution of the mining pool mainly includes three forms: PPLNS, PPS, and PROP.

The so-called Bitcoin mining farm is to build a factory where dozens or thousands of mining machines are put together to perform mathematical operations and mine Bitcoin. This involves power consumption issues. The cost of a mine includes: construction cost, equipment cost, maintenance cost, network cost, and other costs.

* About mining, computing power, mining machines, mining farms, etc., Chaindede has published a series of articles for science popularization and discussion. For details, please download Chaindede App to see more articles:

18. What is a wallet, wallet address, private key, and public key?

Encrypted digital currency wallets can provide basic financial functions such as the creation of wallet addresses, encrypted digital currency transfers, and querying the transaction history of each wallet address.

Wallets are generally divided into cold wallets and hot wallets. The main difference is whether the secret key can be accessed on the Internet.

Each wallet address corresponds to a public key and a private key. The private key can only be owned by the user, while the public key can be publicly issued and distributed, and can be obtained as long as there is a request.

Example: A sender needs to send a message to a recipient, and the confidentiality of the information is necessary. The sender uses the recipient’s public key to encrypt, but only the recipient’s private The key can decrypt this information.

Blockchain finance is a branch of technology finance. The application of blockchain technology can solve the trust and security issues in transactions. Through the blockchain, both parties to a transaction can carry out economic activities without the need for a third-party credit intermediary, thereby reducing the cost of assets that can be transferred globally.

19. What is the expansion of the blockchain?

In order to ensure the security and stability of Bitcoin, Satoshi Nakamoto limited the block size to 1MB. However, as the number of transactions on the blockchain continues to increase, the processing speed of 7 transactions per second has clearly been unable to meet user needs. Therefore, by modifying the underlying code of Bitcoin, the purpose of improving transaction processing capabilities is achieved.

At present, there are two technical solutions for Bitcoin expansion: 1. Increase the block capacity by changing the content of the consensus part of the block chain. 2. Move a large number of calculations to the chain, that is, solve the problem through the side chain technology.

*To learn more about the expansion of the blockchain, you can also download the LinkDeck App to see more articles

Two, technical development articles

20. What mainstream blockchain technologies are there now?

Bitcoin is the earliest true decentralized blockchain technology.

Ethereum is equipped with a powerful Turing-complete smart contract virtual machine, so it can become the parent platform for all blockchain projects.

The IBM HyperLedger fabric is an excellent implementation of the alliance chain.

Ripple, the world's first open payment network, is a point-to-point global payment network based on block connections.

21. What structure does the blockchain consist of?

Blockchain is a chain storage structure formed by interconnecting blocks. Blocks are the data elements in the chain storage structure. The first block is called the founding area. Piece.

General blocks include two parts: block header and block body. The block header contains the identification information of each block, such as version number, hash value, timestamp, block height and other information; the block body mainly contains specific transaction data.

22. Where does the data exist? Does each node have to have a large enough storage medium?

The blockchain adopts a distributed storage method. The data of the blockchain is used and stored by the blockchain nodes, and multiple nodes are linked through the network to form a complete Blockchain network.

Regarding the size of the node, take the Bitcoin network node as an example. There are full nodes, pruning nodes, and SPV lightweight nodes. This classification method Based on two differences: one is whether the node has downloaded the latest and most complete Bitcoin blockchain; the other is whether the node can independently verify bitcoin transfer transactions, that is, whether it can independently realize the basic functions of a node.

The complete node downloaded the latest complete blockchain data, which is the backbone of the Bitcoin network. There are mainly two types of people who use this type of node, one is the independent mining miner, and the other is the user who runs the Bitcoin core software with default settings.

The pruning node can also complete the confirmation of Bitcoin transfer independently, but it does not download the entire blockchain to the local.

Lightweight nodes are generally used on mobile computing devices. Due to capacity limitations and high requirements for portability, people usually do not download blockchains locally. Therefore, the wallet operator will pass SPV (Simplepayment verification) agreement, which checks and confirms the transfer in each user's wallet with the complete blockchain on the Internet.

In the Ethereum network, there are similar full nodes, light nodes, and archive nodes. Therefore, not every node needs a huge storage space. It should be selected according to the function of the node.

23. How is cryptography applied in the blockchain?

In blockchain technology, cryptography mechanisms are mainly used to ensure the integrity, authenticity and privacy of transaction information.

Cryptography in the blockchain includes Bloom filters, hash functions, encryption and decryption algorithms, digital certificates and digital signatures, homomorphic encryption, PKI systems, etc.

*To learn more about blockchain privacy and cryptography, you can download the Linked App to see more articles

24. Distributed data in blockchain What does storage mean?

The essence of the blockchain is a decentralized database. The data sharing of blockchain technology is a distributed accounting book, which is essentially a series connected in chronological order. In the chain, all transactions starting from the genesis block are recorded in the block. Account information such as transaction records will be packaged into blocks and encrypted, and time stamped at the same time. All blocks are connected in the order of the timestamp to form a general ledger. The blockchain consists of multiple independent nodes with the same status to store complete data according to a blockchain structure, and the consistency of storage is ensured through a consensus mechanism. Once the data is recorded, the data in a block will be irreversible.

25. How does the distributed storage of the blockchain ensure security?

Due to the blockchain structure, the blocks are strung together into a chain. If you want to tamper with data, it is useless to tamper with only one node. You need to tamper with the entire chain at the same time. The node can truly tamper with the data. This kind of tampering is extremely difficult and almost impossible to complete. Blockchain Through data encryption and authorization technology, the information stored on the blockchain is public, but the account identity information is encrypted and can only be accessed with the authorization of the data owner to ensure data security and personal privacy.

26. There are roughly several types of consensus mechanisms. What are the differences?

There are nine more common types:

(1) Proof of work-more work, more money

In the PoW mechanism, according to the work of miners The amount to perform the distribution of currency and the determination of accounting rights. The winner of the computing power competition will receive the corresponding block accounting rights and bitcoin rewards. Therefore, the higher the computing power of the mining machine chip, the longer the mining time, and the more digital currency can be obtained.

Advantages: The algorithm is simple and easy to implement; nodes can reach a consensus without exchanging additional information; destroying the system requires huge costs.

Disadvantages: waste of energy; block confirmation time is difficult to shorten; the new blockchain must find a different hash algorithm, otherwise it will face Bitcoin's computing power attack; prone to bifurcation , Need to wait for multiple confirmations; there is never finality, and a checkpoint mechanism is needed to make up for finality.

At present, there are many digital currencies based on the PoW consensus mechanism. Most of the early digital currencies such as Bitcoin, Litecoin, Dogecoin, Dash, and Monero are all PoW consensus mechanisms.

(2) PoS (Proof of Stake) proof-of-stake algorithm-the more you hold, the more you get

The POS mechanism uses a mechanism similar to proof-of-stake and voting to select Account person, it creates the block. The more equity you hold, the greater the privileges, and the more responsibilities you need to bear to generate blocks, and at the same time the power to gain more income. In the POS mechanism, the currency age is generally used to calculate the accounting rights. Each currency held for one day is counted as a currency age. For example, if you hold 100 coins for a total of 30 days, then the currency age at this time is 3000. Under the POS mechanism, if the bookkeeper finds a POS block, his coin age will be emptied to 0. For every 365 coin age emptied, he will receive 0.05 coin interest from the block (which can be understood as annual Interest rate 5%).

Advantages: To a certain extent, the time for reaching a consensus is shortened; it is no longer necessary to consume a lot of energy for mining.

Disadvantages: mining is still needed, which essentially does not solve the pain points of commercial applications; all confirmations are only a probabilistic expression, not a deterministic thing. In theory, there may be other attacks. .

Be the first to use equityThe blockchain project that proves the consensus mechanism is PeerCoin, which was born in 2012. The first three phases of Ethereum adopt the PoW consensus mechanism. In the fourth phase, Ethereum will adopt the proof-of-stake mechanism. In addition, both Quantum Chain and Blackcoin adopt the POS consensus mechanism. .

(3) DPOS (Delegated Proof-of-Stake) stock authorization certificate

The main difference between the share authorization certificate (abbreviation: DPoS) and PoS is that the node elects several agents, It is verified and booked by an agent, but its supervision, performance, resource consumption and fault tolerance are similar to those of POS. The popular understanding is similar to board voting. Coin holders vote for a certain number of nodes, and the nodes perform proxy verification and accounting.

The entire voting model is: Become a representative ---- Authorize voting ---- Keep the representative honest ---- Resist attacks

Advantages: Significantly reduce participation in verification and accounting The number of nodes can reach consensus verification in seconds.

Disadvantages: The consensus mechanism still needs tokens and many businesses do not need tokens.

(4) PBFT (Practical Byzantine Fault Tolerance) Practical Byzantine Fault Tolerance-Distributed Consensus Algorithm

Practical Byzantine Fault Tolerance is the premise of ensuring liveness & safety The following provides (n-1)/3 fault tolerance. In distributed computing, different computers try to reach a consensus through message exchange; but sometimes, the coordinator computer (Coordinator / Commander) or member computer (Member /Lieutanent) on the system may exchange wrong messages due to system errors. Affect the final system consistency. The Byzantine Generals problem is based on the number of wrong computers to find possible solutions. This cannot find an absolute answer, but it can only be used to verify the effectiveness of a mechanism.

The possible solution to the Byzantine problem is: consistency is possible when N ≥ 3F+1. Among them, N is the total number of computers, and F is the total number of problematic computers. After the information is exchanged between the computers, each computer lists all the information obtained, and most of the results are used as a solution. Advantages: The operation of the system can be separated from the existence of the currency. Each node of the pbft algorithm consensus is composed of business participants or regulators, and the security and stability are guaranteed by the business related parties; the consensus delay is about 2~5 seconds, which is basically achieved Commercial real-time processing requirements; high consensus efficiency, which can meet the needs of high-frequency trading volume. Disadvantages: When 1/3 or more of the bookkeepers stop working, the system will not be able to provide services; when 1/3 or more of the bookkeepers cooperate with each other, and all other bookkeepers are exactly divided into two isolated network islands At this time, malicious bookkeepers can cause the system to fork, but will leave cryptographic evidence; the degree of decentralization is not as good as the consensus mechanism on the public chain; and it is more suitable for a multi-center business model with multi-party participation.

To put it more popularly, it is to adopt the consensus mechanism of "the minority obeys the majority" to elect leaders and keep accounts. This mechanism allows Byzantine fault tolerance, allows strong supervisory nodes to participate, has the ability to classify permissions, has high performance, and consumes The performance is low, and each round of bookkeeping will be jointly elected by the entire network nodes to allow 33% of the nodes to do evil, and the fault tolerance is 33%.

(5) dBFT (delegated BFT) authorized Byzantine fault tolerance algorithm

Improved on the basis of practical Byzantine fault tolerance:

The C/S (client/server ) The request response mode of the architecture is improved to a peer-to-peer node mode suitable for P2P networks; the static consensus participating nodes are improved into consensus participating nodes that can dynamically enter and exit; a set of consensus-based participating nodes is designed based on the proportion of equity held The voting mechanism of, through voting to determine the consensus participating nodes (bookkeeping nodes); the introduction of digital certificates in the blockchain solves the problem of authenticating the real identity of the bookkeeping nodes in voting.

Advantages: professional bookkeeper; can tolerate errors; bookkeeping is completed by multiple people; each block has finality and will not fork; the reliability of the algorithm has strict mathematical proofs.

Disadvantages: When 1/3 or more of the bookkeepers stop working, the system will not be able to provide services; when 1/3 or more of the bookkeepers cooperate with each other, and all other bookkeepers are When the two networks are split, a malicious bookkeeper can cause the system to fork.

In short, the core point of the authorized Byzantine fault-tolerant mechanism is to ensure the finality of the system to the greatest extent, so that the blockchain can be applied to real goldFusion application scenarios.

(6) DAG (Directed acyclic graph)-no concept of blockchain

DAG first appeared to solve the efficiency problem of blockchain. It changes the chain storage structure of the block and stores the block through the topology of the DAG. When the block packing time is unchanged, N blocks can be packed in parallel in the network, and the transactions in the network can accommodate N times. Later, DAG developed into a break away from the blockchain, and proposed the concept of blockless. When a new transaction is initiated, it is only necessary to select a relatively new transaction that already exists in the network as the link confirmation. This approach solves the problem of network width and greatly accelerates the transaction speed.

Advantages: fast transaction speed; no mining required; extremely low handling fee.

Disadvantages: The size of the network is small, which makes it easy to become centralized; the security is lower than the PoW mechanism.

(7) Pool verification pool-private chain dedicated

Pool verification pool, based on traditional distributed consistency technology, plus a data verification mechanism; it used to be a major industry chain The scope of the consensus mechanism is in use, but with the gradual decrease of private chain projects, it gradually begins to lose momentum.

Advantages: It can work without tokens. On the basis of mature distributed consensus algorithms (Pasox, Raft), it can realize second-level consensus verification.

Disadvantages: The degree of decentralization is not as good as bictoin; it is more suitable for a multi-center business model involving multiple parties.

Custom consensus mechanism and hybrid consensus mechanism-private customization

(8) Ripple-RPCA (Ripple Protocol consensus algorithm)

Ripple consensus mechanism RPCA is a consensus mechanism similar to PBFT, which is a consensus mechanism for node voting. The initial list of special nodes is like a club. To accept a new member, 51% of the club members must vote. Consensus follows the 51% power of this core member, while outsiders have no influence. Since the club started from "centralization", it will always be "centralized", and if it starts to corrupt, shareholders can't do anything. Like Bitcoin and Pidiancoin, the Ripple system separates shareholders from their voting rights and is therefore more centralized than other systems. Stellar's consensus mechanism SCP (Stellar Consensus Protocol) evolved on the basis of the "Ripple consensus algorithm".

(9) Hcash——PoW+PoS consensus mechanism

After Hcash adopts a hybrid consensus mechanism, both Hcash users and miners can participate in the voting and jointly participate in the Hcash community’s Significant decision;

Hcash's PoS also provides a check and balance mechanism for unqualified miners; through PoS+PoW fair distribution of voting weights according to the number of coins and workload, community autonomy can be achieved; through PoW, This makes Hcash have the hard cost of mining as a guarantee of the currency price, and restricts the problem of excessive concentration of digital currency in the separate PoS mechanism; PoS allows small and medium investors to focus on the medium and long-term development of the project, and small and medium investors are more inclined to put the currency Conducting PoS in the wallet instead of on the exchange and ready to trade at any time makes the Hcash ecosystem healthier. People will focus more on Hcash technology and landing applications instead of just focusing on short-term price fluctuations; in terms of security Since PoW must pass PoS verification before it can take effect, PoW miners cannot decide and change network rules on their own, which effectively resists 51% attacks.

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"[Dawenguan Chain] Blockchain Security Aspects: 51% Attacks and Witches Attack"

27. Is there a performance bottleneck in the blockchain?

The performance indicators of the blockchain mainly include transaction throughput and latency. Transaction throughput indicates the number of transactions that can be processed in a fixed time, and delay indicates the response and processing time to the transaction. In practical applications, two factors need to be considered-it is incorrect to only use transaction throughput without considering the delay. Long-term transaction response will hinder the user's use and affect the user experience; only use the delay without considering the delay. Throughput will lead to a large number of transaction queues, some platforms must be able to handle a large number of concurrent users, and technical solutions with too low transaction throughput will be directly abandoned.

Currently, Bitcoin theoreticallyA maximum of seven transactions can be processed per second, and a block is generated every ten minutes, which is equivalent to a transaction throughput of 7 and a transaction delay of 10 minutes. In fact, it takes about 6 blocks to wait for the final confirmation, which means The actual transaction delay is 1 hour. Ethereum has improved slightly, but it is far from meeting application requirements. Therefore, the blockchain technology has a performance bottleneck.

From the perspective of blockchain technology, the current factors affecting blockchain performance mainly include broadcast communication, information encryption and decryption, consensus mechanism, transaction verification mechanism and other links. For example, the goal of the consensus mechanism is to make the information of the participating nodes consistent, but reaching a consensus in a highly decentralized system is itself a time-consuming task. If you consider that there will be nodes doing evil, this will increase the processing complexity.

28. How does blockchain achieve data sharing?

Blockchain technology is not concerned with the sharing of data, but the sharing of data control authority. The authority here mainly refers to the right to modify and increase data. It mainly includes two One meaning: one is who can modify the data; the other is how to modify it.

In the Internet mode, data reading, writing, editing, and deletion are generally accompanied by identity authentication operations. Only a specific person can modify the data. In the blockchain mode, especially Under the public chain system, anyone can participate in the reading and writing of data, and a trustless system is constructed in the form of a distributed ledger. Organizations or individuals involved in reading and writing can distrust each other, but can store data in the system A consensus is reached on the final state.

Simply put, the essential difference between blockchain-based sharing and Internet-based sharing is that the blockchain is not only sharing data, but controlling the data.

Since the website operators completely control the central server, these organizations can edit and process data at will. Although the organization also needs to complete data modification and other activities under certain laws and agreements, it is difficult for individual users to enjoy complete control because it is the party that controls the resources.

To give a simple example, a user uploads a photo to the website platform, and hope that friends can see this photo. Excluding some illegal elements, who is the final control of this photo? Obviously, from the user's point of view, this photo belongs to him, but in fact, these social networking sites are the real controllers. They can modify it at will, but the user has no choice. In other words, under the existing Internet system, as long as you have the right to operate the website platform, you can completely control the data on the platform.

Under the blockchain system, data is not controlled by any authoritative party, and its authority is controlled by rules. The main goal of these rules is to specify what information is valid, and at the same time It also specifies how participants should respond to it.

These rules are usually predefined, and participants who join the blockchain network must abide by the rules. Of course, technically speaking, participants can ignore certain rules and construct invalid data according to their own interests. However, due to the existence of the blockchain consensus mechanism, other participants can exclude these invalid data from the network according to predefined rules.

In general, the blockchain regulates the writing behavior of data according to the technical rule system, and the Internet controls data through power and resources. This is a blockchain-style sharing and an Internet-style The fundamental difference in sharing.

Blockchain is a form of permission sharing, allowing each participant to act as a data provider, verifier, and user at the same time to jointly maintain the security and effectiveness of blockchain data.

29. Why can the blockchain not be tampered with?

Block chains are linked together from scratch in an orderly manner. Each block points to the previous block, which is called a sub-block of the previous block. The block is called the parent block.

Each block has a block header, which contains the hash value generated by the parent block header through the algorithm, and the parent block can be found through this hash value. When there is any change in the parent block, the hash value of the parent block also changes. This will force the hash value field of the sub-block to change, and so on, the subsequent sub-sub-blocks and sub-sub-sub-blocks will be affected. Once a block has many descendants, unless the blocks of all descendants of this block are recalculated, such recalculation requires a huge amount of calculation, so the longer the block chain, the more the block history cannot be changed.

30. How to establish trust between different nodes in the blockchain system?

Node A is connected to the blockchain network for the first time.First, an algorithm will be used to find the closest network node to it.

The node sends a message containing its own IP address to the neighboring node, and the neighboring node distributes and broadcasts the message to the node connected to it, and so on, eventually leading to the new node’s The IP address is distributed across the entire network, and each network node knows the address of node A and can establish a direct connection with it.

The new node establishes more connections, so that the node is received by more nodes in the network, and the connection is more stable.

31. Why does the blockchain fork?

The blockchain fork is actually caused by the upgrade of the blockchain system. Each upgrade may be accompanied by a change in the consensus rules of the blockchain, which will lead to an upgrade of the system in the entire network The nodes of the system and the nodes of the unupgraded system operate under different rules, so a fork occurs. For example, when there is a new version of the App we use, some people have upgraded, and some people have not upgraded, and both versions can be used at the same time.

32. What is blockchain cypherpunk?

Satoshi Nakamoto’s Bitcoin white paper was first published in "Cypherpunk". In a narrow sense, "cypherpunk" is an encrypted e-mail system.

In 1992, Tim May, a senior scientist at Intel, launched a cypherpunk mailing list organization. In 1993, Eric Hughes wrote a book called "Cyberpunk Manifesto". This is also the first time the term "cypherpunk" (cypherpunk) appears. There are about 1,400 users of "cypherpunk", and the topics of discussion include mathematics, encryption technology, computer technology, politics and philosophy, as well as private issues. Early members include many IT elites, such as Assange, the founder of "WikiLeaks", Bram Cohen, the author of BT download, Sir Tim-Berners Lee, inventor of the World Wide Web, Nick Sabo, who proposed the concept of smart contracts, and Facebook’s Sean Parker, one of the founders. Of course, it also includes Satoshi Nakamoto, the inventor of Bitcoin.

According to statistics, before the birth of Bitcoin, cypherpunk members discussed and invented as many as 10 digital currencies and payment systems that failed.

33. Blockchain efficiency improvement?

The address is obtained through a series of transformations of the public key, the main one being multiple hash operations.

Since the irreversible hash operation is used in the conversion process, the public key cannot be calculated backward from the address, so it is still safe.

34. How many transactions can there be on a block?

Take the Bitcoin block as an example, the upper limit of a block size is about 1MB, and the size of each transaction varies. Generally, the average size of a transaction is about 250 bytes. 1M can hold more than 3000 transactions.

35. Why can Bitcoin transactions be proven after confirming more than 6 blocks?

In order to avoid losses caused by double spending, it is generally believed that Bitcoin transactions after 6 blocks are confirmed basically cannot be tampered with. Take an example to explain the double-spending process: Suppose Xiao Hei sends 666 BTC to Da Bai and is packed into the Nth block. Within a few minutes, Xiao Hei repented. With more than 50% of the computing power under his control, he launched a 51% attack. By removing the 666 BTC transaction sent to Da Bai, he reorganized the Nth block and was reorganizing. Continue to extend the block after the Nth block to make it the longest legal chain.

Generally speaking, the more blocks that are confirmed, the more secure, and the lower the possibility of tampering and reorganization after a 51% attack. Therefore, 6 blocks are not hard, but they are 6 blocks, the possibility of being tampered with is low. For large transactions, of course, the more blocks the better, but for small benefits, one block is enough.

36. Are the blockchains independent after forking?

Blockchain forks are divided into two categories: one is a hard fork and the other is a soft fork. The biggest difference between the two is whether they are compatible with the old version of the protocol. Hard forks are completely incompatible, while soft forks are compatible. So after the hard fork, it is independent, but the soft fork is not.

37. How to calculate the difficulty of proof of work?

Difficulty value = maximum target value/target value

Among them, the maximum target value is a constantValue:

0x00000000FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF

The difficulty value is inversely proportional to the target value.

38. How to build a public chain?

To build an Ethereum public chain is actually to run an Ethereum node locally, and then connect to the Ethereum mainnet. Considering that the blocks of the main network will take up a lot of hard disk space, when starting the node, you can specify the directory where the data is stored. Run the command: ./geth --ipcpath gethdir/geth.ipc --datadir gethdir console After the node is successfully started, Enter the console interactive interface, the block information of the main network will be actively synchronized.

39. What concepts must be known about the public chain?

(1) Zero-knowledge proofs

"Zero-knowledge proofs" zero-knowledge proofs, abbreviated as ZKPs, refer to the ability of the prover to provide In the case of any useful information, the verifier believes that a certain assertion is a correct agreement. It looks very complicated, but the way to implement it is very simple: A has to prove to B that he knows the answer to a specific Sudoku, but he cannot tell B the solution of the Sudoku. B can randomly designate a row, column or Jiugongge. A writes down all the numbers in this row, column and Jiugongge in ascending order, which contains all the numbers from 1-9, which can prove that A really knows this number. The answer to the unique question.

In this process, once A knows the row, column or nine-square grid designated by B in advance, he can cheat during the verification process, so B needs a real random number to ensure that this verification method is safe .

In the blockchain, the use of zero-knowledge proof between nodes can make the verifier believe that the block is legal without providing any useful information to the verifier.

(2) Asymmetric encryption algorithm

Asymmetric encryption algorithm is also called public-key cryptography (English: Public-key cryptography, is an algorithm of cryptography, it needs Two keys, one is a public key, the other is a private key; one is used for encryption, the other is used for decryption. The ciphertext obtained after using one of the keys to encrypt the plaintext can only be used with the corresponding Another key can be used to decrypt the original plaintext; even the key used for encryption cannot be used for decryption. Since encryption and decryption require two different keys, it is called asymmetric encryption; it is different from encryption and decryption. Decryption uses symmetric encryption with the same key. Although the two keys are mathematically related, if one of them is known, the other cannot be calculated based on this; therefore, one of them can be disclosed, called the public key, and can be The unpublished key is a private key, which must be kept strictly secret by the user. It will never be provided to anyone through any means, and will not be disclosed to the other trusted party to communicate.

(3) The "Impossible Triangle" of the public chain

means that in the process of public chain design, security, decentralization and high throughput cannot be achieved at the same time. One of them must be Compromise.

(4) Byzantine Generals Problem

The Byzantine Generals Problem (Byzantine Generals Problem) is a distributed issue proposed by Leslie Lampert in his paper of the same name. Peer-to-peer network communication fault tolerance.

In distributed computing, different computers reach a consensus through communication and exchange information and act in accordance with the same set of collaborative strategies. However, sometimes, member computers in the system may make mistakes and send Wrong information, the communication network used to transmit information may also cause information damage, making different members of the network draw different conclusions about the overall cooperation strategy, thereby destroying the consistency of the system. The Byzantine Generals problem is considered to be the most fault-tolerant problem. One of the difficult types of problems.

Specifically, the Byzantine generals problem is a thought experiment, that is, a group of Byzantine generals each lead an army to siege a city together. The action strategy of each army is limited to There are two types of attack or withdrawal. Because some troops attack and some troops leave may cause catastrophic consequences, so generals must vote to reach a consensus strategy, that is, all troops attack together or all troops leave together. Because the generals are located in different directions in the city , They can only communicate with each other through messengers. During the voting process, every generalInform all other generals through the messenger about their vote to attack or retreat, so that each general can know the common voting result and decide the action strategy based on his vote and the information sent by all other generals.

The problem is that there may be traitors among generals. They may not only vote for worse strategies, but they may also selectively send voting information. Suppose there are 9 generals voting, and 1 of them is a traitor. Among the 8 loyal generals, 4 attacked and 4 evacuated. At this time, the traitor may deliberately send letters to the 4 generals who voted to vote to attack, and send letters to the 4 generals who voted to leave to vote to leave. In this way, in the eyes of the 4 generals who voted for the attack, the result of the vote was that 5 people voted for the attack, thus launching the attack; while for the 4 generals who voted for the retreat, it was 5 people who voted for the evacuation. In this way, the unity and coordination of the various armies was destroyed.

Since the generals need to communicate through messengers, the rebel generals may send fake votes as other generals by forging letters. And even when the loyalty of all generals is guaranteed, it cannot be ruled out that the messenger is intercepted and killed by the enemy, or even replaced by the enemy spy. Therefore, it is difficult to solve the problem by ensuring the reliability of personnel and communication.

If those loyal (or error-free) generals can still decide their strategy by majority decision, it is said to have reached Byzantine fault tolerance. Here, the votes will have a default value. If the message (ticket) is not received, the default value will be used to vote.

40. How to realize decentralization and distributed ledger?

Realize decentralization

In the Bitcoin white paper "Bitcoin: A Peer-to-Peer Electronic Cash System", Satoshi Nakamoto explained in detail how he designed this systematic. In it, he established the main design principles of all blockchain systems since then.

(1) A true peer-to-peer electronic cash should allow direct online payment from the originator to the other party without going through a third-party financial institution.

(2) Although the existing digital signature technology provides a partial solution, if a trusted third-party institution is needed to prevent (electronic cash) "double payment", it will be lost The main benefit (from electronic cash).

(3) Aiming at the "double payment" problem in electronic cash, we use peer-to-peer network technology to provide a solution.

(4) The network timestamps transaction records, and after hashing the transaction records, it is merged into a growing chain, which is hashed The hash-based proof-of-work is composed of the listed hash-based proof-of-work. If the proof-of-work is not redone, the record formed by this cannot be changed.

(5) The longest chain is not only a proof of the observed sequence of events, but also that it is produced by the largest pool of CPU processing power. As long as the computer nodes that control most of the CPU processing power do not unite (with the attacker) to attack the network itself, they will generate the longest chain, leaving the attacker behind.

The network itself only needs the simplest structure. The information can be broadcast on the whole network as much as possible. A node can leave and rejoin the network at any time, as long as (when rejoining) the longest proof-of-work chain is used as the proof of the transactions that occurred during the offline period of the node.

41. Can quantum computers destroy Bitcoin?

Can a big quantum computer become a Bitcoin killer? Microsoft's research shows that the qubits required to unravel the discrete logarithm of the elliptic curve are less than the 2048-bit RSA that requires 4000 qubits. However, these are perfect "logical" qubits. Due to error correction and other necessary steps, we need more physical qubits. John Preskill mentioned in his quantum information lecture that a standard 256-bit key requires approximately 2500 qubits, and cracking this key requires a quantum computer with 10 million physical qubits and 10,000 logical qubits.

The current quantum technology is still far from this milestone. IBM announced that they had realized a 50-qubit system at the end of 2017; Google announced the realization of 72 qubits at the beginning of 2018; IonQ, which uses ion traps, released a quantum computer with 160 qubits and compared 79 of them. The qubit performed the calculation; DWave released its own 2048 qubit system, however, it is a quantum softening device and cannot be used in Shor's algorithm.

The ultimate goal is to build a large enough quantum computer for chemistry, optimization, and machine learning. However, although large quantum computers that can perform these tasks are still out of reach, cryptocurrencies in circulation may be affected by such quantum computers in the future.

42. Does the code of the blockchain project need to be open source? why?

Blockchain is a consensus mechanism, which means that such participants must be transparent, that is to say, this kind of running code must be open source code, the so-called open source code is The code is visible.

Everyone can compile and execute their own compiled program, which means that everyone can modify the code and run it. Under the current mechanism, it is possible to modify the code no matter how, as long as these people modify the code If it doesn't exceed 51%, then this kind of modification is meaningless, and it wastes one's own computing power.

So, at least the people involved must know the code. If a blockchain project, the code is not open source, then the nodes running his program are opaque, which is equivalent to you The agent of is installed on his own node and is about to execute the order on behalf of this owner. It is equivalent to the system developer controlling the entire network. How is this kind of blockchain feasible?

From a conceptual point of view, if a blockchain project is compared to a machine, its working mechanism is transparent and a machine that can be trusted. This is understood in this way. First, open source is a required option for blockchain projects, not optional. Both public chains and alliance projects need to be open source; second, open source and delivery of source code are two Different concepts, the delivery of source code is not an open and transparent process that everyone participates in.

For example, in Ethereum, there was a loophole in a certain platform currency running on its platform and needed to be modified. This modification is directly reflected in the code. In the process of reading the code, I found that there are multiple related codes of the coin, which are used to deal with this problem, how the node should deal with it, these processing methods are written in the open source code, everyone can read it, if the person in charge of the node approves With this solution, he will run the program, which is equivalent to a decision to support this code. In fact, the blockchain is implemented through this mechanism.

*For more detailed analysis, you can download the Link Dede App to see related analysis articles, such as

"[Dede Analysis] Open the code "black box", the alliance chain is no longer "circle" The Self-Union""

3. Digital Assets

43. What is the relationship between encrypted digital currency and blockchain?

Encrypted digital currency usually refers to a digital asset issued on a blockchain network. Through the blockchain browser, users can query the entire process of digital currency transactions. In life, we often refer to the digital assets issued by blockchain institutions or project parties as "encrypted digital currency", which is fundamentally different from the digital currency issued by the central bank, namely: the central bank digital currency is a substitute for M0, itself No new currency is issued; the digital currency issued by the blockchain project party "created" a currency out of thin air, lacking the endorsement of sovereign institutions, and there is a greater credit risk.

From the point of view of definition, blockchain is a new form of technology, which has the characteristics of transparency, traceability, and non-tamperability, which can empower industries such as supply chain finance, product traceability, and certification. field. Through the blockchain, a reliable value network can be established.

44. Is the currency market the same as the stock market?

The currency market is different from the stock market, but the currency market often draws on the trading logic of the traditional secondary stock market. From a formal point of view, both the currency market and the stock market will experience fundraising in the primary market and transactions in the secondary market. However, there are many differences between them, which are mainly reflected in the following aspects:

(1) Different issuance methods: coins are issued through the blockchain, there is a total amount of settings, no additional issuance, and accompanied by a destruction mechanism , Most of them belong to "deflationary" currencies; stocks are securities assets issued by companies through stock exchanges, which do not have currency attributes, and are income-based assets. The value of shares is determined by the number of shares held * stock price; /p>

(2) Different trading methods: Encrypted digital currencies can be launched on multiple digital currency exchanges at the same time, and can be traded 7*24 hours, and companies that issue securities for the first time often choose a stock exchange to issue stocks. The market will be closed on holidays;

(3) Different supervision: The currency market is still in a state of no supervision, no authoritative and independentRegulators, the issuance of encrypted digital currency is to a greater extent a personal will; and the global stock market will have official regulatory agencies such as the Securities Regulatory Commission, which often play a role in market supervision and prevention of financial risks.

(4) Different functions: In addition to being used for secondary market transactions, coins can also be used for daily consumption and purchase of related business products. According to different functions, coins can be divided into functional, security and Commodity type, Bitcoin is a typical commodity type; and stocks generally refer to securities, which can only be used for transfers and transactions in the primary or secondary market. At present, various countries are also exploring a classified supervision model, and supervise the securities-type currency as the stock and securities market.

45. What is the central bank's digital currency? Can ordinary people use it? How to get it?

The digital currency issued by the central bank can be understood as "the digitization of the renminbi", which is a substitute for the renminbi M0, which is the currency for daily consumption in circulation. The issuance of central bank digital currency can directly solve the loss of paper currency in the issuance, printing, withdrawal, storage and other links, and "digitization" can make RMB transactions more convenient, safer, and feature anonymity. Digitalization can provide greater convenience for the RMB in international trade transactions.

The central bank's digital currency is a "two-tier operating structure", that is, the People's Bank of China first exchanges the digital currency to banks or other operating institutions, and then these institutions exchange them to the public. The common people can directly exchange the central bank's digital currency through commercial banks or other institutions and can directly use it in daily consumption.

The main difference with Bitcoin is that the central bank’s digital currency is endorsed by national sovereignty and has an equivalent amount of renminbi reserve assets behind it; but Bitcoin is a non-sovereign encrypted digital asset, which passes " "Mining" will produce a total of 21 million pieces, and the production will be cut in half every four years, which has obvious "deflationary" characteristics.

* Linkdede has conducted many discussions and researches on central bank digital currency issues. For more details, you can download the Linkdede App, for example:

46. What are the currently active digital currency exchanges in China and who are the main operating entities?

At present, the Chinese government has a negative attitude towards digital currency exchanges and has not yet issued a clear regulatory policy. Therefore, most exchanges are registered overseas in name, but the actual operating entities and actual platform users are all in China, and some exchanges are also registered in China. Due to unclear policies, most of the operating entities are private companies or individuals, including some blockchain media trying to open exchanges. However, the media opening exchanges may face greater risks, which can easily lead to risks from manipulation of information to manipulation of the market.

47. Will digital currency replace the current physical currency in the future?

Due to the high cost, easy loss, low safety factor, and difficulty of traceability in paper currency, there are many cases of money crime. In today's society, "digitalization" has become a trend, and physical currency can improve the safety factor of the currency and the convenience of transactions through the realization of electronicization. Undoubtedly, digital currency with national sovereign credit endorsement and equivalent financial asset mortgage will become a new form of currency in the future

48. Digital currency will affect the existing financial system What are the effects?

The definition of "digital currency" needs to be clear. The digital currency issued by the central bank should not be confused with the digital currency issued by Bitcoin, Ethereum or other blockchain projects. From the perspective of preventing financial risks, the central bank’s digital currency is a digital supplement to currency, and does not essentially affect the issuance, acceptance and circulation of RMB; however, the digital currency issued by Bitcoin, Ethereum, and blockchain projects Currency, because of its characteristics of internationalization and anonymity, will have problems such as the loss of state-owned assets, money laundering transactions, and black market transactions, which will have a huge impact on the stability of the financial system.

49. Ordinary people buy cryptocurrency, do they need real-name authentication in the future?

In the case of Bitcoin, it is produced through "mining". Ordinary people can create a Bitcoin wallet and form a unique blockchain wallet address. The Bitcoin they receive Will be stored in the wallet, and real-name authentication is not required. However, a trading venue that provides trading and circulation for bitcoin and other encrypted digital currencies has been formed. Users can conduct secondary market transactions through trading venues such as Binance, Huobi, and Coinbase, and buy and sell bitcoins.Secret digital currency. For these trading venues, they often require users to perform strict real-name authentication, mainly to achieve controllable risks.

50. Can ordinary people participate in mining and how to mine?

"Mining" is actually a calculation program, and the mining program is essentially a process of keeping accounts. In the case of Bitcoin, the total issuance of 48 million pieces is halved every four years. During the production process, a block will be packaged every 10 minutes. Which "miner" grabs the right to pack this block will also It is to grab the right to keep the account and obtain the reward of the packaged block. The blocks are connected to form a "block chain".

"Mining" is mainly carried out by running an accounting program on a computer. Ordinary computers can run this program, but as the number of miners increases, the difficulty of mining increases, which requires a higher-performance graphics card to support computing. Therefore, professional ASIC graphics mining machines have become a market demand, and mining has gradually evolved from a history of personal participation to a professional behavior, and mining farms have also been born.

From the current point of view, ordinary people can participate in mining by investing in mining machines and managed by the mine; they can also indirectly mine by purchasing cloud computing power.

51. Do all currencies need to be produced by mining?

This is determined by different consensus mechanisms. Bitcoin adopts the PoW model, that is, "Proof of Work", which means that the more computational work you put in, the easier it is for you to obtain the accounting rights for block packaging, and the more opportunities you have for rewards.

Since then, PoS, DPow and other mechanisms have also been born on the market, which all contain different mining rules. However, for the encrypted digital currency issued by many project parties, it does not need to be generated by mining. It is essentially the issuance of a tradable digital asset out of thin air, which can be realized through lock-up, market launch, transaction, etc. Circulation and transfer.

52. What is the nature of the value of digital currency?

It is essentially a decentralized, transparent and secure digital asset. It runs a program to automatically realize the issuance of assets without the intervention of any organization or institution. The value of currency is based on people's trust, but at the same time it is affected by the relationship between supply and demand. But transactions are based on people's needs for reality and judgments about future value. In the same way, Bitcoin was originally intended as a currency that can be used for payment, but the huge volatility of its price determines that it cannot be used for transactions.

Since then, Bitcoin has been regarded as a stored-value asset. From the perspective of the situation, production is reduced once every six months, and the number of users holding Bitcoin is increasing. It seems that most people are optimistic. The future value-added space of Bitcoin. But from the perspective of supply and demand structure, if people are optimistic about Bitcoin, they will not choose to sell Bitcoin. If there is no seller in the market, Bitcoin will not have a market and naturally there will be no value. This seems to be a contradiction that is difficult to explain.

53. What should I do if I personally want to send a coin of my own?

Starting September 4, 2017, all related ICO (digital currency issuance) activities are prohibited in China. And repeatedly reiterated the huge risks of "coin speculation". It is currently strictly prohibited by Chinese law.

54. What should I pay attention to when mining?

You need to consider the loss of the mining machine, the cost of electricity, and the computing power of the entire network. In terms of mining machine loss, professional graphics card mining machines have advantages in terms of lifespan, efficiency, and electricity cost, and the size of the entire network's computing power means how many "miners" are currently mining with mining machines. For many mines, they are built by water to find cheaper electricity costs, so as to maximize their profits.

55. Do the coins produced by mining have transaction value?

"Transaction value" is relatively speaking. If there are enough buyers and sellers, the liquidity of the transaction can be formed, and a counterparty with transaction value can be formed. In fact, whether it is the mined coin or the token issued by the blockchain project party, as long as it has liquidity in the secondary market, it also has "transaction value". However, whether these coins have value in themselves is worthy of more discussion.

56. What kind of encrypted wallet is the safest? What kind of wallet is the most convenient?

Encrypted digital currency wallets are mainly divided into "cold wallets" and "hot wallets"."Wallet". "Cold wallet" is an offline wallet, which can also be understood as a hardware wallet that is not connected to the Internet. It is like a safe at home. A "hot wallet" is a networked wallet that can conduct real-time transactions over the Internet.

In terms of safety factor, cold wallets are the safest. Hackers cannot steal encrypted digital assets stored in cold wallets through network attacks. From the perspective of transaction convenience, hot wallets are the most convenient, and they can be accessed through APP , Computer webpages or clients to conduct online transactions and storage. At present, mainstream cryptocurrency exchanges all use the "cold + hot" wallet configuration model, large assets are stored in cold wallets, and assets available for circulating transactions are stored in hot In the wallet.

57. How to store and trade bitcoins?

Storage: Users can store bitcoins in their encrypted digital currency wallets, All mainstream wallets support Bitcoin deposits and withdrawals. Users can also deposit Bitcoins in encrypted digital currency exchanges, and the exchanges will take care of them.

Transaction: Bitcoin transactions are divided into "fields" On-site trading and over-the-counter trading". On-exchange trading, through the encrypted digital currency exchange to place orders, that is, "secondary market trading" in the popular sense; over-the-counter trading: by looking for a counterparty, the two parties can achieve face-to-face or point-to-point The transaction, that is, the Bitcoin transaction is realized directly through the wallet address transfer.

But before the Bitcoin transaction, in addition to mining or other people directly gifting the Bitcoin, you need to purchase the Bitcoin through legal currency Currency. Users can use the over-the-counter market to give legal currency to the individual who holds Bitcoin, and this person transfers the Bitcoin to your Bitcoin account.

58. On the blockchain Does the transaction require a fee? How is it determined? How much is determined by who?

Transactions on the blockchain require a fee. From the principle point of view, the transaction process is also the miner packaging During the process, miners will choose to package the transaction and publish it on the entire network only if the user pays the fee. The size of the fee mainly depends on the current difficulty of the entire network.

When the entire network When the computing power reaches a peak, users often need more fees to attract miners to prioritize the packaging of the transaction. The faster the packaging, the faster the transaction speed. Conversely, when the competition for computing power across the network is not so great At the time, users can quickly be packaged and traded by miners even if they pay a small fee.

59. How does a Bitcoin transaction count as a successful transaction?

After the Bitcoin transaction data is packaged into a "data block" or "block", the transaction is considered to be initially confirmed. When the block is linked to the previous block, the transaction will be further confirmed. After 6 consecutive block confirmations, the transaction is basically confirmed irreversibly. The Bitcoin peer-to-peer network stores all transaction history in "Blockchain" (blockchain). The blockchain continues to extend, and once new blocks are added to the blockchain, they will no longer be removed.

When we submit a transaction, under normal circumstances, the transaction will eventually be put in a certain block by the miners. At this time, we can say that this transaction has received 0 confirmations. When there is another blockchain to this exchange in the block, that is, when the exchange is in the block as the parent block, we say that the transaction has received 1 confirmation, and so on. The number of confirmations for a transaction is how many blocks the exchange has linked to behind the block.

60. What kind of digital currency is Libra launched by Facebook? Is it related to the blockchain?

Libra is a cryptocurrency proposed by Facebook. It is planned to be issued in 2020. However, due to many disputes, this plan is temporarily suspended. Libra is a stable currency, which is a classification of cryptocurrencies in the digital cryptocurrency industry.

According to the white paper, Libra runs on the Libra Blockchain. It is a goal to become a global financial infrastructure. It can be extended to billions of accounts and supports high transaction throughput. In other words, the capacity of this blockchain is sufficient to support the transaction volume of billions of people around the world.

* Stable currency related content can be downloaded from the Link Dede App, see for example

"[Chain De Depth] Analysis of 59 mainstream stable currencies in the world, "Oligarchic market" next Where is the opportunity? 》

61.ICO, STO, IEWhat is O?

ICO (Initial Coin Offering), refers to the first token issuance of a blockchain project to the public, raising mainstream cryptocurrencies such as Bitcoin and Ethereum to obtain the operation of the project Funding.

IEO (Initial Exchange Offerings), first trade offering, refers to the issuance of tokens with exchanges as the core; tokens skip the ICO step and go directly to the exchange.

STO (Security Token Offering) issuance of securitization tokens refers to the issuance of securities laws governing the company’s equity, debt, gold, real estate investment trusts, and the dividend rights of the blockchain system as the corresponding tokens. Public issuance of certificates.

*What is the difference between ICO and IEO? For more details, please refer to the article on Link Dede:

"[Dede Vernacular] From ICO to IEO, everything will never change"

62. Dark web, encrypted currency What is the relationship with the blockchain?

The dark web is the Internet content that exists on the dark web and the overlay network. It can only be accessed with special software, special authorization, or special settings on the computer. Because transactions on the dark web often use cryptocurrencies that can be anonymous, the two are often compared. The dark web has no direct relationship with blockchain technology.

63. How to distinguish between public chain, private chain, and alliance chain?

The public chain refers to a consensus blockchain that anyone in the world can read and send transactions but can be effectively confirmed. In other words, the behavior on the public chain is open and transparent, not controlled by anyone, nor owned by anyone, and is a "completely decentralized" blockchain.

The private chain is open to individual individuals or entities, and is only used by private organizations, such as the company's internal use. The read and write permissions on the private chain and the permissions to participate in accounting are all set by the private organization.

Consortium chain refers to a blockchain that is managed by several institutions. Each institution runs one or more nodes, and the data in it only allows different institutions in the system to read, write and send Transactions, and together to record transaction data. Therefore, the read and write permissions and accounting rules on the alliance chain are "privately customized" according to the alliance rules.

* How does the consortium chain land? For more details, download the Chain Dede App for more explanations, please refer to the article on Chain Dede.

Question 64-Question 100, please

click to view "Chain Dede" Blockchain "100 Questions" blockbuster release: Encyclopedia of Blockchain Literacy Reader (Part 2)"

This article is the first part of "Chainde "100 Questions on Blockchain", scan the top Follow the chain's WeChat ID (WeChat ID: ChainDD) with the picture QR code, and reply to "Blockchain 100 Questions" to get the full PDF electronic version of "Blockchain 100 Questions", or click the link to download the full PDF report content.

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Label group:[digital currency] [blockchain] [Bitcoin transactions] [Chinese currency] [Digital technology] [mining] [mining machine] [accounting software] [bitcoin block] [Network node] [Decentralized

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