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⑴ Four consensus mechanisms of blockchain
The consensus mechanism of blockchain can be divided into the following four categories: Proof of Stake mechanism, Proof of Work mechanism, Pool verification and Pool share authorization certification mechanism.
Blockchain is a chain composed of blocks one after another. Each block stores a certain amount of information, and they are connected into a chain in the order in which they were generated. This chain is saved in all servers. As long as one server in the entire system can work, the entire blockchain is safe. These servers are called nodes in the blockchain system, and they provide storage space and computing power support for the entire blockchain system.
⑵ Consensus mechanism of blockchain
1. The goal of consensus mechanism of blockchain
What is blockchain? Simply put, blockchain is a decentralized database, or it can be called a distributed ledger. Traditionally, all databases are centralized. For example, a bank's ledger is stored in the bank's central server. The disadvantage of a centralized database is that the security and accuracy of the data depend entirely on the database operator (i.e., the bank), because anyone who has access to the centralized database (such as bank employees or hackers) can destroy or modify the data in it.
Blockchain technology allows databases to be stored on thousands of computers around the world. Everyone’s ledger is synchronized through a peer-to-peer network, and anyone in the network can Once a user adds a transaction, the transaction information will be notified to other users through the network for verification and recorded in their respective ledgers. Blockchain gets its name because it is a data structure composed of blocks containing transaction information linked in an orderly manner from back to front.
Many people’s question about blockchain is that if each user has an independent ledger, does it mean that they can add to their own ledger? Arbitrary transaction information, and how can thousands of ledgers ensure the consistency of accounting? Solving the problem of accounting consistency is the goal of the blockchain consensus mechanism. The blockchain consensus mechanism aims to ensure that the data in all nodes in the distributed system are exactly the same and can reach agreement on a certain proposal (for example, a transaction record). However, due to the introduction of multiple nodes in a distributed system, various very complex situations will occur in the system; as the number of nodes increases, node failure or failure, network communication between nodes is interfered or even blocked, etc. In addition to common problems, solving various boundary conditions and unexpected situations in distributed systems also increases the difficulty of solving distributed consistency problems.
Blockchain can be divided into three types:
Public chain: full Anyone in the world can enter at any timeEnter the system to read data, send transactions that can be confirmed, and compete for accounting in the blockchain. Public blockchains are generally considered "completely decentralized" because no one or institution can control or tamper with the reading and writing of data. Public chains generally encourage participants to compete for accounting through a token mechanism to ensure data security.
Alliance chain: Alliance chain refers to a blockchain in which several institutions jointly participate in management. Each institution runs one or more nodes, and the data in it only allows different institutions within the system to read, write and send transactions, and jointly record transaction data. This type of blockchain is considered “partially decentralized.”
Private chain: refers to a blockchain whose write permission is controlled by an organization or institution. The qualifications of participating nodes will be strictly restricted. Since the participating nodes are limited and controllable, private chains can often have extremely fast transaction speeds, better privacy protection, lower transaction costs, and are not prone to malicious attacks. , and can meet the necessary requirements of the financial industry such as identity authentication. Compared with centralized databases, private chains can prevent single nodes within an organization from deliberately concealing or tampering with data. Even if an error occurs, the source can be quickly discovered, so many large financial institutions are currently more inclined to use private chain technology.
2. Classification of blockchain consensus mechanisms
The difficulty of solving distributed consistency problems has given rise to several consensus mechanisms, each of which has its own advantages and disadvantages, and is also suitable for different environment and issues. The consensus mechanisms that are common knowledge include:
l PoW (Proof of Work) workload proof mechanism
l PoS (Proof of Stake) ) Equity/Equity Proof Mechanism
l DPoS (Delegated Proof of Stake) Share Authorization Proof Mechanism
l PBFT (Practical Byzantine Fault Tolerance) Practical Byzantine Fault Tolerance Algorithm
l DBFT (Delegated Byzantine Fault Tolerance) Authorized Byzantine Fault Tolerance Algorithm
l SCP (Stellar Consensus Protocol) Stellar Consensus Protocol
l RPCA (Ripple Protocol Consensus Algorithm) Ripple Consensus Algorithm
p>l Pool verification pool consensus mechanism
(1) PoW (Proof of Work) workProof of Work Mechanism
1. Basic Introduction
In this mechanism, the network Every node on the network is using the SHA256 hash function to calculate the hash sum of a constantly changing block header. Consensus requires that the calculated value must be equal to or less than a given value. In a distributed network, all participants need to continuously calculate the hash value using different random numbers until the goal is reached. When one node calculates an exact value, all other nodes must confirm with each other that the value is correct. Transactions in new blocks will then be verified to prevent fraud.
In Bitcoin, the above nodes that calculate hash values are called "miners", and the PoW process is called "mining". Mining is a time-consuming process, so incentives have been proposed (such as granting miners a small share of Bitcoin). The advantage of PoW is complete decentralization, but its disadvantage is the waste of resources caused by consuming a lot of computing power, the cycle of reaching consensus is also relatively long, and the consensus efficiency is low, so it is not very suitable for commercial use.
2. Application examples of cryptocurrency
Bitcoin and Litecoin. The first three phases of Ethereum (Frontier, Homestead, and Metropolis) all adopt the PoW mechanism, and its fourth phase (Serenity) will adopt the proof-of-stake mechanism. PoW is suitable for public chains.
Although the PoW mechanism has successfully proved its long-term stability and relative fairness, under the existing framework, using the "mining" form of PoW will consume A lot of energy. The energy it consumes is just to continuously perform SHA256 calculations to ensure fair workload, and has no other meaning of existence. The current transaction efficiency that BTC can achieve is about 5TPS (5 transactions/second). Ethereum is currently subject to the upper limit of the total amount of GAS in a single block, and the transaction frequency that can be achieved is about 25TPS, which is the same as the average thousand times per second and peak performance. There is a huge difference between VISA and MASTERCARD, which can achieve processing efficiency of 10,000 times per second.
3. Simple diagram understanding mode
(ps: The process of calculating hash values by A, B, C, and D is “mining"Mining", in order to reward the time cost, the mechanism will use a certain number of Bitcoins as incentives.)
(Ps: In PoS mode, your " "Mining" income is proportional to your coin age (number of coins * number of days), and has nothing to do with the computing performance of the computer. We can think of any accumulation of probabilistic events as proof of work, such as gold mining. Assume that the gold content of the ore is p % quality, when you get a certain amount of gold, we can think that you must have dug 1/p quality ore. And the more gold you get, the more reliable this proof is.)
(2) PoS (Proof of Stake) Equity/Proof of Equity Mechanism
1. Basic Introduction
PoS requires people to prove ownership of the currency amount, and it believes that people with a large amount of currency are less likely to attack the network. Selection based on account balance is very unfair, because the single richest People who are bound to dominate the network, so many solutions have been proposed.
In the proof-of-stake mechanism, every time a block is created, miners A transaction called "coin rights" needs to be created. This transaction will pre-send some coins to miners according to a certain proportion. Then the equity proof mechanism is based on the proportion and time (coin age) of the tokens held by each node, based on the algorithm, etc. Proportionally reduce the mining difficulty of the node to speed up the node's search for random numbers and shorten the time required to reach consensus.
Compared with PoW, PoS It can save more energy and be more efficient. However, since the mining cost is close to 0, it may be attacked. And PoS still essentially requires nodes in the network to perform mining operations, so it is also difficult to apply to the commercial field. .
2. Application examples of digital currency
The more mature digital currencies under the PoS mechanism are Peercoin and NXT. Compared with PoW, the PoS mechanism saves energy and introduces the concept of "coin days" to participate in random operations. The PoS mechanism allows more currency holders to participate in the accounting work without the need to purchase additional equipment (mining machines, graphics cards, etc.). The computing power of each unit token is positively related to the length of time it is held. That is, the more tokens a holder holds and the longer the time, the greater the probability that it can sign and produce the next block. Once it signs the next block, the number of coins held by the token holder will be Clear and re-enter the new cycle.ring.
PoS is suitable for public chains.
3. How to generate block signers
Under the PoS mechanism, Because the signers of blocks are randomly generated, some currency holders will hold tokens for a long time and in large amounts to obtain a greater probability of generating blocks, and to clear as many of their "coin days" as possible. Therefore, the number of circulating tokens in the entire network will decrease, which is not conducive to the circulation of tokens on the chain, and prices will be more susceptible to fluctuations. Since there may be a small number of large investors holding most of the tokens in the entire network, the entire network may become more and more centralized as the running time increases. Compared with PoW, the cost of doing evil under the PoS mechanism is very low, so for forking or double-spending attacks, more mechanisms are needed to ensure consensus. Under stable conditions, approximately 12 transactions can be generated per second, but due to network delays and consensus issues, it takes about 60 seconds to fully broadcast the consensus block. In the long run, the speed of generating blocks (that is, clearing "coin days") is much lower than the speed of network propagation and broadcasting. Therefore, under the PoS mechanism, it is necessary to "limit the speed" of generated blocks to ensure the stability of the main network. run.
4. Simple diagram understanding mode
(PS: The more “shares” you own, the easier it is for you to obtain account rights. It refers to how much currency you get, which depends on the workload you contribute to mining and the performance of your computer. The better, the more mines will be allocated to you.)
(In a pure POS system, such as NXT, there is no mining process, and the initial equity The distribution has been fixed, and then only the equity is transferred among traders, very similar to stocks in the real world.)
(3) DPoS (Delegated Proof of Stake) ) Share authorization certification mechanism
1. Basic introduction
Due to various disadvantages of PoS , thus the DPoS (Delegated Proof of Stake), the first equity representation mechanism pioneered by BitShares, came into being. The core element of the DPoS mechanism is election. Holders of each system's native tokens can participate in elections in the blockchain, and the balance of the tokens they hold is the voting weight. Through voting, shareholders can elect board members and express their attitudes on issues related to the development direction of the platform.the basis of governance. In addition to voting in elections themselves, shareholders can also vote on their behalf by authorizing their election votes to other accounts they trust.
Specifically, DPoS was invented by the Bitshares project team. Stakeholders elect their representatives to generate and verify blocks. DPoS is similar to a modern corporate board of directors system. The BitShares system calls token holders shareholders, and shareholders vote to elect 101 representatives. These representatives are then responsible for generating and verifying blocks. If a currency holder wants to be called a representative, he must first use his public key to register on the blockchain and obtain a unique 32-bit identity identifier. Shareholders can vote on this identifier in the form of transactions and get votes. The top 101 people were selected as representatives.
Representatives take turns to generate blocks, and the profits (transaction fees) are equally divided. The advantage of DPoS is that it greatly reduces the number of nodes participating in block verification and accounting, thereby shortening the time required for consensus verification and greatly improving transaction efficiency. From a certain perspective, DPoS can be understood as a polycentric system, which has the advantages of both decentralization and centralization. Advantages: It greatly reduces the number of nodes participating in verification and accounting, and can achieve second-level consensus verification. Disadvantages: Voting enthusiasm is not high, and most token holders do not participate in voting; in addition, the entire consensus mechanism still relies on tokens, and many commercial applications do not require the existence of tokens.
The DPoS mechanism requires that before generating the next block, it must be verified that the previous block has been signed by a trusted node. Compared with PoS's "National Mining", DPoS uses a system similar to the "Congress" to directly select trusted nodes, and these trusted nodes (i.e. witnesses) exercise power on behalf of other currency holders. Witnesses Nodes are required to be online for a long time, thus solving a series of problems such as delays in block production that may be caused by PoS block signers not always being online. The DPoS mechanism can usually reach a transaction speed of 10,000 transactions per second, and can reach the level of 100,000 seconds when the network delay is low, which is very suitable for enterprise-level applications. Because Gongxinbao Data Exchange has high requirements for data transaction frequency and long-term stability, DPoS is a very good choice.
2. Institutions and systems under the share authorization certification mechanism
The board of directors is the authority of the blockchain network. The candidates for the board of directors are elected by system shareholders (i.e. currency holders). Board members have the right to initiate motions and vote on motions.
One of the important responsibilities of the Board of Directors is to adjust the variable parameters of the system as needed. These parameters include：
l Fee related: rates for various transaction types.
l Authorization related: parameters related to charges and subsidies for third-party platforms that access the network.
l Block production related: block production interval, block reward.
l Identity review related: review and verify the information of abnormal institutional accounts.
l At the same time, matters related to the interests of the Board of Directors will not be set by the Board of Directors.
In the Finchain system, witnesses are responsible for collecting various transactions broadcast when the network is running and packaging them into blocks. Their work is similar to that of the Bitcoin network In the Bitcoin network that adopts PoW (Proof of Work), a lottery method in which the probability of winning depends on the hash power determines which miner node generates the next block. In a financial chain network that adopts the DPoS mechanism, the number of witnesses is determined by voting by the board of directors, and the candidates for the witnesses are determined by voting by currency holders. The selected active witnesses package transactions and produce blocks in order. After each round of block production, the witnesses will randomly shuffle the cards to determine the new order before entering the next round of block production.
3. Application examples of DPoS
Bitshares uses DPoS. DPoS is mainly suitable for alliance chains.
4. Simple diagram understanding mode
(4) PBFT (Practical Byzantine Fault Tolerance) Practical Byzantine Fault Tolerance Algorithm
1. Basic introduction
PBFT is an algorithm based on strict mathematical proof, which requires three stages of information interaction and local consensus to achieve the final unanimous output. The three stages are pre-prepare, prepare, and commit. The PBFT algorithm proves that as long as there are more than 2/3 normal nodes in the system, it can ensure that a consistent consensus result can be output in the end. In other words, in a system using the PBFT algorithm, it can tolerate no more than 1/3 of the total number of nodes in the system (including intentional misleading, intentional system damage, timeout, repeated message sending, forgery, etc.)Nodes such as signatures, also known as "Byzantine" nodes).
2. Application examples of PBFT
The famous alliance chain Hyperledger Fabric v0.6 uses PBFT, and v1.0 launched an improved version of PBFT, SBFT. PBFT is mainly suitable for private chains and consortium chains.
3. Simple diagram understanding mode
The above figure shows a simplified PBFT protocol communication model, where C is the client, 0 – 3 represents the service node, where 0 is the master node and 3 is the fault node . The basic process of the entire protocol is as follows:
(1) The client sends a request to activate the service operation of the master node;
(2) When the master node receives the request, it starts a three-phase protocol to broadcast the request to each slave node;
(a) Sequence number allocation phase, the master node assigns a sequence number n to the request, broadcasts the sequence number allocation message and the client's request message m, and will construct a pre-prepare message to each slave node;
(b) In the interaction phase, the slave node receives the pre-prepare message and broadcasts the prepare message to other service nodes;
(c) In the sequence number confirmation phase, after each node verifies the request and sequence in the view, it broadcasts the commit message, executes the received client request and responds to the client.
(3) The client waits for responses from different nodes. If m+1 responses are the same, the response is the result of the operation;
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(5) DBFT (Delegated Byzantine Fault Tolerance) authorized Byzantine fault tolerance algorithm
1. Basic introduction
DBFT is based on PBFT. In this mechanism, there are two types of participants, one is the "super node" who specializes in accounting , one is an ordinary user in the system who does not participate in accounting. Ordinary users vote for super nodes based on the proportion of their equity holdings. When a consensus (accounting) needs to be passed, a spokesperson is randomly selected among these super nodes to formulate a plan, and then other super nodesNodes take positions according to the Byzantine Fault Tolerance algorithm (see above), i.e. the majority rule. If more than 2/3 of the super nodes agree with the speaker plan, a consensus is reached. This proposal becomes the final published block, and the block is irreversible, and all transactions in it are 100% confirmed. If a consensus proposal has not been reached within a certain period of time, or if illegal transactions are discovered, other super nodes can reinitiate the proposal and repeat the voting process until a consensus is reached.
2. Application examples of DBFT
NEO, a domestic cryptocurrency and blockchain platform, is the developer and adopter of the DBFT algorithm.
3. Simple diagram understanding mode
Assume that there are only four super nodes in the system voted by ordinary users. When a consensus needs to be passed, the system will randomly select one of the representatives to speak. People make plans. The spokesperson will hand over the prepared plan to each representative. Each representative will first determine whether the speaker's calculation results are consistent with their own records, and then discuss with other representatives to verify whether the calculation results are correct. If 2/3 of the representatives unanimously agree that the calculation results of the speaker's plan are correct, then the plan is passed.
If less than 2/3 of the representatives reach a consensus, a new speaker will be randomly selected and the above process will be repeated. This system is designed to protect the system from leaders who are unable to function.
The above figure assumes that all nodes are honest and reach 100% consensus, and plan A (block) will be verified.
Given that the spokesperson is a randomly selected representative, he may be dishonest or malfunctioning . The above figure assumes that the spokesperson sends malicious messages to 2 of the 3 representatives (scenario B), and at the same time sends a correct message to 1 representative (scenario A).
In this case, the malicious information (Option B) cannot pass. The calculation results of the representatives in the middle and on the right were inconsistent with those sent by the spokesperson, so they could not verify the plan drawn up by the spokesperson, causing the two people to reject the plan. The representative on the left received correct information that was consistent with his own calculation results, so he was able to confirm the plan and successfully completed a verification. However, this plan still failed to pass because less than 2/3 of the representatives reached a consensus. ThenA new speaker is randomly selected and the consensus process starts over.
The above picture assumes that the speaker is honest, but One of the representatives experienced an anomaly; the representative on the right sent incorrect information to the other representatives (B).
In this case, the correct information (A) formulated by the speaker can still be verified, because both the honest representatives on the left and the middle can verify that the correct information (A) formulated by the spokesperson The plan drawn up by the spokesperson reached a 2/3 consensus. The representative can also determine whether the speaker is lying to the node on the right or the node on the right is being dishonest.
(6) SCP (Stellar Consensus Protocol) Stellar Consensus Protocol
1. Basic introduction
SCP is a consensus algorithm developed and used by Stellar (a decentralized global payment protocol based on the Internet). It is based on the Federated Byzantine Agreement ( Federated Byzantine Agreement). Although traditional non-federated Byzantine protocols (such as PBFT and DBFT above) ensure that consensus can be reached through distributed methods and achieve Byzantine fault tolerance (can tolerate at most failed nodes that do not exceed 1/3 of the total number of nodes in the system), it is a Centralized system - The number and identity of nodes in the network must be known and verified in advance. The difference of the Federated Byzantine Agreement is that it can be decentralized and Byzantine fault-tolerant at the same time.
[…]
(7) RPCA (Ripple Protocol Consensus Algorithm) Ripple Consensus algorithm
1. Basic introduction
RPCA is Ripple (an Internet-based Open source payment protocol, which can realize decentralized currency exchange, payment and settlement functions) consensus algorithm developed and used. In Ripple's network, transactions are initiated by the client (application) and broadcast to the entire network through the tracking node or validating node. The main function of the tracking node is to distribute transaction information and respond to client ledger requests. The verification node containsIn addition to all the functions of the tracking node, it can also add new ledger instance data to the ledger through the consensus protocol.
Ripple's consensus occurs between verification nodes. Each verification node is pre-configured with a list of trusted nodes, called UNL (Unique Node). List). Nodes on the list can vote on the transaction. The consensus process is as follows:
(1) Each verification node will continuously receive transactions sent from the network. After verification with the local ledger data, they are illegal. The transactions will be discarded directly, and the legal transactions will be summarized into a transaction candidate set (candidate set). The transaction candidate set also includes transactions left over from the previous consensus process that could not be confirmed.
(2) Each verification node sends its own transaction candidate set as a proposal to other verification nodes.
(3) After the verification node receives a proposal from other nodes, if it is not from a node on UNL, it will ignore the proposal; if it is from a node on UNL, it will compare it with the proposal. Transaction and local transaction candidate set, if there is the same transaction, the transaction gets one vote. Within a certain period of time, when a transaction receives more than 50% of the votes, the transaction enters the next round. Transactions that do not exceed 50% will be left for the next consensus process to be confirmed.
(4) The verification node sends transactions with more than 50% of the votes as proposals to other nodes, and at the same time increases the threshold of the required votes to 60%, repeating steps (3) and (4) until the threshold Reach 80%.
(5) The verification node formally writes the transactions confirmed by 80% UNL nodes into the local ledger data, which is called the last closed ledger, which is the last (latest) status of the ledger.
In Ripple's consensus algorithm, the identities of participating voting nodes are known in advance. Therefore, the algorithm is more efficient than anonymous consensus algorithms such as PoW. Transactions The confirmation time only takes a few seconds. This also determines that the consensus algorithm is only suitable for alliance chains or private chains. The Byzantine Fault Tolerance (BFT) capability of the Ripple consensus algorithm is (n-1)/5, which means it can tolerate Byzantine errors in 20% of the nodes in the entire network without affecting the correct consensus.
2. Simple diagram understanding mode
Schematic diagram of node interaction in the consensus process:
Consensus algorithm process:
(8) POOL verification pool consensus mechanism
The Pool verification pool consensus mechanism is a mechanism developed based on traditional distributed consensus algorithms (Paxos and Raft). The Paxos algorithm is a consensus algorithm based on message passing and highly fault-tolerant proposed in 1990. In the past, Paxos has been the standard for distributed protocols, but Paxos is difficult to understand and even more difficult to implement. Raft is a consensus algorithm released in 2013 that is simpler than Paxos and can realize the problems solved by Paxos. The process of reaching consensus in Paxos and Raft is like an election. Candidates need to convince the majority of voters (servers) to vote for them and follow their actions once selected. The difference between Paxos and Raft lies in the specific process of election. The Pool verification pool consensus mechanism is based on these two mature distributed consensus algorithms, supplemented by a data verification mechanism.
⑶ What is blockchain, what is consensus, and what is currency circle
Blockchain is based on distributed accounting and decentralization. Encrypted information transmission. Distributed accounting means the right to exist that cannot be destroyed, and decentralization means the right to independent transmission that cannot be tampered with. The two together are defined by Qingquan as "indestructible."
However, the blockchain has weak links, and it is heavily dependent on the network for its existence. Not just on a delivery level, but also on a recording level. The core layer of the blockchain is the physical layer, which is parasitic on the Internet system. If one day the Internet around the world is forcibly suspended, then the independent system of the blockchain will also fall into a state of suspended animation.
However, this kind of suspended animation is not real death, but requires some kind of systematic key to activate. Is there such a systematic key now? some.
Consensus comes from cognition.
Anyone with a little common sense in economics knows one thing clearly: legal currency is worthless! In fact, from the beginning of the forced decoupling of the British pound from the metal standard to the collapse of the Bretton Woods system, the legal currency of any country in the world is de facto valueless. The so-called purchasing power of legal currency is guaranteed by administrative coercion, but this administrative coercion is often abused. Therefore, the Guanjin volume we once saw in textbooks is returning to the world's economic tide, starting from the US dollar. QDI quantitative easing to the "appropriate easing" of China's monetary policy,The actual meaning is that the money printing machine will work overtime.
However, the money supply is subject to an offer from the total supply and demand of society. Within the scope of this offer, the face value of the currency is still guaranteed. Once it deviates from the For this offer, the currency needs a "reservoir". I once said that the concepts of the U.S. stock market and China's real estate market are the same in the economic sense. Of course, there are also those who dare not spend money.
Legal currency must be devalued. This concept involves more advanced economic knowledge, and even thirty chapters cannot be completed here. Depreciation within a certain range is beneficial to the development of human society, but this certain range is often abused. This comes from the weakness of legal currency itself - administrative coercion. But administrative coercion cannot defeat human nature.
Therefore, since the emergence of the blockchain, people with foresight have begun to try to defeat the depreciation of legal currency by assigning value to the blockchain. As a result, we have also seen that from that piece of pizza until now, we are still seeking to assign value to the blockchain.
Is this all the consensus is? no.
In the process of the development of blockchain technology, various algorithm differences have emerged, such as sharding, encryption, storage, running speed and network carriers, which are the coins we see now. This phenomenon is essentially a "split of consensus", but there is no way around it, because although BTC is the originator, it does not meet our needs for the blockchain in terms of value assignment. He is too slow, too old and too young to withstand the impact of legal currency. In the economic sense, BTC is now defined as a luxury product rather than a digital currency, because when studying the match between its value projection curve and the economic tide, it was found that it is surprisingly similar to luxury goods.
The currency circle is the bud formed by the mutual dissolution of blockchain development assignments and legal currency. In essence, the existence of the currency circle is the inevitable amplification of blockchain consensus. The currency circle is not the whole of the blockchain, it is just A flower for which we still expect fruit.
What is our ideal blockchain application?
When the utility of legal currency is unbalanced due to some kind of force majeure, we can use the independent system established by the blockchain for value exchange. But it is a pity that the utility of legal currency is not unbalanced, but this value exchange system has entered the economic cycle prematurely. The most notorious one is the dark web, and there is also the "money laundering" that haunts us all the time. This gives the currency The circle was shrouded in a layer of sadness.
It must be pointed out that even the above value exchange is not the value exchange defined by Qingquan.Instead, the consensus of the blockchain is used to serve as a medium for legal currency interoperability. The background of the blockchain is far from this.
The real blockchain should be a useful supplement and adjustment in the normal legal currency economic cycle system, and should also be a replacement when the normal legal currency economic cycle system fails. Although we don’t want to think about it that much, I really don’t want to see the situation of carrying a big bag of banknotes in exchange for two pounds of potatoes.
However, is the current currency circle ready for this? not yet! The current currency circle only believes in the four-year cycle but has abandoned the original appearance of the blockchain. Some people even use these coins, these technologies, and these consensuses as tools of deception and fraud. This is the tragedy of the entire human society!
Talking about trading, there have been countless cases of getting rich in the currency circle, so much so that it has given Leecai the illusion that "maybe that person will be me". Playing with spot products, I can't stand the loneliness and it is slow to make money, and playing with contracts is even more difficult. Needless to say, it is the same as gambling. Anyone who has been trading in this circle for huge profits has never seen anyone not losing money.
#BTC[超话]# #OUyiOKEx# #digital currency#
⑷ What is Guoxin Public Chain
China Information Chain (CIC) was undertaken by China Guoxin Information Corporation after the meeting on October 24, 2019, with the approval of the superior unit, in conjunction with international and domestic scientific research institutions, local people's governments and It is an important task for relevant institutions to jointly build.
CIC Guoxin Public Chain uses the national e-government extranet cloud as its infrastructure to build the world's first national sovereign public chain. Its purpose is to promote the digital economy, serve the real economy, and provide trusted computing for the “One Belt, One Road” initiative. The goal is to become the most credible national sovereign public chain in the world.
The China Information Corporation Blockchain Research Institute aims to promote the research, development, construction and key technology of the China Information Chain (CIC) with my country’s independent technical capabilities. For the purpose of operating services, it is based on the layout and development direction of the CIC Guoxin public chain industry, facing the major needs of my country's economic and social development in the new era, aiming at the international frontier, strengthening independent innovation, accelerating the transformation of results, and developing key technologies in Guoxin public chain key facilities and application platforms. Carry out work in , software systems and operational service support to serve major national strategies and economic and social development.
⑸ Blockchain Era: Transformation from Information Internet to Value Internet
Guosen’s Viewpoint
Guosen Overseas Group’s Viewpoint:
Internet Development Until now, its main function is to allow information to circulate on the Internet, and information is spread by copying (A is copied to B). Blockchain constructionThe "ledger" is open, transparent, non-tamperable, peer-to-peer interconnected, and easy to trace, and builds an infrastructure based on a trust mechanism to allow the value of digital assets to circulate efficiently on the Internet, and the value of digital assets to transfer on the Internet (from A is transferred to B, rather than copied from A to B). We are optimistic about the future of blockchain. However, the most important achievement of blockchain at this stage is the evangelism of ideas. Its emergence allows the market to see the shortcomings of the "Internet of Information" and the trend of the "Internet of Value".
Comments
The relationship between blockchain and Bitcoin
Explaining blockchain, there is no way around Bitcoin. The "invention" of Bitcoin has proven the feasibility of blockchain technology. Bitcoin is not the entirety of blockchain technology, but only one of its applications. Without Bitcoin, it’s possible that blockchain wouldn’t have happened, or at least not anytime soon.
The origin of the word "blockchain" is the "chain of blocks" in the original English version of the Bitcoin white paper. When translated into Chinese, the word "blockchain" is used. As the focus of Bitcoin mining shifts to China, the Chinese market has become the main battlefield for blockchain and Bitcoin. The English domestic market of blockchain is written as "blockchain", which has become a proper noun for the entire blockchain technology in the world. (Noun evolution path: chain of blocks - blockchain - blockchain).
The total amount of Bitcoin is limited, stimulating market speculation
Whether Bitcoin is regarded as a commodity or currency, due to its limited total amount, it stimulates market speculation on Bitcoin. Price, referred to as currency speculation. According to the Bitcoin generation mechanism, the total number of Bitcoins is 21 million.
Bitcoin is the reward after a new block is connected. A block is generated every 10 minutes. A certain number of Bitcoins are rewarded for each block generated. 50 are rewarded in the first four years. The number of Bitcoin rewards is halved every four years, so the total number of Bitcoins is 21 million. Calculation method: {50 X 6 X 24 X 365} X 4 X {1+1/2+. . . . . (1/2)n}=21 million (2.1*107).
Technical principles of blockchain
Blockchain timestamps all transactions through random hashing and merges them into an ever-extending random hash-based, working The proof-of-work chain is used as a transaction record. Unless all the proof-of-work is completed again, the transaction record cannot be changed. There are three steps to form a new block:
1. The miner packages the four parts of the "ledger, the header of the previous block, the timestamp, and the random number sequence X" within a period of time into a block;
2. Through a large number of calculations, the miner adjusts the random number sequence X of the block, generates the composite required hash value, and obtains Bitcoin rewards.
3. Miners combine the new block with the previous oneBlocks are connected together to form a new blockchain.
The number of patents is an important indicator for quantifying blockchain companies at this stage
The global blockchain industry is still in the early stages of development. Most companies are in the conceptual design stage and have no commercialized products. It is difficult for outsiders to objectively evaluate the pros and cons of startups. We believe that the number of blockchain invention patents can reflect the potential of each company and is an important indicator for distinguishing blockchain companies through quantitative means at this stage.
Investment advice: Based on the fundamentals of the company, focus on the value of the Internet in the blockchain era
With the development of the Internet to the present, its main function is to allow information to circulate on the Internet, and information can be copied. propagation method (A is copied to B). The "ledger" constructed by the blockchain is open, transparent, non-tamperable, peer-to-peer interconnected, and easy to trace, and builds an infrastructure based on a trust mechanism to allow the value of digital assets to circulate efficiently on the Internet, and digital assets occur on the Internet. Transfer of value (transfer from A to B, rather than copying from A to B). We are optimistic about the future of blockchain. However, the most important achievement of blockchain at this stage is the evangelism of ideas. Its emergence allows the market to see the shortcomings of the "Internet of Information" and the trend of the "Internet of Value".
Realizing the "Internet of Value" requires large-scale application implementation, not a single technology. At this stage, blockchain is still in its early stages of development. We are optimistic about the future of blockchain, but we do not overestimate the present of blockchain.
In the Hong Kong stock market, there are many companies involved in blockchain. Based on the company's fundamentals and the number of blockchain patents, we recommend Tencent Holdings and Launch Technology, maintaining performance forecasts and recommendation ratings.
Tencent (0700.HK): We expect the company’s revenue growth rate from 2019 to 2020 to be 22% and 22%, and net profit growth rate to 23% and 16%, of which NON-GAAP profit growth rate is 15%, 16%. The EPS corresponding to 2019 and 2020 are HK$10.4 and 12.1, and the target valuation range is maintained at 380 to 400 yuan, corresponding to 31 times to 33 times PE in 2020. The overweight rating is maintained.
Launch Technology (2488.HK): We predict that the company’s revenue growth rate from 2019 to 2020 will be 9.7% and 12.2%, and its net profit growth rate will be 69% and 29%, corresponding to EPS of 0.32, 0.42 Hong Kong dollars. We maintain a "buy rating" and recommend a reasonable valuation of HK$8-9, corresponding to 25-28 times PE in 2019.
Risk warning
1. Blockchain concepts cannot be turned into products. 2. The emergence of new technologies causes the blockchain to be falsified. 3. The profits from the company’s existing business cannot support the long-term R&D investment in blockchain.
Appendix: Blockchain-related companies in Hong Kong stocks
1. Tencent (0700.HK): has a dedicated blockchain portal (https://trustsql.qq), on October 19, 2019, Tencent released the "2019 Tencent Blockchain White Paper", which comprehensively introduced Tencent's blockchain solutions, including the TrustSQL blockchain underlying platform and Tencent Cloud TBaaS, and demonstrated in detail Four Tencent blockchain best practices include blockchain electronic invoices, micro-enterprise chain, Zhixin chain and blockchain bank draft. Tencent, which focuses on "connection", continues to develop infrastructure construction in the field of blockchain and promotes the implementation of "blockchain+" industry solutions to promote value connections between enterprises and between enterprises and consumers. Through the "blockchain+" model, we empower the financial and real industries, promote the integration of blockchain and industry, and accelerate the construction of industrial blockchain.
2. China Mobile (0941.HK): On October 15, 2019, the Blockchain Service Network (BSN) press conference and event was hosted by the Information Center, hosted by China Mobile Communications Group Corporation and China UnionPay Co., Ltd., and co-organized by Beijing Hongzao Technology Co., Ltd. The Technology Development Summit Forum was successfully held in Beijing. China Mobile utilizes existing resources, cloud facilities and computing storage facility resources to conduct independent research and development and optimize existing facilities; as a new cornerstone, China Mobile promotes the mutual empowerment between 5G and blockchain.
3. Ping An of China (2318.HK): The number of global blockchain invention patent applications disclosed in 2018 was 84, ranking 7th in the world. Ping An relies on blockchain technology to improve the intelligent level of urban management. Ping An applies blockchain to medical health, targeted poverty alleviation, social welfare, etc.
5. ZhongAn Online (6060.HK): Anlian Cloud, a professional ecological cloud service platform based on artificial intelligence, blockchain and cryptography. The platform uses Zhongan Chain independently developed by Zhongan as its underlying infrastructure and also develops electronic signing , digital identity, distributed encrypted storage, certificate storage, traceability and other nearly 10 vertical applications.
6. Kingsoft (3888.HK): It was the first to implement Game + Blockchain applications and solutions. Currently, the game cloud business is exploring the application of blockchain technology and accelerating the expansion of the game ecosystem. In the first half of 2018, Kingsoft Cloud took the lead in launching the "project-X" plan for the entire ecosystem of blockchain games, realizing a project consisting of blockchain platform infrastructure construction, blockchain underlying technology, and blockchain game development, operation, and distribution. Complete blockchain game ecological structure.
7. HC Group (2280.HK): On January 31, 2018, HC Group announced that its first application scenario based on blockchain was officially launched. The cooperation framework agreement signed with Joyvio Technology will start from the agricultural field to build the HC Group District. Blockchain products use the advantages of industrial big data and blockchain application scenarios to expand the modern agricultural blockchain market.
8. Launch Technology (2488.HK): The company is China's earliest high-tech company dedicated to the research and development and production of automotive diagnosis, testing, maintenance, and tire equipment.New technology leading enterprise. As a leader in the Internet of Vehicles industry, the company is deeply involved in exploring solutions for the integration and monetization of automotive big data. In 2018, the company ranked fifth in the world in terms of the number of blockchain-related patent applications, standing at the forefront of new blockchain technologies. The company has combined blockchain technology with industry applications and developed the "Super Chain Project" series product, a 4G vehicle data collection terminal with blockchain technology – GTBOX-I, tailored for the Internet of Vehicles industry. Launch Technology has publicly stated its position many times: No matter whether it is declining or rising, it refuses to get involved in digital currencies and ICOs. It neither public nor private placements, and concentrates on exploring the value of the chain.
9. Meitu Company (1357.HK): The vision of Meitu Blockchain is to connect the digital world and reality by creating a decentralized, secure and encrypted identity pass for users: Meitu Intelligent Passport (MIP - Meitu Intelligent Passport) world and create a trusted blockchain environment. On the one hand, Meitu Intelligent Pass (MIP) allows users to anchor assets scattered across various applications on the blockchain, and through face recognition AI verification, use various applications more conveniently and securely, and receive privacy protection; On the other hand, Meitu Intelligent Pass (MIP) also allows some services that require strong verification, such as the medical and education fields, to more effectively use blockchain to serve users.
10. Gome Retail (0493.HK): On April 14, 2018, according to Gome Retail, Gome has entered the era of comprehensive digitalization. Operating digital stores is Gome’s “No. 1 Project”, and the company’s focus on blockchain technology and decentralization Technology is always doing research. The relevant person in charge of Gome Retail said: Gome’s shared retail business model and employee beauty store retail strategy are very consistent with the decentralized model system of the blockchain. The employee beauty store is also a new channel that Gome hopes to build.
(Source of article: Guosen Securities)
Solemn statement: The purpose of releasing this information is to spread more information and has nothing to do with the position of this site.⑹ Consensus mechanism of blockchain
1. How to confirm and reach consensus on transaction information on the network?
Although the consensus mechanism is often mentioned, the meaning and understanding of the consensus mechanism are not clear. Therefore, it is necessary to understand the relevant concepts, principles and implementation methods of the consensus mechanism.
The transaction information of the blockchain is transmitted to each node in the network through network broadcast. How to confirm the broadcast information and reach a consensus among the entire network nodes and finally write it into the block? If there is no corresponding reliable and secure implementation mechanism, it will be difficult to realize its basic functions. Therefore, the consensus mechanism is a key to the operation of the entire network.
The consensus mechanism solves the problem of how the blockchain achieves consistency in a distributed scenario. The blockchain can reach a relatively balanced state among many nodes because of the consensus mechanism. So how does the consensus mechanism solve the problem of mutual trust between nodes based on the idea of decentralization?
When the idea of distribution was proposed, people began to design consensus algorithms based on the FLP theorem and the CAP theorem. Standardly speaking, the consistency of an ideal distributed system should meet the following three points:
1. Termination: The consistency result can be completed within a limited time.
2. Consensus: The final decision-making results of different nodes should be the same.
3. Validity: The result of the decision must be a proposal put forward by other processes.
However, in actual computer clusters, the following problems may exist:
1. Nodes have different transaction processing capabilities, and the data throughput of network nodes is different
2. The communication channel between nodes may be unsafe
3. There may be malicious nodes
4. When asynchronous processing capabilities reach a high degree of consistency, The scalability of the system will become worse (cannot tolerate the addition of new nodes).
Scientists believe that it is impossible to achieve complete consistency in a distributed scenario. However, engineers can sacrifice part of the cost in exchange for the consistency of distributed scenarios. The above two major theorems also have this idea. Therefore, various formula mechanisms based on blockchain design can be regarded as sacrificing part of the cost in exchange for more adaptability. My idea is to make a flexible transformation on this idea, that is, sacrificing part of the cost at the appropriate time and space in exchange for consistency adapted to the scene at that time, and a flexible blockchain system can be realized that is pluggable. Pull-out blockchain system. Today I will introduce my views and analysis on various consensus mechanisms. Distributed systems with or without malicious nodes are divided into Byzantine fault-tolerant and non-Byzantine fault-tolerant mechanisms.
The FLP theorem is the impossibility of FLP. It proves that in a distributed scenario, no matter any algorithm, even if only one process hangs up, there is an inability to reach consensus for other non-failed processes. possible.
FLP is based on the following assumptions:
Can only be modified once: Each process initially records a value (0 or 1). The process can receive messages, change the value, and send messages. When the process enters the decide state, the value will no longer change. All non-failed processes enter decided state, the protocol ends successfully. This is relaxed to the extent that some processes enter the decided state, even if the agreement is successful.
Asynchronous communication: The biggest difference from synchronous communication is that there is no clock, no time synchronization, no timeout, no detection failure, messages can be delayed arbitrarily, and messages can be out of order.
Communication is robust: As long as the process does not fail, the message will be delayed indefinitely, but will eventually be delivered; and the message will only be delivered once (no duplication).
Fail-Stop model: A process failure is like a downtime and no more messages are processed.
Number of failed processes: At most one process fails.
CAP is the most discussed theory in distributed systems, especially in the field of distributed storage. CAP was proposed by Eric Brewer at the PODC meeting in 2000. It was a result of Eric Brewer's research on data consistency (consistency), service availability (availability), and partition fault tolerance (partition- tolerance) conjecture:
Data consistency (consistency): If the system returns success for a write operation, then subsequent read requests must read the new data; if the system returns failure, then all read operations No one can read this data. For the caller, the data has strong consistency (also called atomic and linearizable consistency) [5]
Service availability (availability) : All read and write requests are responded to within a certain period of time, can be terminated, and will not wait forever
Partition-tolerance: In the case of network partitions, the separated nodes can still function normally External services
If AP is satisfied at a certain moment, the separated nodes can provide external services at the same time but cannot communicate with each other, which will lead to inconsistent status, that is, C cannot be satisfied; if CP is satisfied, C will not be achieved in the case of network partitions , the request can only wait forever, that is, A is not satisfied; if CA is to be satisfied, the node status must be consistent within a certain period of time, and network partitions cannot occur, so P cannot be satisfied.
C, A, and P can only satisfy at most two of them. Like the FLP theorem, the CAP theorem also indicates an unreachable result (impossibility result).
⑺ How to understand the consensus mechanism in the blockchain
The so-called consensus simply means that everyone has reached an agreement.
In the blockchain, it is actually a rule. Each node confirms its own data according to this rule, and finally maintains the consistency of the database of the entire network.
If we take an example from life, for example, the company held a meeting today, but since the boss is not here, everyone needs to discuss and decide whether to do a project.
In such a leaderless environment?
