车联网区块链共识是什么,车联网区块链共识研究

❶ 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.

❷ What is blockchain and its application in the automotive field

1. The decentralization, transparency and trust of blockchain technology are to solve the current problems in the automotive industry Problems such as leakage of user privacy, poor dispersion of maintenance services, and irregularities have brought opportunities. The key to the application of blockchain in the automotive field lies in the construction and integration of car identity and user credit systems to create car logos, completely record key information during the manufacturing and use of cars, promote the standardization of the traditional automotive industry chain, and establish a reliable system for car companies. The service platform quality control system and optimized inventory dynamic management provide users with better repair, maintenance and second-hand car trading services. Combining car identity and personal credit, it is connected to the blockchain system and can transform the original car sharing business process. In the future, blockchain, as the underlying technology, will be combined with edge technologies such as the Internet of Things and big data to achieve safe interconnection of different smart devices, continuously improve the processing capabilities of blockchain technology, and accelerate its development in the fields of autonomous driving and intelligence. application.

3. Blockchain system information transparency, tamper-proof, and forgery can effectively solve this problem, which will have an impact on the financial Internet of Things, supply chain, government services and other fields. deep influence. Due to its transparent, reliable and traceable characteristics, blockchain technology can build a car identity and completely record the source of car parts and production processes, sales channels, use and maintenance, vehicle positioning and other data to promote into the traditional automotive industry chain. "Production, supply and marketing after market" standards. At the same time, a tamper-proof and securely encrypted user credit system can be built through the blockchain to record, store, and integrate user online transaction information and credit evaluations such as asset information, user information, and user behavior. Because the application of car retail, leasing, sharing and other scenarios is essentially an extension of the personal credit system, the blockchain system will eventually bring information such as identity, user credit and service history to owners through the blockchain system, which will be associated with car identities to improve the security of interconnection. to realize the application of blockchain autonomous driving in fields such as Internet of Vehicles and vehicle sharing.

❸ What is the consensus mechanism in blockchain technology

1. What is the consensus mechanism
In a decentralized structural system, due to the The status is equal. When disagreements arise, how to reach consensus becomes a problem.
So, a well-designed,A consensus mechanism that is simple to operate in practice is the key to the smooth operation of a distributed system.
In short, the consensus mechanism is an algorithm that reaches consensus on the order of things within a period of time. It is a mechanism for blockchain nodes to reach a consensus across the entire network on block information.

❹ What is blockchain consensus

In Bitcoin and other blockchain coins, there is also the problem of how to reach consensus. In other words, the core issue of Bitcoin or other blockchain coins is how to reach consensus in a decentralized environment.

Blockchain is the core technology behind Bitcoin and the infrastructure that supports Bitcoin. Therefore, when talking about blockchain consensus, we must talk about Bitcoin consensus.

The core breakthrough of Bitcoin is to reach a consensus on transaction events in a decentralized manner, that is, to reach a consensus on the validity of a transaction without a central organization.

Bitcoin’s method of achieving this consensus mainly includes two parts:

Incentive; that is, motivating participants by generating a certain amount of new Bitcoins in each block;< br />Introducing external resources to ensure security; that is, ensuring the security of the consensus through a large amount of external calculations, that is, Proof of Power;

This is also used by almost all PoW currencies method. For example, DECENT, Litecoin, SandCoin, Dogecoin, and more.

❺ What is the consensus mechanism known as the "soul of the blockchain"?

We know that the blockchain is a decentralized distributed accounting technology. In the blockchain system, Without a centralized accounting institution like a bank, how to ensure the consistency of each transaction on all accounting nodes? The consensus mechanism solves this problem, so it can also be said that the consensus mechanism is the soul of the blockchain.

Currently, the more common consensus mechanisms include: PoW (Proof of Work), Proof of Stake and Delegated Proof of Stake:

01

PoW (Proof-of-Work)

Proof of Work Mechanism

The full name of POW is Proof of Work, which means “Proof of Work” or “Proof of Work”. How much currency reward you get from mining depends on the mining contributionWorking efficiently, that is to say, the better the performance of the mining machine and the longer the mining time, the more monetary rewards will be obtained.

BTC is the most successful cryptocurrency under the POW mechanism. Although the POW mechanism has successfully proven its long-term stability and relative fairness, under the existing framework, the use of POW's "mining" form will consume a large amount 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.

02

PoS (Proof-of-Stake)

Proof of Stake Mechanism

POS is Proof of Stake or Equity Proof, the full name is Proof of Stake. The proof-of-stake model is a model that issues interest based on the amount and time of the currency held.

POS mechanism, compared to POW, POS mechanism saves energy and introduces the concept of "coin age" 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 the holder can sign and produce the next block. Once it signs the next block, the "coin age" held by the currency holder will be cleared and a new cycle will be re-entered.

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, as many as possible to clear his "coin days". 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 the "coin age") is much lower than the speed of network propagation and broadcasting, so in PUnder the oS mechanism, it is necessary to "limit the speed" of generated blocks to ensure the stable operation of the main network.

03

DPoS

Delegated Proof of Stake Mechanism

DPOS is delegated proof of stake.

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.

04 Other consensus mechanisms

There are other consensus mechanisms in the blockchain system, such as PBFT commonly used in alliance chains, POI used in New Economic Coin (NEM), etc. These consensus mechanisms are proposed to solve some shortcomings of existing consensus mechanisms. But there are not as many systems currently in use as POW, POS and DPOS.

The consensus mechanism is the core of the blockchain system, which determines the degree of decentralization, performance and security of a blockchain system. Therefore, in the development of public chains, the design of the consensus mechanism is the core and key.

❻ How to understand the consensus mechanism in the blockchain

The so-called consensus, simply understood, 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?

❼ What is blockchain consensus

The so-called "consensus mechanism" is to complete transactions in a very short time through the voting of special nodes Verification and confirmation; for a transaction, if several nodes with unrelated interests can reach a consensus, we can think that the entire network can also reach a consensus on it. To put it more simply, if a Chinese Weibo V, a virtual currency player in the United States, an African student and a European traveler interact with each other,We don't know each other, but they all agree that you are a good person, so it can basically be concluded that you are not a bad person.
Blockchain, as a data structure that stores data in chronological order, can support different consensus mechanisms. The consensus mechanism is an important component of blockchain technology. The goal of the blockchain consensus mechanism is to enable all honest nodes to save a consistent view of the blockchain while satisfying two properties:
1) Consistency. The prefix part of the blockchain saved by all honest nodes is exactly the same.
2) Effectiveness. Information published by an honest node will eventually be recorded in its own blockchain by all other honest nodes.

❽ Consensus mechanism of blockchain

The so-called "consensus mechanism" is to complete the verification and confirmation of transactions in a very short time through the voting of special nodes; For a transaction, if several nodes with unrelated interests can reach a consensus, we can think that the entire network can also reach a consensus on it. Beijing Muqi Mobile Technology Co., Ltd., a professional blockchain outsourcing development company, welcomes discussions for cooperation. Below we will look at several consensus mechanisms of blockchain, hoping to help everyone understand the basic technology of blockchain.

Due to the development of blockchain technology, everyone is no longer unfamiliar with the term consensus mechanism. With the development of technology, various innovative consensus mechanisms are also developing.

POW proof of work

Bitcoin uses the PoW proof of work mechanism, and later Ethereum used the PoW consensus mechanism. Pow is equivalent to calculating a difficult mathematical problem, which is to calculate the hash value of a new block, and the difficulty of the calculation will be adjusted every period of time. Although PoW is a consensus mechanism that is relatively recognized by everyone, calculations will consume a lot of energy and may pollute the environment.

POS Equity Proof

The probability of obtaining accounting rights is determined by the number and duration of holding Tokens. Compared with POW, POS avoids a large amount of resource waste caused by mining and shortens the time for each node to reach consensus. If the network environment is good, it can be achieved in milliseconds and has low requirements on node performance.

However, the shortcomings of POS are also obvious. Nodes holding more Tokens have a greater chance of obtaining accounting rights. This will lead to the "Matthew Effect", where the rich will get richer, destroying the decentralization of the blockchain. Centralization.

DPOS Proof of Equity

The principle of DPOS Delegated Proof of Equity is the same as that of POS. The main difference is that DPOS Token holders can vote to elect agents as super nodes, responsible for Produce blocks and maintain consensus rules on the network. If these nodes fail to perform their duties, new nodes will be voted in. The same disadvantage also tends to be centralized.

POA authority certificate

There is no need for communication between POA nodes to reach consensus, so it is extremely efficient. And it can also resist computing power attacks very well and has high security. But POA requires a centralized authoritative node to verify identity, which means it will harm the decentralization of the blockchain, which is also a compromise between decentralization and improved efficiency.

❾ What role can the popular blockchain technology play in the automotive industry?

Blockchain technology plays an important role in the development of the automotive industry, such as: in the automotive industry The formation of ecological alliances in the supply chain, applications in the second-hand car market, applications in automotive safety, etc.

1. Automotive industry supply chain financial alliance ecology based on blockchain technology

The integrated supply chain information platform based on blockchain technology connects enterprises in the automotive supply network with alliance chains Through the SDPOs consensus mechanism, a chain information system is established to establish a multi-center efficient supply system. Auto parts sources, production processes, sales channel tracking, maintenance records and other important information are all recorded in this chain. The information generated in the automobile manufacturing process will automatically trigger the corresponding smart contract, realize the automatic recording of the transaction information of upstream and downstream enterprises in the power supply chain, and automatically transfer the payment, and ultimately form a system with the automobile product information flow as the main body, the business flow and the logistics flow as the flow and The information structure supported by capital flow enables efficient and accurate storage and traceability of product information.

❿ 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 can achieve 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. The protocol ends successfully when all non-failed processes enter the decided state. 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).