Pbft mining

1. Go is an open source programming language, which makes it easy to construct simple, reliable and efficient software. If you want to learn this programming language, you should first find a good tutorial. Brother Lian's go language + blockchain training has recently published a new set of go language tutorial, and the teacher's speaking is very good

with the global hot discussion of the concept of "blockchain", the application of blockchain technology has been quietly added to the daily life scenes such as finance, logistics, credit reference, manufacturing and retail. Some experts have shown that the future blockchain will be closely related to people's lives, and the integration of blockchain technology and people's daily life is the general trend

the popularity of the blockchain market has triggered a large number of talents demand based on blockchain technical personnel, and the popularity of blockchain talents is rising at the speed of light. According to the "2018 blockchain high salary list" released by lagou.com, Tencent, Xiaomi, Suning, Jingdong and other domestic enterprise giants have released many high salary blockchain post demands, trying to explore blockchain related technologies and applications. It is also pointed out in the list that the demand for high salary jobs is mainly based on blockchain related technical jobs, among which Suning and Keda have been given the highest monthly salary of 100k

the huge market demand for technical talents will inevitably lead to the explosive emergence and growth of the whole blockchain training market. Most of the training modes can be divided into online training, traditional IT organization training, and offline short-term training camps, which mainly focus on high-end forms. However, in the process of the hot market evolution, there are also a variety of blockchain training chaos: lecturers' qualifications are watered down, and even the most basic names are not disclosed, the syllabus is opaque, and the teaching quality is shrinking, Unreasonable class arrangement and uneven training fees and so on

with the large-scale development of the whole blockchain training market, brother company ecation, together with Yin Cheng, a senior blockchain expert, and his Tsinghua Shuimu Weiming team, has set up a blockchain college. With its professional and powerful team of technical lecturers, detailed and comprehensive curriculum system, and a large number of authentic enterprise blockchain projects, it aims to deepen the blockchain teaching and training field, And train more professional technical talents for enterprises and society<

Yin Cheng, a senior blockchain technology expert, graated from Tsinghua University, is the dean of brother Lian blockchain college. He once served as Google Algorithm Engineer, the world's most valuable expert in the field of Microsoft blockchain, and the gold medal lecturer of Microsoft tech.ed conference. Proficient in C / C + +, python, go language, sicikit learn and tensorflow. With 15 years of programming experience and 5 years of teaching experience, senior software architect, Intel Software Technology expert, famous technology expert, with many years of working experience in the world's top it company Microsoft Google. He has many years of experience in software programming and lecturing, and has developed many procts in human-computer interaction, ecation, information security, advertising and blockchain system. He has deep experience in project management and R & D, has two AI invention patents, and has practical experience in developing e-money deployed to Microsoft Windows azure. Teaching explanation is in simple language, so that students can apply what they have learned
the first stage: blockchain instry and go programming for 5 weeks
the second stage: cryptography and consensus algorithm for 2 weeks
the third stage: Ethereum source code analysis and development for 3 weeks
the fourth stage: Super ledger and node.js for 2 weeks
the fifth stage: bitcoin & EOS for 4 weeks
the sixth stage: comprehensive actual combat of the project

2. Triporg travel: a travel service application using the underlying technology of blockchain, which can provide travel prepaid services such as train tickets and air tickets.

3.

At present, whether a digital currency is a valuable currency basically belongs to the "angel wheel" stage. There are three criteria to determine whether a digital currency is a valuable currency: one is the team, the other is the economic model, and the third is the instry demand

The randomness of the

team is too great, so we will not discuss it here. This paper first makes a detailed analysis of the economic model of digital currency. In the following article, the author will analyze some digital currencies according to different instries

Strictly speaking, the economic model involved in this paper is not completely equivalent to the concept described in economics. Especially in digital currency, currency consensus mechanism and incentive mechanism

Consensus mechanism is the strategy and method for each node in the blockchain system to reach an agreement, which should be selected flexibly according to the different types of system and application scenarios

common consensus mechanisms include pow, POS, dpos, pbft (and its variants), etc. In addition, based on the different application scenarios of blockchain technology and the characteristics of various consensus mechanisms, this paper evaluates the technical level of various consensus mechanisms according to the following dimensions:

A) compliance supervision: whether super permission nodes are supported to supervise the nodes and data of the whole network

b) performance efficiency: the efficiency of reaching a consensus and being confirmed

Resource consumption: CPU, network input and output, storage and other computer resources consumed in the process of consensus

d) fault tolerance: the ability to prevent attacks and fraud

1 instry background

looking for Instry pain points: asset management needs professional team and knowledge, but now most digital currency investors do not have it; The fluctuation of digital money market is huge, and investors can't keep the value of assets in the falling market

2 own advantages

in the stock and futures markets for many years, has a mature and high-quality asset management team; AI big data team has strong technical strength

3 Market Research

after market research, it is estimated that the market value of asset management will be about US $1 billion in the next five years

4 total amount of digital currency

after considering the expected asset management market value, development cycle and difficulty, we will consider issuing 2 billion pieces of XT based on Ethereum erc20 digital currency, and never issue additional ones

5 allocation method

early stage investors hold 10%, teams hold 20%, business operation 10%, community construction 10%, and investors hold 50%

6 digital currency release / repo mechanism

the release mechanism can be divided into three categories:

the first category: the money holding part of business operation is fully unlocked, and the purpose is limited to business and operation activities

the second type: the release mechanism of community construction is that community members release exclusive information, cooperation platform release exclusive project progress and so on. According to the number of participating IDS, the corresponding proportion of XT is released (publishers and participants get 50% each) until all the releases are completed (after the release, the follow-up reward comes from the platform profit pool)

the third category: investors hold the mainstream digital currency, conct asset management in the platform, release a certain amount of XT according to the exchange ratio, and the early investors and the team hold part of it synchronously and unlock it according to the proportion

the repo mechanism is: 50% of the profit (in XT) will be returned to the holder; The rest goes into the platform profit pool, and 50% of XT in the profit pool is destroyed monthly until the total number of XT is 1 billion; The rest will be used as platform ecological construction fund

7 digital currency equity

profit sharing: holding XT is for platform users, and they can enjoy 50% of platform profits

platform Governance: participating in platform activities, enjoying XT awards and airdrop activities of other project parties

function customization: Based on platform AI big data, investors can purchase services optimized for indivial trading strategies

4. Blockchain is a technology, but it is not a single technology, but the result of the integration of a variety of technologies, including cryptography, mathematics, economics, network science and so on. You can think of it as a distributed shared accounting technology, or as a database, but the database is jointly maintained by all nodes in the chain, and each node has an account book. Because the account books of all nodes are consistent, different nodes can trust each other, and there is no doubt about the data, so we all say that the blockchain has realized trust technically. For detailed professional technology, you can consult some professional technology companies, such as Jinbo technology, which focuses on the development of blockchain related procts, professional R & D team and perfect after-sales service, and you can consult by telephone.

5. It's a very good coin. It's recommended to get it at least at the end of the year.

6. < UL >

advantage: unlimited currency needs three confirmations for a transaction, and each confirmation takes 30 seconds, so the transaction confirmation speed is very fast. It is used in daily and common transactions, which is more practical

7. Non ferrous stocks in the performance of small cap stocks: mainly Baotou Steel Rare Earth, Yunnan copper, Shandong gold, Zhongjin gold, Tongling Nonferrous and so on

small cap stocks refer to the relative and large cap stocks. Large cap stocks: usually refer to the stocks of listed companies with a large number of outstanding shares. On the contrary, small cap stocks are the stocks of listed companies with a small amount of circulating stocks. At present, in China, the circulating stocks of no more than 100 million stocks can be regarded as small cap stocks<

nonferrous metals is the abbreviation of nonferrous metals, nonferrous resources is related to nonferrous metals mining, smelting and other instries of listed companies
typical Baotou Steel Rare Earth, Zhongjin gold, Tongling Nonferrous Metals, Yunnan Copper and many other, specific can enter the market software plate, check the "nonferrous metals" plate, in which more than 60 stocks are very detailed. There is also the concept of mineral resources, which reflects the main business transformation of some listed companies involving mineral resources.

8. First of all, no consensus mechanism is perfect. Each consensus mechanism has its own advantages and disadvantages. Some consensus mechanisms are created to solve some specific problems
1. Pow (proof of work) workload proof
in a word: the more you do, the more you get
it relies on machines to perform mathematical operations to obtain accounting rights. Compared with other consensus mechanisms, the resource consumption is high and the supervision is weak. At the same time, the whole network needs to participate in the operation to reach a consensus every time, so the performance efficiency is relatively low. In terms of fault tolerance, 50% of nodes in the whole network are allowed to make mistakes< Advantages:
1) the algorithm is simple and easy to implement
2) there is no need to exchange additional information between nodes to reach a consensus
3) the cost of destroying the system is huge< Disadvantages:
1) waste of energy
2) it is difficult to shorten the block confirmation time
3) the new blockchain must find a different hash algorithm, otherwise it will face bitcoin attack
4) it is easy to generate bifurcation and needs to wait for multiple confirmations
5) there is no finality, and checkpoint mechanism is needed to make up for it
2. POS proof of stake
in a word: the more you hold, the more you get
the main idea is that the difficulty of obtaining the node's accounting right is inversely proportional to the equity held by the node. Compared with pow, the resource consumption brought by mathematical operation is reced to a certain extent, and the performance has also been improved correspondingly. However, it is still a way to obtain the accounting right based on hash operation competition, which is weak in supervision. The fault tolerance of the consensus mechanism is the same as pow. It is an upgrade consensus mechanism of pow, according to the proportion and time of token of each node, it can rece the difficulty of mining in equal proportion, so as to speed up the speed of finding random numbers
advantages: to a certain extent, it can shorten the time of reaching consensus; No longer need to consume a lot of energy mining
disadvantages: mining is still needed, which does not solve the pain point of commercial application in essence; All the confirmations are just a probability expression, not a certainty. Theoretically, there may be other attack effects. For example, Ethereum's Dao attack event caused Ethereum's hard fork, and etc's appearance of this event actually proved the failure of this hard fork
the principle of dpos is the same as that of POS, except that some "deputies to the National People's Congress" are selected
bitshares community first proposed dpos mechanism
the main difference from POS is that the node elects several agents, which are verified and recorded by the agents. Its compliance, performance, resource consumption and fault tolerance are similar to POS. Similar to board voting, coin holders cast a certain number of nodes to verify and account on their behalf
the working principle of dpos is:
decentralization means that each shareholder has influence according to its shareholding ratio, and the voting result of 51% shareholders will be irreversible and binding. The challenge is to achieve 51% approval in a timely and efficient way. To achieve this goal, each shareholder can delegate his voting right to a representative. The top 100 representatives with the largest number of votes will take turns to proce blocks according to the established schele. Each delegate is assigned a time period to proce the block. All representatives will receive 10% of the transaction fee equivalent to an average block. If an average block contains 100 shares as a transaction fee, a representative will receive 1 share as a reward
network delay may make some representatives fail to broadcast their blocks in time, which will lead to the bifurcation of the blockchain. However, this is unlikely to happen because the representative of the manufacturing block can establish a direct connection with the representative of the block before and after manufacturing. This direct connection to your next representative (and perhaps the next) is to make sure you get paid
this mode can generate a new block every 30 seconds, and under normal network conditions, the possibility of blockchain bifurcation is extremely small, even if it occurs, it can be solved in a few minutes
to be a delegate:
to be a delegate, you must register your public key on the network and assign it to a 32-bit unique identifier. The identifier is then referenced by the "header" of each transaction data
authorized ballot:
each wallet has a parameter setting window, in which users can select one or more representatives and grade them. Once set, each transaction made by the user will transfer the vote from "input representative" to "output representative". In general, users will not create transactions specifically for voting purposes, because that will cost them a transaction fee. But in an emergency, some users may find it worthwhile to change their vote in a more positive way by paying fees
keep representatives honest:
each wallet will display a status indicator to let users know how their representatives are doing. If they miss too many blocks, the system will recommend users to replace them with a new representative. If any representative is found to have issued an invalid block, all standard wallets will ask for a new representative to be selected before each wallet makes more transactions
resist attack:
in resisting attack, because the top 100 representatives have the same power, and each representative has an equal vote. As a result, power cannot be concentrated on a single representative by winning more than 1% of the vote. Since there are only 100 representatives, we can imagine an attacker carrying out a denial of service attack on each representative in turn. Fortunately, the threat of this particular attack can be easily mitigated by the fact that each delegate's identity is his public key rather than his IP address. This will make it more difficult to target DDoS attacks. The potential direct connection between representatives will make it more difficult to block their proction
advantages: the number of nodes participating in verification and bookkeeping is greatly reced, which can achieve second level consensus verification
disadvantages: the whole consensus mechanism still relies on token, and many commercial applications do not need token< Pbft: practical Byzantine fault tolerance
3. Pbft: practical Byzantine fault tolerance
Introction: it provides (n-1) / 3 fault tolerance on the premise of ensuring the activity and safety
in distributed computing, different computers try to reach a consensus through message exchange; But sometimes, the coordinator / commander or member / client may exchange wrong messages e to system errors, which may affect the final system consistency
the Byzantine general problem is based on the number of wrong computers to find possible solutions, which can not find an absolute answer, but can only be used to verify the effectiveness of a mechanism
the possible solutions to Byzantine problems are:
consistency is possible when n ≥ 3F + 1. Where n is the total number of computers and F is the total number of computers with problems. After the information is exchanged among computers, each computer lists all the information obtained and takes most of the results as the solution
1) the operation of the system can be separated from the existence of currency, pbft algorithm consensus that each node is composed of business participants or regulators, and the security and stability are guaranteed by business stakeholders
2) the consensus delay is about 2-5 seconds, which basically meets the requirements of commercial real-time processing
3) consensus efficiency is high, which can meet the demand of high frequency trading volume
disadvantages:
1) when 1 / 3 or more bookkeepers stop working, the system will not be able to provide services
2) when 1 / 3 or more bookkeepers work together, and all other bookkeepers are just divided into two network islands, malicious bookkeepers can make the system bifurcate, but will leave cryptographic evidence
let's talk about two domestic ones ~
4. Dbft: delegated BFT authorization Byzantine fault tolerance algorithm
Introction: dbft mechanism adopted by ant, The bookkeeper is selected by the rights and interests, and then the bookkeeper reaches a consensus through Byzantine fault-tolerant algorithm
based on pbft, this algorithm has the following improvements:
the request response mode of C / S architecture is improved to a peer-to-peer mode suitable for P2P network
the static consensus participation node is improved to a dynamic consensus participation node that can enter and exit dynamically
for the generation of consensus participation nodes, a voting mechanism based on the proportion of holding equity is designed, and the consensus participation nodes (Accounting nodes) are determined by voting
digital certificate is introced into the blockchain to solve the authentication problem of the real identity of the accounting node in voting< Advantages:
1) professional bookkeeper
2) it can tolerate any kind of errors
3) bookkeeping is completed by multiple people, and each block is final and will not be forked
4) the reliability of the algorithm has strict mathematical proof
disadvantages:
1) when 1 / 3 or more bookkeepers stop working, the system will not be able to provide services
2) when 1 / 3 or more bookkeepers commit crimes together and all other bookkeepers are divided into two network islands, malicious bookkeepers can make the system bifurcate, but leave behind cryptographic evidence
to sum up, the core of dbft mechanism is to ensure the system's finality to the maximum extent, so that the blockchain can be applied to real financial application scenarios
5. Pool verification pool
is based on traditional distributed consistency technology and data verification mechanism
advantages: it can work without token, and realizes second level consensus verification on the basis of mature distributed consistency algorithms (pasox and raft)
disadvantages: the degree of decentralization is not as good as that of bictin; It is more suitable for multi center business model.