Blockchain deletion

blockchain includes public blockchain, joint (instry) blockchain and private blockchain. Public chain point-to-point e-cash system: bitcoin, smart contract and decentralized application platform: Ethereum

blockchain is a new application mode of distributed data storage, point-to-point transmission, consensus mechanism, encryption algorithm and other computer technologies

blockchain is an important concept of bitcoin. In essence, it is a decentralized database. At the same time, as the underlying technology of bitcoin, it is a series of data blocks generated by using cryptographic methods. Each data block contains a batch of bitcoin network transaction information, Used to verify the validity of its information (anti-counterfeiting) and generate the next block

extended data

according to the different degree of blockchain network centralization, three kinds of blockchains under different application scenarios are differentiated:

1. The blockchain with the whole network open and without user authorization mechanism is called public chain

2. The authorized nodes are allowed to join the network, and the information can be viewed according to the authority. It is often used in the inter agency blockchain, which is called alliance chain or instry chain

3. All the nodes in the network are in the hands of one organization, which is called private chain

alliance chain and private chain are also called licensing chain, and public chain is called non licensing chain

blockchain features

1, decentralization. Blockchain technology does not rely on additional third-party management institutions or hardware facilities, and there is no central control. In addition to the self-contained blockchain itself, each node realizes information self verification, transmission and management through distributed accounting and storage. Decentralization is the most prominent and essential feature of blockchain

2. Openness. Blockchain technology is based on open source. In addition to the private information of all parties involved in the transaction is encrypted, the data of blockchain is open to everyone. Anyone can query blockchain data and develop related applications through the open interface, so the information of the whole system is highly transparent

3. Independence. Based on consensus specifications and Protocols (similar to various mathematical algorithms such as hash algorithm used by bitcoin), the whole blockchain system does not rely on other third parties, and all nodes can automatically and safely verify and exchange data in the system without any human intervention

4. Safety. As long as 51% of all data nodes cannot be controlled, the network data cannot be arbitrarily manipulated and modified, which makes the blockchain itself relatively safe and avoids subjective and artificial data changes

5. Anonymity. Unless there are legal requirements, technically speaking, the identity information of each block node does not need to be disclosed or verified, and the information can be transferred anonymously

Blockchain is on fire! It's so hot that I have no friends! In recent days, it has been swished by various popular science jokes of blockchain, just like crowdfunding, equity and original stocks in the past two years. If you go out and chat with others, you will be embarrassed to chat with others if you don't talk about blockchain. Textbook like explanation: an intelligent peer-to-peer network that uses distributed database to identify, disseminate and record information. It is a distributed database system with different nodes and an open ledger

the concept of "after the rules are settled, everyone will register spontaneously" in wechat organization corresponds to the concept of "decentralization, no single user can control it" in the blockchain. "Registration in wechat group" in wechat group corresponds to the concept of "peer-to-peer network" in blockchain. "As long as the network is connected, we can know the latest progress" in wechat organization Bureau, corresponding to the concept in blockchain, namely "game mechanism"

Blockchain is a new technology, not a disguised form of MLM. It is just claimed by many MLM organizations as "blockchain". In fact, there is no technology. It's just a practice of MLM under the name of "blockchain". The state has issued several announcements to crack down on this kind of MLM. The following is the Xinhua news report on MLM of blockchain:

blockchain is not equal to virtual currency, but also has security risks. Behind the popularity, there is exaggeration with "ulterior motives". Only by removing the flashiness, can the blockchain return to its real application value

invest 80000 yuan, change to 800000 yuan after three months? Shenzhen police cracked a huge fund-raising fraud. Under the guise of blockchain concept and 10 times income, thousands of investors were deeply involved in the case, involving up to 307 million yuan. Under the "veil of mystery" of the blockchain, the illegal elements have taken advantage of their own tricks, and the blockchain has become a "signboard" of economic crimes such as fraud and pyramid selling

why is the blockchain repeatedly "misused" by illegal activities such as pyramid selling fraud? In addition to "unknown", what is the "function" of blockchain technology itself? Since the beginning of this year, with the increase of supervision and the cooling of currency speculation, new opportunities have been brought to the development of blockchain. How about the implementation of blockchain commercial "application" The reporter of outlook news weekly recently concted an investigation

when the three-month "capital release period" promised by the trading platform expired and the staff began to "kick" in the QQ group, Tang Haiyan, who lives in Bao'an District of Shenzhen City, realized that she might have been cheated

previously, Tang Haiyan invested 80000 yuan to buy a virtual currency called "ordinary silver coin" under the introction of her classmates“ The other side said that this currency is the most advanced blockchain technology at present, with Tibetan tea as collateral. He also showed me the "technical white paper". I didn't understand blockchain, so I didn't read it carefully. "

although she doesn't know about blockchain and virtual currency, the high investment income makes Tang Haiyan full of expectations. She told reporters that companies issuing "ordinary silver coins" will regularly split the virtual currency according to the ratio of 1:10, which means that each split will make the value of "ordinary silver coins" in the hands of investors expand 10 times. As long as after a split, her investment of 80000 yuan is equivalent to the purchase of 800000 yuan worth of "ordinary silver coins", which can be sold on the trading platform to obtain huge profits

according to the rules of the trading platform, the newly purchased "ordinary silver coin" cannot be traded immediately, and it must be frozen on the platform for three months before it can enter the "release period". However, after three months, not only did Tang Haiyan not wait for the assets to double, but the 80000 yuan frozen on the platform could not be used for trading

"other investors began to question the authenticity of this investment in QQ group. As a result, the staff of the company kicked these investors out one by one, which made me feel bad." She said

Shenzhen police investigation found that the company claimed that investors could buy and sell "ordinary silver coins" on the virtual trading platform "jucoin net" to earn a price difference

. In fact, the change of its trading price is that the company used investors' investment funds for behind the scenes operation, and once raised the price of "ordinary silver coin" from 0.5 yuan to 10 yuan, so that investors can taste some sweetness. When a large number of investors entered the market, the company continued to cash out through malicious manipulation of the price trend of "ordinary silver coin", which eventually led to the worthlessness of "ordinary silver coin" in the hands of investors

since 2018, engaging in fraud and pyramid selling under the banner of blockchain has become a common "routine" in new criminal tactics. In April 2018, Jinan police dropped a pyramid selling Gang under the guise of "western development", "national poverty alleviation", "original stocks", "blockchain" and "e-commerce", arrested more than 10 major suspects, frozen more than 100 accounts involved, and seized more than 300 million yuan of funds involved

according to Jinan police, huileyi e-commerce company designed a fake virtual disk on the Internet on the ground that the country is vigorously developing the big data instry, and released a variety of virtual currencies such as "precious currency" and "precious currency"

under the guise of giving away, they presented a certain amount of virtual currency to the New MLM staff, with the price of tens of yuan each. Then, through artificial manipulation, they appreciated the virtual currency all the way to more than 100 yuan or even hundreds of yuan, attracting people who did not know the truth to join. Finally, they "cut leeks" through the periodic fluctuation of the so-called "devaluation" of virtual currency, Finally, the purpose of seeking illegal interests is achieved

in Xi'an, a few days ago, the local police successfully cracked a huge network pyramid selling case under the banner of blockchain. According to the police, the suspect, Zheng Mou, has paid a high salary to the 9 network members, such as Zhang and Lee. Since March 28, 2018, he has gathered pyramid selling and network pyramid selling as a means to sell the virtual Datang coins at the consumption era network platform at the price of 3 yuan each, and manipulate the appreciation rate; p>

at the same time, promotion meetings were held in many cities at home and abroad to attract members. According to the development of members, 28 level agents were set up. In just 18 days, the gang developed more than 13000 registered members. At present, it has been found that the case involves 31 provinces, cities and autonomous regions in China, and the fund involved is as high as 86 million yuan

according to Tencent's 2017 pyramid selling situation awareness white paper released by Tencent security joint laboratory, in recent years, all kinds of overseas capital disk, virtual currency and ICO (initial public offering token financing of blockchain project) projects have emerged in an endless stream, which hide many risks such as illegal issuance, untrue projects, cross-border money laundering, fraud and pyramid selling, As a result, a large number of funds flow overseas. Once the market collapses, runs away or loses contact, investors often have no way to complain and the losses are difficult to recover. For example, Baichuan coin, mark coin, beta coin, dark coin, etc

the reporter of lookout Newsweek interviewed in Guangdong, Shandong, Shanghai and other places and learned that most people know that the concept of blockchain is very popular, but they "don't know where it is", and there are different opinions on the specific functions of blockchain: some people think it is used for "investment and financing", "buying and selling currency", while others think it is "a major invention of the same magnitude as the steam engine", Some entrepreneurs are even more eager to seize this "once-in-a-lifetime opportunity to get rich."

many people in the instry said that it is precisely because people have many misunderstandings about blockchain that criminals have opportunities to fish in troubled waters and mislead investors

in many instries, we media and celebrities form interest alliances with issuers and digital exchanges to endorse and create public opinion for the "air currency" project. In December last year, nine departments including the people's Bank of China identified ICO as "suspected of illegal fund-raising, financial fraud, pyramid selling and other illegal and criminal activities"

in the interview, many people told our reporter that the existence of token has built a set of rights and interests mechanism for the development of blockchain technology, which is indispensable for stimulating the prosperity of blockchain applications“ The market practice in the past five years has proved that blockchain applications without equity mechanism are just like market economy without computers connected to the Internet and money, with greatly reced application scenarios and development speed. " An investor in Shanghai said

in fact, the token represented by bitcoin is only one of the earliest procts to verify the blockchain technology, and the two can not be equated, and the existence of token has obviously negative effects on the development of blockchain

Xiao Wei, chief engineer of network blockchain, told this reporter that the myth of ICO's sudden wealth shakes the R & D concentration of blockchain technical talents, and the myth of "sudden wealth" with hundreds of times of return tests the patience of blockchain technical R & D talents“ Many of the "comrades in arms" in the circle who used to do research and development of blockchain technology have gone to issue coins, and now few of them can insist on doing research and development and application of technology. "

Xu zewei, Secretary of the Party committee of Beijing Internet Finance Instry Association, said that under the background of China's ban on ICO, many domestic start-ups promoting blockchain applications are "selling dog meat with sheep's pawn" and financing through concept packaging of worthless tokens“ ICO has polluted the good atmosphere of innovation and entrepreneurship, and created a kind of speculative proct. Many young people are not thinking about entrepreneurship, but are thinking about issuing money, which makes us have the illusion of getting rich overnight. "

at present, more and more people in the instry begin to think about whether the development of blockchain must rely on the issuance of tokens to achieve incentives. Guo Dagang, Secretary General of Beijing Internet Finance Instry Association, told this reporter that the so-called incentive mechanism is only the theoretical basis for the project party to issue tokens for itself. Huo Xuewen, director of Beijing Municipal Bureau of financial work, also believes that if blockchain does not get rid of the dilemma of issuing currency, it will never find a legal landing mechanism

secondly, blockchain is not omnipotent and its security is at risk. Blockchain is generally considered to achieve three functions:

first, the data stored on the blockchain can not be tampered or forged, and the data has high credibility and credibility; Second, the whole process of the transaction can be traced, which can achieve accurate responsibility tracking; Third, the embedded smart contract in the blockchain can be executed automatically based on the contract, so as to improve work efficiency and rece the risk of default. It is generally believed that blockchain has broad application prospects in finance, logistics, trade and other fields

in fact, blockchain is not omnipotent, and its function has many limitations. It is generally believed that, according to the characteristics of cryptography, in order to tamper or falsify in the blockchain, more than 51% of the nodes need to be controlled in theory. When there are enough nodes in the blockchain, it is difficult to tamper with the trust creation mechanism widely participated by the public

Zhao Yao, a special researcher of the Institute of finance of the Chinese Academy of Social Sciences, told this reporter that the academic community has confirmed as early as 2013 that the blockchain is not perfect and there are many "cheating" strategies. As long as there are enough economic incentives, controlling attacks of more than 51% nodes does not only exist in theory

Zeng Guang, Secretary General of Shenzhen Internet Finance Association, said that the blockchain technology itself does not have the ability to do so

blockchain is a decentralized distributed ledger database . The advantage of this distributed ledger is that buyers and sellers can trade directly without any intermediary. Everyone has a backup, even if you lose this, it will not be affected

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blockchain application field

1, financial field

blockchain has potential huge application value in international exchange, letter of credit, equity registration, stock exchange and other financial fields. The application of blockchain technology in the financial instry can save the third-party intermediary link and realize the point-to-point direct docking, so as to greatly rece the cost and quickly complete the transaction payment

2. The Internet of things and logistics

blockchain can also be naturally combined in the field of Internet of things and logistics. Through blockchain, we can rece logistics costs, trace the proction and delivery process of goods, and improve the efficiency of supply chain management. This field is considered as a promising application direction of blockchain

3. The data stored on the public welfare field

blockchain is highly reliable and tamperable, which is naturally suitable for social public welfare scenarios. The relevant information in the public welfare process, such as donation project, collection details, fund flow, recipient feedback, etc., can be stored on the blockchain, and can be made transparent and public, which is convenient for social supervision

4. In the field of insurance

in terms of insurance claims, insurance institutions are responsible for fund collection, investment and claims settlement, and often have higher management and operation costs. Through the application of smart contract, there is no need for the applicant to apply or the insurance company to approve. As long as the claim conditions are triggered, the automatic claim settlement of the policy can be realized

Let's suppose villagers Lao Wang and Xiao Li. Lao Wang borrowed some money from Xiao Li, who wrote it in an IOU signed by both parties. A few days later, Lao Wang denied the existence of borrowing money and claimed that Xiao Li forged the paper. Xiao Li can't argue because he finds it difficult to prove that Lao Wang actually owes him money

in this example, Lao Wang and Xiao Li are two nodes

now assuming the same scenario, there are many pairs of people trading with each other in the village. The only evidence for each pair is the IOU. If one party fails, it will be difficult to do so. Seeing this scene, the village head came up with a solution. He suggested using a common notebook for the whole village to record all the transactions. Due to the high prestige of the village head, the villagers unanimously decided to let the village head keep this important transaction book. Each transaction, the villagers go to the village head's home, let the village head witness and record, each transaction is written into a notebook, and then safely saved. That notebook can be called a database

because this notebook is very important, the village head locked it in the safe. However, there are always some problems. Sometimes, the village head will accidentally sprinkle ink on the paper, making some transaction records illegible. This is called a single point of failure. The thief knows that there is an important notebook in the safe of the village head's house. He tries his best to steal it. This is called hacking

until one day, the village head's son owed others a lot of money, so the village head secretly deleted his son's debt entry. In this way, the village head's son "does not owe money."

when the villagers knew this, they began to question the fairness and authority of the village head. So some people put forward a new idea:

abolish the power of the village head, which is called decentralization. Let all villagers keep a notebook, and the transaction records are copied and distributed, which is called distributed database. Therefore, if there are n people in the village, there are n notebooks, that is, n nodes. Every time there is a trade between any two people, all the people in the village get together and record it in their notebooks. And no one can cover the sky. This is called decentralization

they also decided that they would never delete the mentioned transactions from their notebooks, which is irreversible. For example, Lao Wang borrowed a sum of money from Xiao Li before, but in the twinkling of an eye, he wants to return the money. Then the transaction book will not delete the previous borrowing record, but write a new repayment record, so there are two records

next, let's try to break this rule. What if we bribe Lao Wang to change his notebook? It's not feasible, because the next time the villagers meet, they find that Lao Wang's notebook is different from everyone else's, so the villagers notice that Lao Wang may be engaged in an indescribable transaction, and decide to abolish Lao Wang's transaction record and kick Lao Wang out of the organization

What if you try to bribe all the villagers? It's too expensive

the characteristic of this model is that greedy people need to pay a lot to attack the rules. He will find it more profitable to follow the rules

a smart child in the village suggested that each transaction data be called "block" and linked into a "chain" in chronological order, which is called blockchain