Read blockchain in one article

1.

If you want to understand the application of blockchain, you can refer to many books and opinions, such as illustrated blockchain, blockchain: reshaping the economy and the world, blueprint and guide of new economy, and articles of coin'an community, including a detailed understanding of the platform of coin'an community, with great strength

As the name suggests, blockchain is composed of block and chain. It is a new application mode of computer technology such as distributed data storage, point-to-point transmission, consensus mechanism, encryption algorithm and so on. It is a kind of chain data structure that combines data blocks in order according to the time sequence, and it is a secure and reliable distributed account book that can not be tampered with and forged by means of cryptography

in 2008, in his paper bitcoin: a peer-to-peer e-cash system published by Nakamoto, he first proposed the idea of blockchain and encrypted digital currency. Starting from bitcoin, blockchain has become the underlying technology of various digital currencies

Second, the working principle of blockchain:

1. The basic concepts include: (1) transaction: one operation will change the account status once, such as adding a record 2) Block: records the transaction and status data within a specified time, which is a consensus and preservation of the current account status 3) Chain: it is composed of a series of blocks in chronological order, which is the log record of the whole state change. If you understand the working concept of blockchain, it is not difficult to understand its working principle. Suppose there is a distributed data logbook, which can only be added, not deleted or changed. Its structure is a linear chain formed by a series of "blocks" (which is also the source of the name of "blockchain"), and new data must be put into a new block to be added, The maintenance node can propose a new block, but it must go through a certain consensus mechanism to reach an agreement on the final selected block

2. Take bitcoin as an example to see the working principle of blockchain

the block of bitcoin is divided into block head and block body

Core advantages and characteristics of blockchain

1. The verification, accounting, storage, maintenance and transmission of decentralized blockchain data are all based on distributed system structure. There is no centralized hardware or management organization, and the rights and obligations of any node are equal, The data blocks in the system are jointly maintained by the nodes with maintenance function in the whole system. 2. The open and transparent system is open. In addition to the private information of all parties to the transaction is encrypted, the data of the blockchain is open to all. Anyone can query the blockchain data and develop related applications through the open interface, so the information of the whole system is highly transparent. 3. Security blockchain uses consensus based specifications and Protocols (such as a set of open and transparent algorithms) to enable all nodes in the whole system to exchange data freely and safely in a de trusted environment, so that the trust in "people" is changed into the trust in machines, and any human intervention does not work. 4. Information cannot be tampered with. Once the information is verified and added to the blockchain, it will be stored permanently. Unless more than 51% (almost impossible) nodes in the system can be controlled at the same time, the modification of the database on a single node is invalid. Therefore, the data stability and reliability of the blockchain are extremely high. 5. Anonymity because the exchange between nodes follows a fixed algorithm, and its data interaction does not need trust (the program rules in the blockchain will judge whether the activity is effective or not). Therefore, the counterparties do not need to let the counterparties generate their own trust by disclosing their identities, which is very helpful for credit accumulation

At present, the most popular classification of blockchain is to divide blockchain into public blockchain, private blockchain and consortium blockchain according to different participants

1. Public chain: anyone can participate in the use and maintenance, and can obtain the effective confirmation of the blockchain. Public chain is the earliest blockchain and the most widely used blockchain at present, such as bitcoin blockchain. The information is completely public

if the licensing mechanism is introced, it includes private chain and alliance chain. 2. Private chain: a company or indivial only uses the blockchain technology, enjoys the exclusive write permission of the blockchain, and does not disclose the information. At present, conservative giants (traditional finance) want to experiment with private blockchain, and the application procts of private blockchain are still groping. 3. Alliance chain: it is a blockchain between the public chain and the existing chain, which is jointly controlled by multiple organizations. The use of the chain is managed with authority, which can be controlled by the manager, and also open to others according to the manager's wishes. In addition, according to the different use scenarios and purposes of blockchain, it can be divided into currency chain for the purpose of digital currency, property chain for the purpose of recording property rights, and crowdfunding chain for the purpose of crowdfunding

On May 28, Ma Huateng, CEO of Tencent, proposed the anti-counterfeiting method based on cloud integrated blockchain technology, which is far more efficient than traditional anti-counterfeiting methods. The future anti-counterfeiting verification scenario may only require users to use their mobile phones for simple scanning, and a large number of complete information based on different dimensions can be obtained

take Maotai liquor as an example:

distillery address, proction workshop, operation staff, inspector, delivery time, transportation vehicle information and driver information,

liquor year, raw material source, raw material supplier, storage warehouse number, raw material transportation vehicle and driver information,

all information can be accurately traced, permanently recorded and tampered with

the above information can be easily verified

2. Food safety issues as early as last November, Wal Mart has cooperated with IBM to track the source of food by using blockchain technology, so as to ensure the safety of food and increase the circulation of food to rece costs. For Wal Mart and other large supermarkets, it took a few days to investigate the source of problem food, After using this technology, only one item of proct information is needed to achieve accurate traceability, and important information such as food origin, inspector, supplier, logistics and transportation can quickly find problems in a few minutes. Currently, procts tracked by blockchain include packaging procts from the United States and pork from China

3. Information security

blockchain technology is promoting an information security technology revolution. (1) identity protection PKI is a common public key encryption technology in e-mail, message application, website and other communication applications. However, since the implementation of most PKI, the centralized trusted third party certification authority (CA) is used to issue, activate and store user certificates. Hackers can attack PKI to fake user identity or crack encrypted information

certcoin is the first PKI implementation of blockchain, which comes from MIT, removes the centralized authentication center, and uses blockchain as a distributed ledger for domain name and public key

pomcor company: blockchain PKI implementation path: keep the authentication center, and use blockchain to store the hash value of issued and activated certificates. Users can verify the authenticity of certificates through decentralized and transparent sources, and can also improve the network access performance through local authentication of secret key and signature based on blockchain

(2) data integrity protection

guardtime developed a secret key free signature architecture (Ksi) based on blockchain technology to replace the secret key based data authentication technology. Ksi stores the hash table of the original data and files on the blockchain, runs the hash algorithm to verify other copies, and compares the results with the data stored in the blockchain. Any data tampering will be found quickly because the original hash table is stored in millions of nodes

(3) key infrastructure protection

the "Achilles heel" of the Internet, DDoS has entered the TB era, DDoS is still the simplest weapon for hackers to bring down the big target with low cost, DNS service is the primary target for hackers to carry out large-scale destruction, but blockchain technology is expected to fundamentally solve the problem

The distributed storage of

blockchain makes hacker attacks lose focus. Nebulis is developing a distributed DNS system, which uses Ethereum blockchain and interstellar Internet file system (IPFs, the distributed substitute of HTTP) to register and resolve domain names. The biggest weakness of DNS is caching, which makes DDoS attacks possible. It is also the bane of the centralized government's censorship of social networks and manipulation of DNS registration. A highly transparent and distributed DNS system can effectively prevent any entity, including the government, from arbitrarily manipulating records

(1) digital currency: improve the convenience of currency issuance and use, such as bitcoin and Ethernet in foreign countries, and guorenbao in China

from the use of physical transactions, to physical currency and credit currency, and then to the rise of bitcoin network, more and more people are aware of the distributed ledger blockchain technology behind it, and graally apply it in many scenarios other than digital currency

(2) cross border payment and settlement: realize point-to-point transaction, rece intermediate fees

transfer and payment. At present, the most mature application of blockchain technology is payment and transfer. Blockchain technology can avoid complicated systems, save the process of inter-bank reconciliation and review, and accelerate the settlement speed; Virtual currency can rece transaction costs without the intervention of clearing house. Different countries have different clearing proceres. It takes two or three days for a single remittance to arrive, which is inefficient and accounts for a large proportion of funds in transit. No longer through the third party, through the blockchain technology to form point-to-point payment. By eliminating the link of the third-party institutions, we can make full day payment, real-time payment, withdraw cash quickly and rece the hidden cost, which helps to avoid the capital risk. It is timely and convenient

(3) bills and supply chain financial business: rece human intervention, rece costs and operational risks

value transfer between point-to-point, control and verify physical bills or central system; Intermediaries will be eliminated and human intervention reced. With the improvement of efficiency, financing channels are more unblocked, risks are lower, and multiple parties benefit

(4) securities issuance and Trading: realize quasi real-time asset transfer, accelerate the speed of transaction clearing

the application of blockchain technology can make the process of securities trading more concise, transparent and fast, rece the plication of IT system, and improve the efficiency of market operation. For stocks, blockchain can eliminate paper and pen or electronic form records, rece human errors in trading, and improve the transparency and traceability of trading platform. Citigroup and Nasdaq cooperate to promote blockchain applications

(5) customer credit investigation and anti fraud: rece the cost of legal compliance, prevent financial crimes

the customer information and transaction records recorded in the blockchain help banks identify abnormal transactions and effectively prevent fraud. The technical characteristics of blockchain can change the existing credit reference system, and store the data of customers with bad records in the blockchain when the bank concts "know your customer" (KYC)

equity crowdfunding:

2.

Blockchain is a kind of technology, which solves the core "trust" problem in the market economy and reces the trust cost between strangers to a very low level

there is one crucial thing in the market economy, which is "trust". Without trust, no deal can be established. When you go to LAICHANG to buy vegetables, if you don't believe that the pesticide content in vegetable is up to the standard, you won't trade with that dealer; If you buy a bottle of water in a small shop, the clerk will not sell you the water if he doesn't believe that the money you give is real

the traditional small-scale peasant economy is acquaintance economy, and the transaction scale is limited to people who are familiar with each other nearby. If an acquaintance deceives you, he will lose your social relationship and damage his reputation in the whole circle of acquaintances. We believe that acquaintances are less likely to cheat us than strangers

therefore, once we are beyond the scope of acquaintances, we need to use a high cost to identify whether a stranger will cheat me and how to avoid the risk of being cheated. This situation will hinder the transaction and restrict the transaction

in addition, different races, nationalities, cultures, religious beliefs and so on will naturally have this kind of trust problem

in the market economy, why can there be so many transactions between strangers? Because of the birth of a new mechanism to solve the problem of trust in strangers

so far, the most important mechanism to solve the trust problem is the "trust intermediary" organization and mode

as long as you and strangers trust a third-party organization, the trust problem between you can be solved through this third-party organization

this third-party organization, we call it trust intermediary. Both the government and the bank are trust intermediaries

you can sell the goods you have worked hard to proce to a stranger in exchange for a stack of RMB banknotes. It's because the credit of the note issuing bank and the guarantee of the authority of the government guarantee the currency value and effectiveness of the banknotes. Otherwise, sell things, in exchange for a few ordinary paper, who would like to

in the era of global village and Internet, the people who buy your things may be strangers who will not meet and thousands of miles away. Trust is lower, so Alipay assumes the role of trust intermediation. Buyers first pay the goods to Alipay's account. When they receive the goods, they confirm that they are OK, then they agree to sell the goods to the seller. Taobao and other e-commerce have been booming rapidly in just over ten years

trust intermediary is in a central position in the transaction system. All transactions should solve the trust problem through it

However, the cost of trust intermediary itself is often huge

as a trust intermediary, how much transaction tax does the government charge each year? What is the most profitable instry? Financial services. The annual profits of Alipay's ant suit are over ten billion. p> What does this mean? Both sides of the market actually pay a huge trust cost

if there is any way to cancel or greatly rece the trust cost, the transaction cost of the general public can be reced, and the profits can be greatly increased

so in the Internet era, blockchain technology is on the stage

it allows the trading party to get rid of the intermediary, solve the problem of trust among strangers, and greatly rece the cost of trust

the blockchain can be expanded on a large scale, the data is open and transparent, the data of each client is consistent, and even if some clients are destroyed, the data security will not be affected. These highly reliable technical features can solve the trust problem of strangers with low cost

this technology can be extended to all fields that can be digitized, such as digital currency, payment and clearing, digital bills, proof of rights and interests, credit reference, government services, medical records, etc

in the medium and long term, blockchain will be a revolutionary technology, which will bring about great social changes like the existing Internet, and has great investment value and money making opportunities

in the future, the companies that can combine blockchain with different scenarios to promote applications may be the next group of bat, the next Google, Microsoft and apple

as the first practical application of blockchain technology, bitcoin has been widely accepted and used all over the world. Millions of users and tens of thousands of merchants have accepted the payment of bitcoin as a digital currency, and the exchange value of bitcoin as a currency is growing. Even e to the consensus that the total amount is fixed and the long-term value is bullish, bitcoin has become a hedge asset similar to gold, and the price has skyrocketed

3. The following points are the characteristics of the blockchain summarized by jinwowo group:

1 - Decentralization: because the blockchain relies on each node to achieve system maintenance and ensure the authenticity of information transmission, it is based on distributed data storage without centralized management by a certain center, Therefore, the attack and tampering of a node will not affect the healthy operation of the whole network

2-DE Trust: the establishment of a connection between any two nodes does not need to trust each other's identity, and the data exchange between the two sides does not need the basis of mutual trust. Since all nodes in the network can act as "supervisors", there is no need to worry about fraud

3 - extensible: blockchain is an underlying open source technology, on which various kinds of extension, decentralized and distrusted applications can be realized<

4 - anonymization: the two sides of data exchange can be anonymous, and the nodes in the network can exchange data without knowing each other's identity and personal information

5 - Security and reliability: because the activities between any nodes are supervised by the whole network, and the database adopts distributed storage, for hackers, first, they can't disguise and cheat, Second, we can't control the network only by conquering a node.

4. Blockchain is a shared distributed database technology. Although the wording of a sentence about blockchain in different reports is different, the following four technical features are consensus
1. Decentralized: the left side of Figure 1 describes the centralized characteristics of today's financial system, and the right side describes the emerging decentralized financial system, which has no intermediary, and the rights and obligations of all nodes are equal. Any node that stops working will not affect the overall operation of the system
2. Trustworthiness: all nodes in the system can trade without trust, because the operation of the database and the whole system is open and transparent, and nodes cannot cheat each other within the rules and time range of the system
3. Collective maintenance: the system is maintained by all the nodes with maintenance function, and all the people in the system participate in the maintenance work together
4. Reliable database: every node in the system has the latest complete database , so it is invalid to modify the database of a single node, because the system will automatically compare and think that the same data record that appears most times is true
the blockchains of bitcoin, Ethereum and decent all have these characteristics.

5. The subversive characteristics of blockchain lie in the following four aspects: first, transparency. The data record of the blockchain system is transparent to the nodes of the whole network, and the update operation of the data record is also transparent to the nodes of the whole network, which is the basis of the trustworthiness of the blockchain system. Because the blockchain system uses open source programs, open rules and high participation, the data records and operation rules of the blockchain can be reviewed and traced by the nodes of the whole network, with high transparency< Second, openness. The blockchain system is open. In addition to the fact that the private information of the parties directly related to the data is always encrypted, the data of the blockchain is open to all (except the blockchain system with special permission requirements). Anyone or participating nodes can query blockchain data records or develop related applications through the open interface, so the information of the whole system is highly transparent< Third, information can not be tampered with. Once the information of the blockchain system is verified and added to the blockchain, it will be permanently stored and cannot be changed (except for private blockchain systems with special change requirements). Unless more than 51% of the nodes in the system can be controlled at the same time, the modification of the database on a single node is invalid, so the data stability and reliability of the blockchain are extremely high
Fourth, decentralization. Decentralization is the most basic feature of the blockchain, which means that the blockchain no longer depends on the central processing node and realizes the distributed recording, storage and updating of data. In the traditional centralized network, attacking a central node can destroy the whole system, while in a decentralized blockchain network, attacking a single node cannot control or destroy the whole network. More than 5% of the nodes in the master network are just the beginning of gaining control. 2019 is the first year for the commercial application of blockchain technology, and the stimulation of favorable policies will make the development of blockchain technology more stable
with the application of blockchain technology graally penetrating into many fields such as digital finance and Internet, we have a clearer understanding of the value of blockchain
blockchain has formed a situation of global competition, and all countries are seizing the development opportunities, let alone China; Therefore, there is no doubt that blockchain has become a national strategy.

6.

The application prospects of blockchain are mainly in the fields of finance, Internet of things and logistics, public services, digital rights and insurance

1. Blockchain has great potential applications in international exchange, letter of credit, equity registration, stock exchange and other financial fields. The application of blockchain technology in the financial instry can eliminate the third-party intermediary link and realize the point-to-point direct docking

2. Blockchain can also be naturally combined in the field of Internet of things and logistics, which is considered as a promising application direction of blockchain. The establishment of credit resources in the blockchain can double improve the security of transactions and improve the convenience of Internet of things transactions. It can save time and cost for the application of intelligent logistics mode

3. Blockchain is closely related to people's proction and life in public management, energy, transportation and other fields. The decentralized and fully distributed DNS service provided by blockchain can realize the query and resolution of domain name through the point-to-point data transmission service between nodes in the network

4. Through blockchain technology, works can be authenticated to prove the existence of text, video, audio and other works and ensure the authenticity and uniqueness of ownership. After the works are confirmed on the blockchain, the subsequent transactions will be recorded in real time to realize the full life cycle management of digital rights, and can also be used as a technical guarantee in judicial evidence collection

5. 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

extended data:

the core technology of blockchain

1. Consensus mechanism, through the voting of special nodes, completes the verification and confirmation of transactions in a very short time; For a transaction, if several nodes with unrelated interests can reach a consensus, it can be considered that the whole network can also reach a consensus. The goal of blockchain consensus mechanism is to make all honest nodes keep consistent blockchain views

2. Asymmetric encryption requires two keys for encryption and decryption, which are public key and private key. The public key corresponds to the private key. The public key is used in the process of data encryption, and only the corresponding private key can be used to decrypt; On the contrary, the private key is used to encrypt the data, and only the corresponding public key can be used to decrypt the data

7. Don't listen to others. You can apply all the time, at least until today
it's just that the requirements for applying for a license are much higher than before, and the difficulty is also increased, so some applicants can't meet the examination requirements, so they may tell you that they can't apply, but this is not the case
in addition, in other European countries, there are very few content licenses specifically for digital currency, many of which are related to traditional financial licenses, because there are also many projects involving payment business.

8. How blockchain can bring about a "revolution" in personal data protection
US media disclosed on the evening of 17 local time that Cambridge analysis, a British company deeply involved in the scandal of abusing personal privacy data, originally planned to launch a personal privacy data storage service and sell it in the form of encrypted currency through blockchain technology. The concept of personal information encryption and monetization is not new. The key to this idea is everyone's autonomy of personal information. Some people in the instry believe that blockchain technology may bring a "revolution" in personal data protection

in the era of big data, personal data is considered as precious as gold. Personal data leakage is worrying, but the vast majority of people can't be cut off from the Internet because of the fear of data collection. At present, enterprises, schools, hotels, social networking sites, etc., which are responsible for keeping personal information, often fail to take the responsibility. Experts believe that blockchain technology, as a "middleware" with encryption, trust, point-to-point, and difficult to tamper, is expected to solve this problem
the emergence of blockchain technology makes it possible for everyone to control their own personal data by transferring the control of personal data from Internet companies to users themselves. Through it, users' personal data can be associated with their personal digital ID card. Users can choose whether their digital ID card is anonymous, pseudonym or public. They can also access the blockchain application platform from any device anytime and anywhere to control their Internet personal data
for example, the information on the block chain of someone's ID number may be converted to a series of ciphertext, and the face image information is also encrypted. When he checked in at the hotel, he only sent the cipher ID number to the hotel through application. The hotel compares the information with the encrypted data on the block chain application, and does not need to know any real information of him, but as long as the encrypted data match the result, it can guarantee the check in.
at the same time, the development of big data and artificial intelligence needs a lot of user data resources. Users can selectively sell their personal data as cryptocurrency and receive certain returns. For example, if e-commerce needs user data to develop a new application, users can choose to sell their own shopping history data, but their address, account number and other information can still be kept confidential
in the field of gene sequencing, blockchain applications have begun to challenge the "way to make money" of traditional gene sequencing companies selling personal data
in recent years, gene sequencing services for ordinary people have been popular. Take "23 and me" chromosome biotechnology company in the United States as an example. Consumers only need less than $100 and a few mouthfuls of saliva to get family genetic information. If they pay another $80, they can get in-depth analysis of genetic health risks and other aspects based on the original data. However, the company was not satisfied with the revenue from sequencing services. It also sold millions of customer genetic data to pharmaceutical companies by classification and packaging. The Parkinson's disease data sold in early 2015 alone amounted to $60 million. Many similar biotech companies, while obtaining service income from consumers, resell the data of consumers to "earn double money"
in February this year, George church, a geneticist at Harvard University in the United States, founded "nebula gene", hoping to break this pattern through blockchain technology. The company plans to complete the whole genome sequencing at a price of less than US $1000. The cost is borne by the customers. In return, the customers can intuitively understand their own genetic information and corresponding disease risks, and also have the autonomy of sequencing data. The security of genetic information will be guaranteed by blockchain technology. At the same time, it will be encrypted and monetized, and it will be stored and sold according to customers' wishes
the company plans to launch a kind of "Xingyun coin" as the trading medium. Customers can exchange their genetic information into "Xingyun coin", and they can also use "Xingyun coin" to pay for their own sequencing expenses. Pharmaceutical companies can purchase "Xingyun coin" with traditional currency to obtain the genetic information data of ordinary people. The whole trading process is completed through the blockchain platform, Encryption is transparent and secure
chech said that after integrating the cost of sequencing, genetic information protection, data management, genome big data processing and other factors, blockchain technology allows more people to truly "own" their own genetic information.