Transaction receipts are stored in the blockchain

1. Imapp2.0 version of blockchain application center has been officially launched
imapp2.0 version of blockchain application center has been officially launched. Imapp is the world's first blockchain app store with universal dividends, which aims to create a super entrance to the blockchain instry and make it easier for users to use blockchain applications. The interface of imapp 2.0 is more concise and beautiful, the function adds news and DAPP, and the content enriches the guessing game. Through imapp, users can browse, forward, download, update and open the application to obtain imapp ecological token IA. The official imapp has reached a strategic cooperation with the bitcoin diamond foundation. Ecocard ia can exchange bitcoin diamond BCD at a certain proportion.

2. const SHA256 = require(crypto-js/SHA256);< br />class Block{
constructor(index,timestamp,data,previousHash='&# 39;)< br />{
this.index=index;< br />this.timestamp=timestamp;< br />this.data=data;< br />this.previousHash=previousHash;< br />$this.hash=this.calculateHash();< br />}

calculateHash(){
return SHA256(this,index+this.previousHash+this.timestamp+JSON.stringify(this.data)).tostring();< br />}
}
class Blockchain{
constructor(){
this.chain=[this.createGenesisBlock()];<
}
/ / create a generated information block
creategenesis block() {
return new block (0, & quot; 01/01/2019",& quot; Genesis block", 0);
/ / the date is the user's data. In fact, it is the hash value obtained by adding several values together. Here, the information is encrypted and the picture is encrypted. Then the data is still stored in the database, but all the data are hash values. To get this data, you must know the hash value of the previous data block. Then, if the hacker needs to crack all the nodes, the hash value is decrypted, Then all the blocks from the first node to the last node can be decrypted to get the real data. So the security of data stored in the blockchain depends on whether the data is encrypted. If the plaintext is not encrypted, then it is not a blockchain
}
/ / get the last block
getlatesblock() {
return this.chain [this.chain. Length-1]
}
/ / create block
addblock (newblock) {
newblock. Previoushash = this. Getlatesblock(). Hash< br />newBlock.hash=newBlock.calculateHash();< br />this.chain.push(newBlock);< br />}
}

3. The information of each block in the blockchain is different, and the generation time and recorded data of each block are different. You can regard the blockchain as a bookkeeping book. Every once in a while, someone will write all the transaction information on the blockchain network to one page of the ledger, page by page, and record all the transactions on the blockchain network in turn according to the time
on the other hand, all nodes (computers in short) participating in the network will store one account book, which is updated in real time. Even if one node fails, the blockchain will not be affected.

4.

The global well-known blockchain trading platform can refer to the following figure:

there are many similar platforms, which can be viewed on non small platforms. The market of digital assets fluctuates a lot, and no one can say for sure. Compared with the previous boom, the current market is in the cooling stage

blockchain is the core supporting technology of digital cryptocurrency system represented by bitcoin. The core advantage of blockchain technology is decentralization. It can realize point-to-point transaction, coordination and cooperation based on decentralized credit in a distributed system without mutual trust by means of data encryption, time stamp, distributed consensus and economic incentive, so as to solve the common high cost, low cost and low cost of centralized institutions Low efficiency and data storage insecurity provide solutions

the application fields of blockchain include digital currency, token, finance, anti-counterfeiting traceability, privacy protection, supply chain, entertainment, etc. with the popularity of blockchain and bitcoin, many related top domain names have been registered, which has a great impact on the domain name instry

5. The relationship between blockchain and big data storage is as follows:
first, data security: blockchain makes data flow "at ease"
with its trustworthiness, security and non tamperability, blockchain liberates more data. A typical case is used to illustrate how blockchain promotes the generation of big data for gene sequencing. Blockchain sequencing can use the private key to limit access rights, so as to avoid the legal restrictions on indivial access to gene data, and use distributed computing resources to complete the sequencing service at low cost. The security of blockchain makes sequencing an instrialized solution, realizing global scale sequencing, thus promoting the massive growth of data< Second, data open sharing: blockchain guarantees data privacy
the government has a large number of high-density and high-value data, such as medical data, population data, etc. The opening of government data is the general trend, which will have an inestimable impetus to the development of the whole economy and society. However, the main difficulty and challenge of data opening is how to open data while protecting personal privacy. Data desensitization technology based on blockchain can ensure data privacy and provide a solution for data opening under privacy protection. Data desensitization technology mainly uses hash processing and other encryption algorithms. For example, enigma based on blockchain technology can protect the privacy of data and eliminate information security problems in data sharing by computing data without accessing the original data. For example, employees of a company can safely open the path to access their salary information and jointly calculate the average salary within the group. Each participant can know his or her relative position in the group, but he or she knows nothing about the salaries of other members< The schematic diagram of data hash desensitization processing
3. Data storage: blockchain is a kind of database storage technology that can not be tampered with, full history, strong endorsement
blockchain technology, through all nodes in the network participate in the calculation together, and verify the authenticity of their information to achieve the consensus of the whole network, it can be said that blockchain technology is a specific database technology. So far, our big data is still in a very basic stage. The data based on the consensus of the whole network and the reliable blockchain data are tamperable and historical, which makes the quality of the data gain unprecedented strong trust endorsement, and also makes the development of the database enter a new era< Data analysis: blockchain ensures data security
data analysis is the core of realizing data value. In data analysis, how to effectively protect personal privacy and prevent core data leakage has become the primary consideration. For example, with the application of fingerprint data analysis and the popularization of genetic data detection and analysis, more and more people worry that once personal health data is leaked, it may lead to serious consequences. Blockchain technology can prevent this kind of situation through multi signature private key, encryption technology and secure multi-party computing technology. When the data is hashed and placed on the blockchain, the use of digital signature technology can enable those authorized people to access the data. The private key not only ensures the privacy of data, but also can be shared with authorized research institutions. The data is stored on the decentralized blockchain and analyzed without accessing the original data. It can not only protect the privacy of the data, but also provide it to the global scientific research institutions and doctors for sharing. As the basic health database of all mankind, it will bring great convenience to solve the sudden and difficult diseases in the future
v. data circulation: blockchain protects the rights and interests related to data
for valuable data assets of indivials or institutions, blockchain can be used to register them. Transaction records are recognized, transparent and traceable throughout the network, making clear the source, ownership, use right and circulation path of big data assets, which is of great value to data asset transaction
on the one hand, blockchain can break the threat of intermediary ing data, which is concive to the establishment of a trusted data asset trading environment. Data is a very special commodity, which is essentially different from ordinary commodities. It is mainly characterized by unclear ownership and "being owned after seeing and ing", which also determines that the traditional commodity intermediary transaction method can not meet the needs of data sharing, exchange and transaction. Because the intermediary center has the conditions and the ability to and save all the flowing data, it is extremely unfair to the data procers. This threat can not be eliminated only by commitment, and the existence of this threat has become a huge obstacle to the flow of data. Based on the decentralized blockchain, it can break the threat of ing data in the intermediary center and protect the legitimate rights and interests of data owners
on the other hand, blockchain provides a traceable path, which can effectively solve the problem of data right confirmation. Through multiple nodes participating in the calculation in the network, blockchain can participate in the calculation and recording of data together, and verify the effectiveness of their information. It can not only carry out information anti-counterfeiting, but also provide a traceable path. The transaction information of each block is strung together to form a complete detailed list of transactions. The context of each transaction is very clear and transparent. In addition, when people have doubts about the "value" of a block, they can easily trace back the historical transaction records, and then judge whether the value is correct, and identify whether the value has been tampered or recorded incorrectly
with the protection of blockchain, big data will naturally become more active
the tokens of crowdfunding projects on coin Ying China platform are all developed based on blockchain technology, and relevant information will be recorded on the blockchain.

6.

In the traditional supply chain finance, financing difficulty, high financing cost and cumbersome financing process have always been one of the bottlenecks restricting small and medium-sized enterprises to become bigger and stronger. Banks rely on the ability of core enterprises to control goods and regulate sales. For the sake of risk control, banks are only willing to provide factoring services to upstream suppliers (limited to first tier suppliers) with direct accounts payable obligations of core enterprises, or provide prepayment or inventory financing to their downstream distributors (first tier suppliers). As a result, the demand of secondary and tertiary suppliers / distributors with huge financing demand can not be met, the business volume of supply chain finance is limited, and the small and medium-sized enterprises can not get timely financing, which will easily lead to proct quality problems and damage the whole supply chain system

to solve these problems, we can make use of the characteristics of decentralized, tamper proof and distributed ledger of blockchain technology to build a blockchain supply chain financial platform

The core enterprise issues a / R certificate to the distributor. After the distributor signs the receipt, it indicates that it has signed the purchase and sales contract and the core enterprise delivers the goods

Because of the shortage of funds, distributors need to borrow money from finance

3. After the financial institutions have approved, the amount of loans will be sent to the core enterprises

The distributor will repay the loan and interest after selling the goods

7. Encryption code. Every few minutes, a new block is generated, which stores different information and consists of different passwords (double keys).

8.

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