File blockchain

1.

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 information of bitcoin network transactions, Used to verify the validity of its information (anti-counterfeiting) and generate the next block

extended data

most blockchain public chains are limited by scalability. The biggest feature of blockchain technology is decentralization, which requires that all accounts in the network need to deal with the accounting process. Distributed accounting has high security, low misoperation rate, political neutrality and correctness

however, blockchain technology embraces these features at the same time, sacrificing scalability, unable to meet the personalized supervision, and slightly insufficient in protecting data privacy. Moreover, with the increase of the number of ledger, the interaction delay will increase exponentially, that is to say, the more ledger in the blockchain network, the higher the delay

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. How to store information on the blockchain: call the API provided by the blockchain platform

generally, the blockchain platform will provide corresponding interfaces, such as RPC, json-rpc, HTTP, etc. of course, the platforms are not the same, and the degree of friendliness is different

some companies specializing in API, such as blockcypher, can provide friendly calling interfaces, and it is not very convenient to write answers on the mobile phone, Search below

as for the storage content, add a point: in addition to the conventional cloud storage, file entities on the file hash record chain also have blockchain based storage schemes, such as IPFs, storej and so on

4. Bitcoin market suddenly soared, and now you can buy it. But you have to buy by yourself. Think about it, because bitcoin is a virtual currency. Market uncertainty, buy carefully.

5. In SEG computer city, take No. 527 and No. 9, and get off the National Exhibition Center. Network map
let's see what others say.

6.

Interstellar document (Shenzhen) blockchain Co., Ltd. is a limited liability company incorporated on August 17, 2018, with its registered address at 103, block D, No. 1 ChuangJin, 28 District, Dalang community, Xin'an street, Bao'an District, Shenzhen

the unified social credit code / registration number of star file (Shenzhen) blockchain Co., Ltd. is 91440300ma5f9dc35h, and the enterprise legal person is innovative. At present, the enterprise is in business

the business scope of star file (Shenzhen) blockchain Co., Ltd. is: general business items are: blockchain, Internet of things, artificial intelligence technology development, technology transfer; Research and development of big data technology; Technical development of digital integration system; Technical development and sales of computer software and information system software; Sales of mechanical equipment, hardware procts, electronic procts, computers, software and auxiliary equipment; Design and technical maintenance of information system; Information technology consulting; Design and development of integrated circuits; Sales and leasing of mining machinery and equipment (excluding financial leasing); Provide management services for enterprises; Import and export business Except for the above items that are prohibited by laws, administrative regulations and decisions of the State Council, the restricted items can only be operated after obtaining permission). The permitted items are: vocational skills training

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