How does blockchain save bills

3. 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 />}
}

4. 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.

5. The registered digital assets are stored in the blockchain. In essence, the blockchain is a decentralized distributed ledger database, which is a series of data blocks generated by the use of cryptography, and its characteristics are unchangeable and unforgeable. Similar to the digital asset registration business done by gold owners, it uses blockchain to store digital assets. In this way, every registration record of the platform can be traced, forged and tampered with. It is precisely because of this characteristic that when users have ownership disputes, such data can have credibility and can be provided to administrative departments as the basis for law enforcement.

6.

Many small white just admission, was the private key, public key, address, and other relations confused. Some of them even lost their private key. They had money on the address, but they just couldn't get it out. Today, Xiao will try to figure out the relationship between the private key, the public key and the address

The relationship among < H2 > private key, public key and address is as follows:

the private key is converted into (generated) public key, and then converted into address. If there is bitcoin or integrity coin on an address, the private key converted into the address can be used to spend the above integrity coin. The generation of public key and address depends on private key, so private key is the most important

mobile wallet is the same, but the file management method of mobile phone is not as convenient as computer. Therefore, the general mobile wallet will provide a function called or similar to "export private key". Through this function, the private key can be exported in various forms

for example, bitcoin mobile wallet can be exported as a two-dimensional code, which can be printed or scanned on paper. When replacing a mobile phone, install a bitcoin wallet and scan the QR code to migrate bitcoin. Bitcoin mobile wallet and trustcoin mobile wallet can be exported as a clear text string and printed on paper - this is paper wallet

paper wallet allows users to spend your bitcoin or trustcoin at any terminal with bitcoin or trustcoin wallet

because the wallet is lost or damaged, the private key will be lost, and the transfer right of the digital currency will be lost completely. To prevent such tragedies, you should always back up the data in your wallet. In addition to the address, all the private keys are saved ring the backup

< H2 > summary

1. the private key should be protected to prevent loss and forgetting. When the mobile phone clears the information, it is best to it by hand, but do not disclose it

2. you should prevent your wallet from being lost or damaged, resulting in the loss of your private key and the loss of the transfer right of digital currency. Otherwise, you will not be able to withdraw more money, which is not useless