Simple blockchain demo implemented by golang

Posted by Blekk on Tue, 24 Dec 2019 20:10:09 +0100

The principle will not be introduced. You can see another one of mine Deeply understand the operation principle of blockchain through an App Demo demonstration The code is only the simplest. It simply implements the definition of a block and the connection between blocks. There is no p2p, incentive or consensus.

Important data layer, network layer, consensus layer and incentive layer of blockchain

The following code only shows the above things of the data layer. Later, we will add the rest, study hard and make progress day by day. Come on.

package main

import (

// Convert int to byte array
func Int2Byte(num int64) []byte {
    var buffer bytes.Buffer
    err := binary.Write(&buffer, binary.BigEndian, num)
    return buffer.Bytes()

func CheckErr(err error) {
    if err != nil {
        fmt.Println("err:", err)

//Block structure
type Block struct {
    Version       int64
    PrevBlockHash []byte
    Hash          []byte
    TimeStamp     int64
    TargetBits    int64
    Nonce         int64
    MerkeRoot     []byte
    Data          []byte

func NewBlock(data string, prevBlockHash []byte) *Block {
    block := &Block{
        Version:       1,
        PrevBlockHash: prevBlockHash,
        TimeStamp:     time.Now().Unix(),
        TargetBits:    10,
        Nonce:         5,
        MerkeRoot:     []byte{},
        Data:          []byte(data)}

    return block


// int -> byte

func (block *Block) SetHash() {
    tmp := [][]byte{
        //Function to convert int into byte array
    //Connect block fields into a slice and use [] byte {} to connect

    data := bytes.Join(tmp, []byte{})

    //Calculate the value of hash
    hash := sha256.Sum256(data)
    block.Hash = hash[:]

func NewGenesisBlock() *Block {
    return NewBlock("Genesis Block!", []byte{})

type BlockChian struct {
    //Use slices to save blocks for blockchain simulation
    blocks []*Block

func NewBlockChain() *BlockChian {
    //Create a blockchain
    return &BlockChian{[]*Block{NewGenesisBlock()}}

func (bc *BlockChian) AddBlock(data string) {
    // Block crossing prevention
    if len(bc.blocks) <= 0 {
    lastBlock := bc.blocks[len(bc.blocks)-1]
    block := NewBlock(data, lastBlock.Hash)
    bc.blocks = append(bc.blocks, block)

func main() {
    // Instantiate a blockchain
    bc := NewBlockChain()

    //Add block
    bc.AddBlock("Test the first BTC")
    bc.AddBlock("Test the second EOS")

    //Print out information
    for i, block := range bc.blocks {
        fmt.Println("=========block num:", i)
        fmt.Println("data", string(block.Data))
        fmt.Println("Version:", block.Version)
        fmt.Printf("Hash:%x\n", block.Hash)
        fmt.Printf("TimeStamp:%d\n", block.TimeStamp)
        fmt.Printf("MerkeRoot:%x\n", block.MerkeRoot)
        fmt.Printf("None:%d\n", block.Nonce)

Topics: Blockchain network REST encoding