生成创世区块并挖矿生成第二个区块

发表于 Valine：

代码

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package main

import (
	"crypto/sha256"
	"encoding/hex"
	"fmt"
	"strconv"
	"time"
)

// Block represents each 'item' in the blockchain
type Block struct {
	Index      int
	Timestamp  string
	Data       string
	Hash       string
	PrevHash   string
	Nonce      int
	Difficulty int
}

// Blockchain is a series of validated Blocks
var Blockchain []Block

// calculateHash is a simple SHA256 hashing function
func calculateHash(block Block) string {
	record := strconv.Itoa(block.Index) + block.Timestamp + block.Data + block.PrevHash + strconv.Itoa(block.Nonce)
	h := sha256.New()
	h.Write([]byte(record))
	hashed := h.Sum(nil)
	return hex.EncodeToString(hashed)
}

// generateBlock creates a new block using previous block's hash
func generateBlock(oldBlock Block, Data string, Difficulty int) Block {
	var newBlock Block

	t := time.Now()

	newBlock.Index = oldBlock.Index + 1
	newBlock.Timestamp = t.String()
	newBlock.Data = Data
	newBlock.PrevHash = oldBlock.Hash
	newBlock.Difficulty = Difficulty
	newBlock.Hash = calculateHash(newBlock)

	// Implement the Proof of Work (PoW)
	for i := 0; ; i++ {
		// hex := fmt.Sprintf("%x", i)
		newBlock.Nonce = i
		if !isHashValid(calculateHash(newBlock), newBlock.Difficulty) {
			fmt.Println(calculateHash(newBlock), " do more work!")
			continue
		} else {
			fmt.Println(calculateHash(newBlock), " work done!")
			newBlock.Hash = calculateHash(newBlock)
			break
		}
	}

	return newBlock
}

// isHashValid checks if the hash meets the criteria defined by difficulty
func isHashValid(hash string, difficulty int) bool {
	prefix := ""
	for i := 0; i < difficulty; i++ {
		prefix += "0"
	}
	return hash[:difficulty] == prefix
}

func main() {
	// Set difficulty
	difficulty := 4

	// Create the genesis block
	t := time.Now()
	genesisBlock := Block{0, t.String(), "Genesis Block", "", "", 0, difficulty}
	genesisBlock.Hash = calculateHash(genesisBlock)
	Blockchain = append(Blockchain, genesisBlock)

	// Add a new block
	newBlock := generateBlock(genesisBlock, "Block #1", difficulty)
	Blockchain = append(Blockchain, newBlock)

	// Print the blockchain
	for _, block := range Blockchain {
		fmt.Printf("Index: %d\n", block.Index)
		fmt.Printf("Timestamp: %s\n", block.Timestamp)
		fmt.Printf("Data: %s\n", block.Data)
		fmt.Printf("Hash: %s\n", block.Hash)
		fmt.Printf("nonce：%d PrevHash: %s\n", block.Nonce, block.PrevHash)
		fmt.Println()
	}
}