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实验报告05orz
实验目的及要求实验基本原理实验实施环境实验概述实验内容学习第五章 区块链挖矿交易实现区块链挖矿交易的代码编写项目目录截图原型代码Terminal运行结果截图
论述挖矿算法的使用意义
实验目的及要求
了解编程语言的基本逻辑，理解编程语言运行机理。熟悉区块链的原理。能正确使用编程语言搭建区块和区块链，并进行工作量证明实现。
实验基本原理
通过课堂理论教学准备，动手使用实验软件平台，完成慕课实验项目的要求。
实验实施环境
Goland & GoSDK
实验概述
编写区块链基本原型，加入挖矿交易详细算法。
实验内容
学习第五章 区块链挖矿交易
imooc学习地址↓ 5-3挖矿流程及代码实现 5-4交易记账流程及代码实现 学习总结： 区块链的交易机制如下图：  te代表每个交易，其中没被箭头连接到的output代表涉及到交易的账户余额。
实现区块链挖矿交易的代码编写
项目目录截图
原型代码
main.go
/*
* @Author: Chen Shan
* @Date: 2020/10/19 09:48
*/
package main
import (
"core"
)
func main() {
cli := core.CLI{}
cli.Run()
}
block.go
/*
* @Author: Chen Shan
* @Date: 2020/10/19 09:48
*/
package core
import (
"bytes"
"crypto/sha256"
"encoding/gob"
"log"
"time"
)
// 时间戳
// 交易
// 前一个块哈希
// 当前块哈希
// 难度值
type Block struct {
Timestamp int64
Transactions []*Transaction
PrevBlockHash []byte
Hash []byte
Nonce int
}
func (b *Block) Serialize() []byte {
var result bytes.Buffer
encoder := gob.NewEncoder(&result)
err := encoder.Encode(b)
if err != nil {
log.Panic(err)
}
return result.Bytes()
}
// Deserialize a block
func DeserializeBlock(d []byte) *Block {
var block Block
decoder := gob.NewDecoder(bytes.NewReader(d))
err := decoder.Decode(&block)
if err != nil {
log.Panic(err)
}
return &block
}
// NewBlock creates and returns Block
func NewBlock(transactions []*Transaction, prevBlockHash []byte) *Block {
block := &Block{
Timestamp: time.Now().Unix(),
Transactions: transactions,
PrevBlockHash: prevBlockHash,
Hash: []byte{},
Nonce: 0}
pow := NewProofOfWork(block)
nonce, hash := pow.Run()
block.Hash = hash[:]
block.Nonce = nonce
return block
}
// NewGenesisBlock creates and returns Genesis Block
func NewGenesisBlock(coinbase *Transaction) *Block {
return NewBlock([]*Transaction{coinbase}, []byte{})
}
// 计算区块里所有交易的哈希
func (b *Block) HashTransactions() []byte {
var txHashes [][]byte
var txHash [32]byte
for _, tx := range b.Transactions {
txHashes = append(txHashes, tx.ID)
}
txHash = sha256.Sum256(bytes.Join(txHashes, []byte{}))
return txHash[:]
}
blockchain.go
/*
* @Author: Chen Shan
* @Date: 2020/10/19 09:49
*/
package core
import (
"encoding/hex"
"fmt"
"log"
"os"
"github.com/boltdb/bolt"
)
const dbFile = "blockchain.db"
const blocksBucket = "blocks"
const genesisCoinbaseData = "The Times 03/Jan/2009 Chancellor on brink of second bailout for banks"
type Blockchain struct {
tip []byte
db *bolt.DB
}
type BlockchainIterator struct {
currentHash []byte
db *bolt.DB
}
func (bc *Blockchain) MineBlock(transactions []*Transaction) {
var lastHash []byte
err := bc.db.View(func(tx *bolt.Tx) error {
b := tx.Bucket([]byte(blocksBucket))
lastHash = b.Get([]byte("l"))
return nil
})
if err != nil {
log.Panic(err)
}
newBlock := NewBlock(transactions, lastHash)
err = bc.db.Update(func(tx *bolt.Tx) error {
b := tx.Bucket([]byte(blocksBucket))
err := b.Put(newBlock.Hash, newBlock.Serialize())
if err != nil {
log.Panic(err)
}
err = b.Put([]byte("l"), newBlock.Hash)
if err != nil {
log.Panic(err)
}
bc.tip = newBlock.Hash
return nil
})
}
func (bc *Blockchain) Iterator() *BlockchainIterator {
bci := &BlockchainIterator{bc.tip, bc.db}
return bci
}
func (i *BlockchainIterator) Next() *Block {
var block *Block
err := i.db.View(func(tx *bolt.Tx) error {
b := tx.Bucket([]byte(blocksBucket))
encodedBlock := b.Get(i.currentHash)
block = DeserializeBlock(encodedBlock)
return nil
})
if err != nil {
log.Panic(err)
}
i.currentHash = block.PrevBlockHash
return block
}
func dbExists() bool {
if _, err := os.Stat(dbFile); os.IsNotExist(err) {
return false
}
return true
}
// 创建一个有创世块的新链
func NewBlockchain(address string) *Blockchain {
if dbExists() == false {
fmt.Println("No existing blockchain found. Create one first.")
os.Exit(1)
}
var tip []byte
db, err := bolt.Open(dbFile, 0600, nil)
if err != nil {
log.Panic(err)
}
err = db.Update(func(tx *bolt.Tx) error {
b := tx.Bucket([]byte(blocksBucket))
tip = b.Get([]byte("l"))
return nil
})
if err != nil {
log.Panic(err)
}
bc := Blockchain{tip, db}
return &bc
}
// CreateBlockchain 创建一个新的区块链数据库
// address 用来接收挖出创世块的奖励
func CreateBlockchain(address string) *Blockchain {
if dbExists() {
fmt.Println("Blockchain already exists.")
os.Exit(1)
}
var tip []byte
db, err := bolt.Open(dbFile, 0600, nil)
if err != nil {
log.Panic(err)
}
err = db.Update(func(tx *bolt.Tx) error {
cbtx := NewCoinbaseTX(address, genesisCoinbaseData)
genesis := NewGenesisBlock(cbtx)
b, err := tx.CreateBucket([]byte(blocksBucket))
if err != nil {
log.Panic(err)
}
err = b.Put(genesis.Hash, genesis.Serialize())
if err != nil {
log.Panic(err)
}
err = b.Put([]byte("l"), genesis.Hash)
if err != nil {
log.Panic(err)
}
tip = genesis.Hash
return nil
})
if err != nil {
log.Panic(err)
}
bc := Blockchain{tip, db}
return &bc
}
// FindUnspentTransactions 找到未花费输出的交易
func (bc *Blockchain) FindUnspentTransactions(address string) []Transaction {
var unspentTXs []Transaction
spentTXOs := make(map[string][]int)
bci := bc.Iterator()
for {
block := bci.Next()
for _, tx := range block.Transactions {
txID := hex.EncodeToString(tx.ID)
Outputs:
for outIdx, out := range tx.Vout {
// 如果交易输出被花费了
if spentTXOs[txID] != nil {
for _, spentOut := range spentTXOs[txID] {
if spentOut == outIdx {
continue Outputs
}
}
}
// 如果该交易输出可以被解锁，即可被花费
if out.CanBeUnlockedWith(address) {
unspentTXs = append(unspentTXs, *tx)
}
}
if tx.IsCoinbase() == false {
for _, in := range tx.Vin {
if in.CanUnlockOutputWith(address) {
inTxID := hex.EncodeToString(in.Txid)
spentTXOs[inTxID] = append(spentTXOs[inTxID], in.Vout)
}
}
}
}
if len(block.PrevBlockHash) == 0 {
break
}
}
return unspentTXs
}
func (bc *Blockchain) FindUTXO(address string) []TXOutput {
var UTXOs []TXOutput
unspentTransactions := bc.FindUnspentTransactions(address)
for _, tx := range unspentTransactions {
for _, out := range tx.Vout {
if out.CanBeUnlockedWith(address) {
UTXOs = append(UTXOs, out)
}
}
}
return UTXOs
}
// FindSpendableOutputs 从 address 中找到至少 amount 的 UTXO
func (bc *Blockchain) FindSpendableOutputs(address string, amount int) (int, map[string][]int) {
unspentOutputs := make(map[string][]int)
unspentTXs := bc.FindUnspentTransactions(address)
accumulated := 0
Work:
for _, tx := range unspentTXs {
txID := hex.EncodeToString(tx.ID)
for outIdx, out := range tx.Vout {
if out.CanBeUnlockedWith(address) && accumulated
break Work
}
}
}
}
return accumulated, unspentOutputs
}
cil.go
/*
* @Author: Chen Shan
* @Date: 2020/10/19 09:49
*/
package core
import (
"flag"
"fmt"
"log"
"os"
"strconv"
)
type CLI struct{}
func (cli *CLI) createBlockchain(address string) {
bc := CreateBlockchain(address)
bc.db.Close()
fmt.Println("Done!")
}
func (cli *CLI) getBalance(address string) {
bc := NewBlockchain(address)
defer bc.db.Close()
balance := 0
UTXOs := bc.FindUTXO(address)
for _, out := range UTXOs {
balance += out.Value
}
fmt.Printf("Balance of '%s': %d\n", address, balance)
}
func (cli *CLI) printUsage() {
fmt.Println("Usage:")
fmt.Println(" getbalance -address ADDRESS - Get balance of ADDRESS")
fmt.Println(" createblockchain -address ADDRESS - Create a blockchain and send genesis block reward to ADDRESS")
fmt.Println(" printchain - Print all the blocks of the blockchain")
fmt.Println(" send -from FROM -to TO -amount AMOUNT - Send AMOUNT of coins from FROM address to TO")
}
func (cli *CLI) validateArgs() {
if len(os.Args)
bc := NewBlockchain("")
defer bc.db.Close()
bci := bc.Iterator()
for {
block := bci.Next()
fmt.Printf("Prev hash: %x\n", block.PrevBlockHash)
fmt.Printf("Hash: %x\n", block.Hash)
pow := NewProofOfWork(block)
fmt.Printf("PoW: %s\n", strconv.FormatBool(pow.Validate()))
fmt.Println()
if len(block.PrevBlockHash) == 0 {
break
}
}
}
func (cli *CLI) send(from, to string, amount int) {
bc := NewBlockchain(from)
defer bc.db.Close()
tx := NewUTXOTransaction(from, to, amount, bc)
bc.MineBlock([]*Transaction{tx})
fmt.Println("Success!")
}
func (cli *CLI) Run() {
cli.validateArgs()
getBalanceCmd := flag.NewFlagSet("getbalance", flag.ExitOnError)
createBlockchainCmd := flag.NewFlagSet("createblockchain", flag.ExitOnError)
sendCmd := flag.NewFlagSet("send", flag.ExitOnError)
printChainCmd := flag.NewFlagSet("printchain", flag.ExitOnError)
getBalanceAddress := getBalanceCmd.String("address", "", "The address to get balance for")
createBlockchainAddress := createBlockchainCmd.String("address", "", "The address to send genesis block reward to")
sendFrom := sendCmd.String("from", "", "Source wallet address")
sendTo := sendCmd.String("to", "", "Destination wallet address")
sendAmount := sendCmd.Int("amount", 0, "Amount to send")
switch os.Args[1] {
case "getbalance":
err := getBalanceCmd.Parse(os.Args[2:])
if err != nil {
log.Panic(err)
}
case "createblockchain":
err := createBlockchainCmd.Parse(os.Args[2:])
if err != nil {
log.Panic(err)
}
case "send":
err := sendCmd.Parse(os.Args[2:])
if err != nil {
log.Panic(err)
}
case "printchain":
err := printChainCmd.Parse(os.Args[2:])
if err != nil {
log.Panic(err)
}
default:
cli.printUsage()
os.Exit(1)
}
if getBalanceCmd.Parsed() {
if *getBalanceAddress == "" {
getBalanceCmd.Usage()
os.Exit(1)
}
cli.getBalance(*getBalanceAddress)
}
if createBlockchainCmd.Parsed() {
if *createBlockchainAddress == "" {
createBlockchainCmd.Usage()
os.Exit(1)
}
cli.createBlockchain(*createBlockchainAddress)
}
if printChainCmd.Parsed() {
cli.printChain()
}
if sendCmd.Parsed() {
if *sendFrom == "" || *sendTo == "" || *sendAmount
block *Block
target *big.Int
}
func NewProofOfWork(b *Block) *ProofOfWork {
target := big.NewInt(1)
target.Lsh(target, uint(256-targetBits))
pow := &ProofOfWork{b, target}
return pow
}
func (pow *ProofOfWork) prepareData(nonce int) []byte {
data := bytes.Join(
[][]byte{
pow.block.PrevBlockHash,
pow.block.HashTransactions(),
IntToHex(pow.block.Timestamp),
IntToHex(int64(targetBits)),
IntToHex(int64(nonce)),
},
[]byte{},
)
return data
}
func (pow *ProofOfWork) Run() (int, []byte) {
var hashInt big.Int
var hash [32]byte
nonce := 0
fmt.Printf("Mining a new block")
for nonce
break
} else {
nonce++
}
}
fmt.Print("\n\n")
return nonce, hash[:]
}
// Validate block's PoW
func (pow *ProofOfWork) Validate() bool {
var hashInt big.Int
data := pow.prepareData(pow.block.Nonce)
hash := sha256.Sum256(data)
hashInt.SetBytes(hash[:])
isValid := hashInt.Cmp(pow.target) == -1
return isValid
}
transaction.go
/*
* @Author: Chen Shan
* @Date: 2020/10/19 09:49
*/
package core
import (
"bytes"
"crypto/sha256"
"encoding/gob"
"encoding/hex"
"fmt"
"log"
)
const subsidy = 10
// Transaction 由交易 ID，输入和输出构成
type Transaction struct {
ID []byte
Vin []TXInput
Vout []TXOutput
}
// TXInput 包含 3 部分
// Txid: 一个交易输入引用了之前一笔交易的一个输出, ID 表明是之前哪笔交易
// Vout: 一笔交易可能有多个输出，Vout 为输出的索引
// ScriptSig: 提供解锁输出 Txid:Vout 的数据
type TXInput struct {
Txid []byte
Vout int
ScriptSig string
}
// TXOutput 包含两部分
// Value: 有多少币，就是存储在 Value 里面
// ScriptPubKey: 对输出进行锁定
// 在当前实现中，ScriptPubKey 将仅用一个字符串来代替
type TXOutput struct {
Value int
ScriptPubKey string
}
// IsCoinbase 判断是否是 coinbase 交易
func (tx Transaction) IsCoinbase() bool {
return len(tx.Vin) == 1 && len(tx.Vin[0].Txid) == 0 && tx.Vin[0].Vout == -1
}
func (tx *Transaction) SetID() {
var encoded bytes.Buffer
var hash [32]byte
enc := gob.NewEncoder(&encoded)
err := enc.Encode(tx)
if err != nil {
log.Panic(err)
}
hash = sha256.Sum256(encoded.Bytes())
tx.ID = hash[:]
}
// 这里的 unlockingData 可以理解为地址
func (in *TXInput) CanUnlockOutputWith(unlockingData string) bool {
return in.ScriptSig == unlockingData
}
func (out *TXOutput) CanBeUnlockedWith(unlockingData string) bool {
return out.ScriptPubKey == unlockingData
}
// NewCoinbaseTX 构建 coinbase 交易，该没有输入，只有一个输出
func NewCoinbaseTX(to, data string) *Transaction {
if data == "" {
data = fmt.Sprintf("Reward to '%s'", to)
}
txin := TXInput{[]byte{}, -1, data}
txout := TXOutput{subsidy, to}
tx := Transaction{nil, []TXInput{txin}, []TXOutput{txout}}
tx.SetID()
return &tx
}
// NewUTXOTransaction 创建一笔新的交易
func NewUTXOTransaction(from, to string, amount int, bc *Blockchain) *Transaction {
var inputs []TXInput
var outputs []TXOutput
// 找到足够的未花费输出
acc, validOutputs := bc.FindSpendableOutputs(from, amount)
if acc
txID, err := hex.DecodeString(txid)
if err != nil {
log.Panic(err)
}
for _, out := range outs {
input := TXInput{txID, out, from}
inputs = append(inputs, input)
}
}
outputs = append(outputs, TXOutput{amount, to})
// 如果 UTXO 总数超过所需，则产生找零
if acc > amount {
outputs = append(outputs, TXOutput{acc - amount, from})
}
tx := Transaction{nil, inputs, outputs}
tx.SetID()
return &tx
}
utils.go
/*
* @Author: Chen Shan
* @Date: 2020/10/19 09:49
*/
package core
import (
"bytes"
"encoding/binary"
"log"
)
// Convert an int64 to a byte array
func IntToHex(num int64) []byte {
buff := new(bytes.Buffer)
err := binary.Write(buff, binary.BigEndian, num)
if err != nil {
log.Panic(err)
}
return buff.Bytes()
}
Terminal运行结果截图
 
论述挖矿算法的使用意义
就不告诉你~
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