区块链之挖矿 demo c++实现
在另外一篇博客中，我翻译了区块链Python实现的一个例子。
本篇用C++来实现区块链，不过只是实现了挖矿功能。其它功能，读者可以自行添加。本篇主要讲述一下C++编程实现区块链。
C++的主要特点是面向对象，类，继承等等。另外，使用头文件（*.h).在头文件中定义原型，在c/cpp文件中具体实现。
在本实例中，我们定义Block.h和BlockChain.h俩个头文件。因为要用的加密算法，我们借用网上资源，sha256.cpp和sha256.h俩个文件。主程序是main（）函数。
IDE读者自己选取。本例开发环境是 Ubuntu18+CLion
新建project->DemoChain, 会自动生成main()函数，
#include
int main() {
std::cout << "Hello, World!" << std::endl;
return 0;
}
修改main代码主体如下：
int main() {
//模拟几次挖矿
std::cout << "挖矿1 进行中 。。。" << std::endl;
//挖矿并输出结果
std::cout << "挖矿2 进行中 。。。" << std::endl;
//挖矿并输出结果
std::cout << "挖矿3 进行中 。。。" << std::endl;
//挖矿并输出结果
std::cout << "模拟挖矿结束！" << std::endl;
return 0;
}
然后右键点击项目DemoChain，选择new，选择相应的文件类型，将Block.h, Blockchain.h,Sha256.h和Block.cpp,Blockchain.cpp,Sha256.cpp， 添加文件到项目中。
首先把sha256.h 和 sha256.cpp 从网上粘贴复制到项目中。
sha256.h 如下：
#ifndef DEMOCHAIN_SHA256_H
#define DEMOCHAIN_SHA256_H
#include
class SHA256
{
protected:
typedef unsigned char uint8;
typedef unsigned int uint32;
typedef unsigned long long uint64;
const static uint32 sha256_k[];
static const unsigned int SHA224_256_BLOCK_SIZE = (512/8);
public:
void init();
void update(const unsigned char *message, unsigned int len);
void final(unsigned char *digest);
static const unsigned int DIGEST_SIZE = ( 256 / 8);
protected:
void transform(const unsigned char *message, unsigned int block_nb);
unsigned int m_tot_len;
unsigned int m_len;
unsigned char m_block[2*SHA224_256_BLOCK_SIZE];
uint32 m_h[8];
};
std::string sha256(std::string input);
#define SHA2_SHFR(x, n) (x >> n)
#define SHA2_ROTR(x, n) ((x >> n) | (x << ((sizeof(x) << 3) - n)))
#define SHA2_ROTL(x, n) ((x << n) | (x >> ((sizeof(x) << 3) - n)))
#define SHA2_CH(x, y, z) ((x & y) ^ (~x & z))
#define SHA2_MAJ(x, y, z) ((x & y) ^ (x & z) ^ (y & z))
#define SHA256_F1(x) (SHA2_ROTR(x, 2) ^ SHA2_ROTR(x, 13) ^ SHA2_ROTR(x, 22))
#define SHA256_F2(x) (SHA2_ROTR(x, 6) ^ SHA2_ROTR(x, 11) ^ SHA2_ROTR(x, 25))
#define SHA256_F3(x) (SHA2_ROTR(x, 7) ^ SHA2_ROTR(x, 18) ^ SHA2_SHFR(x, 3))
#define SHA256_F4(x) (SHA2_ROTR(x, 17) ^ SHA2_ROTR(x, 19) ^ SHA2_SHFR(x, 10))
#define SHA2_UNPACK32(x, str) \
{ \
*((str) + 3) = (uint8) ((x) ); \
*((str) + 2) = (uint8) ((x) >> 8); \
*((str) + 1) = (uint8) ((x) >> 16); \
*((str) + 0) = (uint8) ((x) >> 24); \
}
#define SHA2_PACK32(str, x) \
{ \
*(x) = ((uint32) *((str) + 3) ) \
| ((uint32) *((str) + 2) << 8) \
| ((uint32) *((str) + 1) << 16) \
| ((uint32) *((str) + 0) << 24); \
}
#endif //DEMOCHAIN_SHA256_H
sha256.cpp如下：
#include
#include
#include "sha256.h"
const unsigned int SHA256::sha256_k[64] = //UL = uint32
{0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5,
0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3,
0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc,
0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7,
0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13,
0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3,
0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5,
0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208,
0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2};
void SHA256::transform(const unsigned char *message, unsigned int block_nb)
{
uint32 w[64];
uint32 wv[8];
uint32 t1, t2;
const unsigned char *sub_block;
int i;
int j;
for (i = 0; i < (int) block_nb; i++) {
sub_block = message + (i << 6);
for (j = 0; j < 16; j++) {
SHA2_PACK32(&sub_block[j << 2], &w[j]);
}
for (j = 16; j < 64; j++) {
w[j] = SHA256_F4(w[j - 2]) + w[j - 7] + SHA256_F3(w[j - 15]) + w[j - 16];
}
for (j = 0; j < 8; j++) {
wv[j] = m_h[j];
}
for (j = 0; j < 64; j++) {
t1 = wv[7] + SHA256_F2(wv[4]) + SHA2_CH(wv[4], wv[5], wv[6])
+ sha256_k[j] + w[j];
t2 = SHA256_F1(wv[0]) + SHA2_MAJ(wv[0], wv[1], wv[2]);
wv[7] = wv[6];
wv[6] = wv[5];
wv[5] = wv[4];
wv[4] = wv[3] + t1;
wv[3] = wv[2];
wv[2] = wv[1];
wv[1] = wv[0];
wv[0] = t1 + t2;
}
for (j = 0; j < 8; j++) {
m_h[j] += wv[j];
}
}
}
void SHA256::init()
{
m_h[0] = 0x6a09e667;
m_h[1] = 0xbb67ae85;
m_h[2] = 0x3c6ef372;
m_h[3] = 0xa54ff53a;
m_h[4] = 0x510e527f;
m_h[5] = 0x9b05688c;
m_h[6] = 0x1f83d9ab;
m_h[7] = 0x5be0cd19;
m_len = 0;
m_tot_len = 0;
}
void SHA256::update(const unsigned char *message, unsigned int len)
{
unsigned int block_nb;
unsigned int new_len, rem_len, tmp_len;
const unsigned char *shifted_message;
tmp_len = SHA224_256_BLOCK_SIZE - m_len;
rem_len = len < tmp_len ? len : tmp_len;
memcpy(&m_block[m_len], message, rem_len);
if (m_len + len < SHA224_256_BLOCK_SIZE) {
m_len += len;
return;
}
new_len = len - rem_len;
block_nb = new_len / SHA224_256_BLOCK_SIZE;
shifted_message = message + rem_len;
transform(m_block, 1);
transform(shifted_message, block_nb);
rem_len = new_len % SHA224_256_BLOCK_SIZE;
memcpy(m_block, &shifted_message[block_nb << 6], rem_len);
m_len = rem_len;
m_tot_len += (block_nb + 1) << 6;
}
void SHA256::final(unsigned char *digest)
{
unsigned int block_nb;
unsigned int pm_len;
unsigned int len_b;
int i;
block_nb = (1 + ((SHA224_256_BLOCK_SIZE - 9)
< (m_len % SHA224_256_BLOCK_SIZE)));
len_b = (m_tot_len + m_len) << 3;
pm_len = block_nb << 6;
memset(m_block + m_len, 0, pm_len - m_len);
m_block[m_len] = 0x80;
SHA2_UNPACK32(len_b, m_block + pm_len - 4);
transform(m_block, block_nb);
for (i = 0 ; i < 8; i++) {
SHA2_UNPACK32(m_h[i], &digest[i << 2]);
}
}
std::string sha256(std::string input)
{
unsigned char digest[SHA256::DIGEST_SIZE];
memset(digest,0,SHA256::DIGEST_SIZE);
SHA256 ctx = SHA256();
ctx.init();
ctx.update( (unsigned char*)input.c_str(), input.length());
ctx.final(digest);
char buf[2*SHA256::DIGEST_SIZE+1];
buf[2*SHA256::DIGEST_SIZE] = 0;
for (int i = 0; i < SHA256::DIGEST_SIZE; i++)
sprintf(buf+i*2, "%02x", digest[i]);
return std::string(buf);
}
然后我们来具体实现Block.h头文件。还记得块的基本组成吗？
每个块有索引 （index）, 时间戳 （timestamp） , 交易列表（list of transactions）, 证据( proof)和前一个块的哈希（ hash of the previous Block）。除了块的基本组成，我们只添加了一个挖矿功能，MineBlock(uint32_t nDifficulty)，这里挖矿困难度设置为变量参数，根据需要可以调整。
#ifndef DEMOCHAIN_BLOCK_H
#define DEMOCHAIN_BLOCK_H
#include
#include
#include
using namespace std;
class Block {
public:
string sHash;
string sPrevHash;
Block(uint32_t nIndexIn, const string &sDataIn);
void MineBlock(uint32_t nDifficulty);
private:
uint32_t _nIndex;
uint32_t _nNonce;
string _sData;
time_t _tTime;
string _CalculateHash() const;
};
#endif //DEMOCHAIN_BLOCK_H
Block.cpp的具体实现，除了包含Block.h头文件，还包含了sha256.h头文件。
#include "Block.h"
#include "sha256.h"
Block::Block(uint32_t nIndexIn, const string &sDataIn) : _nIndex(nIndexIn), _sData(sDataIn)
{
_nNonce = 0;
_tTime = time(nullptr);
sHash = _CalculateHash();
}
void Block::MineBlock(uint32_t nDifficulty)
{
char cstr[nDifficulty + 1];
for (uint32_t i = 0; i < nDifficulty; ++i)
{
cstr[i] = '0';
}
cstr[nDifficulty] = '\0';
string str(cstr);
do
{
_nNonce++;
sHash = _CalculateHash();
}
while (sHash.substr(0, nDifficulty) != str);
cout << "Block mined: " << sHash << endl;
}
inline string Block::_CalculateHash() const
{
stringstream ss;
ss << _nIndex << sPrevHash << _tTime << _sData << _nNonce;
return sha256(ss.str());
}
基本的Block.h和Block.cpp有了，下面继续来完善Blockchain.h和Blockchain.cpp 文件。
Blockchain 就是一连串的块。Python中用的列表。这里我们用vector
Blockchain.h代码如下：
#ifndef DEMOCHAIN_BLOCKCHAIN_H
#define DEMOCHAIN_BLOCKCHAIN_H
#include
#include
#include "Block.h"
using namespace std;
class Blockchain {
public:
Blockchain();
void AddBlock(Block bNew);
private:
uint32_t _nDifficulty;
vector
Block _GetLastBlock() const;
};
#endif //DEMOCHAIN_BLOCKCHAIN_H
Blockchain.cpp，初始化创世块，将挖矿难度等级设为6， 实现添加块函数的功能，并提供了返回最后一个块的功能。
Blockchain.cpp代码如下：
#include "Blockchain.h"
Blockchain::Blockchain()
{
_vChain.emplace_back(Block(0, "Genesis Block"));
_nDifficulty = 6;
}
void Blockchain::AddBlock(Block bNew)
{
bNew.sPrevHash = _GetLastBlock().sHash;
bNew.MineBlock(_nDifficulty);
_vChain.push_back(bNew);
}
Block Blockchain::_GetLastBlock() const
{
return _vChain.back();
}
我们所需要基本文件都准备好了，最后返回main()函数，实例化Blockchain类，示例挖三次矿，并将结果打印出来。
#include
#include "Blockchain.h"
int main() {
//实例化区块链
Blockchain myChain = Blockchain();
//模拟几次挖矿
std::cout << "挖矿1 进行中 。。。" << std::endl;
//挖矿并输出结果
myChain.AddBlock(Block(1, "块1数据"));
std::cout << "挖矿2 进行中 。。。" << std::endl;
//挖矿并输出结果
myChain.AddBlock(Block(2, "块2数据"));
std::cout << "挖矿3 进行中 。。。" << std::endl;
//挖矿并输出结果
myChain.AddBlock(Block(3, "块3数据"));
std::cout << "模拟挖矿结束！" << std::endl;
return 0;
}
万事俱备，最后就编译运行就可以了。 结果如下：
