GPU支持大规模的并行加速运算,胜在量上,CPU处理大量的并行运算显得力不从心,它是胜在逻辑上。利用显卡加速的应用越来越多,但如果说GPU即将或最终将替代CPU还有点言过其实,二者最终将优势互补,各尽所能。
使用显卡的无脑并行运算破解密码是一个不错的选择。这里选择一种简单的情况,限定密码是6位纯数字,并且不限定输入次数,这种 情况下可以使用GPU暴力破解,当然仅供娱乐,并无任何实际的应用价值。
#include "cuda_runtime.h"
#include "device_launch_parameters.h"
#include <stdio.h>
#include <iostream>
#include "time.h"
using namespace std;
//密码破解入口函数
cudaError_t BreakWithCuda(const int *userKeyWord, int *keyWordByGPU);
//密码破解核函数
__global__ void BreakPasswordKernel(const int *userKeyWord, int *keyWordByGPU)
{
//获取线程的索引号
int blockId = blockIdx.y*gridDim.x + blockIdx.x;
int threadID = blockId*blockDim.x + threadIdx.x;
if (threadID == *userKeyWord)
{
*keyWordByGPU = threadID;
}
}
int main()
{
int userWord = 0; //用户输入的密码
int keyWordByGPU = 0; //接收GPU破解的密码
cout << "请输入你设置的密码(6位阿拉伯数字):" << endl;
cin >> userWord;
const int keyWord = userWord;
getchar();
//计算耗时变量
clock_t startTime, endTime;
startTime = clock();
cudaError_t cudaStatus = BreakWithCuda(&keyWord, &keyWordByGPU);
if (cudaStatus != cudaSuccess) {
fprintf(stderr, "BreakWithCuda failed!");
return 1;
}
//重置GPU设备
cudaStatus = cudaDeviceReset();
if (cudaStatus != cudaSuccess) {
fprintf(stderr, "cudaDeviceReset failed!");
return 1;
}
cout << "
经GPU运算破解的用户密码是:" << endl;
//输出破解的密码,不足6位前补0
cout.fill('0');
cout.width(6); //总长度6位
cout << keyWordByGPU << endl << endl;
endTime = clock(); //破解耗时,以秒位单位
float spendTime = (float)(endTime - startTime) / CLOCKS_PER_SEC;
cout << "耗时:
" << spendTime << "seconds" << endl;
getchar();
return 0;
}
cudaError_t BreakWithCuda(const int *userKeyword, int *keyWordByGPU)
{
int *dev_userKeyWord = 0;
int *dev_keyWordByGPU = 0;
cudaError_t cudaStatus;
//选择运行设备
cudaStatus = cudaSetDevice(0);
if (cudaStatus != cudaSuccess) {
fprintf(stderr, "cudaSetDevice failed! Do you have a CUDA-capable GPU installed?");
goto Error;
}
// 在GUP上分配显存
cudaStatus = cudaMalloc((void**)&dev_userKeyWord, sizeof(int));
if (cudaStatus != cudaSuccess) {
fprintf(stderr, "cudaMalloc failed!");
goto Error;
}
cudaStatus = cudaMalloc((void**)&dev_keyWordByGPU, sizeof(int));
if (cudaStatus != cudaSuccess) {
fprintf(stderr, "cudaMalloc failed!");
goto Error;
}
// 把用户输入的密码从主机复制到设备显存上
cudaStatus = cudaMemcpy(dev_userKeyWord, userKeyword, sizeof(int), cudaMemcpyHostToDevice);
if (cudaStatus != cudaSuccess) {
fprintf(stderr, "cudaMemcpy failed!");
goto Error;
}
dim3 grid(100, 100); //创建一个包含100*100个线程块的Grid
BreakPasswordKernel << <grid, 100 >> > (dev_userKeyWord, dev_keyWordByGPU);
// GPU运行错误检查
cudaStatus = cudaGetLastError();
if (cudaStatus != cudaSuccess) {
fprintf(stderr, "BreakPasswordKernel launch failed: %s
", cudaGetErrorString(cudaStatus));
goto Error;
}
// cudaDeviceSynchronize waits for the kernel to finish, and returns
// any errors encountered during the launch.
cudaStatus = cudaDeviceSynchronize();
if (cudaStatus != cudaSuccess) {
fprintf(stderr, "cudaDeviceSynchronize returned error code %d after launching BreakPasswordKernel!
", cudaStatus);
goto Error;
}
// 把破解的密码从GPU拷贝到CPU
cudaStatus = cudaMemcpy(keyWordByGPU, dev_keyWordByGPU, sizeof(int), cudaMemcpyDeviceToHost);
if (cudaStatus != cudaSuccess) {
fprintf(stderr, "cudaMemcpy failed!");
goto Error;
}
Error:
cudaFree(dev_keyWordByGPU);
cudaFree(dev_userKeyWord);
return cudaStatus;
}
输入的密码第一位或之后若干位为0的情况:
正常情况: