C++/python求哈希值(SHA256)

发现一个很奇怪的现象：

python语言求哈希值所用时间竟然比C++少：

C++ code

#include "stdafx.h"
#include <windows.h>
#include <time.h>
#include <iostream>
void ShowError(char *pszText)
{
    char szErr[MAX_PATH] = { 0 };
    ::sprintf_s(szErr, "%s Error[%d]
", pszText, ::GetLastError());
#ifdef _DEBUG
    // required size
    int size = MultiByteToWideChar(CP_UTF8, 0, szErr, -1, NULL, 0);
    wchar_t *pwcsName = new wchar_t[size];
    MultiByteToWideChar(CP_UTF8, 0, szErr, -1, (LPWSTR)pwcsName, size);
    ::MessageBox(NULL, pwcsName, L"ERROR", MB_OK | MB_ICONERROR);
    delete[] pwcsName;
#endif
}


BOOL GetFileData(char *pszFilePath, BYTE **ppFileData, DWORD *pdwFileDataLength)
{
    BOOL bRet = TRUE;
    BYTE *pFileData = NULL;
    DWORD dwFileDataLength = 0;
    HANDLE hFile = NULL;
    DWORD dwTemp = 0;

    do
    {
        // required size
        int size = MultiByteToWideChar(CP_UTF8, 0, pszFilePath, -1, NULL, 0);
        wchar_t *pwcsName = new wchar_t[size];
        MultiByteToWideChar(CP_UTF8, 0, pszFilePath, -1, (LPWSTR)pwcsName, size);
        hFile = ::CreateFile(pwcsName, GENERIC_READ | GENERIC_WRITE,
            FILE_SHARE_READ | FILE_SHARE_WRITE, NULL, OPEN_EXISTING,
            FILE_ATTRIBUTE_ARCHIVE, NULL);
        delete[] pwcsName;
        if (INVALID_HANDLE_VALUE == hFile)
        {
            bRet = FALSE;
            ShowError("CreateFile");
            break;
        }

        dwFileDataLength = ::GetFileSize(hFile, NULL);

        pFileData = new BYTE[dwFileDataLength];
        if (NULL == pFileData)
        {
            bRet = FALSE;
            ShowError("new");
            break;
        }
        ::RtlZeroMemory(pFileData, dwFileDataLength);

        ::ReadFile(hFile, pFileData, dwFileDataLength, &dwTemp, NULL);

        // 返回
        *ppFileData = pFileData;
        *pdwFileDataLength = dwFileDataLength;

    } while (FALSE);

    if (hFile)
    {
        ::CloseHandle(hFile);
    }

    return bRet;
}


BOOL CalculateHash(BYTE *pData, DWORD dwDataLength, ALG_ID algHashType, BYTE **ppHashData, DWORD *pdwHashDataLength)
{
    HCRYPTPROV hCryptProv = NULL;
    HCRYPTHASH hCryptHash = NULL;
    BYTE *pHashData = NULL;
    DWORD dwHashDataLength = 0;
    DWORD dwTemp = 0;
    BOOL bRet = FALSE;


    do
    {
        // 获得指定CSP的密钥容器的句柄
        bRet = ::CryptAcquireContext(&hCryptProv, NULL, NULL, PROV_RSA_AES, CRYPT_VERIFYCONTEXT);
        if (FALSE == bRet)
        {
            ShowError("CryptAcquireContext");
            break;
        }

        // 创建一个HASH对象, 指定HASH算法
        bRet = ::CryptCreateHash(hCryptProv, algHashType, NULL, NULL, &hCryptHash);
        if (FALSE == bRet)
        {
            ShowError("CryptCreateHash");
            break;
        }

        // 计算HASH数据
        bRet = ::CryptHashData(hCryptHash, pData, dwDataLength, 0);
        if (FALSE == bRet)
        {
            ShowError("CryptHashData");
            break;
        }

        // 获取HASH结果的大小
        dwTemp = sizeof(dwHashDataLength);
        bRet = ::CryptGetHashParam(hCryptHash, HP_HASHSIZE, (BYTE *)(&dwHashDataLength), &dwTemp, 0);
        if (FALSE == bRet)
        {
            ShowError("CryptGetHashParam");
            break;
        }

        // 申请内存
        pHashData = new BYTE[dwHashDataLength];
        if (NULL == pHashData)
        {
            bRet = FALSE;
            ShowError("new");
            break;
        }
        ::RtlZeroMemory(pHashData, dwHashDataLength);

        // 获取HASH结果数据
        bRet = ::CryptGetHashParam(hCryptHash, HP_HASHVAL, pHashData, &dwHashDataLength, 0);
        if (FALSE == bRet)
        {
            ShowError("CryptGetHashParam");
            break;
        }

        // 返回数据
        *ppHashData = pHashData;
        *pdwHashDataLength = dwHashDataLength;

    } while (FALSE);

    // 释放关闭
    if (FALSE == bRet)
    {
        if (pHashData)
        {
            delete[]pHashData;
            pHashData = NULL;
        }
    }
    if (hCryptHash)
    {
        ::CryptDestroyHash(hCryptHash);
    }
    if (hCryptProv)
    {
        ::CryptReleaseContext(hCryptProv, 0);
    }

    return bRet;
}


int _tmain(int argc, _TCHAR* argv[])
{
    BYTE *pData = NULL;
    DWORD dwDataLength = 0;
    DWORD i = 0;
    BYTE *pHashData = NULL;
    DWORD dwHashDataLength = 0;

    // 读取文件数据
    GetFileData("C:\Users\Administrator\Desktop\paraseLED\white\process.exe", &pData, &dwDataLength);

    // MD5
    CalculateHash(pData, dwDataLength, CALG_MD5, &pHashData, &dwHashDataLength);
    printf("MD5[%d]
", dwHashDataLength);
    for (i = 0; i < dwHashDataLength; i++)
    {
        printf("%x", pHashData[i]);
    }
    printf("

");
    if (pHashData)
    {
        delete[]pHashData;
        pHashData = NULL;
    }

    // SHA1
    CalculateHash(pData, dwDataLength, CALG_SHA1, &pHashData, &dwHashDataLength);
    printf("SHA1[%d]
", dwHashDataLength);
    std::string hash_ = "";
    for (i = 0; i < dwHashDataLength; i++)
    {
        char temp[32] = { 0 };
        sprintf_s(temp, "%x", pHashData[i]);
        hash_.append(temp);
        printf("%x", pHashData[i]);
    }
    printf("

");
    std::cout << hash_.c_str() << std::endl;
    printf("

");
    if (pHashData)
    {
        delete[]pHashData;
        pHashData = NULL;
    }

    // SHA256
    clock_t start, end;
    start = clock();
    CalculateHash(pData, dwDataLength, CALG_SHA_256, &pHashData, &dwHashDataLength);
    printf("SHA256[%d]
", dwHashDataLength);
    for (i = 0; i < dwHashDataLength; i++)
    {
        printf("%x", pHashData[i]);
    }
    end = clock();
    printf("

");
    printf("timestamp = %f
", double(end - start) / CLOCKS_PER_SEC);
    if (pHashData)
    {
        delete[]pHashData;
        pHashData = NULL;
    }

    system("pause");
    return 0;
}

python code

# Python program to find SHA256 hexadecimal hash string of a file
import hashlib
import time
 
start = time.time()
filename = r'C:UsersAdministratorDesktopparaseLEDwhiteprocess.exe'
with open(filename,"rb") as f:
    bytes = f.read() # read entire file as bytes
    readable_hash = hashlib.sha256(bytes).hexdigest();
    print(readable_hash)
end = time.time()
print('timestamp = {}'.format(end - start))