hash.cpp

Go to the documentation of this file.

#include "hash.h"
#include <wincrypt.h>
 
std::string GenerateMD5(std::string filePath)
{
    if (filePath.empty())
    {
        return "";
    }
    WCHAR fileHash[33];
    HANDLE hFile = CreateFileA(filePath.c_str(), GENERIC_READ, FILE_SHARE_READ, NULL, OPEN_EXISTING, FILE_FLAG_SEQUENTIAL_SCAN, NULL);
    if (hFile == INVALID_HANDLE_VALUE) {
        return "";
    }
 
    HCRYPTPROV hProv = 0;
    HCRYPTHASH hHash = 0;
    BYTE rgbHash[16];
    DWORD cbHash = 0;
    WCHAR rgbDigits[] = L"0123456789abcdef";
 
    if (!CryptAcquireContext(&hProv, NULL, NULL, PROV_RSA_FULL, CRYPT_VERIFYCONTEXT) ||
        !CryptCreateHash(hProv, CALG_MD5, 0, 0, &hHash)) {
        CloseHandle(hFile);
        return "";
    }
 
    BYTE rgbFile[1024];
    DWORD bytesRead = 0;
    while (ReadFile(hFile, rgbFile, sizeof(rgbFile), &bytesRead, NULL)) {
        if (bytesRead == 0) break;
        if (!CryptHashData(hHash, rgbFile, bytesRead, 0)) {
            CryptReleaseContext(hProv, 0);
            CryptDestroyHash(hHash);
            CloseHandle(hFile);
            return "";
        }
    }
 
    cbHash = 16;
    if (CryptGetHashParam(hHash, HP_HASHVAL, rgbHash, &cbHash, 0)) {
        for (DWORD i = 0; i < cbHash; i++) {
            fileHash[i * 2] = rgbDigits[rgbHash[i] >> 4];
            fileHash[i * 2 + 1] = rgbDigits[rgbHash[i] & 0xf];
        }
        fileHash[32] = L'\0';
    }
 
    int size_needed = WideCharToMultiByte(CP_UTF8, 0, fileHash, -1, NULL, 0, NULL, NULL);
    std::string result(size_needed, 0);
    WideCharToMultiByte(CP_UTF8, 0, fileHash, -1, &result[0], size_needed, NULL, NULL);
    std::string test = std::string(result.begin(), result.end());
    CryptReleaseContext(hProv, 0);
    CryptDestroyHash(hHash);
    CloseHandle(hFile);
    return result;
}