使用Windows CryptoAPI计算MD5

使用Windows CryptoAPI计算MD5

2012年7月7日代码疯子发表评论阅读评论

About Windows CryptoAPI: Application programming interface that enables application developers to add authentication, encoding, and encryption to Windows-based applications.

直接使用Windows提供的CryptAcquireContext、CryptCreateHash、CryptHashData、CryptGetHashParam等API就可以计算MD5了，稍微封装了一下，可以算文件或者字符串的MD5值，文件传入UNICODE类型字符串的路径，字符串使用普通的CHAR，因为UNICODE和非UNICODE算出来的MD5不一样（字符串看上去一样，实际的BYTE不一样）。





计算MD5的测试代码如下：

// Author: 代码疯子
// Blog: http://www.programlife.net/ #include <stdio.h>
#include <windows.h>
#include <Wincrypt.h>

#define CHECK_NULL_RET(bCondition) if (!bCondition) goto Exit0
#define BUFSIZE 1024
#define MD5LEN  16

BOOL GetContentMD5(
BYTE *pszFilePath,
BOOL bFile,
BOOL bUpperCase,
TCHAR *pszResult,
DWORD &dwStatus)
{
BOOL bResult = FALSE;
HCRYPTPROV hProv = 0;
HCRYPTHASH hHash = 0;
HANDLE hFile = NULL;
BYTE rgbFile[BUFSIZE];
DWORD cbRead = 0;
BYTE rgbHash[MD5LEN];
DWORD cbHash = 0;
CHAR rgbDigitsL[] = "0123456789abcdef";
CHAR rgbDigitsU[] = "0123456789ABCDEF";
CHAR *rgbDigits = bUpperCase ? rgbDigitsU : rgbDigitsL;
TCHAR szResult[MD5LEN*2+1] = {0};

dwStatus = 0;
bResult = CryptAcquireContext(&hProv,
NULL,
NULL,
PROV_RSA_FULL,
CRYPT_VERIFYCONTEXT);
CHECK_NULL_RET(bResult);

bResult = CryptCreateHash(hProv, CALG_MD5, 0, 0, &hHash);
CHECK_NULL_RET(bResult);

if (bFile)
{
hFile = CreateFile((TCHAR *)pszFilePath,
GENERIC_READ,
FILE_SHARE_READ,
NULL,
OPEN_EXISTING,
FILE_FLAG_SEQUENTIAL_SCAN,
NULL);
CHECK_NULL_RET(!(INVALID_HANDLE_VALUE == hFile));

while (bResult = ReadFile(hFile, rgbFile, BUFSIZE,
&cbRead, NULL))
{
if (0 == cbRead)
{
break;
}

bResult = CryptHashData(hHash, rgbFile, cbRead, 0);
CHECK_NULL_RET(bResult);
}
}
else
{
bResult = CryptHashData(hHash, pszFilePath, strlen((CHAR *)pszFilePath), 0);
CHECK_NULL_RET(bResult);
}

cbHash = MD5LEN;
if (bResult = CryptGetHashParam(hHash, HP_HASHVAL, rgbHash, &cbHash, 0))
{
TCHAR szTmpBuff[3] = {0};
for (DWORD i = 0; i < cbHash; i++)
{
swprintf(szTmpBuff, TEXT("%c%c"), rgbDigits[rgbHash[i] >> 4],
rgbDigits[rgbHash[i] & 0xf]);
lstrcat(szResult, szTmpBuff);
}
bResult = TRUE;
}

Exit0:
dwStatus = GetLastError();
CryptDestroyHash(hHash);
CryptReleaseContext(hProv, 0);
CloseHandle(hFile);

lstrcpy(pszResult, szResult);

return bResult;
}

int main(int argc, char* argv[])
{
DWORD dwStatus = 0;
TCHAR szResult[MD5LEN*2+1] = {0};
TCHAR szFilePath[] = TEXT("C:\\Windows\\System32\\notepad.exe");
CHAR szContent[] = "explorer.exe";

GetContentMD5((BYTE *)szFilePath,
TRUE, TRUE, szResult, dwStatus);
MessageBox(NULL, szResult, TEXT("MD5"), MB_OK);

GetContentMD5((BYTE *)szContent, FALSE, TRUE, szResult, dwStatus);
MessageBox(NULL, szResult, TEXT("MD5"), MB_OK);

return 0;
}

// explorer.exe的MD5为CDE09BCDF5FDE1E2EAC52C0F93362B79

参考：Example C Program:
Creating an MD5 Hash from File Content