#include <windows.h>
#include <tchar.h>

//计算MD5，成功返回0，失败返回GetLastError()
DWORD MD5(__in_bcount(dwDataLen) const LPVOID pData, // 输入数据 
		  __in DWORD dwDataLen, // 输入数据字节长度 
		  __out LPTSTR pszMD5, // 输出字符串，TCHAR长度必须大于等于33 
		  __in BOOL bCap = FALSE) // 是否输出为大写 
{
	DWORD dwReturn = 0;
	HCRYPTPROV hProv;
	if (!CryptAcquireContext(&hProv, NULL, NULL, PROV_RSA_FULL, CRYPT_VERIFYCONTEXT))
		return (dwReturn = GetLastError());

	HCRYPTHASH hHash;
	if (!CryptCreateHash(hProv, CALG_MD5, 0, 0, &hHash))
	{
		dwReturn = GetLastError();
		CryptReleaseContext(hProv, 0);
		return dwReturn;
	}

	if (!CryptHashData(hHash, static_cast<const BYTE*>(pData), dwDataLen, 0))
	{
		dwReturn = GetLastError();
		CryptDestroyHash(hHash);
		CryptReleaseContext(hProv, 0);
		return dwReturn;
	}

	DWORD dwSize;
	DWORD dwLen = sizeof(dwSize);
	CryptGetHashParam(hHash, HP_HASHSIZE, reinterpret_cast<BYTE*>(&dwSize), &dwLen, 0);

	BYTE* pHash = new BYTE[dwSize];
	dwLen = dwSize;
	CryptGetHashParam(hHash, HP_HASHVAL, pHash, &dwLen, 0);

	lstrcpy(pszMD5, _T(""));
	TCHAR szTemp[3];
	TCHAR *szFmt = bCap ? _T("%X%X") : _T("%x%x");
	for (DWORD i = 0; i < dwLen; ++i)
	{
		wsprintf(szTemp, szFmt, pHash[i] >> 4, pHash[i] & 0xf);
		lstrcat(pszMD5, szTemp);
	}
	delete [] pHash;

	CryptDestroyHash(hHash);
	CryptReleaseContext(hProv, 0);

	return dwReturn;
}

int _tmain(int argc, TCHAR *argv[])
{
	TCHAR szMD5[33];

	char szTest1[] = {'1', '2', '3'};

	MD5(szTest1, sizeof(szTest1), szMD5, TRUE);
	_tprintf(_T("%s\r\n"), szMD5);

	char szTest2[] = {0x01, 0x02, 0x03};

	MD5(szTest2, sizeof(szTest2), szMD5);
	_tprintf(_T("%s\r\n"), szMD5);

	system("pause");

	return 0; 
}