C / C++ / MFC

LPTSTR Base64Decode(LPCTSTR lpData, DWORD dwSize)
{
	DWORD dwResult = 0;
	if(CryptStringToBinary(lpData, dwSize, CRYPT_STRING_BASE64, NULL, &dwResult,NULL,NULL))
	{
		LPTSTR lpszBase64Decoded = new TCHAR[dwResult+(sizeof(TCHAR) * 2)];
		memset(lpszBase64Decoded,0,dwResult);
		if(CryptStringToBinary(lpData, dwSize, CRYPT_STRING_BASE64,(BYTE *)lpszBase64Decoded, &dwResult,NULL,NULL))
		{
			*(LPWORD)(lpszBase64Decoded + (dwResult / sizeof(TCHAR))) = 0;

			return lpszBase64Decoded;
		}
	}
	return NULL;
}

LPTSTR Base64Encode(LPCBYTE lpData, DWORD dwSize, BOOL bStripCRLF, DWORD *dwBufSize)
{
	DWORD dwResult = 0;
	if(CryptBinaryToString(lpData, dwSize, CRYPT_STRING_BASE64, NULL, &dwResult))
	{
		LPTSTR lpszBase64 = new TCHAR[dwResult];
		if(CryptBinaryToString(lpData, dwSize, CRYPT_STRING_BASE64, lpszBase64, &dwResult))
		{
			TCHAR pByteLF = *(LPWORD)(lpszBase64 + dwResult -1);
			TCHAR pByteCR = *(LPWORD)(lpszBase64 + dwResult -2);
			if(pByteCR == 0x0D && pByteLF == 0x0A)
			{
				*(LPWORD)(lpszBase64 + dwResult -2) = 0;
			}
			*dwBufSize = dwResult;
			return lpszBase64;
		}
	}
	return NULL;
}


BYTE* Base64Decode2(LPCTSTR lpData, DWORD dwSize, DWORD *dwBufSize)
{
	DWORD dwResult = 0;
	if(CryptStringToBinary(lpData, dwSize, CRYPT_STRING_BASE64, NULL, &dwResult,NULL,NULL))
	{
		BYTE * decodedStr;
		decodedStr = new BYTE;
		LPTSTR lpszBase64Decoded = new TCHAR[dwResult+(sizeof(TCHAR) * 2)];
		memset(decodedStr,0,dwResult);
		if(CryptStringToBinary(lpData, dwSize, CRYPT_STRING_BASE64,decodedStr, &dwResult,NULL,NULL))
		{
			*dwBufSize = dwResult;
			return decodedStr;
		}
	}
	return NULL;
}
LPTSTR Base64Encode2(BYTE* lpData, DWORD dwSize, BOOL bStripCRLF, DWORD *dwbufSize)
{
	DWORD dwResult = 0;
	if(CryptBinaryToString(lpData, dwSize, CRYPT_STRING_BASE64, NULL, &dwResult))
	{
		LPTSTR lpszBase64 = new TCHAR[dwResult];
		if(CryptBinaryToString(lpData, dwSize, CRYPT_STRING_BASE64, lpszBase64, &dwResult))
		{
			TCHAR pByteLF = *(LPWORD)(lpszBase64 + dwResult -1);
			TCHAR pByteCR = *(LPWORD)(lpszBase64 + dwResult -2);
			if(pByteCR == 0x0D && pByteLF == 0x0A)
			{
				*(LPWORD)(lpszBase64 + dwResult -2) = 0;
			}
			*dwbufSize = dwResult;
			return lpszBase64;
		}
	}
	return NULL;
}
DWORD TripleDESdecrypt(TCHAR *cyphertext,DWORD ctlen,TCHAR *passwd,DWORD pwlen,TCHAR *plaintext,DWORD *ptlen)
{
	HCRYPTPROV hProv;
	HCRYPTHASH hHash;
	HCRYPTKEY hKey;
	DWORD dwSizeNeeded =0;

	BOOL result = CryptAcquireContext(&hProv,NULL,MS_STRONG_PROV,PROV_RSA_FULL,0);
	result = CryptCreateHash(hProv,CALG_MD5,0,0,&hHash);
	result = CryptHashData(hHash,(BYTE *)passwd,pwlen,0);
	result = CryptDeriveKey(hProv,CALG_3DES,hHash,0,&hKey);
	BYTE PadMode = CRYPT_MODE_ECB;
	result = CryptSetKeyParam(hKey, PKCS5_PADDING, &PadMode, 0);
	if(*ptlen >= ctlen)
	{
		memcpy(plaintext,cyphertext,*ptlen);
		result = CryptDecrypt(hKey,NULL,1,0,(BYTE *)plaintext,&ctlen);
		*ptlen=ctlen;
	}
	else
	{
		dwSizeNeeded = ctlen * sizeof(TCHAR);
	}
	CryptDestroyKey(hKey);
	CryptDestroyHash(hHash);
	CryptReleaseContext(hProv,0);
	return dwSizeNeeded;
}
int main()
{
	
	BYTE* decodedStr;
	HCRYPTPROV hCryptProv;
	HCRYPTHASH hHash = 0;
	HCRYPTKEY hKey = 0;

	TCHAR szKey[] = _T("h3bmull3r");
	TCHAR szUnencrypted[] = _T("");
	TCHAR * pszEncrypted = NULL;
	TCHAR * pszBase64 = NULL;
	TCHAR * pszBase64Decoded = NULL;
	TCHAR * psz3DESDecoded = NULL;
	DWORD dwSizeNeeded;
	DWORD BufSize;
	DWORD dwUnEncryptedSize;
	DWORD dwEncryptedSize;
	DWORD KeySize;

	////convert Key
	TCHAR * NewKey  = Base64Encode((LPCBYTE)&szKey,_tcslen(szKey) * sizeof(TCHAR),FALSE, &KeySize);
	_tcscpy(szKey, NewKey);

	pszBase64 = _T("bZVLVixsjgTxsWbwmAGitRR0T86AM9Kam4BYRR+Dukc9p9vhwUBAzCSlZ463ZInufJRE+7ridImlz/aJUJbVhg==");

	BYTE* TEST = Base64Decode2(pszBase64,_tcslen(pszBase64) * sizeof(TCHAR), &dwEncryptedSize);
	TCHAR * pszEncrypted2 = reinterpret_cast<TCHAR *>(TEST);
	pszEncrypted = pszEncrypted2;
	//Decrypt the string with 3DES algorithm using key
	dwUnEncryptedSize = NULL;
	dwSizeNeeded = TripleDESdecrypt(pszEncrypted,dwEncryptedSize * sizeof(TCHAR),szKey,_tcslen(szKey),szUnencrypted,&dwUnEncryptedSize);
	psz3DESDecoded = new TCHAR[dwSizeNeeded];
	TripleDESdecrypt(pszEncrypted,dwEncryptedSize * sizeof(TCHAR),szKey,_tcslen(szKey),psz3DESDecoded,&dwSizeNeeded);
	//Decode the base64 encoded message back to ascii
	pszBase64Decoded = Base64Decode(psz3DESDecoded,_tcslen(psz3DESDecoded) * sizeof(TCHAR));

\



	//Do they match?

	MessageBox(NULL,0 == _tcscmp(pszBase64Decoded,szUnencrypted) ? _T("Strings Match"):_T("Strings do NOT Match"),_T(""),MB_OK);

	delete [] pszBase64;
	delete [] pszBase64Decoded;
	delete [] pszEncrypted;
	//delete [] pszEncrypted2;

	return 0;
}