public unsafe static void ProcessMessage_NEW(SafeMsgHandle hMsg, FileStream file)
{
// Variables
int BufSize = 1024 * 1024;
BinaryReader stream = null;
byte[] pbData = null;
long dwRemaining = 0;
bool bFinal = false;
bool bResult = false;

// Process message
dwRemaining = file.Length;
stream = new BinaryReader(file);
do
{
// Read one chunk of data
pbData = stream.ReadBytes(BufSize);
if (pbData.Length == 0)
{
break;
}

bFinal = (dwRemaining <= BufSize);
fixed (byte* pAux = &pbData[0])
{
bResult = CryptMsgUpdate(
hMsg.DangerousGetHandle(),
new IntPtr(pAux),
pbData.Length,
bFinal
);
if (!bResult)
{
throw new Exception("CryptMsgUpdate error #" + Marshal.GetLastWin32Error().ToString(), new Win32Exception(Marshal.GetLastWin32Error()));
}

Win32.CheckEnvelopeAlg(hMsg);
Win32.Decrypt(hMsg);

}


dwRemaining = dwRemaining - pbData.Length;

} while (!bFinal);
}

// Decrypt the message
bResult = CryptMsgControl(
hMsg,
0,
CMSG_CTRL_DECRYPT,
ref DecryptPara
);
if (!bResult)
{
// throw new Exception("CryptMsgControl error #" + Marshal.GetLastWin32Error().ToString(), new Win32Exception(Marshal.GetLastWin32Error()));
}