"David Ching" <>
Wed, 24 Dec 2008 07:12:50 -0800
"Manoj Jangid" <> wrote in message

Hi I am calling a function from MFC dll in C# application.
This function work with C++ application but when I was calling from C#
application terminates unexpectedly.

can anyone tell me why this happening?

I am pasting my source code here
C# code
       private void button1_Click(object sender, EventArgs e)
           string strPassWord = textBox1.Text;
           string strHash = "";
           PasswordHash(strPassWord,ref strHash);

PasswordHash function in my MFC regular statically linked to MFC dll
C++ code

bool __stdcall PasswordHash(LPCTSTR lpPassword, LPTSTR lpszHash)
CString strPassword(lpPassword);
bool bReturn = false;
BYTE pbHash[16];
DWORD dwHashLen= 16;
DWORD cbContent= strPassword.GetLength() * sizeof(TCHAR);
BYTE* pbContent= (BYTE *) strPassword.GetBuffer(cbContent);

if(CryptAcquireContext(&hCryptProv, NULL, NULL, PROV_RSA_FULL,
if(CryptCreateHash(hCryptProv,CALG_MD5,0, 0, &hHash))
if(CryptHashData(hHash, pbContent, cbContent, 0))
if(CryptGetHashParam(hHash, HP_HASHVAL, pbHash, &dwHashLen, 0))
LPTSTR lpTmp = lpszHash;
for (int i = 0; i < 16; i++)
const size_t nlen = sizeof(pbHash[i])+2;
lpTmp += 2;
bReturn = true;
CryptReleaseContext(hCryptProv, 0);
return bReturn;

Thanks for the excellent problem description. Could you please provide one
more piece of info: how do you prototype PasswordHash() using P/Invoke?
e.g. since lpszHash is an output string, you need to prototype it similar
to the lpString parameter in GetWindowText as shown:

    [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
    static extern int GetWindowText(IntPtr hWnd, StringBuilder lpString, int

If you don't, you could well be overwriting memory that doesn't exist in
your loop.

-- David

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