Show Authentication dialog in C# for windows Vista/7

Question

I want to get network login credentials from a user.

I'm using .NET 3.5 with C#. Up until now I used the CredUIPromptForCredentials call (a very useful link on how to use it can be found here)

My problem is that the CredUIPromptForCredentials API call shows the old windows 2000/XP credentials dialog and not the new Vista/7 one.

I've read on msdn that I should use the CredUIPromptForWindowsCredentials function.

Can someone post an example of how to use it with C#? I also need to be able to get the credentials that were entered.

Answer 1

I managed to implement a solution that is working for me.

Here is the source code:

    [DllImport("ole32.dll")]
    public static extern void CoTaskMemFree(IntPtr ptr);

    [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
    private struct CREDUI_INFO
    {
        public int cbSize;
        public IntPtr hwndParent;
        public string pszMessageText;
        public string pszCaptionText;
        public IntPtr hbmBanner;
    }  


    [DllImport("credui.dll", CharSet = CharSet.Auto)]
    private static extern bool CredUnPackAuthenticationBuffer(int dwFlags,
                                                               IntPtr pAuthBuffer,
                                                               uint cbAuthBuffer,
                                                               StringBuilder pszUserName,
                                                               ref int pcchMaxUserName,
                                                               StringBuilder pszDomainName,
                                                               ref int pcchMaxDomainame,
                                                               StringBuilder pszPassword,
                                                               ref int pcchMaxPassword);

    [DllImport("credui.dll", CharSet = CharSet.Auto)]
    private static extern int CredUIPromptForWindowsCredentials(ref CREDUI_INFO notUsedHere,
                                                                 int authError,
                                                                 ref uint authPackage,
                                                                 IntPtr InAuthBuffer,
                                                                 uint InAuthBufferSize,
                                                                 out IntPtr refOutAuthBuffer,
                                                                 out uint refOutAuthBufferSize,
                                                                 ref bool fSave,
                                                                 int flags);



    public static void GetCredentialsVistaAndUp(string serverName, out NetworkCredential networkCredential)
    {
        CREDUI_INFO credui = new CREDUI_INFO();
        credui.pszCaptionText = "Please enter the credentails for " + serverName;
        credui.pszMessageText = "DisplayedMessage";
        credui.cbSize = Marshal.SizeOf(credui);
        uint authPackage = 0;
        IntPtr outCredBuffer = new IntPtr();
        uint outCredSize;
        bool save = false;
        int result = CredUIPromptForWindowsCredentials(ref credui,
                                                       0,
                                                       ref authPackage,
                                                       IntPtr.Zero,
                                                       0,
                                                       out outCredBuffer,
                                                       out outCredSize,
                                                       ref save,
                                                       1 /* Generic */);

        var usernameBuf = new StringBuilder(100);
        var passwordBuf  = new StringBuilder(100);
        var domainBuf = new StringBuilder(100);

        int maxUserName = 100;
        int maxDomain = 100;
        int maxPassword = 100;
        if (result == 0)
        {
            if (CredUnPackAuthenticationBuffer(0, outCredBuffer, outCredSize, usernameBuf, ref maxUserName,
                                               domainBuf, ref maxDomain, passwordBuf, ref maxPassword))
            {
                //TODO: ms documentation says we should call this but i can't get it to work
                //SecureZeroMem(outCredBuffer, outCredSize);

                //clear the memory allocated by CredUIPromptForWindowsCredentials 
                CoTaskMemFree(outCredBuffer);
                networkCredential = new NetworkCredential()
                                        {
                                            UserName = usernameBuf.ToString(),
                                            Password = passwordBuf.ToString(),
                                            Domain = domainBuf.ToString()
                                        };
                return;
            }
        }

        networkCredential = null;
    }

I still need to work out the fine details such as how to remember the last credentials that were entered etc...

But the major part works.

Answer 2

Here is some code to go on extracted from bytes.com post:

[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
struct _CREDUI_INFO
{
  public int cbSize;
  public IntPtr hwndParent;
  public string pszMessageText;
  public string pszCaptionText;
  public IntPtr hbmBanner;
}
class Program
{
  [DllImport("credui.dll", CharSet=CharSet.Unicode)]
  internal static extern uint CredUIPromptForWindowsCredentials(ref
    _CREDUI_INFO notUsedHere,
    int authError,
    ref uint authPackage,
    IntPtr InAuthBuffer,
    uint InAuthBufferSize,
    out IntPtr refOutAuthBuffer,
    out uint refOutAuthBufferSize,
    ref bool fSave,
    int flags);

  const int CREDUIWIN_AUTHPACKAGE_ONLY = 0x10;

  static void Main()
  {
    _CREDUI_INFO credui = new _CREDUI_INFO();
    credui.cbSize = Marshal.SizeOf(credui);
    credui.pszCaptionText = "Testje";
    credui.pszMessageText = "Message";
    uint authPackage = 0;
    IntPtr outCredBuffer;
    uint outCredSize;
    bool save = false;

    uint ret = CredUIPromptForWindowsCredentials(ref credui,
      0,
      ref authPackage,
      IntPtr.Zero,
      0,
      out outCredBuffer,
      out outCredSize,
      ref save,
      CREDUIWIN_AUTHPACKAGE_ONLY);

    if(ret != 0)
    {
      // failed to load function...
      // ...
    }
    else
    {
      // extract credentials from the buffer returned, using more
      //   credui.dll API's .
      // ...
    }
  }
}