/// <summary>
/// This will the allocated memory from method <see cref="SecureStringToGlobalAllocUni"/>.
/// </summary>
/// <remarks>
/// This method is located in the <see cref="Marshal"/> class in .NET Framework v2.0
/// </remarks>
public static void ZeroFreeGlobalAllocUni(IntPtr s)
{
// Demand Permission
new CryptographicPermission(CryptographicPermissionFlags.Decrypt).Demand();
Win32Native.ZeroMemory(s, (uint)Win32Native.lstrlenW(s) * 2);
Marshal.FreeHGlobal(s);
}
/// <summary>
/// This method creates and displays a configurable dialog box that accepts credentials information from a user.
/// </summary>
/// <param name="targetName">Contains the name of the target for the credentials,
/// typically a server name. For distributed file system (DFS) connections,
/// this string is of the form "servername\sharename".
/// This parameter is used to identify Target Information when storing and retrieving credentials.
/// </param>
/// <param name="caption">String containing the title for the dialog box.</param>
/// <param name="message">String containing a brief message to display in the dialog box.</param>
/// <param name="owner">Specifies the handle to the parent window of the dialog box.
/// If this member is NULL, the desktop will be the parent window of the dialog box.
/// </param>
/// <returns><see cref="SecureCredential"/> object with the supplied credentials.</returns>
/// <permission cref="UIPermission">Demand for <see cref="UIPermissionWindow.SafeTopLevelWindows"/> permission.</permission>
public static SecureCredential PromptForSecureCredentials(string targetName, string caption, string message, IntPtr owner)
{
// Parameter validation
if (targetName == null)
{
throw new ArgumentNullException("targetName");
}
if (caption == null)
{
caption = String.Empty;
}
if (message == null)
{
message = String.Empty;
}
new UIPermission(UIPermissionWindow.SafeTopLevelWindows).Demand();
// Uncommment this lines to use custom bitmap
// Bitmap credBMP = new Bitmap(@"..\credui.bmp");
// replace IntPtr.Zero by credBMP.GetHbitmap()
Win32Native.CREDUI_INFO creditUI = new Win32Native.CREDUI_INFO(owner, caption, message, IntPtr.Zero);
int saveCredentials = 0;
StringBuilder user = new StringBuilder(Win32Native.MAX_USER_NAME);
byte[] pwd = new byte[Win32Native.MAX_PASSWORD];
GCHandle pwdHandle = GCHandle.Alloc(pwd, GCHandleType.Pinned);
try
{
Win32Native.CredUiFlags flags = Win32Native.CredUiFlags.GENERIC_CREDENTIALS |
Win32Native.CredUiFlags.SHOW_SAVE_CHECK_BOX |
Win32Native.CredUiFlags.ALWAYS_SHOW_UI |
Win32Native.CredUiFlags.EXPECT_CONFIRMATION |
Win32Native.CredUiFlags.INCORRECT_PASSWORD;
//For more info see:
//http://msdn.microsoft.com/library/default.asp?url=/library/en-us/security/security/creduipromptforcredentials.asp
//http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnnetsec/html/dpapiusercredentials.asp?frame=true
Win32Native.CredUIReturnCodes result = Win32Native.CredUIPromptForCredentialsW(
ref creditUI, targetName,
IntPtr.Zero, 0,
user, Win32Native.MAX_USER_NAME,
pwdHandle.AddrOfPinnedObject(), pwd.Length,
ref saveCredentials, flags);
switch (result)
{
case Win32Native.CredUIReturnCodes.NO_ERROR:
StringBuilder usr = new StringBuilder(Win32Native.MAX_USER_NAME);
StringBuilder domain = new StringBuilder(Win32Native.MAX_DOMAIN);
result = Win32Native.CredUIParseUserNameW(user.ToString(), usr, Win32Native.MAX_USER_NAME, domain, Win32Native.MAX_DOMAIN);
if (result == Win32Native.CredUIReturnCodes.NO_ERROR)
{
if (saveCredentials == 1)
{
ConfirmCredentials(targetName, true);
}
unsafe
{
return(new SecureCredential(usr.ToString(), (char *)pwdHandle.AddrOfPinnedObject().ToPointer(), Win32Native.lstrlenW(pwdHandle.AddrOfPinnedObject()), domain.ToString()));
}
}
else
{
throw new SecurityException(TranslateReturnCode(result));
}
case Win32Native.CredUIReturnCodes.ERROR_CANCELLED:
return(null);
default:
throw new SecurityException(TranslateReturnCode(result));
}
}
finally
{
// Clear pwd data.
Array.Clear(pwd, 0, pwd.Length);
// Zero out the memory buffer
Win32Native.ZeroMemory(pwdHandle.AddrOfPinnedObject(), (uint)pwd.Length);
// Free the allocated handle
if (pwdHandle.IsAllocated)
{
pwdHandle.Free();
}
}
}
