<%@ Page language="VJ#" %>
<%@ Import Namespace="System.Web" %>
<%@ Import Namespace="System.Web.Security" %>
<%@ Import Namespace="System.Security.Principal" %>
<%@ Import Namespace="System.Runtime.InteropServices" %>

<script runat=server>
public static int LOGON32_LOGON_INTERACTIVE = 2;
public static int LOGON32_PROVIDER_DEFAULT = 0;

WindowsImpersonationContext impersonationContext;

/** @attribute DllImport("advapi32.dll") */
public static native int LogonUserA(String lpszUserName,
	String lpszDomain,
	String lpszPassword,
	int dwLogonType,
	int dwLogonProvider,
	System.IntPtr[] phToken);

/** @attribute DllImport("advapi32.dll",
 CharSet=CharSet.Auto, SetLastError=true) */
public static native int DuplicateToken(System.IntPtr hToken,
	int impersonationLevel,
	System.IntPtr[] hNewToken);

/** @attribute DllImport("kernel32.dll",CharSet=CharSet.Auto) */
public static native  boolean CloseHandle(System.IntPtr[] handle);


/** @attribute DllImport("advapi32.dll",
 	 CharSet=CharSet.Auto,SetLastError=true) */
public static native boolean RevertToSelf();

public void Page_Load(Object s, System.EventArgs e)
{
	if(impersonateValidUser("username", "domain", " password"))
	{
		//Insert your code that runs under the security context of a specific user here.
		undoImpersonation();
	}
	else
	{
		//Your impersonation failed. Therefore, include a fail-safe mechanism here.
	}
}

private boolean impersonateValidUser(String userName, String domain, String password)
{
	WindowsIdentity tempWindowsIdentity;
	System.IntPtr[] token = new System.IntPtr[1];
	System.IntPtr[] tokenDuplicate = new System.IntPtr[1];

	if(RevertToSelf())
	{
		if(LogonUserA(userName, domain, password, LOGON32_LOGON_INTERACTIVE,
			LOGON32_PROVIDER_DEFAULT, token) != 0)
		{
			if(DuplicateToken(token[0], 2, tokenDuplicate) != 0)
			{
				tempWindowsIdentity = new WindowsIdentity(tokenDuplicate[0]);
				impersonationContext = tempWindowsIdentity.Impersonate();
				if (impersonationContext != null)
				{
					CloseHandle(tokenDuplicate);
					CloseHandle(token);
					return true;
				}
			}
		}
	}
	if(!token[0].Equals(System.IntPtr.Zero))
		CloseHandle(token);
	if(!tokenDuplicate[0].Equals(System.IntPtr.Zero))
		CloseHandle(tokenDuplicate);
	return false;

}

private void undoImpersonation()
{
	impersonationContext.Undo();
}