Allow specifying password to skip dialog

VncSharp/PasswordDialog.cs

@@ -20,6 +20,7 @@
 using System.Collections;
 using System.ComponentModel;
 using System.Windows.Forms;
+using System.Security;
 
 namespace VncSharp
 {
@@ -125,12 +126,16 @@ private void InitializeComponent()
 		/// Creates an instance of PasswordDialog and uses it to obtain the user's password.
 		/// </summary>
 		/// <returns>Returns the user's password as entered, or null if he/she clicked Cancel.</returns>
-		public static string GetPassword()
+		public static SecureString GetPassword()
 		{
 			using(PasswordDialog dialog = new PasswordDialog()) {
 				if (dialog.ShowDialog() == DialogResult.OK) {
-					return dialog.Password;
-				} else {
+                    SecureString Result = new SecureString();
+                    for (int i = 0; i < dialog.Password.Length; i++) {
+                        Result.AppendChar(dialog.Password[i]);
+                    }
+                    return Result;
+                } else {
 					// If the user clicks Cancel, return null and not the empty string.
 					return null;
 				}

VncSharp/RemoteDesktop.cs

@@ -25,6 +25,7 @@
 using System.Drawing.Drawing2D;
 
 using VncSharp.Encodings;
+using System.Security;
 
 namespace VncSharp
 {
@@ -36,7 +37,7 @@ namespace VncSharp
 	/// <summary>
 	/// When connecting to a VNC Host, a password will sometimes be required.  Therefore a password must be obtained from the user.  A default Password dialog box is included and will be used unless users of the control provide their own Authenticate delegate function for the task.  For example, this might pull a password from a configuration file of some type instead of prompting the user.
 	/// </summary>
-	public delegate string AuthenticateDelegate();
+	public delegate SecureString AuthenticateDelegate();
 
 	/// <summary>
 	/// SpecialKeys is a list of the various keyboard combinations that overlap with the client-side and make it
@@ -83,6 +84,7 @@ public class RemoteDesktop : Panel
 		Image  designModeDesktop;			     // Used when painting control in VS.NET designer
 		VncClient vnc;						     // The Client object handling all protocol-level interaction
 		int port = 5900;					     // The port to connect to on remote host (5900 is default)
+		SecureString _Password = null;           // The password to authenticate with
 		bool passwordPending = false;		     // After Connect() is called, a password might be required.
 		bool fullScreenRefresh = false;		     // Whether or not to request the entire remote screen be sent.
         VncDesktopTransformPolicy desktopPolicy;
@@ -135,6 +137,13 @@ public int VncPort {
 			}
 		}
 
+        /// <summary>
+        /// The password to authenticate with.  If left blank, user will be prompted for the password
+        /// </summary>
+        public SecureString Password {
+            set { _Password = value; }
+        }
+
 		/// <summary>
 		/// True if the RemoteDesktop is connected and authenticated (if necessary) with a remote VNC Host; otherwise False.
 		/// </summary>
@@ -352,13 +361,13 @@ public void Connect(string host, int display, bool viewOnly, bool scaled)
 
             if (passwordPending) {
                 // Server needs a password, so call which ever method is refered to by the GetPassword delegate.
-                string password = GetPassword();
+                if ((_Password == null) || (_Password.Length == 0)) _Password = GetPassword();
 
-                if (password == null) {
+                if (_Password == null) {
                     // No password could be obtained (e.g., user clicked Cancel), so stop connecting
                     return;
                 } else {
-                    Authenticate(password);
+                    Authenticate(_Password);
                 }
             } else {
                 // No password needed, so go ahead and Initialize here
@@ -372,7 +381,7 @@ public void Connect(string host, int display, bool viewOnly, bool scaled)
 		/// <exception cref="System.InvalidOperationException">Thrown if the RemoteDesktop control is already Connected.  See <see cref="VncSharp.RemoteDesktop.IsConnected" />.</exception>
 		/// <exception cref="System.NullReferenceException">Thrown if the password is null.</exception>
 		/// <param name="password">The user's password.</param>
-		public void Authenticate(string password)
+		public void Authenticate(SecureString password)
 		{
 			InsureConnection(false);
 			if (!passwordPending) throw new InvalidOperationException("Authentication is only required when Connect() returns True and the VNC Host requires a password.");

VncSharp/VncClient.cs

@@ -23,6 +23,8 @@
 using System.Windows.Forms;
 
 using VncSharp.Encodings;
+using System.Security;
+using System.Runtime.InteropServices;
 
 namespace VncSharp
 {
@@ -216,7 +218,7 @@ protected byte GetSupportedSecurityType(byte[] types)
 		/// </summary>
 		/// <param name="password">The password to use.</param>
 		/// <returns>Returns True if Authentication worked, otherwise False.</returns>
-		public bool Authenticate(string password)
+		public bool Authenticate(SecureString password)
 		{
 			if (password == null) throw new ArgumentNullException("password");
 
@@ -245,7 +247,7 @@ public bool Authenticate(string password)
 		/// Performs VNC Authentication using VNC DES encryption.  See the RFB Protocol doc 6.2.2.
 		/// </summary>
 		/// <param name="password">A string containing the user's password in clear text format.</param>
-		protected void PerformVncAuthentication(string password)
+		protected void PerformVncAuthentication(SecureString password)
 		{
 			byte[] challenge = rfb.ReadSecurityChallenge();
 			rfb.WriteSecurityResponse(EncryptChallenge(password, challenge));
@@ -257,15 +259,27 @@ protected void PerformVncAuthentication(string password)
 		/// <param name="password">The user's password.</param>
 		/// <param name="challenge">The challenge sent by the server.</param>
 		/// <returns>Returns the encrypted challenge.</returns>
-		protected byte[] EncryptChallenge(string password, byte[] challenge)
+		protected byte[] EncryptChallenge(SecureString password, byte[] challenge)
 		{
 			byte[] key = new byte[8];
 
+            // Get plain text password
+            string PlaintextPassword = "";
+            IntPtr UnmanagedString = IntPtr.Zero;
+            try {
+                UnmanagedString = Marshal.SecureStringToBSTR(password);
+                PlaintextPassword = Marshal.PtrToStringAuto(UnmanagedString);
+            } finally {
+                if (UnmanagedString != IntPtr.Zero) {
+                    Marshal.ZeroFreeBSTR(UnmanagedString);
+                }
+            }
+
 			// Key limited to 8 bytes max.
-			if (password.Length >= 8) {
-				System.Text.Encoding.ASCII.GetBytes(password, 0, 8, key, 0);
+			if (PlaintextPassword.Length >= 8) {
+				System.Text.Encoding.ASCII.GetBytes(PlaintextPassword, 0, 8, key, 0);
 			} else {
-				System.Text.Encoding.ASCII.GetBytes(password, 0, password.Length, key, 0);
+				System.Text.Encoding.ASCII.GetBytes(PlaintextPassword, 0, password.Length, key, 0);
 			}			
 
 			// VNC uses reverse byte order in key