Click here to Skip to main content
14,969,930 members
Articles / Desktop Programming / WPF
Posted 10 Jun 2009


14 bookmarked

Binding Passwords

Rate me:
Please Sign up or sign in to vote.
5.00/5 (10 votes)
29 Jun 2009CPOL
Binding passwords

Those who've been following my blog and conversations with the WPF Disciples know that I love the databinding power of WPF, and in almost all cases, I'm a very happy bunny. There is one stain in the awe inspiring goodness that is bound applications, and that’s the PasswordBox. Superficially, this control looks like a textbox, but there is a problem when you write MVVM applications and rely on binding the way I do; you can't bind to it. Yes, you heard it right, you can't bind with a PasswordBox.

There’s a good reason for this lack of binding – PasswordBox.Password is not a Dependency Property, ostensibly because this would result in the password being stored in clear text in memory, which is a potential security concern. If, however, you aren't too worried about this potential security breach, there is a workaround. Good news, folks – the following class (taken from my forthcoming Twitter client Songbird) is a way to perform binding with the PasswordBox.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;

namespace SongBird.Infrastructure
    /// <summary>
    /// This class adds binding capabilities to the standard WPF PasswordBox.
    /// </summary>
    public class BoundPasswordBox
        #region BoundPassword
        private static bool _updating = false;

        /// <summary>
        /// BoundPassword Attached Dependency Property
        /// </summary>
        public static readonly DependencyProperty BoundPasswordProperty =
                new FrameworkPropertyMetadata(string.Empty, OnBoundPasswordChanged));

        /// <summary>
        /// Gets the BoundPassword property.
        /// </summary>
        public static string GetBoundPassword(DependencyObject d)
            return (string)d.GetValue(BoundPasswordProperty);

        /// <summary>
        /// Sets the BoundPassword property.
        /// </summary>
        public static void SetBoundPassword(DependencyObject d, string value)
            d.SetValue(BoundPasswordProperty, value);

        /// <summary>
        /// Handles changes to the BoundPassword property.
        /// </summary>
        private static void OnBoundPasswordChanged(
            DependencyObject d,
            DependencyPropertyChangedEventArgs e)
            PasswordBox password = d as PasswordBox;
            if (password != null)
                // Disconnect the handler while we're updating.
                password.PasswordChanged -= PasswordChanged;

            if (e.NewValue != null)
                if (!_updating)
                    password.Password = e.NewValue.ToString();
                password.Password = string.Empty;
            // Now, reconnect the handler.
            password.PasswordChanged += new RoutedEventHandler(PasswordChanged);

        /// <summary>
        /// Handles the password change event.
        /// </summary>
        static void PasswordChanged(object sender, RoutedEventArgs e)
            PasswordBox password = sender as PasswordBox;
            _updating = true;
            SetBoundPassword(password, password.Password);
            _updating = false;


Using it couldn't be simpler, just add a reference to the namespace in your XAML, and update your PasswordBox with the BoundPasswordBox class. You've now got a bindable PasswordBox.

    password:BoundPasswordBox.BoundPassword="{Binding Path=Password,


This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


About the Author

Pete O'Hanlon
United Kingdom United Kingdom
A developer for over 30 years, I've been lucky enough to write articles and applications for Code Project as well as the Intel Ultimate Coder - Going Perceptual challenge. I live in the North East of England with 2 wonderful daughters and a wonderful wife.

I am not the Stig, but I do wish I had Lotus Tuned Suspension.

Comments and Discussions

QuestionPasswordBox.Password Pin
jperlinski21-Jan-13 4:31
Memberjperlinski21-Jan-13 4:31 
QuestionThanks! Pin
cruzanPC3-May-12 3:45
MembercruzanPC3-May-12 3:45 
GeneralMy vote of 5 Pin
RobCroll21-Feb-11 15:52
MemberRobCroll21-Feb-11 15:52 
GeneralBoundPasswordProperty default value Pin
sbhl1-Sep-10 22:37
Membersbhl1-Sep-10 22:37 
GeneralRe: BoundPasswordProperty default value Pin
Pete O'Hanlon1-Sep-10 22:46
mvePete O'Hanlon1-Sep-10 22:46 
GeneralRe: BoundPasswordProperty default value Pin
sbhl1-Sep-10 23:10
Membersbhl1-Sep-10 23:10 
GeneralRe: BoundPasswordProperty default value Pin
sbhl2-Sep-10 0:01
Membersbhl2-Sep-10 0:01 
GeneralRe: BoundPasswordProperty default value Pin
sbhl2-Sep-10 2:39
Membersbhl2-Sep-10 2:39 
GeneralGreat! Pin
Paul Eie12-Apr-10 0:06
MemberPaul Eie12-Apr-10 0:06 
GeneralRe: Great! Pin
Pete O'Hanlon12-Apr-10 1:40
mvePete O'Hanlon12-Apr-10 1:40 
QuestionIs there any reason the binding password code not work? Pin
JJChen4019-Jun-09 15:22
MemberJJChen4019-Jun-09 15:22 
AnswerRe: Is there any reason the binding password code not work? Pin
Pete O'Hanlon21-Jun-09 11:02
mvePete O'Hanlon21-Jun-09 11:02 
GeneralRe: Is there any reason the binding password code not work? [modified] Pin
JJChen403-Jul-09 7:29
MemberJJChen403-Jul-09 7:29 
Generalthanks. Pin
Michael Sync10-Jun-09 15:54
MemberMichael Sync10-Jun-09 15:54 
GeneralRe: thanks. Pin
Pete O'Hanlon10-Jun-09 21:54
mvePete O'Hanlon10-Jun-09 21:54 

General General    News News    Suggestion Suggestion    Question Question    Bug Bug    Answer Answer    Joke Joke    Praise Praise    Rant Rant    Admin Admin   

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.