Binding PasswordBox

uwp PasswordBoxHelper

    public static class PasswordBoxHelper
    {
        public static readonly DependencyProperty PasswordProperty = DependencyProperty.RegisterAttached(
            "Password", typeof(string), typeof(PasswordBoxHelper), new PropertyMetadata(default(string),OnPasswordPropertyChanged));

        public static void SetPassword(DependencyObject element, string value)
        {
            element.SetValue(PasswordProperty, value);
        }

        public static string GetPassword(DependencyObject element)
        {
            return (string) element.GetValue(PasswordProperty);
        }

        public static readonly DependencyProperty AttachProperty = DependencyProperty.RegisterAttached(
            "Attach", typeof(bool), typeof(PasswordBoxHelper), new PropertyMetadata(default(bool),Attach));

        public static void SetAttach(DependencyObject element, bool value)
        {
            element.SetValue(AttachProperty, value);
        }

        public static bool GetAttach(DependencyObject element)
        {
            return (bool) element.GetValue(AttachProperty);
        }

        public static readonly DependencyProperty IsUpdatingProperty = DependencyProperty.RegisterAttached(
            "IsUpdating", typeof(bool), typeof(PasswordBoxHelper), new PropertyMetadata(default(bool)));

        public static void SetIsUpdating(DependencyObject element, bool value)
        {
            element.SetValue(IsUpdatingProperty, value);
        }

        public static bool GetIsUpdating(DependencyObject element)
        {
            return (bool) element.GetValue(IsUpdatingProperty);
        }

        private static void OnPasswordPropertyChanged(DependencyObject sender,
         DependencyPropertyChangedEventArgs e)
        {
            PasswordBox passwordBox = sender as PasswordBox;
            if (passwordBox != null)
            {
                passwordBox.PasswordChanged -= PasswordChanged;

                if (!(bool)GetIsUpdating(passwordBox))
                {
                    passwordBox.Password = (string)e.NewValue;
                }
                passwordBox.PasswordChanged += PasswordChanged;
            }
        }

        private static void Attach(DependencyObject sender,
            DependencyPropertyChangedEventArgs e)
        {
            PasswordBox passwordBox = sender as PasswordBox;

            if (passwordBox == null)
                return;

            if ((bool)e.OldValue)
            {
                passwordBox.PasswordChanged -= PasswordChanged;
            }

            if ((bool)e.NewValue)
            {
                passwordBox.PasswordChanged += PasswordChanged;
            }
        }

        private static void PasswordChanged(object sender, RoutedEventArgs e)
        {
            PasswordBox passwordBox = sender as PasswordBox;
            if (passwordBox != null)
            {
                SetIsUpdating(passwordBox, true);
                SetPassword(passwordBox, passwordBox.Password);
                SetIsUpdating(passwordBox, false);
            }
        }
    }