How to bind to a PasswordBox in MVVM

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I have come across a problem with binding to a PasswordBox. It seems it's a security risk but I am using the MVVM pattern so I wish to bypass this. I found some interesting code here (has anyone used this or something similar?)

http://www.wpftutorial.net/PasswordBox.html

It technically looks great, but I am unsure of how to retrieve the password.

I basically have properties in my LoginViewModel for Username and Password. Username is fine and is working as it's a TextBox.

I used the code above as stated and entered this

<PasswordBox ff:PasswordHelper.Attach="True"
    ff:PasswordHelper.Password="{Binding Path=Password}" Width="130"/>

When I had the PasswordBox as a TextBox and Binding Path=Password then the property in my LoginViewModel was updated.

My code is very simple, basically I have a Command for my Button. When I press it CanLogin is called and if it returns true it calls Login. You can see I check my property for Username here which works great.

In Login I send along to my service a Username and Password, Username contains data from my View but Password is Null|Empty

private DelegateCommand loginCommand;

    public string Username { get; set; }
    public string Password { get; set; }


    public ICommand LoginCommand
    {
        get
        {
            if (loginCommand == null)
            {
                loginCommand = new DelegateCommand(
                    Login, CanLogin );
            }
            return loginCommand;
        }
    }

    private bool CanLogin()
    {
        return !string.IsNullOrEmpty(Username);
    }

    private void Login()
    {
        bool result = securityService.IsValidLogin(Username, Password);

        if (result) { }
        else { }
    }

This is what I am doing

<TextBox Text="{Binding Path=Username, UpdateSourceTrigger=PropertyChanged}"
         MinWidth="180" />

<PasswordBox ff:PasswordHelper.Attach="True" 
             ff:PasswordHelper.Password="{Binding Path=Password}" Width="130"/>

I have my TextBox, this is no problem, but in my ViewModel the Password is empty.

Am I doing something wrong or missing a step?

I put a breakpoint and sure enough the code enter the static helper class but it never updates my Password in my ViewModel.


Sorry, but you're doing it wrong.

People should have the following security guideline tattooed on the inside of their eyelids: Never keep plain text passwords in memory.

The reason the WPF/Silverlight PasswordBox doesn't expose a DP for the Password property is security related. If WPF/Silverlight were to keep a DP for Password it would require the framework to keep the password itself unencrypted in memory, which is considered quite a troublesome security attack vector.

The PasswordBox uses encrypted memory (of sorts) and the only way to access the password is through the CLR property.

I would suggest that when accessing the PasswordBox.Password CLR property you'd refrain from placing it in any variable or as a value for any property. Keeping your password in plain text on the client machine RAM is a security no-no. So get rid of that public string Password { get; set; } you've got up there.

When accessing PasswordBox.Password, just get it out and ship it to the server ASAP. Don't keep the value of the password around and don't treat it as you would any other client machine text. Don't keep clear text passwords in memory.

I know this breaks the MVVM pattern, but you shouldn't ever bind to PasswordBox.Password Attached DP, store your password in the ViewModel or any other similar shenanigans.

If you're looking for an over-architected solution, here's one:

  1. Create the IHavePassword interface with one method that returns the password clear text.
  2. Have your UserControl implement a IHavePassword interface.
  3. Register the UserControl instance with your IoC as implementing the IHavePassword interface.
  4. When a server request requiring your password is taking place, call your IoC for the IHavePassword implementation and only than get the much coveted password.

Just my take on it.

The PasswordBox control, For this purpose, WPF has the PasswordBox control, which is just as easy to use implemented as a dependency property, which means that you can't bind to it. but for MVVM implementations or if you just love data bindings, a workaround  I know this breaks the MVVM pattern, but you shouldn't ever bind to PasswordBox.Password Attached DP, store your password in the ViewModel or any other similar shenanigans. If you're looking for an over-architected solution, here's one: 1. Create the IHavePassword interface with one method that returns the password clear text. 2.


My 2 cents:

I developed once a typical login dialog (user and password boxes, plus "Ok" button) using WPF and MVVM. I solved the password binding issue by simply passing the PasswordBox control itself as a parameter to the command attached to the "Ok" button. So in the view I had:

<PasswordBox Name="txtPassword" VerticalAlignment="Top" Width="120" />
<Button Content="Ok" Command="{Binding Path=OkCommand}"
   CommandParameter="{Binding ElementName=txtPassword}"/>

And in the ViewModel, the Execute method of the attached command was as follows:

void Execute(object parameter)
{
    var passwordBox = parameter as PasswordBox;
    var password = passwordBox.Password;
    //Now go ahead and check the user name and password
}

This slightly violates the MVVM pattern since now the ViewModel knows something about how the View is implemented, but in that particular project I could afford it. Hope it is useful for someone as well.

How to bind PasswordBox with wpf in MVVM, For security reason WPF didn't gave any Dependency property in Password box. How ever if you really want to achieve what you want then you  Binding to PasswordBox in WPF using MVVM I'm currently working on a Windows Presentation Foundation ( WPF ) client application that adheres to the Model View ViewModel ( MVVM ) design pattern. Having had a lot of experience with .NET WinForms, the WPF learning curve wasn't so steep.


Maybe I am missing something, but it seems like most of these solutions overcomplicate things and do away with secure practices.

This method does not violate the MVVM pattern and maintains complete security. Yes, technically it is code behind, but it is nothing more than a "special case" binding. The ViewModel still has no knowledge of the View implementation, which in my mind it does if you are trying to pass the PasswordBox in to the ViewModel.

Code Behind != Automatic MVVM violation. It all depends on what you do with it. In this case, we are just manually coding a binding, so its all considered part of the UI implementation and therefore is ok.

In the ViewModel, just a simple property. I made it "write only" since there shouldn't be a need to retrieve it from outside the ViewModel for any reason, but it doesn't have to be. Note that it is a SecureString, not just a string.

public SecureString SecurePassword { private get; set; }

In the xaml, you set up a PasswordChanged event handler.

<PasswordBox PasswordChanged="PasswordBox_PasswordChanged"/>

In the code behind:

private void PasswordBox_PasswordChanged(object sender, RoutedEventArgs e)
{
    if (this.DataContext != null)
    { ((dynamic)this.DataContext).SecurePassword = ((PasswordBox)sender).SecurePassword; }
}

With this method, your password remains in a SecureString at all times and therefore provides maximum security. If you really don't care about security or you need the clear text password for a downstream method that requires it (note: most .NET methods that require a password also support a SecureString option, so you may not really need a clear text password even if you think you do), you can just use the Password property instead. Like this:

(ViewModel property)

public string Password { private get; set; }

(Code behind)

private void PasswordBox_PasswordChanged(object sender, RoutedEventArgs e)
{
    if (this.DataContext != null)
    { ((dynamic)this.DataContext).Password = ((PasswordBox)sender).Password; }
}

If you wanted to keep things strongly typed, you could substitute the (dynamic) cast with the interface of your ViewModel. But really, "normal" data bindings aren't strongly typed either, so its not that big a deal.

private void PasswordBox_PasswordChanged(object sender, RoutedEventArgs e)
{
    if (this.DataContext != null)
    { ((IMyViewModel)this.DataContext).Password = ((PasswordBox)sender).Password; }
}

So best of all worlds - your password is secure, your ViewModel just has a property like any other property, and your View is self contained with no external references required.

Security Risk in Binding WPF PasswordBox Password, This article was originally posted here at Programmer's Ranch with the title “C# WPF/MVVM: Why You Shouldn't Bind PasswordBox Password”,  1) Implementation of SecureString type for dependency property instead of String. 2) Binding SecureString type property from ViewModel to PasswordBox's SecurePassword property instead of Password property. 3) Utility method to convert from SecureString to String and vice versa.


You can use this XAML:

<PasswordBox Name="PasswordBox">
    <i:Interaction.Triggers>
        <i:EventTrigger EventName="PasswordChanged">
            <i:InvokeCommandAction Command="{Binding PasswordChangedCommand}" CommandParameter="{Binding ElementName=PasswordBox}"/>
        </i:EventTrigger>
    </i:Interaction.Triggers>
</PasswordBox>

And this command execute method:

private void ExecutePasswordChangedCommand(PasswordBox obj)
{ 
   if (obj != null)
     Password = obj.Password;
}

PasswordBox, The password box control is a special type of TextBox designed to enter passwords. The typed in Databind the Password Property of a WPF PasswordBox. When you Password, which breaks the MVVM PasswordHelper There is an issue with the BindablePasswordBox. It only works in one direction, PasswordBox to PasswordProperty. Below is a modified version of it that works in both directions. It registers a PropertyChangedCallback and updates the PasswordBox's Password when it is called. I hope that someone finds this useful.


This works just fine for me.

<Button Command="{Binding Connect}" 
        CommandParameter="{Binding ElementName=MyPasswordBox}"/>

The “PasswordBox MVVM” dilemma (Part 1), SecurePassword property is not a Dependency Property and hence it cannot be the target of a binding in WPF. This means that you cannot bind it  Get Password from WPF PasswordBox with MVVM in a secure and simple way. Keeping cleartext passwords in memory is a security risk. Therefore the Password and SecurePassword property of WPF PasswordBox is not a DependencyProperty and cannot used for binding. To access the password in the ViewModel in a secure way some work have to be done.


Binding to PasswordBox in WPF using MVVM, Sunday, 17 March 2013. Binding to PasswordBox in WPF using MVVM. I'm currently working on a Windows Presentation Foundation (  How to use the "PasswordBox" control element How to use the ICommand interface.


Get Password from WPF PasswordBox with MVVM in , Get Password from WPF PasswordBox with MVVM in a secure and simple way is not a DependencyProperty and cannot used for binding. The “PasswordBox MVVM” dilemma (Part 1) December 19, 2013 ~ arlvin If you have ever tried to build a WPF application using the MVVM design pattern you will probably have realised that there is a huddle to be overcome when you try to bind the user’s password to a property in the ViewModel.


WPF PasswordBox and Data binding, Now PasswordBox has, as you'd expect, a Password property that .blogspot.​com/2013/03/binding-to-passwordbox-in-wpf-using-mvvm.html. How to bind to a PasswordBox in MVVM (20) . I have come across a problem with binding to a PasswordBox. It seems it's a security risk but I am using the MVVM pattern so I wish to bypass this.