C# / WPF Unmask password inside the passwordBox

How could I unmasked and masked the password inside the passwordBox whenever I click the checkBox? I am using C# WPF template.

Here is my .XAML code:

<PasswordBox x:Name="passwordBox_password" Grid.Row="2" Grid.Column="1" Grid.ColumnSpan="2" Margin="5" Height="25" />
        <CheckBox x:Name="checkBox_showPassword" Grid.Row="3" Grid.Column="1" Margin="5,0,5,5" Content="show password" Checked="checkBox_showPassword_Checked" Unchecked="checkBox_showPassword_Unchecked" />

Here is my .CS code:

private void checkBox_showPassword_Checked(object sender, RoutedEventArgs e)
    {
        // what to do here ?
    }

    private void checkBox_showPassword_Unchecked(object sender, RoutedEventArgs e)
    {
        // what to do here ?
    }

Or is there another way to do it in WPF?