Encrypting a dataset using AES, including compression

<Window x:Class="EncryptDataSet.UI.Authentication"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:ui="clr-namespace:EncryptDataSet.UI"
        Title="Authentication" 
        Height="277" 
        Width="300" 
        Loaded="Window_Loaded" 
        Icon="/EncryptDataSet;component/Images/Authentication.png" 
        WindowStartupLocation="CenterOwner" 
        SizeToContent="WidthAndHeight"
        MinWidth="300">
    <Window.Resources>
        <ui:ForegroundConverter x:Key="ForegroundConverter"/>
    </Window.Resources>
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition />
            <RowDefinition Height="Auto"/>
        </Grid.RowDefinitions>
        <StackPanel Grid.Row="0">
            <TextBlock Margin="3" Text="Dataset file name"/>
            <Grid>
                <Grid.ColumnDefinitions>
                    <ColumnDefinition/>
                    <ColumnDefinition Width="Auto"/>
                </Grid.ColumnDefinitions>
                <TextBox Grid.Column="0" Margin="3" Name="txtFileName" IsReadOnly="True" IsTabStop="False" />
                <Button Grid.Column="1" Margin="3" Width="25" Name="btnFile" Click="btnFile_Click" Content="..."/>
            </Grid>
            <TextBlock Margin="3" Text="User name"/>
            <TextBox Margin="3" Name="txtUser"/>
            <TextBlock Margin="3" Text="Password"/>
            <PasswordBox Margin="3" Name="txtPassword" PasswordChanged="txtPassword_PasswordChanged" />
            <TextBlock Margin="3" Name="txtPasswordStrength"  Text="Password strength"/>
            <ProgressBar Margin="3" Name="pbPasswordStrength" Height="20" IsTabStop="False" Value="0" Foreground="{Binding RelativeSource={RelativeSource Mode=Self}, Path=Value, Converter={StaticResource ForegroundConverter}}"/>
        </StackPanel>
        <StackPanel Grid.Row="1" Orientation="Horizontal" HorizontalAlignment="Right">
            <Button Margin="3" Width="70" Name="btnOk" Click="btnOk_Click" Content="Ok" IsDefault="True"/>
            <Button Margin="3" Width="70" Name="btnCancel" Click="btnCancel_Click" Content="Cancel" IsCancel="True"/>
        </StackPanel>
    </Grid>
</Window>