Datensicherheit: Backup, Verschlüsselung, App-Sperre (Kapitel 13.3)

Automatisches rollierendes Backup der Datenbank beim Start mit Wiederherstellung über die Einstellungen, versionierte Schema-Migration, optionale Passwort-Verschlüsselung der LiteDB-Datei und eine App-Sperre nach Inaktivität mit eigenem Passwort. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
2026-08-13 13:07:36 +02:00
parent db1afff7e4
commit 48d07a2b99
25 changed files with 1228 additions and 21 deletions
@@ -0,0 +1,20 @@
+<Window xmlns="https://github.com/avaloniaui"
+        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+        xmlns:vm="clr-namespace:LehrerApp.Desktop.ViewModels"
+        x:Class="LehrerApp.Desktop.Views.DbPasswordPromptWindow"
+        x:DataType="vm:DbPasswordPromptViewModel"
+        Title="LehrerApp – Datenbank entsperren"
+        Width="360" SizeToContent="Height"
+        CanResize="False" WindowStartupLocation="CenterScreen">
+  <StackPanel Margin="24" Spacing="12">
+    <TextBlock Text="🔒" FontSize="28" HorizontalAlignment="Center"/>
+    <TextBlock Text="Datenbank ist passwortgeschützt" FontSize="15" FontWeight="SemiBold"
+               HorizontalAlignment="Center" TextWrapping="Wrap"/>
+    <TextBox PlaceholderText="Passwort" PasswordChar="●"
+             Text="{Binding Password}" KeyDown="OnKeyDown" x:Name="PasswordBox"/>
+    <TextBlock Text="{Binding Error}" Foreground="Red" FontSize="12" HorizontalAlignment="Center"
+               IsVisible="{Binding Error, Converter={x:Static StringConverters.IsNotNullOrEmpty}}"/>
+    <Button Content="Entsperren" Command="{Binding UnlockCommand}"
+            HorizontalAlignment="Stretch" HorizontalContentAlignment="Center"/>
+  </StackPanel>
+</Window>
@@ -0,0 +1,16 @@
+using Avalonia.Controls;
+using Avalonia.Input;
+using LehrerApp.Desktop.ViewModels;
+
+namespace LehrerApp.Desktop.Views;
+
+public partial class DbPasswordPromptWindow : Window
+{
+    public DbPasswordPromptWindow() => InitializeComponent();
+
+    private void OnKeyDown(object? sender, KeyEventArgs e)
+    {
+        if (e.Key == Key.Enter && DataContext is DbPasswordPromptViewModel vm)
+            vm.UnlockCommand.Execute(null);
+    }
+}
@@ -218,5 +218,26 @@
      </DataTemplate>
    </ItemsControl.ItemTemplate>
  </ItemsControl>
+
+  <!-- App-Sperre nach Inaktivität (13.3.5): blockiert die gesamte Oberfläche. -->
+  <Border Background="#E6101014" IsVisible="{Binding AppLock.IsLocked}">
+    <Border Width="320" Padding="24" CornerRadius="10"
+            Background="{DynamicResource SystemControlBackgroundAltHighBrush}"
+            HorizontalAlignment="Center" VerticalAlignment="Center">
+      <StackPanel Spacing="12">
+        <TextBlock Text="🔒" FontSize="28" HorizontalAlignment="Center"/>
+        <TextBlock Text="LehrerApp gesperrt" FontSize="16" FontWeight="SemiBold"
+                   HorizontalAlignment="Center"/>
+        <TextBox PlaceholderText="Passwort" PasswordChar="●"
+                 Text="{Binding AppLock.PasswordAttempt}"
+                 KeyDown="OnLockScreenKeyDown"/>
+        <TextBlock Text="{Binding AppLock.UnlockError}" Foreground="Red" FontSize="12"
+                   HorizontalAlignment="Center"
+                   IsVisible="{Binding AppLock.UnlockError, Converter={x:Static StringConverters.IsNotNullOrEmpty}}"/>
+        <Button Content="Entsperren" Command="{Binding AppLock.UnlockCommand}"
+                HorizontalAlignment="Stretch" HorizontalContentAlignment="Center"/>
+      </StackPanel>
+    </Border>
+  </Border>
  </Panel>
 </Window>
@@ -1,8 +1,27 @@
 using Avalonia.Controls;
+using Avalonia.Input;
+using LehrerApp.Desktop.ViewModels;

 namespace LehrerApp.Desktop.Views;

 public partial class MainWindow : Window
 {
-    public MainWindow() => InitializeComponent();
+    public MainWindow()
+    {
+        InitializeComponent();
+        PointerMoved   += (_, _) => NotifyActivity();
+        PointerPressed += (_, _) => NotifyActivity();
+        KeyDown        += (_, _) => NotifyActivity();
+    }
+
+    private void NotifyActivity()
+    {
+        if (DataContext is MainWindowViewModel vm) vm.AppLock.NotifyActivity();
+    }
+
+    private void OnLockScreenKeyDown(object? sender, KeyEventArgs e)
+    {
+        if (e.Key == Key.Enter && DataContext is MainWindowViewModel vm)
+            vm.AppLock.UnlockCommand.Execute(null);
+    }
 }
@@ -266,6 +266,118 @@
        </ScrollViewer>
      </ContentPage>

+      <!-- Tab: Sicherheit (13.3) -->
+      <ContentPage Header="Sicherheit">
+        <ScrollViewer>
+          <StackPanel Margin="32,20,32,28" Spacing="24" MaxWidth="560">
+
+            <!-- Datensicherung -->
+            <StackPanel Spacing="10">
+              <TextBlock Text="Datensicherung" FontSize="16" FontWeight="SemiBold"/>
+              <TextBlock Text="Bei jedem Start wird automatisch ein Backup der Datenbank angelegt (die letzten 10 werden behalten)."
+                         FontSize="12" Opacity="0.6" TextWrapping="Wrap"/>
+
+              <Button Content="Jetzt sichern" Command="{Binding CreateBackupNowCommand}"
+                      HorizontalAlignment="Left"/>
+              <TextBlock Text="{Binding BackupStatus}" Foreground="Green" FontSize="12"
+                         IsVisible="{Binding BackupStatus, Converter={x:Static StringConverters.IsNotNullOrEmpty}}"/>
+
+              <ItemsControl ItemsSource="{Binding Backups}">
+                <ItemsControl.ItemTemplate>
+                  <DataTemplate DataType="vm:BackupListItem">
+                    <Border BorderBrush="{DynamicResource SystemControlForegroundBaseLowBrush}"
+                            BorderThickness="0,0,0,1" Padding="0,7">
+                      <Grid ColumnDefinitions="*,Auto">
+                        <TextBlock Grid.Column="0" Text="{Binding Display}"
+                                   VerticalAlignment="Center" FontSize="13"/>
+                        <Button Grid.Column="1" Content="Wiederherstellen" FontSize="12" Padding="10,4"
+                                Command="{Binding $parent[ItemsControl].((vm:SettingsViewModel)DataContext).RestoreBackupCommand}"
+                                CommandParameter="{Binding}"/>
+                      </Grid>
+                    </Border>
+                  </DataTemplate>
+                </ItemsControl.ItemTemplate>
+              </ItemsControl>
+              <TextBlock Text="Noch keine Backups vorhanden." Opacity="0.35" FontSize="12"
+                         IsVisible="{Binding !Backups.Count}"/>
+            </StackPanel>
+
+            <Separator/>
+
+            <!-- Datenbank-Verschlüsselung -->
+            <StackPanel Spacing="10">
+              <TextBlock Text="Datenbank-Verschlüsselung" FontSize="16" FontWeight="SemiBold"/>
+              <TextBlock Text="Schützt die Datenbankdatei auf der Festplatte mit einem Passwort. Ohne das Passwort kann die App die Datenbank beim Start nicht öffnen — bei Verlust sind die Daten nicht mehr zugänglich."
+                         FontSize="12" Opacity="0.6" TextWrapping="Wrap"/>
+              <TextBlock FontSize="13" FontWeight="SemiBold">
+                <Run Text="Status: "/>
+                <Run Text="{Binding DbEncryptionStatusLabel}"/>
+              </TextBlock>
+
+              <StackPanel Spacing="4" IsVisible="{Binding IsDbEncrypted}">
+                <TextBlock Text="Aktuelles Passwort" FontSize="12" Opacity="0.7"/>
+                <TextBox Text="{Binding CurrentDbPassword}" PasswordChar="●"/>
+              </StackPanel>
+
+              <Grid ColumnDefinitions="*,12,*">
+                <StackPanel Grid.Column="0" Spacing="4">
+                  <TextBlock Text="Neues Passwort" FontSize="12" Opacity="0.7"/>
+                  <TextBox Text="{Binding NewDbPassword}" PasswordChar="●"/>
+                </StackPanel>
+                <StackPanel Grid.Column="2" Spacing="4">
+                  <TextBlock Text="Wiederholen" FontSize="12" Opacity="0.7"/>
+                  <TextBox Text="{Binding NewDbPasswordConfirm}" PasswordChar="●"/>
+                </StackPanel>
+              </Grid>
+              <TextBlock Text="{Binding DbPasswordError}" Foreground="Red" FontSize="12"
+                         IsVisible="{Binding DbPasswordError, Converter={x:Static StringConverters.IsNotNullOrEmpty}}"/>
+
+              <StackPanel Orientation="Horizontal" Spacing="8">
+                <Button Content="Passwort speichern" Command="{Binding SaveDbPasswordCommand}"/>
+                <Button Content="Verschlüsselung entfernen" Command="{Binding RemoveDbPasswordCommand}"
+                        IsVisible="{Binding IsDbEncrypted}"/>
+              </StackPanel>
+              <TextBlock Text="Nach dem Ändern wird die App automatisch neu gestartet."
+                         FontSize="11" Opacity="0.5"/>
+            </StackPanel>
+
+            <Separator/>
+
+            <!-- App-Sperre nach Inaktivität -->
+            <StackPanel Spacing="10">
+              <TextBlock Text="App-Sperre nach Inaktivität" FontSize="16" FontWeight="SemiBold"/>
+              <TextBlock Text="Sperrt die Oberfläche nach einer Zeit ohne Maus-/Tastatureingabe. Eigenes Passwort, unabhängig von der Datenbank-Verschlüsselung."
+                         FontSize="12" Opacity="0.6" TextWrapping="Wrap"/>
+
+              <CheckBox Content="App-Sperre aktivieren" IsChecked="{Binding AppLockEnabled}"/>
+
+              <StackPanel Spacing="4" MaxWidth="200">
+                <TextBlock Text="Zeit bis zur Sperre (Minuten)" FontSize="12" Opacity="0.7"/>
+                <NumericUpDown Value="{Binding AppLockTimeoutMinutes}" Minimum="1" Maximum="120" FormatString="0"/>
+              </StackPanel>
+
+              <Grid ColumnDefinitions="*,12,*">
+                <StackPanel Grid.Column="0" Spacing="4">
+                  <TextBlock Text="Passwort (leer lassen, um es zu behalten)" FontSize="12" Opacity="0.7"/>
+                  <TextBox Text="{Binding AppLockNewPassword}" PasswordChar="●"/>
+                </StackPanel>
+                <StackPanel Grid.Column="2" Spacing="4">
+                  <TextBlock Text="Wiederholen" FontSize="12" Opacity="0.7"/>
+                  <TextBox Text="{Binding AppLockNewPasswordConfirm}" PasswordChar="●"/>
+                </StackPanel>
+              </Grid>
+              <TextBlock Text="{Binding AppLockPasswordError}" Foreground="Red" FontSize="12"
+                         IsVisible="{Binding AppLockPasswordError, Converter={x:Static StringConverters.IsNotNullOrEmpty}}"/>
+
+              <Button Content="Speichern" Command="{Binding SaveAppLockSettingsCommand}" HorizontalAlignment="Left"/>
+              <TextBlock Text="{Binding AppLockStatus}" Foreground="Green" FontSize="12"
+                         IsVisible="{Binding AppLockStatus, Converter={x:Static StringConverters.IsNotNullOrEmpty}}"/>
+            </StackPanel>
+
+          </StackPanel>
+        </ScrollViewer>
+      </ContentPage>
+
    </TabbedPage>
  </Grid>
 </UserControl>
@@ -1,7 +1,10 @@
 using Avalonia.Controls;
 using Avalonia.Interactivity;
 using Avalonia.Platform.Storage;
+using LehrerApp.Desktop.ViewModels;
 using LehrerApp.Desktop.ViewModels.Settings;
+using LehrerApp.Desktop.Views.Shared;
+using Microsoft.Extensions.DependencyInjection;

 namespace LehrerApp.Desktop.Views.Settings;

@@ -9,6 +12,30 @@ public partial class SettingsView : UserControl
 {
    public SettingsView() => InitializeComponent();

+    protected override void OnDataContextChanged(EventArgs e)
+    {
+        base.OnDataContextChanged(e);
+        if (DataContext is SettingsViewModel vm)
+        {
+            vm.OnConfirmRestore = ShowRestoreConfirmDialog;
+            vm.OnAppLockChanged = () => App.Services.GetRequiredService<AppLockViewModel>().ApplyConfig();
+        }
+    }
+
+    private async Task<bool> ShowRestoreConfirmDialog(BackupListItem item)
+    {
+        var info = new ConfirmDialogInfo
+        {
+            Title       = "Backup wiederherstellen?",
+            Message     = $"Die aktuelle Datenbank wird durch das Backup vom {item.Display} ersetzt. " +
+                          "Die App wird danach automatisch neu gestartet.",
+            ConfirmText = "Wiederherstellen",
+        };
+        var dialog = new ConfirmDialog { DataContext = info };
+        var owner = TopLevel.GetTopLevel(this) as Window;
+        return owner is not null && await dialog.ShowDialog<bool>(owner);
+    }
+
    private async void OnImportClick(object? sender, RoutedEventArgs e)
    {
        var topLevel = TopLevel.GetTopLevel(this);
@@ -0,0 +1,18 @@
+<Window xmlns="https://github.com/avaloniaui"
+        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+        x:Class="LehrerApp.Desktop.Views.Shared.ConfirmDialog"
+        x:CompileBindings="False"
+        Title="{Binding Title}"
+        Width="420" SizeToContent="Height"
+        CanResize="False" WindowStartupLocation="CenterOwner">
+  <Grid RowDefinitions="*,Auto" Margin="24">
+    <StackPanel Grid.Row="0" Spacing="12">
+      <TextBlock Text="{Binding Title}" FontSize="18" FontWeight="SemiBold"/>
+      <TextBlock Text="{Binding Message}" TextWrapping="Wrap" Opacity="0.8"/>
+    </StackPanel>
+    <Grid Grid.Row="1" ColumnDefinitions="*,8,*" Margin="0,20,0,0">
+      <Button Grid.Column="0" Content="Abbrechen" HorizontalAlignment="Stretch" Click="OnCancel"/>
+      <Button Grid.Column="2" Content="{Binding ConfirmText}" HorizontalAlignment="Stretch" Click="OnConfirm"/>
+    </Grid>
+  </Grid>
+</Window>
@@ -0,0 +1,12 @@
+using Avalonia.Controls;
+using Avalonia.Interactivity;
+
+namespace LehrerApp.Desktop.Views.Shared;
+
+public partial class ConfirmDialog : Window
+{
+    public ConfirmDialog() => InitializeComponent();
+
+    private void OnConfirm(object? sender, RoutedEventArgs e) => Close(true);
+    private void OnCancel(object? sender, RoutedEventArgs e) => Close(false);
+}
@@ -0,0 +1,9 @@
+namespace LehrerApp.Desktop.Views.Shared;
+
+/// Generisches DataContext für <see cref="ConfirmDialog"/>.
+public class ConfirmDialogInfo
+{
+    public string Title       { get; init; } = "";
+    public string Message     { get; init; } = "";
+    public string ConfirmText { get; init; } = "Bestätigen";
+}