diff --git a/ModernKeePass/App.xaml.cs b/ModernKeePass/App.xaml.cs
index 7d0121f..d905fbc 100644
--- a/ModernKeePass/App.xaml.cs
+++ b/ModernKeePass/App.xaml.cs
@@ -1,20 +1,12 @@
 using System;
-using System.Collections.Generic;
-using System.IO;
-using System.Linq;
-using System.Runtime.InteropServices.WindowsRuntime;
 using Windows.ApplicationModel;
 using Windows.ApplicationModel.Activation;
-using Windows.Foundation;
-using Windows.Foundation.Collections;
 using Windows.UI.Xaml;
 using Windows.UI.Xaml.Controls;
-using Windows.UI.Xaml.Controls.Primitives;
-using Windows.UI.Xaml.Data;
-using Windows.UI.Xaml.Input;
-using Windows.UI.Xaml.Media;
 using Windows.UI.Xaml.Navigation;
 
+using ModernKeePass.Common;
+
 // The Blank Application template is documented at http://go.microsoft.com/fwlink/?LinkId=234227
 
 namespace ModernKeePass
@@ -24,6 +16,7 @@ namespace ModernKeePass
     /// </summary>
     sealed partial class App : Application
     {
+        public DatabaseHelper Database { get; set; }
         /// <summary>
         /// Initializes the singleton application object.  This is the first line of authored code
         /// executed, and as such is the logical equivalent of main() or WinMain().
diff --git a/ModernKeePass/Common/DatabaseHelper.cs b/ModernKeePass/Common/DatabaseHelper.cs
new file mode 100644
index 0000000..6ab1877
--- /dev/null
+++ b/ModernKeePass/Common/DatabaseHelper.cs
@@ -0,0 +1,59 @@
+using System;
+using Windows.Storage;
+using System.Threading.Tasks;
+
+using ModernKeePass.ViewModels;
+using ModernKeePassLib;
+using ModernKeePassLib.Interfaces;
+using ModernKeePassLib.Keys;
+using ModernKeePassLib.Serialization;
+
+namespace ModernKeePass.Common
+{
+    public class DatabaseHelper
+    {
+        private PwDatabase _pwDatabase = new PwDatabase();
+        private StorageFile databaseFile;
+
+        public GroupVm RootGroup { get; set; }
+        public bool IsOpen { get; set; }
+        public string Name { get; set; }
+
+        public DatabaseHelper(StorageFile databaseFile)
+        {
+            this.databaseFile = databaseFile;
+        }
+        public async Task<string> Open(string password)
+        {
+            var key = new CompositeKey();
+            try
+            {
+                key.AddUserKey(new KcpPassword(password));
+                await _pwDatabase.Open(IOConnectionInfo.FromFile(databaseFile), key, new NullStatusLogger());
+                IsOpen = _pwDatabase.IsOpen;
+                Name = databaseFile.DisplayName;
+                RootGroup = new GroupVm(_pwDatabase.RootGroup);
+            }
+            catch (ArgumentNullException)
+            {
+                return "Password cannot be empty";
+            }
+            catch (InvalidCompositeKeyException)
+            {
+                return "Wrong password";
+            }
+            /*finally
+            {
+                // TODO: move this when implementing write mode
+                _pwDatabase.Close();
+            }*/
+            return string.Empty;
+        }
+
+        public void Save()
+        {
+            _pwDatabase.Save(new NullStatusLogger());
+            _pwDatabase.Close();
+        }
+    }
+}
diff --git a/ModernKeePass/MainPage.xaml b/ModernKeePass/MainPage.xaml
index bc4d1f4..dc194d8 100644
--- a/ModernKeePass/MainPage.xaml
+++ b/ModernKeePass/MainPage.xaml
@@ -9,7 +9,7 @@
     mc:Ignorable="d"
     Background="{ThemeResource ApplicationPageBackgroundThemeBrush}" >
     <Page.DataContext>
-        <ViewModels:DatabaseVm/>
+        <ViewModels:HomeVm/>
     </Page.DataContext>
 
     <Grid HorizontalAlignment="Center" VerticalAlignment="Center">
@@ -31,11 +31,13 @@
                 <RowDefinition Height="Auto" />
                 <RowDefinition Height="*" />
                 <RowDefinition Height="*" />
+                <RowDefinition Height="*" />
             </Grid.RowDefinitions>
             <TextBlock Grid.Column="0" Grid.Row="0" x:Name="passwordTextBlock" HorizontalAlignment="Left" TextWrapping="Wrap" Text="Password" VerticalAlignment="Center" Height="auto" Width="auto" FontSize="16" Margin="10,7,0,6" />
             <PasswordBox Grid.Column="1" Grid.Row="0" x:Name="passwordBox" VerticalAlignment="Top" HorizontalAlignment="Right" Width="130" Password="{Binding Password, Mode=TwoWay}" IsPasswordRevealButtonEnabled="True" Margin="0,0,10,0"/>
             <Button Grid.Column="1" Grid.Row="1" x:Name="openBbutton" Content="Open" HorizontalAlignment="Right" VerticalAlignment="Top" Click="openBbutton_Click" Margin="0,0,7,0" Width="auto"/>
             <TextBlock Grid.Column="1" Grid.Row="2" x:Name="errorTextBlock" TextWrapping="Wrap" Text="{Binding ErrorMessage}" HorizontalAlignment="Right" Height="auto" Width="auto" Foreground="#FF9E0909" Margin="0,0,10,0"/>
         </Grid>
+        <Button Grid.Column="1" Grid.Row="3" x:Name="saveBbutton" Content="Save" HorizontalAlignment="Right" VerticalAlignment="Top" Margin="0,0,7,0" Width="auto" Click="saveBbutton_Click"/>
     </Grid>
 </Page>
diff --git a/ModernKeePass/MainPage.xaml.cs b/ModernKeePass/MainPage.xaml.cs
index d7d2302..3ccab12 100644
--- a/ModernKeePass/MainPage.xaml.cs
+++ b/ModernKeePass/MainPage.xaml.cs
@@ -1,6 +1,6 @@
 using System;
+using Windows.UI.Xaml;
 using Windows.UI.Xaml.Controls;
-using Windows.UI.Xaml.Input;
 
 using ModernKeePass.Pages;
 using ModernKeePass.ViewModels;
@@ -19,7 +19,7 @@ namespace ModernKeePass
             this.InitializeComponent();
         }
         
-        private async void Button_Click(object sender, Windows.UI.Xaml.RoutedEventArgs e)
+        private async void Button_Click(object sender, RoutedEventArgs e)
         {
             var picker = new Windows.Storage.Pickers.FileOpenPicker();
             picker.ViewMode = Windows.Storage.Pickers.PickerViewMode.List;
@@ -31,19 +31,31 @@ namespace ModernKeePass
             if (file != null)
             {
                 // Application now has read/write access to the picked file
-                DataContext = new DatabaseVm(file);
-            }
-            else
-            {
+                //DataContext = new DatabaseVm(file);
+                ((App)Application.Current).Database = new Common.DatabaseHelper(file);
+                var homeVm = DataContext as HomeVm;
+                homeVm.Visibility = Visibility.Visible;
+                homeVm.NotifyPropertyChanged("Visibility");
             }
         }
         
-        private void openBbutton_Click(object sender, Windows.UI.Xaml.RoutedEventArgs e)
+        private async void openBbutton_Click(object sender, RoutedEventArgs e)
         {
-            var database = DataContext as DatabaseVm;
+            /*var database = DataContext as DatabaseVm;
             database.Open();
             if (database.IsOpen)
-                Frame.Navigate(typeof(GroupDetailPage), database.RootGroup);
+                Frame.Navigate(typeof(GroupDetailPage), database.RootGroup);*/
+            var homeVm = DataContext as HomeVm;
+            var app = ((App)Application.Current);
+            homeVm.ErrorMessage = await app.Database.Open(homeVm.Password);
+            if (!app.Database.IsOpen) homeVm.NotifyPropertyChanged("ErrorMessage");
+            else Frame.Navigate(typeof(GroupDetailPage), app.Database.RootGroup);
+        }
+
+        private void saveBbutton_Click(object sender, RoutedEventArgs e)
+        {
+            var database = DataContext as HomeVm;
+            ((App)Application.Current).Database.Save();
         }
     }
 }
diff --git a/ModernKeePass/ModernKeePass.csproj b/ModernKeePass/ModernKeePass.csproj
index e3b4b0b..668c41d 100644
--- a/ModernKeePass/ModernKeePass.csproj
+++ b/ModernKeePass/ModernKeePass.csproj
@@ -110,6 +110,7 @@
     <Compile Include="App.xaml.cs">
       <DependentUpon>App.xaml</DependentUpon>
     </Compile>
+    <Compile Include="Common\DatabaseHelper.cs" />
     <Compile Include="Common\NavigationHelper.cs" />
     <Compile Include="Common\ObservableDictionary.cs" />
     <Compile Include="Common\RelayCommand.cs" />
@@ -124,7 +125,7 @@
       <DependentUpon>GroupDetailPage.xaml</DependentUpon>
     </Compile>
     <Compile Include="Properties\AssemblyInfo.cs" />
-    <Compile Include="ViewModels\DatabaseVm.cs" />
+    <Compile Include="ViewModels\HomeVm.cs" />
     <Compile Include="ViewModels\EntryVm.cs" />
     <Compile Include="ViewModels\GroupVm.cs" />
   </ItemGroup>
diff --git a/ModernKeePass/Pages/GroupDetailPage.xaml b/ModernKeePass/Pages/GroupDetailPage.xaml
index 73e5a83..d0f54d1 100644
--- a/ModernKeePass/Pages/GroupDetailPage.xaml
+++ b/ModernKeePass/Pages/GroupDetailPage.xaml
@@ -77,6 +77,8 @@
                             </DataTemplate>
                         </ListView.ItemTemplate>
                     </ListView>
+
+                    <Button x:Name="addGroupButton" VerticalAlignment="Bottom" HorizontalAlignment="Right" Click="addGroupButton_Click" Content="Add Group" />
                 </StackPanel>
             </GridView.Header>
             <GridView.ItemContainerStyle>
diff --git a/ModernKeePass/Pages/GroupDetailPage.xaml.cs b/ModernKeePass/Pages/GroupDetailPage.xaml.cs
index fa2ad71..4f1117c 100644
--- a/ModernKeePass/Pages/GroupDetailPage.xaml.cs
+++ b/ModernKeePass/Pages/GroupDetailPage.xaml.cs
@@ -89,5 +89,11 @@ namespace ModernKeePass.Pages
             var listView = sender as ListView;
             Frame.Navigate(typeof(EntryDetailPage), listView.SelectedItem as EntryVm);
         }
+
+        private void addGroupButton_Click(object sender, Windows.UI.Xaml.RoutedEventArgs e)
+        {
+            var group = DataContext as GroupVm;
+            group.AddGroup("New group");
+        }
     }
 }
diff --git a/ModernKeePass/ViewModels/DatabaseVm.cs b/ModernKeePass/ViewModels/DatabaseVm.cs
deleted file mode 100644
index d5ec026..0000000
--- a/ModernKeePass/ViewModels/DatabaseVm.cs
+++ /dev/null
@@ -1,69 +0,0 @@
-using System.ComponentModel;
-using Windows.Storage;
-
-using ModernKeePassLib;
-using ModernKeePassLib.Keys;
-using ModernKeePassLib.Serialization;
-using ModernKeePassLib.Interfaces;
-using Windows.UI.Xaml;
-using System;
-
-namespace ModernKeePass.ViewModels
-{
-    public class DatabaseVm : INotifyPropertyChanged
-    {
-        private PwDatabase database = new PwDatabase();
-        private StorageFile databaseFile;
-
-        public string Password { get; set; }
-        public bool IsOpen { get; set; }
-        public Visibility Visibility { get; private set; }
-        public string ErrorMessage { get; set; }
-        public string Name { get; set; }
-        public GroupVm RootGroup { get; set; }
-
-
-        public DatabaseVm()
-        {
-            Visibility = Visibility.Collapsed;
-        }
-        public DatabaseVm(StorageFile databaseFile)
-        {
-            this.databaseFile = databaseFile;
-            Visibility = Visibility.Visible;
-        }
-        public async void Open()
-        {
-            var key = new CompositeKey();
-            try
-            {
-                key.AddUserKey(new KcpPassword(Password));
-                await database.Open(IOConnectionInfo.FromFile(databaseFile), key, new NullStatusLogger());
-                IsOpen = database.IsOpen;
-                Name = databaseFile.DisplayName;
-                RootGroup = new GroupVm (database.RootGroup);
-            }
-            catch (ArgumentNullException)
-            {
-                ErrorMessage = "Password cannot be empty";
-                NotifyPropertyChanged("ErrorMessage");
-            }
-            catch (InvalidCompositeKeyException)
-            {
-                ErrorMessage = "Wrong password";
-                NotifyPropertyChanged("ErrorMessage");
-            }
-            finally
-            {
-                // TODO: move this when implementing write mode
-                database.Close();
-            }
-        }
-
-        public event PropertyChangedEventHandler PropertyChanged;
-        public void NotifyPropertyChanged(string propertyName)
-        {
-            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
-        }
-    }
-}
diff --git a/ModernKeePass/ViewModels/GroupVm.cs b/ModernKeePass/ViewModels/GroupVm.cs
index 06a534e..a6ff95a 100644
--- a/ModernKeePass/ViewModels/GroupVm.cs
+++ b/ModernKeePass/ViewModels/GroupVm.cs
@@ -7,6 +7,8 @@ namespace ModernKeePass.ViewModels
 {
     public class GroupVm : INotifyPropertyChanged
     {
+        private PwGroup _pwGroup;
+
         public ObservableCollection<EntryVm> Entries { get; set; }
         public ObservableCollection<GroupVm> Groups { get; set; }
         public string Name { get; set; }
@@ -35,11 +37,23 @@ namespace ModernKeePass.ViewModels
 
         public GroupVm(PwGroup group)
         {
+            _pwGroup = group;
             Name = group.Name;
             Entries = new ObservableCollection<EntryVm>(group.Entries.Select(e => new EntryVm(e)));
             Groups = new ObservableCollection<GroupVm>(group.Groups.Select(g => new GroupVm(g)));
         }
 
+        public void AddGroup(string title)
+        {
+            var pwGroup = new PwGroup
+            {
+                Name = title
+            };
+            Groups.Add(new GroupVm(pwGroup));
+            NotifyPropertyChanged("Groups");
+            this._pwGroup.Groups.Add(pwGroup);
+        }
+
         public event PropertyChangedEventHandler PropertyChanged;
 
         public void NotifyPropertyChanged(string propertyName)
diff --git a/ModernKeePass/ViewModels/HomeVm.cs b/ModernKeePass/ViewModels/HomeVm.cs
new file mode 100644
index 0000000..b473008
--- /dev/null
+++ b/ModernKeePass/ViewModels/HomeVm.cs
@@ -0,0 +1,30 @@
+using System.ComponentModel;
+using Windows.Storage;
+
+using ModernKeePassLib;
+using ModernKeePassLib.Keys;
+using ModernKeePassLib.Serialization;
+using ModernKeePassLib.Interfaces;
+using Windows.UI.Xaml;
+using System;
+
+namespace ModernKeePass.ViewModels
+{
+    public class HomeVm : INotifyPropertyChanged
+    {
+        public string Password { get; set; }
+        public Visibility Visibility { get; set; }
+        public string ErrorMessage { get; set; }
+
+        public HomeVm()
+        {
+            Visibility = Visibility.Collapsed;
+        }
+
+        public event PropertyChangedEventHandler PropertyChanged;
+        public void NotifyPropertyChanged(string propertyName)
+        {
+            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
+        }
+    }
+}
diff --git a/ModernKeePassLib/Cryptography/HashingStreamEx.cs b/ModernKeePassLib/Cryptography/HashingStreamEx.cs
index 7ee615e..40a8dda 100644
--- a/ModernKeePassLib/Cryptography/HashingStreamEx.cs
+++ b/ModernKeePassLib/Cryptography/HashingStreamEx.cs
@@ -20,6 +20,7 @@
 using System;
 using System.Collections.Generic;
 using System.IO;
+using Windows.Security.Cryptography;
 using Windows.Security.Cryptography.Core;
 
 namespace ModernKeePassLib.Cryptography
@@ -29,6 +30,7 @@ namespace ModernKeePassLib.Cryptography
         private Stream m_sBaseStream;
         private bool m_bWriting;
         private Queue<byte[]> m_DataToHash;
+        //private HashAlgorithm m_hash;
 
         public byte[] Hash
         {
@@ -124,9 +126,8 @@ namespace ModernKeePassLib.Cryptography
         {
             m_sBaseStream.Flush();
         }
-
-#if TODO
-		public override void Close()
+        
+		/*public override void Close()
 		{
 
 			if(m_hash != null)
@@ -144,8 +145,7 @@ namespace ModernKeePassLib.Cryptography
 
 			m_sBaseStream.Close();
 
-		}
-#endif
+		}*/
 
         public override long Seek(long lOffset, SeekOrigin soOrigin)
         {
@@ -182,26 +182,22 @@ namespace ModernKeePassLib.Cryptography
 
         public override void Write(byte[] pbBuffer, int nOffset, int nCount)
         {
-            // BERT TODO: Not implemented.
-            Debug.Assert(false);
-#if TODO
 			if(!m_bWriting) throw new InvalidOperationException();
 
 #if DEBUG
 			byte[] pbOrg = new byte[pbBuffer.Length];
 			Array.Copy(pbBuffer, pbOrg, pbBuffer.Length);
 #endif
-
-			if((m_hash != null) && (nCount > 0))
-				m_hash.TransformBlock(pbBuffer, nOffset, nCount, pbBuffer, nOffset);
+            // TODO: implement this
+			/*if((m_hash != null) && (nCount > 0))
+				m_hash.TransformBlock(pbBuffer, nOffset, nCount, pbBuffer, nOffset);*/
 
 #if DEBUG
 			Debug.Assert(MemUtil.ArraysEqual(pbBuffer, pbOrg));
 #endif
 
 			m_sBaseStream.Write(pbBuffer, nOffset, nCount);
-
-#endif // TODO
+            
         }
     }
 }
diff --git a/ModernKeePassLib/Serialization/Kdb4File.Write.cs b/ModernKeePassLib/Serialization/Kdb4File.Write.cs
index bef0d31..2f9586a 100644
--- a/ModernKeePassLib/Serialization/Kdb4File.Write.cs
+++ b/ModernKeePassLib/Serialization/Kdb4File.Write.cs
@@ -19,7 +19,13 @@
 
 using System;
 using System.Collections.Generic;
+using System.Globalization;
 using System.IO;
+using System.IO.Compression;
+using System.Security;
+using System.Text;
+using System.Threading.Tasks;
+using System.Xml;
 //using System.Drawing;
 //using System.Drawing.Imaging;
 
@@ -30,10 +36,13 @@ using ModernKeePassLibSD;
 
 using ModernKeePassLib.Collections;
 using ModernKeePassLib.Cryptography;
+using ModernKeePassLib.Cryptography.Cipher;
 using ModernKeePassLib.Interfaces;
 using ModernKeePassLib.Keys;
+using ModernKeePassLib.Resources;
 using ModernKeePassLib.Security;
 using ModernKeePassLib.Utility;
+using ModernKeePassLib.Delegates;
 
 namespace ModernKeePassLib.Serialization
 {
@@ -62,13 +71,9 @@ namespace ModernKeePassLib.Serialization
 		/// be written.</param>
 		/// <param name="format">Format of the file to create.</param>
 		/// <param name="slLogger">Logger that recieves status information.</param>
-		public void Save(Stream sSaveTo, PwGroup pgDataSource, Kdb4Format format,
+		public async void Save(Stream sSaveTo, PwGroup pgDataSource, Kdb4Format format,
 			IStatusLogger slLogger)
 		{
-                       Debug.Assert(false, "not yet implemented");
-            return;
-#if TODO
-
 			Debug.Assert(sSaveTo != null);
 			if(sSaveTo == null) throw new ArgumentNullException("sSaveTo");
 
@@ -100,7 +105,7 @@ namespace ModernKeePassLib.Serialization
 					bw = new BinaryWriter(hashedStream, encNoBom);
 					WriteHeader(bw); // Also flushes bw
 
-					Stream sEncrypted = AttachStreamEncryptor(hashedStream);
+					Stream sEncrypted = await AttachStreamEncryptor(hashedStream);
 					if((sEncrypted == null) || (sEncrypted == hashedStream))
 						throw new SecurityException(KLRes.CryptoStreamFailed);
 
@@ -117,31 +122,26 @@ namespace ModernKeePassLib.Serialization
 					writerStream = hashedStream;
 				else { Debug.Assert(false); throw new FormatException("KdbFormat"); }
 
-				m_xmlWriter = new XmlTextWriter(writerStream, encNoBom);
-				WriteDocument(pgDataSource);
-
-				m_xmlWriter.Flush();
-				m_xmlWriter.Close();
-				writerStream.Close();
+                using (m_xmlWriter = XmlWriter.Create(writerStream, new XmlWriterSettings { Encoding = encNoBom }))
+                {
+                    WriteDocument(pgDataSource);
 
+                    m_xmlWriter.Flush();
+                    writerStream.Dispose();
+                }
 				GC.KeepAlive(bw);
 			}
 			finally { CommonCleanUpWrite(sSaveTo, hashedStream); }
-#endif
 		}
 
 		private void CommonCleanUpWrite(Stream sSaveTo, HashingStreamEx hashedStream)
 		{
-             Debug.Assert(false, "not yet implemented");
-            return;
-#if TODO
-			hashedStream.Close();
+			//hashedStream.Close();
 			m_pbHashOfFileOnDisk = hashedStream.Hash;
 
-			sSaveTo.Close();
+			sSaveTo.Dispose();
 
 			m_xmlWriter = null;
-#endif
 		}
 
 		private void WriteHeader(BinaryWriter bw)
@@ -193,47 +193,41 @@ namespace ModernKeePassLib.Serialization
 			else bwOut.Write((ushort)0);
 		}
 
-		private Stream AttachStreamEncryptor(Stream s)
+		private async Task<Stream> AttachStreamEncryptor(Stream s)
 		{
-                       Debug.Assert(false, "not yet implemented");
-            return null;
-#if TODO
-			MemoryStream ms = new MemoryStream();
+            using (MemoryStream ms = new MemoryStream())
+            {
 
-			Debug.Assert(m_pbMasterSeed != null);
-			Debug.Assert(m_pbMasterSeed.Length == 32);
-			ms.Write(m_pbMasterSeed, 0, 32);
+                Debug.Assert(m_pbMasterSeed != null);
+                Debug.Assert(m_pbMasterSeed.Length == 32);
+                ms.Write(m_pbMasterSeed, 0, 32);
 
-			Debug.Assert(m_pwDatabase != null);
-			Debug.Assert(m_pwDatabase.MasterKey != null);
-			ProtectedBinary pbinKey = m_pwDatabase.MasterKey.GenerateKey32(
-				m_pbTransformSeed, m_pwDatabase.KeyEncryptionRounds);
-			Debug.Assert(pbinKey != null);
-			if(pbinKey == null)
-				throw new SecurityException(KLRes.InvalidCompositeKey);
-			byte[] pKey32 = pbinKey.ReadData();
-			if((pKey32 == null) || (pKey32.Length != 32))
-				throw new SecurityException(KLRes.InvalidCompositeKey);
-			ms.Write(pKey32, 0, 32);
+                Debug.Assert(m_pwDatabase != null);
+                Debug.Assert(m_pwDatabase.MasterKey != null);
+                ProtectedBinary pbinKey = await m_pwDatabase.MasterKey.GenerateKey32(
+                    m_pbTransformSeed, m_pwDatabase.KeyEncryptionRounds);
+                Debug.Assert(pbinKey != null);
+                if (pbinKey == null)
+                    throw new SecurityException(KLRes.InvalidCompositeKey);
+                byte[] pKey32 = pbinKey.ReadData();
+                if ((pKey32 == null) || (pKey32.Length != 32))
+                    throw new SecurityException(KLRes.InvalidCompositeKey);
+                ms.Write(pKey32, 0, 32);
 
-			SHA256Managed sha256 = new SHA256Managed();
-			byte[] aesKey = sha256.ComputeHash(ms.ToArray());
-			
-			ms.Close();
-			Array.Clear(pKey32, 0, 32);
+                SHA256Managed sha256 = SHA256Managed.Instance;
+                byte[] aesKey = sha256.ComputeHash(ms.ToArray());
+                
+			    Array.Clear(pKey32, 0, 32);
 
-			Debug.Assert(CipherPool.GlobalPool != null);
-			ICipherEngine iEngine = CipherPool.GlobalPool.GetCipher(m_pwDatabase.DataCipherUuid);
-			if(iEngine == null) throw new SecurityException(KLRes.FileUnknownCipher);
-			return iEngine.EncryptStream(s, aesKey, m_pbEncryptionIV);
-#endif
+			    Debug.Assert(CipherPool.GlobalPool != null);
+			    ICipherEngine iEngine = CipherPool.GlobalPool.GetCipher(m_pwDatabase.DataCipherUuid);
+			    if(iEngine == null) throw new SecurityException(KLRes.FileUnknownCipher);
+			    return iEngine.EncryptStream(s, aesKey, m_pbEncryptionIV);
+            }
 		}
 
 		private void WriteDocument(PwGroup pgDataSource)
 		{
-                       Debug.Assert(false, "not yet implemented");
-            return;
-#if TODO
 			Debug.Assert(m_xmlWriter != null);
 			if(m_xmlWriter == null) throw new InvalidOperationException();
 
@@ -244,9 +238,8 @@ namespace ModernKeePassLib.Serialization
 
 			BinPoolBuild(pgRoot);
 
-			m_xmlWriter.Formatting = Formatting.Indented;
-			m_xmlWriter.IndentChar = '\t';
-			m_xmlWriter.Indentation = 1;
+			m_xmlWriter.Settings.Indent = true;
+			m_xmlWriter.Settings.IndentChars = "\t";
 
 			m_xmlWriter.WriteStartDocument(true);
 			m_xmlWriter.WriteStartElement(ElemDocNode);
@@ -313,7 +306,6 @@ namespace ModernKeePassLib.Serialization
 
 			m_xmlWriter.WriteEndElement(); // ElemDocNode
 			m_xmlWriter.WriteEndDocument();
-#endif
 		}
 
 		private void WriteMeta()
@@ -380,9 +372,6 @@ namespace ModernKeePassLib.Serialization
 
 		private void WriteEntry(PwEntry pe, bool bIsHistory)
 		{
-                       Debug.Assert(false, "not yet implemented");
-            return;
-#if TODO
 			Debug.Assert(pe != null); if(pe == null) throw new ArgumentNullException("pe");
 
 			m_xmlWriter.WriteStartElement(ElemEntry);
@@ -408,7 +397,6 @@ namespace ModernKeePassLib.Serialization
 			else { Debug.Assert(pe.History.UCount == 0); }
 
 			m_xmlWriter.WriteEndElement();
-#endif
 		}
 
 		private void WriteList(ProtectedStringDictionary dictStrings, bool bEntryStrings)
@@ -635,10 +623,6 @@ namespace ModernKeePassLib.Serialization
 
 		private void WriteObject(string name, ProtectedString value, bool bIsEntryString)
 		{
-                Debug.Assert(false, "not yet implemented");
-            return;
-#if TODO
-
 			Debug.Assert(name != null);
 			Debug.Assert(value != null); if(value == null) throw new ArgumentNullException("value");
 
@@ -694,7 +678,7 @@ namespace ModernKeePassLib.Serialization
 						// page area
 						if(char.IsSymbol(ch) || char.IsSurrogate(ch))
 						{
-							System.Globalization.UnicodeCategory cat = char.GetUnicodeCategory(ch);
+							UnicodeCategory cat = CharUnicodeInfo.GetUnicodeCategory(ch);
 							// Map character to correct position in code page
 							chMapped = (char)((int)cat * 32 + ch);
 						}
@@ -706,7 +690,7 @@ namespace ModernKeePassLib.Serialization
 								// in the low ANSI range (up to 255) when calling
 								// ToLower on them with invariant culture (see
 								// http://lists.ximian.com/pipermail/mono-patches/2002-February/086106.html )
-								chMapped = char.ToLower(ch, CultureInfo.InvariantCulture);
+								chMapped = char.ToLowerInvariant(ch);
 							}
 						}
 
@@ -725,7 +709,6 @@ namespace ModernKeePassLib.Serialization
 
 			m_xmlWriter.WriteEndElement(); // ElemValue
 			m_xmlWriter.WriteEndElement(); // ElemString
-#endif
         }
 
 		private void WriteObject(string name, ProtectedBinary value, bool bAllowRef)
@@ -752,10 +735,6 @@ namespace ModernKeePassLib.Serialization
 
 		private void SubWriteValue(ProtectedBinary value)
 		{
-
-            Debug.Assert(false, "not yet implemented");
-            return ;
-#if TODO
 			if(value.IsProtected && (m_format != Kdb4Format.PlainXml))
 			{
 				m_xmlWriter.WriteAttributeString(AttrProtected, ValTrue);
@@ -780,7 +759,6 @@ namespace ModernKeePassLib.Serialization
 					m_xmlWriter.WriteBase64(pbRaw, 0, pbRaw.Length);
 				}
 			}
-#endif
 		}
 
 		private void WriteObject(string name, PwDeletedObject value)
diff --git a/ModernKeePassLib/project.json b/ModernKeePassLib/project.json
index 36d3363..754f7fe 100644
--- a/ModernKeePassLib/project.json
+++ b/ModernKeePassLib/project.json
@@ -5,6 +5,7 @@
     "NETStandard.Library": "2.0.0",
     "System.Net.Requests": "4.3.0",
     "System.Runtime.WindowsRuntime": "4.3.0",
+    "System.Xml.ReaderWriter": "4.3.0",
     "System.Xml.XmlSerializer": "4.3.0"
   },
   "frameworks": {
diff --git a/ModernKeePassLib/project.lock.json b/ModernKeePassLib/project.lock.json
index e9f5229..6d3363c 100644
--- a/ModernKeePassLib/project.lock.json
+++ b/ModernKeePassLib/project.lock.json
@@ -2988,6 +2988,7 @@
       "NETStandard.Library >= 2.0.0",
       "System.Net.Requests >= 4.3.0",
       "System.Runtime.WindowsRuntime >= 4.3.0",
+      "System.Xml.ReaderWriter >= 4.3.0",
       "System.Xml.XmlSerializer >= 4.3.0"
     ],
     ".NETStandard,Version=v1.2": []