diff --git a/bin/kdbx.dart b/bin/kdbx.dart
index a7d119a..aa87460 100644
--- a/bin/kdbx.dart
+++ b/bin/kdbx.dart
@@ -127,6 +127,6 @@ class DumpXmlCommand extends KdbxFileCommand {
 
   @override
   Future<void> runWithFile(KdbxFile file) async {
-    print(file.body.xmlDocument.toXmlString(pretty: true));
+    print(file.body.node.toXmlString(pretty: true));
   }
 }
diff --git a/lib/src/internal/byte_utils.dart b/lib/src/internal/byte_utils.dart
index a625efd..dbcfedd 100644
--- a/lib/src/internal/byte_utils.dart
+++ b/lib/src/internal/byte_utils.dart
@@ -1,3 +1,7 @@
+import 'dart:ffi';
+import 'dart:io';
+import 'dart:typed_data';
+
 class ByteUtils {
   static bool eq(List<int> a, List<int> b) {
     if (a.length != b.length) {
@@ -15,3 +19,47 @@ class ByteUtils {
 
   static String toHexList(List<int> list) => list.map((val) => toHex(val)).join(' ');
 }
+
+class ReaderHelper {
+  ReaderHelper(this.data);
+
+  final Uint8List data;
+  int pos = 0;
+
+  ByteBuffer _nextByteBuffer(int byteCount) =>
+      (data.sublist(pos, pos += byteCount) as Uint8List).buffer;
+
+  int readUint32() => _nextByteBuffer(4).asUint32List().first;
+
+  int readUint16() => _nextByteBuffer(2).asUint16List().first;
+
+  int readUint8() => data[pos++];
+
+  ByteBuffer readBytes(int size) => _nextByteBuffer(size);
+
+  Uint8List readRemaining() => data.sublist(pos) as Uint8List;
+}
+
+class WriterHelper {
+  WriterHelper(this.output);
+
+  final BytesBuilder output;
+
+  void writeBytes(Uint8List bytes) {
+    output.add(bytes);
+//    output.asUint8List().addAll(bytes);
+  }
+
+  void writeUint32(int value) {
+    output.add(Uint32List.fromList([value]).buffer.asUint8List());
+//    output.asUint32List().add(value);
+  }
+
+  void writeUint16(int value) {
+    output.add(Uint32List.fromList([value]).buffer.asUint32List());
+  }
+
+  void writeUint8(int value) {
+    output.addByte(value);
+  }
+}
diff --git a/lib/src/internal/consts.dart b/lib/src/internal/consts.dart
new file mode 100644
index 0000000..7d6128b
--- /dev/null
+++ b/lib/src/internal/consts.dart
@@ -0,0 +1,13 @@
+import 'package:kdbx/src/kdbx_object.dart';
+
+enum Cipher {
+  aes,
+  chaCha20,
+}
+
+class CryptoConsts {
+  static const CIPHER_IDS = <Cipher, KdbxUuid>{
+    Cipher.aes: KdbxUuid('McHy5r9xQ1C+WAUhavxa/w=='),
+    Cipher.chaCha20: KdbxUuid('1gOKK4tvTLWlJDOaMdu1mg=='),
+  };
+}
diff --git a/lib/src/kdbx_entry.dart b/lib/src/kdbx_entry.dart
index 24e2507..c3d72db 100644
--- a/lib/src/kdbx_entry.dart
+++ b/lib/src/kdbx_entry.dart
@@ -7,10 +7,25 @@ import 'package:xml/xml.dart';
 
 String _canonicalizeKey(String key) => key?.toLowerCase();
 
+/// Represents a case insensitive (but case preserving) key.
+class KdbxKey {
+  KdbxKey(this.key) : _canonicalKey = key.toLowerCase();
+
+  final String key;
+  final String _canonicalKey;
+
+  @override
+  bool operator ==(Object other) =>
+      other is KdbxKey && _canonicalKey == other._canonicalKey;
+
+  @override
+  int get hashCode => _canonicalKey.hashCode;
+}
+
 class KdbxEntry extends KdbxObject {
   KdbxEntry.read(this.parent, XmlElement node) : super.read(node) {
     strings.addEntries(node.findElements('String').map((el) {
-      final key = el.findElements('Key').single.text;
+      final key = KdbxKey(el.findElements('Key').single.text);
       final valueNode = el.findElements('Value').single;
       if (valueNode.getAttribute('Protected')?.toLowerCase() == 'true') {
         return MapEntry(key, KdbxFile.protectedValueForNode(valueNode));
@@ -21,10 +36,9 @@ class KdbxEntry extends KdbxObject {
   }
 
   KdbxGroup parent;
-  Map<String, StringValue> strings =
-      CanonicalizedMap<String, String, StringValue>(_canonicalizeKey);
+  Map<KdbxKey, StringValue> strings = <KdbxKey, StringValue>{};
 
-  String _plainValue(String key) {
+  String _plainValue(KdbxKey key) {
     final value = strings[key];
     if (value is PlainValue) {
       return value.getText();
@@ -32,5 +46,5 @@ class KdbxEntry extends KdbxObject {
     return value?.toString();
   }
 
-  String get label => _plainValue('Title');
+  String get label => _plainValue(KdbxKey('Title'));
 }
diff --git a/lib/src/kdbx_format.dart b/lib/src/kdbx_format.dart
index b17b471..55415f6 100644
--- a/lib/src/kdbx_format.dart
+++ b/lib/src/kdbx_format.dart
@@ -10,7 +10,9 @@ import 'package:kdbx/src/internal/byte_utils.dart';
 import 'package:kdbx/src/internal/crypto_utils.dart';
 import 'package:kdbx/src/kdbx_group.dart';
 import 'package:kdbx/src/kdbx_header.dart';
+import 'package:kdbx/src/kdbx_xml.dart';
 import 'package:logging/logging.dart';
+import 'package:meta/meta.dart';
 import 'package:pointycastle/export.dart';
 import 'package:xml/xml.dart' as xml;
 
@@ -44,23 +46,69 @@ class KdbxFile {
   final Credentials credentials;
   final KdbxHeader header;
   final KdbxBody body;
+
+  Uint8List save() {
+    final output = BytesBuilder();
+    final writer = WriterHelper(output);
+    header.generateSalts();
+    header.write(writer);
+    body.write(writer, this);
+    return output.toBytes();
+  }
 }
 
-class KdbxBody {
-  KdbxBody(this.xmlDocument, this.meta, this.rootGroup);
+class KdbxBody extends KdbxNode {
+  KdbxBody.create(this.meta, this.rootGroup) : super.create('KeePassFile') {
+    node.children.add(meta.node);
+    final rootNode = xml.XmlElement(xml.XmlName('Root'));
+    node.children.add(rootNode);
+    rootNode.children.add(rootGroup.node);
+  }
+  KdbxBody.read(xml.XmlElement node, this.meta, this.rootGroup) : super.read(node);
 
-  final xml.XmlDocument xmlDocument;
+//  final xml.XmlDocument xmlDocument;
   final KdbxMeta meta;
   final KdbxGroup rootGroup;
+
+  void write(WriterHelper writer, KdbxFile kdbxFile) {
+    assert(kdbxFile.header.versionMajor == 3);
+    _writeV3(writer, kdbxFile);
+  }
+
+  void _writeV3(WriterHelper writer, KdbxFile kdbxFile) {
+    meta.headerHash.set((crypto.sha256.convert(writer.output.toBytes()).bytes as Uint8List).buffer);
+  }
+
+  xml.XmlDocument toXml() {
+    final doc = xml.XmlDocument();
+    doc.children.add(xml.XmlProcessing('xml', 'version="1.0" encoding="utf-8" standalone="yes"'));
+    doc.children.add(node.copy());
+    return doc;
+  }
 }
 
 class KdbxMeta extends KdbxNode {
+  KdbxMeta.create({@required String databaseName}) : super.create('Meta') {
+    this.databaseName.set(databaseName);
+  }
   KdbxMeta.read(xml.XmlElement node) : super.read(node);
 
-  String get databaseName => text('DatabaseName');
+  StringNode get databaseName => StringNode(this, 'DatabaseName');
+  Base64Node get headerHash => Base64Node(this, 'HeaderHash');
+
 }
 
 class KdbxFormat {
+
+  static KdbxFile create(Credentials credentials, String name) {
+    final header = KdbxHeader.create();
+    final meta = KdbxMeta.create(databaseName: name);
+    final rootGroup = KdbxGroup.create(parent: null, name: name);
+    final body = KdbxBody.create(meta, rootGroup);
+    return KdbxFile(credentials, header, body);
+  }
+
+
   static KdbxFile read(Uint8List input, Credentials credentials) {
     final reader = ReaderHelper(input);
     final header = KdbxHeader.read(reader);
@@ -88,7 +136,7 @@ class KdbxFormat {
 
   static KdbxBody _loadXml(KdbxHeader header, String xmlString) {
     final protectedValueEncryption = header.innerRandomStreamEncryption;
-    if (protectedValueEncryption != PotectedValueEncryption.salsa20) {
+    if (protectedValueEncryption != ProtectedValueEncryption.salsa20) {
       throw KdbxUnsupportedException(
           'Inner encryption: $protectedValueEncryption');
     }
@@ -110,7 +158,7 @@ class KdbxFormat {
     final root = keePassFile.findElements('Root').single;
     final rootGroup = KdbxGroup.read(null, root.findElements('Group').single);
     _logger.fine('got meta: ${meta.toXmlString(pretty: true)}');
-    return KdbxBody(document, KdbxMeta.read(meta), rootGroup);
+    return KdbxBody.read(keePassFile, KdbxMeta.read(meta), rootGroup);
   }
 
   static Uint8List _decryptContent(
diff --git a/lib/src/kdbx_group.dart b/lib/src/kdbx_group.dart
index 93a7288..5678f06 100644
--- a/lib/src/kdbx_group.dart
+++ b/lib/src/kdbx_group.dart
@@ -1,10 +1,14 @@
 import 'package:kdbx/src/kdbx_entry.dart';
+import 'package:kdbx/src/kdbx_xml.dart';
+import 'package:meta/meta.dart';
 import 'package:xml/xml.dart';
 
 import 'kdbx_object.dart';
 
 class KdbxGroup extends KdbxObject {
-  KdbxGroup(this.parent) : super.create('Group');
+  KdbxGroup.create({@required this.parent, @required String name}) : super.create('Group') {
+    this.name.set(name);
+  }
 
   KdbxGroup.read(this.parent, XmlElement node) : super.read(node) {
     node
@@ -31,5 +35,6 @@ class KdbxGroup extends KdbxObject {
   final List<KdbxGroup> groups = [];
   final List<KdbxEntry> entries = [];
 
-  String get name => text('Name') ?? '';
+  StringNode get name => StringNode(this, 'Name');
+//  String get name => text('Name') ?? '';
 }
diff --git a/lib/src/kdbx_header.dart b/lib/src/kdbx_header.dart
index 352493e..2d21a9f 100644
--- a/lib/src/kdbx_header.dart
+++ b/lib/src/kdbx_header.dart
@@ -1,8 +1,12 @@
+import 'dart:math';
 import 'dart:typed_data';
 
 import 'package:crypto/crypto.dart' as crypto;
 import 'package:kdbx/src/internal/byte_utils.dart';
+import 'package:kdbx/src/internal/consts.dart';
 import 'package:logging/logging.dart';
+import 'package:meta/meta.dart';
+import 'package:pointycastle/api.dart';
 
 final _logger = Logger('kdbx.header');
 
@@ -21,7 +25,7 @@ enum Compression {
 }
 
 /// how protected values are encrypted in the xml.
-enum PotectedValueEncryption { plainText, arc4variant, salsa20 }
+enum ProtectedValueEncryption { plainText, arc4variant, salsa20 }
 
 enum HeaderFields {
   EndOfHeader,
@@ -34,7 +38,7 @@ enum HeaderFields {
   EncryptionIV,
   ProtectedStreamKey,
   StreamStartBytes,
-  InnerRandomStreamID,
+  InnerRandomStreamID, // crsAlgorithm
   KdfParameters,
   PublicCustomData,
 }
@@ -49,12 +53,122 @@ class HeaderField {
 }
 
 class KdbxHeader {
-  KdbxHeader(
-      {this.sig1,
-      this.sig2,
-      this.versionMinor,
-      this.versionMajor,
-      this.fields});
+  KdbxHeader({
+    @required this.sig1,
+    @required this.sig2,
+    @required this.versionMinor,
+    @required this.versionMajor,
+    @required this.fields,
+  });
+
+  KdbxHeader.create()
+      : this(
+          sig1: Consts.FileMagic,
+          sig2: Consts.Sig2Kdbx,
+          versionMinor: 1,
+          versionMajor: 3,
+          fields: _defaultFieldValues(),
+        );
+
+  static ByteBuffer _intAsUintBytes(int val) =>
+      Uint8List.fromList([val]).buffer;
+
+  static List<HeaderFields> _requiredFields(int majorVersion) {
+    if (majorVersion < 3) {
+      throw KdbxUnsupportedException('Unsupported version: $majorVersion');
+    }
+    final baseHeaders = [
+      HeaderFields.CipherID,
+      HeaderFields.CompressionFlags,
+      HeaderFields.MasterSeed,
+      HeaderFields.EncryptionIV
+    ];
+    if (majorVersion < 4) {
+      return baseHeaders +
+          [
+            HeaderFields.TransformSeed,
+            HeaderFields.TransformRounds,
+            HeaderFields.ProtectedStreamKey,
+            HeaderFields.StreamStartBytes,
+            HeaderFields.InnerRandomStreamID
+          ];
+    } else {
+      // TODO kdbx 4 support
+      throw KdbxUnsupportedException('We do not support kdbx 4.x right now');
+      return baseHeaders + [HeaderFields.KdfParameters]; // ignore: dead_code
+    }
+  }
+
+  void _validate() {
+    for (HeaderFields required in _requiredFields(versionMajor)) {
+      if (fields[required] == null) {
+        throw KdbxCorruptedFileException('Missing header $required');
+      }
+    }
+  }
+
+  void _setHeaderField(HeaderFields field, ByteBuffer bytes) {
+    fields[field] = HeaderField(field, bytes);
+  }
+
+  void generateSalts() {
+    // TODO make sure default algorithm is "secure" engouh. Or whether we should
+    // use [Random.secure]?
+    final random = SecureRandom();
+    _setHeaderField(HeaderFields.MasterSeed, random.nextBytes(32).buffer);
+    if (versionMajor < 4) {
+      _setHeaderField(HeaderFields.TransformSeed, random.nextBytes(32).buffer);
+      _setHeaderField(HeaderFields.StreamStartBytes, random.nextBytes(32).buffer);
+      _setHeaderField(HeaderFields.ProtectedStreamKey, random.nextBytes(32).buffer);
+      _setHeaderField(HeaderFields.EncryptionIV, random.nextBytes(16).buffer);
+    } else {
+      throw KdbxUnsupportedException('We do not support Kdbx 4.x right now. ($versionMajor.$versionMinor)');
+    }
+  }
+
+  void write(WriterHelper writer) {
+    _validate();
+    // write signature
+    writer.writeUint32(Consts.FileMagic);
+    writer.writeUint32(Consts.Sig2Kdbx);
+    // write version
+    writer.writeUint16(versionMinor);
+    writer.writeUint16(versionMajor);
+    for (final field
+        in HeaderFields.values.where((f) => f != HeaderFields.EndOfHeader)) {
+      _writeField(writer, field);
+    }
+    _writeField(writer, HeaderFields.EndOfHeader);
+  }
+
+  void _writeField(WriterHelper writer, HeaderFields field) {
+    final value = fields[field];
+    if (value == null) {
+      return;
+    }
+    _writeFieldSize(writer, value.bytes.lengthInBytes);
+    writer.writeBytes(value.bytes.asUint8List());
+  }
+
+  void _writeFieldSize(WriterHelper writer, int size) {
+    if (versionMajor >= 4) {
+      writer.writeUint32(size);
+    } else {
+      writer.writeUint16(size);
+    }
+  }
+
+  static Map<HeaderFields, HeaderField> _defaultFieldValues() =>
+      Map.fromEntries([
+        HeaderField(HeaderFields.CipherID,
+            CryptoConsts.CIPHER_IDS[Cipher.aes].toBytes()),
+        HeaderField(HeaderFields.CompressionFlags, _intAsUintBytes(1)),
+        HeaderField(HeaderFields.TransformRounds, _intAsUintBytes(6000)),
+        HeaderField(
+            HeaderFields.InnerRandomStreamID,
+            _intAsUintBytes(ProtectedValueEncryption.values
+                .indexOf(ProtectedValueEncryption.salsa20))),
+      ].map((f) => MapEntry(f.field, f)));
 
   static KdbxHeader read(ReaderHelper reader) {
     // reading signature
@@ -115,8 +229,8 @@ class KdbxHeader {
     }
   }
 
-  PotectedValueEncryption get innerRandomStreamEncryption =>
-      PotectedValueEncryption.values[
+  ProtectedValueEncryption get innerRandomStreamEncryption =>
+      ProtectedValueEncryption.values[
           fields[HeaderFields.InnerRandomStreamID].bytes.asUint32List().single];
 }
 
@@ -124,7 +238,11 @@ class KdbxException implements Exception {}
 
 class KdbxInvalidKeyException implements KdbxException {}
 
-class KdbxCorruptedFileException implements KdbxException {}
+class KdbxCorruptedFileException implements KdbxException {
+  KdbxCorruptedFileException([this.message]);
+
+  final String message;
+}
 
 class KdbxUnsupportedException implements KdbxException {
   KdbxUnsupportedException(this.hint);
@@ -154,23 +272,3 @@ class HashedBlockReader {
     }
   }
 }
-
-class ReaderHelper {
-  ReaderHelper(this.data);
-
-  final Uint8List data;
-  int pos = 0;
-
-  ByteBuffer _nextByteBuffer(int byteCount) =>
-      (data.sublist(pos, pos += byteCount) as Uint8List).buffer;
-
-  int readUint32() => _nextByteBuffer(4).asUint32List().first;
-
-  int readUint16() => _nextByteBuffer(2).asUint16List().first;
-
-  int readUint8() => data[pos++];
-
-  ByteBuffer readBytes(int size) => _nextByteBuffer(size);
-
-  Uint8List readRemaining() => data.sublist(pos) as Uint8List;
-}
diff --git a/lib/src/kdbx_object.dart b/lib/src/kdbx_object.dart
index f92224c..6a7b3d3 100644
--- a/lib/src/kdbx_object.dart
+++ b/lib/src/kdbx_object.dart
@@ -1,4 +1,7 @@
-import 'package:meta/meta.dart';
+import 'dart:convert';
+import 'dart:typed_data';
+
+import 'package:kdbx/src/kdbx_xml.dart';
 import 'package:uuid/uuid.dart';
 import 'package:xml/xml.dart';
 
@@ -15,25 +18,41 @@ class KdbxTimes {
 
 abstract class KdbxNode {
   KdbxNode.create(String nodeName) : node = XmlElement(XmlName(nodeName));
+
   KdbxNode.read(this.node);
 
   final XmlElement node;
 
-  @protected
-  String text(String nodeName) => _opt(nodeName)?.text;
+//  @protected
+//  String text(String nodeName) => _opt(nodeName)?.text;
+
+  KdbxSubTextNode textNode(String nodeName) => StringNode(this, nodeName);
 
-  XmlElement _opt(String nodeName) =>
-      node.findElements(nodeName).singleWhere((x) => true, orElse: () => null);
 }
 
+
 abstract class KdbxObject extends KdbxNode {
   KdbxObject.create(String nodeName)
-      : uuid = Uuid().v4(),
-        super.create(nodeName);
-
-  KdbxObject.read(XmlElement node) : super.read(node) {
-    uuid = node.findElements('UUID').single.text;
+      : super.create(nodeName) {
+    _uuid.set(KdbxUuid.random());
   }
 
-  String uuid;
+  KdbxObject.read(XmlElement node) : super.read(node);
+
+  KdbxUuid get uuid => _uuid.get();
+  UuidNode get _uuid => UuidNode(this, 'UUID');
+}
+
+class KdbxUuid {
+  const KdbxUuid(this.uuid);
+
+  KdbxUuid.random() : this(Uuid().v4());
+
+  /// base64 representation of uuid.
+  final String uuid;
+
+  ByteBuffer toBytes() => base64.decode(uuid).buffer;
+
+  @override
+  String toString() => uuid;
 }
diff --git a/lib/src/kdbx_xml.dart b/lib/src/kdbx_xml.dart
new file mode 100644
index 0000000..ca4a739
--- /dev/null
+++ b/lib/src/kdbx_xml.dart
@@ -0,0 +1,78 @@
+import 'dart:convert';
+import 'dart:typed_data';
+
+import 'package:kdbx/kdbx.dart';
+import 'package:meta/meta.dart';
+import 'package:xml/xml.dart';
+
+abstract class KdbxSubNode<T> {
+  KdbxSubNode(this.node, this.name);
+
+  final KdbxNode node;
+  final String name;
+
+  T get();
+
+  void set(T value);
+}
+
+abstract class KdbxSubTextNode<T> extends KdbxSubNode<T> {
+  KdbxSubTextNode(KdbxNode node, String name) : super(node, name);
+
+  @protected
+  String encode(T value);
+
+  @protected
+  T decode(String value);
+
+  XmlElement _opt(String nodeName) =>
+      node.node.findElements(nodeName).singleWhere((x) => true, orElse: () => null);
+
+  @override
+  T get() {
+    return decode(_opt(name)?.text);
+  }
+
+  @override
+  void set(T value) {
+    final stringValue = encode(value);
+    final el =
+    node.node.findElements(name).singleWhere((x) => true, orElse: () {
+      final el = XmlElement(XmlName(name));
+      node.node.children.add(el);
+      return el;
+    });
+    el.children.clear();
+    el.children.add(XmlText(stringValue));
+  }
+}
+
+class StringNode extends KdbxSubTextNode<String> {
+  StringNode(KdbxNode node, String name) : super(node, name);
+
+  @override
+  String decode(String value) => value;
+
+  @override
+  String encode(String value) => value;
+}
+
+class Base64Node extends KdbxSubTextNode<ByteBuffer> {
+  Base64Node(KdbxNode node, String name) : super(node, name);
+
+  @override
+  ByteBuffer decode(String value) => base64.decode(value).buffer;
+
+  @override
+  String encode(ByteBuffer value) => base64.encode(value.asUint8List());
+}
+
+class UuidNode extends KdbxSubTextNode<KdbxUuid> {
+  UuidNode(KdbxNode node, String name) : super(node, name);
+
+  @override
+  KdbxUuid decode(String value) => KdbxUuid(value);
+
+  @override
+  String encode(KdbxUuid value) => value.uuid;
+}
diff --git a/test/internal/byte_utils_test.dart b/test/internal/byte_utils_test.dart
new file mode 100644
index 0000000..23a0677
--- /dev/null
+++ b/test/internal/byte_utils_test.dart
@@ -0,0 +1,17 @@
+
+import 'dart:io';
+
+import 'package:kdbx/src/internal/byte_utils.dart';
+import 'package:test/test.dart';
+
+void main() {
+  group('WriteHelper', () {
+    test('writing bytes', () {
+      final bytesBuilder = BytesBuilder();
+      final writer = WriterHelper(bytesBuilder);
+      writer.writeUint32(1);
+      print('result: ' + ByteUtils.toHexList(writer.output.toBytes()));
+      expect(writer.output.toBytes(), hasLength(4));
+    });
+  });
+}
diff --git a/test/kdbx_test.dart b/test/kdbx_test.dart
index 1acbcc2..18e2f0b 100644
--- a/test/kdbx_test.dart
+++ b/test/kdbx_test.dart
@@ -12,12 +12,23 @@ import 'package:test/test.dart';
 void main() {
   Logger.root.level = Level.ALL;
   PrintAppender().attachToLogger(Logger.root);
-  group('A group of tests', () {
+  group('Reading', () {
     setUp(() {});
 
     test('First Test', () async {
       final data = await File('test/FooBar.kdbx').readAsBytes() as Uint8List;
-      await KdbxFormat.read(data, Credentials(ProtectedValue.fromString('FooBar')));
+      KdbxFormat.read(data, Credentials(ProtectedValue.fromString('FooBar')));
+    });
+  });
+
+  group('Creating', () {
+    test('Simple create', () {
+      final kdbx = KdbxFormat.create(Credentials(ProtectedValue.fromString('FooBar')), 'CreateTest');
+      expect(kdbx, isNotNull);
+      expect(kdbx.body.rootGroup, isNotNull);
+      expect(kdbx.body.rootGroup.name.get(), 'CreateTest');
+      expect(kdbx.body.meta.databaseName.get(), 'CreateTest');
+      print(kdbx.body.toXml().toXmlString(pretty: true));
     });
   });
 }