basic support for creating and saving kdbx files.

lib/src/crypto/protected_salt_generator.dart

@@ -11,15 +11,20 @@ class ProtectedSaltGenerator {
     return ProtectedSaltGenerator._(cipher);
   }
 
-  ProtectedSaltGenerator._(this.cipher);
+  ProtectedSaltGenerator._(this._cipher);
 
   static final SalsaNonce = Uint8List.fromList([0xE8, 0x30, 0x09, 0x4B, 0x97, 0x20, 0x5D, 0x2A]);
-  final StreamCipher cipher;
+  final StreamCipher _cipher;
 
   String decryptBase64(String protectedValue) {
     final bytes = base64.decode(protectedValue);
-    final result = cipher.process(bytes);
+    final result = _cipher.process(bytes);
     final decrypted = utf8.decode(result);
     return decrypted;
   }
+
+  String encryptToBase64(String plainValue) {
+    final encrypted = _cipher.process(utf8.encode(plainValue) as Uint8List);
+    return base64.encode(encrypted);
+  }
 }

lib/src/internal/byte_utils.dart

@@ -1,8 +1,14 @@
 import 'dart:ffi';
 import 'dart:io';
+import 'dart:math';
 import 'dart:typed_data';
 
 class ByteUtils {
+  static final _random = Random.secure();
+
+  static Uint8List randomBytes(int length) =>
+      Uint8List.fromList(List.generate(length, (i) => _random.nextInt(1 << 8)));
+
   static bool eq(List<int> a, List<int> b) {
     if (a.length != b.length) {
       return false;
@@ -17,7 +23,8 @@ class ByteUtils {
 
   static String toHex(int val) => '0x${val.toRadixString(16)}';
 
-  static String toHexList(List<int> list) => list.map((val) => toHex(val)).join(' ');
+  static String toHexList(List<int> list) =>
+      list.map((val) => toHex(val)).join(' ');
 }
 
 class ReaderHelper {
@@ -37,11 +44,14 @@ class ReaderHelper {
 
   ByteBuffer readBytes(int size) => _nextByteBuffer(size);
 
+  ByteBuffer readBytesUpTo(int maxSize) =>
+      _nextByteBuffer(min(maxSize, data.lengthInBytes - pos));
+
   Uint8List readRemaining() => data.sublist(pos) as Uint8List;
 }
 
 class WriterHelper {
-  WriterHelper(this.output);
+  WriterHelper([BytesBuilder output]) : output = output ?? BytesBuilder();
 
   final BytesBuilder output;
 
@@ -55,8 +65,12 @@ class WriterHelper {
 //    output.asUint32List().add(value);
   }
 
+  void writeUint64(int value) {
+    output.add(Uint64List.fromList([value]).buffer.asUint8List());
+  }
+
   void writeUint16(int value) {
-    output.add(Uint32List.fromList([value]).buffer.asUint32List());
+    output.add(Uint16List.fromList([value]).buffer.asUint8List());
   }
 
   void writeUint8(int value) {

lib/src/internal/crypto_utils.dart

@@ -67,6 +67,17 @@ class AesHelper {
     return Uint8List(len)..setRange(0, len, src);
   }
 
+  static Uint8List pad(Uint8List src, int blockSize) {
+    final pad = PKCS7Padding();
+    pad.init(null);
+
+    final padLength = blockSize - (src.length % blockSize);
+    final out = Uint8List(src.length + padLength)..setAll(0, src);
+    pad.addPadding(out, src.length);
+
+    return out;
+  }
+
   static Uint8List processBlocks(BlockCipher cipher, Uint8List inp) {
     final out = Uint8List(inp.lengthInBytes);
 

lib/src/kdbx_entry.dart

@@ -6,8 +6,6 @@ import 'package:kdbx/src/kdbx_group.dart';
 import 'package:kdbx/src/kdbx_object.dart';
 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();
@@ -29,7 +27,7 @@ class KdbxEntry extends KdbxObject {
   }
 
   KdbxEntry.read(this.parent, XmlElement node) : super.read(node) {
-    strings.addEntries(node.findElements('String').map((el) {
+    _strings.addEntries(node.findElements('String').map((el) {
       final key = KdbxKey(el.findElements('Key').single.text);
       final valueNode = el.findElements('Value').single;
       if (valueNode.getAttribute('Protected')?.toLowerCase() == 'true') {
@@ -40,11 +38,39 @@ class KdbxEntry extends KdbxObject {
     }));
   }
 
+  XmlElement toXml() {
+    final el = node.copy() as XmlElement;
+    el.children.removeWhere((e) => e is XmlElement && e.name.local == 'String');
+    el.children.addAll(strings.entries.map((stringEntry) {
+      final value = XmlElement(XmlName('Value'));
+      if (stringEntry.value is ProtectedValue) {
+        value.attributes.add(XmlAttribute(XmlName('Protected'), 'true'));
+        KdbxFile.setProtectedValueForNode(
+            value, stringEntry.value as ProtectedValue);
+      } else {
+        value.children.add(XmlText(stringEntry.value.getText()));
+      }
+      return XmlElement(XmlName('String'))
+        ..children.addAll([
+          XmlElement(XmlName('Key'))
+            ..children.add(XmlText(stringEntry.key.key)),
+          value,
+        ]);
+    }));
+    return el;
+  }
+
   KdbxGroup parent;
-  Map<KdbxKey, StringValue> strings = <KdbxKey, StringValue>{};
+  final Map<KdbxKey, StringValue> _strings = {};
+
+  Map<KdbxKey, StringValue> get strings => UnmodifiableMapView(_strings);
+
+  void setString(KdbxKey key, StringValue value) {
+    _strings[key] = value;
+  }
 
   String _plainValue(KdbxKey key) {
-    final value = strings[key];
+    final value = _strings[key];
     if (value is PlainValue) {
       return value.getText();
     }

lib/src/kdbx_format.dart

@@ -43,6 +43,10 @@ class KdbxFile {
     return protectedValues[node];
   }
 
+  static void setProtectedValueForNode(xml.XmlElement node, ProtectedValue value) {
+    protectedValues[node] = value;
+  }
+
   final Credentials credentials;
   final KdbxHeader header;
   final KdbxBody body;
@@ -55,6 +59,7 @@ class KdbxFile {
     body.write(writer, this);
     return output.toBytes();
   }
+
 }
 
 class KdbxBody extends KdbxNode {
@@ -64,7 +69,9 @@ class KdbxBody extends KdbxNode {
     node.children.add(rootNode);
     rootNode.children.add(rootGroup.node);
   }
-  KdbxBody.read(xml.XmlElement node, this.meta, this.rootGroup) : super.read(node);
+
+  KdbxBody.read(xml.XmlElement node, this.meta, this.rootGroup)
+      : super.read(node);
 
 //  final xml.XmlDocument xmlDocument;
   final KdbxMeta meta;
@@ -72,18 +79,63 @@ class KdbxBody extends KdbxNode {
 
   void write(WriterHelper writer, KdbxFile kdbxFile) {
     assert(kdbxFile.header.versionMajor == 3);
-    _writeV3(writer, kdbxFile);
+    final streamKey = kdbxFile
+        .header.fields[HeaderFields.ProtectedStreamKey].bytes
+        .asUint8List();
+    final gen = ProtectedSaltGenerator(streamKey);
+
+    _writeV3(writer, kdbxFile, gen);
   }
 
-  void _writeV3(WriterHelper writer, KdbxFile kdbxFile) {
-    meta.headerHash.set((crypto.sha256.convert(writer.output.toBytes()).bytes as Uint8List).buffer);
+  void _writeV3(WriterHelper writer, KdbxFile kdbxFile,
+      ProtectedSaltGenerator saltGenerator) {
+    meta.headerHash.set(
+        (crypto.sha256.convert(writer.output.toBytes()).bytes as Uint8List)
+            .buffer);
+    final xml = toXml(saltGenerator);
+    final xmlBytes = utf8.encode(xml.toXmlString());
+    final Uint8List compressedBytes = (kdbxFile.header.compression == Compression.gzip ?
+      GZipCodec().encode(xmlBytes) : xmlBytes) as Uint8List;
+
+    final byteWriter = WriterHelper();
+    byteWriter.writeBytes(kdbxFile.header.fields[HeaderFields.StreamStartBytes].bytes.asUint8List());
+    HashedBlockReader.writeBlocks(ReaderHelper(compressedBytes), byteWriter);
+    final bytes = byteWriter.output.toBytes();
+
+    final masterKey = KdbxFormat._generateMasterKeyV3(kdbxFile.header, kdbxFile.credentials);
+    final encrypted = KdbxFormat._encryptDataAes(masterKey, bytes, kdbxFile.header.fields[HeaderFields.EncryptionIV].bytes.asUint8List());
+//    writer.writeBytes(kdbxFile.header.fields[HeaderFields.StreamStartBytes].bytes.asUint8List());
+    writer.writeBytes(encrypted);
   }
 
-  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;
+  xml.XmlDocument toXml(ProtectedSaltGenerator saltGenerator) {
+    final rootGroupNode = rootGroup.toXml();
+    // update protected values...
+    for (final el in rootGroupNode
+        .findAllElements('Value')
+        .where((el) => el.getAttribute('Protected')?.toLowerCase() == 'true')) {
+      final pv = KdbxFile.protectedValues[el];
+      if (pv != null) {
+        final newValue = saltGenerator.encryptToBase64(pv.getText());
+        el.children.clear();
+        el.children.add(xml.XmlText(newValue));
+      } else {
+        _logger.warning('Unable to find protected value for $el ${el.parent}');
+      }
+    }
+
+
+    final builder = xml.XmlBuilder();
+    builder.processing('xml', 'version="1.0" encoding="utf-8" standalone="yes"');
+    builder.element('KeePassFile', nest: [
+      meta.toXml(),
+      () => builder.element('Root', nest: rootGroupNode),],);
+//    final doc = xml.XmlDocument();
+//    doc.children.add(xml.XmlProcessing(
+//        'xml', 'version="1.0" encoding="utf-8" standalone="yes"'));
+    final node = builder.build() as xml.XmlDocument;
+
+    return node;
   }
 }
 
@@ -91,15 +143,19 @@ class KdbxMeta extends KdbxNode {
   KdbxMeta.create({@required String databaseName}) : super.create('Meta') {
     this.databaseName.set(databaseName);
   }
+
   KdbxMeta.read(xml.XmlElement node) : super.read(node);
 
   StringNode get databaseName => StringNode(this, 'DatabaseName');
+
   Base64Node get headerHash => Base64Node(this, 'HeaderHash');
 
+  xml.XmlElement toXml() {
+    return node;
+  }
 }
 
 class KdbxFormat {
-
   static KdbxFile create(Credentials credentials, String name) {
     final header = KdbxHeader.create();
     final meta = KdbxMeta.create(databaseName: name);
@@ -108,7 +164,6 @@ class KdbxFormat {
     return KdbxFile(credentials, header, body);
   }
 
-
   static KdbxFile read(Uint8List input, Credentials credentials) {
     final reader = ReaderHelper(input);
     final header = KdbxHeader.read(reader);
@@ -167,7 +222,8 @@ class KdbxFormat {
     final decryptCipher = CBCBlockCipher(AESFastEngine());
     decryptCipher.init(false,
         ParametersWithIV(KeyParameter(masterKey), encryptionIv.asUint8List()));
-    final decrypted = AesHelper.processBlocks(decryptCipher, encryptedPayload);
+    final paddedDecrypted = AesHelper.processBlocks(decryptCipher, encryptedPayload);
+    final decrypted = paddedDecrypted;//AesHelper.unpad(paddedDecrypted);
 
     final streamStart = header.fields[HeaderFields.StreamStartBytes].bytes;
 
@@ -205,4 +261,12 @@ class KdbxFormat {
         .bytes as Uint8List;
     return masterKey;
   }
+
+  static Uint8List _encryptDataAes(Uint8List masterKey, Uint8List payload, Uint8List encryptionIv) {
+    final encryptCipher = CBCBlockCipher(AESFastEngine());
+    encryptCipher.init(true,
+        ParametersWithIV(KeyParameter(masterKey), encryptionIv));
+    return AesHelper.processBlocks(encryptCipher, AesHelper.pad(payload, encryptCipher.blockSize));
+
+  }
 }

lib/src/kdbx_group.dart

@@ -23,6 +23,15 @@ class KdbxGroup extends KdbxObject {
         .map((el) => KdbxEntry.read(this, el))
         .forEach(_entries.add);
   }
+  
+  XmlElement toXml() {
+    final el = node.copy() as XmlElement;
+    XmlUtils.removeChildrenByName(el, 'Group');
+    XmlUtils.removeChildrenByName(el, 'Entry');
+    el.children.addAll(groups.map((g) => g.toXml()));
+    el.children.addAll(_entries.map((e) => e.toXml()));
+    return el;
+  }
 
   /// Returns all groups plus this group itself.
   List<KdbxGroup> getAllGroups() => groups

lib/src/kdbx_header.dart

@@ -70,8 +70,10 @@ class KdbxHeader {
           fields: _defaultFieldValues(),
         );
 
-  static ByteBuffer _intAsUintBytes(int val) =>
-      Uint8List.fromList([val]).buffer;
+  static ByteBuffer _intAsUint32Bytes(int val) =>
+      (WriterHelper()..writeUint32(val)).output.toBytes().buffer;
+  static ByteBuffer _intAsUint64Bytes(int val) =>
+      (WriterHelper()..writeUint64(val)).output.toBytes().buffer;
 
   static List<HeaderFields> _requiredFields(int majorVersion) {
     if (majorVersion < 3) {
@@ -113,16 +115,18 @@ class KdbxHeader {
 
   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);
+    //      use like [SecureRandom] from PointyCastle?
+    _setHeaderField(HeaderFields.MasterSeed, ByteUtils.randomBytes(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);
+      _setHeaderField(HeaderFields.TransformSeed, ByteUtils.randomBytes(32).buffer);
+      _setHeaderField(
+          HeaderFields.StreamStartBytes, ByteUtils.randomBytes(32).buffer);
+      _setHeaderField(
+          HeaderFields.ProtectedStreamKey, ByteUtils.randomBytes(32).buffer);
+      _setHeaderField(HeaderFields.EncryptionIV, ByteUtils.randomBytes(16).buffer);
     } else {
-      throw KdbxUnsupportedException('We do not support Kdbx 4.x right now. ($versionMajor.$versionMinor)');
+      throw KdbxUnsupportedException(
+          'We do not support Kdbx 4.x right now. ($versionMajor.$versionMinor)');
     }
   }
 
@@ -138,6 +142,7 @@ class KdbxHeader {
         in HeaderFields.values.where((f) => f != HeaderFields.EndOfHeader)) {
       _writeField(writer, field);
     }
+    fields[HeaderFields.EndOfHeader] = HeaderField(HeaderFields.EndOfHeader, Uint8List(0).buffer);
     _writeField(writer, HeaderFields.EndOfHeader);
   }
 
@@ -146,6 +151,8 @@ class KdbxHeader {
     if (value == null) {
       return;
     }
+    _logger.finer('Writing header $field (${value.bytes.lengthInBytes})');
+    writer.writeUint8(field.index);
     _writeFieldSize(writer, value.bytes.lengthInBytes);
     writer.writeBytes(value.bytes.asUint8List());
   }
@@ -162,11 +169,11 @@ class KdbxHeader {
       Map.fromEntries([
         HeaderField(HeaderFields.CipherID,
             CryptoConsts.CIPHER_IDS[Cipher.aes].toBytes()),
-        HeaderField(HeaderFields.CompressionFlags, _intAsUintBytes(1)),
-        HeaderField(HeaderFields.TransformRounds, _intAsUintBytes(6000)),
+        HeaderField(HeaderFields.CompressionFlags, _intAsUint32Bytes(1)),
+        HeaderField(HeaderFields.TransformRounds, _intAsUint64Bytes(6000)),
         HeaderField(
             HeaderFields.InnerRandomStreamID,
-            _intAsUintBytes(ProtectedValueEncryption.values
+            _intAsUint32Bytes(ProtectedValueEncryption.values
                 .indexOf(ProtectedValueEncryption.salsa20))),
       ].map((f) => MapEntry(f.field, f)));
 
@@ -251,13 +258,16 @@ class KdbxUnsupportedException implements KdbxException {
 }
 
 class HashedBlockReader {
+  static const BLOCK_SIZE = 1024 * 1024;
+  static const HASH_SIZE = 32;
+
   static Uint8List readBlocks(ReaderHelper reader) =>
       Uint8List.fromList(readNextBlock(reader).expand((x) => x).toList());
 
   static Iterable<Uint8List> readNextBlock(ReaderHelper reader) sync* {
     while (true) {
       final blockIndex = reader.readUint32();
-      final blockHash = reader.readBytes(32);
+      final blockHash = reader.readBytes(HASH_SIZE);
       final blockSize = reader.readUint32();
       if (blockSize > 0) {
         final blockData = reader.readBytes(blockSize).asUint8List();
@@ -271,4 +281,27 @@ class HashedBlockReader {
       }
     }
   }
+
+//  static Uint8List writeBlocks(WriterHelper writer) =>
+
+  static void writeBlocks(ReaderHelper reader, WriterHelper writer) {
+    while (true) {
+      int blockIndex = 0;
+      final block = reader.readBytesUpTo(BLOCK_SIZE);
+      if (block.lengthInBytes == 0) {
+        // written all data, write a last empty block.
+        writer.writeUint32(blockIndex++);
+        writer.writeBytes(Uint8List.fromList(List.generate(HASH_SIZE, (i) => 0)));
+        writer.writeUint32(0);
+        return;
+      }
+      final blockSize = block.lengthInBytes;
+      final blockHash = crypto.sha256.convert(block.asUint8List());
+      assert(blockHash.bytes.length == HASH_SIZE);
+      writer.writeUint32(blockIndex++);
+      writer.writeBytes(blockHash.bytes as Uint8List);
+      writer.writeUint32(blockSize);
+      writer.writeBytes(block.asUint8List());
+    }
+  }
 }

lib/src/kdbx_object.dart

@@ -3,6 +3,7 @@ import 'dart:typed_data';
 
 import 'package:kdbx/src/kdbx_xml.dart';
 import 'package:uuid/uuid.dart';
+import 'package:uuid/uuid_util.dart';
 import 'package:xml/xml.dart';
 
 class KdbxTimes {
@@ -47,8 +48,12 @@ abstract class KdbxObject extends KdbxNode {
 
 class KdbxUuid {
   const KdbxUuid(this.uuid);
+  KdbxUuid.random() : this(uuidGenerator.v4());
+
+  static final Uuid uuidGenerator = Uuid(options: <String, dynamic>{
+    'grng': UuidUtil.cryptoRNG
+  });
 
-  KdbxUuid.random() : this(Uuid().v4());
 
   /// base64 representation of uuid.
   final String uuid;

lib/src/kdbx_xml.dart

@@ -115,3 +115,9 @@ class BooleanNode extends KdbxSubTextNode<bool> {
   String encode(bool value) => value ? 'true' : 'false';
 
 }
+
+class XmlUtils {
+  static void removeChildrenByName(XmlNode node, String name) {
+    node.children.removeWhere((node) => node is XmlElement && node.name.local == name);
+  }
+}

test/kdbx_test.dart

@@ -2,13 +2,23 @@ import 'dart:io';
 import 'dart:typed_data';
 
 import 'package:kdbx/kdbx.dart';
+import 'package:kdbx/src/crypto/protected_salt_generator.dart';
 import 'package:kdbx/src/crypto/protected_value.dart';
+import 'package:kdbx/src/internal/byte_utils.dart';
 import 'package:kdbx/src/kdbx_format.dart';
-import 'package:kdbx/src/kdbx_header.dart';
 import 'package:logging/logging.dart';
 import 'package:logging_appenders/logging_appenders.dart';
 import 'package:test/test.dart';
 
+class FakeProtectedSaltGenerator implements ProtectedSaltGenerator {
+  @override
+  String decryptBase64(String protectedValue) => 'fake';
+
+  @override
+  String encryptToBase64(String plainValue) => 'fake';
+
+}
+
 void main() {
   Logger.root.level = Level.ALL;
   PrintAppender().attachToLogger(Logger.root);
@@ -28,13 +38,35 @@ void main() {
       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));
+      print(kdbx.body.toXml(FakeProtectedSaltGenerator()).toXmlString(pretty: true));
     });
     test('Create Entry', () {
       final kdbx = KdbxFormat.create(Credentials(ProtectedValue.fromString('FooBar')), 'CreateTest');
       final rootGroup = kdbx.body.rootGroup;
-      rootGroup.addEntry(KdbxEntry.create(rootGroup));
-      print(kdbx.body.toXml().toXmlString(pretty: true));
+      final entry = KdbxEntry.create(rootGroup);
+      rootGroup.addEntry(entry);
+      entry.setString(KdbxKey('Password'), ProtectedValue.fromString('LoremIpsum'));
+      print(kdbx.body.toXml(FakeProtectedSaltGenerator()).toXmlString(pretty: true));
+    });
+  });
+
+  group('Integration', () {
+    test('Simple save and load', () {
+      final credentials = Credentials(ProtectedValue.fromString('FooBar'));
+      Uint8List saved = (() {
+        final kdbx = KdbxFormat.create(credentials, 'CreateTest');
+        final rootGroup = kdbx.body.rootGroup;
+        final entry = KdbxEntry.create(rootGroup);
+        rootGroup.addEntry(entry);
+        entry.setString(
+            KdbxKey('Password'), ProtectedValue.fromString('LoremIpsum'));
+        return kdbx.save();
+      })();
+
+//      print(ByteUtils.toHexList(saved));
+
+      final kdbx = KdbxFormat.read(saved, credentials);
+      expect(kdbx.body.rootGroup.entries.first.strings[KdbxKey('Password')].getText(), 'LoremIpsum');
     });
   });
 }