diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7b6c8f9..a101742 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+## 0.3.0+1
+
+- Minor fixes for kdbx 4.x
+
 ## 0.3.0
 
 - Initial support for kdbx 4.x
diff --git a/lib/kdbx.dart b/lib/kdbx.dart
index b5a9c2d..20d45d6 100644
--- a/lib/kdbx.dart
+++ b/lib/kdbx.dart
@@ -1,6 +1,7 @@
 /// dart library for reading keepass file format (kdbx).
 library kdbx;
 
+export 'src/crypto/key_encrypter_kdf.dart' show Argon2;
 export 'src/crypto/protected_value.dart'
     show ProtectedValue, StringValue, PlainValue;
 export 'src/kdbx_consts.dart';
@@ -9,7 +10,6 @@ export 'src/kdbx_dao.dart' show KdbxDao;
 export 'src/kdbx_entry.dart';
 export 'src/kdbx_format.dart';
 export 'src/kdbx_group.dart';
-export 'src/crypto/key_encrypter_kdf.dart' show Argon2;
 export 'src/kdbx_header.dart'
     show
         KdbxException,
diff --git a/lib/src/crypto/key_encrypter_kdf.dart b/lib/src/crypto/key_encrypter_kdf.dart
index 9a98e6a..e294bb2 100644
--- a/lib/src/crypto/key_encrypter_kdf.dart
+++ b/lib/src/crypto/key_encrypter_kdf.dart
@@ -67,7 +67,7 @@ class KeyEncrypterKdf {
     'ydnzmmKKRGC/dA0IwYpP6g==': KdfType.Aes,
   };
   static KdbxUuid kdfUuidForType(KdfType type) {
-    String uuid =
+    final uuid =
         kdfUuids.entries.firstWhere((element) => element.value == type).key;
     return KdbxUuid(uuid);
   }
@@ -99,7 +99,8 @@ class KeyEncrypterKdf {
     return argon2.argon2(
       key,
       KdfField.salt.read(kdfParameters),
-      65536, //KdfField.memory.read(kdfParameters),
+//      65536, //KdfField.memory.read(kdfParameters),
+      KdfField.memory.read(kdfParameters) ~/ 1024,
       KdfField.iterations.read(kdfParameters),
       32,
       KdfField.parallelism.read(kdfParameters),
diff --git a/lib/src/crypto/protected_salt_generator.dart b/lib/src/crypto/protected_salt_generator.dart
index b63f5bb..e788d2b 100644
--- a/lib/src/crypto/protected_salt_generator.dart
+++ b/lib/src/crypto/protected_salt_generator.dart
@@ -1,10 +1,13 @@
 import 'dart:convert';
 import 'dart:typed_data';
 
+import 'package:logging/logging.dart';
 import 'package:crypto/crypto.dart';
 import 'package:cryptography/cryptography.dart' as cryptography;
 import 'package:pointycastle/export.dart';
 
+final _logger = Logger('protected_salt_generator');
+
 class ProtectedSaltGenerator {
   factory ProtectedSaltGenerator(Uint8List key) {
     final hash = sha256.convert(key).bytes as Uint8List;
@@ -24,6 +27,10 @@ class ProtectedSaltGenerator {
 
   String decryptBase64(String protectedValue) {
     final bytes = base64.decode(protectedValue);
+    if (bytes.isEmpty) {
+      _logger.warning('decoded base64 data has length 0');
+      return null;
+    }
     final result = _cipher.process(bytes);
     final decrypted = utf8.decode(result);
     return decrypted;
@@ -36,34 +43,54 @@ class ProtectedSaltGenerator {
 }
 
 class ChachaProtectedSaltGenerator implements ProtectedSaltGenerator {
-  ChachaProtectedSaltGenerator._(this._secretKey, this._nonce);
+  ChachaProtectedSaltGenerator._(this._secretKey, this._nonce, this._state);
 
   factory ChachaProtectedSaltGenerator.create(Uint8List key) {
     final hash = sha512.convert(key);
     final secretKey = hash.bytes.sublist(0, 32);
     final nonce = hash.bytes.sublist(32, 32 + 12);
+
     return ChachaProtectedSaltGenerator._(
-        cryptography.SecretKey(secretKey), cryptography.SecretKey(nonce));
+        cryptography.SecretKey(secretKey),
+        cryptography.SecretKey(nonce),
+        cryptography.chacha20.newState(cryptography.SecretKey(secretKey),
+            nonce: cryptography.SecretKey(nonce)));
   }
 
   final cryptography.SecretKey _secretKey;
   final cryptography.SecretKey _nonce;
+  final cryptography.KeyStreamCipherState _state;
 
   @override
   StreamCipher get _cipher => throw UnimplementedError();
 
   @override
   String decryptBase64(String protectedValue) {
-    final result = cryptography.chacha20
-        .decrypt(base64.decode(protectedValue), _secretKey, nonce: _nonce);
-    return utf8.decode(result);
+    final bytes = base64.decode(protectedValue);
+    if (bytes.isEmpty) {
+      _logger.warning('decoded base64 data has length 0');
+      return null;
+    }
+    final result = _state.convert(bytes);
+//    try {
+    _logger.fine('decoding protected value.');
+    final ret = utf8.decode(result);
+    _logger.fine('Successfully decoded stuff.');
+    return ret;
+//    } on FormatException catch (e, stackTrace) {
+//      final ret = utf8.decode(result, allowMalformed: true);
+//      _logger.severe(
+//          'Error while decoding utf8. ignoring malformed. result: {$ret}',
+//          e,
+//          stackTrace);
+//      return ret;
+//    }
   }
 
   @override
   String encryptToBase64(String plainValue) {
     final input = utf8.encode(plainValue) as Uint8List;
-    final encrypted =
-        cryptography.chacha20.encrypt(input, _secretKey, nonce: _nonce);
+    final encrypted = _state.convert(input);
     return base64.encode(encrypted);
   }
 }
diff --git a/lib/src/kdbx_format.dart b/lib/src/kdbx_format.dart
index cd41715..58293ca 100644
--- a/lib/src/kdbx_format.dart
+++ b/lib/src/kdbx_format.dart
@@ -1,6 +1,5 @@
 import 'dart:async';
 import 'dart:convert';
-import 'dart:ffi';
 import 'dart:io';
 import 'dart:typed_data';
 
@@ -282,6 +281,8 @@ class KdbxBody extends KdbxNode {
       return result;
     } else if (cipherId == CryptoConsts.CIPHER_IDS[Cipher.chaCha20].uuid) {
       _logger.fine('We need chacha20');
+      // TODO can we combine this with _encryptV3?
+      throw UnsupportedError('Unsupported cipher chacha20 for kdbx 4.x');
     } else {
       throw UnsupportedError('Unsupported cipherId $cipherId');
     }
@@ -405,16 +406,16 @@ class KdbxFormat {
     final headerHmac =
         _getHeaderHmac(reader.byteData.sublist(0, header.endPos), keys.hmacKey);
     final expectedHmac = reader.readBytes(headerHmac.bytes.length);
-//    _logger.fine('Expected: ${ByteUtils.toHexList(expectedHmac)}');
-//    _logger.fine('Actual  : ${ByteUtils.toHexList(headerHmac.bytes)}');
-    if (!ByteUtils.eq(hash, actualHash)) {
+    _logger.fine('Expected: ${ByteUtils.toHexList(expectedHmac)}');
+    _logger.fine('Actual  : ${ByteUtils.toHexList(headerHmac.bytes)}');
+    if (!ByteUtils.eq(headerHmac.bytes, expectedHmac)) {
       throw KdbxInvalidKeyException();
     }
 //    final hmacTransformer = crypto.Hmac(crypto.sha256, hmacKey.bytes);
 //    final blockreader.readBytes(32);
-    final bodyStuff = hmacBlockTransformer(reader);
-    _logger.fine('body decrypt: ${ByteUtils.toHexList(bodyStuff)}');
-    final decrypted = decrypt(header, bodyStuff, keys.cipherKey);
+    final bodyContent = hmacBlockTransformer(reader);
+    _logger.fine('body decrypt: ${ByteUtils.toHexList(bodyContent)}');
+    final decrypted = decrypt(header, bodyContent, keys.cipherKey);
     _logger.finer('compression: ${header.compression}');
     if (header.compression == Compression.gzip) {
       final content = GZipCodec().decode(decrypted) as Uint8List;
@@ -431,7 +432,7 @@ class KdbxFormat {
   Uint8List hmacBlockTransformer(ReaderHelper reader) {
     Uint8List blockHash;
     int blockLength;
-    List<int> ret = <int>[];
+    final ret = <int>[];
     while (true) {
       blockHash = reader.readBytes(32);
       blockLength = reader.readUint32();
diff --git a/lib/src/kdbx_xml.dart b/lib/src/kdbx_xml.dart
index 38c2435..690b427 100644
--- a/lib/src/kdbx_xml.dart
+++ b/lib/src/kdbx_xml.dart
@@ -3,6 +3,7 @@ import 'dart:typed_data';
 
 import 'package:clock/clock.dart';
 import 'package:kdbx/kdbx.dart';
+import 'package:kdbx/src/internal/byte_utils.dart';
 import 'package:kdbx/src/kdbx_consts.dart';
 import 'package:meta/meta.dart';
 import 'package:xml/xml.dart';
@@ -154,7 +155,23 @@ class DateTimeUtcNode extends KdbxSubTextNode<DateTime> {
   }
 
   @override
-  DateTime decode(String value) => DateTime.parse(value);
+  DateTime decode(String value) {
+    if (value == null) {
+      return null;
+    }
+    if (value.contains(':')) {
+      return DateTime.parse(value);
+    }
+    // kdbx 4.x uses base64 encoded date.
+    final decoded = base64.decode(value);
+    const EpochSeconds = 62135596800;
+
+    final secondsFrom00 = ReaderHelper(decoded).readUint64();
+
+    return DateTime.fromMillisecondsSinceEpoch(
+        (secondsFrom00 - EpochSeconds) * 1000,
+        isUtc: true);
+  }
 
   @override
   String encode(DateTime value) {
diff --git a/test/kdbx4_test.dart b/test/kdbx4_test.dart
index 283c179..baf4306 100644
--- a/test/kdbx4_test.dart
+++ b/test/kdbx4_test.dart
@@ -13,6 +13,8 @@ import 'package:test/test.dart';
 
 final _logger = Logger('kdbx4_test');
 
+// ignore_for_file: non_constant_identifier_names
+
 //typedef HashStuff = Pointer<Utf8> Function(Pointer<Utf8> str);
 typedef Argon2HashNative = Pointer<Utf8> Function(
   Pointer<Uint8> key,
@@ -100,7 +102,6 @@ void main() {
   PrintAppender().attachToLogger(Logger.root);
   final kdbxFormat = KdbxFormat(Argon2Test());
   group('Reading', () {
-    final argon2 = Argon2Test();
     test('bubb', () async {
       final key = utf8.encode('asdf') as Uint8List;
       final salt = Uint8List(8);
@@ -126,6 +127,7 @@ void main() {
       final saved = kdbx.save();
 
       final loadedKdbx = kdbxFormat.read(saved, credentials);
+      _logger.fine('Successfully loaded kdbx $loadedKdbx');
       File('test_v4.kdbx').writeAsBytesSync(saved);
     });
   });