improve nnbd, add debugging to aes decryption

CHANGELOG.md

@@ -1,3 +1,8 @@
+## 2.0.0+1
+
+- Small Null-safety improvement.
+- add debugging to AES decryption.
+
 ## 2.0.0
 
 - Null-safety migration

lib/src/kdbx_format.dart

@@ -265,14 +265,14 @@ class KdbxBody extends KdbxNode {
       KdbxFile kdbxFile, Uint8List? compressedBytes) async {
     final byteWriter = WriterHelper();
     byteWriter.writeBytes(
-        kdbxFile.header.fields[HeaderFields.StreamStartBytes]!.bytes!);
+        kdbxFile.header.fields[HeaderFields.StreamStartBytes]!.bytes);
     HashedBlockReader.writeBlocks(ReaderHelper(compressedBytes), byteWriter);
     final bytes = byteWriter.output.toBytes();
 
     final masterKey = await KdbxFormat._generateMasterKeyV3(
         kdbxFile.header, kdbxFile.credentials);
     final encrypted = KdbxFormat._encryptDataAes(masterKey, bytes,
-        kdbxFile.header.fields[HeaderFields.EncryptionIV]!.bytes!);
+        kdbxFile.header.fields[HeaderFields.EncryptionIV]!.bytes);
     return encrypted;
   }
 
@@ -537,7 +537,7 @@ class KdbxFormat {
       throw UnsupportedError('Unsupported version ${header.version}');
     } else if (file.header.version < KdbxVersion.V4) {
       final streamKey =
-          file.header.fields[HeaderFields.ProtectedStreamKey]!.bytes!;
+          file.header.fields[HeaderFields.ProtectedStreamKey]!.bytes;
       final gen = ProtectedSaltGenerator(streamKey);
 
       body.meta.headerHash.set(headerHash.buffer);
@@ -703,7 +703,7 @@ class KdbxFormat {
 
   Uint8List transformContentV4ChaCha20(
       KdbxHeader header, Uint8List encrypted, Uint8List cipherKey) {
-    final encryptionIv = header.fields[HeaderFields.EncryptionIV]!.bytes!;
+    final encryptionIv = header.fields[HeaderFields.EncryptionIV]!.bytes;
     final chaCha = ChaCha7539Engine()
       ..init(true, ParametersWithIV(KeyParameter(cipherKey), encryptionIv));
     return chaCha.process(encrypted);
@@ -726,7 +726,7 @@ class KdbxFormat {
 
   Future<_KeysV4> _computeKeysV4(
       KdbxHeader header, Credentials credentials) async {
-    final masterSeed = header.fields[HeaderFields.MasterSeed]!.bytes!;
+    final masterSeed = header.fields[HeaderFields.MasterSeed]!.bytes;
     final kdfParameters = header.readKdfParameters;
     if (masterSeed.length != 32) {
       throw const FormatException('Master seed must be 32 bytes.');
@@ -823,14 +823,16 @@ class KdbxFormat {
 
   Uint8List _decryptContent(
       KdbxHeader header, Uint8List masterKey, Uint8List encryptedPayload) {
-    final encryptionIv = header.fields[HeaderFields.EncryptionIV]!.bytes!;
+    final encryptionIv = header.fields[HeaderFields.EncryptionIV]!.bytes;
     final decryptCipher = CBCBlockCipher(AESFastEngine());
     decryptCipher.init(
         false, ParametersWithIV(KeyParameter(masterKey), encryptionIv));
+    _logger.finer('decrypting ${encryptedPayload.length} with block size '
+        '${decryptCipher.blockSize}');
     final paddedDecrypted =
         AesHelper.processBlocks(decryptCipher, encryptedPayload);
 
-    final streamStart = header.fields[HeaderFields.StreamStartBytes]!.bytes!;
+    final streamStart = header.fields[HeaderFields.StreamStartBytes]!.bytes;
 
     if (paddedDecrypted.lengthInBytes < streamStart.lengthInBytes) {
       _logger.warning(
@@ -852,7 +854,7 @@ class KdbxFormat {
 
   Uint8List _decryptContentV4(
       KdbxHeader header, Uint8List cipherKey, Uint8List encryptedPayload) {
-    final encryptionIv = header.fields[HeaderFields.EncryptionIV]!.bytes!;
+    final encryptionIv = header.fields[HeaderFields.EncryptionIV]!.bytes;
 
     final decryptCipher = CBCBlockCipher(AESFastEngine());
     decryptCipher.init(
@@ -867,7 +869,7 @@ class KdbxFormat {
   /// TODO combine this with [_decryptContentV4] (or [_encryptDataAes]?)
   Uint8List _encryptContentV4Aes(
       KdbxHeader header, Uint8List cipherKey, Uint8List bytes) {
-    final encryptionIv = header.fields[HeaderFields.EncryptionIV]!.bytes!;
+    final encryptionIv = header.fields[HeaderFields.EncryptionIV]!.bytes;
     final encryptCypher = CBCBlockCipher(AESFastEngine());
     encryptCypher.init(
         true, ParametersWithIV(KeyParameter(cipherKey), encryptionIv));
@@ -879,7 +881,7 @@ class KdbxFormat {
       KdbxHeader header, Credentials credentials) async {
     final rounds = header.v3KdfTransformRounds;
     final seed = header.fields[HeaderFields.TransformSeed]!.bytes;
-    final masterSeed = header.fields[HeaderFields.MasterSeed]!.bytes!;
+    final masterSeed = header.fields[HeaderFields.MasterSeed]!.bytes;
     _logger.finer(
         'Rounds: $rounds (${ByteUtils.toHexList(header.fields[HeaderFields.TransformRounds]!.bytes)})');
     final transformedKey = await KeyEncrypterKdf.encryptAesAsync(

lib/src/kdbx_header.dart

@@ -133,7 +133,7 @@ class HeaderField implements HeaderFieldBase<HeaderFields> {
 
   @override
   final HeaderFields field;
-  final Uint8List? bytes;
+  final Uint8List bytes;
 
   String get name => field.toString();
 }
@@ -332,10 +332,10 @@ class KdbxHeader {
     if (value == null) {
       return;
     }
-    _logger.finer('Writing header $field (${value.bytes!.lengthInBytes})');
+    _logger.finer('Writing header $field (${value.bytes.lengthInBytes})');
     writer.writeUint8(field.index);
-    _writeFieldSize(writer, value.bytes!.lengthInBytes);
-    writer.writeBytes(value.bytes!);
+    _writeFieldSize(writer, value.bytes.lengthInBytes);
+    writer.writeBytes(value.bytes);
   }
 
   void _writeFieldSize(WriterHelper writer, int size) {
@@ -427,7 +427,7 @@ class KdbxHeader {
           ReaderHelper reader,
           KdbxVersion version,
           List<TE> fields,
-          T Function(TE field, Uint8List? bytes) createField) =>
+          T Function(TE field, Uint8List bytes) createField) =>
       Map<TE, T>.fromEntries(readField(reader, version, fields, createField)
           .map((field) => MapEntry(field.field, field)));
 
@@ -435,12 +435,13 @@ class KdbxHeader {
       ReaderHelper reader,
       KdbxVersion version,
       List<TE> fields,
-      T Function(TE field, Uint8List? bytes) createField) sync* {
+      T Function(TE field, Uint8List bytes) createField) sync* {
     while (true) {
       final headerId = reader.readUint8();
       final bodySize =
           version >= KdbxVersion.V4 ? reader.readUint32() : reader.readUint16();
-      final bodyBytes = bodySize > 0 ? reader.readBytes(bodySize) : null;
+      final bodyBytes =
+          bodySize > 0 ? reader.readBytes(bodySize) : Uint8List(0);
 //      _logger.finer(
 //          'Read header ${fields[headerId]}: ${ByteUtils.toHexList(bodyBytes)}');
       if (headerId > 0) {
@@ -476,22 +477,21 @@ class KdbxHeader {
   Cipher? get cipher {
     if (version < KdbxVersion.V4) {
       assert(
-          CryptoConsts.cipherFromBytes(fields[HeaderFields.CipherID]!.bytes!) ==
+          CryptoConsts.cipherFromBytes(fields[HeaderFields.CipherID]!.bytes) ==
               Cipher.aes);
       return Cipher.aes;
     }
     try {
-      return CryptoConsts.cipherFromBytes(
-          fields[HeaderFields.CipherID]!.bytes!);
+      return CryptoConsts.cipherFromBytes(fields[HeaderFields.CipherID]!.bytes);
     } catch (e, stackTrace) {
       _logger.warning(
           'Unable to find cipher. '
-          '${fields[HeaderFields.CipherID]?.bytes?.encodeBase64()}',
+          '${fields[HeaderFields.CipherID]?.bytes.encodeBase64()}',
           e,
           stackTrace);
       throw KdbxCorruptedFileException(
         'Invalid cipher. '
-        '${fields[HeaderFields.CipherID]?.bytes?.encodeBase64()}',
+        '${fields[HeaderFields.CipherID]?.bytes.encodeBase64()}',
       );
     }
   }

pubspec.yaml

@@ -1,6 +1,6 @@
 name: kdbx
 description: KeepassX format implementation in pure dart. (kdbx 3.x and 4.x support).
-version: 2.0.0
+version: 2.0.0+1
 homepage: https://github.com/authpass/kdbx.dart
 
 environment: