use the original ChaCha7539 from pointycastle.

lib/src/crypto/protected_salt_generator.dart

@@ -51,11 +51,11 @@ class ChachaPointyCastleProtectedSaltGenerator extends ProtectedSaltGenerator {
     final secretKey = hash.bytes.sublist(0, 32);
     final nonce = hash.bytes.sublist(32, 32 + 12);
 
-    final chacha20 = ChaCha20Engine();
+    final chacha20 = ChaCha7539Engine()
-    chacha20.init(
+      ..init(
-        null,
+          null,
-        ParametersWithIV(
+          ParametersWithIV(
-            KeyParameter(secretKey as Uint8List), nonce as Uint8List));
+              KeyParameter(secretKey as Uint8List), nonce as Uint8List));
 
     return ChachaPointyCastleProtectedSaltGenerator._(chacha20);
   }

lib/src/kdbx_format.dart

@@ -23,6 +23,7 @@ import 'package:kdbx/src/kdbx_xml.dart';
 import 'package:logging/logging.dart';
 import 'package:meta/meta.dart';
 import 'package:pointycastle/export.dart';
+import 'package:pointycastle/stream/chacha7539.dart';
 import 'package:xml/xml.dart' as xml;
 
 final _logger = Logger('kdbx.format');
@@ -542,7 +543,7 @@ class KdbxFormat {
   Uint8List transformContentV4ChaCha20(
       KdbxHeader header, Uint8List encrypted, Uint8List cipherKey) {
     final encryptionIv = header.fields[HeaderFields.EncryptionIV].bytes;
-    final engine = ChaCha20Engine()
+    final engine = ChaCha7539Engine()
       ..init(false, ParametersWithIV(KeyParameter(cipherKey), encryptionIv));
     return engine.process(encrypted);
   }

pubspec.yaml

@@ -35,13 +35,13 @@ dev_dependencies:
   test: '>=1.6.0 <2.0.0'
 
 dependency_overrides:
-#  pointycastle:
-#    git:
-#      url: https://github.com/bcgit/pc-dart.git
-#      ref: 7c8a8b47faa75432fe3fb9a739db4a289e12b341
   pointycastle:
     git:
-      url: https://github.com/authpass/pc-dart.git
+      url: https://github.com/bcgit/pc-dart.git
-      ref: 38fa40e966153b3d3cf93a9bd95228f76af3b9d7
+      ref: 7c8a8b47faa75432fe3fb9a739db4a289e12b341
+#  pointycastle:
+#    git:
+#      url: https://github.com/authpass/pc-dart.git
+#      ref: 38fa40e966153b3d3cf93a9bd95228f76af3b9d7
 #  pointycastle:
 #    path: /Users/herbert/dev/pointycastle