diff --git a/lib/kdbx.dart b/lib/kdbx.dart
index f0c3bed..6911f20 100644
--- a/lib/kdbx.dart
+++ b/lib/kdbx.dart
@@ -9,7 +9,7 @@ export 'src/kdbx_binary.dart' show KdbxBinary;
 export 'src/kdbx_consts.dart';
 export 'src/kdbx_custom_data.dart';
 export 'src/kdbx_dao.dart' show KdbxDao;
-export 'src/kdbx_entry.dart' show KdbxEntry, KdbxKey;
+export 'src/kdbx_entry.dart' show KdbxEntry, KdbxKey, KdbxKeyCommon;
 export 'src/kdbx_file.dart';
 export 'src/kdbx_format.dart'
     show
diff --git a/lib/src/kdbx_entry.dart b/lib/src/kdbx_entry.dart
index 35d347a..4ba0d42 100644
--- a/lib/src/kdbx_entry.dart
+++ b/lib/src/kdbx_entry.dart
@@ -18,9 +18,44 @@ import 'package:xml/xml.dart';
 
 final _logger = Logger('kdbx.kdbx_entry');
 
+class KdbxKeyCommon {
+  static const KEY_TITLE = 'Title';
+  static const KEY_URL = 'URL';
+  static const KEY_USER_NAME = 'UserName';
+  static const KEY_PASSWORD = 'Password';
+  static const KEY_OTP = 'OTPAuth';
+
+  static const KdbxKey TITLE = KdbxKey._(KEY_TITLE, 'title');
+  static const KdbxKey URL = KdbxKey._(KEY_URL, 'url');
+  static const KdbxKey USER_NAME = KdbxKey._(KEY_USER_NAME, 'username');
+  static const KdbxKey PASSWORD = KdbxKey._(KEY_PASSWORD, 'password');
+  static const KdbxKey OTP = KdbxKey._(KEY_OTP, 'otpauth');
+
+  static const List<KdbxKey> all = [
+    TITLE,
+    URL,
+    USER_NAME,
+    PASSWORD,
+    OTP,
+  ];
+}
+
+// this is called during initialization of [KdbxFormat] to make sure there are
+// no typos in the constant declared above.
+bool kdbxKeyCommonAssertConsistency() {
+  assert((() {
+    for (final key in KdbxKeyCommon.all) {
+      assert(key.key.toLowerCase() == key._canonicalKey);
+    }
+    return true;
+  })());
+  return true;
+}
+
 /// Represents a case insensitive (but case preserving) key.
 class KdbxKey {
   KdbxKey(this.key) : _canonicalKey = key.toLowerCase();
+  const KdbxKey._(this.key, this._canonicalKey);
 
   final String key;
   final String _canonicalKey;
@@ -290,9 +325,9 @@ class KdbxEntry extends KdbxObject {
   }
 
   String get label =>
-      _plainValue(KdbxKey('Title')) ?? _plainValue(KdbxKey('URL'));
+      _plainValue(KdbxKeyCommon.TITLE) ?? _plainValue(KdbxKeyCommon.URL);
 
-  set label(String label) => setString(KdbxKey('Title'), PlainValue(label));
+  set label(String label) => setString(KdbxKeyCommon.TITLE, PlainValue(label));
 
   /// Creates a new binary and adds it to this entry.
   KdbxBinary createBinary({
@@ -386,7 +421,7 @@ class KdbxEntry extends KdbxObject {
     mergeContext.markAsMerged(this);
   }
 
-  String debugLabel() => label ?? _plainValue(KdbxKey('UserName'));
+  String debugLabel() => label ?? _plainValue(KdbxKeyCommon.USER_NAME);
 
   @override
   String toString() {
diff --git a/lib/src/kdbx_format.dart b/lib/src/kdbx_format.dart
index 46a55c9..e46c769 100644
--- a/lib/src/kdbx_format.dart
+++ b/lib/src/kdbx_format.dart
@@ -4,6 +4,7 @@ import 'dart:io';
 import 'dart:typed_data';
 
 import 'package:archive/archive.dart';
+import 'package:kdbx/src/kdbx_entry.dart';
 import 'package:supercharged_dart/supercharged_dart.dart';
 import 'package:argon2_ffi_base/argon2_ffi_base.dart';
 import 'package:convert/convert.dart' as convert;
@@ -470,7 +471,7 @@ class _KeysV4 {
 }
 
 class KdbxFormat {
-  KdbxFormat([this.argon2]);
+  KdbxFormat([this.argon2]) : assert(kdbxKeyCommonAssertConsistency());
 
   final Argon2 argon2;
   static bool dartWebWorkaround = false;
diff --git a/lib/src/utils/print_utils.dart b/lib/src/utils/print_utils.dart
index b93c976..8d468ba 100644
--- a/lib/src/utils/print_utils.dart
+++ b/lib/src/utils/print_utils.dart
@@ -24,7 +24,7 @@ class KdbxPrintUtils {
         forceDecrypt ? value?.getText() : value?.toString();
 
     for (final entry in group.entries) {
-      final value = entry.getString(KdbxKey('Password'));
+      final value = entry.getString(KdbxKeyCommon.PASSWORD);
       buf.writeln('$indent `- ${entry.debugLabel()}: '
           '${valueToSting(value)}');
       if (allFields) {
diff --git a/test/kdbx4_test.dart b/test/kdbx4_test.dart
index e625e5b..b853c2d 100644
--- a/test/kdbx4_test.dart
+++ b/test/kdbx4_test.dart
@@ -24,7 +24,7 @@ void main() {
       final file = await kdbxFormat.read(
           data, Credentials(ProtectedValue.fromString('asdf')));
       final firstEntry = file.body.rootGroup.entries.first;
-      final pwd = firstEntry.getString(KdbxKey('Password')).getText();
+      final pwd = firstEntry.getString(KdbxKeyCommon.PASSWORD).getText();
       expect(pwd, 'MyPassword');
     });
     test('Reading kdbx4_keeweb', () async {
@@ -32,7 +32,7 @@ void main() {
       final file = await kdbxFormat.read(
           data, Credentials(ProtectedValue.fromString('asdf')));
       final firstEntry = file.body.rootGroup.entries.first;
-      final pwd = firstEntry.getString(KdbxKey('Password')).getText();
+      final pwd = firstEntry.getString(KdbxKeyCommon.PASSWORD).getText();
       expect(pwd, 'def');
     });
     test('Reading kdbx4_keeweb modification time', () async {
@@ -135,7 +135,7 @@ KdbxEntry _createEntry(
     KdbxFile file, KdbxGroup group, String username, String password) {
   final entry = KdbxEntry.create(file, group);
   group.addEntry(entry);
-  entry.setString(KdbxKey('UserName'), PlainValue(username));
-  entry.setString(KdbxKey('Password'), ProtectedValue.fromString(password));
+  entry.setString(KdbxKeyCommon.USER_NAME, PlainValue(username));
+  entry.setString(KdbxKeyCommon.PASSWORD, ProtectedValue.fromString(password));
   return entry;
 }
diff --git a/test/kdbx_binaries_test.dart b/test/kdbx_binaries_test.dart
index 9a6fe7d..e1556a4 100644
--- a/test/kdbx_binaries_test.dart
+++ b/test/kdbx_binaries_test.dart
@@ -90,7 +90,7 @@ void main() {
           await TestUtil.readKdbxFile('test/keepass2binaries.kdbx');
       final updateEntry = (KdbxFile file) {
         final entry = fileRead.body.rootGroup.entries.first;
-        entry.setString(KdbxKey('title'), PlainValue('example'));
+        entry.setString(KdbxKeyCommon.TITLE, PlainValue('example'));
       };
       updateEntry(fileRead);
       final saved = await fileRead.save();
diff --git a/test/kdbx_test.dart b/test/kdbx_test.dart
index 05774e1..45fa15f 100644
--- a/test/kdbx_test.dart
+++ b/test/kdbx_test.dart
@@ -74,7 +74,7 @@ void main() {
       final entry = KdbxEntry.create(kdbx, rootGroup);
       rootGroup.addEntry(entry);
       entry.setString(
-          KdbxKey('Password'), ProtectedValue.fromString('LoremIpsum'));
+          KdbxKeyCommon.PASSWORD, ProtectedValue.fromString('LoremIpsum'));
       print(kdbx.body
           .generateXml(FakeProtectedSaltGenerator())
           .toXmlString(pretty: true));
@@ -86,7 +86,7 @@ void main() {
       final file = await TestUtil.readKdbxFile('test/keepass2test.kdbx');
       final first = file.body.rootGroup.entries.first;
       expect(file.header.version.major, 3);
-      expect(first.getString(KdbxKey('Title')).getText(), 'Sample Entry');
+      expect(first.getString(KdbxKeyCommon.TITLE).getText(), 'Sample Entry');
       final modTime = first.times.lastModificationTime.get();
       expect(modTime, DateTime.utc(2020, 5, 6, 7, 31, 48));
     });
@@ -96,7 +96,7 @@ void main() {
       {
         final first = file.body.rootGroup.entries.first;
         expect(file.header.version.major, 3);
-        expect(first.getString(KdbxKey('Title')).getText(), 'Sample Entry');
+        expect(first.getString(KdbxKeyCommon.TITLE).getText(), 'Sample Entry');
         first.times.lastModificationTime.set(newModDate);
       }
       final saved = await file.save();
@@ -118,7 +118,7 @@ void main() {
         final entry = KdbxEntry.create(kdbx, rootGroup);
         rootGroup.addEntry(entry);
         entry.setString(
-            KdbxKey('Password'), ProtectedValue.fromString('LoremIpsum'));
+            KdbxKeyCommon.PASSWORD, ProtectedValue.fromString('LoremIpsum'));
         return kdbx.save();
       })();
 
@@ -127,7 +127,7 @@ void main() {
       final kdbx = await kdbxForamt.read(saved, credentials);
       expect(
           kdbx.body.rootGroup.entries.first
-              .getString(KdbxKey('Password'))
+              .getString(KdbxKeyCommon.PASSWORD)
               .getText(),
           'LoremIpsum');
       File('test.kdbx').writeAsBytesSync(saved);
diff --git a/test/merge/kdbx_merge_test.dart b/test/merge/kdbx_merge_test.dart
index 395522a..9a323b8 100644
--- a/test/merge/kdbx_merge_test.dart
+++ b/test/merge/kdbx_merge_test.dart
@@ -46,7 +46,7 @@ void main() {
         final fileMod = await TestUtil.saveAndRead(file);
 
         fileMod.body.rootGroup.entries.first
-            .setString(KdbxKey('UserName'), PlainValue('changed.'));
+            .setString(KdbxKeyCommon.USER_NAME, PlainValue('changed.'));
         _logger.info('mod date: ' +
             fileMod.body.rootGroup.entries.first.times.lastModificationTime
                 .get()
@@ -103,7 +103,7 @@ KdbxEntry _createEntry(
     KdbxFile file, KdbxGroup group, String username, String password) {
   final entry = KdbxEntry.create(file, group);
   group.addEntry(entry);
-  entry.setString(KdbxKey('UserName'), PlainValue(username));
-  entry.setString(KdbxKey('Password'), ProtectedValue.fromString(password));
+  entry.setString(KdbxKeyCommon.USER_NAME, PlainValue(username));
+  entry.setString(KdbxKeyCommon.PASSWORD, ProtectedValue.fromString(password));
   return entry;
 }