Flutter Android login vault: local DB (id+base64 content), email/Google auth, dashboard search/edit/swipe-delete, dark/system theme, minSdk 29

lib/encryptor.dart

@@ -0,0 +1,29 @@
+import 'dart:convert';
+import 'package:login_vault_app/constants.dart';
+
+/// XOR cipher keyed by [AppConstants.encryptionKey], then base64-encoded.
+///
+/// Operates on raw bytes so any Unicode content round-trips correctly.
+class Encryptor {
+  static List<int> _xorBytes(List<int> input, List<int> key) {
+    final out = List<int>.filled(input.length, 0);
+    for (var i = 0; i < input.length; i++) {
+      out[i] = input[i] ^ key[i % key.length];
+    }
+    return out;
+  }
+
+  /// Encrypt [plain] -> base64 string using the constant key.
+  static String encrypt(String plain) {
+    final keyBytes = utf8.encode(AppConstants.encryptionKey);
+    final xored = _xorBytes(utf8.encode(plain), keyBytes);
+    return base64.encode(xored);
+  }
+
+  /// Decrypt a base64 [cipher] produced by [encrypt].
+  static String decrypt(String cipher) {
+    final keyBytes = utf8.encode(AppConstants.encryptionKey);
+    final xored = _xorBytes(base64.decode(cipher), keyBytes);
+    return utf8.decode(xored);
+  }
+}