Performed first authentication

moneymgr_mobile/lib/utils/string_utils.dart

@@ -0,0 +1,12 @@
+import 'dart:math';
+
+const _chars = 'AaBbCcDdEeFfGgHhIiJjKkLlMmNnOoPpQqRrSsTtUuVvWwXxYyZz1234567890';
+final _rnd = Random();
+
+/// Generate random string
+String getRandomString(int length) => String.fromCharCodes(
+  Iterable.generate(
+    length,
+    (_) => _chars.codeUnitAt(_rnd.nextInt(_chars.length)),
+  ),
+);