import 'dart:math'; const _chars = 'AaBbCcDdEeFfGgHhIiJjKkLlMmNnOoPpQqRrSsTtUuVvWwXxYyZz1234567890'; Random _rnd = Random(); String getClientSecret(int length) => String.fromCharCodes(Iterable.generate( length, (_) => _chars.codeUnitAt(_rnd.nextInt(_chars.length))));