generatePassword static method

String generatePassword({ required double length, })

Generate a random password with the given length length must be in range of 20 to 128

Implementation

static String generatePassword({required double length}) {
  // length must be in range of 20 to 128
  if (length < 20 || length > 128) {
    throw Exception("Password length must be in range of 20 to 128");
  }

  final Random _random = Random.secure();
  const String _validChars =
      'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789!@#\$%^&*()-_=+[]{};:,.<>?';

  String password = '';
  bool hasUpperCase = false;
  bool hasLowerCase = false;
  bool hasDigit = false;
  bool hasSymbol = false;

  while (password.length < length ||
      !hasUpperCase ||
      !hasLowerCase ||
      !hasDigit ||
      !hasSymbol) {
    password = '';
    hasUpperCase = false;
    hasLowerCase = false;
    hasDigit = false;
    hasSymbol = false;

    for (int i = 0; i < length; i++) {
      int randomIndex = _random.nextInt(_validChars.length);
      password += _validChars[randomIndex];

      if (RegExp(r'[A-Z]').hasMatch(password[i])) {
        hasUpperCase = true;
      } else if (RegExp(r'[a-z]').hasMatch(password[i])) {
        hasLowerCase = true;
      } else if (RegExp(r'[0-9]').hasMatch(password[i])) {
        hasDigit = true;
      } else {
        hasSymbol = true;
      }
    }
  }

  return password;
}