public static function createSalt()
    {
        $alphabet = self::ALPHABET;
        $length = strlen($alphabet);
        $salt = [];
        for ($i = 0; $i < self::SALT_LENGTH; $i++) {
            $index = mt_rand(0, $length - 1);
            $salt[] = substr($alphabet, $index, 1);
        }
        return implode('', $salt);
    }