public function keygen(): string
    {
        try { // Catch Defuse exceptions.
            if (!($key = Key::createNewRandomKey()->saveToAsciiSafeString())) {
                throw new Exception('Defuse keygen failure.');
            }
        } catch (\Throwable $Exception) {
            throw $this->c::issue($Exception->getMessage());
        }
        return $key;
    }