function getPrivateKey($type = self::PUBLIC_FORMAT_PKCS1)
    {
        if (empty($this->primes)) {
            return false;
        }

        $oldFormat = $this->privateKeyFormat;
        $this->privateKeyFormat = $type;
        $temp = $this->_convertPrivateKey($this->modulus, $this->publicExponent, $this->exponent, $this->primes, $this->exponents, $this->coefficients);
        $this->privateKeyFormat = $oldFormat;
        return $temp;
    }