php - phpseclib で extKeyUsage を設定するにはどうすればよいですか?

Question

phpseclib で署名している証明書に SSL サーバーと SSL クライアントのフラグを追加したいのですが、どうすればよいですか? setExtension 関数を見つけましたが、使い方がわかりません。どんな助けでも大歓迎です、ありがとう。

私は次のことを試しましたが、うまくいきません(主にphpseclibの例から):

// create private key for CA cert
$CAPrivKey = new Crypt_RSA();
extract($CAPrivKey->createKey());
$CAPrivKey->loadKey($privatekey);

$pubKey = new Crypt_RSA();
$pubKey->loadKey($publickey);
$pubKey->setPublicKey();

echo "the private key for the CA cert (can be discarded):\r\n\r\n";
echo $privatekey;
echo "\r\n\r\n";


// create a self-signed cert that'll serve as the CA
$subject = new File_X509();
$subject->setPublicKey($pubKey);
$subject->setDNProp('id-at-organizationName', 'phpseclib demo CA');

$issuer = new File_X509();
$issuer->setPrivateKey($CAPrivKey);
$issuer->setDN($CASubject = $subject->getDN());

$x509 = new File_X509();
$x509->setStartDate('-1 month');
$x509->setEndDate('+1 year');
$x509->setSerialNumber(chr(1));
$x509->makeCA();

$result = $x509->sign($issuer, $subject);
echo "the CA cert to be imported into the browser is as follows:\r\n\r\n";
echo $x509->saveX509($result);
echo "\r\n\r\n";


// create private key / x.509 cert for stunnel / website
$privKey = new Crypt_RSA();
extract($privKey->createKey());
$privKey->loadKey($privatekey);

$pubKey = new Crypt_RSA();
$pubKey->loadKey($publickey);
$pubKey->setPublicKey();

$subject = new File_X509();
$subject->setPublicKey($pubKey);
$subject->setDNProp('id-at-organizationName', 'phpseclib demo cert');
$subject->setDomain('www.google.com');

$issuer = new File_X509();
$issuer->setPrivateKey($CAPrivKey);
$issuer->setDN($CASubject);

$x509 = new File_X509();
$x509->setStartDate('-1 month');
$x509->setEndDate('+1 year');
$x509->setSerialNumber(chr(1));
$x509->setExtension('id-ce-extKeyUsage', array('id-kp-serverAuth', 'id-kp-clientAuth'));

$result = $x509->sign($issuer, $subject);

echo "the stunnel.pem contents are as follows:\r\n\r\n";
echo $privKey->getPrivateKey();
echo "\r\n";
echo $x509->saveX509($result);
echo "\r\n";