/**
* Construct a new SSH_MSG_KEXDH_REPLY message.
*
* \param fpoirotte::Pssht::Messages::KEXDH::INIT $kexDHInit
* Client's contribution to the Diffie-Hellman Key Exchange.
*
* \param fpoirotte::Pssht::PublicKeyInterface $key
* Server's public key.
*
* \param fpoirotte::Pssht::EncryptionInterface $encryptionAlgo
* Encryption algorithm in use.
*
* \param fpoirotte::Pssht::KEXInterface $kexAlgo
* Key exchange algorithm to use.
*
* \param fpoirotte::Pssht::Messages::KEXINIT $serverKEX
* Algorithms supported by the server.
*
* \param fpoirotte::Pssht::Messages::KEXINIT $clientKEX
* Algorithms supported by the client.
*
* \param string $serverIdent
* Server's identification string
*
* \param string $clientIdent
* Client's identification string
*/
public function __construct(\fpoirotte\Pssht\Messages\KEXDH\INIT $kexDHInit, \fpoirotte\Pssht\PublicKeyInterface $key, \fpoirotte\Pssht\EncryptionInterface $encryptionAlgo, \fpoirotte\Pssht\KEXInterface $kexAlgo, \fpoirotte\Pssht\Messages\KEXINIT $serverKEX, \fpoirotte\Pssht\Messages\KEXINIT $clientKEX, $serverIdent, $clientIdent)
{
if (!is_string($serverIdent)) {
throw new \InvalidArgumentException();
}
if (!is_string($clientIdent)) {
throw new \InvalidArgumentException();
}
$keyLength = min(20, max($encryptionAlgo->getKeySize(), 16));
$randBytes = openssl_random_pseudo_bytes(2 * $keyLength);
$y = gmp_init(bin2hex($randBytes), 16);
$prime = gmp_init($kexAlgo::getPrime(), 16);
$this->f = gmp_powm($kexAlgo::getGenerator(), $y, $prime);
$this->K = gmp_powm($kexDHInit->getE(), $y, $prime);
$this->K_S = $key;
$this->kexDHInit = $kexDHInit;
$this->kexAlgo = $kexAlgo;
$this->serverKEX = $serverKEX;
$this->clientKEX = $clientKEX;
$this->serverIdent = $serverIdent;
$this->clientIdent = $clientIdent;
$msgId = chr(\fpoirotte\Pssht\Messages\KEXINIT::getMessageId());
// $sub is used to create the structure for the hashing function.
$sub = new \fpoirotte\Pssht\Wire\Encoder(new \fpoirotte\Pssht\Buffer());
$this->K_S->serialize($sub);
$K_S = $sub->getBuffer()->get(0);
$sub->encodeString($this->clientIdent);
$sub->encodeString($this->serverIdent);
// $sub2 is used to compute the value
// of various fields inside the structure.
$sub2 = new \fpoirotte\Pssht\Wire\Encoder(new \fpoirotte\Pssht\Buffer());
$sub2->encodeBytes($msgId);
// Add message identifier.
$this->clientKEX->serialize($sub2);
$sub->encodeString($sub2->getBuffer()->get(0));
$sub2->encodeBytes($msgId);
// Add message identifier.
$this->serverKEX->serialize($sub2);
$sub->encodeString($sub2->getBuffer()->get(0));
$sub->encodeString($K_S);
$sub->encodeMpint($this->kexDHInit->getE());
$sub->encodeMpint($this->f);
$sub->encodeMpint($this->K);
$logging = \Plop\Plop::getInstance();
$origData = $sub->getBuffer()->get(0);
$data = wordwrap(bin2hex($origData), 4, ' ', true);
$data = wordwrap($data, 32 + 7, PHP_EOL, true);
$logging->debug("Signature payload:\r\n%s", array($data));
$this->H = $this->kexAlgo->hash($origData);
}
protected function createResponse(\fpoirotte\Pssht\Wire\Decoder $decoder, \fpoirotte\Pssht\Transport $transport, array &$context, $hostAlgo)
{
$kexAlgo = $context['kexAlgo'];
$kexAlgo = new $kexAlgo();
$message = \fpoirotte\Pssht\Messages\KEXDH\INIT::unserialize($decoder);
/*
// @TODO: we ought to check whether the given public key is valid.
//
// Unfortunately, the current API is broken as getQ() only exists
// for ECDH. Also, even though the regular DH has a getE() method,
// it returns raw GMP resources/objects which are unusable here.
if (!$message->getQ()->isValid()) {
throw new \InvalidArgumentException();
}
*/
return new \fpoirotte\Pssht\Messages\KEXDH\REPLY($message, $context['serverKeys'][$hostAlgo], $transport->getEncryptor(), $kexAlgo, $context['kex']['server'], $context['kex']['client'], $context['identity']['server'], $context['identity']['client']);
}
public static function addHandlers(\fpoirotte\Pssht\Transport $transport)
{
$transport->setHandler(\fpoirotte\Pssht\Messages\KEXDH\INIT::getMessageId(), new \fpoirotte\Pssht\Handlers\KEXDH\INIT());
}
