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- signatures are now only verified if you're requesting the server host key since otherwise the sever could be using it's own made up host key and you'd never know
git-svn-id: http://phpseclib.svn.sourceforge.net/svnroot/phpseclib/trunk@104 21d32557-59b3-4da0-833f-c5933fad653e
This commit is contained in:
Jim Wigginton
parent
fa9e1f4f50
commit
b1566eed93
@ -60,7 +60,7 @@
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* @author Jim Wigginton <terrafrost@php.net>
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* @copyright MMVII Jim Wigginton
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* @license http://www.gnu.org/licenses/lgpl.txt
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* @version $Id: SSH2.php,v 1.42 2010-04-07 03:50:54 terrafrost Exp $
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* @version $Id: SSH2.php,v 1.43 2010-04-22 16:06:43 terrafrost Exp $
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* @link http://phpseclib.sourceforge.net
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*/
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@ -541,6 +541,28 @@ class Net_SSH2 {
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*/
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var $window_size_client_to_server = array();
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/**
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* Server signature
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*
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* Verified against $this->session_id
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*
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* @see Net_SSH2::getServerPublicHostKey()
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* @var String
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* @access private
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*/
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var $signature = '';
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/**
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* Server signature format
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*
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* ssh-rsa or ssh-dss.
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*
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* @see Net_SSH2::getServerPublicHostKey()
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* @var String
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* @access private
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*/
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var $signature_format = '';
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/**
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* Default Constructor.
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*
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@ -979,10 +1001,10 @@ class Net_SSH2 {
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$f = new Math_BigInteger($fBytes, -256);
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$temp = unpack('Nlength', $this->_string_shift($response, 4));
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$signature = $this->_string_shift($response, $temp['length']);
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$this->signature = $this->_string_shift($response, $temp['length']);
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$temp = unpack('Nlength', $this->_string_shift($signature, 4));
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$signature_format = $this->_string_shift($signature, $temp['length']);
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$temp = unpack('Nlength', $this->_string_shift($this->signature, 4));
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$this->signature_format = $this->_string_shift($this->signature, $temp['length']);
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$key = $f->modPow($x, $p);
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$keyBytes = $key->toBytes(true);
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@ -1000,124 +1022,17 @@ class Net_SSH2 {
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$this->session_id = $source;
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}
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// if you the server's assymetric key matches the one you have on file, then you should be able to decrypt the
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// "signature" and get something that should equal the "exchange hash", as defined in the SSH-2 specs.
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// here, we just check to see if the "signature" is good. you can verify whether or not the assymetric key is good,
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// later, with the getServerHostKeyAlgorithm() function
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for ($i = 0; $i < count($server_host_key_algorithms) && !in_array($server_host_key_algorithms[$i], $this->server_host_key_algorithms); $i++);
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if ($i == count($server_host_key_algorithms)) {
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user_error('No compatible server host key algorithms found', E_USER_NOTICE);
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return $this->_disconnect(NET_SSH2_DISCONNECT_KEY_EXCHANGE_FAILED);
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}
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if ($public_key_format != $server_host_key_algorithms[$i] || $signature_format != $server_host_key_algorithms[$i]) {
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if ($public_key_format != $server_host_key_algorithms[$i] || $this->signature_format != $server_host_key_algorithms[$i]) {
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user_error('Sever Host Key Algorithm Mismatch', E_USER_NOTICE);
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return $this->_disconnect(NET_SSH2_DISCONNECT_KEY_EXCHANGE_FAILED);
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}
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switch ($server_host_key_algorithms[$i]) {
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case 'ssh-dss':
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$temp = unpack('Nlength', $this->_string_shift($server_public_host_key, 4));
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$p = new Math_BigInteger($this->_string_shift($server_public_host_key, $temp['length']), -256);
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$temp = unpack('Nlength', $this->_string_shift($server_public_host_key, 4));
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$q = new Math_BigInteger($this->_string_shift($server_public_host_key, $temp['length']), -256);
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$temp = unpack('Nlength', $this->_string_shift($server_public_host_key, 4));
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$g = new Math_BigInteger($this->_string_shift($server_public_host_key, $temp['length']), -256);
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$temp = unpack('Nlength', $this->_string_shift($server_public_host_key, 4));
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$y = new Math_BigInteger($this->_string_shift($server_public_host_key, $temp['length']), -256);
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/* The value for 'dss_signature_blob' is encoded as a string containing
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r, followed by s (which are 160-bit integers, without lengths or
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padding, unsigned, and in network byte order). */
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$temp = unpack('Nlength', $this->_string_shift($signature, 4));
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if ($temp['length'] != 40) {
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user_error('Invalid signature', E_USER_NOTICE);
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return $this->_disconnect(NET_SSH2_DISCONNECT_KEY_EXCHANGE_FAILED);
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}
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$r = new Math_BigInteger($this->_string_shift($signature, 20), 256);
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$s = new Math_BigInteger($this->_string_shift($signature, 20), 256);
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if ($r->compare($q) >= 0 || $s->compare($q) >= 0) {
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user_error('Invalid signature', E_USER_NOTICE);
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return $this->_disconnect(NET_SSH2_DISCONNECT_KEY_EXCHANGE_FAILED);
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}
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$w = $s->modInverse($q);
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$u1 = $w->multiply(new Math_BigInteger(sha1($this->session_id), 16));
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list(, $u1) = $u1->divide($q);
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$u2 = $w->multiply($r);
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list(, $u2) = $u2->divide($q);
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$g = $g->modPow($u1, $p);
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$y = $y->modPow($u2, $p);
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$v = $g->multiply($y);
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list(, $v) = $v->divide($p);
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list(, $v) = $v->divide($q);
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if (!$v->equals($r)) {
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user_error('Bad server signature', E_USER_NOTICE);
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return $this->_disconnect(NET_SSH2_DISCONNECT_HOST_KEY_NOT_VERIFIABLE);
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}
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break;
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case 'ssh-rsa':
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$temp = unpack('Nlength', $this->_string_shift($server_public_host_key, 4));
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$e = new Math_BigInteger($this->_string_shift($server_public_host_key, $temp['length']), -256);
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$temp = unpack('Nlength', $this->_string_shift($server_public_host_key, 4));
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$n = new Math_BigInteger($this->_string_shift($server_public_host_key, $temp['length']), -256);
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$nLength = $temp['length'];
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/*
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$temp = unpack('Nlength', $this->_string_shift($signature, 4));
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$signature = $this->_string_shift($signature, $temp['length']);
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if (!class_exists('Crypt_RSA')) {
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require_once('Crypt/RSA.php');
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}
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$rsa = new Crypt_RSA();
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$rsa->setSignatureMode(CRYPT_RSA_SIGNATURE_PKCS1);
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$rsa->loadKey(array('e' => $e, 'n' => $n), CRYPT_RSA_PUBLIC_FORMAT_RAW);
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if (!$rsa->verify($this->session_id, $signature)) {
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user_error('Bad server signature', E_USER_NOTICE);
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return $this->_disconnect(NET_SSH2_DISCONNECT_HOST_KEY_NOT_VERIFIABLE);
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}
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*/
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$temp = unpack('Nlength', $this->_string_shift($signature, 4));
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$s = new Math_BigInteger($this->_string_shift($signature, $temp['length']), 256);
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// validate an RSA signature per "8.2 RSASSA-PKCS1-v1_5", "5.2.2 RSAVP1", and "9.1 EMSA-PSS" in the
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// following URL:
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// ftp://ftp.rsasecurity.com/pub/pkcs/pkcs-1/pkcs-1v2-1.pdf
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// also, see SSHRSA.c (rsa2_verifysig) in PuTTy's source.
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if ($s->compare(new Math_BigInteger()) < 0 || $s->compare($n->subtract(new Math_BigInteger(1))) > 0) {
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user_error('Invalid signature', E_USER_NOTICE);
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return $this->_disconnect(NET_SSH2_DISCONNECT_KEY_EXCHANGE_FAILED);
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}
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$s = $s->modPow($e, $n);
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$s = $s->toBytes();
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$h = pack('N4H*', 0x00302130, 0x0906052B, 0x0E03021A, 0x05000414, sha1($this->session_id));
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$h = chr(0x01) . str_repeat(chr(0xFF), $nLength - 3 - strlen($h)) . $h;
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if ($s != $h) {
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user_error('Bad server signature', E_USER_NOTICE);
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return $this->_disconnect(NET_SSH2_DISCONNECT_HOST_KEY_NOT_VERIFIABLE);
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}
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}
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$packet = pack('C',
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NET_SSH2_MSG_NEWKEYS
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);
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@ -2260,13 +2175,122 @@ class Net_SSH2 {
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* Returns the server public host key.
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*
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* Caching this the first time you connect to a server and checking the result on subsequent connections
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* is recommended.
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* is recommended. Returns false if the server signature is not signed correctly with the public host key.
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*
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* @return Array
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* @return Mixed
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* @access public
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*/
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function getServerPublicHostKey()
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{
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$signature = $this->signature;
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$server_public_host_key = $this->server_public_host_key;
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extract(unpack('Nlength', $this->_string_shift($server_public_host_key, 4)));
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$this->_string_shift($server_public_host_key, $length);
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switch ($this->signature_format) {
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case 'ssh-dss':
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$temp = unpack('Nlength', $this->_string_shift($server_public_host_key, 4));
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$p = new Math_BigInteger($this->_string_shift($server_public_host_key, $temp['length']), -256);
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$temp = unpack('Nlength', $this->_string_shift($server_public_host_key, 4));
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$q = new Math_BigInteger($this->_string_shift($server_public_host_key, $temp['length']), -256);
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$temp = unpack('Nlength', $this->_string_shift($server_public_host_key, 4));
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$g = new Math_BigInteger($this->_string_shift($server_public_host_key, $temp['length']), -256);
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$temp = unpack('Nlength', $this->_string_shift($server_public_host_key, 4));
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$y = new Math_BigInteger($this->_string_shift($server_public_host_key, $temp['length']), -256);
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/* The value for 'dss_signature_blob' is encoded as a string containing
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r, followed by s (which are 160-bit integers, without lengths or
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padding, unsigned, and in network byte order). */
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$temp = unpack('Nlength', $this->_string_shift($signature, 4));
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if ($temp['length'] != 40) {
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user_error('Invalid signature', E_USER_NOTICE);
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return $this->_disconnect(NET_SSH2_DISCONNECT_KEY_EXCHANGE_FAILED);
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}
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$r = new Math_BigInteger($this->_string_shift($signature, 20), 256);
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$s = new Math_BigInteger($this->_string_shift($signature, 20), 256);
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if ($r->compare($q) >= 0 || $s->compare($q) >= 0) {
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user_error('Invalid signature', E_USER_NOTICE);
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return $this->_disconnect(NET_SSH2_DISCONNECT_KEY_EXCHANGE_FAILED);
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}
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$w = $s->modInverse($q);
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$u1 = $w->multiply(new Math_BigInteger(sha1($this->session_id), 16));
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list(, $u1) = $u1->divide($q);
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$u2 = $w->multiply($r);
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list(, $u2) = $u2->divide($q);
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$g = $g->modPow($u1, $p);
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$y = $y->modPow($u2, $p);
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$v = $g->multiply($y);
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list(, $v) = $v->divide($p);
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list(, $v) = $v->divide($q);
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if (!$v->equals($r)) {
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user_error('Bad server signature', E_USER_NOTICE);
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return $this->_disconnect(NET_SSH2_DISCONNECT_HOST_KEY_NOT_VERIFIABLE);
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}
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break;
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case 'ssh-rsa':
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$temp = unpack('Nlength', $this->_string_shift($server_public_host_key, 4));
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$e = new Math_BigInteger($this->_string_shift($server_public_host_key, $temp['length']), -256);
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$temp = unpack('Nlength', $this->_string_shift($server_public_host_key, 4));
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$n = new Math_BigInteger($this->_string_shift($server_public_host_key, $temp['length']), -256);
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$nLength = $temp['length'];
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/*
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$temp = unpack('Nlength', $this->_string_shift($signature, 4));
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$signature = $this->_string_shift($signature, $temp['length']);
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if (!class_exists('Crypt_RSA')) {
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require_once('Crypt/RSA.php');
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}
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$rsa = new Crypt_RSA();
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$rsa->setSignatureMode(CRYPT_RSA_SIGNATURE_PKCS1);
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$rsa->loadKey(array('e' => $e, 'n' => $n), CRYPT_RSA_PUBLIC_FORMAT_RAW);
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if (!$rsa->verify($this->session_id, $signature)) {
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user_error('Bad server signature', E_USER_NOTICE);
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return $this->_disconnect(NET_SSH2_DISCONNECT_HOST_KEY_NOT_VERIFIABLE);
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}
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*/
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$temp = unpack('Nlength', $this->_string_shift($signature, 4));
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$s = new Math_BigInteger($this->_string_shift($signature, $temp['length']), 256);
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// validate an RSA signature per "8.2 RSASSA-PKCS1-v1_5", "5.2.2 RSAVP1", and "9.1 EMSA-PSS" in the
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// following URL:
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// ftp://ftp.rsasecurity.com/pub/pkcs/pkcs-1/pkcs-1v2-1.pdf
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// also, see SSHRSA.c (rsa2_verifysig) in PuTTy's source.
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if ($s->compare(new Math_BigInteger()) < 0 || $s->compare($n->subtract(new Math_BigInteger(1))) > 0) {
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user_error('Invalid signature', E_USER_NOTICE);
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return $this->_disconnect(NET_SSH2_DISCONNECT_KEY_EXCHANGE_FAILED);
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}
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$s = $s->modPow($e, $n);
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$s = $s->toBytes();
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$h = pack('N4H*', 0x00302130, 0x0906052B, 0x0E03021A, 0x05000414, sha1($this->session_id));
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$h = chr(0x01) . str_repeat(chr(0xFF), $nLength - 3 - strlen($h)) . $h;
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if ($s != $h) {
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user_error('Bad server signature', E_USER_NOTICE);
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return $this->_disconnect(NET_SSH2_DISCONNECT_HOST_KEY_NOT_VERIFIABLE);
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}
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}
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return $this->server_public_host_key;
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}
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}
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