/lib/Phpseclib/Net/SSH2.php

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<?php
/* vim: set expandtab tabstop=4 shiftwidth=4 softtabstop=4: */

/**
 * Pure-PHP implementation of SSHv2.
 *
 * PHP versions 4 and 5
 *
 * Here are some examples of how to use this library:
 * <code>
 * <?php
 *    include('Net/SSH2.php');
 *
 *    $ssh = new SSH2('www.domain.tld');
 *    if (!$ssh->login('username', 'password')) {
 *        exit('Login Failed');
 *    }
 *
 *    echo $ssh->exec('pwd');
 *    echo $ssh->exec('ls -la');
 * ?>
 * </code>
 *
 * <code>
 * <?php
 *    include('Crypt/RSA.php');
 *    include('Net/SSH2.php');
 *
 *    $key = new Crypt_RSA();
 *    //$key->setPassword('whatever');
 *    $key->loadKey(file_get_contents('privatekey'));
 *
 *    $ssh = new SSH2('www.domain.tld');
 *    if (!$ssh->login('username', $key)) {
 *        exit('Login Failed');
 *    }
 *
 *    echo $ssh->exec('pwd');
 *    echo $ssh->exec('ls -la');
 * ?>
 * </code>
 *
 * LICENSE: This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
 * MA  02111-1307  USA
 *
 * @category   Net
 * @package    SSH2
 * @author     Jim Wigginton <terrafrost@php.net>
 * @copyright  MMVII Jim Wigginton
 * @license    http://www.gnu.org/licenses/lgpl.txt
 * @version    $Id: SSH2.php 81 2010-05-19 21:56:16Z admin $
 * @link       http://phpseclib.sourceforge.net
 */

namespace Phpseclib\Net;

/**
 * Include Math_BigInteger
 *
 * Used to do Diffie-Hellman key exchange and DSA/RSA signature verification.
 */
use Phpseclib\Math\BigInteger;

/**
 * Include Crypt_Random
 */
use Phpseclib\Crypt\Random;

/**
 * Include Crypt_Hash
 */
use Phpseclib\Crypt\Hash;

/**
 * Include Crypt_TripleDES
 */
use Phpseclib\Crypt\TripleDES;

/**
 * Include Crypt_RC4
 */
use Phpseclib\Crypt\RC4;

/**
 * Include Crypt_AES
 */
use Phpseclib\Crypt\AES;

/**#@+
 * Execution Bitmap Masks
 *
 * @see SSH2::bitmap
 * @access private
 */
//define('NET_SSH2_MASK_CONSTRUCTOR', 0x00000001);
//define('NET_SSH2_MASK_LOGIN',       0x00000002);
/**#@-*/

/**#@+
 * @access public
 * @see SSH2::getLog()
 */
/**
 * Returns the message numbers
 */
//define('NET_SSH2_LOG_SIMPLE',  1);
/**
 * Returns the message content
 */
//define('NET_SSH2_LOG_COMPLEX', 2);
/**#@-*/

/**
 * Pure-PHP implementation of SSHv2.
 *
 * @author  Jim Wigginton <terrafrost@php.net>
 * @version 0.1.0
 * @access  public
 * @package SSH2
 */
class SSH2 {

    /**
     * The SSH identifier
     *
     * @var String
     * @access private
     */
    var $identifier = 'SSH-2.0-phpseclib_0.1';

    /**
     * The Socket Object
     *
     * @var Object
     * @access private
     */
    var $fsock;

    /**
     * Execution Bitmap
     *
     * The bits that are set reprsent functions that have been called already.  This is used to determine
     * if a requisite function has been successfully executed.  If not, an error should be thrown.
     *
     * @var Integer
     * @access private
     */
    var $bitmap = 0;

    /**
     * Debug Info
     *
     * @see SSH2::getDebugInfo()
     * @var String
     * @access private
     */
    var $debug_info = '';

    /**
     * Server Identifier
     *
     * @see SSH2::getServerIdentification()
     * @var String
     * @access private
     */
    var $server_identifier = '';

    /**
     * Key Exchange Algorithms
     *
     * @see SSH2::getKexAlgorithims()
     * @var Array
     * @access private
     */
    var $kex_algorithms;

    /**
     * Server Host Key Algorithms
     *
     * @see SSH2::getServerHostKeyAlgorithms()
     * @var Array
     * @access private
     */
    var $server_host_key_algorithms;

    /**
     * Encryption Algorithms: Client to Server
     *
     * @see SSH2::getEncryptionAlgorithmsClient2Server()
     * @var Array
     * @access private
     */
    var $encryption_algorithms_client_to_server;

    /**
     * Encryption Algorithms: Server to Client
     *
     * @see SSH2::getEncryptionAlgorithmsServer2Client()
     * @var Array
     * @access private
     */
    var $encryption_algorithms_server_to_client;

    /**
     * MAC Algorithms: Client to Server
     *
     * @see SSH2::getMACAlgorithmsClient2Server()
     * @var Array
     * @access private
     */
    var $mac_algorithms_client_to_server;

    /**
     * MAC Algorithms: Server to Client
     *
     * @see SSH2::getMACAlgorithmsServer2Client()
     * @var Array
     * @access private
     */
    var $mac_algorithms_server_to_client;

    /**
     * Compression Algorithms: Client to Server
     *
     * @see SSH2::getCompressionAlgorithmsClient2Server()
     * @var Array
     * @access private
     */
    var $compression_algorithms_client_to_server;

    /**
     * Compression Algorithms: Server to Client
     *
     * @see SSH2::getCompressionAlgorithmsServer2Client()
     * @var Array
     * @access private
     */
    var $compression_algorithms_server_to_client;

    /**
     * Languages: Server to Client
     *
     * @see SSH2::getLanguagesServer2Client()
     * @var Array
     * @access private
     */
    var $languages_server_to_client;

    /**
     * Languages: Client to Server
     *
     * @see SSH2::getLanguagesClient2Server()
     * @var Array
     * @access private
     */
    var $languages_client_to_server;

    /**
     * Block Size for Server to Client Encryption
     *
     * "Note that the length of the concatenation of 'packet_length',
     *  'padding_length', 'payload', and 'random padding' MUST be a multiple
     *  of the cipher block size or 8, whichever is larger.  This constraint
     *  MUST be enforced, even when using stream ciphers."
     *
     *  -- http://tools.ietf.org/html/rfc4253#section-6
     *
     * @see SSH2::SSH2()
     * @see SSH2::_send_binary_packet()
     * @var Integer
     * @access private
     */
    var $encrypt_block_size = 8;

    /**
     * Block Size for Client to Server Encryption
     *
     * @see SSH2::SSH2()
     * @see SSH2::_get_binary_packet()
     * @var Integer
     * @access private
     */
    var $decrypt_block_size = 8;

    /**
     * Server to Client Encryption Object
     *
     * @see SSH2::_get_binary_packet()
     * @var Object
     * @access private
     */
    var $decrypt = false;

    /**
     * Client to Server Encryption Object
     *
     * @see SSH2::_send_binary_packet()
     * @var Object
     * @access private
     */
    var $encrypt = false;

    /**
     * Client to Server HMAC Object
     *
     * @see SSH2::_send_binary_packet()
     * @var Object
     * @access private
     */
    var $hmac_create = false;

    /**
     * Server to Client HMAC Object
     *
     * @see SSH2::_get_binary_packet()
     * @var Object
     * @access private
     */
    var $hmac_check = false;

    /**
     * Size of server to client HMAC
     *
     * We need to know how big the HMAC will be for the server to client direction so that we know how many bytes to read.
     * For the client to server side, the HMAC object will make the HMAC as long as it needs to be.  All we need to do is
     * append it.
     *
     * @see SSH2::_get_binary_packet()
     * @var Integer
     * @access private
     */
    var $hmac_size = false;

    /**
     * Server Public Host Key
     *
     * @see SSH2::getServerPublicHostKey()
     * @var String
     * @access private
     */
    var $server_public_host_key;

    /**
     * Session identifer
     *
     * "The exchange hash H from the first key exchange is additionally
     *  used as the session identifier, which is a unique identifier for
     *  this connection."
     *
     *  -- http://tools.ietf.org/html/rfc4253#section-7.2
     *
     * @see SSH2::_key_exchange()
     * @var String
     * @access private
     */
    var $session_id = false;

    /**
     * Message Numbers
     *
     * @see SSH2::SSH2()
     * @var Array
     * @access private
     */
    var $message_numbers = array();

    /**
     * Disconnection Message 'reason codes' defined in RFC4253
     *
     * @see SSH2::SSH2()
     * @var Array
     * @access private
     */
    var $disconnect_reasons = array();

    /**
     * SSH_MSG_CHANNEL_OPEN_FAILURE 'reason codes', defined in RFC4254
     *
     * @see SSH2::SSH2()
     * @var Array
     * @access private
     */
    var $channel_open_failure_reasons = array();

    /**
     * Terminal Modes
     *
     * @link http://tools.ietf.org/html/rfc4254#section-8
     * @see SSH2::SSH2()
     * @var Array
     * @access private
     */
    var $terminal_modes = array();

    /**
     * SSH_MSG_CHANNEL_EXTENDED_DATA's data_type_codes
     *
     * @link http://tools.ietf.org/html/rfc4254#section-5.2
     * @see SSH2::SSH2()
     * @var Array
     * @access private
     */
    var $channel_extended_data_type_codes = array();

    /**
     * Send Sequence Number
     *
     * See 'Section 6.4.  Data Integrity' of rfc4253 for more info.
     *
     * @see SSH2::_send_binary_packet()
     * @var Integer
     * @access private
     */
    var $send_seq_no = 0;

    /**
     * Get Sequence Number
     *
     * See 'Section 6.4.  Data Integrity' of rfc4253 for more info.
     *
     * @see SSH2::_get_binary_packet()
     * @var Integer
     * @access private
     */
    var $get_seq_no = 0;

    /**
     * The Client Channel
     *
     * SSH2::exec() uses 0, although since SSH2::exec() doesn't send NET_SSH2_CHANNEL_DATA packets,
     * SSH2::_send_channel_packet() isn't actually called by any function in Net/SSH2.php.  Classes that
     * extend SSH2, however, might call that function, hence it's existence.
     *
     * @var Integer
     * @see SSH2::_send_channel_packet
     * @access private
     */
    var $client_channel = 1;

    /**
     * Server Channels
     *
     * Maps client channels to server channels
     *
     * @see SSH2::_get_channel_packet()
     * @see SSH2::exec()
     * @var Array
     * @access private
     */
    var $server_channels = array();

    /**
     * Packet Size
     *
     * Maximum packet size
     *
     * @see SSH2::_send_channel_packet()
     * @see SSH2::exec()
     * @var Integer
     * @access private
     */
    var $packet_size_client_to_server = 0;

    /**
     * Message Number Log
     *
     * @see SSH2::getLog()
     * @var Array
     * @access private
     */
    var $message_number_log = array();

    /**
     * Message Log
     *
     * @see SSH2::getLog()
     * @var Array
     * @access private
     */
    var $message_log = array();

    /**
     * Default Constructor.
     *
     * Connects to an SSHv2 server
     *
     * @param String $host
     * @param optional Integer $port
     * @param optional Integer $timeout
     * @return SSH2
     * @access public
     */
    function __construct($host, $port = 22, $timeout = 10)
    {
        define('NET_SSH2_MASK_CONSTRUCTOR', 0x00000001);
        define('NET_SSH2_MASK_LOGIN',       0x00000002);
        define('NET_SSH2_LOG_SIMPLE',  1);
        define('NET_SSH2_LOG_COMPLEX', 2);


        $this->message_numbers = array(
            1 => 'NET_SSH2_MSG_DISCONNECT',
            2 => 'NET_SSH2_MSG_IGNORE',
            3 => 'NET_SSH2_MSG_UNIMPLEMENTED',
            4 => 'NET_SSH2_MSG_DEBUG',
            5 => 'NET_SSH2_MSG_SERVICE_REQUEST',
            6 => 'NET_SSH2_MSG_SERVICE_ACCEPT',
            20 => 'NET_SSH2_MSG_KEXINIT',
            21 => 'NET_SSH2_MSG_NEWKEYS',
            30 => 'NET_SSH2_MSG_KEXDH_INIT',
            31 => 'NET_SSH2_MSG_KEXDH_REPLY',
            50 => 'NET_SSH2_MSG_USERAUTH_REQUEST',
            51 => 'NET_SSH2_MSG_USERAUTH_FAILURE',
            52 => 'NET_SSH2_MSG_USERAUTH_SUCCESS',
            53 => 'NET_SSH2_MSG_USERAUTH_BANNER',

            80 => 'NET_SSH2_MSG_GLOBAL_REQUEST',
            81 => 'NET_SSH2_MSG_REQUEST_SUCCESS',
            82 => 'NET_SSH2_MSG_REQUEST_FAILURE',
            90 => 'NET_SSH2_MSG_CHANNEL_OPEN',
            91 => 'NET_SSH2_MSG_CHANNEL_OPEN_CONFIRMATION',
            92 => 'NET_SSH2_MSG_CHANNEL_OPEN_FAILURE',
            93 => 'NET_SSH2_MSG_CHANNEL_WINDOW_ADJUST',
            94 => 'NET_SSH2_MSG_CHANNEL_DATA',
            95 => 'NET_SSH2_MSG_CHANNEL_EXTENDED_DATA',
            96 => 'NET_SSH2_MSG_CHANNEL_EOF',
            97 => 'NET_SSH2_MSG_CHANNEL_CLOSE',
            98 => 'NET_SSH2_MSG_CHANNEL_REQUEST',
            99 => 'NET_SSH2_MSG_CHANNEL_SUCCESS',
            100 => 'NET_SSH2_MSG_CHANNEL_FAILURE'
        );
        $this->disconnect_reasons = array(
            1 => 'NET_SSH2_DISCONNECT_HOST_NOT_ALLOWED_TO_CONNECT',
            2 => 'NET_SSH2_DISCONNECT_PROTOCOL_ERROR',
            3 => 'NET_SSH2_DISCONNECT_KEY_EXCHANGE_FAILED',
            4 => 'NET_SSH2_DISCONNECT_RESERVED',
            5 => 'NET_SSH2_DISCONNECT_MAC_ERROR',
            6 => 'NET_SSH2_DISCONNECT_COMPRESSION_ERROR',
            7 => 'NET_SSH2_DISCONNECT_SERVICE_NOT_AVAILABLE',
            8 => 'NET_SSH2_DISCONNECT_PROTOCOL_VERSION_NOT_SUPPORTED',
            9 => 'NET_SSH2_DISCONNECT_HOST_KEY_NOT_VERIFIABLE',
            10 => 'NET_SSH2_DISCONNECT_CONNECTION_LOST',
            11 => 'NET_SSH2_DISCONNECT_BY_APPLICATION',
            12 => 'NET_SSH2_DISCONNECT_TOO_MANY_CONNECTIONS',
            13 => 'NET_SSH2_DISCONNECT_AUTH_CANCELLED_BY_USER',
            14 => 'NET_SSH2_DISCONNECT_NO_MORE_AUTH_METHODS_AVAILABLE',
            15 => 'NET_SSH2_DISCONNECT_ILLEGAL_USER_NAME'
        );
        $this->channel_open_failure_reasons = array(
            1 => 'NET_SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED'
        );
        $this->terminal_modes = array(
            0 => 'NET_SSH2_TTY_OP_END'
        );
        $this->channel_extended_data_type_codes = array(
            1 => 'NET_SSH2_EXTENDED_DATA_STDERR'
        );

        $this->_define_array(
            $this->message_numbers,
            $this->disconnect_reasons,
            $this->channel_open_failure_reasons,
            $this->terminal_modes,
            $this->channel_extended_data_type_codes,
            array(60 => 'NET_SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ'),
            array(60 => 'NET_SSH2_MSG_USERAUTH_PK_OK')
        );

//var_dump('before fsockopen');

        $this->fsock = fsockopen($host, $port, $errno, $errstr, $timeout);
//var_dump($this->fsock, $host, $port, $errno, $errstr, $timeout); 
        if (!$this->fsock) {
            user_error(rtrim("Cannot connect to $host. Error $errno. $errstr"), E_USER_NOTICE);
            return;
        }


        /* According to the SSH2 specs,

          "The server MAY send other lines of data before sending the version
           string.  Each line SHOULD be terminated by a Carriage Return and Line
           Feed.  Such lines MUST NOT begin with "SSH-", and SHOULD be encoded
           in ISO-10646 UTF-8 [RFC3629] (language is not specified).  Clients
           MUST be able to process such lines." */
        $temp = '';
        while (!feof($this->fsock) && !preg_match('#^SSH-(\d\.\d+)#', $temp, $matches)) {
            if (substr($temp, -2) == "\r\n") {
                $this->debug_info.= $temp;
                $temp = '';
            }
            $temp.= fgets($this->fsock, 255);
        }

        if (defined('NET_SSH2_LOGGING')) {
            $this->message_number_log[] = '<-';
            $this->message_log[] = $temp;
            $this->message_number_log[] = '->';
            $this->message_log[] = $this->identifier . "\r\n";
        }

        $this->server_identifier = trim($temp);
        $this->debug_info = utf8_decode($this->debug_info);

        if ($matches[1] != '1.99' && $matches[1] != '2.0') {
            user_error("Cannot connect to SSH $matches[1] servers", E_USER_NOTICE);
            return;
        }

        fputs($this->fsock, $this->identifier . "\r\n");

        $response = $this->_get_binary_packet();
        if ($response === false) {
            user_error('Connection closed by server', E_USER_NOTICE);
            return;
        }

        if (ord($response[0]) != NET_SSH2_MSG_KEXINIT) {
            user_error('Expected SSH_MSG_KEXINIT', E_USER_NOTICE);
            return;
        }

        if (!$this->_key_exchange($response)) {
            return;
        }

        $this->bitmap = NET_SSH2_MASK_CONSTRUCTOR;
    }

    /**
     * Key Exchange
     *
     * @param String $kexinit_payload_server
     * @access private
     */
    function _key_exchange($kexinit_payload_server)
    {
        static $kex_algorithms = array(
            'diffie-hellman-group1-sha1', // REQUIRED
            'diffie-hellman-group14-sha1' // REQUIRED
        );

        static $server_host_key_algorithms = array(
            'ssh-rsa', // RECOMMENDED  sign   Raw RSA Key
            'ssh-dss'  // REQUIRED     sign   Raw DSS Key
        );

        static $encryption_algorithms = array(
            'arcfour',    // OPTIONAL          the ARCFOUR stream cipher with a 128-bit key
            'aes128-cbc', // RECOMMENDED       AES with a 128-bit key
            'aes192-cbc', // OPTIONAL          AES with a 192-bit key
            'aes256-cbc', // OPTIONAL          AES in CBC mode, with a 256-bit key
            '3des-cbc',   // REQUIRED          three-key 3DES in CBC mode
            'none'        // OPTIONAL          no encryption; NOT RECOMMENDED
        );

        static $mac_algorithms = array(
            'hmac-sha1-96', // RECOMMENDED     first 96 bits of HMAC-SHA1 (digest length = 12, key length = 20)
            'hmac-sha1',    // REQUIRED        HMAC-SHA1 (digest length = key length = 20)
            'hmac-md5-96',  // OPTIONAL        first 96 bits of HMAC-MD5 (digest length = 12, key length = 16)
            'hmac-md5',     // OPTIONAL        HMAC-MD5 (digest length = key length = 16)
            'none'          // OPTIONAL        no MAC; NOT RECOMMENDED
        );

        static $compression_algorithms = array(
            'none'   // REQUIRED        no compression
            //'zlib' // OPTIONAL        ZLIB (LZ77) compression
        );

        static $str_kex_algorithms, $str_server_host_key_algorithms,
               $encryption_algorithms_server_to_client, $mac_algorithms_server_to_client, $compression_algorithms_server_to_client,
               $encryption_algorithms_client_to_server, $mac_algorithms_client_to_server, $compression_algorithms_client_to_server;

        if (empty($str_kex_algorithms)) {
            $str_kex_algorithms = implode(',', $kex_algorithms);
            $str_server_host_key_algorithms = implode(',', $server_host_key_algorithms);
            $encryption_algorithms_server_to_client = $encryption_algorithms_client_to_server = implode(',', $encryption_algorithms);
            $mac_algorithms_server_to_client = $mac_algorithms_client_to_server = implode(',', $mac_algorithms);
            $compression_algorithms_server_to_client = $compression_algorithms_client_to_server = implode(',', $compression_algorithms);
        }

        $client_cookie = '';
        for ($i = 0; $i < 16; $i++) {
            $client_cookie.= chr(self::crypt_random(0, 255));
        }

        $response = $kexinit_payload_server;
        $this->_string_shift($response, 1); // skip past the message number (it should be SSH_MSG_KEXINIT)
        $server_cookie = $this->_string_shift($response, 16);

        $temp = unpack('Nlength', $this->_string_shift($response, 4));
        $this->kex_algorithms = explode(',', $this->_string_shift($response, $temp['length']));

        $temp = unpack('Nlength', $this->_string_shift($response, 4));
        $this->server_host_key_algorithms = explode(',', $this->_string_shift($response, $temp['length']));

        $temp = unpack('Nlength', $this->_string_shift($response, 4));
        $this->encryption_algorithms_client_to_server = explode(',', $this->_string_shift($response, $temp['length']));

        $temp = unpack('Nlength', $this->_string_shift($response, 4));
        $this->encryption_algorithms_server_to_client = explode(',', $this->_string_shift($response, $temp['length']));

        $temp = unpack('Nlength', $this->_string_shift($response, 4));
        $this->mac_algorithms_client_to_server = explode(',', $this->_string_shift($response, $temp['length']));

        $temp = unpack('Nlength', $this->_string_shift($response, 4));
        $this->mac_algorithms_server_to_client = explode(',', $this->_string_shift($response, $temp['length']));

        $temp = unpack('Nlength', $this->_string_shift($response, 4));
        $this->compression_algorithms_client_to_server = explode(',', $this->_string_shift($response, $temp['length']));

        $temp = unpack('Nlength', $this->_string_shift($response, 4));
        $this->compression_algorithms_server_to_client = explode(',', $this->_string_shift($response, $temp['length']));

        $temp = unpack('Nlength', $this->_string_shift($response, 4));
        $this->languages_client_to_server = explode(',', $this->_string_shift($response, $temp['length']));

        $temp = unpack('Nlength', $this->_string_shift($response, 4));
        $this->languages_server_to_client = explode(',', $this->_string_shift($response, $temp['length']));

        extract(unpack('Cfirst_kex_packet_follows', $this->_string_shift($response, 1)));
        $first_kex_packet_follows = $first_kex_packet_follows != 0;

        // the sending of SSH2_MSG_KEXINIT could go in one of two places.  this is the second place.
        $kexinit_payload_client = pack('Ca*Na*Na*Na*Na*Na*Na*Na*Na*Na*Na*CN',
            NET_SSH2_MSG_KEXINIT, $client_cookie, strlen($str_kex_algorithms), $str_kex_algorithms,
            strlen($str_server_host_key_algorithms), $str_server_host_key_algorithms, strlen($encryption_algorithms_client_to_server),
            $encryption_algorithms_client_to_server, strlen($encryption_algorithms_server_to_client), $encryption_algorithms_server_to_client,
            strlen($mac_algorithms_client_to_server), $mac_algorithms_client_to_server, strlen($mac_algorithms_server_to_client),
            $mac_algorithms_server_to_client, strlen($compression_algorithms_client_to_server), $compression_algorithms_client_to_server,
            strlen($compression_algorithms_server_to_client), $compression_algorithms_server_to_client, 0, '', 0, '',
            0, 0
        );

        if (!$this->_send_binary_packet($kexinit_payload_client)) {
            return false;
        }
        // here ends the second place.

        // we need to decide upon the symmetric encryption algorithms before we do the diffie-hellman key exchange
        for ($i = 0; $i < count($encryption_algorithms) && !in_array($encryption_algorithms[$i], $this->encryption_algorithms_server_to_client); $i++);
        if ($i == count($encryption_algorithms)) {
            user_error('No compatible server to client encryption algorithms found', E_USER_NOTICE);
            return $this->_disconnect(NET_SSH2_DISCONNECT_KEY_EXCHANGE_FAILED);
        }

        // we don't initialize any crypto-objects, yet - we do that, later. for now, we need the lengths to make the
        // diffie-hellman key exchange as fast as possible
        $decrypt = $encryption_algorithms[$i];
        switch ($decrypt) {
            case '3des-cbc':
                $decryptKeyLength = 24; // eg. 192 / 8
                break;
            case 'aes256-cbc':
                $decryptKeyLength = 32; // eg. 256 / 8
                break;
            case 'aes192-cbc':
                $decryptKeyLength = 24; // eg. 192 / 8
                break;
            case 'aes128-cbc':
                $decryptKeyLength = 16; // eg. 128 / 8
                break;
            case 'arcfour':
                $decryptKeyLength = 16; // eg. 128 / 8
                break;
            case 'none';
                $decryptKeyLength = 0;
        }

        for ($i = 0; $i < count($encryption_algorithms) && !in_array($encryption_algorithms[$i], $this->encryption_algorithms_client_to_server); $i++);
        if ($i == count($encryption_algorithms)) {
            user_error('No compatible client to server encryption algorithms found', E_USER_NOTICE);
            return $this->_disconnect(NET_SSH2_DISCONNECT_KEY_EXCHANGE_FAILED);
        }

        $encrypt = $encryption_algorithms[$i];
        switch ($encrypt) {
            case '3des-cbc':
                $encryptKeyLength = 24;
                break;
            case 'aes256-cbc':
                $encryptKeyLength = 32;
                break;
            case 'aes192-cbc':
                $encryptKeyLength = 24;
                break;
            case 'aes128-cbc':
                $encryptKeyLength = 16;
                break;
            case 'arcfour':
                $encryptKeyLength = 16;
                break;
            case 'none';
                $encryptKeyLength = 0;
        }

        $keyLength = $decryptKeyLength > $encryptKeyLength ? $decryptKeyLength : $encryptKeyLength;

        // through diffie-hellman key exchange a symmetric key is obtained
        for ($i = 0; $i < count($kex_algorithms) && !in_array($kex_algorithms[$i], $this->kex_algorithms); $i++);
        if ($i == count($kex_algorithms)) {
            user_error('No compatible key exchange algorithms found', E_USER_NOTICE);
            return $this->_disconnect(NET_SSH2_DISCONNECT_KEY_EXCHANGE_FAILED);
        }

        switch ($kex_algorithms[$i]) {
            // see http://tools.ietf.org/html/rfc2409#section-6.2 and 
            // http://tools.ietf.org/html/rfc2412, appendex E
            case 'diffie-hellman-group1-sha1':
                $p = pack('H256', 'FFFFFFFFFFFFFFFFC90FDAA22168C234C4C6628B80DC1CD129024E088A67CC74' . 
                                  '020BBEA63B139B22514A08798E3404DDEF9519B3CD3A431B302B0A6DF25F1437' . 
                                  '4FE1356D6D51C245E485B576625E7EC6F44C42E9A637ED6B0BFF5CB6F406B7ED' . 
                                  'EE386BFB5A899FA5AE9F24117C4B1FE649286651ECE65381FFFFFFFFFFFFFFFF');
                $keyLength = $keyLength < 160 ? $keyLength : 160;
                $hash = 'sha1';
                break;
            // see http://tools.ietf.org/html/rfc3526#section-3
            case 'diffie-hellman-group14-sha1':
                $p = pack('H512', 'FFFFFFFFFFFFFFFFC90FDAA22168C234C4C6628B80DC1CD129024E088A67CC74' . 
                                  '020BBEA63B139B22514A08798E3404DDEF9519B3CD3A431B302B0A6DF25F1437' . 
                                  '4FE1356D6D51C245E485B576625E7EC6F44C42E9A637ED6B0BFF5CB6F406B7ED' . 
                                  'EE386BFB5A899FA5AE9F24117C4B1FE649286651ECE45B3DC2007CB8A163BF05' . 
                                  '98DA48361C55D39A69163FA8FD24CF5F83655D23DCA3AD961C62F356208552BB' . 
                                  '9ED529077096966D670C354E4ABC9804F1746C08CA18217C32905E462E36CE3B' . 
                                  'E39E772C180E86039B2783A2EC07A28FB5C55DF06F4C52C9DE2BCBF695581718' . 
                                  '3995497CEA956AE515D2261898FA051015728E5A8AACAA68FFFFFFFFFFFFFFFF');
                $keyLength = $keyLength < 160 ? $keyLength : 160;
                $hash = 'sha1';
        }

        $p = new BigInteger($p, 256);
        //$q = $p->bitwise_rightShift(1);

        /* To increase the speed of the key exchange, both client and server may
           reduce the size of their private exponents.  It should be at least
           twice as long as the key material that is generated from the shared
           secret.  For more details, see the paper by van Oorschot and Wiener
           [VAN-OORSCHOT].

           -- http://tools.ietf.org/html/rfc4419#section-6.2 */
        $q = new BigInteger(1);
        $q = $q->bitwise_leftShift(2 * $keyLength);
        $q = $q->subtract(new BigInteger(1));

        $g = new BigInteger(2);
        $x = new BigInteger();
        $x->setRandomGenerator(function($a, $b) {
            return SSH2::crypt_random($a, $b);
        });
        $x = $x->random(new BigInteger(1), $q);
        $e = $g->modPow($x, $p);

        $eBytes = $e->toBytes(true);
        $data = pack('CNa*', NET_SSH2_MSG_KEXDH_INIT, strlen($eBytes), $eBytes);

        if (!$this->_send_binary_packet($data)) {
            user_error('Connection closed by server', E_USER_NOTICE);
            return false;
        }

        $response = $this->_get_binary_packet();
        if ($response === false) {
            user_error('Connection closed by server', E_USER_NOTICE);
            return false;
        }
        extract(unpack('Ctype', $this->_string_shift($response, 1)));

        if ($type != NET_SSH2_MSG_KEXDH_REPLY) {
            user_error('Expected SSH_MSG_KEXDH_REPLY', E_USER_NOTICE);
            return false;
        }

        $temp = unpack('Nlength', $this->_string_shift($response, 4));
        $this->server_public_host_key = $server_public_host_key = $this->_string_shift($response, $temp['length']);

        $temp = unpack('Nlength', $this->_string_shift($server_public_host_key, 4));
        $public_key_format = $this->_string_shift($server_public_host_key, $temp['length']);

        $temp = unpack('Nlength', $this->_string_shift($response, 4));
        $fBytes = $this->_string_shift($response, $temp['length']);
        $f = new BigInteger($fBytes, -256);

        $temp = unpack('Nlength', $this->_string_shift($response, 4));
        $signature = $this->_string_shift($response, $temp['length']);

        $temp = unpack('Nlength', $this->_string_shift($signature, 4));
        $signature_format = $this->_string_shift($signature, $temp['length']);

        $key = $f->modPow($x, $p);
        $keyBytes = $key->toBytes(true);

        $source = pack('Na*Na*Na*Na*Na*Na*Na*Na*',
            strlen($this->identifier), $this->identifier, strlen($this->server_identifier), $this->server_identifier,
            strlen($kexinit_payload_client), $kexinit_payload_client, strlen($kexinit_payload_server),
            $kexinit_payload_server, strlen($this->server_public_host_key), $this->server_public_host_key, strlen($eBytes),
            $eBytes, strlen($fBytes), $fBytes, strlen($keyBytes), $keyBytes
        );

        $source = pack('H*', $hash($source));

        if ($this->session_id === false) {
            $this->session_id = $source;
        }

        // if you the server's assymetric key matches the one you have on file, then you should be able to decrypt the
        // "signature" and get something that should equal the "exchange hash", as defined in the SSH-2 specs.
        // here, we just check to see if the "signature" is good.  you can verify whether or not the assymetric key is good,
        // later, with the getServerHostKeyAlgorithm() function
        for ($i = 0; $i < count($server_host_key_algorithms) && !in_array($server_host_key_algorithms[$i], $this->server_host_key_algorithms); $i++);
        if ($i == count($server_host_key_algorithms)) {
            user_error('No compatible server host key algorithms found', E_USER_NOTICE);
            return $this->_disconnect(NET_SSH2_DISCONNECT_KEY_EXCHANGE_FAILED);
        }

        if ($public_key_format != $server_host_key_algorithms[$i] || $signature_format != $server_host_key_algorithms[$i]) {
            user_error('Sever Host Key Algorithm Mismatch', E_USER_NOTICE);
            return $this->_disconnect(NET_SSH2_DISCONNECT_KEY_EXCHANGE_FAILED);
        }

        switch ($server_host_key_algorithms[$i]) {
            case 'ssh-dss':
                $temp = unpack('Nlength', $this->_string_shift($server_public_host_key, 4));
                $p = new BigInteger($this->_string_shift($server_public_host_key, $temp['length']), -256);

                $temp = unpack('Nlength', $this->_string_shift($server_public_host_key, 4));
                $q = new BigInteger($this->_string_shift($server_public_host_key, $temp['length']), -256);

                $temp = unpack('Nlength', $this->_string_shift($server_public_host_key, 4));
                $g = new BigInteger($this->_string_shift($server_public_host_key, $temp['length']), -256);

                $temp = unpack('Nlength', $this->_string_shift($server_public_host_key, 4));
                $y = new BigInteger($this->_string_shift($server_public_host_key, $temp['length']), -256);

                /* The value for 'dss_signature_blob' is encoded as a string containing
                   r, followed by s (which are 160-bit integers, without lengths or
                   padding, unsigned, and in network byte order). */
                $temp = unpack('Nlength', $this->_string_shift($signature, 4));
                if ($temp['length'] != 40) {
                    user_error('Invalid signature', E_USER_NOTICE);
                    return $this->_disconnect(NET_SSH2_DISCONNECT_KEY_EXCHANGE_FAILED);
                }

                $r = new BigInteger($this->_string_shift($signature, 20), 256);
                $s = new BigInteger($this->_string_shift($signature, 20), 256);

                if ($r->compare($q) >= 0 || $s->compare($q) >= 0) {
                    user_error('Invalid signature', E_USER_NOTICE);
                    return $this->_disconnect(NET_SSH2_DISCONNECT_KEY_EXCHANGE_FAILED);
                }

                $w = $s->modInverse($q);

                $u1 = $w->multiply(new BigInteger(sha1($source), 16));
                list(, $u1) = $u1->divide($q);

                $u2 = $w->multiply($r);
                list(, $u2) = $u2->divide($q);

                $g = $g->modPow($u1, $p);
                $y = $y->modPow($u2, $p);

                $v = $g->multiply($y);
                list(, $v) = $v->divide($p);
                list(, $v) = $v->divide($q);

                if (!$v->equals($r)) {
                    user_error('Invalid signature', E_USER_NOTICE);
                    return $this->_disconnect(NET_SSH2_DISCONNECT_HOST_KEY_NOT_VERIFIABLE);
                }

                break;
            case 'ssh-rsa':
                $temp = unpack('Nlength', $this->_string_shift($server_public_host_key, 4));
                $e = new BigInteger($this->_string_shift($server_public_host_key, $temp['length']), -256);

                $temp = unpack('Nlength', $this->_string_shift($server_public_host_key, 4));
                $n = new BigInteger($this->_string_shift($server_public_host_key, $temp['length']), -256);
                $nLength = $temp['length'];

                /*
                $temp = unpack('Nlength', $this->_string_shift($signature, 4));
                $signature = $this->_string_shift($signature, $temp['length']);

                if (!class_exists('Crypt_RSA')) {
                    require_once('Crypt/RSA.php');
                }

                $rsa = new Crypt_RSA();
                $rsa->setSignatureMode(CRYPT_RSA_SIGNATURE_PKCS1);
                $rsa->loadKey(array('e' => $e, 'n' => $n), CRYPT_RSA_PUBLIC_FORMAT_RAW);
                if (!$rsa->verify($source, $signature)) {
                    user_error('Bad server signature', E_USER_NOTICE);
                    return $this->_disconnect(NET_SSH2_DISCONNECT_HOST_KEY_NOT_VERIFIABLE);
                }
                */

                $temp = unpack('Nlength', $this->_string_shift($signature, 4));
                $s = new BigInteger($this->_string_shift($signature, $temp['length']), 256);

                // validate an RSA signature per "8.2 RSASSA-PKCS1-v1_5", "5.2.2 RSAVP1", and "9.1 EMSA-PSS" in the
                // following URL:
                // ftp://ftp.rsasecurity.com/pub/pkcs/pkcs-1/pkcs-1v2-1.pdf

                // also, see SSHRSA.c (rsa2_verifysig) in PuTTy's source.

                if ($s->compare(new BigInteger()) < 0 || $s->compare($n->subtract(new BigInteger(1))) > 0) {
                    user_error('Invalid signature', E_USER_NOTICE);
                    return $this->_disconnect(NET_SSH2_DISCONNECT_KEY_EXCHANGE_FAILED);
                }

                $s = $s->modPow($e, $n);
                $s = $s->toBytes();

                $h = pack('N4H*', 0x00302130, 0x0906052B, 0x0E03021A, 0x05000414, sha1($source));
                $h = chr(0x01) . str_repeat(chr(0xFF), $nLength - 3 - strlen($h)) . $h;

                if ($s != $h) {
                    user_error('Bad server signature', E_USER_NOTICE);
                    return $this->_disconnect(NET_SSH2_DISCONNECT_HOST_KEY_NOT_VERIFIABLE);
                }
        }

        $packet = pack('C',
            NET_SSH2_MSG_NEWKEYS
        );

        if (!$this->_send_binary_packet($packet)) {
            return false;
        }

        $response = $this->_get_binary_packet();

        if ($response === false) {
            user_error('Connection closed by server', E_USER_NOTICE);
            return false;
        }

        extract(unpack('Ctype', $this->_string_shift($response, 1)));

        if ($type != NET_SSH2_MSG_NEWKEYS) {
            user_error('Expected SSH_MSG_NEWKEYS', E_USER_NOTICE);
            return false;
        }

        switch ($encrypt) {
            case '3des-cbc':
                $this->encrypt = new TripleDES();
                // $this->encrypt_block_size = 64 / 8 == the default
                break;
            case 'aes256-cbc':
                $this->encrypt = new AES();
                $this->encrypt_block_size = 16; // eg. 128 / 8
                break;
            case 'aes192-cbc':
                $this->encrypt = new AES();
                $this->encrypt_block_size = 16;
                break;
            case 'aes128-cbc':
                $this->encrypt = new AES();
                $this->encrypt_block_size = 16;
                break;
            case 'arcfour':
                $this->encrypt = new RC4();
                break;
            case 'none';
                //$this->encrypt = new Crypt_Null();
        }

        switch ($decrypt) {
            case '3des-cbc':
                $this->decrypt = new TripleDES();
                break;
            case 'aes256-cbc':
                $this->decrypt = new AES();
                $this->decrypt_block_size = 16;
                break;
            case 'aes192-cbc':
                $this->decrypt = new AES();
                $this->decrypt_block_size = 16;
                break;
            case 'aes128-cbc':
                $this->decrypt = new AES();
                $this->decrypt_block_size = 16;
                break;
            case 'arcfour':
                $this->decrypt = new RC4();
                break;
            case 'none';
                //$this->decrypt = new Crypt_Null();
        }

        $keyBytes = pack('Na*', strlen($keyBytes), $keyBytes);

        if ($this->encrypt) {
            $this->encrypt->enableContinuousBuffer();
            $this->encrypt->disablePadding();

            $iv = pack('H*', $hash($keyBytes . $source . 'A' . $this->session_id));
            while ($this->encrypt_block_size > strlen($iv)) {
                $iv.= pack('H*', $hash($keyBytes . $source . $iv));
            }
            $this->encrypt->setIV(substr($iv, 0, $this->encrypt_block_size));

            $key = pack('H*', $hash($keyBytes . $source . 'C' . $this->session_id));
            while ($encryptKeyLength > strlen($key)) {
                $key.= pack('H*', $hash($keyBytes . $source . $key));
            }
            $this->encrypt->setKey(substr($key, 0, $encryptKeyLength));
        }

        if ($this->decrypt) {
            $this->decrypt->enableContinuousBuffer();
            $this->decrypt->disablePadding();

            $iv = pack('H*', $hash($keyBytes . $source . 'B' . $this->session_id));
            while ($this->decrypt_block_size > strlen($iv)) {
                $iv.= pack('H*', $hash($keyBytes . $source . $iv));
            }
            $this->decrypt->setIV(substr($iv, 0, $this->decrypt_block_size));

            $key = pack('H*', $hash($keyBytes . $source . 'D' . $this->session_id));
            while ($decryptKeyLength > strlen($key)) {
                $key.= pack('H*', $hash($keyBytes . $source . $key));
            }
            $this->decrypt->setKey(substr($key, 0, $decryptKeyLength));
        }

        for ($i = 0; $i < count($mac_algorithms) && !in_array($mac_algorithms[$i], $this->mac_algorithms_client_to_server); $i++);
        if ($i == count($mac_algorithms)) {
            user_error('No compatible client to server message authentication algorithms found', E_USER_NOTICE);
            return $this->_disconnect(NET_SSH2_DISCONNECT_KEY_EXCHANGE_FAILED);
        }

        $createKeyLength = 0; // ie. $mac_algorithms[$i] == 'none'
        switch ($mac_algorithms[$i]) {
            case 'hmac-sha1':
                $this->hmac_create = new Hash('sha1');
                $createKeyLength = 20;
                break;
            case 'hmac-sha1-96':
                $this->hmac_create = new Hash('sha1-96');
                $createKeyLength = 20;
                break;
            case 'hmac-md5':
                $this->hmac_create = new Hash('md5');
                $createKeyLength = 16;
                break;
            case 'hmac-md5-96':
                $this->hmac_create = new Hash('md5-96');
                $createKeyLength = 16;
        }

        for ($i = 0; $i < count($mac_algorithms) && !in_array($mac_algorithms[$i], $this->mac_algorithms_server_to_client); $i++);
        if ($i == count($mac_algorithms)) {
            user_error('No compatible server to client message authentication algorithms found', E_USER_NOTICE);
            return $this->_disconnect(NET_SSH2_DISCONNECT_KEY_EXCHANGE_FAILED);
        }

        $checkKeyLength = 0;
        $this->hmac_size = 0;
        switch ($mac_algorithms[$i]) {
            case 'hmac-sha1':
                $this->hmac_check = new Hash('sha1');
                $checkKeyLength = 20;
                $this->hmac_size = 20;
                break;
            case 'hmac-sha1-96':
                $this->hmac_check = new Hash('sha1-96');
                $checkKeyLength = 20;
                $this->hmac_size = 12;
                break;
            case 'hmac-md5':
                $this->hmac_check = new Hash('md5');
                $checkKeyLength = 16;
                $this->hmac_size = 16;
                break;
            case 'hmac-md5-96':
                $this->hmac_check = new Hash('md5-96');
                $checkKeyLength = 16;
                $this->hmac_size = 12;
        }

        $key = pack('H*', $hash($keyBytes . $source . 'E' . $this->session_id));
        while ($createKeyLength > strlen($key)) {
            $key.= pack('H*', $hash($keyBytes . $source . $key));
        }
        $this->hmac_create->setKey(substr($key, 0, $createKeyLength));

        $key = pack('H*', $hash($keyBytes . $source . 'F' . $this->session_id));
        while ($checkKeyLength > strlen($key)) {
            $key.= pack('H*', $hash($keyBytes . $source . $key));
        }
        $this->hmac_check->setKey(substr($key, 0, $checkKeyLength));

        for ($i = 0; $i < count($compression_algorithms) && !in_array($compression_algorithms[$i], $this->compression_algorithms_server_to_client); $i++);
        if ($i == count($compression_algorithms)) {
            user_error('No compatible server to client compression algorithms found', E_USER_NOTICE);
            return $this->_disconnect(NET_SSH2_DISCONNECT_KEY_EXCHANGE_FAILED);
        }
        $this->decompress = $compression_algorithms[$i] == 'zlib';

        for ($i = 0; $i < count($compression_algorithms) && !in_array($compression_algorithms[$i], $this->compression_algorithms_client_to_server); $i++);
        if ($i == count($compression_algorithms)) {
            user_error('No compatible client to server compression algorithms found', E_USER_NOTICE);
            return $this->_disconnect(NET_SSH2_DISCONNECT_KEY_EXCHANGE_FAILED);
        }
        $this->compress = $compression_algorithms[$i] == 'zlib';

        return true;
    }

    /**
     * Login
     *
     * @param String $username
     * @param optional String $password
     * @return Boolean
     * @access public
     * @internal It might be worthwhile, at some point, to protect against {@link http://tools.ietf.org/html/rfc4251#section-9.3.9 traffic analysis}
     *           by sending dummy SSH_MSG_IGNORE messages.
     */
    function login($username, $password = '')
    {
        if (!($this->bitmap & NET_SSH2_MASK_CONSTRUCTOR)) {
//var_dump('1233');
            return false;
        }

        $packet = pack('CNa*',
            NET_SSH2_MSG_SERVICE_REQUEST, strlen('ssh-userauth'), 'ssh-userauth'
        );

        if (!$this->_send_binary_packet($packet)) {
//var_dump('1243');
            return false;
        }
//var_dump('1245');

        $response = $this->_get_binary_packet();
        if ($response === false) {
            user_error('Connection closed by server', E_USER_NOTICE);
            return false;
        }

        extract(unpack('Ctype', $this->_string_shift($response, 1)));

        if ($type != NET_SSH2_MSG_SERVICE_ACCEPT) {
            user_error('Expected SSH_MSG_SERVICE_ACCEPT', E_USER_NOTICE);
            return false;
        }

        // although PHP5's get_class() preserves the case, PHP4's does not
        
        if (strtolower(get_class($password)) == 'phpseclib\crypt\rsa') {
            return $this->_privatekey_login($username, $password);
        }
        
        $utf8_password = utf8_encode($password);
        $packet = pack('CNa*Na*Na*CNa*',
            NET_SSH2_MSG_USERAUTH_REQUEST, strlen($username), $username, strlen('ssh-connection'), 'ssh-connection',
            strlen('password'), 'password', 0, strlen($utf8_password), $utf8_password
        );

        if (!$this->_send_binary_packet($packet)) {
            return false;
        }

        // remove the username and password from the last logged packet
        if (defined('NET_SSH2_LOGGING')) {
            $packet = pack('CNa*Na*Na*CNa*',
                NET_SSH2_MSG_USERAUTH_REQUEST, strlen('username'), 'username', strlen('ssh-connection'), 'ssh-connection',
                strlen('password'), 'password', 0, strlen('password'), 'password'
            );
            $this->message_log[count($this->message_log) - 1] = $packet;
        }

        $response = $this->_get_binary_packet();
        if ($response === false) {
            user_error('Connection closed by server', E_USER_NOTICE);
            return false;
        }

        extract(unpack('Ctype', $this->_string_shift($response, 1)));

        switch ($type) {
            case NET_SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ: // in theory, the password can be changed
                if (defined('NET_SSH2_LOGGING')) {
                    $this->message_number_log[count($this->message_number_log) - 1] = 'NET_SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ';
                }
                extract(unpack('Nlength', $this->_string_shift($response, 4)));
                $this->debug_info.= "\r\n\r\nSSH_MSG_USERAUTH_PASSWD_CHANGEREQ:\r\n" . utf8_decode($this->_string_shift($response, $length));
                return $this->_disconnect(NET_SSH2_DISCONNECT_AUTH_CANCELLED_BY_USER);
            case NET_SSH2_MSG_USERAUTH_FAILURE:
                // either the login is bad or the server employees multi-factor authentication
                return false;
            case NET_SSH2_MSG_USERAUTH_SUCCESS:
                $this->bitmap |= NET_SSH2_MASK_LOGIN;
                return true;
        }

        return false;
    }

    /**
     * Login with an RSA private key
     *
     * @param String $username
     * @param Crypt_RSA $password
     * @return Boolean
     * @access private
     * @internal It might be worthwhile, at some point, to protect against {@link http://tools.ietf.org/html/rfc4251#section-9.3.9 traffic analysis}
     *           by sending dummy SSH_MSG_IGNORE messages.
     */
    function _privatekey_login($username, $privatekey)
    {
        // see http://tools.ietf.org/html/rfc4253#page-15
        $publickey = $privatekey->getPublicKey(CRYPT_RSA_PUBLIC_FORMAT_RAW);
        $publickey = array(
            'e' => $publickey['e']->toBytes(true),
            'n' => $publickey['n']->toBytes(true)
        );
        $publickey = pack('Na*Na*Na*',
            strlen('ssh-rsa'), 'ssh-rsa', strlen($publickey['e']), $publickey['e'], strlen($publickey['n']), $publickey['n']
        );

        $part1 = pack('CNa*Na*Na*',
            NET_SSH2_MSG_USERAUTH_REQUEST, strlen($username), $username, strlen('ssh-connection'), 'ssh-connection',
            strlen('publickey'), 'publickey'
        );
        $part2 = pack('Na*Na*', strlen('ssh-rsa'), 'ssh-rsa', strlen($publickey), $publickey);

        $packet = $part1 . chr(0) . $part2;

        if (!$this->_send_binary_packet($packet)) {
            return false;
        }

        $response = $this->_get_binary_packet();
        if ($response === false) {
            user_error('Connection closed by server', E_USER_NOTICE);
            return false;
        }

        extract(unpack('Ctype', $this->_string_shift($response, 1)));

        switch ($type) {
            case NET_SSH2_MSG_USERAUTH_FAILURE:
                extract(unpack('Nlength', $this->_string_shift($response, 4)));
                $this->debug_info.= "\r\n\r\nSSH_MSG_USERAUTH_FAILURE:\r\n" . $this->_string_shift($response, $length);
                return $this->_disconnect(NET_SSH2_DISCONNECT_AUTH_CANCELLED_BY_USER);
            case NET_SSH2_MSG_USERAUTH_PK_OK:
                // we'll just take it on faith that the public key blob and the public key algorithm name are as
                // they should be
               …