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<?php
/**
* Pure-PHP ssh-agent client.
*
* PHP version 5
*
* @category System
* @package SSH\Agent
* @author Jim Wigginton <terrafrost@php.net>
* @copyright 2009 Jim Wigginton
* @license http://www.opensource.org/licenses/mit-license.html MIT License
* @link http://phpseclib.sourceforge.net
* @internal See http://api.libssh.org/rfc/PROTOCOL.agent
*/
namespace phpseclib\System\SSH\Agent;
use phpseclib\System\SSH\Agent;
/**
* Pure-PHP ssh-agent client identity object
*
* Instantiation should only be performed by \phpseclib\System\SSH\Agent class.
* This could be thought of as implementing an interface that phpseclib\Crypt\RSA
* implements. ie. maybe a Net_SSH_Auth_PublicKey interface or something.
* The methods in this interface would be getPublicKey and sign since those are the
* methods phpseclib looks for to perform public key authentication.
*
* @package SSH\Agent
* @author Jim Wigginton <terrafrost@php.net>
* @access internal
*/
class Identity
{
/**@+
* Signature Flags
*
* See https://tools.ietf.org/html/draft-miller-ssh-agent-00#section-5.3
*
* @access private
*/
const SSH_AGENT_RSA2_256 = 2;
const SSH_AGENT_RSA2_512 = 4;
/**#@-*/
/**
* Key Object
*
* @var \phpseclib\Crypt\RSA
* @access private
* @see self::getPublicKey()
*/
var $key;
/**
* Key Blob
*
* @var string
* @access private
* @see self::sign()
*/
var $key_blob;
/**
* Socket Resource
*
* @var resource
* @access private
* @see self::sign()
*/
var $fsock;
/**
* Signature flags
*
* @var int
* @access private
* @see self::sign()
* @see self::setHash()
*/
var $flags = 0;
/**
* Default Constructor.
*
* @param resource $fsock
* @return \phpseclib\System\SSH\Agent\Identity
* @access private
*/
function __construct($fsock)
{
$this->fsock = $fsock;
}
/**
* Set Public Key
*
* Called by \phpseclib\System\SSH\Agent::requestIdentities()
*
* @param \phpseclib\Crypt\RSA $key
* @access private
*/
function setPublicKey($key)
{
$this->key = $key;
$this->key->setPublicKey();
}
/**
* Set Public Key
*
* Called by \phpseclib\System\SSH\Agent::requestIdentities(). The key blob could be extracted from $this->key
* but this saves a small amount of computation.
*
* @param string $key_blob
* @access private
*/
function setPublicKeyBlob($key_blob)
{
$this->key_blob = $key_blob;
}
/**
* Get Public Key
*
* Wrapper for $this->key->getPublicKey()
*
* @param int $format optional
* @return mixed
* @access public
*/
function getPublicKey($format = null)
{
return !isset($format) ? $this->key->getPublicKey() : $this->key->getPublicKey($format);
}
/**
* Set Signature Mode
*
* Doesn't do anything as ssh-agent doesn't let you pick and choose the signature mode. ie.
* ssh-agent's only supported mode is \phpseclib\Crypt\RSA::SIGNATURE_PKCS1
*
* @param int $mode
* @access public
*/
function setSignatureMode($mode)
{
}
/**
* Set Hash
*
* ssh-agent doesn't support using hashes for RSA other than SHA1
*
* @param string $hash
* @access public
*/
function setHash($hash)
{
$this->flags = 0;
switch ($hash) {
case 'sha1':
break;
case 'sha256':
$this->flags = self::SSH_AGENT_RSA2_256;
break;
case 'sha512':
$this->flags = self::SSH_AGENT_RSA2_512;
break;
default:
user_error('The only supported hashes for RSA are sha1, sha256 and sha512');
}
}
/**
* Create a signature
*
* See "2.6.2 Protocol 2 private key signature request"
*
* @param string $message
* @return string
* @access public
*/
function sign($message)
{
// the last parameter (currently 0) is for flags and ssh-agent only defines one flag (for ssh-dss): SSH_AGENT_OLD_SIGNATURE
$packet = pack('CNa*Na*N', Agent::SSH_AGENTC_SIGN_REQUEST, strlen($this->key_blob), $this->key_blob, strlen($message), $message, $this->flags);
$packet = pack('Na*', strlen($packet), $packet);
if (strlen($packet) != fputs($this->fsock, $packet)) {
user_error('Connection closed during signing');
return false;
}
$temp = fread($this->fsock, 4);
if (strlen($temp) != 4) {
user_error('Connection closed during signing');
return false;
}
$length = current(unpack('N', $temp));
$type = ord(fread($this->fsock, 1));
if ($type != Agent::SSH_AGENT_SIGN_RESPONSE) {
user_error('Unable to retrieve signature');
return false;
}
$signature_blob = fread($this->fsock, $length - 1);
if (strlen($signature_blob) != $length - 1) {
user_error('Connection closed during signing');
return false;
}
$length = current(unpack('N', $this->_string_shift($signature_blob, 4)));
if ($length != strlen($signature_blob)) {
user_error('Malformed signature blob');
}
$length = current(unpack('N', $this->_string_shift($signature_blob, 4)));
if ($length > strlen($signature_blob) + 4) {
user_error('Malformed signature blob');
}
$type = $this->_string_shift($signature_blob, $length);
$this->_string_shift($signature_blob, 4);
return $signature_blob;
}
/**
* String Shift
*
* Inspired by array_shift
*
* @param string $string
* @param int $index
* @return string
* @access private
*/
function _string_shift(&$string, $index = 1)
{
$substr = substr($string, 0, $index);
$string = substr($string, $index);
return $substr;
}
}
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