CramMd5Authenticator.php

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<?php

/*
 * This file is part of SwiftMailer.
 * (c) 2004-2009 Chris Corbyn
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

//@require 'Swift/Transport/Esmtp/Authenticator.php';
//@require 'Swift/Transport/SmtpAgent.php';
//@require 'Swift/TransportException.php';

class Swift_Transport_Esmtp_Auth_CramMd5Authenticator
  implements Swift_Transport_Esmtp_Authenticator
{
  
  public function getAuthKeyword()
  {
    return 'CRAM-MD5';
  }
  
  public function authenticate(Swift_Transport_SmtpAgent $agent,
    $username, $password)
  {
    try
    {
      $challenge = $agent->executeCommand("AUTH CRAM-MD5\r\n", array(334));
      $challenge = base64_decode(substr($challenge, 4));
      $message = base64_encode(
        $username . ' ' . $this->_getResponse($password, $challenge)
        );
      $agent->executeCommand(sprintf("%s\r\n", $message), array(235));
      return true;
    }
    catch (Swift_TransportException $e)
    {
      $agent->executeCommand("RSET\r\n", array(250));
      return false;
    }
  }
  
  private function _getResponse($secret, $challenge)
  {
    if (strlen($secret) > 64)
    {
      $secret = pack('H32', md5($secret));
    }
    
    if (strlen($secret) < 64)
    {
      $secret = str_pad($secret, 64, chr(0));
    }
    
    $k_ipad = substr($secret, 0, 64) ^ str_repeat(chr(0x36), 64);
    $k_opad = substr($secret, 0, 64) ^ str_repeat(chr(0x5C), 64);

    $inner  = pack('H32', md5($k_ipad . $challenge));
    $digest = md5($k_opad . $inner);

    return $digest;
  }
  
}