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   1  <?php
   2  
   3  /*
   4   * This file is part of SwiftMailer.
   5   * (c) 2004-2009 Chris Corbyn
   6   *
   7   * For the full copyright and license information, please view the LICENSE
   8   * file that was distributed with this source code.
   9   */
  10  
  11  /**
  12   * Handles CRAM-MD5 authentication.
  13   *
  14   * @author Chris Corbyn
  15   */
  16  class Swift_Transport_Esmtp_Auth_CramMd5Authenticator implements Swift_Transport_Esmtp_Authenticator
  17  {
  18      /**
  19       * Get the name of the AUTH mechanism this Authenticator handles.
  20       *
  21       * @return string
  22       */
  23      public function getAuthKeyword()
  24      {
  25          return 'CRAM-MD5';
  26      }
  27  
  28      /**
  29       * {@inheritdoc}
  30       */
  31      public function authenticate(Swift_Transport_SmtpAgent $agent, $username, $password)
  32      {
  33          try {
  34              $challenge = $agent->executeCommand("AUTH CRAM-MD5\r\n", [334]);
  35              $challenge = base64_decode(substr($challenge, 4));
  36              $message = base64_encode(
  37                  $username.' '.$this->getResponse($password, $challenge)
  38                  );
  39              $agent->executeCommand(sprintf("%s\r\n", $message), [235]);
  40  
  41              return true;
  42          } catch (Swift_TransportException $e) {
  43              $agent->executeCommand("RSET\r\n", [250]);
  44  
  45              throw $e;
  46          }
  47      }
  48  
  49      /**
  50       * Generate a CRAM-MD5 response from a server challenge.
  51       *
  52       * @param string $secret
  53       * @param string $challenge
  54       *
  55       * @return string
  56       */
  57      private function getResponse($secret, $challenge)
  58      {
  59          if (strlen($secret) > 64) {
  60              $secret = pack('H32', md5($secret));
  61          }
  62  
  63          if (strlen($secret) < 64) {
  64              $secret = str_pad($secret, 64, chr(0));
  65          }
  66  
  67          $k_ipad = substr($secret, 0, 64) ^ str_repeat(chr(0x36), 64);
  68          $k_opad = substr($secret, 0, 64) ^ str_repeat(chr(0x5C), 64);
  69  
  70          $inner = pack('H32', md5($k_ipad.$challenge));
  71          $digest = md5($k_opad.$inner);
  72  
  73          return $digest;
  74      }
  75  }