<?php

namespace MailPoetVendor;

if (!defined('ABSPATH')) exit;


/*
 * 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.
 */
/**
 * Handles CRAM-MD5 authentication.
 *
 * @author Chris Corbyn
 */
class Swift_Transport_Esmtp_Auth_CramMd5Authenticator implements \MailPoetVendor\Swift_Transport_Esmtp_Authenticator
{
    /**
     * Get the name of the AUTH mechanism this Authenticator handles.
     *
     * @return string
     */
    public function getAuthKeyword()
    {
        return 'CRAM-MD5';
    }
    /**
     * {@inheritdoc}
     */
    public function authenticate(\MailPoetVendor\Swift_Transport_SmtpAgent $agent, $username, $password)
    {
        try {
            $challenge = $agent->executeCommand("AUTH CRAM-MD5\r\n", [334]);
            $challenge = \base64_decode(\substr($challenge, 4));
            $message = \base64_encode($username . ' ' . $this->getResponse($password, $challenge));
            $agent->executeCommand(\sprintf("%s\r\n", $message), [235]);
            return \true;
        } catch (\MailPoetVendor\Swift_TransportException $e) {
            $agent->executeCommand("RSET\r\n", [250]);
            throw $e;
        }
    }
    /**
     * Generate a CRAM-MD5 response from a server challenge.
     *
     * @param string $secret
     * @param string $challenge
     *
     * @return string
     */
    private function getResponse($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;
    }
}
