<?php
// +-----------------------------------------------------------------------+ 
// | Copyright (c) 2002-2003 Richard Heyes                                 | 
// | All rights reserved.                                                  | 
// |                                                                       | 
// | Redistribution and use in source and binary forms, with or without    | 
// | modification, are permitted provided that the following conditions    | 
// | are met:                                                              | 
// |                                                                       | 
// | o Redistributions of source code must retain the above copyright      | 
// |   notice, this list of conditions and the following disclaimer.       | 
// | o Redistributions in binary form must reproduce the above copyright   | 
// |   notice, this list of conditions and the following disclaimer in the | 
// |   documentation and/or other materials provided with the distribution.| 
// | o The names of the authors may not be used to endorse or promote      | 
// |   products derived from this software without specific prior written  | 
// |   permission.                                                         | 
// |                                                                       | 
// | THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS   | 
// | "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT     | 
// | LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR | 
// | A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT  | 
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// |                                                                       | 
// +-----------------------------------------------------------------------+ 
// | Author: Richard Heyes <richard@php.net>                               | 
// +-----------------------------------------------------------------------+ 
// 
// $Id: Common.php 17 2005-10-03 20:25:31Z roundcube $

/**
* Common functionality to SASL mechanisms
*
* @author  Richard Heyes <richard@php.net>
* @access  public
* @version 1.0
* @package Auth_SASL
*/

class Auth_SASL_Common
{
    /**
    * Function which implements HMAC MD5 digest
    *
    * @param  string $key  The secret key
    * @param  string $data The data to protect
    * @return string       The HMAC MD5 digest
    */
    function _HMAC_MD5($key, $data)
    {
        if (strlen($key) > 64) {
            $key = pack('H32', md5($key));
        }

        if (strlen($key) < 64) {
            $key = str_pad($key, 64, chr(0));
        }

        $k_ipad = substr($key, 0, 64) ^ str_repeat(chr(0x36), 64);
        $k_opad = substr($key, 0, 64) ^ str_repeat(chr(0x5C), 64);

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

        return $digest;
    }
}
?>