library/phpseclib/Crypt/Random.php

   1 <?php
   2 /* vim: set expandtab tabstop=4 shiftwidth=4 softtabstop=4: */
   3
   4 /**
   5  * Random Number Generator
   6  *
   7  * PHP versions 4 and 5
   8  *
   9  * Here's a short example of how to use this library:
  10  * <code>
  11  * <?php
  12  *    include('Crypt/Random.php');
  13  *
  14  *    echo crypt_random();
  15  * ?>
  16  * </code>
  17  *
  18  * LICENSE: Permission is hereby granted, free of charge, to any person obtaining a copy
  19  * of this software and associated documentation files (the "Software"), to deal
  20  * in the Software without restriction, including without limitation the rights
  21  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  22  * copies of the Software, and to permit persons to whom the Software is
  23  * furnished to do so, subject to the following conditions:
  24  *
  25  * The above copyright notice and this permission notice shall be included in
  26  * all copies or substantial portions of the Software.
  27  *
  28  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  29  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  30  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  31  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  32  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  33  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  34  * THE SOFTWARE.
  35  *
  36  * @category   Crypt
  37  * @package    Crypt_Random
  38  * @author     Jim Wigginton <terrafrost@php.net>
  39  * @copyright  MMVII Jim Wigginton
  40  * @license    http://www.opensource.org/licenses/mit-license.html  MIT License
  41  * @version    $Id: Random.php,v 1.9 2010/04/24 06:40:48 terrafrost Exp $
  42  * @link       http://phpseclib.sourceforge.net
  43  */
  44
  45 /**
  46  * Generate a random value.
  47  *
  48  * On 32-bit machines, the largest distance that can exist between $min and $max is 2**31.
  49  * If $min and $max are farther apart than that then the last ($max - range) numbers.
  50  *
  51  * Depending on how this is being used, it may be worth while to write a replacement.  For example,
  52  * a PHP-based web app that stores its data in an SQL database can collect more entropy than this function
  53  * can.
  54  *
  55  * @param optional Integer $min
  56  * @param optional Integer $max
  57  * @return Integer
  58  * @access public
  59  */
  60 function crypt_random($min = 0, $max = 0x7FFFFFFF)
  61 {
  62     if ($min == $max) {
  63         return $min;
  64     }
  65
  66     if (function_exists('openssl_random_pseudo_bytes')) {
  67         // openssl_random_pseudo_bytes() is slow on windows per the following:
  68         // http://stackoverflow.com/questions/1940168/openssl-random-pseudo-bytes-is-slow-php
  69         if ((PHP_OS & "\xDF\xDF\xDF") !== 'WIN') { // PHP_OS & "\xDF\xDF\xDF" == strtoupper(substr(PHP_OS, 0, 3)), but a lot faster
  70             extract(unpack('Nrandom', openssl_random_pseudo_bytes(4)));
  71
  72             return abs($random) % ($max - $min) + $min;
  73         }
  74     }
  75
  76     // see http://en.wikipedia.org/wiki//dev/random
  77     static $urandom = true;
  78     if ($urandom === true) {
  79         // Warning's will be output unles the error suppression operator is used.  Errors such as
  80         // "open_basedir restriction in effect", "Permission denied", "No such file or directory", etc.
  81         $urandom = @fopen('/dev/urandom', 'rb');
  82     }
  83     if (!is_bool($urandom)) {
  84         extract(unpack('Nrandom', fread($urandom, 4)));
  85
  86         // say $min = 0 and $max = 3.  if we didn't do abs() then we could have stuff like this:
  87         // -4 % 3 + 0 = -1, even though -1 < $min
  88         return abs($random) % ($max - $min) + $min;
  89     }
  90
  91     /* Prior to PHP 4.2.0, mt_srand() had to be called before mt_rand() could be called.
  92        Prior to PHP 5.2.6, mt_rand()'s automatic seeding was subpar, as elaborated here:
  93
  94        http://www.suspekt.org/2008/08/17/mt_srand-and-not-so-random-numbers/
  95
  96        The seeding routine is pretty much ripped from PHP's own internal GENERATE_SEED() macro:
  97
  98        http://svn.php.net/viewvc/php/php-src/tags/php_5_3_2/ext/standard/php_rand.h?view=markup */
  99     if (version_compare(PHP_VERSION, '5.2.5', '<=')) {
 100         static $seeded;
 101         if (!isset($seeded)) {
 102             $seeded = true;
 103             mt_srand(fmod(time() * getmypid(), 0x7FFFFFFF) ^ fmod(1000000 * lcg_value(), 0x7FFFFFFF));
 104         }
 105     }
 106
 107     static $crypto;
 108
 109     // The CSPRNG's Yarrow and Fortuna periodically reseed.  This function can be reseeded by hitting F5
 110     // in the browser and reloading the page.
 111
 112     if (!isset($crypto)) {
 113         $key = $iv = '';
 114         for ($i = 0; $i < 8; $i++) {
 115             $key.= pack('n', mt_rand(0, 0xFFFF));
 116             $iv .= pack('n', mt_rand(0, 0xFFFF));
 117         }
 118         switch (true) {
 119             case class_exists('Crypt_AES'):
 120                 $crypto = new Crypt_AES(CRYPT_AES_MODE_CTR);
 121                 break;
 122             case class_exists('Crypt_TripleDES'):
 123                 $crypto = new Crypt_TripleDES(CRYPT_DES_MODE_CTR);
 124                 break;
 125             case class_exists('Crypt_DES'):
 126                 $crypto = new Crypt_DES(CRYPT_DES_MODE_CTR);
 127                 break;
 128             case class_exists('Crypt_RC4'):
 129                 $crypto = new Crypt_RC4();
 130                 break;
 131             default:
 132                 extract(unpack('Nrandom', pack('H*', sha1(mt_rand(0, 0x7FFFFFFF)))));
 133                 return abs($random) % ($max - $min) + $min;
 134         }
 135         $crypto->setKey($key);
 136         $crypto->setIV($iv);
 137         $crypto->enableContinuousBuffer();
 138     }
 139
 140     extract(unpack('Nrandom', $crypto->encrypt("\0\0\0\0")));
 141     return abs($random) % ($max - $min) + $min;
 142 }