LoomRandom.php

   1 <?php
   2
   3   // Cryptographically secure random number generation
   4
   5 class LoomRandom {
   6
   7   var $urandom_filehandle;      // /dev/urandom file handle
   8   var $use_urandom;             // false if we can't open /dev/urandom
   9
  10   function LoomRandom() {
  11     $this->urandom_filehandle = false;
  12     $this->use_urandom = true;
  13   }
  14
  15   // Return $num random bytes from /dev/urandom
  16   function urandom_bytes($num) {
  17     if ($num < 0)
  18       err("NUM must be nonnegative in urandom_bytes");
  19     if ($this->use_urandom && !$this->urandom_filehandle) {
  20       $file = @fopen("/dev/urandom", "r");
  21       if (!$file) $this->use_urandom = false;
  22       else $this->urandom_filehandle = $file;
  23     }
  24     $res = '';
  25     if ($this->use_urandom) {
  26       while (strlen($res) < $num) {
  27         $res .= fread($this->urandom_filehandle, $num - strlen($res));
  28       }
  29     } else {
  30       for ($i=0; $i<$num; $i++) {
  31         $res .= chr(mt_rand(0, 255));
  32       }
  33     }
  34     return $res;
  35   }
  36
  37   // Return a random 128-bit location, as hex
  38   function random_id() {
  39     $res = bin2hex($this->urandom_bytes(16));
  40     if (strlen($res) < 32) $res = str_repeat("0", 32 - strlen($res)) . $res;
  41     return $res;
  42   }
  43
  44 }
  45
  46 /* testing code
  47
  48 $random = new LoomRandom();
  49 echo $random->random_id() . "\n";
  50
  51 */
  52
  53 /* ***** BEGIN LICENSE BLOCK *****
  54  * Version: MPL 1.1/GPL 2.0/LGPL 2.1/Apache 2.0
  55  *
  56  * The contents of this file are subject to the Mozilla Public License Version
  57  * 1.1 (the "License"); you may not use this file except in compliance with
  58  * the License. You may obtain a copy of the License at
  59  * http://www.mozilla.org/MPL/
  60  *
  61  * Software distributed under the License is distributed on an "AS IS" basis,
  62  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
  63  * for the specific language governing rights and limitations under the
  64  * License.
  65  *
  66  * The Original Code is LoomClient PHP library
  67  *
  68  * The Initial Developer of the Original Code is
  69  * Bill St. Clair.
  70  * Portions created by the Initial Developer are Copyright (C) 2008
  71  * the Initial Developer. All Rights Reserved.
  72  *
  73  * Contributor(s):
  74  *   Bill St. Clair <bill@billstclair.com>
  75  *
  76  * Alternatively, the contents of this file may be used under the
  77  * terms of the GNU General Public License Version 2 or later (the
  78  * "GPL"), the GNU Lesser General Public License Version 2.1 or later
  79  * (the "LGPL"), or The Apache License Version 2.0 (the "AL"), in
  80  * which case the provisions of the GPL, LGPL, or AL are applicable
  81  * instead of those above. If you wish to allow use of your version of
  82  * this file only under the terms of the GPL, the LGPL, or the AL, and
  83  * not to allow others to use your version of this file under the
  84  * terms of the MPL, indicate your decision by deleting the provisions
  85  * above and replace them with the notice and other provisions
  86  * required by the GPL or the LGPL. If you do not delete the
  87  * provisions above, a recipient may use your version of this file
  88  * under the terms of any one of the MPL, the GPL the LGPL, or the AL.
  89  ****** END LICENSE BLOCK ***** */
  90 ?>