CryptLib/Random/Source/URandom.php

   1 <?php
   2 /**
   3  * The URandom Random Number Source
   4  *
   5  * This uses the *nix /dev/urandom device to generate medium strength numbers
   6  *
   7  * PHP version 5.3
   8  *
   9  * @category   PHPCryptLib
  10  * @package    Random
  11  * @subpackage Source
  12  * @author     Anthony Ferrara <ircmaxell@ircmaxell.com>
  13  * @copyright  2011 The Authors
  14  * @license    http://www.opensource.org/licenses/mit-license.html  MIT License
  15  * @version    Build @@version@@
  16  */
  17
  18 namespace CryptLib\Random\Source;
  19
  20 use CryptLib\Core\Strength;
  21
  22 /**
  23  * The URandom Random Number Source
  24  *
  25  * This uses the *nix /dev/urandom device to generate medium strength numbers
  26  *
  27  * @category   PHPCryptLib
  28  * @package    Random
  29  * @subpackage Source
  30  * @author     Anthony Ferrara <ircmaxell@ircmaxell.com>
  31  * @codeCoverageIgnore
  32  */
  33 class URandom implements \CryptLib\Random\Source {
  34
  35     /**
  36      * @var string The file to read from
  37      */
  38     protected $file = '/dev/urandom';
  39
  40     /**
  41      * Return an instance of Strength indicating the strength of the source
  42      *
  43      * @return Strength An instance of one of the strength classes
  44      */
  45     public static function getStrength() {
  46         return new Strength(Strength::MEDIUM);
  47     }
  48
  49     /**
  50      * Generate a random string of the specified size
  51      *
  52      * @param int $size The size of the requested random string
  53      *
  54      * @return string A string of the requested size
  55      */
  56     public function generate($size) {
  57         if ($size == 0 || !file_exists($this->file)) {
  58             return str_repeat(chr(0), $size);
  59         }
  60         $file = fopen($this->file, 'rb');
  61         if (!$file) {
  62             return str_repeat(chr(0), $size);
  63         }
  64         if (function_exists('stream_set_read_buffer')) {
  65             stream_set_read_buffer($file, 0);
  66         }
  67         $result = fread($file, $size);
  68         fclose($file);
  69         return $result;
  70     }
  71
  72 }