<?php
/* vim: set expandtab tabstop=4 shiftwidth=4 softtabstop=4: */
/**
* Random Number Generator
*
* PHP versions 4 and 5
*
* Here's a short example of how to use this library:
* <code>
* <?php
* include('Crypt/Random.php');
*
* echo crypt_random();
* ?>
* </code>
*
* LICENSE: This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
* MA 02111-1307 USA
*
* @category Crypt
* @package Crypt_Random
* @author Jim Wigginton <terrafrost@php.net>
* @copyright MMVII Jim Wigginton
* @license http://www.gnu.org/licenses/lgpl.txt
* @version $Id: Random.php,v 1.9 2010/04/24 06:40:48 terrafrost Exp $
* @link http://phpseclib.sourceforge.net
*/
/**
* Generate a random value.
*
* On 32-bit machines, the largest distance that can exist between $min and $max is 2**31.
* If $min and $max are farther apart than that then the last ($max - range) numbers.
*
* Depending on how this is being used, it may be worth while to write a replacement. For example,
* a PHP-based web app that stores its data in an SQL database can collect more entropy than this function
* can.
*
* @param optional Integer $min
* @param optional Integer $max
* @return Integer
* @access public
*/
function crypt_random($min = 0, $max = 0x7FFFFFFF)
{
if ($min == $max) {
return $min;
}
// see http://en.wikipedia.org/wiki//dev/random
// if open_basedir is enabled file_exists() will ouput an "open_basedir restriction in effect" warning,
// so we suppress it.
if (@file_exists('/dev/urandom')) {
static $fp;
if (!$fp) {
$fp = fopen('/dev/urandom', 'rb');
}
extract(unpack('Nrandom', fread($fp, 4)));
// say $min = 0 and $max = 3. if we didn't do abs() then we could have stuff like this:
// -4 % 3 + 0 = -1, even though -1 < $min
return abs($random) % ($max - $min) + $min;
}
/* Prior to PHP 4.2.0, mt_srand() had to be called before mt_rand() could be called.
Prior to PHP 5.2.6, mt_rand()'s automatic seeding was subpar, as elaborated here:
http://www.suspekt.org/2008/08/17/mt_srand-and-not-so-random-numbers/
The seeding routine is pretty much ripped from PHP's own internal GENERATE_SEED() macro:
http://svn.php.net/viewvc/php/php-src/branches/PHP_5_3_2/ext/standard/php_rand.h?view=markup */
if (version_compare(PHP_VERSION, '5.2.5', '<=')) {
static $seeded;
if (!isset($seeded)) {
$seeded = true;
mt_srand(fmod(time() * getmypid(), 0x7FFFFFFF) ^ fmod(1000000 * lcg_value(), 0x7FFFFFFF));
}
}
static $crypto;
// The CSPRNG's Yarrow and Fortuna periodically reseed. This function can be reseeded by hitting F5
// in the browser and reloading the page.
if (!isset($crypto)) {
$key = $iv = '';
for ($i = 0; $i < 8; $i++) {
$key.= pack('n', mt_rand(0, 0xFFFF));
$iv .= pack('n', mt_rand(0, 0xFFFF));
}
switch (true) {
case class_exists('Crypt_AES'):
$crypto = new Crypt_AES(CRYPT_AES_MODE_CTR);
break;
case class_exists('Crypt_TripleDES'):
$crypto = new Crypt_TripleDES(CRYPT_DES_MODE_CTR);
break;
case class_exists('Crypt_DES'):
$crypto = new Crypt_DES(CRYPT_DES_MODE_CTR);
break;
case class_exists('Crypt_RC4'):
$crypto = new Crypt_RC4();
break;
default:
extract(unpack('Nrandom', pack('H*', sha1(mt_rand(0, 0x7FFFFFFF)))));
return abs($random) % ($max - $min) + $min;
}
$crypto->setKey($key);
$crypto->setIV($iv);
$crypto->enableContinuousBuffer();
}
extract(unpack('Nrandom', $crypto->encrypt("\0\0\0\0")));
return abs($random) % ($max - $min) + $min;
}
?>
