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