247 lines
11 KiB
PHP
247 lines
11 KiB
PHP
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<?php
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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 bin2hex(crypt_random_string(8));
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* ?>
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* </code>
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*
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* LICENSE: Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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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.opensource.org/licenses/mit-license.html MIT License
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* @link http://phpseclib.sourceforge.net
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*/
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/**
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* "Is Windows" test
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*
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* @access private
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*/
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define('CRYPT_RANDOM_IS_WINDOWS', strtoupper(substr(PHP_OS, 0, 3)) === 'WIN');
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/**
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* Generate a random string.
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*
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* Although microoptimizations are generally discouraged as they impair readability this function is ripe with
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* microoptimizations because this function has the potential of being called a huge number of times.
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* eg. for RSA key generation.
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*
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* @param Integer $length
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* @return String
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* @access public
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*/
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function crypt_random_string($length)
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{
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if (CRYPT_RANDOM_IS_WINDOWS) {
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// method 1. prior to PHP 5.3 this would call rand() on windows hence the function_exists('class_alias') call.
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// ie. class_alias is a function that was introduced in PHP 5.3
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if (function_exists('mcrypt_create_iv') && function_exists('class_alias')) {
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return mcrypt_create_iv($length);
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}
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// method 2. openssl_random_pseudo_bytes was introduced in PHP 5.3.0 but prior to PHP 5.3.4 there was,
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// to quote <http://php.net/ChangeLog-5.php#5.3.4>, "possible blocking behavior". as of 5.3.4
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// openssl_random_pseudo_bytes and mcrypt_create_iv do the exact same thing on Windows. ie. they both
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// call php_win32_get_random_bytes():
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//
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// https://github.com/php/php-src/blob/7014a0eb6d1611151a286c0ff4f2238f92c120d6/ext/openssl/openssl.c#L5008
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// https://github.com/php/php-src/blob/7014a0eb6d1611151a286c0ff4f2238f92c120d6/ext/mcrypt/mcrypt.c#L1392
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//
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// php_win32_get_random_bytes() is defined thusly:
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//
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// https://github.com/php/php-src/blob/7014a0eb6d1611151a286c0ff4f2238f92c120d6/win32/winutil.c#L80
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//
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// we're calling it, all the same, in the off chance that the mcrypt extension is not available
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if (function_exists('openssl_random_pseudo_bytes') && version_compare(PHP_VERSION, '5.3.4', '>=')) {
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return openssl_random_pseudo_bytes($length);
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}
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} else {
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// method 1. the fastest
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if (function_exists('openssl_random_pseudo_bytes')) {
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return openssl_random_pseudo_bytes($length);
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}
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// method 2
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static $fp = true;
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if ($fp === true) {
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// warning's will be output unles the error suppression operator is used. errors such as
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// "open_basedir restriction in effect", "Permission denied", "No such file or directory", etc.
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$fp = @fopen('/dev/urandom', 'rb');
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}
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if ($fp !== true && $fp !== false) { // surprisingly faster than !is_bool() or is_resource()
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return fread($fp, $length);
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}
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// method 3. pretty much does the same thing as method 2 per the following url:
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// https://github.com/php/php-src/blob/7014a0eb6d1611151a286c0ff4f2238f92c120d6/ext/mcrypt/mcrypt.c#L1391
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// surprisingly slower than method 2. maybe that's because mcrypt_create_iv does a bunch of error checking that we're
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// not doing. regardless, this'll only be called if this PHP script couldn't open /dev/urandom due to open_basedir
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// restrictions or some such
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if (function_exists('mcrypt_create_iv')) {
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return mcrypt_create_iv($length, MCRYPT_DEV_URANDOM);
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}
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}
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// at this point we have no choice but to use a pure-PHP CSPRNG
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// cascade entropy across multiple PHP instances by fixing the session and collecting all
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// environmental variables, including the previous session data and the current session
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// data.
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//
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// mt_rand seeds itself by looking at the PID and the time, both of which are (relatively)
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// easy to guess at. linux uses mouse clicks, keyboard timings, etc, as entropy sources, but
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// PHP isn't low level to be able to use those as sources and on a web server there's not likely
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// going to be a ton of keyboard or mouse action. web servers do have one thing that we can use
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// however. a ton of people visiting the website. obviously you don't want to base your seeding
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// soley on parameters a potential attacker sends but (1) not everything in $_SERVER is controlled
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// by the user and (2) this isn't just looking at the data sent by the current user - it's based
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// on the data sent by all users. one user requests the page and a hash of their info is saved.
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// another user visits the page and the serialization of their data is utilized along with the
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// server envirnment stuff and a hash of the previous http request data (which itself utilizes
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// a hash of the session data before that). certainly an attacker should be assumed to have
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// full control over his own http requests. he, however, is not going to have control over
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// everyone's http requests.
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static $crypto = false, $v;
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if ($crypto === false) {
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// save old session data
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$old_session_id = session_id();
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$old_use_cookies = ini_get('session.use_cookies');
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$old_session_cache_limiter = session_cache_limiter();
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$_OLD_SESSION = isset($_SESSION) ? $_SESSION : false;
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if ($old_session_id != '') {
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session_write_close();
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}
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session_id(1);
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ini_set('session.use_cookies', 0);
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session_cache_limiter('');
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session_start();
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$v = $seed = $_SESSION['seed'] = pack('H*', sha1(
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serialize($_SERVER) .
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serialize($_POST) .
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serialize($_GET) .
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serialize($_COOKIE) .
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serialize($GLOBALS) .
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serialize($_SESSION) .
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serialize($_OLD_SESSION)
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));
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if (!isset($_SESSION['count'])) {
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$_SESSION['count'] = 0;
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}
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$_SESSION['count']++;
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session_write_close();
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// restore old session data
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if ($old_session_id != '') {
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session_id($old_session_id);
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session_start();
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ini_set('session.use_cookies', $old_use_cookies);
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session_cache_limiter($old_session_cache_limiter);
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} else {
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if ($_OLD_SESSION !== false) {
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$_SESSION = $_OLD_SESSION;
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unset($_OLD_SESSION);
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} else {
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unset($_SESSION);
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}
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}
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// in SSH2 a shared secret and an exchange hash are generated through the key exchange process.
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// the IV client to server is the hash of that "nonce" with the letter A and for the encryption key it's the letter C.
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// if the hash doesn't produce enough a key or an IV that's long enough concat successive hashes of the
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// original hash and the current hash. we'll be emulating that. for more info see the following URL:
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//
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// http://tools.ietf.org/html/rfc4253#section-7.2
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//
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// see the is_string($crypto) part for an example of how to expand the keys
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$key = pack('H*', sha1($seed . 'A'));
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$iv = pack('H*', sha1($seed . 'C'));
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// ciphers are used as per the nist.gov link below. also, see this link:
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//
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// http://en.wikipedia.org/wiki/Cryptographically_secure_pseudorandom_number_generator#Designs_based_on_cryptographic_primitives
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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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$crypto = $seed;
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return crypt_random_string($length);
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}
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$crypto->setKey($key);
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$crypto->setIV($iv);
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$crypto->enableContinuousBuffer();
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}
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if (is_string($crypto)) {
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// the following is based off of ANSI X9.31:
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//
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// http://csrc.nist.gov/groups/STM/cavp/documents/rng/931rngext.pdf
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//
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// OpenSSL uses that same standard for it's random numbers:
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//
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// http://www.opensource.apple.com/source/OpenSSL/OpenSSL-38/openssl/fips-1.0/rand/fips_rand.c
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// (do a search for "ANS X9.31 A.2.4")
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//
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// ANSI X9.31 recommends ciphers be used and phpseclib does use them if they're available (see
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// later on in the code) but if they're not we'll use sha1
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$result = '';
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while (strlen($result) < $length) { // each loop adds 20 bytes
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// microtime() isn't packed as "densely" as it could be but then neither is that the idea.
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// the idea is simply to ensure that each "block" has a unique element to it.
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$i = pack('H*', sha1(microtime()));
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$r = pack('H*', sha1($i ^ $v));
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$v = pack('H*', sha1($r ^ $i));
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$result.= $r;
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}
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return substr($result, 0, $length);
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}
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//return $crypto->encrypt(str_repeat("\0", $length));
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$result = '';
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while (strlen($result) < $length) {
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$i = $crypto->encrypt(microtime());
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$r = $crypto->encrypt($i ^ $v);
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$v = $crypto->encrypt($r ^ $i);
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$result.= $r;
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}
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return substr($result, 0, $length);
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}
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