220 lines
9.0 KiB
PHP
220 lines
9.0 KiB
PHP
<?php
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/**
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* Random Number Generator
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*
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* PHP version 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 'vendor/autoload.php';
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*
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* echo bin2hex(\phpseclib\Crypt\Random::string(8));
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* ?>
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* </code>
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*
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* @category Crypt
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* @package Random
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* @author Jim Wigginton <terrafrost@php.net>
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* @copyright 2007 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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namespace phpseclib\Crypt;
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/**
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* Pure-PHP Random Number Generator
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*
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* @package Random
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* @author Jim Wigginton <terrafrost@php.net>
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* @access public
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*/
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class Random
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{
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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 int $length
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* @throws \RuntimeException if a symmetric cipher is needed but not loaded
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* @return string
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*/
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static function string($length)
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{
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try {
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return \random_bytes($length);
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} catch (\Exception $e) {
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// random_compat will throw an Exception, which in PHP 5 does not implement Throwable
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} catch (\Throwable $e) {
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// If a sufficient source of randomness is unavailable, random_bytes() will throw an
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// object that implements the Throwable interface (Exception, TypeError, Error).
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// We don't actually need to do anything here. The string() method should just continue
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// as normal. Note, however, that if we don't have a sufficient source of randomness for
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// random_bytes(), most of the other calls here will fail too, so we'll end up using
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// the PHP implementation.
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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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$v = (isset($_SERVER) ? self::safe_serialize($_SERVER) : '') .
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(isset($_POST) ? self::safe_serialize($_POST) : '') .
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(isset($_GET) ? self::safe_serialize($_GET) : '') .
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(isset($_COOKIE) ? self::safe_serialize($_COOKIE) : '') .
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self::safe_serialize($GLOBALS) .
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self::safe_serialize($_SESSION) .
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self::safe_serialize($_OLD_SESSION);
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$v = $seed = $_SESSION['seed'] = sha1($v, true);
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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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$key = sha1($seed . 'A', true);
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$iv = sha1($seed . 'C', true);
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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('\phpseclib\Crypt\AES'):
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$crypto = new AES(Base::MODE_CTR);
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break;
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case class_exists('\phpseclib\Crypt\Twofish'):
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$crypto = new Twofish(Base::MODE_CTR);
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break;
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case class_exists('\phpseclib\Crypt\Blowfish'):
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$crypto = new Blowfish(Base::MODE_CTR);
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break;
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case class_exists('\phpseclib\Crypt\TripleDES'):
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$crypto = new TripleDES(Base::MODE_CTR);
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break;
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case class_exists('\phpseclib\Crypt\DES'):
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$crypto = new DES(Base::MODE_CTR);
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break;
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case class_exists('\phpseclib\Crypt\RC4'):
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$crypto = new RC4();
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break;
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default:
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throw new \RuntimeException(__CLASS__ . ' requires at least one symmetric cipher be loaded');
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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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//return $crypto->encrypt(str_repeat("\0", $length));
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// the following is based off of ANSI X9.31:
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//
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// http://csrc.nist.gov/groups/STM/cavp/documents/rng/931rngext.pdf
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//
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// OpenSSL uses that same standard for it's random numbers:
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//
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// http://www.opensource.apple.com/source/OpenSSL/OpenSSL-38/openssl/fips-1.0/rand/fips_rand.c
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// (do a search for "ANS X9.31 A.2.4")
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$result = '';
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while (strlen($result) < $length) {
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$i = $crypto->encrypt(microtime()); // strlen(microtime()) == 21
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$r = $crypto->encrypt($i ^ $v); // strlen($v) == 20
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$v = $crypto->encrypt($r ^ $i); // strlen($r) == 20
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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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/**
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* Safely serialize variables
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*
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* If a class has a private __sleep() it'll emit a warning
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*
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* @param mixed $arr
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* @access public
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*/
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function safe_serialize(&$arr)
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{
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if (is_object($arr)) {
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return '';
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}
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if (!is_array($arr)) {
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return serialize($arr);
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}
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// prevent circular array recursion
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if (isset($arr['__phpseclib_marker'])) {
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return '';
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}
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$safearr = array();
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$arr['__phpseclib_marker'] = true;
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foreach (array_keys($arr) as $key) {
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// do not recurse on the '__phpseclib_marker' key itself, for smaller memory usage
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if ($key !== '__phpseclib_marker') {
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$safearr[$key] = self::safe_serialize($arr[$key]);
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}
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}
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unset($arr['__phpseclib_marker']);
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return serialize($safearr);
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}
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}
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