Subversion Repositories oidplus

<?php

/**

 * Random Number Generator

 *

 * PHP version 5

 *

 * Here's a short example of how to use this library:

 * <code>

 * <?php

 *    include 'vendor/autoload.php';

 *

 *    echo bin2hex(\phpseclib3\Crypt\Random::string(8));

 * ?>

 * </code>

 *

 * @category  Crypt

 * @package   Random

 * @author    Jim Wigginton <terrafrost@php.net>

 * @copyright 2007 Jim Wigginton

 * @license   http://www.opensource.org/licenses/mit-license.html  MIT License

 * @link      http://phpseclib.sourceforge.net

 */

namespace phpseclib3\Crypt;

/**

 * Pure-PHP Random Number Generator

 *

 * @package Random

 * @author  Jim Wigginton <terrafrost@php.net>

 * @access  public

 */

abstract class Random

{

    /**

     * Generate a random string.

     *

     * Although microoptimizations are generally discouraged as they impair readability this function is ripe with

     * microoptimizations because this function has the potential of being called a huge number of times.

     * eg. for RSA key generation.

     *

     * @param int $length

     * @throws \RuntimeException if a symmetric cipher is needed but not loaded

     * @return string

     */

    public static function string($length)

    {

        if (!$length) {

            return '';

        }

        try {

            return random_bytes($length);

        } catch (\Exception $e) {

            // random_compat will throw an Exception, which in PHP 5 does not implement Throwable

        } catch (\Throwable $e) {

            // If a sufficient source of randomness is unavailable, random_bytes() will throw an

            // object that implements the Throwable interface (Exception, TypeError, Error).

            // We don't actually need to do anything here. The string() method should just continue

            // as normal. Note, however, that if we don't have a sufficient source of randomness for

            // random_bytes(), most of the other calls here will fail too, so we'll end up using

            // the PHP implementation.

        }

        // at this point we have no choice but to use a pure-PHP CSPRNG

        // cascade entropy across multiple PHP instances by fixing the session and collecting all

        // environmental variables, including the previous session data and the current session

        // data.

        //

        // mt_rand seeds itself by looking at the PID and the time, both of which are (relatively)

        // easy to guess at. linux uses mouse clicks, keyboard timings, etc, as entropy sources, but

        // PHP isn't low level to be able to use those as sources and on a web server there's not likely

        // going to be a ton of keyboard or mouse action. web servers do have one thing that we can use

        // however, a ton of people visiting the website. obviously you don't want to base your seeding

        // solely on parameters a potential attacker sends but (1) not everything in $_SERVER is controlled

        // by the user and (2) this isn't just looking at the data sent by the current user - it's based

        // on the data sent by all users. one user requests the page and a hash of their info is saved.

        // another user visits the page and the serialization of their data is utilized along with the

        // server environment stuff and a hash of the previous http request data (which itself utilizes

        // a hash of the session data before that). certainly an attacker should be assumed to have

        // full control over his own http requests. he, however, is not going to have control over

        // everyone's http requests.

        static $crypto = false, $v;

        if ($crypto === false) {

            // save old session data

            $old_session_id = session_id();

            $old_use_cookies = ini_get('session.use_cookies');

            $old_session_cache_limiter = session_cache_limiter();

            $_OLD_SESSION = isset($_SESSION) ? $_SESSION : false;

            if ($old_session_id != '') {

                session_write_close();

            }

            session_id(1);

            ini_set('session.use_cookies', 0);

            session_cache_limiter('');

            session_start();

            $v = (isset($_SERVER) ? self::safe_serialize($_SERVER) : '') .

                 (isset($_POST) ? self::safe_serialize($_POST) : '') .

                 (isset($_GET) ? self::safe_serialize($_GET) : '') .

                 (isset($_COOKIE) ? self::safe_serialize($_COOKIE) : '') .

                 self::safe_serialize($GLOBALS) .

                 self::safe_serialize($_SESSION) .

                 self::safe_serialize($_OLD_SESSION);

            $v = $seed = $_SESSION['seed'] = sha1($v, true);

            if (!isset($_SESSION['count'])) {

                $_SESSION['count'] = 0;

            }

            $_SESSION['count']++;

            session_write_close();

            // restore old session data

            if ($old_session_id != '') {

                session_id($old_session_id);

                session_start();

                ini_set('session.use_cookies', $old_use_cookies);

                session_cache_limiter($old_session_cache_limiter);

            } else {

                if ($_OLD_SESSION !== false) {

                    $_SESSION = $_OLD_SESSION;

                    unset($_OLD_SESSION);

                } else {

                    unset($_SESSION);

                }

            }

            // in SSH2 a shared secret and an exchange hash are generated through the key exchange process.

            // 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.

            // if the hash doesn't produce enough a key or an IV that's long enough concat successive hashes of the

            // original hash and the current hash. we'll be emulating that. for more info see the following URL:

            //

            // http://tools.ietf.org/html/rfc4253#section-7.2

            //

            // see the is_string($crypto) part for an example of how to expand the keys

            $key = sha1($seed . 'A', true);

            $iv = sha1($seed . 'C', true);

            // ciphers are used as per the nist.gov link below. also, see this link:

            //

            // http://en.wikipedia.org/wiki/Cryptographically_secure_pseudorandom_number_generator#Designs_based_on_cryptographic_primitives

            switch (true) {

                case class_exists('\phpseclib3\Crypt\AES'):

                    $crypto = new AES('ctr');

                    break;

                case class_exists('\phpseclib3\Crypt\Twofish'):

                    $crypto = new Twofish('ctr');

                    break;

                case class_exists('\phpseclib3\Crypt\Blowfish'):

                    $crypto = new Blowfish('ctr');

                    break;

                case class_exists('\phpseclib3\Crypt\TripleDES'):

                    $crypto = new TripleDES('ctr');

                    break;

                case class_exists('\phpseclib3\Crypt\DES'):

                    $crypto = new DES('ctr');

                    break;

                case class_exists('\phpseclib3\Crypt\RC4'):

                    $crypto = new RC4();

                    break;

                default:

                    throw new \RuntimeException(__CLASS__ . ' requires at least one symmetric cipher be loaded');

            }

            $crypto->setKey(substr($key, 0, $crypto->getKeyLength() >> 3));

            $crypto->setIV(substr($iv, 0, $crypto->getBlockLength() >> 3));

            $crypto->enableContinuousBuffer();

        }

        //return $crypto->encrypt(str_repeat("\0", $length));

        // the following is based off of ANSI X9.31:

        //

        // http://csrc.nist.gov/groups/STM/cavp/documents/rng/931rngext.pdf

        //

        // OpenSSL uses that same standard for it's random numbers:

        //

        // http://www.opensource.apple.com/source/OpenSSL/OpenSSL-38/openssl/fips-1.0/rand/fips_rand.c

        // (do a search for "ANS X9.31 A.2.4")

        $result = '';

        while (strlen($result) < $length) {

            $i = $crypto->encrypt(microtime()); // strlen(microtime()) == 21

            $r = $crypto->encrypt($i ^ $v); // strlen($v) == 20

            $v = $crypto->encrypt($r ^ $i); // strlen($r) == 20

            $result .= $r;

        }

        return substr($result, 0, $length);

    }

    /**

     * Safely serialize variables

     *

     * If a class has a private __sleep() it'll emit a warning

     * @return mixed

     * @param mixed $arr

     */

    private static function safe_serialize(&$arr)

    {

        if (is_object($arr)) {

            return '';

        }

        if (!is_array($arr)) {

            return serialize($arr);

        }

        // prevent circular array recursion

        if (isset($arr['__phpseclib_marker'])) {

            return '';

        }

        $safearr = [];

        $arr['__phpseclib_marker'] = true;

        foreach (array_keys($arr) as $key) {

            // do not recurse on the '__phpseclib_marker' key itself, for smaller memory usage

            if ($key !== '__phpseclib_marker') {

                $safearr[$key] = self::safe_serialize($arr[$key]);

            }

        }

        unset($arr['__phpseclib_marker']);

        return serialize($safearr);

    }

}