1<?php 2 3/** 4 * Random Number Generator 5 * 6 * PHP version 5 7 * 8 * Here's a short example of how to use this library: 9 * <code> 10 * <?php 11 * include 'vendor/autoload.php'; 12 * 13 * echo bin2hex(\phpseclib3\Crypt\Random::string(8)); 14 * ?> 15 * </code> 16 * 17 * @category Crypt 18 * @package Random 19 * @author Jim Wigginton <terrafrost@php.net> 20 * @copyright 2007 Jim Wigginton 21 * @license http://www.opensource.org/licenses/mit-license.html MIT License 22 * @link http://phpseclib.sourceforge.net 23 */ 24 25namespace phpseclib3\Crypt; 26 27/** 28 * Pure-PHP Random Number Generator 29 * 30 * @package Random 31 * @author Jim Wigginton <terrafrost@php.net> 32 * @access public 33 */ 34abstract class Random 35{ 36 /** 37 * Generate a random string. 38 * 39 * Although microoptimizations are generally discouraged as they impair readability this function is ripe with 40 * microoptimizations because this function has the potential of being called a huge number of times. 41 * eg. for RSA key generation. 42 * 43 * @param int $length 44 * @throws \RuntimeException if a symmetric cipher is needed but not loaded 45 * @return string 46 */ 47 public static function string($length) 48 { 49 if (!$length) { 50 return ''; 51 } 52 53 try { 54 return random_bytes($length); 55 } catch (\Exception $e) { 56 // random_compat will throw an Exception, which in PHP 5 does not implement Throwable 57 } catch (\Throwable $e) { 58 // If a sufficient source of randomness is unavailable, random_bytes() will throw an 59 // object that implements the Throwable interface (Exception, TypeError, Error). 60 // We don't actually need to do anything here. The string() method should just continue 61 // as normal. Note, however, that if we don't have a sufficient source of randomness for 62 // random_bytes(), most of the other calls here will fail too, so we'll end up using 63 // the PHP implementation. 64 } 65 // at this point we have no choice but to use a pure-PHP CSPRNG 66 67 // cascade entropy across multiple PHP instances by fixing the session and collecting all 68 // environmental variables, including the previous session data and the current session 69 // data. 70 // 71 // mt_rand seeds itself by looking at the PID and the time, both of which are (relatively) 72 // easy to guess at. linux uses mouse clicks, keyboard timings, etc, as entropy sources, but 73 // PHP isn't low level to be able to use those as sources and on a web server there's not likely 74 // going to be a ton of keyboard or mouse action. web servers do have one thing that we can use 75 // however, a ton of people visiting the website. obviously you don't want to base your seeding 76 // solely on parameters a potential attacker sends but (1) not everything in $_SERVER is controlled 77 // by the user and (2) this isn't just looking at the data sent by the current user - it's based 78 // on the data sent by all users. one user requests the page and a hash of their info is saved. 79 // another user visits the page and the serialization of their data is utilized along with the 80 // server environment stuff and a hash of the previous http request data (which itself utilizes 81 // a hash of the session data before that). certainly an attacker should be assumed to have 82 // full control over his own http requests. he, however, is not going to have control over 83 // everyone's http requests. 84 static $crypto = false, $v; 85 if ($crypto === false) { 86 // save old session data 87 $old_session_id = session_id(); 88 $old_use_cookies = ini_get('session.use_cookies'); 89 $old_session_cache_limiter = session_cache_limiter(); 90 $_OLD_SESSION = isset($_SESSION) ? $_SESSION : false; 91 if ($old_session_id != '') { 92 session_write_close(); 93 } 94 95 session_id(1); 96 ini_set('session.use_cookies', 0); 97 session_cache_limiter(''); 98 session_start(); 99 100 $v = (isset($_SERVER) ? self::safe_serialize($_SERVER) : '') . 101 (isset($_POST) ? self::safe_serialize($_POST) : '') . 102 (isset($_GET) ? self::safe_serialize($_GET) : '') . 103 (isset($_COOKIE) ? self::safe_serialize($_COOKIE) : '') . 104 self::safe_serialize($GLOBALS) . 105 self::safe_serialize($_SESSION) . 106 self::safe_serialize($_OLD_SESSION); 107 $v = $seed = $_SESSION['seed'] = sha1($v, true); 108 if (!isset($_SESSION['count'])) { 109 $_SESSION['count'] = 0; 110 } 111 $_SESSION['count']++; 112 113 session_write_close(); 114 115 // restore old session data 116 if ($old_session_id != '') { 117 session_id($old_session_id); 118 session_start(); 119 ini_set('session.use_cookies', $old_use_cookies); 120 session_cache_limiter($old_session_cache_limiter); 121 } else { 122 if ($_OLD_SESSION !== false) { 123 $_SESSION = $_OLD_SESSION; 124 unset($_OLD_SESSION); 125 } else { 126 unset($_SESSION); 127 } 128 } 129 130 // in SSH2 a shared secret and an exchange hash are generated through the key exchange process. 131 // the IV client to server is the hash of that "nonce" with the letter A and for the encryption key it's the letter C. 132 // if the hash doesn't produce enough a key or an IV that's long enough concat successive hashes of the 133 // original hash and the current hash. we'll be emulating that. for more info see the following URL: 134 // 135 // http://tools.ietf.org/html/rfc4253#section-7.2 136 // 137 // see the is_string($crypto) part for an example of how to expand the keys 138 $key = sha1($seed . 'A', true); 139 $iv = sha1($seed . 'C', true); 140 141 // ciphers are used as per the nist.gov link below. also, see this link: 142 // 143 // http://en.wikipedia.org/wiki/Cryptographically_secure_pseudorandom_number_generator#Designs_based_on_cryptographic_primitives 144 switch (true) { 145 case class_exists('\phpseclib3\Crypt\AES'): 146 $crypto = new AES('ctr'); 147 break; 148 case class_exists('\phpseclib3\Crypt\Twofish'): 149 $crypto = new Twofish('ctr'); 150 break; 151 case class_exists('\phpseclib3\Crypt\Blowfish'): 152 $crypto = new Blowfish('ctr'); 153 break; 154 case class_exists('\phpseclib3\Crypt\TripleDES'): 155 $crypto = new TripleDES('ctr'); 156 break; 157 case class_exists('\phpseclib3\Crypt\DES'): 158 $crypto = new DES('ctr'); 159 break; 160 case class_exists('\phpseclib3\Crypt\RC4'): 161 $crypto = new RC4(); 162 break; 163 default: 164 throw new \RuntimeException(__CLASS__ . ' requires at least one symmetric cipher be loaded'); 165 } 166 167 $crypto->setKey(substr($key, 0, $crypto->getKeyLength() >> 3)); 168 $crypto->setIV(substr($iv, 0, $crypto->getBlockLength() >> 3)); 169 $crypto->enableContinuousBuffer(); 170 } 171 172 //return $crypto->encrypt(str_repeat("\0", $length)); 173 174 // the following is based off of ANSI X9.31: 175 // 176 // http://csrc.nist.gov/groups/STM/cavp/documents/rng/931rngext.pdf 177 // 178 // OpenSSL uses that same standard for it's random numbers: 179 // 180 // http://www.opensource.apple.com/source/OpenSSL/OpenSSL-38/openssl/fips-1.0/rand/fips_rand.c 181 // (do a search for "ANS X9.31 A.2.4") 182 $result = ''; 183 while (strlen($result) < $length) { 184 $i = $crypto->encrypt(microtime()); // strlen(microtime()) == 21 185 $r = $crypto->encrypt($i ^ $v); // strlen($v) == 20 186 $v = $crypto->encrypt($r ^ $i); // strlen($r) == 20 187 $result .= $r; 188 } 189 190 return substr($result, 0, $length); 191 } 192 193 /** 194 * Safely serialize variables 195 * 196 * If a class has a private __sleep() it'll emit a warning 197 * @return mixed 198 * @param mixed $arr 199 */ 200 private static function safe_serialize(&$arr) 201 { 202 if (is_object($arr)) { 203 return ''; 204 } 205 if (!is_array($arr)) { 206 return serialize($arr); 207 } 208 // prevent circular array recursion 209 if (isset($arr['__phpseclib_marker'])) { 210 return ''; 211 } 212 $safearr = []; 213 $arr['__phpseclib_marker'] = true; 214 foreach (array_keys($arr) as $key) { 215 // do not recurse on the '__phpseclib_marker' key itself, for smaller memory usage 216 if ($key !== '__phpseclib_marker') { 217 $safearr[$key] = self::safe_serialize($arr[$key]); 218 } 219 } 220 unset($arr['__phpseclib_marker']); 221 return serialize($safearr); 222 } 223} 224