ILIAS  release_5-4 Revision v5.4.26-12-gabc799a52e6
Random.php
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1 <?php
2 
25 namespace phpseclib\Crypt;
26 
34 
42 class Random
43 {
54  static function string($length)
55  {
56  if (version_compare(PHP_VERSION, '7.0.0', '>=')) {
57  try {
58  return \random_bytes($length);
59  } catch (\Throwable $e) {
60  // If a sufficient source of randomness is unavailable, random_bytes() will throw an
61  // object that implements the Throwable interface (Exception, TypeError, Error).
62  // We don't actually need to do anything here. The string() method should just continue
63  // as normal. Note, however, that if we don't have a sufficient source of randomness for
64  // random_bytes(), most of the other calls here will fail too, so we'll end up using
65  // the PHP implementation.
66  }
67  }
68 
69  if (strtoupper(substr(PHP_OS, 0, 3)) === 'WIN') {
70  // method 1. prior to PHP 5.3 this would call rand() on windows hence the function_exists('class_alias') call.
71  // ie. class_alias is a function that was introduced in PHP 5.3
72  if (extension_loaded('mcrypt') && function_exists('class_alias')) {
73  return mcrypt_create_iv($length);
74  }
75  // method 2. openssl_random_pseudo_bytes was introduced in PHP 5.3.0 but prior to PHP 5.3.4 there was,
76  // to quote <http://php.net/ChangeLog-5.php#5.3.4>, "possible blocking behavior". as of 5.3.4
77  // openssl_random_pseudo_bytes and mcrypt_create_iv do the exact same thing on Windows. ie. they both
78  // call php_win32_get_random_bytes():
79  //
80  // https://github.com/php/php-src/blob/7014a0eb6d1611151a286c0ff4f2238f92c120d6/ext/openssl/openssl.c#L5008
81  // https://github.com/php/php-src/blob/7014a0eb6d1611151a286c0ff4f2238f92c120d6/ext/mcrypt/mcrypt.c#L1392
82  //
83  // php_win32_get_random_bytes() is defined thusly:
84  //
85  // https://github.com/php/php-src/blob/7014a0eb6d1611151a286c0ff4f2238f92c120d6/win32/winutil.c#L80
86  //
87  // we're calling it, all the same, in the off chance that the mcrypt extension is not available
88  if (extension_loaded('openssl') && version_compare(PHP_VERSION, '5.3.4', '>=')) {
89  return openssl_random_pseudo_bytes($length);
90  }
91  } else {
92  // method 1. the fastest
93  if (extension_loaded('openssl')) {
94  return openssl_random_pseudo_bytes($length);
95  }
96  // method 2
97  static $fp = true;
98  if ($fp === true) {
99  // warning's will be output unles the error suppression operator is used. errors such as
100  // "open_basedir restriction in effect", "Permission denied", "No such file or directory", etc.
101  $fp = @fopen('/dev/urandom', 'rb');
102  }
103  if ($fp !== true && $fp !== false) { // surprisingly faster than !is_bool() or is_resource()
104  return fread($fp, $length);
105  }
106  // method 3. pretty much does the same thing as method 2 per the following url:
107  // https://github.com/php/php-src/blob/7014a0eb6d1611151a286c0ff4f2238f92c120d6/ext/mcrypt/mcrypt.c#L1391
108  // surprisingly slower than method 2. maybe that's because mcrypt_create_iv does a bunch of error checking that we're
109  // not doing. regardless, this'll only be called if this PHP script couldn't open /dev/urandom due to open_basedir
110  // restrictions or some such
111  if (extension_loaded('mcrypt')) {
112  return mcrypt_create_iv($length, MCRYPT_DEV_URANDOM);
113  }
114  }
115  // at this point we have no choice but to use a pure-PHP CSPRNG
116 
117  // cascade entropy across multiple PHP instances by fixing the session and collecting all
118  // environmental variables, including the previous session data and the current session
119  // data.
120  //
121  // mt_rand seeds itself by looking at the PID and the time, both of which are (relatively)
122  // easy to guess at. linux uses mouse clicks, keyboard timings, etc, as entropy sources, but
123  // PHP isn't low level to be able to use those as sources and on a web server there's not likely
124  // going to be a ton of keyboard or mouse action. web servers do have one thing that we can use
125  // however, a ton of people visiting the website. obviously you don't want to base your seeding
126  // soley on parameters a potential attacker sends but (1) not everything in $_SERVER is controlled
127  // by the user and (2) this isn't just looking at the data sent by the current user - it's based
128  // on the data sent by all users. one user requests the page and a hash of their info is saved.
129  // another user visits the page and the serialization of their data is utilized along with the
130  // server envirnment stuff and a hash of the previous http request data (which itself utilizes
131  // a hash of the session data before that). certainly an attacker should be assumed to have
132  // full control over his own http requests. he, however, is not going to have control over
133  // everyone's http requests.
134  static $crypto = false, $v;
135  if ($crypto === false) {
136  // save old session data
137  $old_session_id = session_id();
138  $old_use_cookies = ini_get('session.use_cookies');
139  $old_session_cache_limiter = session_cache_limiter();
140  $_OLD_SESSION = isset($_SESSION) ? $_SESSION : false;
141  if ($old_session_id != '') {
142  session_write_close();
143  }
144 
145  session_id(1);
146  ini_set('session.use_cookies', 0);
147  session_cache_limiter('');
148  session_start();
149 
150  $v = $seed = $_SESSION['seed'] = pack('H*', sha1(
151  serialize($_SERVER) .
152  serialize($_POST) .
153  serialize($_GET) .
154  serialize($_COOKIE) .
155  serialize($GLOBALS) .
156  serialize($_SESSION) .
157  serialize($_OLD_SESSION)
158  ));
159  if (!isset($_SESSION['count'])) {
160  $_SESSION['count'] = 0;
161  }
162  $_SESSION['count']++;
163 
164  session_write_close();
165 
166  // restore old session data
167  if ($old_session_id != '') {
168  session_id($old_session_id);
169  session_start();
170  ini_set('session.use_cookies', $old_use_cookies);
171  session_cache_limiter($old_session_cache_limiter);
172  } else {
173  if ($_OLD_SESSION !== false) {
174  $_SESSION = $_OLD_SESSION;
175  unset($_OLD_SESSION);
176  } else {
177  unset($_SESSION);
178  }
179  }
180 
181  // in SSH2 a shared secret and an exchange hash are generated through the key exchange process.
182  // the IV client to server is the hash of that "nonce" with the letter A and for the encryption key it's the letter C.
183  // if the hash doesn't produce enough a key or an IV that's long enough concat successive hashes of the
184  // original hash and the current hash. we'll be emulating that. for more info see the following URL:
185  //
186  // http://tools.ietf.org/html/rfc4253#section-7.2
187  //
188  // see the is_string($crypto) part for an example of how to expand the keys
189  $key = pack('H*', sha1($seed . 'A'));
190  $iv = pack('H*', sha1($seed . 'C'));
191 
192  // ciphers are used as per the nist.gov link below. also, see this link:
193  //
194  // http://en.wikipedia.org/wiki/Cryptographically_secure_pseudorandom_number_generator#Designs_based_on_cryptographic_primitives
195  switch (true) {
196  case class_exists('\phpseclib\Crypt\AES'):
197  $crypto = new AES(Base::MODE_CTR);
198  break;
199  case class_exists('\phpseclib\Crypt\Twofish'):
200  $crypto = new Twofish(Base::MODE_CTR);
201  break;
202  case class_exists('\phpseclib\Crypt\Blowfish'):
203  $crypto = new Blowfish(Base::MODE_CTR);
204  break;
205  case class_exists('\phpseclib\Crypt\TripleDES'):
206  $crypto = new TripleDES(Base::MODE_CTR);
207  break;
208  case class_exists('\phpseclib\Crypt\DES'):
209  $crypto = new DES(Base::MODE_CTR);
210  break;
211  case class_exists('\phpseclib\Crypt\RC4'):
212  $crypto = new RC4();
213  break;
214  default:
215  user_error(__CLASS__ . ' requires at least one symmetric cipher be loaded');
216  return false;
217  }
218 
219  $crypto->setKey($key);
220  $crypto->setIV($iv);
221  $crypto->enableContinuousBuffer();
222  }
223 
224  //return $crypto->encrypt(str_repeat("\0", $length));
225 
226  // the following is based off of ANSI X9.31:
227  //
228  // http://csrc.nist.gov/groups/STM/cavp/documents/rng/931rngext.pdf
229  //
230  // OpenSSL uses that same standard for it's random numbers:
231  //
232  // http://www.opensource.apple.com/source/OpenSSL/OpenSSL-38/openssl/fips-1.0/rand/fips_rand.c
233  // (do a search for "ANS X9.31 A.2.4")
234  $result = '';
235  while (strlen($result) < $length) {
236  $i = $crypto->encrypt(microtime()); // strlen(microtime()) == 21
237  $r = $crypto->encrypt($i ^ $v); // strlen($v) == 20
238  $v = $crypto->encrypt($r ^ $i); // strlen($r) == 20
239  $result.= $r;
240  }
241  return substr($result, 0, $length);
242  }
243 }
$_COOKIE['client_id']
Definition: server.php:9
if((!isset($_SERVER['DOCUMENT_ROOT'])) OR(empty($_SERVER['DOCUMENT_ROOT']))) $_SERVER['DOCUMENT_ROOT']
$_SESSION["AccountId"]
$result
Pure-PHP implementation of Twofish.
Pure-PHP implementation of Blowfish.
$_GET["client_id"]
const MODE_CTR
#+ public
Definition: Base.php:62
Pure-PHP implementations of keyed-hash message authentication codes (HMACs) and various cryptographic...
Definition: AES.php:50
$r
Definition: example_031.php:79
Pure-PHP Random Number Generator.
Pure-PHP implementation of Triple DES.
Pure-PHP implementation of RC4.
$i
Definition: disco.tpl.php:19
static string($length)
Generate a random string.
Definition: Random.php:54
Pure-PHP implementation of DES.
Pure-PHP implementation of AES.
$key
Definition: croninfo.php:18
$_POST["username"]
$GLOBALS['JPEG_Segment_Names']
Global Variable: XMP_tag_captions.